TW201809761A - Polarizing plate and image display device - Google Patents

Abstract

An objective of this invention is to provide a polarizing plate with improved crack rasistance in an environment in contact with water. The polarizing plate of this invention contains a polarizer and a functional layer laminated on at least one side of the polarizer, wherein, the value obtained by suberacting the elastic module of the functional layer in the transmission axis direction of the polarizer from the elastic module of the polarizer in the transmission axis direction of the polarizer is -1100MPa or more.

Description

Polarizing plate and image display device

The present invention relates to a polarizing plate that can be used in various optical applications. The present invention relates to an image display device having the polarizing plate.

The polarizing plate is widely used as a polarizing light supplying element and a polarizing light detecting element in an image display device. In such a polarizing plate, for example, a polarizing element obtained by subjecting a polyvinyl alcohol-based resin film to stretching, dyeing, or crosslinking is suitably used. When a crack occurs in a polarizing element, an appearance defect and an optical defect called "light leakage" may occur. Conventionally, in order to prevent cracks in a polarizing element, various proposals have been made (see Patent Documents 1 to 5).

[Prior technical literature] [Patent Literature]

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

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

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

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

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

The occurrence of cracks in polarizing elements can be caused by various reasons. The representative is that fissures will be generated due to the intense temperature change (heat shock) of the surrounding environment exposed when the product is used. At this time, the test is accelerated by heat shock, for example, at -40 ° C. The test of thermal cycling between 85 ° C and 20 cycles (Patent Document 2) or the test of thermal cycling between -35 ° C and 85 ° C (Patent Document 4) can evaluate the occurrence of cracks. Degree. In the manufacturing process of a product, when a protective film is transferred to a polarizing laminated film including a base film, a laminated layer, and a polarizing element layer formed thereon (Patent Document 3), Cracks are generated by the force (physical / mechanical punching) applied during the cutting process of the polarizer of the polarizer (Patent Document 4). At this time, the degree of crack generation can be confirmed after such operations.

In contrast, the inventors of this case are concerned about the occurrence of cracks due to condensation that may occur when the product is used. Since condensation causes contact with water, it is believed that it is caused by cracks due to a mechanism different from that generated by thermal shock or physical / mechanical shock as described above.

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

As a result of research by the inventors of the present case, a polarizing plate including a polarizing element and a functional layer laminated on at least one side of the polarizing element will be bonded to glass. The plate-made sample was subjected to a crack promotion test (including immersion in water) modeled after condensation, and it was clear that cracks would extend from the end face of the polarizing element along the penetrating axis direction to the slightly absorbing axis direction. In addition, the inventors of this case have obtained the unique knowledge and insight that the functional layer laminated on at least one side of the polarizing element, the smaller the elastic modulus of the polarizing element in the direction of the penetrating axis, the more difficult it is in an environment in contact with water A crack is generated, and the greater the difference between the elastic modulus of the polarizing element in the direction of the transmission axis and the elastic modulus of the polarizing element in 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. As a result of further research, the present invention has been completed.

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 side of the polarizing element, wherein the polarizing element penetrating axis of the functional layer is subtracted from the elastic modulus of the polarizing element in the polarization axis direction of the polarizing element. The value after the elastic modulus in the direction is -1100 MPa or more.

[2] The polarizing plate according to [1], wherein the functional layer includes a protective film.

[3] The polarizing plate according to [1] or [2], wherein the functional layer includes a retardation film.

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

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

[6] The polarizing plate according to [4] or [5], wherein the elastic modulus of the polarizing element of the adhesive layer in the transmission axis direction is 1000 kPa or less.

[7] An image display device including a liquid crystal cell or an organic electric field light emitting element, 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 having improved crack resistance in an environment in contact with water. Furthermore, 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 against condensation.

1‧‧‧ polarizing element

3, 5‧‧‧ functional layer

7‧‧‧ Adhesive layer

10, 11, 12‧‧‧ polarizing plates

15‧‧‧ Other components (such as liquid crystal cell, organic electric field light-emitting element, etc.)

20‧‧‧Image display device

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

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

Fig. 3 is a schematic 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 are described in detail, but the present invention is not limited to these embodiments.

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

The "polarizing element" 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 direction of the polarization axis of the polarizing element can be understood as the vibration direction 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. In addition, in general, the polarizing element may be an extended film, the absorption axis direction of the polarizing element may be consistent with its extending direction (MD), and the polarization axis direction of the polarizing element may be consistent with the width direction (TD).

In the present invention, the "functional layer" means a layer provided for the purpose of exerting or imparting a certain function to the polarizing element, such as a physical, mechanical, and / or optical function. The functional layer is formed by laminating a polarizing element by any appropriate method. For example, the functional layer can be bonded to the polarizing element using an adhesive.

The functional layer includes, for example, a protective film, a retardation film, a brightness enhancement film, and the like, which may be any of these single layers or a laminate of any two or more of them. The protective film may be any one that can perform the function of protecting the polarizing element. The protective film may have no optical function or have both optical functions. Parallax film or brightness enhancement film. In addition, a layer such as a hard coat layer, an anti-reflection layer, and an anti-glare layer may be formed on the surface of the protective film opposite to the side where the polarizing element is attached. Although the present inventors are not limited, the functional layer may be a separate protective film, or a laminated product of a protective film and a retardation film.

The polarizing plate of the present invention is a value that satisfies the elastic modulus of the polarizing element in the transmission axis direction of the polarizing element minus the elastic modulus of the polarizing element in the functional layer in the transmission axis direction (ΔE, hereinafter simply referred to as "the elastic modulus "Poor") 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 polarizer in the direction of the transmission axis of the polarizer (MPa)

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

The term “polarizing element transmission axis direction” in the present invention means a direction that is parallel to or slightly parallel to the direction of the polarization axis of the polarizing element (the included angle is within ± 7 degrees).

By setting the above-mentioned elastic modulus difference ΔE to be -1100 MPa or more, it is possible to provide a polarizing plate having improved crack resistance and excellent durability in an environment in contact with water. The polarizing plate of the present invention does not generate light leakage (light leakage when observed under orthogonal polarization by a polarizing microscope), cracks, etc. even in an environment where condensation occurs, and can display good polarization characteristics. The difference in elastic modulus ΔE is more preferably about -1000 MPa or more, and the upper limit is not particularly limited. For example, it may be about 3000 MPa or less, especially about 2500 MPa or less, preferably 2,000 MPa or less, and more preferably 1500 MPa or less. .

Although the elastic modulus EP of the polarizing element in the direction of the transmission axis of the polarizing element varies depending on the material and manufacturing method of the polarizing element, it may be, for example, about 3500 to 6000 MPa, preferably 5500 MPa or less, and more preferably 5000 MPa or less. In order to increase the difference in elastic modulus ΔE = E _P -E _F , the larger the elastic modulus E _P of the polarization axis of the polarizing element in the transmission axis direction is, the better. On the other hand, cracks occur from the viewpoint of suppression of molding a polarizing plate, the polarizing element of the polarizer transmission axis direction of the elastic modulus E _P is the less preferred. When the elastic modulus E _P of the polarizing element in the polarization axis direction of the polarizing element is in the above-mentioned range, it is easy to achieve both. Although the present invention is not limited, when, for example, a polarizing element obtained by subjecting a polyvinyl alcohol-based resin film to stretching, dyeing, or crosslinking in a boric acid solution, the boron in the polarizing element is increased by increasing the stretching ratio. The content rate and / or introduction of a cross-linking agent other than boric acid such as glyoxal and glutaraldehyde can further increase the elastic modulus of the polarizer in the direction of the penetrating axis of the polarizer.

The elastic modulus of the polarizing element in the polarization axis direction of the polarizing element is measured as the tensile elastic modulus (MPa) of the polarizing element in the axis direction of the polarizing element at a predetermined temperature (typically 23 ° C). More specifically, a test piece is cut out from the polarizing element, and both ends of the polarizing element penetrating axis direction of the test piece are clamped by a testing machine under a predetermined temperature environment, and stretched along the polarizing element penetrating axis direction. From this, 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 in the transmission axis direction varies depending on the composition of the functional layer, the presence or absence of the optical characteristics, or the degree, etc., but in order to respond to the elastic modulus EP of the polarizing element in the transmission axis direction of the polarizing element, The formula (1) is satisfied, and can be appropriately selected, for example, from a range of about 1,000 to 10,000 MPa. In order to increase the difference in elastic modulus ΔE = E _P -E _F , the smaller the elastic modulus E _F of the polarizing element of the functional layer in the transmission axis direction is, the better. Although the present invention is not limited, when the functional layer has alignment, the functional layer can be reduced by reducing the degree of alignment and / or using a material composed of a rigid structure such as a main chain that does not have a ring structure to reduce the functional layer. The modulus of elasticity of the polarizing element through the axis. In addition, the "polarizing element transmission axis direction" of the functional layer means that when the functional layer is laminated on the polarizing element, it means that it is parallel or slightly parallel to the polarization axis direction of the polarizing element (the angle included is within ± 7 degrees) ).

The elastic modulus of the polarizing element of the functional layer in the transmission axis direction is measured as the tensile elastic modulus (MPa) of the polarizing element of the functional layer in the transmission axis direction at a predetermined temperature (typically 23 ° C.). In more detail, a test piece is cut out from the functional layer, and both ends of the polarizing element transmission axis direction of the test piece are clamped by a testing machine under a predetermined temperature environment, and stretched along the polarizing element transmission axis direction, From this, the elastic modulus can be calculated from the slope of the initial straight line in the obtained stress-strain curve.

As shown in FIG. 1 and FIG. 2, when the first functional layer 3 and the second functional layer 5 are laminated on both sides of the polarizing element 1, respectively, the polarizing plate of the present invention satisfies the polarization axis direction of the polarizing element of the polarizing element. The value of the elastic modulus of the polarizing element of the first functional layer after subtracting the elastic modulus of the polarization axis of the first functional layer is -1100 MPa or more, and the elastic modulus of the polarizing element of the polarizing element is subtracted from the elastic modulus of the second functional layer. The value after the elastic modulus of the polarizing element in the transmission axis direction is -1100 MPa or more. At this time, when E _F in the above formula (1), the elastic modulus in the transmission axis direction of the polarizing element of the first functional layer is the same as the elastic modulus in the transmission axis direction of the polarizing element of the second functional layer. This value is represented by the value of the larger one at the same time.

As shown in FIG. 2 and FIG. 3, the adhesive layer 7 that can be included in the polarizing plate of the present invention (after the peeling layer is peeled off when a peeling layer is present on the surface) is used to make the polarizing plates 11, 12 and Other components fit.

The elastic modulus of the polarizing element of the adhesive layer in the penetrating axis direction may be 5000 kPa or less, preferably 1000 kPa or less. When the polarizing plate is adhered to the liquid crystal display device or the like through the adhesive layer, it can be contacted with water. The crack resistance in the environment is effectively improved. The elastic modulus of the polarizing element of the adhesive layer in the transmission axis direction is more preferably about 500 kPa or less, and even more preferably 150 kPa or less. The lower limit of the elastic modulus of the polarizing element of the adhesive layer in the transmission axis direction is not particularly limited, and may be, for example, about 50 kPa or more. Although the present invention is not limited, for example, by mixing an oligomer such as a polyurethane acrylate oligomer with a known adhesive, and / or adding a crosslinking agent such as an isocyanate crosslinking agent, the adhesive layer can be The elastic modulus of the polarizing element in the transmission axis direction is adjusted to the above range. When the elastic modulus of the polarizer of the adhesive layer in the penetrating axis direction is within the above range, it is easy to simultaneously suppress the dimensional change of the polarizing plate and relax the stress. In addition, when the “polarizing element penetration axis direction” of the adhesive layer is laminated on the polarizing element, it means that it is parallel or slightly parallel to the polarization axis direction of the polarizing element (the included angle is ± 7 Within degrees).

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

As shown in FIG. 4, for example, the polarizing plate 11 can be bonded to another member 15 through the adhesive layer 7 to form an image display device 20. The other members are not particularly limited, and may be, for example, a liquid crystal cell, an organic electric field light emitting device, or the like. As a representative, a polarizing plate may be bonded to the glass plate constituting the above 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 element. However, the image display device of the present invention is not limited to this embodiment, and may have any appropriate structure as long as it includes a liquid crystal cell or an organic electric field light emitting element 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 according to the occasion are prepared.

[Polarizer]

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

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. In addition to polyvinyl acetate, which is a homopolymer of ethyl acetate, polyvinyl acetate resins can also be copolymers of ethyl acetate and other monomers copolymerizable with the ethyl acetate. As with ethyl acetate Examples of other monomers for ester copolymerization include unsaturated carboxylic acid, olefin, vinyl ether, unsaturated sulfonic acid, and acrylamide having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin may be in a range of 80 mol% or more, but 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 those modified by the following: an olefin such as ethylene and propylene; acrylic acid, methacrylate, and 2-butene Unsaturated carboxylic acids such as acids; alkyl esters of unsaturated carboxylic acids and acrylamide. The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and still more preferably 2,000 to 5,000.

The polarizing element can be crosslinked (crosslinked) by, for example, uniaxially extending an embryonic membrane made of a polyvinyl alcohol-based resin, swelling with water (swelling step), dyeing with a dichroic dye (staining step), or an aqueous boric acid solution Step), washing with water (washing step), and finally drying (drying step).

One-axis extension of the polyvinyl alcohol-based resin film may be either dry extension in the air, wet extension in the water bath, or both. In order to increase the elastic modulus E _P of the polarizing element in the direction of the penetrating axis of the polarizing element, it is better to carry out the stretching with a wet extension which is beneficial to increase the extension ratio. The wet-stretching system can be stretched, for example, in a state where the polyvinyl alcohol-based resin film is immersed in the processing bath between and / or before and after the dyeing step and / or the crosslinking step. When uniaxial stretching is performed, the polyvinyl alcohol-based resin film may be stretched between rolls having different peripheral rotation speeds, or the polyvinyl alcohol-based resin film may be stretched by 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, water is used to swell the polyvinyl alcohol-based resin film. The swelling treatment can be performed by immersing a polyvinyl alcohol-based 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.

The dyeing step is to dye a polyvinyl alcohol-based resin film with a dichroic dye, and make the film adsorb the dichroic dye. The dyeing process may be, for example, immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically, iodine or a dichroic dye can be used.

When iodine is used as a dichroic dye, a polyvinyl alcohol-based resin film is usually dipped in an aqueous solution containing iodine and potassium iodide to dye it. The content of iodine in the aqueous solution may generally 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 may generally be 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 dyeing is generally adopted. The content of the dichroic dye in the aqueous solution usually accounts for about 1 × 10 ^-3 to 1 part by weight per 100 parts by weight of water. The aqueous solution may contain inorganic salts 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.

The crosslinking step is, for example, dyeing a polyvinyl alcohol-based tree. The lipid film is immersed in an aqueous boric acid solution. The content of boric acid in the boric acid aqueous solution 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, the boric acid aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous 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 in the boric acid aqueous solution is usually about 10 to 600 seconds, preferably 20 seconds or more, and preferably 300 seconds or less. The temperature of the boric acid aqueous solution is usually 50 ° C or higher, and preferably 50 to 70 ° C. To the boric acid aqueous solution, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid and the like can be added as a pH adjusting agent. As the boric acid aqueous solution, two or more kinds having different compositions and temperatures can be used. In this case, it is preferable to apply the boric acid concentration of the subsequent boric acid aqueous solution to be lower than the initial boric acid aqueous solution.

The polyvinyl alcohol-based resin film that has undergone the crosslinking step is usually applied to a washing step using water. The washing treatment is performed by immersing a cross-linked polyvinyl alcohol-based 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.

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

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

[Functional layer]

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

The cyclic polyolefin resin is generally a generic name of a resin polymerized by using a cyclic olefin as a polymerization unit, and examples thereof include Japanese Patent Laid-Open No. 1-240517, Japanese Patent Laid-Open No. 3-14882, and Japanese Patent Laid-Open No. 3-122137. Resin described in Japanese Patent Publication No. Specific examples of cyclic polyolefin resins include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymers of chain olefins such as ethylene and propylene and cyclic olefins ( Typical examples are random copolymers), graft polymers modified with unsaturated carboxylic acids or their derivatives, and hydrides such as these. Among them, norbornene-based resins using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers as cyclic olefins are suitably used.

There are various commercially available cyclic polyolefin resins. To Trade names indicate examples of commercially available products of cyclic polyolefin resins: "TOPAS" (registered trademark) produced by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. in Japan, and JSR Co., Ltd. `` Arton '' (registered trademark) sold, `` Zeonor '' (registered trademark) and `` Zeonex '' (registered trademark) sold by Japan Zeon Corporation, and `` Apel '' (registered trademark) sold by Mitsui Chemicals Co., Ltd. )Wait.

As the protective film, a commercially available product of a cyclic polyolefin resin film having been formed can be used. The product names are listed as examples of commercially available products: "Arton film" ("Arton" is a registered trademark of the same company) sold by JSR Co., Ltd., and "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. In addition, those copolymerized or those in which a part of the hydroxyl group is modified with another substituent may be used. Among these, cellulose triacetate (cellulose triacetate: TAC) is particularly preferred. There are many commercially available products of cellulose triacetate, which is also advantageous from the viewpoint of availability or cost. Examples of commercially available products of cellulose triacetate are: "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered trademark)" (Trademark) TD80UZ "and" Fujitac (registered trademark) TD40UZ ", TAC film manufactured by Konica Minolta Co., Ltd. "KC8UX2M", "KC2UA", "KC4UY", etc.

Polyester-based resins are resins other than the above-mentioned cellulose-based resins having an ester bond, and generally include polycondensates of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl naphthalate, and the like. . As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, cocoadiol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

Polycarbonate resins are engineering plastics composed of polymers that bond monomer units through carbonate groups, and are resins with high impact resistance, heat resistance, flame resistance, and transparency. In order to reduce the photoelastic coefficient, the polycarbonate-based resin may be, for example, a resin called a modified polycarbonate with a modified polymer skeleton, or a copolymerized polycarbonate with improved wavelength dependence.

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

Methacrylic acid that can constitute (meth) acrylic resin The ester is preferably an alkyl methacrylate. Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate. Alkyl methacrylates having a carbon number of 1 to 8 such as tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate and the like Based ester. The carbon number of the alkyl group contained in the alkyl methacrylate is preferably from 1 to 4. Among the (meth) acrylic resins, methacrylates may be used alone or in combination of two or more.

Examples of the other polymerizable monomers that can constitute a (meth) acrylic resin include acrylates and other compounds having a polymerizable carbon-carbon double bond in the molecule. 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, third butyl acrylate, and 2-ethylhexyl acrylate. , Alkyl acrylates having 1 to 8 carbon atoms, such as cyclohexyl acrylate, 2-hydroxyethyl acrylate, and the like. The carbon number of the alkyl group contained in the alkyl acrylate is preferably 1 to 4. Among the (meth) acrylic resins, acrylates may be used alone or in combination of two or more.

Other compounds having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene, and styrene, and vinyl cyanide compounds 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 present invention, the functional layer may be Parallax film, brightness enhancement film and other protective films with optical functions. For example, a transparent resin film made of the above-mentioned materials can be stretched (e.g., uniaxially stretched or biaxially stretched), or a liquid crystal layer can be formed on the film, thereby making it possible to provide a retardation film having an arbitrary retardation value. In addition, the functional layer may be a laminate of a protective film and a retardation film.

The functional layer may include a surface treatment layer (coating layer) such as a hard coat layer, an anti-glare layer, an anti-reflection layer, an antistatic layer, and an antifouling layer on a 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 provided on both sides of the polarizing element, the two functional layers may be the same or different from each other. As an example when the functional layers are different, the types of the thermoplastic resin constituting the functional layer are at least different combinations; the presence or absence of the optical function of the functional layers or the types of at least different combinations; The presence or absence of the surface treatment layer or the type thereof is at least a different combination.

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

[Adhesive layer]

As a pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, a conventionally known one may be appropriately selected, and it may be an adhesive having such a degree that peeling does not occur in an environment where the polarizing plate is exposed. Specific examples include propylene From the viewpoints of transparency, weather resistance, heat resistance, and processability, acrylic adhesives are particularly preferred for acid-based adhesives, silicone adhesives, and rubber-based adhesives.

In the adhesive, a thickener, a plasticizer, a glass fiber, a glass bead, a metal powder, a filler composed of other inorganic powder, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, etc. Various additives such as antistatic agents and silane coupling agents.

The adhesive layer is usually formed by applying a solution of an adhesive to a release layer (release film) and drying it. For the coating on the release layer, for example, a roll coating method such as a reverse coating method or a gravure coating method, a notch coating method, a screen coating method, a spray coating method, an impregnation method, or a spray method can be used. In addition, a method in which another release layer is disposed on the surface of the adhesive layer formed by applying the adhesive to the release layer, and a release layer may be formed on both surfaces of the adhesive layer.

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

[Manufacture of polarizing plate]

The polarizing element, the functional layer, and the adhesive layer used depending on the occasion are laminated in the desired order, so that the polarizing plate of the present invention can be manufactured.

The laminated layer of the polarizing element layer and the functional layer may be implemented by any suitable method, for example, the layer may be indirectly bonded using an adhesive. As the adhesive, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used. From the viewpoint of productivity, it is preferable to use a water-based adhesive or an active energy ray-curable adhesive. About the connection in the obtained polarizer The thickness of the adhesive layer may be about 0.01 to 0.2 μm in the case of an aqueous adhesive, and may be 0.1 to 4 μm in the case of an active energy ray-curable adhesive.

Water-based adhesives are those in which the components of the adhesive are dissolved or dispersed in water. A suitable water-based adhesive is, for example, an adhesive composition using a polyvinyl alcohol 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 a polyvinyl alcohol resin such as partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, or may be a carboxyl modified polymer. Modified polyvinyl alcohol-based resins such as vinyl alcohol, acetoacetic acid modified polyvinyl alcohol, methylol modified polyvinyl alcohol, and amino modified polyvinyl alcohol. The polyvinyl alcohol-based resin is not only a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate, which is a homopolymer of ethyl acetate, but also ethyl acetate and other copolymers that can be copolymerized with the ethyl acetate. A polyvinyl alcohol copolymer obtained by saponification of a copolymer of a monomer.

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-based resin in the adhesive is usually 1 to 10 parts by weight, and preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.

In order to improve adhesion, the adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin preferably contains a polyaldehyde, 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, diethylene triamine, diethylene tetramine, and the like can be suitably used. Polyamines obtained by reacting polycarboxylic acids such as polyalkylene polyamines and adipic acid, and polyamine epoxy resins obtained by reacting with epichlorohydrin. Commercially available products of this polyamine polyamine epoxy resin include "Sumirez Resin 650" (manufactured by Taoka Chemical Industry Co., Ltd.), "Sumirez Resin 675" (manufactured by Taoka Chemical Industry Co., Ltd.), and "WS-525" (Japanese PMC (shares) system) and so on. 100 parts by weight of a polyvinyl alcohol-based resin, and the addition amount of the hardening component or the cross-linking agent (the total amount when the hardening component and the cross-linking agent are simultaneously added) is usually 1 to 100 parts by weight, preferably 1 To 50 parts by weight. When the addition amount of the hardening component or the crosslinking agent is less than 1 part by weight relative to 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesion tends to be small. In addition, compared with the polyvinyl alcohol system, When the resin is added in an amount of more than 100 parts by weight, the adhesive layer tends to become brittle.

Moreover, as a suitable example when using a urethane resin as a main component of an adhesive agent, the mixture of a polyester-type ionic polymer type urethane resin and a compound which has a glycidyloxy group is mentioned. 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 into the urethane resin. This ionic polymer urethane resin is suitable for use as an aqueous adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion.

Active energy ray-curable adhesives are adhesives that harden by irradiation with active energy rays such as ultraviolet, visible light, electron beam, and X-rays. When an active energy ray-curable adhesive is used, the adhesive layer included in the polarizing plate is a cured product layer of the adhesive.

Active energy ray hardening adhesive The epoxy-based compound that is cured by ion polymerization as an adhesive for the curable component is preferably an ultraviolet-curable adhesive that contains the epoxy-based compound as the curable component. The epoxy-based 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-based compound may be used alone or in combination of two or more.

Specific examples of the epoxy-based compound that can be suitably used include hydrogenated epoxy-based compounds obtained by reacting an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol with epichlorohydrin (having Glycidyl ether of alicyclic polyhydric alcohols); aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof; having more than one alicyclic type in the molecule An alicyclic epoxy compound of a ring-bonded epoxy epoxy compound.

The active energy ray-curable adhesive may contain a radically polymerizable (meth) acrylic compound as a curable component instead of the epoxy-based compound, or may contain both an epoxy-based compound and a (meth) acrylic-based compound. Examples of the (meth) acrylic compound include a (meth) acrylic acid ester monomer having at least one (meth) acryloxy group in the molecule, and obtained by reacting two or more kinds of compounds containing a functional group, In addition, 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-based compound that hardens by cation polymerization as a curable component, it is preferable to contain a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts; aromatic sulfonium salts and aromatic sulfonium salts. Onium salts; iron-arene complexes, etc. When the active energy ray-curable adhesive contains a radically polymerizable curable component such as a (meth) acrylic compound, it is preferable to contain a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include acetophenone-based initiators, diphenylketone-based initiators, benzoin ether-based initiators, thia anthrone-based initiators, and oxa Anthrone, fluorenone, camphorquinone, benzaldehyde, anthraquinone, etc.

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

When an adhesive layer is used, a polarizing element layer or a functional layer can be laminated using its own adhesiveness. In more detail, when a release layer is present on the build-up layer of the adhesive layer, the release layer can be peeled off and the adhesive layer can be transferred to a polarizing element layer or a functional layer to perform lamination.

[Manufacture of image display device]

The polarizing plate manufactured as described above is bonded to another member (optical member) through an adhesive layer to obtain an image display device. In more detail, when a peeling layer exists on the bonding surface of an adhesive layer, this peeling layer can be peeled and a polarizing plate can be bonded to another member by the adhesiveness of an adhesive layer. For example, a liquid crystal display device can be obtained by attaching a polarizing plate to a liquid crystal cell, and an organic electric field light-emitting display device can be obtained by attaching a polarizing plate to an organic electric field light-emitting element. As long as a known liquid crystal cell or organic electric field light emitting element is bonded to the polarizing plate, it is sufficient. Light-emitting element in liquid crystal cell or organic electric field Among the components that are directly bonded to the polarizing plate, a glass plate is a typical example.

However, it should be noted that the application 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 made of pure water at 20 ° C. Hold for 31 seconds (swelling step). Thereafter, the film pulled out from the swelling bath was immersed in a 30 ° C dyeing bath containing iodine with a potassium iodide / water of 2/100 (weight ratio) and left for 122 seconds (dyeing step). Next, the film drawn from the dyeing bath was immersed in a 56 ° C crosslinking bath with potassium iodide / boric acid / water 12 / 4.1 / 100 (weight ratio) and left for 70 seconds, and then immersed in potassium iodide / boric acid / water 9 /2.9/100 (weight ratio) in a crosslinking bath at 40 ° C for 13 seconds (crosslinking step). In the dyeing step and the cross-linking step, longitudinal uniaxial stretching is performed using roll-to-roll stretching in a water bath. The total elongation ratio based on the embryonic membrane was set to 5.5 times. Next, the film drawn from the cross-linking bath is immersed in a washing bath made of pure water at 5 ° C and left for 3 seconds (washing step), and then introduced into a drying oven at 80 ° C for 190 seconds. Drying (drying step) to obtain a polarizing element. The thickness of the polarizing element obtained in this example is 23.6 μm.

(B) Fabrication of polarizing plate

Continuously transport the polarizing element obtained in the above (A), and simultaneously transfer the long first functional layer (first protective film) [Konica Minolta Opto Co., Ltd. The TAC film “KC8UX” made by the company, thickness: 80 μm] and the long second functional layer (second protective film) [TAC film “KC8UX” made by Konica Minolta Opto Co., Ltd., thickness: 80 μm] are 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-based system is obtained by bonding the rollers. A laminated film composed of an adhesive layer and a second functional layer. Next, the obtained laminated film was conveyed and introduced into a drying furnace at 60 ° C. and left for 100 seconds for heat treatment, thereby drying the water-based adhesive layer to obtain a polarizing plate. The above-mentioned water-based adhesive is an aqueous solution obtained by dissolving polyvinyl alcohol powder [trade name "Gohsefimer" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree: 1100] in hot water at 95 ° C. A cross-linking agent [sodium glyoxylate manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] is added to a polyvinyl alcohol aqueous solution having a concentration of 3% by weight in a ratio of 1 part by weight to 10 parts by weight of the polyvinyl alcohol powder. .

(C) Fabrication of polarizing plate with adhesive layer

Using a commercially available acrylic adhesive sheet formed on the release layer (release film) with a thickness of 25 μm, a 25 μm-thick adhesive was formed on the second functional layer of the polarizing plate obtained in the above (B). Layer to make a polarizing plate with an adhesive layer.

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

A rectangular test piece having a length of 100 mm in the polarization axis direction and a width of 20 mm in the absorption axis direction of the polarizing element was cut out from the polarizing element obtained in the above (A). Next, use the upper and lower clamps of the tensile tester [Universal Tester AG-1S Tester, manufactured by Shimadzu Corporation] to adjust the length of the test piece (polarizing element penetration axis direction) so that the interval between the clamps is 5 cm. The two ends were clamped, and the test piece was stretched in the longitudinal direction (the direction of the polarizing element transmission axis) at a tensile speed of 5 mm / min under an environment of 23 ° C. From the initial straight line in the obtained stress-strain curve, The slope calculated the elastic modulus (tensile elastic modulus) [MPa] of the polarizing element in the direction of the transmission axis of the polarizing element at 23 ° C. The elastic modulus E _P of the polarizing element in the polarization axis direction of the polarizing element of this embodiment calculated based on this is 4,473 MPa.

(E) Boron content of polarizing element

About 0.2 g of a polarizing element was added to 170 ml of pure water, and it was completely dissolved at 95 ° C. Then, 30 g of an mannitol aqueous solution (12.5 wt%) was added as a sample solution for measurement. Before the sample solution for measurement reaches the neutralization point, an aqueous sodium hydroxide solution (1 mol / l) is dropped, and the boron content rate (% by weight) in the polyvinyl alcohol film is calculated from the dropping amount based on the following formula. The boron content of the polarizing element of this example calculated based on this was 3.8% by weight.

Content of boron = 1.08 × dripping amount of sodium hydroxide aqueous solution (ml) / weight of polarizing film (g)

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

From the first functional layer and the second functional layer used when manufacturing the polarizing plate (B), a length in a direction parallel to the polarization axis direction of the polarizing element when the obtained polarizing plate was cut was 100 mm and the polarizing element was cut out. A rectangular test piece having a width of 20 mm in a direction parallel to the absorption axis direction. Next, use the upper and lower clamps of a tensile tester [Universal Tester AG-1S Tester manufactured by Shimadzu Corporation] to adjust the length of the test piece (toward the axis of polarization of the polarizing element) so that the interval between the clamps is 5 cm. The two ends were clamped, and the test piece was stretched in the longitudinal direction (direction parallel to the polarization axis direction of the polarizing element) at a tensile speed of 5 mm / min in an environment of 23 ° C., and the obtained stress was obtained. -The slope of the initial straight line in the strain curve is used to calculate the elastic modulus (tensile elastic modulus) [MPa] of the polarizing element of the functional layer in the transmission axis direction at 23 ° C. Based on this, the elastic modulus E _F1 of the polarizing element in the first axis of the present embodiment in the transmission axis direction and the elastic modulus E _F2 of the polarizing element in the second axis of the transmission axis are 4169 MPa.

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

Only the adhesive layer was cut out of the adhesive sheet used in the production of the polarizing plate of the adhesive reducing layer of (C) above, and was used as a length in a direction parallel to the polarization axis direction of the polarizing element in the obtained polarizing plate. A rectangular test piece having a width of 5 mm and a width of 5 mm in a direction parallel to the absorption axis direction of the polarizing element was 50 mm. Next, use the upper and lower clamps of a precision universal testing machine (universal testing machine AGS-50NX manufactured by Shimadzu Corporation) so that the interval between the clamps is 3 cm so that the length of the test piece (with respect to the direction of the polarization axis of the polarizing element) The two ends were clamped, and the test piece was stretched in the lengthwise direction (direction parallel to the direction of the polarization axis of the polarizing element) at a stretching speed of 300 mm / min in an environment of 23 ° C, and the obtained stress was obtained. -The slope of the initial straight line in the strain curve is used to calculate the elastic modulus (tensile elastic modulus) of the polarizer of the adhesive layer in the direction of the penetration axis at 23 ° C [kPa]. The elastic modulus E _PSA of the polarization axis of the polarizing element of the adhesive layer of this example calculated based on this is 135 kPa.

(H) Elastic modulus difference

The difference in elastic modulus ΔE is calculated by subtracting the following E _F from the elastic modulus E _{P in} the polarization axis direction of the polarizing element of the polarizing element obtained in (D) above: if the first functional layer obtained in (F) above The elastic modulus E _F1 of the polarization axis direction of the polarizing element of the polarizing element and the elastic modulus E _F2 of the polarization axis direction of the polarizing element of the second functional layer are the same when the value is taken as E _F , and the difference is the larger one. as the value of E _F. The elastic modulus difference ΔE of this example calculated based on this was 604 MPa.

(I) Evaluation of crack resistance

A rectangular test piece having a length of 80 mm in the polarization axis direction and a width of 60 mm in the absorption axis direction of the polarizing element was cut out of the polarizing plate with an adhesive layer obtained in (C) above. The test piece was attached to a glass plate and put into an oven at 80 ° C. for 1 hour. After the test piece attached to the glass plate was taken out of the oven, it was kept in an environment 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 of the water, the water in the test piece was removed by air spray. Then, the end of the longitudinal direction (polarizing element transmission axis direction) of the test piece was visually observed using a magnifying glass (magnification 10 times), and the number of cracks was counted. No crack was recognized in this example.

<Examples 2 to 4>

Except that the first functional layer and the second functional layer when the polarizing plate was manufactured were changed to those shown in Table 1, the rest were fabricated in the same manner as in Example 1. 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. with a thickness of 80 μm

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

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

[D] COP1: Trade name "Arton film FEKB015D3" of cyclic polyolefin resin film made by JSR Co., Ltd. Thickness 15 μm

[E] COP2: Trade name "Zeonor film ZF14-023" of cyclic polyolefin resin film made by Japan Zeon Co., Ltd. Thickness 23 μm

[F] COP3: Trade name "Zeonor film ZT12-090079" of a cyclic polyolefin resin film made by Japan Zeon Co., Ltd. The thickness is 21 μm, the in-plane phase difference is 90 nm, and the thickness phase difference is 79 nm.

<Example 5, Comparative Examples 1 to 3>

Except when manufacturing a polarizing element, it was immersed in a 56 ° C crosslinking bath with potassium iodide / boric acid / water 12 / 1.5 / 100 (weight ratio) and left for 70 seconds, and then immersed in potassium iodide / boric acid / water 9 / 1.5 / 100 (weight ratio) in a 40 ° C cross-linking bath for 13 seconds (cross-linking step), and changed the first functional layer and the second functional layer to those shown in Table 1 when manufacturing the polarizing plate In the rest, a polarizing plate and a polarizing plate with an adhesive layer were fabricated in the same manner as in Example 1.

<Example 6>

Except when making polarizing element, it is immersed in potassium iodide / boric acid / water 12 / 5.0 / 100 (weight ratio) in a 56 ° C cross-linking bath for 70 seconds, then immersed in a 40 ° C cross-linking bath with potassium iodide / boric acid / water 9 / 5.0 / 100 (weight ratio) and Leave it for 13 seconds (cross-linking step), and change the first functional layer and the second functional layer when manufacturing the polarizing plate to those shown in Table 1. The rest of the polarizing plate was produced and adhered in the same manner as in Example 1. Polarizer of the agent layer.

<Example 7>

In addition to using a long polyvinyl alcohol film (average degree of polymerization: about 2400, 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 manufactured were changed to Except for those shown in Table 1, a polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 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 extension ratio based on the germ film when manufacturing the polarizing element was 5.4 times.

<Example 9>

Except when manufacturing a polarizing element, it was immersed in a 56 ° C crosslinking bath with potassium iodide / boric acid / water 12 / 1.5 / 100 (weight ratio) and left for 70 seconds, and then immersed in potassium iodide / boric acid / water 9 / 1.5 / 100 (weight ratio) in a 40 ° C cross-linking bath for 13 seconds (cross-linking step), and changed the first functional layer and the second functional layer to those shown in Table 1 when manufacturing the polarizing plate In the rest, a polarizing plate and a polarizing plate with an adhesive layer were fabricated in the same manner as in Example 7.

<Comparative Example 4>

In addition to changing the first functional layer and the second functional layer when manufacturing a polarizing plate Except for those shown in Table 1, a polarizing plate and a polarizing plate with an adhesive layer were produced in the same manner as in Example 9.

The conditions and results of each example and comparative example are summarized and shown in Table 1.

With reference to Table 1, it can be confirmed that in Examples 1 to 9 in which the difference in elastic modulus ΔE is -1100 MPa or more, the number of cracks is 20 or less. In contrast, 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 significantly reduced.

<Examples 10 to 13>

Except that a commercially available acrylic adhesive sheet different from the user in 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, the rest were the same as in Example 1 or 6. Way to make a polarizer with an adhesive layer. Table 2 shows the elastic modulus E _PSA of the polarizing element of each adhesive layer in the transmission axis direction.

The conditions and results of each example are summarized and shown in Table 2.

(Industrial availability)

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

1‧‧‧ polarizing element

3, 5‧‧‧ functional layer

10‧‧‧ polarizing plate

Claims (7)

A polarizing plate includes a polarizing element and a functional layer laminated on at least one side of the polarizing element, wherein the elasticity of the polarizing element in the axial direction of the functional layer is subtracted from the elastic modulus of the polarizing element in the axial direction of the polarizing element. The value after the modulus is -1100 MPa or more. The polarizing plate according to item 1 of the scope of patent application, wherein the functional layer includes a protective film. The polarizing plate as described in claim 1 or claim 2, wherein the functional layer includes a retardation film. According to the polarizing plate described in any one of claims 1 to 3 of the scope of patent application, one area layer of the polarizing element has a functional layer, and the other area layer of the polarizing element has an adhesive layer. According to the polarizing plate described in any one of claims 1 to 4, the surface area layer on one side of the polarizing plate has an adhesive layer or an adhesive layer with a release layer. The polarizing plate according to item 4 or 5 of the scope of patent application, wherein the elastic modulus of the polarizing element of the adhesive layer in the transmission axis direction is 1000 kPa or less. An image display device includes a liquid crystal cell or an organic electric field light-emitting element, and the polarizing plate according to any one of items 1 to 6 of the scope of patent application.