Polarizing plate and image display device using the polarizing plate

Abstract

To provide a polarizing plate which is thin and has a through hole, suppresses air bubbles when the through hole is filled with an adhesive, is excellent in reliability under a high temperature and high humidity environment, and can suppress defects of conduction when applied to an image display device.SOLUTION: A polarizing plate has: a polarizer; a first protective layer which is arranged on one side of the polarizer, and includes a resin film and a hard coat layer formed on a side opposite to the polarizer of the resin film; a second protective layer which is arranged on the other side of the polarizer; and an adhesive layer which is provided on a side opposite to the polarizer of the second protective layer. A total thickness of the polarizing plate is 70 μm or less, and the through hole is formed in the polarizing plate. A thickness of the polarizer is 12 μm or less; a thickness of the first protective layer is 29 μm or less and moisture permeability thereof is 200 g / m2 24h to 500 g / m2 24; moisture permeability of the second protective layer is less than 100 g / m2 24h; and a thickness of the adhesive layer is 12 μm to 17 μm and a surface resistance value thereof is 1.0×108 Ω / sq. to 2.0×109 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 polarizing plate. [Background technology]

[0002] Polarizing plates are widely used in image display devices such as mobile phones and notebook personal computers to enable image display and / or improve the performance of such image display. In recent years, with the rapid spread of smartphones and touch-panel information processing devices, image display devices equipped with cameras have become widely used. In response to this, polarizing plates with through-holes at positions corresponding to the camera section have also become widely used. Typically, the through-holes are filled with adhesive used for laminating the cover glass. Image display devices containing polarizing plates with through-holes filled with adhesive may experience the formation of air bubbles in the through-hole areas. Such air bubbles become more pronounced as the thickness of the adhesive filling the through-holes decreases. To suppress such air bubbles, attempts have been made to thin the polarizing plate (essentially, the through-holes). As one attempt at thinning, a technique has been proposed to omit the protective layer on the adhesive side of the polarizing plate. However, this technique has the problem of causing discoloration defects in high-temperature and high-humidity environments. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2017 / 047510 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a polarizing plate that is thin, has through holes, suppresses air bubbles when the through holes are filled with adhesive, has excellent reliability in high temperature and high humidity environments, and can suppress conductivity problems when applied to an image display device. [Means for solving the problem]

[0005] A polarizing plate according to an embodiment of the present invention comprises: a polarizer; a first protective layer disposed on one side of the polarizer and including a resin film and a hard coat layer formed on the side of the resin film opposite to the polarizer; a second protective layer disposed on the other side of the polarizer; and an adhesive layer provided on the side of the second protective layer opposite to the polarizer. The total thickness of the polarizing plate is 70 μm or less, and through holes are formed in the polarizing plate. The thickness of the polarizer is 12 μm or less; the thickness of the first protective layer is 29 μm or less, and the moisture permeability is 200 g / m². 2 24h~500g / m 2 • 24h; the moisture permeability of the second protective layer is 100g / m² 2 The adhesion period is less than 24 hours; the thickness of the adhesive layer is 12 μm to 17 μm; and the surface resistance is 1.0 × 10⁻⁶. 8 Ω / □~2.0×10 9 It is Ω / □. In one embodiment, the thickness of the hard coat layer is 5 μm or less. In one embodiment, the hard coat layer is a cured layer of a resin composition comprising a hexafunctional or more urethane acrylate, tricyclodecanedimethanol dimethacrylate, and a photopolymerization initiator. In one embodiment, the resin composition comprises the hexafunctional or more urethane acrylate and the tricyclodecanedimethanol dimethacrylate in a ratio of 60 / 40 (by weight) to 40 / 60 (by weight). In one embodiment, the resin film of the first protective layer is a triacetylcellulose film, and the second protective layer is composed of a cycloolefin resin film. In one embodiment, the diameter of the through hole is 5 mm or less. According to another aspect of the present invention, an image display device is provided. This image display device comprises: an image display cell; a polarizing plate bonded to the viewing side of the image display cell via the adhesive layer; and another adhesive layer disposed on the viewing side of the polarizing plate, wherein through holes in the polarizing plate are filled with the adhesive constituting the other adhesive layer. In one embodiment, the thickness of the other adhesive layer is 120 μm or less. In one embodiment, the image display device further includes a cover glass on the viewing side of the other adhesive layer. In one embodiment, the image display device has a camera unit at a position corresponding to the through-hole of the polarizing plate. [Effects of the Invention]

[0006] According to embodiments of the present invention, a polarizing plate can be realized that is thin, has through holes, suppresses air bubbles when the through holes are filled with adhesive, has excellent reliability in high temperature and high humidity environments (for example, small change in polarization degree, suppression of discoloration at the edges, small change in the surface resistance of the adhesive layer, and suppression of peeling from the image display cell), and can suppress conductivity problems when applied to an image display device. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of the main part of the polarizing plate near the through hole according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view of the main part of the polarizing plate near the through hole in an image display device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Note that the drawings are schematic representations for clarity, and the ratios of lengths, widths, thicknesses, angles, etc., shown in the drawings differ from actual dimensions.

[0009] A. Overall configuration of polarizing plates Figure 1 is a schematic cross-sectional view of the main part of the portion near the through hole in a polarizing plate according to one embodiment of the present invention. The polarizing plate 100 in the illustrated example has; a polarizer 10; a first protective layer 20 disposed on one side of the polarizer 10; a second protective layer 30 disposed on the other side of the polarizer 10; and an adhesive layer 40 provided on the side of the second protective layer 30 opposite to the polarizer 10. The first protective layer 20 includes a resin film 21 and a hard coat layer 22 formed on the side of the resin film 21 opposite to the polarizer 10. The adhesive layer 40 is used to bond the polarizing plate 100 to an image display cell. In practice, it is preferable that a separator (not shown) is temporarily attached to the surface of the adhesive layer 40 until the polarizing plate is put into use. By temporarily attaching the separator, the adhesive layer is protected and the polarizing plate can be rolled.

[0010] The polarizing plate 100 has through holes 50 formed therein. By forming through holes, for example, if the image display device incorporates a camera, adverse effects on the camera's performance can be prevented. Typically, the through holes are formed at or near the edge of the polarizing plate. With such a configuration, when the polarizing plate is applied to an image display device, the impact on image display can be minimized. Multiple through holes may be provided. Furthermore, the planar shape of the through holes can be any appropriate shape depending on the purpose. Specific examples of planar shapes include circles, ellipses, squares, rectangles, polygons (e.g., pentagons, hexagons, octagons) and combinations thereof (e.g., rectangles with arc-shaped long or short sides). The diameter of the through holes is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 5 mm or less. The lower limit of the diameter of the through holes may be, for example, 2 mm. According to embodiments of the present invention, even with such a small diameter of through holes, air bubbles can be effectively suppressed when filled with adhesive.

[0011] The total thickness of the polarizing plate is 70 μm or less, preferably 68 μm or less, more preferably 65 μm or less, and still more preferably 62 μm or less. By setting the total thickness of the polarizing plate to a predetermined value or less, it is possible to significantly suppress bubbles when the through holes are filled with an adhesive. In particular, even when the thickness of the adhesive (substantially, another adhesive layer described later) is thin, bubbles can be significantly suppressed. The lower limit of the total thickness of the polarizing plate can be, for example, 48 μm. In the present specification, the "total thickness of the polarizing plate" means the total thickness of the first protective layer, the polarizer, the second protective layer, and the adhesive layer.

[0012] The thickness of the polarizer is 12 μm or less, preferably 10 μm or less, more preferably 8 μm or less, still more preferably 6 μm or less, and particularly preferably 5 μm or less. The lower limit of the thickness of the polarizer may be, for example, 2 μm, or may be, for example, 1 μm. By setting the thickness of the polarizer within such a range, it becomes easy to achieve the above total thickness.

[0013] The thickness of the first protective layer is 29 μm or less, preferably 22 μm to 28 μm. By setting the thickness of the first protective layer within such a range, it becomes easy to achieve the above total thickness. Further, the moisture permeability of the first protective layer is 200 g / m 2 ·24h to 500 g / m 2 ·24h, preferably 220 g / m 2 ·24h to 480 g / m 2 ·24h, more preferably 300 g / m 2 ·24h to 450 g / m 2The humidity is 24 hours. If the humidity of the first protective layer is within this range, a polarizer with excellent reliability in high-temperature and high-humidity environments can be realized. More specifically, a polarizer with small changes in polarization degree in high-temperature and high-humidity environments can be realized (for example, a change of 0.02% or less in durability tests). If the humidity is too high, reliability in high-temperature and high-humidity environments may be insufficient. If a film with low humidity (for example, a cyclic olefin resin (COP) film) is used as the first protective layer, cracks may occur near the through-holes due to the difference in the coefficient of linear expansion with the polarizer in high-temperature environments (for example, in harsh high-temperature environments such as heat shock tests). The thickness and humidity of the first protective layer refer to the thickness and humidity of the laminate of the resin film and the hard coat layer, respectively.

[0014] The moisture permeability of the second protective layer is 100 g / m². 2 • Less than 24 hours, preferably 10 g / m² 2 • 24h~70g / m² 2 • 24 hours, more preferably 20 g / m² 2 • 24h~50g / m² 2 The humidity is 24 hours. If the humidity is too high, the stability of the surface resistance of the adhesive layer in a high-temperature, high-humidity environment may be insufficient (for example, the change in durability testing may exceed 10 times). As a result, when a polarizing plate is applied to an image display device, it may cause problems with the conductivity of the image display device.

[0015] The thickness of the adhesive layer is 12 μm to 17 μm, preferably 13 μm to 16 μm. If the thickness is too large, adhesive indentation (a phenomenon in which the adhesive layer indents) may occur during through-hole processing, resulting in a poor appearance, and / or, the total thickness of the polarizing plate may become too thick, causing air bubbles to form when filling the through-holes with adhesive (substantially, the adhesive that constitutes another adhesive layer described later). If the thickness is too small, the polarizing plate may peel off from the image display cell in a high-temperature, high-humidity environment. Furthermore, the surface resistance value of the adhesive layer is 1.0 × 10⁻⁶. 8 Ω / □~2.0×10 9 The ratio is Ω / □, preferably 3.0 × 10⁻⁶. 8Ω / □~1.2×10 9 Ω / □, more preferably 5.0 × 10 8 Ω / □~1.0×10 9 The ratio is Ω / □. If the surface resistance is too low, the touch sensitivity of the display may become excessive, causing malfunctions. If the surface resistance is too high, the conductivity of the film may be poor, and static electricity accumulated during the manufacturing process cannot be discharged, which may cause problems with image display.

[0016] The polarizer according to the embodiment of the present invention may be used as a viewing-side polarizer or as a back-side polarizer. Preferably, the polarizer according to the embodiment of the present invention can be used as a viewing-side polarizer. Furthermore, the polarizer according to the embodiment of the present invention may further have any suitable optical functional layer depending on the purpose. Examples of optical functional layers include a phase difference layer, a conductive layer for touch panels, and a reflective polarizer. The number, type, combination, and arrangement position of the optical functional layers can be appropriately set depending on the purpose.

[0017] The polarizer, first protective layer, second protective layer, and adhesive layer that constitute the polarizing plate will be described in detail below.

[0018] B. Polarizer A polarizer is typically composed of a resin film containing a dichroic substance. 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.

[0019] 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.

[0020] Specific examples of polarizers obtained using the above-mentioned laminate of two or more layers include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or polarizers 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 further include, if necessary, 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, the laminate is preferably 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. As a result, the optical properties of the polarizer obtained through processing steps in which the laminate is immersed in liquid, such as dyeing and water-based stretching, can be improved. 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 an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on 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.

[0021] The thickness of the polarizer is as described in section A above.

[0022] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is, for example, 41.5% to 44.0%, preferably 42.5% to 44.0%, and more preferably 43.0% to 44.0%. 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.

[0023] C. First protective layer C-1. Resin film As the resin film, any suitable resin film that can be used as a protective layer for a polarizer can be used as the first protective layer, as long as the desired moisture permeability described above is obtained. Specific examples of materials that make up the main component of the resin film include cellulosic resins such as triacetylcellulose (TAC). A film formed from such a resin can be combined with a specific hard coat layer described later to form a first protective layer of appropriate thickness with the desired moisture permeability described above.

[0024] The moisture permeability of the resin film is preferably 600 g / m². 2 24h~2000g / m 2 • 24 hours, more preferably 800 g / m² 2 24h~1500g / m 2The moisture permeability of the resin film is within this range. By combining it with a specific hard coat layer described later, a first protective layer having the desired moisture permeability can be formed.

[0025] The thickness of the resin film is preferably 15 μm to 28 μm, and more preferably 20 μm to 26 μm. As long as the thickness of the resin film is within this range, a first protective layer having the desired thickness can be formed.

[0026] C-2. Hard coat layer The hard coat layer preferably has excellent surface hardness (e.g., excellent pencil hardness, excellent steel wool scratch resistance), excellent mechanical strength, and excellent light transmittance. Any suitable configuration can be adopted for the hard coat layer as long as it has these desired properties. Typically, the hard coat layer is a cured layer of a resin composition containing a curable resin.

[0027] Specific examples of curable resins include thermosetting resins, UV-curable resins, electron beam-curable resins, and two-component mixed resins. UV-curable resins are preferred because they allow for easy operation and highly efficient formation of a hard coat layer. Specific examples of UV-curable resins include polyester resins, (meth)acrylic resins, urethane resins, amide resins, silicone resins, epoxy resins, and urethane (meth)acrylate resins. UV-curable resins include UV-curable monomers, oligomers, and polymers. The resin composition may contain, for example, a (meth)acrylic resin, or for example, a urethane (meth)acrylate resin, or a combination thereof. The hard coat layer may also contain, for example, a copolymer of a functional oligomer and a monomer. Examples of functional monomers include polyfunctional (meth)acrylates. (Meth)acrylates may be, for example, two-functional or more, or for example, three-functional or more. Examples of functional oligomers include curable urethane (meth)acrylates. The curable urethane (meth)acrylate is, for example, 6-functional or more, and for example, 8-functional to 10-functional. In one embodiment, the resin composition contains, for 100 parts by weight of curable resin, a total of preferably 60 parts by weight or more, more preferably 70 parts by weight or more, even more preferably 80 parts by weight or more, particularly preferably 90 parts by weight or more, and especially preferably 95 parts by weight or more, of curable urethane (meth)acrylate and polyfunctional (meth)acrylate. The total amount may be 100 parts by weight. The blending ratio of curable urethane (meth)acrylate and polyfunctional (meth)acrylate in the curable resin is preferably 60 / 40 (by weight) to 40 / 60 (by weight), and more preferably 55 / 45 (by weight) to 45 / 55 (by weight). In one embodiment, the curable resin is entirely composed of 6-functional or more urethane (meth)acrylate and polyfunctional (meth)acrylate. For example, the curable resin may consist of a decahedral urethane (meth)acrylate / tricyclodecane dimethanol dimethacrylate (50 / 50 by weight ratio).

[0028] The resin composition typically contains a photopolymerization initiator. Any suitable photopolymerization initiator is used depending on the type of curable resin.

[0029] The resin composition (and consequently the hard coat layer) may contain silicon as an element. Silicon may, for example, be a constituent element of a surface modifier. Therefore, the resin composition (and consequently the hard coat layer) may contain a surface modifier (typically a leveling agent), and the surface modifier may contain, for example, a silicon compound having a dimethylsiloxane skeleton. The silicon compound may be a dimethylsiloxane-modified methacrylate ester, a polydimethylsiloxane cyclic compound, or the like.

[0030] The pencil hardness of the hard coat layer is preferably F or higher, more preferably H or higher, and even more preferably 3H or higher. If the pencil hardness of the hard coat layer is within this range, sufficient protective function can be achieved as the outermost layer on the viewing side.

[0031] The moisture permeability per unit thickness of the hard coat layer is preferably 100 g / m². 2 24h·μm~400g / m² 2 ·24h·μm, more preferably 120g / m² 2 • 24h • μm ~ 250 g / m² 2 The moisture permeability is 24h·μm. If the moisture permeability of the hard coat layer is within this range, a first protective layer having the desired moisture permeability can be formed by combining it with the specific resin film mentioned above. The moisture permeability per unit thickness of the hard coat layer is the value obtained by subtracting the moisture permeability of the resin film from the moisture permeability of the first protective layer and dividing by the thickness of the hard coat layer.

[0032] The haze value of the hard coat layer may be, for example, 5% or more, 10% or more, 15% or more, or 20% or more. On the other hand, the haze value of the hard coat layer may be, for example, 50% or less, 45% or less, 40% or less, or 35% or less. If the haze value is within this range, the occurrence of grayscale and reflections from the outside can be suppressed, and the deterioration of the display characteristics of the image display device (e.g., clarity, contrast in dark places) can be suppressed. The haze value can typically be measured in accordance with JIS K 7136.

[0033] The thickness of the hard coat layer is preferably 5 μm or less, and more preferably 2 μm to 4 μm. Within this range, a first protective layer with the desired thickness can be formed while maintaining the desired moisture permeability.

[0034] The hard coat layer can be formed by any suitable method. For example, the hard coat layer can be formed by applying a hard coat layer-forming resin composition (coating liquid) onto a resin film, drying it, and curing the dried coating film by irradiating it with ultraviolet light.

[0035] D. Second protective layer The moisture permeability of the second protective layer is 100 g / m², as stated above. 2 • Less than 24 hours, preferably 10 g / m² 2 • 24h~70g / m² 2 • 24 hours, more preferably 20 g / m² 2 • 24h~50g / m² 2 The duration is 24 hours. If the moisture permeability of the second protective layer is within this range, the generation of air bubbles will be suppressed when the through-holes are filled with an adhesive (described later) that constitutes another adhesive layer, and the change in the surface resistance value of the adhesive layer in a high-temperature, high-humidity environment will be reduced.

[0036] The second protective layer may consist of any suitable resin film that can be used as a protective layer for the polarizer, provided that the desired moisture permeability is achieved. Specific examples of materials that make up the main component of the resin film include cycloolefin resins (e.g., norbornene resins).

[0037] The thickness of the second protective layer is preferably 10 μm to 30 μm, and more preferably 10 μm to 16 μm. As long as the thickness of the second protective layer is within this range, a polarizing plate having the above-mentioned desired properties and the above-mentioned desired total thickness can be formed.

[0038] E. Adhesive layer As described above, the adhesive layer is used to bond the polarizing plate to the image display cell. The surface resistance of the adhesive layer is 1.0 × 10⁻⁶, as described above. 8 Ω / □~2.0×10 9 The ratio is Ω / □, preferably 3.0 × 10⁻⁶. 8 Ω / □~1.2×10 9 Ω / □, more preferably 5.0 × 10 8 Ω / □~1.0×10 9 The ratio is Ω / □. If the surface resistance of the adhesive layer is within this range, conductivity problems can be suppressed when the polarizing plate is applied to an image display device.

[0039] The adhesive strength of the adhesive layer to the glass is preferably 1.5 N / 25 mm or more and less than 5.5 N / 25 mm, more preferably 2.5 N / 25 mm or more and 4.5 N / 25 mm or less, and even more preferably 3.0 N / 25 mm or more and 4.0 N / 25 mm or less. When the adhesive strength is within this range, it exhibits excellent adhesion to the image display panel and excellent reworkability.

[0040] The adhesive layer preferably has a storage modulus of 1.0 × 10⁻¹⁰ at 25°C. 4 Pa~1.0×10 6 Pa is more like 1.0 × 10⁻⁶. 4 Pa~1.0×10 5The storage modulus of the adhesive layer is within this range, which helps to suppress defects in the appearance of polarizing plates under high temperature and high humidity conditions. The storage modulus can be obtained by dynamic viscoelasticity measurement.

[0041] The creep amount ΔCr of the adhesive layer at 70°C is, for example, 120 μm or less, and may be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or even 15 μm or less. The lower limit of the creep amount ΔCr is, for example, 0.5 μm. If the creep amount is within this range, similar to the storage modulus, it is possible to suppress defects in the appearance of the polarizing plate in high temperature and high humidity environments. The creep value can be measured, for example, by the following procedure: A load of 500 gf is applied vertically downward to the adhesive layer attached to a stainless steel test plate with a joint surface of 20 mm vertically x 20 mm horizontally, while the test plate is fixed. The creep amount (slip amount) of the adhesive layer relative to the test plate is measured at 100 seconds and 3600 seconds after the start of load application, and the Cr is measured accordingly. 100 and Cr 3600 Let's assume that the measured Cr 100 and Cr 3600 Therefore, the equation ΔCr = Cr 3600 -Cr 100 The creep amount ΔCr can be determined by this.

[0042] The thickness of the adhesive layer is 12 μm to 17 μm, preferably 13 μm to 16 μm, as described above. If the thickness of the adhesive layer is within this range, peeling in high temperature and high humidity environments can be suppressed, and the generation of air bubbles can be suppressed when the through holes are filled with an adhesive that constitutes another adhesive layer (described later).

[0043] Any suitable adhesive can be used as the adhesive (adhesive composition) constituting the adhesive layer, as long as it satisfies the above-mentioned characteristics. Typically, the adhesive composition includes a base polymer and a conductive component.

[0044] 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.

[0045] (Meth)acrylic base polymers typically contain alkyl (meth)acrylate as the main monomer component. Examples of alkyl groups in alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9, more preferably 3 to 6. A preferred alkyl (meth)acrylate is butyl acrylate. The content of alkoxy group-containing monomers in the base polymer is preferably 50 parts by weight or more, more preferably 60 parts by weight or more, even more preferably 70 parts by weight or more, and particularly preferably 80 parts by weight or more, per 100 parts by weight of the total monomer components. Alkyl (meth)acrylate may be used alone or in combination of two or more types.

[0046] (Meth)acrylic base polymers typically contain monomer components (copolymerization monomer components) that can copolymerize with alkyl (meth)acrylates. Examples of copolymerization monomer components include carboxyl group-containing monomers, hydroxyl group-containing monomers, alkoxy group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic vinyl monomers. By appropriately adjusting the type, number, combination, and amount (content) of copolymerization monomers, a base polymer (and consequently, an adhesive layer) with desired properties can be obtained. In one embodiment, the (meth)acrylic base polymer may be a copolymer of alkyl (meth)acrylate (e.g., butyl acrylate), aromatic ring-containing (meth)acrylate (e.g., phenoxyethyl acrylate), heterocyclic vinyl monomer (e.g., N-vinyl-2-pyrrolidone), carboxyl group-containing monomer (e.g., acrylic acid), and hydroxyl group-containing monomer (e.g., 4-hydroxybutyl acrylate).

[0047] The weight-average molecular weight Mw of the (meth)acrylic-based polymer is preferably 1 million to 3 million, more preferably 1 million to 2 million, and even more preferably 1 million to 1.6 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.

[0048] Typical conductive components include inorganic cationic salts and organic cationic salts.

[0049] 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.

[0050] 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 from 1 to 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.

[0051] Examples of the fluorine-containing imide anion include imide anions having a perfluoroalkyl group. Specific examples include the above (CF3SO2)(CF3CO)N - and the general formulas (1), (2) and (4) (1): (C n F 2n+1 SO2)2N - (n is an integer from 1 to 10), (2): CF2(C m F 2m SO2)2N - (m 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), and the anions represented by. Preferably, it is a (perfluoroalkylsulfonyl)imide represented by the general formula (1) such as (CF3SO2)2N - , (C2F5SO2)2N - etc., and more preferably, it is bis(trifluoromethanesulfonyl)imide represented by (CF3SO2)2N - . Therefore, a preferred inorganic cation salt that can be used in the embodiments of the present invention is lithium bis(trifluoromethanesulfonyl)imide.

[0052] 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 organic oniums include tetraalkylammonium cations (e.g., trimethylbutylammonium 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 methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

[0053] Inorganic cation salts and organic cation salts may be used in combination.

[0054] The conductive component may be a solid or a liquid (i.e., an ionic liquid).

[0055] The content of the conductive component in the adhesive composition is preferably 5 to 15 parts by weight, and more preferably 8 to 12 parts by weight, per 100 parts by weight of the base polymer. Within this range of conductive component content, a desired surface resistance value can be obtained without adversely affecting other properties.

[0056] Adhesive compositions typically contain a silane coupling agent and / or a crosslinking agent. 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.

[0057] 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, anti-aging agents, 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.

[0058] F. Image display device A polarizing plate according to an embodiment of the present invention can be applied to an image display device. Therefore, an image display device is also included in the embodiments of the present invention. Examples of image display devices include liquid crystal displays, organic electroluminescent (EL) displays, and quantum dot displays. Figure 2 is a schematic cross-sectional view of the main part of the polarizing plate near the through-hole in an image display device according to one embodiment of the present invention. The illustrated image display device 200 has: an image display cell 120; a polarizing plate 100 bonded to the viewing side of the image display cell 120 via an adhesive layer 40; and another adhesive layer 140 disposed on the viewing side of the polarizing plate 100. The polarizing plate 100 is a polarizing plate according to an embodiment of the present invention described in sections A to E above. In the embodiment of the present invention, the through-hole 50 of the polarizing plate 100 is filled with an adhesive constituting the other adhesive layer 140. The illustrated image display device may further have a cover glass 160 on the viewing side of the other adhesive layer 140, if necessary. The cover glass 160 can be laminated onto the image display device (substantially, the polarizing plate 100) via another adhesive layer 140. In one embodiment, the image display device has a camera unit (not shown) at a position corresponding to the through-hole 50 of the polarizing plate 100. Such a configuration can prevent adverse effects on the camera's shooting performance. Regarding the configuration on the side opposite to the viewing side of the image display cell, any appropriate configuration can be adopted depending on the type of image display device, so a specific explanation is omitted.

[0059] Any suitable adhesive can be used as the adhesive constituting the other adhesive layer 140. Specific examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and blending ratio of monomers forming the base polymer of the adhesive, the amount of crosslinking agent, the type, number, combination and blending ratio of additives, the reaction temperature, and the reaction time, an adhesive with desired properties according to the purpose can be prepared. The base polymer of the adhesive may be used alone or in combination of two or more types. From the viewpoint of transparency, processability, and durability, acrylic adhesives are preferred.

[0060] Another adhesive layer has a storage modulus of elasticity before curing at 60°C, preferably 1.0 × 10⁻⁶. 3 Pa~1.0×10 6 Pa is more like 1.0 × 10⁻⁶. 4 Pa~1.0×10 5 The storage modulus at 25°C after curing of the other adhesive layer is preferably 1.0 × 10⁻⁶ Pa. 4 Pa~1.0×10 7 Pa is more like 1.0 × 10⁻⁶. 5 Pa~1.0×10 7 The storage modulus of the other adhesive layer is within this range. If the adhesive is soft when bonded and strong against external stress after curing, it can suppress air bubbles in the through-hole portion even with a thin thickness, as will be described later, due to the synergistic effect with the effects of the embodiment of the present invention.

[0061] The thickness of the other adhesive layer is preferably 150 μm or less, more preferably 120 μm or less, even more preferably 100 μm or less, and particularly preferably 75 μm or less. According to embodiments of the present invention, even with such a thin thickness of the other adhesive layer, it is possible to suppress air bubbles in the through-hole portions, and to realize a polarizing plate that is highly reliable in high-temperature and high-humidity environments and can suppress conductivity problems when applied to an image display device. The thickness of the other adhesive layer may be, for example, 50 μm or more. [Examples]

[0062] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are based on weight.

[0063] (1) Air bubbles in the through-hole The polarizing plates obtained in the examples and comparative examples were cut to 150 mm x 70 mm, and through holes with a diameter of 3 mm were formed so that the top of the through hole was located 3 mm from the top edge in the long side direction. These polarizing plates were bonded to a glass plate. A laminate with an optical adhesive (another adhesive layer, 100 μm thick, 3M "CEF7104") applied to the cover glass was bonded to the polarizing plate / glass plate laminate via the optical adhesive by vacuum lamination (pressure 0.3 MPa, temperature 60°C, 10 minutes), filling the through holes in the polarizing plates with the optical adhesive. Air bubbles in the through holes were observed visually and evaluated according to the following criteria. ○ (Good): No air bubbles were observed. × (Defective): Air bubbles were observed.

[0064] (2) Changes in polarization degree under high temperature and high humidity conditions The polarizing plates obtained in the examples and comparative examples were bonded to alkali-free glass plates to prepare the measurement samples. The polarization degree P0 of these measurement samples was measured using an ultraviolet-visible spectrophotometer (Otsuka Electronics LPF-200). Furthermore, these measurement samples were subjected to a 500-hour durability test at 65°C and 90%RH, and the polarization degree P0 after the test was measured. 500 The following was measured: ΔP = P0 - P 500 The following criteria were used to calculate and evaluate the results. ○ (Good): ΔP is less than 0.02% × (Defective): ΔP is 0.02% or higher

[0065] (3) Surface resistance of the adhesive layer and stability of the surface resistance The surface resistance of the adhesive layer of the polarizing plates obtained in the examples and comparative examples was measured using Hiresta UP MCP HT450 (Mitsubishi Chemical Analytech Co., Ltd.). Note that the surface resistance value was 2 × 10⁻⁶. 9 When the value exceeds Ω / □, conductivity problems often occur in image display devices; therefore, conductivity is judged to be good when it is below this value. Furthermore, the polarizing plate was subjected to a 500-hour durability test at 60°C and 90%RH, and the surface resistance value of the adhesive layer after the test was measured. The stability of the surface resistance value was evaluated according to the following criteria. ○ (Good): Surface resistance value is 2 × 10 9 Ω / □ or less × (Defective): Surface resistance value is 2 × 10 9 Ω / greater than □

[0066] (4) Delamination of polarizing plates in high temperature and high humidity environments The polarizing plates obtained in the examples and comparative examples were cut to 300 mm x 220 mm and bonded to alkali-free glass plates to be used as measurement samples. These measurement samples were subjected to a 500-hour durability test at 60°C and 90% RH, and the condition of the polarizing plates after the test was observed and evaluated according to the following criteria. ○ (Good): No peeling is observed, or peeling at the edges is less than 0.3 mm. × (Defective): Peeling of 0.3 mm or more was observed at the edges.

[0067] (5) Cracks near the through hole The polarizing plates obtained in the examples and comparative examples were cut to 150 mm x 70 mm, and through holes with a diameter of 3 mm were formed so that the top of the through hole was located 3 mm from the top edge in the long side direction. These polarizing plates were bonded to alkali-free glass plates and used as measurement samples. These measurement samples were subjected to a heat shock test in which the environment was changed between 85°C and -40°C for 200 cycles. After the test, cracks in the through-hole area were observed and evaluated according to the following criteria. ○ (Good): The maximum size of cracks near the through-hole is 300 μm or less. × (Defective): The maximum size of the crack near the through hole is greater than 300 μm.

[0068] <Manufacturing Example 1: Fabrication of Adhesive Layer> A monomer mixture containing 80.3 parts butyl acrylate, 16 parts phenoxyethyl acrylate, 3 parts N-vinyl-2-pyrrolidone (NVP), 0.3 parts acrylic acid, and 0.4 parts 4-hydroxybutyl acrylate 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 as a polymerization initiator to 100 parts of the monomer mixture (solids) together with 100 parts by weight of 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 around 55°C to prepare a solution of an acrylic polymer with a weight-average molecular weight (Mw) of 1.5 million. To 100 parts of the solid content of the obtained acrylic polymer solution, 8.5 parts of EMI-FSI (1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, an ionic liquid manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added as a conductive agent (antistatic agent). Furthermore, 0.2 parts of an isocyanate crosslinking agent (product name: Takenate D160N, trimethylolpropane hexamethylene diisocyanate, manufactured by Mitsui Chemicals, Inc.), 0.25 parts of benzoyl peroxide (product name: Naiper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.), 0.2 parts of a silane coupling agent (manufactured by Soken Chemical Co., Ltd.: A-100), and 0.3 parts of an antioxidant (product name: Irganox 1010, a hindered phenol, manufactured by BASF Japan) were added to obtain adhesive composition I.

[0069] Next, adhesive composition I was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Films, MHE38) treated with a silicone-based release agent, such that the thickness of the adhesive layer after drying was 15 μm. It was then dried at 155°C for 1 minute to form an adhesive layer A with a thickness of 15 μm on the surface of the separator film.

[0070] <Manufacturing Example 2: Fabrication of the Adhesive Layer> Except for changing the coating thickness of the adhesive composition I, an adhesive layer B with a thickness of 10 μm was formed on the surface of the separator film in the same manner as in Manufacturing Example 1.

[0071] <Manufacturing Example 3: Fabrication of the Adhesive Layer> Adhesive composition II was obtained in the same manner as in Production Example 1, except that 20 parts of TBMA-TFSI (tributylmethylammonium bis(trifluoromethane)sulfonimide, an ionic liquid manufactured by 3M, FC-4400) were used instead of 8.5 parts of EMI-FSI. An adhesive layer C with a thickness of 15 μm was formed on the surface of the separator film in the same manner as in Production Example 1, except that adhesive composition II was used.

[0072] <Manufacturing Example 4: Fabrication of the Adhesive Layer> Except for changing the coating thickness of the adhesive composition I, an adhesive layer D with a thickness of 20 μm was formed on the surface of the separator film in the same manner as in Manufacturing Example 1.

[0073] <Manufacturing Example 5: Fabrication of the Adhesive Layer> Adhesive composition III was obtained in the same manner as in Production Example 1, except that the amount of EMI-FSI was changed from 8.5 parts to 6.0 parts. An adhesive layer E with a thickness of 20 μm was formed on the surface of the separator film in the same manner as in Production Example 1, except that adhesive composition III was used and the coating thickness was changed.

[0074] <Manufacturing Example 6: Preparation of Resin Composition for Hard Coat Layer Formation> 50 parts by weight (based on solids content) of UV-curable acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-DCP", 100% solids content), 50 parts by weight (based on solids content) of UV-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, trade name "UV-1700TL", 80% solids content), 5 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), and 0.1 parts by weight of leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., trade name "LE-303", 40% solids content) were mixed. This mixture was diluted with a methyl isobutyl ketone (MIBK) / cyclopentanone mixed solvent (weight ratio 60 / 40) to a solids content of 30% to prepare hard coat layer forming resin composition (coating liquid) A. Note that "A-DCP" is tricyclodecanedimethanol dimethacrylate and "UV-1700TL" is a decaherophilic urethane acrylate. The hard coat layer formed from coating liquid A is referred to as hard coat layer A.

[0075] <Manufacturing Example 7: Preparation of Resin Composition for Hard Coat Layer Formation> 40 parts by weight of UV-curable acrylate resin (manufactured by Toagosei Co., Ltd., trade name "M-920", 100% solids), 60 parts by weight of UV-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, trade name "UV-1700TL", 80% solids), 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), and 0.2 parts by weight of leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., trade name "LE-303", 40% solids) were mixed. This mixture was diluted with MIBK / cyclopentanone mixed solvent (weight ratio 70 / 30) to a solids content of 30% to prepare hard coat layer forming resin composition (coating liquid) B. Note that "M-920" is glycerin triacrylate. The hard coat layer formed from coating liquid B is referred to as hard coat layer B.

[0076] <Manufacturing Example 8: Preparation of Resin Composition for Hard Coat Layer Formation> 100 parts by weight of UV-curable urethane acrylate (manufactured by DIC Corporation, trade name "Unidic 17-806", solids content 80%), 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD 907"), and 0.01 parts by weight of leveling agent (manufactured by DIC Corporation, trade name "PC4100", solids content 40%) were mixed. This mixture was diluted with a propylene glycol monomethyl ether (PGM) / cyclopentanone mixed solvent (weight ratio 63 / 37) to a solids content concentration of 36% to prepare hard coat layer forming resin composition (coating liquid) C. The hard coat layer formed from coating liquid C is referred to as hard coat layer C.

[0077] <Example 1> As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and 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") 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) 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 the desired 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% by weight, potassium iodide concentration 5% by weight) 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 material was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate / polarizer configuration was obtained.

[0078] A triacetylcellulose (TAC) film (25 μm thick) was prepared as the first protective layer resin film. Coating solution A from manufacturing example 6 was applied to this TAC film, and the coating film was heated at 60°C for 1 minute to dry. After that, it was exposed to a high-pressure mercury lamp with an integrated light intensity of 260 mJ / cm². 2 The above coating film was cured by irradiation with ultraviolet light to form a hard coat (HC) layer A with a thickness of 3 μm. In this way, an HC-TAC film was obtained as the first protective layer. The HC-TAC film was laminated as the first protective layer to the polarizer surface (the side opposite to the resin substrate) of the laminate obtained above. The HC-TAC film was laminated so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off, and a cyclic olefin resin (COP) film (thickness 13 μm) was laminated to the peeled surface as the second protective layer. Furthermore, the adhesive layer A (thickness 15 μm) from Production Example 1 was transferred to the surface of the COP film. In this way, a polarizing plate having the configuration of first protective layer (HC layer A / TAC film) / polarizer (5 μm) / second protective layer (COP film) / adhesive layer A was obtained. The obtained polarizing plate was subjected to the evaluations of (1) to (5) above. The results are shown in Table 1.

[0079] <Example 2> A long polyvinyl alcohol (PVA) resin film was infused with iodine and uniaxially stretched in the longitudinal direction (MD direction) to produce a polarizer (thickness 12 μm). A polarizing plate with through holes was obtained in the same manner as in Example 1, except that this polarizer was used. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0080] <Comparative Examples 1-9> A polarizing plate with the configuration shown in Table 1 was fabricated. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0081] [Table 1]

[0082] In Table 1, the unit for thickness is "μm", and the unit for moisture permeability is "g / m". 2 It's "24 hours".

[0083] As is clear from Table 1, the polarizing plates of the embodiments of the present invention are thin, have suppressed air bubbles in the through-hole portions, and exhibit excellent reliability in high-temperature and high-humidity environments (specifically, the change in polarization degree is small, the change in the surface resistance of the adhesive layer is small, and peeling from the image display cell is suppressed). Furthermore, the polarizing plates of the embodiments of the present invention can be seen from the surface resistance of the adhesive layer to suppress conductivity problems when applied to image display devices. [Industrial applicability]

[0084] The polarizing plate according to the embodiment of the present invention is suitably used in image display devices, and in particular suitably used in image display devices having a camera unit, such as smartphones, tablet PCs, or smartwatches. [Explanation of symbols]

[0085] 10 Polarizers 20. First protective layer 21 Resin film 22 Hard court layer 30. Second protective layer 40 Adhesive layer 50 Through holes 100 polarizing plates 120 Image Display Cells 140 Another adhesive layer 200 Image Display Devices

Claims

1. A polarizer; a first protective layer disposed on one side of the polarizer and comprising a resin film and a hard coat layer formed on the side of the resin film opposite to the polarizer; a second protective layer disposed on the other side of the polarizer; and an adhesive layer provided on the side of the second protective layer opposite to the polarizer; The total thickness is 70 μm or less. A through hole is formed, The thickness of the polarizer is 12 μm or less. The thickness of the first protective layer is 29 μm or less, and the moisture permeability is 200 g / m². ２ ・24h~500g / m ２ ・It is 24 hours, The moisture permeability of the second protective layer is 100 g / m². ２ - Less than 24 hours, The thickness of the adhesive layer is 12 μm to 17 μm, and the surface resistance value is 1.0 × 10⁻⁶. ８ Ω / □ ~ 2.0 × 10 ９ Ω / □, The hard coat layer is a cured layer of a resin composition containing a curable resin, The curable resin contains a hexafunctional or more curable urethane (meth)acrylate and a polyfunctional (meth)acrylate in a ratio of 55 / 45 (by weight) to 45 / 55 (by weight). Polarizing plate.

2. The polarizing plate according to claim 1, wherein the thickness of the hard coat layer is 5 μm or less.

3. The polarizing plate according to claim 2, wherein the hard coat layer is a cured layer of a resin composition containing a hexafunctional or more urethane acrylate, tricyclodecanedimethanol dimethacrylate, and a photopolymerization initiator.

4. The polarizing plate according to any one of claims 1 to 3, wherein the resin film of the first protective layer is a triacetylcellulose film and the second protective layer is composed of a cycloolefin resin film.

5. The polarizing plate according to any one of claims 1 to 4, wherein the diameter of the through hole is 5 mm or less.

6. The device comprises: an image display cell; a polarizing plate according to any one of claims 1 to 5, which is bonded to the viewing side of the image display cell via the adhesive layer; and another adhesive layer disposed on the viewing side of the polarizing plate. The through-holes of the polarizing plate are filled with the adhesive that constitutes the other adhesive layer. Image display device.

7. The image display device according to claim 6, wherein the thickness of the other adhesive layer is 120 μm or less.

8. The image display device according to claim 6 or 7, further comprising a cover glass on the visible side of the other adhesive layer.

9. The image display device according to any one of claims 6 to 8, further comprising a camera unit positioned at a location corresponding to the through-hole of the polarizing plate.

Images