TWI604234B - Polarizing plate and image display device - Google Patents

Description

Polarizer and image display device

The present invention relates to polarizing plates that can be used in a variety of optical applications. Further, the present invention relates to an image display device having the polarizing plate.

A polarizing plate is widely used as a supply element for polarized light in an image display device, and a polarizing detecting element. In such a polarizing plate, for example, a polarizing element obtained by stretching, dyeing, crosslinking, or the like is applied to a polyvinyl alcohol-based resin film. When a polarizing element is cracked, it may cause appearance defects and an optical defect called "light leakage". Conventionally, in order to prevent the occurrence of cracks in the polarizing element, various proposals have been made (see Patent Documents 1 to 5).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-72951

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2012-145645

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-221278

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2004-29367

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2004-20830

Cracks in polarizing elements can occur for a variety of reasons. The representative ones are caused by the intense temperature change (heating) of the surrounding environment exposed to the product, and the crack is generated by heat shock. For example, it will be at -40 °C. The test is repeated 20 times with a thermal cycle between 85 ° C (Patent Document 2), or a test in which the thermal cycle between -35 ° C and 85 ° C is repeated 500 times (Patent Document 4), and crack generation can be evaluated. Degree. In the production process, the protective film is transferred to a polarizing laminated film including a base film, a laminate, and a polarizing element layer which is formed thereon (Patent Document 3), or The force (physical/mechanical squeezing) applied by the polarizing plate cutting process of the polarizing element (patent document 4) causes cracks to occur, and in this case, the degree of cracking can be confirmed after the operations.

In contrast, the inventors of the present invention have focused on the occurrence of cracks due to condensation which may occur during use of the product. Since coagulation causes contact with water, it is considered to be caused by cracking due to a mechanism different from that produced by heat rushing or physical/mechanical rinsing as described above.

It is an object of the present invention to provide a polarizing plate which improves crack resistance in an environment in contact with water.

As a result of research by the inventors of the present invention, a polarizing plate including a polarizing element and a functional layer laminated on at least one side thereof is bonded to the glass. The sample formed by the plate was subjected to a crack-promoting test (including immersion in water), and it was clearly found that the crack was generated from the end face of the polarizing element along the side of the penetrating axis toward the direction of the absorption axis. Moreover, the inventors of the present invention have obtained the unique knowledge that the functional layer laminated on at least one side of the polarizing element has a smaller elastic modulus of the polarizing element in the axial direction, and is more difficult in an environment in contact with water. Cracks are generated, and the greater the difference between the elastic modulus of the direction of the transmission axis of the polarizing element and the elastic modulus of the polarizing element of the functional layer in the direction of the axis of penetration, the more difficult it is to generate cracks in an environment in contact with water, Further intensive studies have led to the completion of the present invention.

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

[1] A polarizing plate comprising a polarizing element and a functional layer laminated on at least one surface of the polarizing element, wherein a polarization modulus of the polarizing element from the polarizing element penetrates the axial direction minus a function of the polarizing element of the functional layer The value after the elastic modulus of the direction is -1100 MPa or more.

[2] The polarizing plate of [1], wherein the functional layer comprises a protective film.

[3] The polarizing plate of [1] or [2], wherein the functional layer comprises a retardation film.

[4] The polarizing plate according to any one of [1] to [3] wherein the polarizing element has a functional layer in one area layer and the other layer of the polarizing element has an adhesive layer.

[5] The polarizing plate according to any one of [1] to [4], wherein the outermost layer of one surface side of the polarizing plate has an adhesive layer or an adhesive layer with a release layer.

[6] The polarizing plate according to [4], wherein the polarizing element of the adhesive layer has an elastic modulus in the axial direction of 1000 kPa or less.

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

According to the present invention, it is possible to provide a polarizing plate which improves crack resistance in an environment in contact with water. Moreover, according to the present invention, an image display device having the polarizing plate can be provided. The polarizing plate and the image display device of the present invention can exhibit high crack resistance to condensation.

1‧‧‧Polarized elements

3, 5‧‧‧ functional layer

7‧‧‧Adhesive layer

10, 11, 12‧ ‧ polarizing plates

15‧‧‧Other components (such as liquid crystal cells, organic electroluminescent elements, etc.)

20‧‧‧Image display device

Fig. 1 is a schematic cross-sectional view showing a polarizing plate in an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing a polarizing plate in another embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a polarizing plate in another embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing an image display device according to an embodiment of the present invention.

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

The polarizing plate of the present invention comprises a polarizing element and a functional layer laminated on at least one surface of the polarizing element. For example, in one embodiment of the present invention, as shown in FIG. 1, the polarizing plate 10 may include the polarizing element 1 and the first functional layer 3 and the second functional layer 5 which are laminated on both surfaces thereof. The polarizing plate of the present invention may further have at least one functional layer on the surface on one side thereof, for example, the polarizing plate 11 shown in FIG. 2 (the second in the illustrated aspect) The functional layer 5) is an area layer adhesive layer 7 on the opposite side to the polarizing element 1, and the adhesive layer 7 may have a release layer (not shown) or no release layer at the outermost surface. In another embodiment of the present invention, as shown in FIG. 3, the polarizing plate 12 may be a functional layer 3 including a polarizing element 1 laminated on one surface thereof, and an adhesive layer 7 laminated on the other surface of the polarizing element 1. . However, the configuration (layering order, etc.) of the polarizing plate of the present invention is not limited to the embodiments, and may include any configuration as long as it includes a polarizing element and a functional layer laminated on at least one surface of the polarizing element.

The "polarizing element" in the present invention has a function of converting light such as natural light into a linearly polarized light, and has a transmission axis and an absorption axis. The direction of the transmission axis of the polarizing element can be understood as the direction of vibration of the transmitted light when natural light penetrates the polarizing element. On the other hand, the absorption axis of the polarizing element is orthogonal to the transmission axis of the polarizing element. Further, the general polarizing element may be a stretched film, and the absorption axis direction of the polarizing element may coincide with the extending direction (MD) thereof, and the transmission axis direction of the polarizing element may coincide with the width direction (TD).

In the present invention, the term "functional layer" means a layer provided for the purpose of exerting or imparting a function to a polarizing element, for example, physical, mechanical, and/or optical functions. The functional layer is laminated on the polarizing element by any suitable method, for example, an adhesive can be used to follow the polarizing element.

The functional layer includes, for example, a protective film, a retardation film, a brightness enhancement film, and the like, and may be any one of the above single layers or any two or more laminated bodies. The protective film may have a function of protecting the polarizing element, and may have an optical function or an optical function, and may be used as a phase. A function of a disparity film or a brightness enhancement film. Further, a layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be formed on the opposite side of the protective film from the side opposite to the polarizing element. The functional layer may be a separate protective film, or may be a bonded product of a protective film and a retardation film, and the like.

The polarizing plate of the present invention satisfies the value of the elastic modulus of the polarization direction of the polarizing element of the polarizing element minus the elastic modulus of the polarizing element of the functional layer in the axial direction (ΔE, hereinafter simply referred to as "elastic modulus" The difference ") is -1100 MPa or more (that is, the following formula (1) is satisfied).

△E=E _P -E _F ≧-1100. . . (1)

E _P : elastic modulus of the polarizing element of the polarizing element in the axial direction (MPa)

E _F : elastic modulus of the polarizing element of the functional layer in the axial direction (MPa)

The term "polarizing element transmission axis direction" in the present invention means a direction parallel or slightly parallel to the direction of the transmission axis of the polarizing element (the angle of the sandwiched member is within ±7 degrees).

By setting the above-described elastic modulus difference ΔE to -1100 MPa or more, it is possible to provide a polarizing plate which improves the crack resistance in an environment of contact with water and has excellent durability. The polarizing plate of the present invention exhibits good polarization characteristics even if it does not leak light (light leakage when observed by a polarizing microscope under orthogonal polarized light), cracking or the like in an environment where condensation occurs. The elastic modulus difference ΔE is preferably about -1000 MPa or more, and the upper limit thereof is not particularly limited, and may be, for example, about 3,000 MPa or less, particularly preferably about 2,500 MPa or less, preferably 2,000 MPa or less, and more preferably 1,500 MPa or less. .

The elastic modulus EP of the polarizing element that penetrates the axial direction of the polarizing element differs depending on the material and the manufacturing method of the polarizing element, but may be, for example, about 3,500 to 6,000 MPa, preferably 5,500 MPa or less, and more preferably 5,000 MPa or less. In order to increase the elastic modulus difference ΔE = E _{P -} E _F , the elastic modulus E _{P of the} polarizing element of the polarizing element in the axial direction is preferably larger. On the other hand, from the viewpoint of suppressing cracks which may occur during the forming process of the polarizing plate, the elastic modulus E _{P of the} polarizing element of the polarizing element in the axial direction is preferably smaller. When the elastic modulus E _P of the polarizing element of the polarizing element in the axial direction is in the above range, both of them can be easily combined. In the polarizing element obtained by stretching, dyeing, or crosslinking in a boric acid solution, for example, when the polyvinyl alcohol-based resin film is applied, the stretching ratio is increased, and boron in the polarizing element is increased. The content ratio and/or introduction of a crosslinking agent other than boric acid such as glyoxal or glutaraldehyde can further increase the elastic modulus of the polarizing element of the polarizing element in the axial direction.

The elastic modulus of the polarizing element of the polarizing element in the axial direction is measured as a tensile elastic modulus (MPa) in the direction of the transmission axis of the polarizing element of the polarizing element at a predetermined temperature (typically 23 ° C). More specifically, the test piece is cut out from the polarizing element, and the polarizing element of the test piece is sandwiched at both end portions in the axial direction by a testing machine under a predetermined temperature environment, and stretched along the axis of the polarizing element. Thereby, the elastic modulus can be calculated from the slope of the initial straight line in the obtained stress-strain curve.

The elastic modulus E _F of the polarizing element of the functional layer that penetrates the axial direction differs depending on the composition of the functional layer, the presence or absence of the optical characteristic, or the like, but in order to respond to the elastic modulus EP of the polarizing element of the polarizing element in the axial direction. The above formula (1) is satisfied, and can be appropriately selected, for example, from the range of about 1,000 to 10,000 MPa. In order to increase the elastic modulus difference ΔE = E _{P -} E _F , the elastic modulus E _F of the polarizing element of the functional layer in the axial direction is preferably smaller. Although the present invention is not limited, when the functional layer has an alignment property, the functional layer can be further reduced by reducing the degree of alignment and/or forming a functional layer by using a material having a rigid structure such as a ring structure in the main chain. The polarizing element penetrates the elastic modulus of the axial direction. In addition, the "polarizing element penetrates the axial direction" of the functional layer, when the functional layer is laminated on the polarizing element, means parallel or slightly parallel to the direction of the transmission axis of the polarizing element (the angle of the sandwiched layer is within ±7 degrees) ) The direction.

The elastic modulus of the polarizing element of the functional layer in the axial direction is measured as the tensile elastic modulus (MPa) of the polarizing element in the axial direction of the functional layer at a predetermined temperature (typically 23 ° C). More specifically, the test piece is cut out from the functional layer, and the polarizing element of the test piece is sandwiched at both end portions in the axial direction by a testing machine under a predetermined temperature environment, and stretched along the direction of the transmission axis of the polarizing element. Thereby, the elastic modulus can be calculated from the slope of the initial straight line in the obtained stress-strain curve.

As shown in FIGS. 1 and 2, when the first functional layer 3 and the second functional layer 5 are laminated on both surfaces of the polarizing element 1, the polarizing plate of the present invention satisfies the polarization axis of the polarizing element. The value of the elastic modulus minus the elastic modulus of the polarizing element of the first functional layer in the direction of the axis of penetration is -1100 MPa or more, and the elastic modulus of the polarizing element of the polarizing element penetrates the axial direction minus the second functional layer. The value after the polarization element penetrates the elastic modulus in the axial direction is -1100 MPa or more. In this case, E _F in the above formula (1) may be the same as the elastic modulus of the polarization direction of the polarizing element of the first functional layer and the elastic modulus of the polarization element of the second functional layer. This value, if not the same, is represented by the value of the larger of them.

As shown in FIGS. 2 and 3, the adhesive layer 7 which can be included in the polarizing plate of the present invention (after peeling of the peeling layer in the presence of the peeling layer) can be used to make the polarizing plates 11, 12 and Other component fitters.

The elastic modulus of the polarizing element of the adhesive layer in the axial direction may be 5000 kPa or less, preferably 1000 kPa or less, whereby the polarizing plate may be in contact with water when the polarizing plate is bonded to the liquid crystal display device or the like through the adhesive layer. The crack resistance in the environment is effectively improved. The elastic modulus of the polarizing element of the adhesive layer in the axial direction is preferably about 500 kPa or less, and more preferably 150 kPa or less. The lower limit of the elastic modulus of the polarizing element of the adhesive layer in the axial direction is not particularly limited, and may be, for example, about 50 kPa or more. The present invention is not limited, but an adhesive such as an oligomer such as a polyurethane acrylate oligomer and/or an isocyanate crosslinking agent may be added to a known adhesive to form an adhesive layer. The elastic modulus of the polarizing element in the axial direction is adjusted to the above range. When the elastic modulus of the polarizing element of the adhesive layer in the axial direction is in the above range, it is possible to easily suppress the dimensional change of the polarizing plate and to alleviate the stress. Further, the "polarizing element penetrating axis direction" of the adhesive layer, when the adhesive layer is laminated on the polarizing element, means parallel or slightly parallel to the direction of the transmission axis of the polarizing element (the angle of the sandwich is ±7) In the direction of the degree).

The modulus of elasticity of the polarizing element of the adhesive layer in the axial direction is measured as the tensile elastic modulus (kPa) of the polarizing element in the direction of the axis of penetration of the adhesive layer at a predetermined temperature (typically 23 ° C). . More detailed In other words, the test piece is cut out from the adhesive layer, and the polarizing element of the test piece is sandwiched at both ends in the axial direction by a testing machine under a predetermined temperature environment, and is stretched along the axis of the polarizing element. The modulus of elasticity can be calculated from the slope of the initial straight line in the resulting stress-strain curve.

As shown in FIG. 4, for example, the polarizing plate 11 can be bonded to the other members 15 through the adhesive layer 7, thereby constituting the image display device 20. The other member is not particularly limited, and may be, for example, a liquid crystal cell or an organic electric field light-emitting device. As a representative, a polarizing plate may be bonded to the glass plate constituting the same through an adhesive layer. The image display device is referred to as a liquid crystal display device in the case of a liquid crystal cell, and is referred to as an organic electric field light-emitting display device in the case of an organic electric field light-emitting device. However, the image display device of the present invention is not limited to this embodiment, and may have any suitable configuration as long as it includes a liquid crystal cell, an organic electroluminescent device, and the polarizing plate of the present invention.

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

In order to manufacture the polarizing plate of the present invention, a polarizing element, a functional layer, and an adhesive layer used depending on the occasion are prepared.

[Polarizing element]

The polarizing element can be obtained by applying a stretching, dyeing, crosslinking in a boric acid solution, or the like to a polyvinyl alcohol-based resin film.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin can be used for saponification. The polyvinyl acetate-based resin may be a copolymer of ethyl acetate and another monomer copolymerizable with the ethyl acetate in addition to the polyvinyl acetate which is a homopolymer of ethyl acetate. As can be used with acetic acid Examples of the other monomer copolymerized with the ester include an unsaturated carboxylic acid, an olefin, a vinyl ether, an unsaturated sulfonic acid, and an acrylamide having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin may be in the range of 80 mol% or more, and is preferably 90 mol% or more, and more preferably 95 mol% or more. The polyvinyl alcohol-based resin may be a part of the modified modified polyvinyl alcohol, and examples thereof include a polyvinyl alcohol-based resin modified by an olefin such as ethylene or propylene; acrylic acid, methacrylate, and 2-butene. An unsaturated carboxylic acid such as an acid; an alkyl ester of an unsaturated carboxylic acid; and acrylamide. The average degree of polymerization of the polyvinyl alcohol-based resin is preferably from 100 to 10,000, more preferably from 1,500 to 8,000, still more preferably from 2,000 to 5,000.

The polarizing element can be cross-linked (crosslinked) with a boric acid aqueous solution by, for example, stretching a germplasm membrane made of a polyvinyl alcohol-based resin in a shaft, swelling it with water (swelling step), dyeing with a dichroic dye (dyeing step), and boric acid aqueous solution. Step), washing with water (washing step), and finally drying (drying step).

The one-axis extension of the polyvinyl alcohol-based resin film may be either a dry extension extending in the air or a wet stretching extending in a water bath, or both. In order to increase the elastic modulus E _{P of the} polarizing element of the polarizing element in the axial direction, it is preferable to carry out the wet extension which is advantageous for increasing the stretching ratio. The wet stretching system can be stretched, for example, in a state where the polyvinyl alcohol-based resin film is immersed in the treatment bath between and/or before and after the dyeing step and/or the crosslinking step. When the one-axis stretching is carried out, the polyvinyl alcohol-based resin film may be stretched between rolls having different circumferential rotation speeds or by a method of sandwiching the polyvinyl alcohol-based resin film with a hot roll. The final stretching ratio of the polyvinyl alcohol-based resin film is usually about 4 to 8 times.

In the swelling step, the polyvinyl alcohol-based 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 ° C, and the immersion time is, for example, about 10 to 600 seconds.

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

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide is usually used for dyeing. The content of iodine in the aqueous solution may usually be from about 0.003 to about 1 part by weight per 100 parts by weight of water. The content of potassium iodide in the aqueous solution may usually be from 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 ° C, 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-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye and dyed is usually used. The content of the dichroic dye in the aqueous solution is usually from about 1 × 10 ^-3 to about 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 ° C, and the immersion time is usually about 20 to 600 seconds.

Cross-linking step is, for example, dyed polyvinyl alcohol tree The lipid film is immersed in an aqueous boric acid solution. The content of boric acid in the aqueous boric acid solution is usually from about 1 to 15 parts by weight, preferably from 2 to 10 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the aqueous boric acid solution is usually from about 1 to 20 parts by weight, preferably from 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time of the film in the aqueous boric acid solution is usually about 10 to 600 seconds, preferably 20 seconds or more, and preferably 300 seconds or less. The temperature of the aqueous boric acid solution is usually 50 ° C or higher, preferably 50 to 70 ° C. Sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid or the like may be added to the aqueous boric acid solution as a pH adjuster. In the boric acid aqueous solution, two or more kinds of different compositions and temperatures can be used. In this case, it is preferred to apply the boric acid concentration of the subsequent boric acid aqueous solution to a lower concentration of boric acid in the boric acid aqueous solution.

The polyvinyl alcohol-based resin film which has undergone the crosslinking step is usually subjected to a washing step by using water. The washing treatment is performed, for example, by immersing the crosslinked polyvinyl alcohol resin film in water. The temperature of the water during the washing treatment is usually about 5 to 40 ° C, and the immersion time is usually about 2 to 120 seconds.

Thereafter, a polarizing element is obtained through a drying step. Drying is usually carried out using a hot air dryer or a far infrared heater. The drying temperature is usually from 40 to 100 ° C, and the drying time is usually from about 30 to 600 seconds.

The thickness of the polarizing element may be, for example, about 5 to 30 μm. The boron content of the polarizing element is preferably 1.5% by weight or more, more preferably 2.0% by weight or more, still more preferably 3.0% by weight from the viewpoint of obtaining excellent durability. From the viewpoint of suppressing shrinkage or curling (warpage) of the polarizing plate due to temperature change, it is preferably 5.5% by weight or less, more preferably 5.0% by weight or less.

[functional layer]

A representative layer of the functional layer may be a protective film. The protective film may be a transparent resin film composed of a thermoplastic resin. Examples of the thermoplastic resin include a polyolefin resin such as a chain polyolefin resin and a cyclic polyolefin resin, and a fiber such as cellulose triacetate or cellulose diacetate. Polyester resin; polyester resin such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resin; polymethyl methacrylate resin The selected (meth)acrylic resin; or a mixture of at least two or more of these. Further, a copolymer constituting at least two kinds of monomers of the above resins may also be used.

The cyclic polyolefin-based resin is a general term for a resin which is polymerized by using a cyclic olefin as a polymerization unit. For example, JP-A-1-240517, JP-A-3-14882, and JP-A 3-122137 The resin described in the Gazette. 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, and a copolymer of a chain olefin such as ethylene or propylene and a cyclic olefin ( Representative of these are random copolymers), and such graft polymers modified with unsaturated carboxylic acids or derivatives thereof, and such hydrides. Among them, a norbornene-based resin using a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is suitably used.

The cyclic polyolefin resin has various commercially available products. Take The product name of the product of the cyclic polyolefin resin is "TOPAS" (registered trademark) manufactured by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. in Japan, and JSR Co., Ltd. "Arton" (registered trademark) sold by the company, "Zeonor" (registered trademark) and "Zeonex" (registered trademark) sold by Japan ZEON Co., Ltd., and "Apel" (registered trademark) sold by Mitsui Chemicals Co., Ltd. )Wait.

Further, a commercially available product of a film-formed cyclic polyolefin resin film can be used as the protective film. As an example of a commercial item, "Arton film" sold by JSR Co., Ltd. ("Arton" is a registered trademark of the same company), "Esushina" sold by Sekisui Chemical Industry Co., Ltd. (registered trademark) and "SCA40", "Zeonor film" (registered trademark) sold by Japan ZEON Co., Ltd., etc.

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, those obtained by copolymerization or a part of a hydroxyl group may be modified by other substituents. Among these, cellulose triacetate (cellulose triacetate: TAC) is particularly preferred. Cellulose triacetate has many commercially available products and is advantageous from the standpoint of ease of availability or cost. As an example of a commercial product of cellulose triacetate, "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered) are sold by Fujifilm Co., Ltd. Trademark) TD80UZ" and "Fujitac (registered trademark) TD40UZ", TAC film manufactured by Konica Minolta Co., Ltd. "KC8UX2M", "KC2UA" and "KC4UY".

The polyester resin is a resin other than the above cellulose resin having an ester bond, and generally includes a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. A divalent carboxylic acid or a derivative thereof can be used as the polyvalent carboxylic acid or a derivative thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylate. . As the polyol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, diol, neopentyl glycol, and cyclohexane dimethanol. Examples of suitable polyester resins include polyethylene terephthalate.

The polycarbonate resin is an engineering plastic composed of a polymer in which a monomer unit is bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. In order to lower the photoelastic coefficient, the polycarbonate resin may be a resin called a modified polycarbonate such as a modified polymer backbone, or a wavelength-dependent modified copolymerized polycarbonate.

The (meth)acrylic resin contains a polymer derived from a constituent unit of a (meth)acrylic monomer. Typical of the polymer is a polymer containing methacrylate. It is preferably a polymer containing a structural unit derived from methacrylate in an amount of 50% by weight or more based on the total structural unit. The (meth)acrylic resin may be a homopolymer of methacrylate or a copolymer containing constituent units derived from other polymerizable monomers. In this case, the ratio of the constituent units derived from the other polymerizable monomer is preferably 50% by weight or less based on the total structural unit.

Methyl acrylate which can constitute a (meth)acrylic resin The ester is preferably an alkyl methacrylate. Examples of the methacrylate alkyl ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate. An alkylene group having a carbon number of 1 to 8 such as a third butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate or 2-hydroxyethyl methacrylate. Base ester. The number of carbon atoms of the alkyl group contained in the alkyl methacrylate is preferably from 1 to 4. In the (meth)acrylic resin, the methacrylate may be used alone or in combination of two or more.

Examples of the other polymerizable monomer which can constitute the (meth)acrylic resin include acrylates and other compounds having a polymerizable carbon-carbon double bond in the molecule. The other polymerizable monomers may be used alone or in combination of two or more. The acrylate is preferably an alkyl acrylate. Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, and 2-ethylhexyl acrylate. An alkyl acrylate having a carbon number of 1 to 8 such as an alkyl group such as cyclohexyl acrylate or 2-hydroxyethyl acrylate. The number of carbon atoms of the alkyl group contained in the alkyl acrylate is preferably from 1 to 4. In the (meth)acrylic resin, the acrylate may be used alone or in combination of two or more.

Other compounds having a polymerizable carbon-carbon double bond in the molecule include a vinyl compound such as ethylene, propylene or styrene, or an ethylene cyanide compound such as acrylonitrile. Other compounds having a polymerizable carbon-carbon double bond in the molecule may be used alone or in combination of two or more.

As long as it is within the scope of the invention, the functional layer can also be phase A protective film that has an optical function, such as a differential film or a brightness enhancement film. For example, a transparent resin film made of the above material may be stretched (one-axis extension or biaxial stretching, or the like), or a liquid crystal layer or the like may be formed on the film, whereby a retardation film having an arbitrary retardation value may be formed. Further, the functional layer may be a laminate of a protective film and a retardation film.

Further, the functional layer may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer on the surface opposite to the polarizing element 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 provided on both surfaces of the polarizing element, the two functional layers may be identical or different from each other. In the case where the functional layers are different, the type of the thermoplastic resin constituting the functional layer is at least a different combination; the presence or absence of the optical function of the functional layer or a combination thereof is at least a different combination; The presence or absence of the surface treatment layer or the kind thereof is at least a combination of the differences.

From the viewpoint of thinning of the polarizing plate, the thickness of the functional layer is preferably thin, for example, 90 μm or less, preferably 60 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less. On the other hand, from the viewpoint of workability, the functional layer is preferably one having a thickness capable of ensuring a certain degree of strength, and is, for example, 5 μm or more.

[adhesive layer]

As the adhesive for forming the pressure-sensitive adhesive layer, any conventionally known one may be used as long as it is an adhesive which does not cause peeling or the like in an environment in which the polarizing plate is exposed. Specifically, propylene is exemplified An acid-based adhesive, a polyoxygen-based adhesive, a rubber-based adhesive, and the like are particularly preferable from the viewpoints of transparency, weather resistance, heat resistance, and workability.

Adhesives, plasticizers, glass fibers, glass beads, metal powders, fillers composed of other inorganic powders, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, etc. may be appropriately blended as needed in the adhesive. Various additives such as antistatic agents and decane coupling agents.

The adhesive layer is usually formed by applying a solution of an adhesive to a release layer (release film) and drying it. The coating on the release layer may be, for example, a roll coating method such as a reverse coating method or a gravure coating method, a notch wheel coating method, a screen coating method, a spray coating method, an impregnation method, a spray method, or the like. Further, a peeling layer may be formed on both surfaces of the adhesive layer by arranging another peeling layer on the surface of the adhesive layer formed by applying the adhesive to the peeling layer.

The thickness of the adhesive layer is usually from about 3 to 100 μm, preferably from 5 to 50 μm.

[Manufacture of polarizing plate]

The polarizing plate of the present invention can be produced by laminating a polarizing element, a functional layer, and an adhesive layer to be used in a desired order.

The laminate of the polarizing element layer and the functional layer can be carried out by any suitable method, for example, an interlayer can be used to bond the layers. A water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive can be used as the adhesive, and a water-based adhesive or an active energy ray-curable adhesive is preferably used from the viewpoint of productivity. About the connection in the obtained polarizing plate The thickness of the coating layer may be about 0.01 to 0.2 μm in the case of, for example, a water-based adhesive, and may be 0.1 to 4 μm in the case of an active energy ray-curable adhesive.

The water-based adhesive is one in which the adhesive component is dissolved in water or dispersed in water. A water-based adhesive suitable for use is, for example, an adhesive composition using a polyvinyl alcohol-based resin or a urethane resin as a main component.

When a polyvinyl alcohol-based resin is used as a main component of the adhesive, the polyvinyl alcohol-based resin may be, for example, a carboxy-modified polycondensation such as a partially saponified polyvinyl alcohol or a fully saponified polyvinyl alcohol. A modified polyvinyl alcohol-based resin such as vinyl alcohol, ethylene glycol modified polyvinyl alcohol, hydroxymethyl modified polyvinyl alcohol or amine modified polyvinyl alcohol. The polyvinyl alcohol-based resin may be a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of ethyl acetate, or may be ethyl acetate and other copolymerizable with the ethyl acetate. The polyvinyl alcohol-based copolymer obtained by saponifying the copolymer of the monomer.

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

In order to improve the adhesion, the adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin preferably contains a polyvalent aldehyde, a melamine-based compound, a zirconia compound, a zinc compound, glyoxal, a glyoxal derivative, and a water-soluble ring. A curable component such as an oxygen resin or a crosslinking agent. As the water-soluble epoxy resin, for example, diethylidene monoamine, diethylidenetetramine, etc. can be suitably used. A polyamidoamine epoxy resin obtained by reacting a polyamine amine obtained by reacting a dicarboxylic acid such as an alkyl polyamine and adipic acid with epichlorohydrin. Commercial products of the polyamine polyamine epoxy resin include "Sumirez Resin 650" (manufactured by Tajika Chemical Industry Co., Ltd.), "Sumirez Resin 675" (made by Tiangang Chemical Industry Co., Ltd.), and "WS-525". (Japan PMC (share) system) and so on. 100 parts by weight of the polyvinyl alcohol-based resin, and the addition amount of the curable component or the crosslinking agent (the total amount thereof when the curable component and the crosslinking agent are simultaneously added) is usually 1 to 100 parts by weight, preferably 1 Up to 50 parts by weight. When the amount of the curable component or the crosslinking agent added is less than 1 part by weight based on 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving the adhesion tends to be small, and the polyvinyl alcohol-based resin is preferred. When the amount of the resin is more than 100 parts by weight based on 100 parts by weight of the resin, the adhesive layer tends to be brittle.

Moreover, a suitable example of the case where a urethane resin is used as a main component of the adhesive agent is a mixture of a polyester-based ionic polymer-type urethane resin and a compound having a glycidoxy group. The polyester-based ionic polymer type urethane resin refers to a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced therein. Since the ionic polymer type urethane resin is directly emulsified in water without using an emulsifier to form an emulsion, it is suitable as an aqueous binder.

The active energy ray-curable adhesive is an adhesive which is hardened by irradiation of an active energy ray such as ultraviolet rays, visible light, electron beams, or 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.

Active energy ray-curable adhesive The epoxy-based compound which is oxidized by ion polymerization is preferably an ultraviolet curable adhesive containing the epoxy-based compound as a curable component as an adhesive for the curable component. The epoxy compound referred to herein means a compound having an average of one or more, 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-based compound which can be suitably used include a hydrogenated epoxy compound obtained by reacting an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol with epichlorohydrin (having An aliphatic epoxy compound such as a polyglycidyl ether of an aliphatic alicyclic or an alkylene oxide adduct thereof; one or more alicyclic groups in the molecule; An alicyclic epoxy compound of a ring-bonded epoxy group epoxy compound.

The active energy ray-curable adhesive may contain a radically polymerizable (meth)acrylic compound as a curable component instead of the epoxy compound or both an epoxy compound and a (meth)acrylic compound. Examples of the (meth)acrylic compound include a (meth) acrylate monomer having at least one (meth) propylene fluorenyloxy group in the molecule, and a compound obtained by reacting two or more kinds of functional groups. Further, a compound containing a (meth) acryloxy group such as a (meth) acrylate oligomer having at least two (meth) acryloxy groups in the molecule.

When the active energy ray-curable adhesive contains an epoxy compound which is cured by cationic polymerization as a curable component, it is preferred to contain a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic sulfonium salts, and aromatic sulfonium salts. Strontium salt; iron-arene complex and the like. Further, when the active energy ray-curable adhesive contains a radically polymerizable curable component such as a (meth)acrylic compound, it is preferred to contain a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include an acetophenone-based initiator, a diphenylketone-based initiator, a benzoin ether-based initiator, a thioxanthone-based initiator, and an oxa compound. Anthrone, anthrone, camphorquinone, benzaldehyde, anthraquinone, etc.

Before the protective film is bonded to the polarizing film, surface activation treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment may be performed on the bonding surface of the polarizing film and/or the protective film. By the surface activation treatment, the adhesion between the polarizing film and the protective film can be improved.

When the adhesive layer is used, the polarizing element layer or the functional layer can be laminated by its own adhesiveness. More specifically, when a release layer is present on the layer of the adhesive layer, the release layer can be laminated by peeling off the adhesive layer and transferring the adhesive layer to the polarizing element layer or the functional layer.

[Manufacture of Image Display Device]

The polarizing plate manufactured in the above manner is bonded to another member (optical member) through an adhesive layer to obtain an image display device. More specifically, when a peeling layer is present on the bonding surface of the adhesive layer, the peeling layer can be peeled off and the polarizing plate can be bonded to another member by the adhesiveness of the 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 electric field light-emitting display device can be obtained by bonding to an organic electric field light-emitting device. The liquid crystal cell or the organic electroluminescent element to be bonded to the polarizing plate may be any known one. Liquid crystal cell or organic electric field light-emitting element Among them, the constituent elements directly bonded to the polarizing plate are typically glass plates.

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

(Example)

<Example 1>

(A) Production of polarizing elements

A long polyvinyl alcohol film (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more, thickness: 60 μm) was continuously conveyed and immersed in a swelling bath composed of pure water at 20 ° C. And stay for 31 seconds (swelling step). Thereafter, the film drawn from the swelling bath was immersed in a 30 ° C dye bath containing 2/100 (by weight) of potassium iodide/water and held for 122 seconds (dyeing step). Next, the film drawn from the dyeing bath was immersed in a crosslinking bath of potassium iodide/boric acid/water of 12/4.1/100 (weight ratio) at 56 ° C for 70 seconds, followed by immersion in potassium iodide / boric acid / water of 9 /2.9/100 (by weight) in a 40 ° C cross-linking bath and stayed for 13 seconds (crosslinking step). In the dyeing step and the crosslinking step, longitudinal one-axis stretching is carried out by stretching between rolls in a water bath. The total stretch ratio based on the embryonic membrane was set to 5.5 times. Next, the film pulled out from the crosslinking bath was immersed in a washing bath composed of pure water at 5 ° C for 3 seconds (washing step), introduced into a drying oven at 80 ° C and left for 190 seconds. Drying (drying step) gives a polarizing element. The thickness of the polarizing element obtained in this example was 23.6 μm.

(B) Production of polarizing plate

The polarizing element obtained in the above (A) is continuously conveyed while the long first functional layer (first protective film) [Konica Minolta Opto Co., Ltd. TAC film "KC8UX", thickness: 80 μm] and a long second functional layer (second protective film) [TAC film "KC8UX" manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 μm] were continuously conveyed. When a water-based adhesive is injected between the polarizing element and the first functional layer and between the polarizing element and the second functional layer, the first functional layer/water-based adhesive layer/polarizing element/water system is obtained by bonding between the rolls. A laminate film composed of the second layer and the second functional layer. Next, the obtained laminated film was conveyed and introduced into a drying oven at 60° C., and left to stand for 100 seconds for heat treatment, whereby the aqueous adhesive layer was dried to obtain a polarizing plate. In the above-mentioned water-based adhesive, an aqueous solution obtained by dissolving a polyvinyl alcohol powder (trade name "Gohsefimer" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100) in hot water at 95 ° C is used. In a 3% by weight aqueous solution of polyvinyl alcohol, a crosslinking agent (sodium glyoxylate manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a ratio of 1 part by weight based on 10 parts by weight of the polyvinyl alcohol powder is mixed. .

(C) Fabrication of a polarizing plate with an adhesive layer

A commercial product of a commercially available acrylic pressure-sensitive adhesive sheet formed on a release layer (release film) having a thickness of 25 μm was used, and an adhesive having a thickness of 25 μm was formed on the second functional layer of the polarizing plate obtained in the above (B). Layer, a polarizing plate with an adhesive layer is prepared.

(D) Elastic modulus of the polarizing element of the polarizing element in the axial direction (tensile elastic modulus)

From the polarizing element obtained in the above (A), a rectangular test piece in which the length of the polarizing element in the axial direction of the polarizing element was 100 mm and the width in the absorption axis direction of the polarizing element was 20 mm was cut. Then, the longitudinal direction of the test piece (the direction in which the polarizing element penetrates the axis) is set so that the interval between the jigs is 5 cm by the upper and lower jigs of the tensile testing machine (the universal testing machine AG-1S testing machine manufactured by Shimadzu Corporation) The two ends are clamped, and the test piece is stretched in the longitudinal direction (the direction in which the polarizing element penetrates the axis) at a tensile speed of 5 mm/min in an environment of 23 ° C, from the initial straight line in the obtained stress-strain curve. The slope was calculated from the elastic modulus (tensile elastic modulus) [MPa] of the polarizing element in the direction of the axial direction of the polarizing element at 23 °C. The elastic modulus E _P of the polarizing element in the polarization direction of the polarizing element of the present embodiment calculated as described above was 4773 MPa.

(E) Boron content of polarizing element

About 0.2 g of the polarizing element was added to 170 ml of pure water, and after completely dissolving at 95 ° C, 30 g of an aqueous mannitol solution (12.5 wt%) was added as a sample solution for measurement. Before the sample solution for measurement reached the neutralization point, an aqueous sodium hydroxide solution (1 mol/l) was dropped, and the amount of dropwise addition was calculated from the following formula to calculate the boron content (% by weight) in the polyvinyl alcohol film. The polarizing element of the present embodiment thus calculated had a boron content of 3.8% by weight.

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

(F) Elastic modulus of the polarizing element of the functional layer in the axial direction (tensile elastic modulus)

The length of the first functional layer and the second functional layer used in the production of the polarizing plate of the above (B) is 100 mm in the direction parallel to the direction in which the polarizing element penetrates the axis, and the polarizing element A test piece having a rectangular shape with a width of 20 mm in the direction in which the absorption axis directions are parallel. Then, the longitudinal direction of the test piece (with the direction of the polarization axis of the polarizing element) was measured by using the upper and lower jigs of a tensile testing machine (the universal testing machine AG-1S testing machine manufactured by Shimadzu Corporation) to make the interval of the jigs 5 cm. Both ends of the parallel direction are clamped, and the test piece is stretched in the longitudinal direction (direction parallel to the direction in which the polarizing element penetrates the axis) at a tensile speed of 5 mm/min in an environment of 23 ° C, and the resulting stress is obtained. - The slope of the initial straight line in the strain curve calculates the elastic modulus (tensile elastic modulus) [MPa] of the direction of the transmission axis of the polarizing element of the functional layer at 23 °C. The elastic modulus E _F1 of the polarizing element in the first functional layer of the present embodiment and the elastic modulus E _{F2 in the} direction of the transmission axis of the polarizing element of the second functional layer were 4,169 MPa.

(G) Elastic modulus of the polarizing element of the adhesive layer in the axial direction (tensile elastic modulus)

Only the adhesive layer is cut out from the adhesive sheet used in the production of the polarizing plate of the pressure reducing layer of the above (C), and is a length in the direction parallel to the direction in which the polarizing element penetrates the axis in the obtained polarizing plate. A rectangular test piece having a width of 5 mm and a direction parallel to the absorption axis direction of the polarizing element was 50 mm. Then, the longitudinal direction of the test piece (with the direction of the polarization axis of the polarizing element) was obtained by using the upper and lower jigs of the precision universal testing machine (the universal testing machine AGS-50NX testing machine manufactured by Shimadzu Corporation) to make the interval of the jigs 3 cm. The two ends of the parallel direction are clamped, and the test piece is stretched in the longitudinal direction (direction parallel to the direction in which the polarizing element penetrates the axis) at a tensile speed of 300 mm/min in an environment of 23 ° C, and the resulting stress is obtained. - The slope of the initial straight line in the strain curve was calculated from the elastic modulus (tensile elastic modulus) [kPa] of the direction of the transmission axis of the polarizing element of the adhesive layer at 23 °C. The elastic modulus E _PSA of the polarizing element in the direction of the axial direction of the adhesive layer of the present embodiment calculated as described above was 135 kPa.

(H) Difference in modulus of elasticity

The elastic modulus difference ΔE is calculated by subtracting the following E _F from the elastic modulus E _P of the polarizing element in the direction perpendicular to the axis of the polarizing element obtained in the above (D): the first functional layer obtained by the above (F) When the elastic modulus E _F1 of the polarizing element penetrates the axial direction and the elastic modulus E _F2 of the polarizing element of the second functional layer in the direction of the transmission axis are the same, the value is taken as E _F , and the larger one is taken when the difference is different. The value is taken as E _F . The elastic modulus difference ΔE of the present embodiment calculated therefrom was 604 MPa.

(I) Evaluation of crack resistance

From the polarizing plate with the adhesive layer obtained in the above (C), a rectangular test piece in which the length of the polarizing element in the axial direction of the polarizing element was 80 mm and the width in the absorption axis direction of the polarizing element was 60 mm was cut. The test piece was attached to a glass plate and placed in an oven at 80 ° C for 1 hour. The test piece attached to the glass plate was taken out from the oven, and kept at 23 ° C and a relative humidity of 55% for 15 minutes, and then immersed in water at 23 ° C for 30 minutes. After the test piece attached to the glass plate was taken out from the water, the moisture of the test piece was removed by air jet. Thereafter, the end portion of the longitudinal direction of the test piece (the direction in which the polarizing element penetrates the axis direction) was visually observed using a magnifying glass (magnification: 10 times), and the number of cracks was counted. No cracks were confirmed in this example.

<Examples 2 to 4>

The first functional layer and the second functional layer when the polarizing plate was produced were changed to the same as in the first embodiment, and the same manner as in the first embodiment. A polarizing plate and a polarizing plate with an adhesive layer. Here, the details of the abbreviations of the functional layers in Table 1 are as follows.

[a] TAC1: TAC film "KC8UX2MW" manufactured by Konica Minolta Opto Co., Ltd. has a thickness of 80 μm

[b]TAC2: TAC film "KC4UYW" made by Konica Minolta Opto Co., Ltd. has a thickness of 40 μm

[c] TAC3: TAC film "KC2UAW" manufactured by Konica Minolta Opto Co., Ltd. has a thickness of 25 μm

[d] COP1: The product name "Arton film FEKB015D3" of the cyclic polyolefin resin film manufactured by JSR Co., Ltd. has a thickness of 15 μm.

[e] COP2: The product name "Zeonor film ZF14-023" of the cyclic polyolefin resin film manufactured by Japan ZEON Co., Ltd. has a thickness of 23 μm.

[f] COP3: The product name "Zeonor film ZT12-090079" of the cyclic polyolefin resin film manufactured by Japan ZEON Co., Ltd. has a thickness of 21 μm, an in-plane phase difference of 90 nm, and a thickness phase difference of 79 nm.

<Example 5, Comparative Examples 1 to 3>

In addition to the manufacture of the polarizing element, it was immersed in a cross-linking bath of potassium iodide/boric acid/water of 12/1.5/100 (by weight) at 56 ° C for 70 seconds, followed by immersion in potassium iodide / boric acid / water of 9 / In a cross-linking bath of 40° C. at a ratio of 1.5/100 (weight ratio) for 13 seconds (crosslinking step), the first functional layer and the second functional layer in the production of the polarizing plate were changed to those shown in Table 1. Further, a polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 1.

<Example 6>

In addition to the preparation of the polarizing element, it is immersed in potassium iodide / boric acid / water It is 12/5.0/100 (weight ratio) in a crosslinking bath of 56 ° C and stays for 70 seconds, and then immersed in a crosslinking bath of 40 ° C of potassium iodide / boric acid / water of 9 / 5.0 / 100 (weight ratio) and The polarizing plate and the adhesive were produced in the same manner as in Example 1 except that the first functional layer and the second functional layer when the polarizing plate was produced were changed to those shown in Table 1. a polarizing plate of the agent layer.

<Example 7>

In addition to the use of a long-length polyvinyl alcohol film (average degree of polymerization: about 2,400, degree of saponification: 99.9 mol% or more, thickness: 30 μm), the first functional layer and the second functional layer when the polarizing plate was produced were changed to A polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 1 except as shown in Table 1.

<Example 8>

A polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 7 except that the total stretching ratio based on the embryonic film was 5.4 times when the polarizing element was produced.

<Example 9>

In addition to the preparation of the polarizing element, it was immersed in a cross-linking bath of potassium iodide/boric acid/water of 12/1.5/100 (by weight) at 56 ° C for 70 seconds, followed by immersion in potassium iodide / boric acid / water of 9 / In a cross-linking bath of 40° C. at a ratio of 1.5/100 (weight ratio) for 13 seconds (crosslinking step), the first functional layer and the second functional layer in the production of the polarizing plate were changed to those shown in Table 1. Further, a polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 7.

<Comparative Example 4>

In addition to the change of the first functional layer and the second functional layer when the polarizing plate is manufactured A polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 9 except that the results are shown in Table 1.

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

With reference to Table 1, it is confirmed that in Examples 1 to 9 in which the elastic modulus difference ΔE is -1100 MPa or more, the number of cracks is 20 or less, whereas the difference in elastic modulus ΔE is -1200 MPa or less. In Comparative Examples 1 to 4, the number of cracks was 80 or more, which was remarkably lowered.

<Examples 10 to 13>

The same procedure as in Example 1 or 6 was carried out, except that a commercially available acrylic pressure-sensitive adhesive sheet different from that of the user of Example 1 was used, and an adhesive layer having a thickness of 25 μm was formed on the second functional layer of the polarizing plate. A polarizing plate with an adhesive layer is produced in a manner. The elastic modulus E _PSA of the polarizing element of each adhesive layer in the axial direction is shown in Table 2.

The conditions and results of the respective examples are shown in Table 2.

(industrial availability)

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

1‧‧‧Polarized elements

3, 5‧‧‧ functional layer

10‧‧‧Polar plate

Claims (9)

A polarizing plate comprising a polarizing element and a functional layer laminated on at least one side of the polarizing element, wherein the elastic modulus of the polarizing element from the polarizing element penetrates the axial direction minus the elasticity of the polarizing element of the functional layer in the axial direction The value after the modulus is -1100 MPa or more and 1668 MPa or less. The polarizing plate of claim 1, wherein the functional layer comprises a protective film. The polarizing plate of claim 1 or 2, wherein the functional layer comprises a retardation film. The polarizing plate according to claim 1 or 2, wherein the polarizing element has a functional layer on one area of the polarizing element and the other layer of the polarizing element has an adhesive layer. The polarizing plate according to claim 1 or 2, wherein the surface layer of one side of the polarizing plate has an adhesive layer or an adhesive layer with a release layer. The polarizing plate according to claim 4, wherein the polarizing element of the adhesive layer has an elastic modulus in the axial direction of 50 kPa or more and 1000 kPa or less. The polarizing plate according to claim 5, wherein the polarizing element of the adhesive layer has an elastic modulus in the axial direction of 50 kPa or more and 1000 kPa or less. The polarizing plate according to claim 1 or 2, wherein the elastic modulus of the polarizing element from the polarizing element penetrates the axial direction minus the elastic modulus of the polarizing element of the functional layer in the axial direction Value 1500MPa or less. An image display device comprising a liquid crystal cell or an organic electroluminescent device, and a polarizing plate according to any one of claims 1 to 8.