KR101803675B1 - Polarizing plate and image display device - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate improved in crack resistance under an environment in contact with water.
The above object is achieved by a polarizing plate comprising a polarizer and a functional layer laminated on at least one side of the polarizer, wherein the polarizing plate has a value obtained by subtracting the modulus of elasticity of the polarizing film in the transmission axis direction of the functional layer from the modulus of elasticity of the polarizer in the transmission axis direction Is solved.

Description

[0001] POLARIZING PLATE AND IMAGE DISPLAY DEVICE [0002]

The present invention relates to a polarizing plate usable in various optical applications. The present invention also relates to an image display apparatus having such a polarizing plate.

The polarizing plate is widely used as a polarizing light supplying element in an image display apparatus and also as a polarizing light detecting element. For such a polarizing plate, for example, a polarizer obtained by stretching, dyeing, crosslinking or the like of a polyvinyl alcohol resin film is suitably employed. If a crack is generated in the polarizer, an appearance defect may occur and an optical problem called " light dropout " may occur. Conventionally, various proposals have been made in order to prevent the occurrence of cracks in the polarizer (see Patent Documents 1 to 5).

Patent Document 1: JP-A-2013-72951 Patent Document 2: Japanese Patent Laid-Open Publication No. 145445/1995 Patent Document 3: Japanese Patent Laid-Open Publication No. 2011-221278 Patent Document 4: Japanese Patent Application Laid-Open No. 2004-29367 Patent Document 5: Japanese Patent Application Laid-Open No. 2004-20830

Cracking in the polarizer can be caused by various factors. Typically, cracks may occur due to a sudden temperature change (thermal shock) in the ambient atmosphere exposed during use of the product. In this case, a heat shock acceleration test, for example, a heat cycle between -40 DEG C and 85 DEG C is repeated 20 times The degree of cracking can be evaluated by a test (Patent Document 2) or a test in which a heat cycle between -35 占 폚 and 85 占 폚 is repeated 500 times (Patent Document 4). In addition, when a polarizing laminated film comprising a base film and a polarizing layer laminated and stretched thereon is transferred to a protective film (Patent Document 3) or a polarizing plate including a polarizer is cut Cracks may be generated by a force (physical / mechanical impact) applied to the substrate (Patent Document 4). In this case, the degree of cracking can be confirmed after these operations.

On the other hand, the inventors of the present invention have focused on the fact that cracks can be generated by condensation that may occur during use of the product. Since condensation causes contact with water, it is considered that a crack occurs due to a mechanism different from that caused by a simple thermal shock or physical / mechanical shock as described above.

An object of the present invention is to provide a polarizing plate improved in crack resistance under an environment in contact with water.

As a result of research conducted by the present inventors, a crack acceleration test (including immersion in water) in which a polarizer and a polarizing plate including a functional layer stacked on at least one surface thereof were bonded to a glass plate was subjected to a crack acceleration test It has been found that cracks can be generated by extending in the direction of the absorption axis from the end face of the side along the transmission axis direction. The present inventors have found that the smaller the modulus of elasticity in the direction of the polarizer transmission axis of the functional layer stacked on at least one side of the polarizer is, the less likely it is to crack under an environment in contact with water and the smaller the modulus of elasticity of the polarizer in the transmission axis direction, Has a unique property that cracks are unlikely to occur under an environment in contact with water as the difference in modulus of elasticity in the direction of the transmission axis of the polarizer is greater. As a result of further studies, the present invention has been completed.

The present invention includes the following [1] to [7].

[1] A polarizing plate comprising a polarizer and a functional layer laminated on at least one surface of the polarizer, wherein a value obtained by subtracting the modulus of elasticity of the polarizing layer in the transmission axis direction of the functional layer from the modulus of elasticity of the polarizer in the transmission axis direction is -1100 MPa or more.

[2] The polarizer according to [1], wherein the functional layer comprises a protective film.

[3] The polarizer according to [1] or [2], wherein the functional layer comprises a retardation film.

[4] A polarizer according to any one of [1] to [3], wherein a functional layer is laminated on one side of a polarizer and a pressure-sensitive adhesive layer is laminated on the other side of the polarizer.

[5] The polarizer according to any one of [1] to [4], wherein a pressure-sensitive adhesive layer or a pressure-sensitive adhesive layer having a release layer is laminated on the outermost surface of the polarizing plate on one side.

[6] The polarizer according to [4] or [5], wherein the pressure-sensitive adhesive layer has a modulus of elasticity in the direction of the polarizer transmission axis of 1000 kPa or less.

[7] An image display device comprising a liquid crystal cell or an organic electroluminescence element and the polarizing plate described in any one of [1] to [6].

According to the present invention, there is provided a polarizing plate improved in crack resistance under an environment in contact with water. Further, according to the present invention, an image display apparatus having such a polarizing plate is provided. Such a polarizing plate and an image display apparatus of the present invention can exhibit high crack resistance against condensation.

1 shows a schematic sectional view of a polarizing plate in one embodiment of the present invention.
2 is a schematic cross-sectional view of a polarizing plate in another embodiment of the present invention.
Fig. 3 shows a schematic sectional view of a polarizing plate in another embodiment of the present invention.
4 is a schematic sectional view of an image display apparatus according to one embodiment of the present invention.

Hereinafter, the polarizing plate and the image display apparatus according to the present invention will be described in detail, but the present invention is not limited to these embodiments.

The polarizing plate of the present invention comprises a polarizer and a functional layer laminated on at least one side of the polarizer. 1, the polarizing plate 10 includes a polarizer 1, first and second functional layers 3 and 3 stacked on both surfaces of the polarizer 1, (5) may be included. The polarizing plate of the present invention is also characterized in that a polarizer 1 of at least one functional layer (second functional layer 5 in the illustrated embodiment) as in the polarizing plate 11 shown in Fig. The pressure-sensitive adhesive layer 7 may be laminated on the opposite surface. The pressure-sensitive adhesive layer 7 may or may not have a release layer (not shown) on the outermost surface. 3, the polarizing plate 12 includes a polarizer 1, a functional layer 3 laminated on one surface of the polarizer 1, and a functional layer 3 laminated on the other side of the polarizer 1. In this embodiment, Sensitive adhesive layer (7). However, the configuration (stacking order, etc.) of the polarizing plate of the present invention is not limited to these embodiments, and may have any configuration as long as it includes a polarizer and a functional layer laminated on at least one surface of the polarizer.

The " polarizer " in the present invention is a member having a function of converting light such as natural light into linearly polarized light, and has a transmission axis and an absorption axis. The transmission axis direction of the polarizer is understood as a vibration direction of the transmitted light when natural light is transmitted through the polarizer. On the other hand, the absorption axis of the polarizer is orthogonal to the transmission axis of the polarizer. In general, the polarizer may be a stretched film, the absorption axis direction of the polarizer may coincide with the stretching direction MD, and the transmission axis direction of the polarizer may coincide with the width direction TD.

In the present invention, the " functional layer " means a layer formed for the purpose of exerting or imparting any function, e.g., physical, mechanical and / or optical function, to the polarizer. The functional layer may be laminated to the polarizer by any suitable method, and may be bonded to the polarizer by an adhesive, for example.

Such a functional layer includes, for example, a protective film, a retardation film, a brightness enhancement film, and the like, and any of these single layers or any two or more laminated layers may be used. The protective film may be one capable of exhibiting a function of protecting the polarizer, may not have an optical function, or may be one having optical function, such as a retardation film or a brightness enhancement film. A layer such as a hard coating layer, an antireflection layer, or an antiglare layer may be formed on the side opposite to the side where the protective film is adhered to the polarizer. However, the functional layer may be a protective film alone or a laminate of a protective film and a retardation film.

The polarizing plate of the present invention satisfies a value (DELTA E, hereinafter also simply referred to as " elastic modulus difference ") obtained by subtracting the modulus of elasticity of the polarizing element in the transmission axis direction of the functional layer from the modulus of elasticity of the polarizer in the transmission axis direction Satisfies the following formula (1)).

? E = E _P -E _F ? -1100 ... (One)

E _P : modulus of elasticity of the polarizer in the transmission axis direction (MPa)

E _F : modulus of elasticity of the functional layer in the transmission axis direction (MPa)

The term " polarizer transmission axis direction " in the present invention means a direction parallel or substantially parallel to the transmission axis direction of the polarizer (the angle formed is within ± 7 degrees).

When the modulus of elasticity difference E is -1100 MPa or more, crack resistance under an environment in contact with water is improved, and a polarizer excellent in durability is provided. Such a polarizing plate of the present invention can exhibit good polarization characteristics without causing light leakage (light leakage in the case of orthogonal Niccolo observation by a polarization microscope), cracking, etc. even in an environment where condensation occurs. The elastic modulus difference ΔE is more preferably about -1000 MPa or more, and the upper limit is not particularly limited, but may be about 3000 MPa or less, particularly about 2500 MPa or less, preferably about 2,000 MPa or less, more preferably about 1,500 MPa or less .

The modulus of elasticity E _P of the polarizer in the transmission axis direction of the polarizer may be varied depending on the raw material of the polarizer, the manufacturing method, etc., but may be about 3500 to 6000 MPa, preferably 5500 MPa or less, more preferably 5000 MPa or less. The modulus of elasticity E _P of the polarizer in the direction of the transmission axis of the polarizer is preferably larger in order to increase the difference in elastic modulus ΔE = E _P -E _F. On the other hand, from the viewpoint of suppressing a crack that may occur when forming the polarizing plate, it is preferable that the modulus of elasticity E _P of the polarizer in the transmission axis direction is smaller. When the modulus of elasticity E _P in the direction of the polarizer transmission axis of the polarizer is in the above-mentioned range, it becomes easy to make them compatible. For example, in the case of a polarizer obtained by stretching, dyeing, crosslinking in a boric acid solution, etc., a polyvinyl alcohol resin film, the stretching magnification is increased, the boron content in the polarizer is increased, And / or a crosslinking agent other than boric acid such as glyoxal or glutaraldehyde is introduced, the modulus of elasticity of the polarizer in the transmission axis direction can be further increased.

The modulus of elasticity of the polarizer in the direction of the transmission axis of the polarizer is measured as the tensile modulus of elasticity (MPa) of the polarizer in the transmission axis direction of the polarizer at a predetermined temperature (typically 23 deg. More specifically, a test piece is cut from a polarizer, and both ends of the test piece in the polarizer transmission axis direction are held by a tester under a predetermined temperature environment and pulled along the direction of the transmission axis of the polarizer. The initial linear slope .

The modulus of elasticity E _F of the functional layer in the direction of the transmission axis of the polarizer may vary depending on the composition of the functional layer, the presence or absence of optical properties, and the like. For example, in the range of about 1000 to 10000 MPa, the modulus of elasticity E _P , the above expression (1) can be suitably selected. The modulus of elasticity E _F of the functional layer in the direction of the transmission axis of the polarizer is preferably smaller in order to increase the difference in elastic modulus ΔE = E _P -E _F. The present invention is not limited thereto. However, when the functional layer has the orientation property, the degree of orientation is reduced and / or the functional layer is made of a material having a composition which does not have a rigid structure such as a ring structure in the main chain, The modulus of elasticity of the functional layer in the direction of the transmission axis of the polarizer can be further reduced. The " polarizer transmission axis direction " of the functional layer means a direction parallel or substantially parallel to the transmission axis direction of the polarizer (an angle formed within ± 7 degrees) when the functional layer is laminated on the polarizer.

The modulus of elasticity of the functional layer in the direction of the transmission axis of the polarizer is measured as the tensile modulus of elasticity (MPa) of the functional layer in the polarizer transmission axis direction at a predetermined temperature (typically 23 deg. More specifically, the test piece is cut from the functional layer, and both ends of the test piece in the direction parallel to the polarizer transmission axis are held by a tester under a predetermined temperature environment and pulled along the direction of the transmission axis of the polarizer. Can be calculated from the slope.

In the case where the first functional layer 3 and the second functional layer 5 are laminated on both surfaces of the polarizer 1 as shown in Figs. 1 and 2, the polarizer of the present invention has the polarizer- -1100 MPa or more and a value obtained by subtracting the modulus of elasticity of the polarizing element in the transmission axis direction of the second functional layer from the modulus of elasticity of the polarizer in the transmission axis direction Of -1100 MPa or more. In this case, E _F in the formula (1) is a value when the modulus of elasticity of the first functional layer in the direction of the polarizer transmission axis is the same as the modulus of elasticity of the second functional layer in the direction of the transmission axis of the polarizer. It can be represented by any value.

2 and 3, the pressure-sensitive adhesive layer 7 that can be included in the polarizing plate of the present invention (when the release layer is present on the surface thereof, after peeling off the release layer), the polarizing plates 11 and 12 ) To another member.

The elastic modulus of the pressure-sensitive adhesive layer in the direction of the polarizer transmission axis may be 5000 kPa or less, preferably 1000 kPa or less, and accordingly, when the polarizing plate is adhered to a liquid crystal display device or the like through a pressure- It is possible to improve the property. The modulus of elasticity of the pressure-sensitive adhesive layer in the direction of the polarizer transmission axis is more preferably about 500 kPa or less, and further preferably 150 kPa or less. The lower limit of the modulus of elasticity of the pressure-sensitive adhesive layer in the transmission axis direction of the polarizer is not particularly limited, but may be, for example, about 50 kPa or more. The present invention is not limited thereto. For example, by adding an oligomer such as a urethane acrylate oligomer to a known pressure-sensitive adhesive and / or adding a crosslinking agent such as an isocyanate-based crosslinking agent, the pressure- Can be adjusted to the above range. When the modulus of elasticity of the pressure-sensitive adhesive layer in the direction of the transmission axis of the polarizer is within the above range, both the suppression of the dimensional change of the polarizing plate and the relaxation of stress can be easily achieved. The " polarizer transmission axis direction " of the pressure-sensitive adhesive layer means a direction in which the pressure-sensitive adhesive layer is parallel to or substantially parallel to the transmission axis direction of the polarizer when the pressure-sensitive adhesive layer is laminated on the polarizer.

The modulus of elasticity of the pressure-sensitive adhesive layer in the direction of the polarizer transmission axis is measured as tensile modulus (kPa) in the direction of the polarizer transmission axis of the pressure-sensitive adhesive layer at a predetermined temperature (typically 23 deg. More specifically, the test piece is cut from the pressure-sensitive adhesive layer, and both ends of the test piece in the polarizer transmission axis direction are held by a tester under a predetermined temperature environment and stretched along the polarizer transmission axis direction. The initial straight line Can be calculated from the slope.

For example, the polarizing plate 11 can be bonded to the other member 15 through the pressure-sensitive adhesive layer 7 as shown in Fig. 4 to constitute the image display device 20. [ The other member is not particularly limited, but may be, for example, a liquid crystal cell, an organic electroluminescence element, or the like. Typically, a polarizing plate may be bonded to a glass plate constituting these through a pressure-sensitive adhesive layer. The image display device is referred to as a liquid crystal display device in the case of a liquid crystal cell and the organic electroluminescence display device in the case of an organic electroluminescence device. However, the image display device of the present invention is not limited to such an embodiment, and can have any suitable configuration as long as it includes the liquid crystal cell or the organic electroluminescence element and the polarizing plate of the present invention.

Hereinafter, the polarizing plate and the image display apparatus of the present invention will be described in more detail by way of these manufacturing methods.

In order to produce the polarizing plate of the present invention, a polarizer, a functional layer and, if used, an adhesive layer are prepared.

[Polarizer]

The polarizer may be a polyvinyl alcohol resin film which has been subjected to stretching, dyeing, crosslinking in a boric acid solution or the like.

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

The degree of saponification of the polyvinyl alcohol resin may be in the range of 80 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more. The polyvinyl alcohol resin may be a partially modified polyvinyl alcohol, and examples thereof include polyvinyl alcohol resins such as olefins such as ethylene and propylene; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; An alkyl ester of an unsaturated carboxylic acid and an acrylamide. The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 10,000, more preferably 1,500 to 8,000, and still more preferably 2,000 to 5,000.

The polarizer is obtained by, for example, uniaxially stretching a original film made of a polyvinyl alcohol-based resin, swelling it with water (swelling step), dyeing it with a dichroic dye (dyeing step), crosslinking it with an aqueous boric acid solution (Cleaning process), and finally drying (drying process).

The uniaxial stretching of the polyvinyl alcohol-based resin film may be either of dry stretching for stretching in air or wet stretching for stretching in a bath, or both. In order to increase the modulus of elasticity E _P of the polarizer in the direction of the transmission axis of the polarizer, it is preferable to perform wet stretching which is advantageous for improving the stretching magnification. In the wet stretching, for example, the polyvinyl alcohol resin film may be stretched in a state of being immersed in the treatment bath during and / or before and / or during the dyeing step and / or the crosslinking step. In order to perform uniaxial stretching, a polyvinyl alcohol resin film may be stretched by passing between rolls having different circumferences, or may be stretched by sandwiching a polyvinyl alcohol resin film between the rolls. The final draw ratio of the polyvinyl alcohol resin film is usually about 4 to 8 times.

In the swelling process, the polyvinyl alcohol resin film is swollen with water. The swelling treatment can be carried out by immersing the polyvinyl alcohol resin film in water. The temperature of the water is, for example, 10 to 70 占 폚, and the immersion time is, for example, about 10 to 600 seconds.

In the dyeing step, the polyvinyl alcohol resin film is dyed with a dichroic dye, and the dichroic dye is adsorbed to the film. In the dyeing treatment, for example, a polyvinyl alcohol resin film may be immersed in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically iodine or dichromatic dye is used.

When iodine is used as the dichroic dye, a method is generally employed in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide to stain the dye. The content of iodine in the aqueous solution may be about 0.003 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide in the aqueous solution is usually about 0.1 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution is usually about 10 to 45 占 폚, and the immersion time is usually about 30 to 600 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ^{-3 to} 1 part by weight per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 占 폚, and the immersion time is usually about 20 to 600 seconds.

The crosslinking step is carried out, for example, by immersing a dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The content of boric acid in the aqueous solution of boric acid is usually about 1 to 15 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. The content of potassium iodide in the aqueous boric acid solution is usually about 1 to 20 parts by weight, preferably 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time of the film with respect to the aqueous boric acid solution is usually about 10 to 600 seconds, preferably 20 seconds or more, and more preferably 300 seconds or less. The temperature of the boric acid aqueous solution is usually 50 ° C or higher, preferably 50-70 ° C. As the pH adjuster, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid, and the like may be added to the aqueous solution of boric acid. The boric acid aqueous solution may be two or more kinds of which are different in composition and temperature, and in this case, it is preferable that the boric acid aqueous solution after the first aqueous boric acid solution is applied so that the boric acid concentration becomes lower.

The polyvinyl alcohol resin film subjected to the crosslinking step is generally subjected to a washing step with water. The cleaning treatment is performed, for example, by immersing the crosslinked polyvinyl alcohol-based resin film in water. The temperature of the water in the washing treatment is usually about 5 to 40 캜, and the immersing time is usually about 2 to 120 seconds.

Thereafter, a polarizer is obtained through a drying process. Drying is usually carried out using a hot-air dryer or a far-infrared heater. The drying temperature is usually 40 to 100 占 폚, and the drying time is usually 30 to 600 seconds.

The thickness of the polarizer may be, for example, about 5 to 30 탆. The boron content of the polarizer is preferably 1.5% by weight or more, more preferably 2.0% by weight or more, still more preferably 3.0% by weight or more from the viewpoint of obtaining excellent durability, Is preferably 5.5% by weight or less, more preferably 5.0% by weight or less from the viewpoint of curling (curling).

[Functional layer]

The functional layer may be typically a protective film. The protective film may be a transparent resin film composed of a thermoplastic resin. As the thermoplastic resin, for example, a polyolefin-based resin such as a chain-like polyolefin-based resin and a cyclic polyolefin-based resin exemplified by a polypropylene-based resin; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polycarbonate resin; (Meth) acrylic resins selected from polymethylmethacrylate resins; Or a mixture of at least two kinds or more of them. Further, a copolymer of at least two kinds of monomers constituting the resin may be used.

The cyclic polyolefin-based resin is generally a resin that is polymerized using a cyclic olefin as a polymerization unit, and examples thereof include: JP-A-1-240517, JP-A-3-14882, JP-A-3-122137 And resins described in, for example, JP-A-2004-346991. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer (typically a random copolymer) of a chain olefin and a cyclic olefin such as ethylene and propylene, A graft polymer modified with a carboxylic acid or a derivative thereof, and a hydride thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used.

Various products of the cyclic polyolefin resin are commercially available. Examples of commercially available products of the cyclic polyolefin resins include TOPAS (registered trademark), TOPA (registered trademark) sold by TOPAS ADVANCED POLYMERS GmbH, Polyplastics Co., Ltd., Japan, and ATON "Zeonoa" (registered trademark) and "Zeonex" (registered trademark) sold by Nippon Zeon Co., Ltd., and "Apel" (registered trademark) sold by Mitsui Chemical Co., Ltd., and the like.

Further, a commercially available product of the film-formed annular polyolefin-based resin film may be used as a protective film. Examples of commercially available products are all trade names; "Aton film" sold by JSR Corporation ("Aton" is a registered trademark of the company); "Essina" (registered trademark) sold by Sekisui Chemical Co., ZeonoAfilm " (registered trademark) sold by Nippon Zeon Co., Ltd., and the like.

The cellulose ester resin is usually an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, they may be copolymerized with each other or a group in which a part of the hydroxyl group is modified with another substituent may be used. Of these, cellulose triacetate (triacetylcellulose: TAC) is particularly preferable. Many products of cellulose triacetate are commercially available and are advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include all trade names such as "Fuji Takk (registered trademark) TD80", "Fuji Takk (registered trademark) TD80UF", "Fuji Takk (registered trademark) TD80UZ" Fuji TAK (registered trademark) TD40UZ ", and TAC films " KC8UX2M ", " KC2UA ", and " KC4UY " manufactured by Konica Minolta Co.,

The polyester-based resin is a resin other than the cellulose-based resin having an ester bond, and is generally composed of a polycondensation product of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethylterephthalate, dimethyl naphthalenedicarboxylate and the like. As the polyhydric alcohol, a dihydric diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

The polycarbonate resin is an engineering plastic made of a polymer having a monomer unit bonded through a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate resin may be a resin called a modified polycarbonate such as a polymer skeleton modified to lower the photoelastic coefficient, or a copolymerized polycarbonate improved in wavelength dependency.

The (meth) acrylic resin is a polymer containing a constituent unit derived from a (meth) acrylic monomer. The polymer is typically a polymer comprising a methacrylate ester. Preferably, the ratio of the structural units derived from methacrylic acid ester is 50% by weight or more based on the total structural units. The (meth) acrylic resin may be a homopolymer of methacrylic acid ester, or may be a copolymer containing constituent units derived from other polymerizable monomers. In this case, the proportion of the structural units derived from other polymerizable monomers is preferably 50% by weight or less based on the total structural units.

As the methacrylic acid ester which can constitute the (meth) acrylic resin, an alkyl methacrylate ester is preferable. Examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, , 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, and the like. The number of carbon atoms of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, the methacrylic acid ester may be used singly or in combination of two or more kinds.

Examples of the other polymerizable monomer capable of constituting the (meth) acrylic resin include an acrylic acid ester and other compounds having a polymerizable carbon-carbon double bond in the molecule. As the other polymerizable monomers, only one type may be used alone, or two or more types may be used in combination. As the acrylic acid ester, acrylic acid alkyl ester is preferable. Examples of the alkyl acrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, And alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as ethyl. The number of carbon atoms of the alkyl group contained in the alkyl acrylate is preferably 1 to 4. In the (meth) acrylic resin, the acrylic acid ester may be used singly or in combination of two or more kinds.

Other compounds having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene and styrene, and vinyl cyan compounds such as acrylonitrile. The other compounds having a polymerizable carbon-carbon double bond in the molecule may be used singly or in combination of two or more.

As long as it is within the scope of the present invention, the functional layer may be a protective film having optical functions such as a retardation film and a brightness enhancement film. For example, a retardation film having an arbitrary retardation value can be obtained by stretching a transparent resin film made of the above material (such as uniaxial stretching or biaxial stretching) or forming a liquid crystal layer or the like on the film. Alternatively, the functional layer may be a bonded product of a protective film and a retardation film.

The functional layer may be provided with a surface treatment layer (coating layer) such as a hard coating layer, an antiglare layer, an antireflection layer, an antistatic layer and an antifouling layer on the surface opposite to the polarizer of the functional layer. The surface treatment layer can be formed by a known method.

When the first functional layer and the second functional layer are formed on both surfaces of the polarizer, these two functional layers may be the same or different. Examples of the case where the functional layers are different include a combination in which the types of thermoplastic resins constituting the functional layer are at least different from each other; At least different combinations of the presence or absence of the optical function of the functional layer or its kind; At least different combinations of the presence or absence of the surface treatment layer formed on the surface or the like.

The thickness of the functional layer is preferably thin in view of thinning of the polarizing plate, and is, for example, 90 占 퐉 or less, preferably 60 占 퐉 or less, more preferably 50 占 퐉 or less, and further preferably 30 占 퐉 or less. On the other hand, the functional layer preferably has a thickness capable of securing a certain degree of strength from the viewpoint of workability, and is, for example, 5 m or more.

[Pressure sensitive adhesive layer]

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, any conventionally known pressure-sensitive adhesive may be appropriately selected, and any adhesive may be used so long as it does not cause peeling or the like under an environment in which the polarizing plate can be exposed. Specifically, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, rubber pressure-sensitive adhesives, and the like can be mentioned. In view of transparency, weather resistance, heat resistance and workability, acrylic pressure-sensitive adhesives are particularly preferable.

As the pressure-sensitive adhesive, a filler, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, an antistatic agent, a silane coupling agent, and the like made of a tackifier, a plasticizer, a glass fiber, a glass bead, a metal powder, , And various additives may be appropriately blended.

The pressure-sensitive adhesive layer is usually formed by applying a solution of a pressure-sensitive adhesive on a release layer (release film) and drying it. The coating on the release layer may be carried out by 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, a spraying method, or the like. A separate release layer may be provided on the surface of the pressure-sensitive adhesive layer formed by applying a pressure-sensitive adhesive on the release layer, and a release layer may be formed on both surfaces of the pressure-sensitive adhesive layer.

The thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 占 퐉, preferably 5 to 50 占 퐉.

[Production of polarizing plate]

The polarizer, the functional layer and, if used, the pressure-sensitive adhesive layer are laminated in a desired order to produce the polarizing plate of the present invention.

The lamination of the polarizer layer and the functional layer may be carried out by any appropriate method, and for example, an interlayer may be bonded using an adhesive. As the adhesive, an aqueous adhesive, an active energy ray-curable adhesive, a thermosetting adhesive or the like can be used, and from the viewpoint of productivity, it is preferable to use an aqueous adhesive and an active energy ray curable adhesive. The thickness of the adhesive layer in the obtained polarizing plate may be, for example, about 0.01 to 0.2 mu m for an aqueous adhesive, and 0.1 to 4 mu m for an active energy ray curable adhesive.

The water-based adhesive is obtained by dissolving the adhesive component in water or dispersing in water. The water-based adhesive preferably used is, for example, an adhesive composition comprising a polyvinyl alcohol resin or a urethane resin as a main component.

When a polyvinyl alcohol resin is used as the main component of the adhesive, the polyvinyl alcohol resin may be a polyvinyl alcohol resin such as partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, or may be a carboxyl group-modified polyvinyl alcohol, Modified polyvinyl alcohol resins such as acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol and amino group-modified polyvinyl alcohol. The polyvinyl alcohol resin may be a polyvinyl alcohol copolymer obtained by saponifying a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, as well as a copolymer of vinyl acetate and another monomer copolymerizable therewith It may be.

An aqueous adhesive containing a polyvinyl alcohol resin as an adhesive component is usually an aqueous solution of a polyvinyl alcohol resin. The concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of water.

An adhesive composed of an aqueous solution of a polyvinyl alcohol resin may contain a curing component such as a polyvalent aldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal, a glyoxal derivative and a water-soluble epoxy resin or a crosslinking agent . Examples of the water-soluble epoxy resin include epoxy resins obtained by reacting epichlorohydrin with polyamide amines obtained by the reaction of polyalkylene polyamines such as diethylene triamine and triethylene tetramine with dicarboxylic acids such as adipic acid A polyamide polyamine epoxy resin can be suitably used. Examples of commercially available polyamide polyamine epoxy resins include Sumirez Resin 650 (manufactured by Daoka Chemical Industry Co., Ltd.), Sumirez Resin 675 (manufactured by Daoka Chemical Industry Co., Ltd.), WS-525 (Manufactured by Japan PMC Co., Ltd.). The addition amount of these curable components and the crosslinking agent (the total amount when they are added together as the curing component and the crosslinking agent) is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol resin. When the addition amount of the curing component or the crosslinking agent is less than 1 part by weight based on 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesiveness tends to become smaller. When the addition amount is 100 parts by weight of the polyvinyl alcohol resin Is more than 100 parts by weight, the adhesive layer tends to become fragile.

A suitable example of the case where a urethane resin is used as a main component of the adhesive includes a mixture of a polyester-based ionomer-type urethane resin and a compound having a glycidyloxy group. The polyester-based ionomer-type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the urethane resin. Such an ionomeric urethane resin is suitable as an aqueous adhesive since it emulsifies directly by emulsification in water without using an emulsifier.

The active energy ray-curable adhesive is an adhesive which is cured by irradiation with an active energy ray such as ultraviolet rays, visible light, electron rays, and X-rays. When an active energy ray-curable adhesive is used, the adhesive layer of the polarizing plate is a cured layer of the adhesive.

The active energy ray curable adhesive may be an adhesive containing an epoxy compound curable by cationic polymerization as a curable component and is preferably an ultraviolet curable adhesive containing such an epoxy compound as a curable component. The epoxy compound referred to herein means a compound having an average of at least one, preferably two or more epoxy groups in the molecule. The epoxy compound may be used alone or in combination of two or more.

Specific examples of the epoxy compound that can be suitably used include a hydrogenated epoxy compound obtained by reacting epichlorohydrin with an alicyclic polyol obtained by subjecting an aromatic ring of an aromatic polyol to a hydrogenation reaction Cidyl ether); Aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof; And an alicyclic epoxy compound which is an epoxy compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

The active energy ray-curable adhesive may contain, as a curable component, a (meth) acrylic compound that is radically polymerized instead of or in addition to the epoxy compound. Examples of the (meth) acrylic compound include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule; (Meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers obtained by reacting two or more kinds of functional group-containing compounds and having at least two (meth) acryloyloxy groups in the molecule.

When the active energy ray-curable adhesive contains an epoxy compound curable by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the cationic polymerization initiator include aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-allene complexes and the like. Further, when the active energy ray-curable adhesive contains a radically polymerizable curable component such as a (meth) acrylic compound, it preferably contains a photo radical polymerization initiator. Examples of the photo radical polymerization initiator include an acetophenone-based initiator, a benzophenone-based initiator, a benzoin ether-based initiator, a thioxanthone-based initiator, xanthone, fluorenone, camphorquinone, benzaldehyde and anthraquinone.

A surface activation treatment such as a plasma treatment, a corona treatment, an ultraviolet ray irradiation treatment, a flame treatment or a saponification treatment may be performed on the bonding surfaces of the polarizing film and / or the protective film before bonding the protective film to the polarizing film . By this surface activation treatment, the adhesion between the polarizing film and the protective film can be enhanced.

When the pressure-sensitive adhesive layer is used, it can be laminated on the polarizer layer or the functional layer by its own adhesiveness. More specifically, when a release layer is present on the laminate surface of the pressure-sensitive adhesive layer, the release layer may be peeled off and the pressure-sensitive adhesive layer may be laminated to the polarizer layer or the functional layer.

[Manufacturing of Image Display Device]

The polarizing plate produced as described above is bonded to another member (optical member) through the pressure-sensitive adhesive layer to obtain an image display apparatus. More specifically, when a peeling layer is present on the bonding surface of the pressure-sensitive adhesive layer, the peeling layer may be peeled off and the polarizing plate may be bonded to another member by adhesiveness of the pressure-sensitive adhesive layer. For example, a liquid crystal display device can be obtained by bonding a polarizing plate to a liquid crystal cell, and an organic electroluminescence display device can be obtained by bonding to an organic electroluminescence device. A known liquid crystal cell or an organic electroluminescence device to which a polarizing plate is bonded may be applied. A component of the liquid crystal cell or the organic electroluminescence element to which the polarizing plate is directly bonded is typically a glass plate.

However, it should be noted that the use of the polarizing plate of the present invention is not limited to the image display apparatus, but can be used for various optical uses.

Example

≪ Example 1 >

(A) Production of polarizer

(Average degree of polymerization: about 2400, saponification degree: 99.9 mol% or more, thickness: 60 탆) was continuously conveyed and immersed in a swelling bath made of pure water at 20 캜 for a retention time of 31 seconds ). Thereafter, the film drawn out from the swelling bath was immersed in a dyeing bath at 30 DEG C containing iodine with a potassium iodide / water ratio of 2/100 (weight ratio) for a residence time of 122 seconds (dyeing step). Subsequently, the film drawn out from the dyeing bath was immersed in a crosslinking bath at 56 ° C of 12 / 4.1 / 100 (weight ratio) of potassium iodide / boric acid / water at a retention time of 70 seconds. Subsequently, potassium iodide / boric acid / /2.9/100 (weight ratio) in a crosslinking bath at 40 占 폚 for a residence time of 13 seconds (crosslinking step). In the dyeing step and the crosslinking step, longitudinal uniaxial stretching was performed by roll-to-roll stretching in a bath. The total draw ratio based on the original film was set to 5.5 times. Next, the film drawn out from the crosslinking bath was immersed in a washing bath consisting of pure water at 5 占 폚 for a residence time of 3 seconds (cleaning step), introduced into a drying furnace at 80 占 폚 for 190 seconds and dried (drying step) Polarizers were obtained. The thickness of the polarizer obtained in this example was 23.6 占 퐉.

(B) Production of Polarizing Plate

The polarizer obtained in the step (A) was continuously conveyed, and a long first functional layer (first protective film) (TAC film "KC8UX" manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 μm) (TAC film " KC8UX " manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 占 퐉) was successively transferred between the polarizer and the first functional layer and between the polarizer and the second functional layer by using an aqueous adhesive And passed between the bonding rolls to obtain a laminated film composed of the first functional layer / water-based adhesive layer / polarizer / water-based adhesive layer / second functional layer. Subsequently, the obtained laminated film was conveyed, introduced into a drying furnace at 60 占 폚 for a retention time of 100 seconds, and subjected to heat treatment to dry the water-based adhesive layer to obtain a polarizing plate. To the aqueous adhesive, a polyvinyl alcohol aqueous solution having a concentration of 3% by weight obtained by dissolving polyvinyl alcohol powder (trade name "Kosei Piper", average degree of polymerization 1100, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) in hot water at 95 ° C was added with a crosslinking agent (Sodium glyoxylate, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) in an amount of 1 part by weight based on 10 parts by weight of polyvinyl alcohol powder.

(C) Production of a polarizing plate with a pressure-sensitive adhesive layer

A pressure-sensitive adhesive layer having a thickness of 25 占 퐉 was formed on the second functional layer of the polarizing plate obtained in the above-mentioned (B) using a commercially available acrylic pressure-sensitive adhesive sheet formed on the release layer (release film) To prepare a polarizing plate with a pressure-sensitive adhesive layer.

(D) The modulus of elasticity of the polarizer in the transmission axis direction (tensile modulus)

A rectangular test piece having a length of 100 mm in the polarizer transmission axis direction and a width of 20 mm in the polarizer absorption axis direction was cut from the polarizer obtained in the above (A). Then, both ends of the test piece in the longitudinal direction (polarizer transmission axis direction) were sandwiched between the upper and lower grip mechanisms of a tensile tester (Autograph AG-1S tester manufactured by Shimadzu Corporation) (In the direction of the transmission axis of the polarizer) at a tensile rate of 5 mm / min under the environment of a temperature of 25 DEG C and an initial linear slope in the obtained stress-strain curve, the modulus of elasticity of the polarizer in the transmission axis direction (Tensile modulus of elasticity) [MPa] was calculated. The modulus of elasticity E _P of the polarizer in the transmission axis direction of the polarizer of the present example thus calculated was 4773 MPa.

(E) Boron content of the polarizer

Approximately 0.2 g of the polarizer was added to 170 ml of pure water and completely dissolved at 95 ° C, and 30 g of an aqueous mannitol solution (12.5% by weight) was added to prepare a sample solution for measurement. An aqueous sodium hydroxide solution (1 mol / l) was added dropwise until the measurement sample solution reached the neutralization point, and the boron content (% by weight) in the polyvinyl alcohol film was calculated from the drop amount from the following equation. The boron content of the polarizer of the present example thus calculated was 3.8% by weight.

Boron content = 1.08 x sodium hydroxide aqueous solution loading (ml) / weight of polarizing film (g)

(F) The modulus of elasticity of the functional layer in the transmission axis direction (tensile modulus)

A length of 100 mm in the direction parallel to the polarizer transmission axis direction and a width of 20 mm in the direction parallel to the polarizer absorption axis direction were obtained from the first functional layer and the second functional layer used in the production of the polarizer (B) mm < / RTI > Subsequently, the upper and lower grip mechanisms of a tensile tester (Autograph AG-1S tester manufactured by Shimadzu Corporation) were used to sandwich both ends of the test piece in the longitudinal direction (parallel to the direction of the transmission axis of the polarizer) And the test piece was stretched in the longitudinal direction (in the direction parallel to the direction of the polarizer transmission axis) at a tensile rate of 5 mm / min under an environment of 23 ° C. From the initial linear slope in the obtained stress-strain curve, The elastic modulus (tensile elastic modulus) [MPa] of the functional layer in the direction of the polarizer transmission axis was calculated. Accordingly, the calculation of this embodiment first function modulus of the polarizer transmission axis direction of the layer E _F1 and the second function modulus of the polarizer transmission axis direction of the layer E _F2 was 4169 MPa.

(G) The modulus of elasticity of the pressure-sensitive adhesive layer in the direction of the polarizer transmission axis (tensile modulus of elasticity)

From the pressure-sensitive adhesive sheet used for producing the polarizing plate with a pressure-sensitive adhesive layer (C) above, only the pressure-sensitive adhesive layer was formed in a thickness of 50 mm in the direction parallel to the polarizer- mm < / RTI > Then, the upper and lower grip mechanisms of a precision universal testing machine (Autograph AGS-50NX tester manufactured by Shimadzu Corporation) were used to sandwich both ends of the test piece in the longitudinal direction (parallel to the direction of the transmission axis of the polarizer) And the test piece was stretched in the longitudinal direction (in a direction parallel to the direction of the polarizer transmission axis) at a tensile rate of 300 mm / min under an environment of 23 캜. From the initial linear slope in the obtained stress-strain curve, (Tensile elastic modulus) [kPa] of the pressure-sensitive adhesive layer in the direction of the polarizer transmission axis was calculated. The elastic modulus E _PSA of the pressure-sensitive adhesive layer thus calculated in the direction of the polarizer transmission axis was 135 kPa.

(H) Modulus difference

From the modulus of elasticity E _P of the polarizer in the transmission axis direction of the polarizer obtained in (D) above, the modulus of elasticity E _F1 of the first functional layer obtained in (F) above in the polarizer transmission axis direction and the transmittance When the elastic modulus E _F2 in the axial direction is the same, the value is calculated. When the elastic modulus E _F2 in the axial direction is different, the larger value is subtracted as E _F. The elastic modulus difference E of the present example thus calculated was 604 MPa.

(I) Evaluation of crack resistance

A rectangular test piece having a length of 80 mm in the polarizer transmission axis direction and a width of 60 mm in the polarizer absorption axis direction was cut from the polarizing plate with a pressure-sensitive adhesive layer obtained in the above (C). The test pieces were bonded to a glass plate and placed in an oven at 80 ° C for 1 hour. The test piece bonded to the glass plate was taken out from the oven and then stored at 23 캜 for 15 minutes under an environment of 55% relative humidity and then immersed in water at 23 캜 for 30 minutes. After the test piece bonded to the glass plate was taken out from the water, the moisture of the test piece was removed by air blowing. Thereafter, the end portion of the test piece in the longitudinal direction (direction of the transmission axis of the polarizer) was visually observed using a magnifying glass (magnification: 10 times) to count the number of cracks. Cracks were not seen in this embodiment.

≪ Examples 2 to 4 &

A polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced in the same manner as in Example 1, except that the first functional layer and the second functional layer in the production of the polarizing plate were changed as shown in Table 1. The abbreviations of the functional layers in Table 1 are as follows.

[A] TAC1: TAC film "K8UX2MW" manufactured by Konica Minolta Opto Co., Ltd. Thickness 80 μm

[B] TAC2: TAC film "KC4UYW" manufactured by Konica Minolta Opto Co., Ltd. Thickness 40 μm

[C] TAC3: TAC film "K2UAW" manufactured by Konica Minolta Opto Co., Ltd. Thickness 25 μm

[D] COP1: a trade name "ATON FILM FEKB015D3", a cyclic polyolefin based resin film manufactured by JSR Corporation, having a thickness of 15 μm

[E] COP2: a trade name "Zeonoiafilm ZF14-023", which is a cyclic polyolefin-based resin film manufactured by Nippon Zeon Co., Ltd. Thickness 23 μm

[F] COP3: a trade name " Zeonoa Film ZT12-090079 ", which is a cyclic polyolefin-based resin film manufactured by Nippon Zeon Co., Ltd., thickness 21 mu m, in-plane retardation 90 nm,

≪ Example 5, Comparative Examples 1 to 3 >

The polarizer was immersed in a crosslinking bath at 56 DEG C in which potassium iodide / boric acid / water was 12 / 1.5 / 100 (weight ratio) at a retention time of 70 seconds and then potassium iodide / boric acid / Except that the first functional layer and the second functional layer when the polarizing plate was produced were immersed in a crosslinking bath at 40 DEG C (weight ratio) at a retention time of 13 seconds (crosslinking step) In the same manner, a polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced.

≪ Example 6 >

The polarizer was immersed in a crosslinking bath at 56 deg. C at a weight ratio of 12 / 5.0 / 100 (potassium iodide / boric acid / water) at a residence time of 70 seconds, and then potassium iodide / boric acid / Except that the first functional layer and the second functional layer when the polarizing plate was produced were immersed in a crosslinking bath at 40 DEG C (weight ratio) at a retention time of 13 seconds (crosslinking step) In the same manner, a polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced.

≪ Example 7 >

(Average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more, thickness: 30 탆) was used as the first functional layer and the second functional layer in the production of the polarizing plate as shown in Table 1 A polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced in the same manner as in Example 1. [

≪ Example 8 >

A polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced in the same manner as in Example 7 except that the total stretching ratio on the basis of the original film when the polarizer was produced was adjusted to 5.4 times.

≪ Example 9 >

The polarizer was immersed in a crosslinking bath at 56 DEG C in which potassium iodide / boric acid / water was 12 / 1.5 / 100 (weight ratio) at a retention time of 70 seconds and then potassium iodide / boric acid / Except that the first functional layer and the second functional layer at the time of producing the polarizing plate were immersed in a crosslinking bath at 40 DEG C (weight ratio) at a retention time of 13 seconds (crosslinking step) In the same manner, a polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced.

≪ Comparative Example 4 &

A polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer were produced in the same manner as in Example 9, except that the first functional layer and the second functional layer in the production of the polarizing plate were changed as shown in Table 1.

The conditions and the results of the respective examples and comparative examples are summarized in Table 1.

With reference to Table 1, in Examples 1 to 9, in which the modulus of elasticity difference? E was -1100 MPa or more, the number of cracks was 20 or less, and in Comparative Examples 1 to 4 where the modulus difference ΔE was -1200 MPa or less, , And it was confirmed that it was remarkably reduced.

≪ Examples 10 to 13 &

A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1 or 6 except that a pressure-sensitive adhesive layer having a thickness of 25 占 퐉 was formed on the second functional layer of the polarizing plate using a commercially available acrylic pressure-sensitive adhesive sheet different from that used in Example 1 did. Table 2 shows the elastic modulus E _PSA of each pressure-sensitive adhesive layer in the direction of the polarizer transmission axis.

Conditions and results of the respective examples are summarized in Table 2.

The polarizing plate of the present invention can be used in various optical applications, and can be widely used as, for example, a polarizing light supplying element in an image display apparatus and also as a polarizing light detecting element.

1: Polarizer
3, 5: functional layer
7: Pressure-sensitive adhesive layer
10, 11, 12: polarizer
15: other member (for example, liquid crystal cell, organic electroluminescence element, etc.)
20: Image display device

Claims (9)

A polarizing plate comprising a polarizer and a functional layer laminated on at least one surface of the polarizer, wherein a value obtained by subtracting the modulus of elasticity of the polarizing element in the transmission axis direction of the functional layer from the modulus of elasticity of the polarizer in the transmission axis direction is -1100 MPa or more and 1668 MPa or less. The polarizing plate according to claim 1, wherein the functional layer comprises a protective film. The polarizer according to claim 1 or 2, wherein the functional layer comprises a retardation film. The polarizer according to claim 1 or 2, wherein a functional layer is laminated on one side of the polarizer, and a pressure-sensitive adhesive layer is laminated on the other side of the polarizer. The polarizing plate according to claim 1 or 2, wherein a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer or a release layer is laminated on the surface on one side of the polarizing plate. The polarizing plate according to claim 4, wherein the pressure-sensitive adhesive layer has a modulus of elasticity of 50 kPa or more and 1000 kPa or less in the direction of transmission axis of the polarizer. The polarizing plate according to claim 5, wherein the pressure-sensitive adhesive layer has a modulus of elasticity of 50 kPa or more and 1000 kPa or less in a polarizer transmission axial direction. The polarizing plate according to claim 1 or 2, wherein a value obtained by subtracting the modulus of elasticity of the polarizer in the transmission axis direction of the functional layer from the modulus of elasticity of the polarizer in the transmission axis direction is 1500 MPa or less. An image display device comprising a liquid crystal cell or an organic electroluminescence element and the polarizing plate according to claim 1 or 2.

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