Polarizing plate and image display device using the same

Abstract

To provide a polarizer which is thin even though the polarizer has a low resistance adhesive layer, which is excellent in the durability, suppresses the poor appearance and suppresses a crack in the deformation.SOLUTION: A polarizer according to an embodiment of the present invention comprises: a polarizer; a protective layer which is provided on one side of the polarizer; an iodine transmission suppression layer which is provided on the other side of the polarizer; and an adhesive layer which is provided on the side opposite to the polarizer of the iodine transmission suppression layer. The iodine transmission suppression layer is a solidified object or thermally-cured object of a coating film of an organic solvent solution of a resin. An adhesive composition constituting the adhesive layer includes a base polymer and an anti-static agent. The base polymer has the glass transition temperature equal to or less than -50°C and the dielectric constant at 100 kHz equal to or greater than 5.0. The surface resistance value of the adhesive layer is equal to or less than 1.0×109 Ω / sq.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polarizing plate and an image display device using the same.

Background Art

[0002] Image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. In an image display device, typically, a polarizing plate is bonded to a display panel via an adhesive layer. In recent years, with the development of narrow bezelization of image display devices and so-called in-cell type image display devices in which a conductive layer for a touch panel is incorporated into a display panel, improvement of the antistatic performance of the image display device has been demanded. As a result, improvement of the antistatic performance and reduction of the resistance of the adhesive layer have been demanded. However, in a polarizing plate using such an adhesive layer, there are problems such as deterioration of the durability of the polarizing plate, appearance defects, and generation of cracks when the polarizing plate is processed into a non-rectangular shape other than a rectangle.

Prior Art Documents

Patent Documents

[0006] According to embodiments of the present invention, by configuring a specific structure for the adhesive layer in a polarizing plate having a low-resistance adhesive layer, it is possible to realize a polarizing plate that is thin, highly durable, has suppressed appearance defects (typically partial expansion of the protective layer and cracks in the functional layer contained in the polarizing plate), and has suppressed cracks during shape processing. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0009] A. Overall configuration of polarizing plates Figure 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. The illustrated polarizing plate 100 includes a polarizer 11, a protective layer 12 provided on one side of the polarizer 11, an iodine permeability suppression layer 40 provided on the other side of the polarizer 11, and an adhesive layer 30 provided on the side of the iodine permeability suppression layer 40 opposite to the polarizer 11. The iodine permeability suppression layer 40 is a solidified or thermoset product of a coating film of an organic solvent solution of resin. Another protective layer (not shown) may be provided between the polarizer 11 and the iodine permeability suppression layer 40. Preferably, as in the illustrated example, the protective layer 12 is provided only on one side of the polarizer 11. In this case, the iodine permeability suppression layer 40 is provided directly on the polarizer 11 on the other side of the polarizer 11. In this specification, "provided directly on the polarizer" means that it is formed directly on the polarizer surface without the interposition of an adhesive layer (typically an adhesive layer, a tack layer). The adhesive layer 30 is provided as the outermost layer, and the polarizing plate can be attached to an image display device (essentially, an image display panel). In practical terms, it is preferable that a release film is temporarily attached to the surface of the adhesive layer 30 until the polarizing plate is put into use. By temporarily attaching the release film, the adhesive layer is protected and the polarizing plate can be rolled.

[0010] In embodiments of the present invention, the adhesive composition constituting the adhesive layer 30 includes a base polymer and an antistatic agent. The base polymer has a glass transition temperature of -50°C or lower and a dielectric constant of 5.0 or higher at 100 kHz. By using such a base polymer, an adhesive layer with a low surface resistance can be realized despite a low antistatic agent content. That is, in embodiments of the present invention, the antistatic agent content in the adhesive composition is less than 10 parts by weight per 100 parts by weight of the base polymer, while the surface resistance of the adhesive layer is 1.0 × 10⁻⁶. 9 The coefficient can be set to Ω / □ or less. As a result, it is possible to realize a polarizing plate that is thin, highly durable, has reduced appearance defects in the functional layer (e.g., iodine transmission suppression layer) contained in the polarizing plate, and has reduced cracking during shape processing.

[0011] The polarizer according to the embodiment of the present invention may further include functional layers other than the iodine transmission suppression layer. A typical example of such a functional layer is a phase difference layer. The optical properties (e.g., refractive index properties, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, and placement position of the phase difference layer can be appropriately set according to the purpose.

[0012] The polarizing plates according to embodiments of the present invention may be in the form of a single leaf or a long, rectangular shape. In this specification, "long, rectangular shape" means an elongated shape in which the length is sufficiently longer than the width, and for example, includes an elongated shape in which the length is 10 times or more, preferably 20 times or more, than the width. The long, rectangular polarizing plate can be wound into a roll.

[0013] A polarizing plate according to an embodiment of the present invention may have a shape other than rectangular. In this specification, "having a shape other than rectangular" means that the plan view shape of the polarizing plate is a shape other than rectangular. A typical example of a shape is a processed part that has been shaped. Therefore, a "polarizing plate having a shape other than rectangular" includes not only cases where the entire polarizing plate (i.e., the outer edge that defines the plan view shape of the film) is not rectangular, but also cases where a processed part is formed in a portion spaced inward from the outer edge of a rectangular polarizing plate. When using an adhesive layer with a low surface resistance (low-resistance adhesive layer), the added antistatic agent acts as a plasticizer, and cracks are likely to occur in the polarizer due to the shrinkage of the polarizing plate in such processed parts under high-temperature conditions. According to an embodiment of the present invention, such cracks can be significantly suppressed. Examples of shapes (processed parts) include through holes, chamfers on corners, and machined parts that become recesses when viewed from above. Typical examples of recesses include shapes that approximate a boat shape, shapes that approximate a bathtub shape, V-shaped notches, and U-shaped notches. Another example of a non-standard shape (non-standard processed part) is a shape corresponding to an automobile's instrument panel. This shape is formed in an arc shape along the rotation direction of the meter needle, and includes a portion of the outer edge that is convex inward in the surface direction in a V-shape (including a rounded shape). The non-standard shape is not limited to the above example, and any appropriate shape can be adopted depending on the purpose. For example, the shape of the through hole can be circular, elliptical, triangular, square, pentagonal, hexagonal, or octagonal. The through hole can also be provided at any appropriate position depending on the purpose. As shown in Figure 2, the through hole may be provided approximately in the center of the longitudinal end of a rectangular polarizing plate, at a predetermined position on the longitudinal end, at a corner of the polarizing plate, at the short end of a rectangular polarizing plate, or in the center of a polarizing plate that has a non-standard shape overall. The non-standard processed part may be formed by combining the above example forms. For example, a through hole may be formed by combining a V-shaped notch and / or a U-shaped notch.

[0014] The total thickness of the polarizing plate is preferably 60 μm or less, more preferably 55 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. The lower limit of the total thickness may be, for example, 28 μm. According to embodiments of the present invention, in a configuration having a low-resistance adhesive layer and a protective layer on only one side of the polarizer, the same effect as a configuration having protective layers on both sides of the polarizer can be obtained. As a result, one of the protective layers can be omitted, thus achieving a significant reduction in thickness. If the total thickness of the polarizing plate is within this range, the generation of bubbles known as delay bubbles can be significantly suppressed. Delay bubbles refer to bubbles that occur in the following situations. For example, when a polarizing plate with through holes is attached to the viewing side of an image display panel, a cover glass may be attached to the viewing side of the polarizing plate. The cover glass is attached by vacuum lamination via a predetermined adhesive. At this time, the through holes can be filled with the adhesive. Immediately after vacuum lamination, there are often no recognizable bubbles in the filled area. However, bubbles may occur during subsequent heat durability tests of the image display device. Typically, such bubbles can be generated when shrinkage stress from the polarizing plate is applied to the filled area. These bubbles are called delay bubbles. Delay bubbles are not minute, but large, occupying a certain percentage or more of the planar area of ​​the through-hole, and are unacceptable from both an appearance standpoint and a camera performance standpoint for the camera unit located at the position corresponding to the through-hole. Therefore, suppressing delay bubbles has high industrial value. Note that the total thickness of the polarizing plate refers to the sum of the thicknesses of the polarizer, protective layer, iodine transmission suppression layer, and adhesive or tack layer for laminating these (i.e., the total thickness of the polarizing plate does not include the thickness of the tack layer 30 and the release film that may be temporarily attached to its surface).

[0015] The components of a polarizing plate will be explained in more detail below.

[0016] B. Polarizer A polarizer is typically composed of a resin film containing a dichroic substance (typically iodine). Any suitable resin film that can be used as a polarizer can be employed. Typically, the resin film is a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film. The resin film may be a single layer or a laminate of two or more layers.

[0017] A specific example of a polarizer composed of a single layer of resin film is a PVA-based resin film that has been dyed with iodine and stretched (typically uniaxially stretched). The iodine dyeing is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio for uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA-based resin film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA-based resin film in water and washing it before dyeing can not only clean dirt and anti-blocking agents from the surface of the PVA-based film, but also swell the PVA-based resin film to prevent uneven dyeing.

[0018] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, preferably, the laminate is subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. This makes it possible to improve the optical properties of polarizers obtained through processing steps that involve immersing the laminate in liquid, such as dyeing and water-based stretching treatments. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer may be laminated onto the peeled surface according to the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0019] The thickness of the polarizer is preferably 1 μm to 10 μm, more preferably 1 μm to 8 μm, and even more preferably 2 μm to 5 μm. A polarizer thickness within this range can significantly contribute to the thinning of polarizing plates.

[0020] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is preferably 41.5% to 46.0%, more preferably 43.0% to 46.0%, and even more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0021] C. Protective layer The protective layer 12 (and any other protective layer, if present) is formed from any suitable film that can be used as a protective layer for the polarizer. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), and transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone are also acceptable. In addition, glassy polymers such as siloxane polymers can also be used. Polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As materials for this film, for example, a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains, and a thermoplastic resin having substituted or unsubstituted phenyl groups and nitrile groups in its side chains can be used. Examples include a resin composition having an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the above resin composition.

[0022] When the polarizing plate is positioned on the viewing side of the image display device, the protective layer 12 is typically positioned on that viewing side. In this case, the protective layer 12 may be subjected to surface treatments such as hard coating, anti-reflective coating, anti-sticking coating, or anti-glare coating, as needed.

[0023] The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 15 μm to 35 μm. If a surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

[0024] D. Iodine permeation suppression layer In embodiments of the present invention, by providing an iodine permeation suppression layer, it is possible to suppress the increase in the surface resistance value of the adhesive layer in high-temperature environments and / or high-temperature and high-humidity environments, and to suppress cracks during shape processing. As described above, the iodine permeation suppression layer is a solidified or thermoset product of a coating film of an organic solvent solution of resin. With such a configuration, the thickness can be made very thin (for example, 10 μm or less). The thickness of the iodine permeation suppression layer is preferably 0.05 μm to 10 μm, more preferably 0.08 μm to 5 μm, even more preferably 0.1 μm to 1 μm, and particularly preferably 0.2 μm to 0.7 μm. Furthermore, with such a configuration, the iodine permeation suppression layer can be formed directly on the polarizer (i.e., without an adhesive layer or adhesive layer). According to embodiments of the present invention, as described above, the polarizer and the iodine permeation suppression layer are very thin, and the adhesive layer or adhesive layer for laminating the iodine permeation suppression layer can be omitted, so the total thickness of the polarizer can be made extremely thin. Furthermore, such an iodine permeation-suppressing layer has the advantage of superior humidification resistance because it has lower hygroscopicity and moisture permeability compared to solidified aqueous coating films such as aqueous solutions or aqueous dispersions. As a result, it is possible to realize a highly durable polarizing plate that can maintain its optical properties even in high temperature and high humidity environments. In addition, such an iodine permeation-suppressing layer can suppress adverse effects on the polarizing plate (polarizer) due to ultraviolet irradiation compared to, for example, cured products of ultraviolet-curable resins. The iodine permeation-suppressing layer is preferably a solidified coating film of an organic solvent solution of resin. The solidified product has less shrinkage during film molding compared to the cured product, and does not contain residual monomers, etc., so deterioration of the film itself is suppressed, and adverse effects on the polarizing plate (polarizer) caused by residual monomers, etc. can be suppressed.

[0025] The glass transition temperature (Tg) of the resin constituting the iodine permeation suppression layer is typically 85°C or higher, preferably 90°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, and particularly preferably 120°C or higher. The upper limit of Tg may be, for example, 200°C. The weight-average molecular weight Mw of the resin is typically 25,000 or higher, preferably 30,000 or higher, more preferably 35,000 or higher, and even more preferably 40,000 or higher. The upper limit of Mw may be, for example, 150,000. If the Tg and Mw of the resin are within these ranges, the synergistic effect with the effect of composing the iodine permeation suppression layer as a solidified or thermoset product of a coating film of the resin's organic solvent solution can significantly suppress the transfer of iodine in the polarizer to the image display panel, even though it is very thin. As a result, when the polarizer is applied to an image display device, corrosion of the metal components of the image display device can be significantly suppressed.

[0026] Any suitable thermoplastic resin or thermosetting resin can be used as the resin constituting the iodine permeation suppression layer. A thermoplastic resin is preferred. Examples of thermoplastic resins include acrylic resins and epoxy resins. Acrylic resins and epoxy resins may also be used in combination. Representative examples of acrylic resins and epoxy resins that can be used in the iodine permeation suppression layer are described below.

[0027] Acrylic resins typically contain repeating units derived from (meth)acrylic acid ester monomers having a linear or branched structure as their main component. In this specification, (meth)acrylic means acrylic and / or methacrylic. Acrylic resins may contain repeating units derived from any suitable copolymer monomer depending on the purpose. Examples of copolymer monomers include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic vinyl monomers. By appropriately setting the type, number, combination, and copolymerization ratio of monomer units, an acrylic resin having the above-mentioned predetermined Mw can be obtained.

[0028] <Boron-containing acrylic resin> In one embodiment, the acrylic resin includes a copolymer (hereinafter sometimes referred to as a boron-containing acrylic resin) obtained by polymerizing a monomer mixture containing more than 50 parts by weight of a (meth)acrylic monomer and more than 0 part by weight and less than 50 parts by weight of a monomer represented by formula (1) (hereinafter sometimes referred to as a copolymerizable monomer): [Chemical formula] (In the formula, X represents a functional group containing at least one reactive group selected from the group consisting of a vinyl group, a (meth)acrylic group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group, R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent, R 1 and R<l 2 may be linked to each other to form a ring).

[0029] The boron-containing acrylic resin typically has a repeating unit represented by the following formula. By polymerizing a monomer mixture containing the copolymerizable monomer represented by formula (1) and a (meth)acrylic monomer, the boron-containing acrylic resin has a substituent containing boron in the side chain (for example, the repeating unit of k in the following formula). Thereby, when the iodine permeation suppressing layer is disposed adjacent to the polarizer, the adhesion to the polarizer can be improved. This boron-containing substituent may be contained continuously (i.e., in a block form) in the boron-containing acrylic resin or may be contained randomly. [Chemical formula] (In the formula, R 6 represents an arbitrary functional group, and j and k represent integers of 1 or more).

[0030] <(meth)acrylic monomers> Any suitable (meth)acrylic monomer can be used as the (meth)acrylic monomer. Examples include (meth)acrylic acid ester monomers having a linear or branched structure, and (meth)acrylic acid ester monomers having a cyclic structure.

[0031] Examples of (meth)acrylic acid ester monomers having a linear or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, methyl 2-ethylhexyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Methyl (meth)acrylate is preferably used. Only one (meth)acrylic acid ester monomer may be used, or two or more may be used in combination.

[0032] Examples of (meth)acrylic acid ester monomers having a cyclic structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxyethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethyl Examples of biphenyl group-containing monomers include oxy-2-hydroxypropyl (meth)acrylate, p-biphenyloxy-2-hydroxypropyl (meth)acrylate, m-biphenyloxy-2-hydroxypropyl (meth)acrylate, N-(meth)acryloyloxyethyl-o-biphenyl=carbamate, N-(meth)acryloyloxyethyl-p-biphenyl=carbamate, N-(meth)acryloyloxyethyl-m-biphenyl=carbamate, o-phenylphenol glycidyl ether acrylate, terphenyl (meth)acrylate, o-terphenyloxyethyl (meth)acrylate, etc. Preferably, 1-adamantyl (meth)acrylate and dicyclopentanyl (meth)acrylate are used. By using these monomers, polymers with high glass transition temperatures can be obtained. These monomers may be used individually or in combination of two or more.

[0033] Furthermore, instead of the (meth)acrylic acid ester monomers mentioned above, silsesquioxane compounds having a (meth)acryloyl group may be used. By using silsesquioxane compounds, acrylic polymers with high glass transition temperatures can be obtained. Silsesquioxane compounds are known to have various skeletal structures, such as cage structures, ladder structures, and random structures. Silsesquioxane compounds may have only one of these structures, or two or more. Silsesquioxane compounds may be used alone, or two or more may be used in combination.

[0034] As silsesquioxane compounds containing a (meth)acryloyl group, for example, the MAC grade and AC grade of the SQ series from Toagosei Co., Ltd. can be used. MAC grade is a silsesquioxane compound containing a methacryloyl group, and specifically, examples include MAC-SQ TM-100, MAC-SQ SI-20, MAC-SQ HDM, etc. AC grade is a silsesquioxane compound containing an acryloyl group, and specifically, examples include AC-SQ TA-100, AC-SQ SI-20, etc.

[0035] The (meth)acrylic monomer is used in amounts exceeding 50 parts by weight per 100 parts by weight of the monomer mixture.

[0036] <Copolymer Monomers> The monomer represented by formula (1) above is used as the copolymer monomer. By using such a copolymer monomer, a substituent containing boron is introduced into the side chain of the resulting polymer. Only one copolymer monomer may be used, or two or more types may be used in combination.

[0037] Examples of the aliphatic hydrocarbon group in formula (1) above include linear or branched alkyl groups having 1 to 20 carbon atoms, which may have substituents, cyclic alkyl groups having 3 to 20 carbon atoms, which may have substituents, and alkenyl groups having 2 to 20 carbon atoms. Examples of the aryl group above include phenyl groups having 6 to 20 carbon atoms, which may have substituents, and naphthyl groups having 10 to 20 carbon atoms, which may have substituents. Examples of the heterocyclic group include five-membered or six-membered ring groups containing at least one heteroatom, which may have substituents. 1 and R 2 They may be connected to each other to form a ring. 1 and R 2 This is preferably a hydrogen atom, or a linear or branched alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

[0038] The reactive group contained in the functional group represented by X is at least one selected from the group consisting of vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, hydroxyl group, amino group, aldehyde group, and carboxyl group. Preferably, the reactive group is a (meth)acrylic group and / or a (meth)acrylamide group. Having these reactive groups can further improve adhesion to the polarizer when the iodine transmission suppression layer is placed adjacent to the polarizer.

[0039] In one embodiment, the functional group represented by X is preferably a functional group represented by ZY-. Here, Z represents a functional group comprising at least one reactive group selected from the group consisting of vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, hydroxyl group, amino group, aldehyde group, and carboxyl group, and Y represents a phenylene group or alkylene group.

[0040] Specifically, the following compounds can be used as copolymer monomers. [ka] [ka]

[0041] The copolymer monomer is used in an amount greater than 0 parts by weight and less than 50 parts by weight per 100 parts by weight of the monomer mixture. Preferably, it is 0.01 parts by weight or more and less than 50 parts by weight, more preferably 0.05 parts by weight to 20 parts by weight, even more preferably 0.1 parts by weight to 10 parts by weight, and particularly preferably 0.5 parts by weight to 5 parts by weight.

[0042] <Acrylic resin containing lactone rings, etc.> In another embodiment, the acrylic resin may have repeating units containing a ring structure selected from lactone ring units, glutaric acid anhydride units, glutarimide units, maleic acid anhydride units, and maleimide (N-substituted maleimide) units. The repeating units containing a ring structure may consist of only one type, or two or more types. The content of repeating units containing a ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and even more preferably 20 mol% to 30 mol%. The acrylic resin contains repeating units derived from the above-mentioned (meth)acrylic monomer as the main repeating units.

[0043] <Epoxy resin> Preferably, an epoxy resin having an aromatic ring is used as the epoxy resin. By using an epoxy resin having an aromatic ring as the epoxy resin, the adhesion to the polarizer can be improved when the iodine permeation suppression layer is placed adjacent to the polarizer. Furthermore, when the adhesive layer is placed adjacent to the iodine permeation suppression layer, the anchoring force of the adhesive layer can be improved. Examples of epoxy resins having an aromatic ring include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol; naphthol type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin. Preferably, bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin are used. Epoxy resin may be used alone, or two or more types may be used in combination.

[0044] The iodine permeation-inhibiting layer can be formed by applying an organic solvent solution of the resin as described above to form a coating film, and then solidifying or thermally curing the coating film. Any appropriate method and conditions can be used for the application method, solidification, or curing conditions.

[0045] The iodine permeation suppression layer (essentially, an organic solvent solution of the above-mentioned resin) may contain any suitable additives depending on the purpose. The type, number, combination, and amount of additives can be appropriately determined depending on the purpose.

[0046] E. Adhesive layer The surface resistance of the adhesive layer 30 is 1.0 × 10⁻⁶, as described above. 9 It is less than or equal to Ω / □, preferably 5.0 × 10 8 It is less than or equal to Ω / □, and more preferably 1.0 × 10 8 It is less than or equal to Ω / □, and more preferably 7.0 × 10 7 It is less than or equal to Ω / □, and particularly preferably 1.0 × 10⁻⁶. 7 It is less than or equal to Ω / □. The lower limit of the surface resistance is, for example, 5.0 × 10 5 It may be less than or equal to Ω / □. As described above, according to the embodiments of the present invention, an adhesive layer with a low surface resistance can be realized despite a low content of antistatic agent.

[0047] The adhesive strength of the adhesive layer to the glass is preferably 1.0 N / 25 mm or more, more preferably 1.5 N / 25 mm or more, and even more preferably 2.0 N / 25 mm or more. When the adhesive strength is within this range, excellent adhesion to the image display panel and excellent reworkability are achieved. The upper limit of the adhesive strength may be, for example, 6.0 N / 25 mm.

[0048] The thickness of the adhesive layer is preferably 2 μm to 55 μm, more preferably 2 μm to 30 μm, even more preferably 5 μm to 25 μm, and particularly preferably 10 μm to 20 μm.

[0049] The adhesive composition constituting the adhesive layer includes a base polymer and an antistatic agent, as described above. The glass transition temperature (Tg) of the base polymer is -50°C or lower, preferably -52°C or lower, and more preferably -55°C or lower, as described above. The lower limit of the Tg of the base polymer may be, for example, -75°C. The dielectric constant of the base polymer at 100 kHz is 5.0 or higher, preferably 5.5 or higher, more preferably 6.0 or higher, even more preferably 6.5 or higher, and particularly preferably 7.0 or higher, as described above. The upper limit of the dielectric constant of the base polymer may be, for example, 10.0. By using such a base polymer, an adhesive layer with low surface resistance can be realized despite a low antistatic agent content. The Tg of the base polymer can be calculated as the Tg of the polymer converted from the Tg of each monomer component using the polymerization ratio.

[0050] Examples of base polymers include (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. Preferably, it is a (meth)acrylic polymer. In this specification, a (meth)acrylic polymer as a base polymer may be referred to as a (meth)acrylic base polymer.

[0051] (Meth)acrylic-based polymers preferably contain alkoxy group-containing monomers as monomer components. Examples of alkoxy group-containing monomers include monomers represented by the following formula: [ka] In the formula, R 1is an alkyl group, for example, a methyl group or an ethyl group, and n is an integer from 1 to 15. As is clear from the above formula, the alkoxy group is preferably linear. If the alkoxy group is linear, the Tg of the resulting (meth)acrylic base polymer can be set to the desired range, and the dielectric constant of the base polymer can be set to the desired range. Base polymers containing monomers having a ring structure may have an excessively high Tg and / or an excessively low dielectric constant. Specific examples of alkoxy group-containing monomers include methoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination of two or more. By using alkoxy group-containing monomers as monomer components, a base polymer with a desired Tg and dielectric constant can be obtained. As a result, an adhesive layer with low surface resistance can be realized despite a low antistatic agent content. The content of alkoxy group-containing monomers in the base polymer is preferably 30 to 99 parts by weight per 100 parts by weight of the total monomer components. The content of alkoxy group-containing monomers may be, for example, 30 to 60 parts by weight, or 30 to 50 parts by weight, or 50 to 99 parts by weight, or 60 to 99 parts by weight.

[0052] The (meth)acrylic base polymer preferably contains a hydroxyl group-containing monomer as a monomer component. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. From the viewpoint of improving the durability of the adhesive layer, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred. The content of the hydroxyl group-containing monomer in the base polymer is preferably 1 to 5 parts by weight, more preferably 1 to 3 parts by weight, per 100 parts by weight of the total monomer components.

[0053] (Meth)acrylic base polymers may contain alkyl (meth)acrylate as a monomer component. Examples of alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. Alkyl (meth)acrylate can be used alone or in combination. The average number of carbon atoms in the alkyl group is preferably 3 to 8, more preferably 3 to 6. The content of alkyl (meth)acrylate in the base polymer can be arbitrarily set as the remainder of the monomer components other than the alkyl (meth)acrylate.

[0054] The (meth)acrylic base polymer may optionally further contain other monomer components (copolymer monomers). Typical examples of copolymer monomers include aromatic hydrocarbon group-containing monomers (e.g., phenyl(meth)acrylate, phenoxyethyl(meth)acrylate, benzyl(meth)acrylate), carboxyl group-containing monomers (e.g., (meth)acrylic acid, carboxyethyl(meth)acrylate, carboxypentyl(meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid), amino group-containing monomers (e.g., N,N-dimethylaminoethyl(meth)acrylate), and amide group-containing monomers (e.g., (meth)acrylamide). Examples include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, nitrile group-containing monomers (e.g., (meth)acrylonitrile), polyfunctional monomers (e.g., hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate), epoxy group-containing monomers (e.g., glycidyl(meth)acrylate), and heterocyclic monomers (e.g., acryloylmorpholine). The type, number, combination, and amount (content) of copolymer monomers can be appropriately determined depending on the purpose.

[0055] The weight-average molecular weight Mw of the (meth)acrylic-based polymer is preferably 1 million to 3 million, more preferably 2 million to 3 million, and even more preferably 2 million to 2.8 million. If the weight-average molecular weight Mw is less than 1 million, crack suppression may be insufficient. If the weight-average molecular weight Mw exceeds 3 million, viscosity may increase and / or gelation may occur during polymer polymerization.

[0056] Typical examples of antistatic agents include inorganic cationic salts and organic cationic salts.

[0057] Inorganic cationic salts are specifically inorganic cation-anionic salts. Typical cations constituting the cation portion of an inorganic cationic salt include alkali metal ions. Specific examples include lithium ions, sodium ions, and potassium ions. Lithium ions are preferred. Therefore, a preferred inorganic cationic salt is a lithium salt.

[0058] Examples of anions that make up the anionic part of an inorganic cation salt include Cl - , Br - , I - AlCl4 - Al2Cl7 - BF4 - PF6 - ClO4 - NO3 - CH3COO - CF3COO - CH3SO3 - CF3SO3 - , (CF3SO2)3C - AsF6 - SbF6 - , NbF6 - TaF6 - , (CN)2N - , C4F9SO3 - C3F7COO - (CF3SO2)(CF3CO)N - , - O3S(CF2)3SO3 - , and the following general formulas (1) to (4) (1):(C n F 2n+1 SO2)2N - (n is an integer between 1 and 10) (2):CF2(C m F 2m SO2)2N - (m is an integer between 1 and 10) (3): - O3S(CF2) l SO3 - (l is an integer from 1 to 10) (4):(C p F 2p+1 SO2)N- (C q F 2q+1 SO2), (p, q are integers from 1 to 10), Anions represented by are examples. Fluorine-containing anions are preferred, and fluorine-containing imide anions are more preferred.

[0059] Examples of fluorine-containing imide anions include imide anions having a perfluoroalkyl group. A specific example is (CF3SO2)(CF3CO)N. - , as well as general formulas (1), (2) and (4) (1):(C n F 2n+1 SO2)2N - (n is an integer between 1 and 10) (2):CF2(C m F 2m SO2)2N - (m is an integer between 1 and 10) (4):(C p F 2p+1 SO2)N - (C q F 2q+1 SO2), (p, q are integers from 1 to 10), Anions represented by can be cited. Preferably, (CF3SO2)2N - , (C2F5SO2)2N - (Perfluoroalkylsulfonyl)imides represented by general formula (1), more preferably (CF3SO2)2N - This is a bis(trifluoromethanesulfonyl)imide represented by . Therefore, a preferred inorganic cationic salt that can be used in embodiments of the present invention is lithium bis(trifluoromethanesulfonyl)imide.

[0060] Organic cationic salts are specifically organic cation-anionic salts. Typical cations constituting the cationic portion of organic cationic salts include organic onium, which is formed by substitution with an organic group to create an onium ion. Examples of onium in organic onium include nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium. Preferably, nitrogen-containing onium and sulfur-containing onium are used. Examples of nitrogen-containing onium include ammonium cation, piperidinium cation, pyrrolidinium cation, pyridinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, and pyrazolinium cation. Examples of sulfur-containing onium include sulfonium cations. Examples of phosphorus-containing onium include phosphonium cations. Examples of organic groups in organic onium include alkyl groups, alkoxyl groups, and alkenyl groups. Specific examples of preferred organooniums include tetraalkylammonium cations (e.g., tributylmethylammonium cations), alkylpiperidinium cations, and alkylpyrrolidinium cations. The anions constituting the anionic portion of the organic cationic salt are as described with respect to the anions constituting the anionic portion of the inorganic cation. Preferred organic cationic salts that can be used in embodiments of the present invention are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

[0061] Inorganic cation salts and organic cation salts may be used in combination.

[0062] The content of the antistatic agent in the adhesive composition is less than 10 parts by weight, preferably 7 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 3 parts by weight or less, per 100 parts by weight of the base polymer, as described above. According to embodiments of the present invention, an adhesive layer with a low surface resistance can be realized despite such a low content of antistatic agent. The lower limit of the antistatic agent content may be, for example, 0.5 parts by weight. If the content of the antistatic agent is too low, the desired surface resistance may not be obtained.

[0063] Adhesive compositions typically contain a silane coupling agent, a crosslinking agent, and / or an antioxidant. Typical silane coupling agents include functional group-containing silane coupling agents. Examples of functional groups include epoxy groups, mercapto groups, amino groups, isocyanate groups, isocyanurate groups, vinyl groups, styryl groups, acetoacetyl groups, ureido groups, thiourea groups, (meth)acrylic groups, heterocyclic groups, acid anhydride groups, and combinations thereof. Functional group-containing silane coupling agents can be used alone or in combination. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Crosslinking agents can also be used alone or in combination. The inclusion of a silane coupling agent offers the following advantages: Adhesive compositions using base polymers containing alkoxy group-containing monomers tend to be highly polar, which can result in insufficient adhesion to non-polar substrates. The inclusion of a silane coupling agent allows for sufficient adhesion to various substrates and suppresses peeling. Furthermore, the inclusion of an antioxidant offers the following advantages. Base polymers containing alkoxy group-containing monomers have a lower Tg and become softer. By including antioxidants, shrinkage due to oxidative degradation from the polarizing plate edge and adhesive layer edge can be suppressed.

[0064] The adhesive composition may contain additives. Specific examples of additives include powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulate matter, and foil-like materials. Furthermore, a redox system with a reducing agent may be employed within a controllable range. The type, number, combination, and content of additives can be appropriately determined depending on the purpose.

[0065] F. Image display device The polarizing plates described in sections A to E above can be applied to image display devices. Therefore, embodiments of the present invention encompass image display devices using such polarizing plates. Typical examples of image display devices include liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays, inorganic EL displays). In one embodiment, the image display device is a narrow-bezel (preferably bezel-less) image display device or an in-cell type image display device. The effects of embodiments of the present invention are particularly pronounced in such image display devices. [Examples]

[0066] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.

[0067] (1) Thickness Thicknesses of 10 μm or less were measured using an interferometer (Otsuka Electronics Co., Ltd., product name "MCPD-3000"). Thicknesses exceeding 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C").

[0068] (2) Surface resistance The resistance of the adhesive layer surface of the polarizing plates (polarizing plates with adhesive layer) obtained in the examples and comparative examples was measured using an MCP-HT450 manufactured by Mitsubishi Chemical Analytec Co., Ltd., and was defined as the initial resistance value. Furthermore, the polarizing plates with adhesive layer were subjected to reliability tests under two different conditions (500 hours in an environment of 85°C and 500 hours in an environment of 60°C and 95%RH), and the resistance value was measured in the same manner as above. The resistance increase rate was calculated using the following formula. Resistance increase rate (%) = {(Resistance after reliability test - Initial resistance) / Initial resistance} × 100 Furthermore, the following criteria were used for evaluation. ○: Resistance increase rate is less than 50% △: Resistance increase rate is 50% or more but less than 1000% ×: Resistance increase rate is 1000% or more

[0069] (3) ESD test The polarizing plates (polarizing plates with adhesive layer) obtained in the examples and comparative examples were cut to 70 mm x 150 mm and bonded to a liquid crystal panel via the adhesive layer. Next, silver paste was applied to the side surface of the bonded polarizing plate with adhesive layer, covering the entire thickness of the side surface, and connected to an external ground electrode. Then, an ESD (ESD-8012A, manufactured by SANKI Corporation) (applied voltage 15 kV) was used to generate electrostatic discharge (applied) on the surface of the polarizing plate a total of 10 times at 1-second intervals, drawing a circle on the surface of the polarizing plate, to cause alignment disturbance of the liquid crystals in the liquid crystal panel. The time until the white areas caused by the electricity disappeared was measured and evaluated according to the following criteria. ○: White areas disappeared within 5 seconds. △: White areas disappeared within 10 seconds. ×: White gaps remained for more than 10 seconds.

[0070] (4) Delayable A 3.9 mm diameter through-hole was formed in the corner of the polarizing plates obtained in the examples and comparative examples using an end mill. This polarizing plate was bonded to a glass plate via an adhesive layer to obtain a polarizing plate / glass plate laminate A. On the other hand, a standard optical adhesive sheet was bonded to a cover glass (manufactured by Matsunami Glass Co., Ltd., 0.8 mm thick) using a roll laminator to obtain a cover glass / optical adhesive laminate B. Laminates A and B were pressed together using a vacuum laminator so that the polarizing plate of laminate A and the optical adhesive of laminate B faced each other, and the through-hole was filled with optical adhesive. In this way, an image display device compatible product was manufactured. After autoclaving the obtained image display device compatible product, it was subjected to a heating test (85°C, 24 h), and the state of bubbles after the test was observed visually or with an optical microscope and evaluated according to the following criteria. ○: No air bubbles were observed in the filling area. ×: Air bubbles were observed in the filling area.

[0071] (5) Discoloration From the polarizers obtained in the examples and comparative examples, test specimens (50 mm × 50 mm) were cut out with two opposing sides oriented in the direction perpendicular to the absorption axis and the direction perpendicular to the absorption axis, respectively. The test specimens were bonded to a glass plate via an adhesive layer, and humidified by leaving them in an oven at 65°C and 90% RH for 120 hours. The state of color loss at the edges of the humidified polarizer (essentially the polarizer) was examined using a microscope when placed in a crossed nicol state with a standard polarizer. Specifically, the amount of color loss (color loss amount: μm) from the edges of the polarizer was measured. An Olympus MX61L microscope was used, and the amount of color loss at the corners was measured from images taken at 10x magnification.

[0072] (6) Exterior The polarizing plates obtained in the examples and comparative examples (cut to a size of 50 mm x 50 mm) were subjected to reliability tests (72 hours in an environment of 65°C and 90% RH). After that, their appearance (the overall appearance of the polarizing plate, including the expansion of the protective layer and the state of the iodine permeation suppression layer) was visually observed and evaluated according to the following criteria. ○: No swelling, peeling, cracking, or foreign matter was observed. △: Swelling, peeling, cracks, or foreign matter were observed in several places. ×: Numerous instances of swelling, peeling, cracks, or foreign matter were observed throughout.

[0073] (7) Cracks in the irregularly shaped parts A 3.9 mm diameter through-hole was formed in the corner of the polarizing plates obtained in the examples and comparative examples using an end mill. The polarizing plates with the through-holes were bonded to a glass plate via an adhesive layer to create test samples. These test samples were subjected to a heat shock test, in which the temperature was maintained at 85°C for 30 minutes, followed by a maintenance temperature of -40°C for 30 minutes, repeated 300 times. The appearance of the through-hole area after the test was visually observed and evaluated according to the following criteria. In all examples and comparative examples, no adhesive chipping (a phenomenon in which the edges of the adhesive layer are damaged) occurred. ○: No cracks were found. ×: Cracks were observed.

[0074] [Manufacturing Example 1: Preparation of (meth)acrylic-based polymer A1] A monomer mixture containing 39 parts butyl acrylate (BA), 60 parts methoxyethyl acrylate (MEA), and 1 part 4-hydroxybutyl acrylate (4HBA) was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile was added to 100 parts of this monomer mixture as a polymerization initiator along with 100 parts ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at approximately 55°C to prepare a solution of (meth)acrylic-based polymer A1. The Tg and dielectric constant of (meth)acrylic-based polymer A1 are shown in Table 1. The dielectric constant was measured by a conventional method. The Tg was calculated by converting the Tg of each monomer using the polymerization ratio.

[0075] [Manufacturing Example 2: Preparation of (meth)acrylic-based polymer A2] A solution of (meth)acrylic-based polymer A2 was prepared in the same manner as in Production Example 1, except that 60 parts of ethoxyethoxyethyl acrylate (EEEA) were used instead of 60 parts of MEA. The Tg and dielectric constant of (meth)acrylic-based polymer A2 are shown in Table 1.

[0076] [Manufacturing Example 3: Preparation of (meth)acrylic-based polymer A3] A solution of (meth)acrylic-based polymer A3 was prepared in the same manner as in Production Example 1, except that 60 parts of methoxytriethylene glycol acrylate (MTGA) were used instead of 60 parts of MEA. The Tg and dielectric constant of (meth)acrylic-based polymer A3 are shown in Table 1.

[0077] [Manufacturing Example 4: Preparation of (meth)acrylic-based polymer A4] A solution of (meth)acrylic-based polymer A4 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 99 parts MTGA and 1 part 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A4 are shown in Table 1.

[0078] [Manufacturing Example 5: Preparation of (meth)acrylic-based polymer A5] A solution of (meth)acrylic-based polymer A5 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 49 parts of BA, 50 parts of MTGA, and 1 part of 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A5 are shown in Table 1.

[0079] [Manufacturing Example 6: Preparation of (meth)acrylic-based polymer A6] A solution of (meth)acrylic-based polymer A6 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 69 parts BA, 30 parts MTGA, and 1 part 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A6 are shown in Table 1.

[0080] [Manufacturing Example 7: Preparation of (meth)acrylic-based polymer A7] A solution of (meth)acrylic-based polymer A7 was prepared in the same manner as in Production Example 5, except that 50 parts of methoxypolyethylene glycol acrylate (MPEA) were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A7 are shown in Table 1.

[0081] [Manufacturing Example 8: Preparation of (meth)acrylic-based polymer A8] A solution of (meth)acrylic-based polymer A8 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 79 parts of BA, 20 parts of MEA, and 1 part of 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A8 are shown in Table 1.

[0082] [Production Example 9: Preparation of (meth)acrylic-based polymer A9] A solution of (meth)acrylic-based polymer A9 was prepared in the same manner as in Production Example 5, except that 50 parts of phenoxyethyl acrylate (PEA) were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A9 are shown in Table 1.

[0083] [Manufacturing Example 10: Preparation of (meth)acrylic-based polymer A10] A solution of (meth)acrylic-based polymer A10 was prepared in the same manner as in Production Example 5, except that 50 parts of tetrahydrofurfuryl acrylate were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A10 are shown in Table 1.

[0084] [Manufacturing Example 11: Preparation of (meth)acrylic-based polymer A11] A solution of (meth)acrylic-based polymer A11 was prepared in the same manner as in Production Example 5, except that 50 parts of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A11 are shown in Table 1.

[0085] [Manufacturing Example 12: Preparation of (meth)acrylic-based polymer A12] A solution of (meth)acrylic-based polymer A12 was prepared in the same manner as in Production Example 5, except that 50 parts of (3-ethyloxetan-3-yl)methyl acrylate were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A12 are shown in Table 1.

[0086] [Manufacturing Example 13: Preparation of (meth)acrylic-based polymer A13] A solution of (meth)acrylic-based polymer A13 was prepared in the same manner as in Production Example 5, except that 50 parts of cyclic trimethylolpropane formal acrylate were used instead of 50 parts of MTGA. The Tg and dielectric constant of (meth)acrylic-based polymer A13 are shown in Table 1.

[0087] [Manufacturing Example 14: Preparation of (meth)acrylic-based polymer A14] A solution of (meth)acrylic-based polymer A14 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 80.3 parts of BA, 0.2 parts of acrylic acid (AA), 16 parts of PEA, 3 parts of N-vinylpyrrolidone (NVP), and 0.5 parts of 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A14 are shown in Table 1.

[0088] [Manufacturing Example 15: Preparation of (meth)acrylic-based polymer A15] A solution of (meth)acrylic-based polymer A15 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 99 parts of BA and 1 part of 4HBA was used. The Tg and dielectric constant of (meth)acrylic-based polymer A15 are shown in Table 1.

[0089] [Manufacturing Example 16: Fabrication of Polarizing Plate P1] 1. Fabrication of a polarizer As the thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length, with a water absorption rate of 0.75% and a Tg of approximately 75°C was used. One side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer Z410") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be a predetermined value (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the laminate was dried in an oven maintained at 90°C while being brought into contact with a SUS (stainless steel) heated roll with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

[0090] 2. Fabrication of polarizing plates An HC-TAC film was bonded as a protective layer to the surface of the polarizer obtained above (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. Specifically, the curing adhesive was applied to a total thickness of 1.0 μm and bonded using a roll machine. Then, UV light was irradiated from the protective layer side to cure the adhesive. The HC-TAC film is a film in which a hard coat (HC) layer (7 μm thick) is formed on a triacetylcellulose (TAC) film (25 μm thick), and it was bonded so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off, and an iodine permeability suppression layer (0.3 μm thick) was formed on the peeled surface. The iodine permeability suppression layer was formed as follows. 97.0 parts of methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Methyl Methacrylate Monomer"), 3.0 parts of the copolymer monomer represented by the above general formula (1e), and 0.2 parts of polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "2,2'-Azobis(Isobutyronitrile)") were dissolved in 200 parts of toluene. Then, the polymerization reaction was carried out for 5.5 hours while heating at 70°C under a nitrogen atmosphere to obtain a boron-containing acrylic resin solution (solid content concentration: 33%). The obtained boron-containing acrylic polymer had a Tg of 110°C and a Mw of 80000. 20 parts of this boron-containing acrylic polymer were dissolved in 80 parts of methyl ethyl ketone to obtain a resin solution (20%). This resin solution was applied to the peeling surface of the above resin substrate using a wire bar, and the coated film was dried at 60°C for 5 minutes to form an iodine permeation suppression layer composed of the solidified organic solvent solution of the resin coated film. In this way, a polarizing plate P1 having the following configuration was obtained: protective layer (HC layer / TAC film) / adhesive layer / polarizer / iodine transmission suppression layer.

[0091] [Manufacturing Example 17: Fabrication of Polarizing Plate P2] A 30 μm thick polyvinyl alcohol film was stretched to 3 times its original thickness while being stained for 1 minute in a 0.3% iodine solution at 30°C between rolls with different speed ratios. Then, it was stretched to a total stretching ratio of 6 times while being immersed for 0.5 minutes in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C. Next, it was washed by immersion for 10 seconds in an aqueous solution containing 1.5% potassium iodide at 30°C, and then dried at 50°C for 4 minutes to obtain a 12 μm thick polarizer. An HC-TAC film was laminated to one side of the polarizer in the same manner as in Production Example 15. Furthermore, an acrylic film (20 μm thick) having a lactone ring structure was laminated to the other side of the polarizer via an ultraviolet-curing adhesive (1.0 μm thick). Finally, an iodine permeability suppression layer (0.3 μm thick) was formed on the surface of the acrylic film in the same manner as in Production Example 16. In this way, a polarizing plate P2 having the following configuration was obtained: protective layer (HC layer / TAC film) / adhesive layer / polarizer / adhesive layer / protective layer (acrylic film) / iodine transmission suppression layer.

[0092] [Manufacturing Example 18: Fabrication of Polarizing Plate P3] Polarizing plate P3 was obtained in the same manner as in Manufacturing Example 17, except that a cyclic olefin resin (COP) film (thickness 13 μm) was used instead of acrylic film.

[0093] [Example 1] 1. Preparation of adhesive composition To 100 parts of the solids content of the (meth)acrylic-based polymer A1 solution obtained in Production Example 1, 3 parts of an antistatic agent (product name: LiTFSi30EA, manufactured by Mitsubishi Materials Corporation), 0.3 parts of benzoyl peroxide as a crosslinking agent (product name: Niper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.), 0.2 parts of an isocyanate-based crosslinking agent (product name: Takenate D110N, manufactured by Mitsui Chemicals, Inc.), 0.03 parts of a rework improver (product name: Cyril SAT10, manufactured by Kaneka Corporation), 0.3 parts of an antioxidant (product name: Irganox 1010, hindered phenol type, manufactured by BASF Japan), and 0.2 parts of a silane coupling agent (product name: A-100, manufactured by Soken Chemical Co., Ltd., acetoacetyl group-containing silane coupling agent) were added to prepare a solution of an acrylic adhesive composition.

[0094] 2. Fabrication of polarizing plates with adhesive layer A solution of the acrylic adhesive composition obtained above was applied to one side of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Films, trade name "MRF38", separator film) treated with a silicone release agent, so that the thickness of the adhesive layer after drying would be 15 μm. The film was dried at 155°C for 1 minute to form an adhesive layer on the surface of the separator film. Next, the adhesive layer formed on the separator film was transferred to the surface of the iodine transmission suppression layer of polarizing plate P1 prepared in Production Example 16 to produce a polarizing plate with an adhesive layer. The obtained polarizing plate with an adhesive layer was subjected to the evaluations described in (2) to (7) above. The results are shown in Table 1.

[0095] [Examples 2-24 and Comparative Examples 1-12] Polarizing plates with adhesive layers were fabricated using the polarizing plate and adhesive layer combinations shown in Table 1. The results are shown in Table 1. The abbreviations for the antistatic agents in Table 1 are as follows. LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide EMI-FSI: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide TBMA-TFSI: Tributylmethylammonium bis(trifluoromethanesulfonyl)imide

[0096] [Table 1]

[0097] [evaluation] As is clear from Table 1, the polarizing plates of the embodiments of the present invention showed good results in ESD testing and maintained low surface resistance values ​​even after reliability testing. Furthermore, the polarizing plates of the embodiments of the present invention showed good suppression of delay bubbles, discoloration during humidification, appearance defects after reliability testing, and cracks during shaping. [Industrial applicability]

[0098] The polarizing plate of the present invention is suitably used in image display devices such as liquid crystal displays, organic EL displays, and inorganic EL displays. [Explanation of Symbols]

[0099] 11 Polarizer 12 Protective layer 30 Adhesive layer 40 Iodine permeation suppression layer 100 polarizing plates

Claims

1. a polarizer, a protective layer provided on one side of the polarizer, an iodine permeation suppression layer provided on the other side of the polarizer, and a pressure-sensitive adhesive layer provided on the side of the iodine permeation suppression layer opposite to the polarizer, the iodine permeation suppression layer is a solidified or thermoset product of a coating film of a resin solution in an organic solvent, the PSA composition constituting the PSA layer contains a base polymer and an antistatic agent, the base polymer has a glass transition temperature of −50° C. or lower and a dielectric constant at 100 kHz of 5.0 or higher; The surface resistance of the pressure-sensitive adhesive layer is 1.0 × 10 ９ Ω / □ or less, Polarizing plate.

2. The polarizing plate according to claim 1 , wherein the base polymer contains an alkoxy group-containing monomer as a monomer component.

3. 3. The polarizing plate according to claim 2, wherein the base polymer contains 20 to 99 parts by weight of the alkoxy group-containing monomer with respect to 100 parts by weight of the total monomer components.

4. The polarizing plate according to claim 3 , wherein the alkoxy group-containing monomer is represented by the following formula: 【Chemistry 1】 In the formula, R １ is an alkyl group, and n is an integer from 1 to 15.

5. The polarizing plate according to claim 4 , wherein the base polymer further comprises a hydroxyl group-containing monomer as a monomer component.

6. 6. The polarizing plate according to claim 1, wherein the content of the antistatic agent in the pressure-sensitive adhesive composition is 10 parts by weight or less with respect to 100 parts by weight of the base polymer.

7. 7. The polarizing plate according to claim 1, wherein the antistatic agent comprises lithium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, or tributylmethylammonium bis(trifluoromethanesulfonyl)imide.

8. The polarizing plate according to claim 1 , wherein the pressure-sensitive adhesive composition further contains a silane coupling agent.

9. The polarizing plate according to claim 1 , wherein the pressure-sensitive adhesive composition further comprises an antioxidant.

10. 10. The polarizing plate according to claim 1, wherein the adhesive strength of the adhesive layer to glass is 1.0 N / 25 mm or more.

11. The polarizing plate according to any one of claims 1 to 10, wherein the resin constituting the iodine permeation suppressing layer contains a copolymer obtained by polymerizing a monomer mixture containing more than 50 parts by weight of a (meth)acrylic monomer and more than 0 part by weight and less than 50 parts by weight of a monomer represented by formula (1): 【Chemistry 2】 (wherein X represents a functional group containing at least one reactive group selected from the group consisting of a vinyl group, a (meth)acrylic group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group; R １ and R ２ each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aryl group, or an optionally substituted heterocyclic group; R １ and R ２ may be linked to each other to form a ring).

12. 12. The polarizing plate according to claim 1, having a total thickness of 60 μm or less.

13. An image display device comprising the polarizing plate according to claim 1 .

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