Polarizing plate, polarizing plate with cover glass, and image display device

Abstract

To provide a polarizing plate with a smaller deviation at a through hole part even under a high temperature environment, the polarizing plate capable of significantly suppressing air bubbles at the through hole part when a through hole is filled by an adhesive agent for laminating cover glass in a picture display unit.SOLUTION: A polarizing plate includes a polarizer, a protective layer arranged at least on one side of the polarizer, and an adhesive layer, and further includes a through hole formed therein. The polarizer has a thickness of 15 μm or less and |b1-b2| of 45 mm or less. b1 is a distance from a center of the through hole to one end of the polarizing plate in an absorption axis direction of the polarizer, and b2 is a distance from the center of the through hole to the other end of the polarizing plate in the absorption axis direction of the polarizer.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to polarizing plates and image display devices. More specifically, the present invention relates to polarizing plates having an adhesive layer and having through holes formed therein, and to image display devices including such polarizing plates. [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, the use of polarizing plates has also been desired in image display devices equipped with cameras, smartwatches, and automotive instrument panels, and through holes are sometimes formed in polarizing plates. However, polarizing plates with through holes have a problem in which displacement of the polarizing plate (essentially displacement of the adhesive layer) occurs at the through-hole portion in high-temperature environments.

[0003] Incidentally, in order to impart surface hardness and impact resistance to image display devices, a cover glass is sometimes laminated onto the outermost surface of the image display device. When a cover glass is laminated onto an image display device that includes a polarizing plate with through holes, the through holes are typically filled with an adhesive for laminating the cover glass. However, in image display devices where the through holes are filled with adhesive, air bubbles may form in the filled areas (through-hole areas) due to heat treatment or other processes during the manufacturing process. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2017 / 047510 [Patent Document 2] Japanese Patent Publication No. 2016-094569 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a polarizing plate in which displacement in the through-hole portion is small even in high-temperature environments, and in which air bubbles in the through-hole portion can be significantly suppressed when the through-hole is filled with an adhesive for laminating cover glass in an image display device. [Means for solving the problem]

[0006] The polarizing plate of the present invention comprises a polarizer, a protective layer disposed on at least one side of the polarizer, and an adhesive layer, with through holes formed therein, the thickness of the polarizer being 15 μm or less, and |b1-b2| being 45 mm or less. Here, b1 is the distance from the center of the through hole to one end of the polarizing plate in the absorption axis direction of the polarizer, and b2 is the distance from the center of the through hole to the other end of the polarizing plate in the absorption axis direction of the polarizer. In one embodiment, the polarizer has a rectangular shape, and when viewed from the viewing side, the absorption axis direction of the polarizer is 135° clockwise from the direction of the long side, and the through hole is formed in the right corner. In another embodiment, the polarizer has a rectangular shape, and when viewed from the viewing side, the absorption axis direction of the polarizer is 45° clockwise from the direction of the long side, and the through hole is formed in the left corner. In yet another embodiment, the polarizer has a rectangular shape, the absorption axis direction of the polarizer is in the direction of the short side, and when viewed from above, the through hole is formed at the end in the direction of the long side and in the center in the direction of the short side. In one embodiment, the thickness of the polarizer is 8 μm or less. In one embodiment, the creep value of the adhesive layer is 140 μm / hr or less. According to another aspect of the present invention, an image display device is provided. This image display device includes an image display cell and the polarizing plate, wherein the polarizing plate is bonded to the image display cell via the adhesive layer. [Effects of the Invention]

[0007] According to an embodiment of the present invention, a polarizing plate having through-holes can be realized, in which the deviation in the through-hole portion is small even in a high-temperature environment, and the bubbles in the through-hole portion can be significantly suppressed when the through-holes are filled with an adhesive for laminating a cover glass in an image display device.

Brief Description of Drawings

[0008] [Figure 1A] It is a schematic plan view for explaining the formation position of through-holes in a polarizing plate according to one embodiment of the present invention. [Figure 1B] It is a schematic plan view for explaining the formation position of through-holes in a polarizing plate according to another embodiment of the present invention. [Figure 1C] It is a schematic plan view for explaining the formation position of through-holes in a polarizing plate according to still another embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view of a through-hole portion of a polarizing plate according to an embodiment of the present invention. [Figure 3] It is an enlarged cross-sectional view of a main part for explaining the deviation in the through-hole portion in a polarizing plate according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. For clarity, the drawings are schematically shown, and further, the ratios of lengths, widths, thicknesses, etc., and angles, etc. in the drawings are different from the actual ones.

[0010] A. Overall Configuration of Polarizing Plate Figure 1A is a schematic plan view illustrating the formation location of through-holes in a polarizing plate according to one embodiment of the present invention; Figure 1B is a schematic plan view illustrating the formation location of through-holes in a polarizing plate according to another embodiment of the present invention; Figure 1C is a schematic plan view illustrating the formation location of through-holes in a polarizing plate according to yet another embodiment of the present invention; Figure 2 is a schematic cross-sectional view of the through-hole portion of the polarizing plate. A polarizing plate according to an embodiment of the present invention (polarizing plates 100, 101, and 102 in the illustrated example) includes a polarizer 11, a protective layer (hereinafter sometimes referred to as the outer protective layer) 12 disposed on one side of the polarizer 11, a protective layer (hereinafter sometimes referred to as the inner protective layer) 13 disposed on the other side of the polarizer 11, and an adhesive layer 20. The adhesive layer 20 is used to bond the polarizing plate 100 to an image display cell. Depending on the purpose and desired configuration, either the outer protective layer 12 or the inner protective layer 13 may be omitted.

[0011] The polarizing plate has through holes 30 formed therein. By forming through holes, it is possible to prevent adverse effects on the performance of the camera, for example, when an image display device incorporates a camera. The through holes can be formed by various methods, such as laser processing, cutting with an end mill, or punching with a Thomson blade or Pinnacle® blade. The polarizing plate typically has a rectangular shape. In this specification, when we refer to a "rectangular shape," we also include shapes that include irregularly shaped parts, such as R-shaped parts with chamfered edges, as shown in Figures 1A to 1C. Multiple through holes may be provided, although they are not shown. In addition, 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, and combinations thereof (for example, rectangles with arc-shaped edges), as shown in the illustrated example. Furthermore, irregularly shaped parts (for example, U-shaped notches, V-shaped notches) may be provided along with the through holes. The inventors of the present invention have discovered a new problem: when through-holes are formed in a polarizing plate, under high-temperature environments, displacement of the polarizing plate (substantially, displacement of the adhesive layer; hereinafter sometimes referred to as adhesive displacement) occurs in the through-hole portion, and as a result, there is a risk of light leakage occurring in the through-hole portion. The inventors of the present invention have solved this problem by adopting a predetermined configuration (described later) of the embodiment of the present invention. In other words, the present invention solves a previously unknown new problem, and the effect obtained therefrom is unexpectedly excellent. Furthermore, the inventors of the present invention have found that by adopting a predetermined configuration (described later) of the embodiment of the present invention, bubbles, also known as delay bubbles, can be significantly suppressed. Details of delay bubbles are as follows. In order to impart surface hardness and impact resistance to an image display device, a cover glass may be laminated on the outermost surface of the image display device. When a cover glass is laminated to an image display device including a polarizing plate having through-holes, the through-holes are typically filled with an adhesive for laminating the cover glass. Such filling is typically performed by attaching a laminate of cover glass and an adhesive sheet to the polarizing plate by vacuum lamination.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 due to the shrinkage stress of the polarizing plate 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. This is unacceptable both from an aesthetic standpoint and from the perspective of camera performance of the camera unit located at the position corresponding to the through-hole. Therefore, suppressing delay bubbles can significantly improve the commercial value of the image display device.

[0012] In embodiments of the present invention, the thickness of the polarizer is 15 μm or less, preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less, particularly preferably 6 μm or less, and especially preferably 5 μm or less. The thickness of the polarizer may be, for example, 1 μm or more, or for example, 2 μm or more. By setting the thickness of the polarizer within this range, thermal shrinkage of the polarizer itself can be suppressed. As a result, deformation of the adhesive layer (resulting in adhesive slippage) that can follow the thermal shrinkage of the polarizer can be suppressed.

[0013] Furthermore, in embodiments of the present invention, |b1-b2| is 45 mm or less, preferably 30 mm or less, more preferably 20 mm or less, even more preferably 10 mm or less, and particularly preferably 5 mm or less. The smaller |b1-b2| is, the better, and most preferably it is 0 (zero). If |b1-b2| is within this range, adhesive slippage in the through-hole portion under high-temperature environments can be reduced, and delay bubbles can be suppressed. On the other hand, |a1-a2| does not substantially contribute to suppressing adhesive slippage or delay bubbles in the through-hole portion. That is, changing |a1-a2| does not suppress adhesive slippage or delay bubbles. Here, b1 is the distance from the center of the through-hole to one end of the polarizer plate in the direction of the polarizer's absorption axis, b2 is the distance from the center of the through-hole to the other end of the polarizer plate in the direction of the polarizer's absorption axis, a1 is the distance from the center of the through-hole to one end of the polarizer plate in a direction perpendicular to the polarizer's absorption axis, and a2 is the distance from the center of the through-hole to the other end of the polarizer plate in a direction perpendicular to the polarizer's absorption axis. In other words, by optimizing the orientation of the polarizer's absorption axis with respect to the position of the through-hole, both glue slippage and delay bubbles can be suppressed.

[0014] Referring to Figures 1A to 1C, the relationship between a1, a2, b1, and b2 and the formation position of the through-hole will be explained in detail. Figure 1A shows a configuration in which the polarizing plate is rectangular, and when viewed from the viewing side of the image display device (opposite the adhesive layer), the absorption axis direction A of the polarizer is 135° clockwise with respect to the direction of the long side. In this configuration, by optimizing |b1-b2|, the through-hole 30 can be formed at any position on a straight line extending perpendicular to the absorption axis direction A from the upper right corner when the polarizing plate is viewed from the viewing side (on the straight line showing distances a1 and a2 in Figure 1A), thereby suppressing both adhesive slippage and delay bubbles. On the other hand, by adjusting |a1-a2| to minimize the impact on image display, the through-hole 30 can preferably be formed in the upper right corner. Figure 1B shows a configuration in which the polarizing plate is rectangular, and when viewed from the viewing side of the image display device, the absorption axis direction A of the polarizer is 45° clockwise with respect to the direction of the long side. In this configuration as well, by optimizing |b1-b2|, both adhesive slippage and delay bubbles can be suppressed, and by adjusting |a1-a2|, the impact on image display can be minimized. As a result, in this configuration, the through-hole 30 can preferably be formed in the upper left corner. Figure 1C shows a configuration in which the polarizing plate is rectangular and the absorption axis direction A of the polarizer is in the direction of the short side (perpendicular to the direction of the long side). In this configuration as well, by optimizing |b1-b2|, both adhesive slippage and delay bubbles can be suppressed, and by adjusting |a1-a2|, the impact on image display can be minimized. As a result, in this configuration, the through-hole 30 can preferably be formed at the end in the direction of the long side and in the center in the direction of the short side. As is clear from the above, according to the embodiments of the present invention, regardless of the planar shape of the polarizing plate (for example, even if it has a special planar shape), by optimizing |b1-b2|, the relationship between the position of the through-hole and the absorption axis direction in which adhesive slippage and delay bubbles can be suppressed can be determined. Furthermore, by adjusting |a1-a2|, the impact of the through-hole on image display can be minimized.

[0015] In one embodiment, as shown in Figure 3, the polarizing plate 100 is subjected to a heating test at 85°C for 120 hours with the polarizing plate 100 bonded to a glass plate (which may correspond to the substrate of an image display cell) 120 via an adhesive layer 20. The amount of displacement (adhesive displacement) D in the through-hole 30 portion is preferably 150 μm or less, more preferably 120 μm or less, even more preferably 100 μm or less, particularly preferably 80 μm or less, and especially preferably 50 μm or less. The smaller the displacement D, the better. The lower limit of the adhesive displacement D can be, for example, 10 μm or 20 μm. Note that the adhesive displacement D refers to the maximum portion of the polarizing plate that is farther from the through-hole portion when viewed in cross-section. The reference point for the through-hole portion can typically be the lower end of the adhesive layer. In other words, when the polarizing plate shifts (to the right in the illustrated example) mainly due to the contraction of the polarizer 11, the adhesive layer 20 remains attached to the glass plate 120, and the shift is recognized in the through-hole portion. As shown in Figure 3, the polarizing plate typically shifts away from the through-hole portion (right side of Figure 3), while the opposite portion shifts so as to protrude into the through-hole (left side of Figure 3). As described above, according to the embodiment of the present invention, the newly discovered problem of adhesive shift in the through-hole portion under high-temperature conditions can be solved, and specifically, the amount of adhesive shift D after a predetermined heating test can be set to the range described above.

[0016] In one embodiment, the polarizing plate may have an adhesive void formed in the through-hole 30 portion, where the end face of the adhesive layer 20 is located inward in the plane direction from the end face of the polarizing plate (substantially, the polarizer 11 or, if present, the inner protective layer 13). The size of the adhesive void is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, particularly preferably 100 μm or less, and especially preferably 80 μm or less. The lower limit of the size of the adhesive void may be, for example, 10 μm. In this specification, "size of the adhesive void" means the maximum length from the end face of the polarizing plate (substantially, the polarizer 11 or, if present, the inner protective layer 13) to the end face of the adhesive layer 20.

[0017] In embodiments of the present invention, the dimensional shrinkage rate of the polarizing plate after the above heating test is preferably 1.0% or less, more preferably 0.6% or less, and even more preferably 0.3% or less. The smaller the dimensional shrinkage rate, the better, and the lower limit of the dimensional shrinkage rate may be, for example, 0.01%. The dimensional shrinkage rate is calculated using the following formula. The dimensional shrinkage rate is the dimensional shrinkage rate of the entire polarizing plate attached to the glass plate, and if the polarizing plate further has an optical functional layer (e.g., a phase difference layer, a reflective polarizer) as described later, it means the dimensional shrinkage rate of the entire polarizing plate including the optical functional layer. In the following formula, "dimension" refers to the dimension of the polarizing plate (substantially, the polarizer) in the direction of the absorption axis. Dimensional shrinkage rate (%) = {(Dimensions before heating test - Dimensions after heating test) / Dimensions before heating test} × 100

[0018] The diameter R of the through-hole 30 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-hole may be, for example, 1.5 mm, or for example, 2 mm. The ratio of the amount of adhesive slippage D to the diameter R of the through-hole, D / R, is preferably 15% or less, more preferably 10% or less, even more preferably 6% or less, and particularly preferably 5% or less. On the other hand, the smaller the lower limit of D / R, the better. According to the embodiment of the present invention, since the amount of adhesive slippage D is very small as described above, D / R can be kept within this range even if the diameter of the through-hole is reduced. Therefore, even if the diameter of the through-hole is reduced, adverse effects on camera performance can be substantially prevented. As a result, the polarizing plate according to the embodiment of the present invention can be applied to an image display device and / or a bezel-less image display device in which only the camera portion is a non-display area.

[0019] The polarizer according to the embodiment of the present invention may be used as a viewing-side polarizer or as a back-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.

[0020] In one embodiment, a phase difference layer may be provided between the inner protective layer 13 and the adhesive layer 20. The phase difference layer may consist of a single layer or have a laminated structure. When the phase difference layer consists of a single layer, it can typically function as a λ / 4 plate. In this case, the in-plane phase difference Re(550) of the phase difference layer is preferably 100 nm to 200 nm, more preferably 120 nm to 170 nm, and even more preferably 130 nm to 150 nm. The angle between the absorption axis of the polarizer and the slow axis of the phase difference layer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 46°. The phase difference layer preferably exhibits inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measured light. In this case, the Re(450) / Re(550) of the phase difference layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. The phase difference layer may be a stretched resin film or an oriented solidified layer of a liquid crystal compound. When the phase difference layer is composed of a resin film, it may also serve as an inner protective layer. For example, a phase difference layer composed of a stretched resin film is described in Japanese Patent Publication No. 2017-54093 and Japanese Patent Publication No. 2018-60014. Specific examples of liquid crystal compounds and details of the method for forming the oriented solidified layer are described in Japanese Patent Publication No. 2006-163343. The descriptions in these publications are incorporated herein by reference. In this specification, "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d, where d(nm) is the thickness of the layer (film). nx is the refractive index in the direction where the refractive index is maximum in the plane (i.e., in the direction of the slow phase axis), and ny is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., in the direction of the fast phase axis).

[0021] When the phase difference layer has a laminated structure, the phase difference layer typically has an H layer and a Q layer in that order from the polarizer side. The H layer can typically function as a λ / 2 plate, and the Q layer can typically function as a λ / 4 plate. The Re(550) of the H layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 260 nm to 280 nm. The angle between the absorption axis of the polarizer and the slow axis of the H layer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 14° to 16°. The Re(550) of the Q layer is preferably 100 nm to 200 nm, more preferably 120 nm to 170 nm, and even more preferably 130 nm to 150 nm. The angle between the absorption axis of the polarizer and the slow axis of the Q layer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 74° to 76°. The arrangement order of the H layer and the Q layer may be reversed, and the angle between the slow axis of the H layer and the absorption axis of the polarizer, and the angle between the slow axis of the Q layer and the absorption axis of the polarizer, may also be reversed. The H layer and the Q layer may be stretched resin films or oriented solidified layers of liquid crystal compounds, respectively.

[0022] In one embodiment, a conductive layer for a touch panel may be provided on the side of the inner protective layer 13 (or phase difference layer, if present) opposite the polarizer. With such a configuration, the polarizer can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between the image display cell and the polarizer. The polarizer in this embodiment is typically a viewing-side polarizer.

[0023] In one embodiment, a reflective polarizer may be provided on the side of the outer protective layer 12 opposite to the polarizer. The reflective polarizer may also serve as the outer protective layer. The polarizer in this embodiment is typically a back-side polarizer. Details of the reflective polarizer are described, for example, in Japanese Patent Publication No. 9-507308 and Japanese Patent Application Publication No. 2013-235259. The descriptions in these publications are incorporated herein by reference.

[0024] In the embodiment of the present invention, the polarizing plate, when rectangular, preferably has an aspect ratio of 1.3 to 2.5. In this case, the size of the polarizing plate is, for example, 145 mm to 155 mm in height and 65 mm to 75 mm in width, or 230 mm to 240 mm in height and 140 mm to 150 mm in width. That is, the polarizing plate according to the embodiment of the present invention can be suitably used in smartphones or tablet PCs. For example, the size of the smartphone may be 120 mm to 200 mm in height and 30 mm to 120 mm in width.

[0025] The polarizer, protective layer, and adhesive layer that make up the polarizing plate will be described in detail below.

[0026] B. Polarizing plate B-1.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.

[0027] 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 resin 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 resin film, but also swell the PVA-based resin film to prevent uneven dyeing.

[0028] 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, 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. 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 a polarizer manufacturing method are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The descriptions in these patent documents are incorporated herein by reference.

[0029] The thickness of the polarizer is as described in section A above.

[0030] 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 46.0%, preferably 43.0% to 46.0%, and 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.

[0031] B-2.Protective layer The protective layer 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 can also be used. 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.

[0032] The outer protective layer 12 (especially when the polarizer is a viewing-side polarizer) may be subjected to surface treatments such as hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating, as needed. Furthermore / or, the outer protective layer 12 may be subjected to treatments to improve visibility when viewed through polarized sunglasses (typically, by providing (elliptic) circular polarization function or providing ultra-high phase difference), as needed. By applying such treatments, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses. Therefore, the polarizer can be suitably applied to image display devices that may be used outdoors.

[0033] The inner protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm. Here, "Rth(λ)" is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) can be calculated by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). nz is the refractive index in the thickness direction.

[0034] The thickness of the protective layer can be any appropriate thickness. For example, the thickness of the protective layer is 10 μm to 50 μm, preferably 20 μm to 40 μm. If a surface treatment is applied, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0035] C.Adhesive layer The adhesive layer 20 is used to bond the polarizing plate to the image display cell, as described above. The adhesive layer can typically be composed of an acrylic adhesive (acrylic adhesive composition). The acrylic adhesive composition typically contains a (meth)acrylic polymer as its main component. The (meth)acrylic polymer may be contained in the adhesive composition in a proportion of, for example, 50% or more by weight, preferably 70% or more by weight, and more preferably 90% or more by weight, of the solid content of the adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as its main component as a monomer unit. Note that (meth)acrylate refers to acrylate and / or methacrylate. The alkyl (meth)acrylate may be contained in a proportion of, for example, 80% or more by weight, and more preferably 90% or more by weight, of the monomer components forming the (meth)acrylic polymer. 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. Examples of monomers (copolymer monomers) constituting the (meth)acrylic polymer include, in addition to alkyl (meth)acrylate, carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, heterocyclic vinyl monomers, and the like. Representative examples of copolymer monomers include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic adhesive composition may preferably contain a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include epoxy group-containing silane coupling agents. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Furthermore, the acrylic adhesive composition may contain an antioxidant and / or a conductive agent. The thickness of the adhesive layer is, for example, 50 μm or less, and more preferably 22 μm or less, and more preferably 10 μm to 22 μm, as described above.Details of the adhesive layer or the acrylic adhesive composition are described in, for example, JP-A-2006-183022, JP-A-2015-199942, JP-A-2018-053114, JP-A-2016-190996, and WO 2018 / 008712, and the descriptions in these publications are incorporated herein by reference.

[0036] The creep value of the adhesive layer is preferably 140 μm / hr or less, more preferably 100 μm / hr or less, still more preferably 75 μm / hr or less, and particularly preferably 50 μm / hr or less. The lower limit of the creep value can be, for example, 20 μm / hr. In the present specification, the "creep value" means the creep value at 85°C. The creep value can be measured, for example, by the following procedure: The adhesive constituting the adhesive layer is adhered to a support plate. With the support plate to which the adhesive is attached fixed, a 500 g load is applied vertically downward. The amount of displacement of the adhesive from the support plate 1 hour after the load is applied is measured, and this displacement amount is taken as the creep value (μm / hr).

[0037] The storage elastic modulus G2' of the adhesive layer at -40°C is preferably 1.0×10 5 (Pa) or more, more preferably 1.0×10 6 (Pa) or more, still more preferably 1.0×10 7 (Pa) or more, and particularly preferably 1.0×10 8 (Pa) or more. The storage elastic modulus G2' can be, for example, 1.0×10 9 (Pa) or less. The storage elastic modulus G3' of the adhesive layer at 85°C is preferably 1.0×10 5 (Pa) or more, more preferably 3.0×10 5 (Pa) or more, still more preferably 5.0×10 5 (Pa) or more. The storage elastic modulus G3' can be, for example, 1.0×10 6 (Pa) or less.

[0038] D. 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. An image display device includes an image display cell and a polarizing plate. The polarizing plate is a polarizing plate according to the embodiments of the present invention described in sections A to C above. The polarizing plate is bonded to the image display cell via an adhesive layer. Examples of image display devices include liquid crystal displays, organic electroluminescent (EL) displays, and quantum dot displays.

[0039] E. Polarizing plate with cover glass When a polarizing plate according to an embodiment of the present invention is applied to the viewing side of an image display device, a cover glass may be bonded to the polarizing plate via another adhesive layer (hereinafter sometimes referred to as a second adhesive layer). Therefore, embodiments of the present invention include polarizing plates with a cover glass layer. Alternatively, a polarizing plate according to an embodiment of the present invention may be provided in a form with a separator temporarily attached instead of a cover glass. In this case, the separator is peeled off when manufacturing the image display device, and the cover glass is bonded via the exposed second adhesive layer. In either case, through holes can typically be filled with the adhesive constituting the second adhesive layer. The adhesive constituting the second adhesive layer will be described below.

[0040] The adhesive constituting the second adhesive layer has a storage modulus at 60°C of 1.0 × 10 when the second adhesive layer is laminated onto the polarizing plate. 4 Pa~1.0×10 5The storage modulus is Pa. Any suitable adhesive can be used for the second adhesive layer, as long as it has such a storage modulus at the time of lamination. Specifically, the adhesive may be a photocurable adhesive or a noncurable adhesive. In this specification, "photocurable adhesive" refers to an adhesive in which a crosslinking reaction proceeds upon irradiation with light. Therefore, a photocurable adhesive is soft and highly deformable at the time of lamination, and after lamination, it can be given desired properties (e.g., storage modulus) as an adhesive layer by irradiation with light. As a result, the photocurable adhesive has excellent filling properties for irregularly shaped processed parts, and the thickness of the second adhesive layer (and consequently the image display device) can be reduced. Furthermore, even if a thick frame printing layer is formed on the cover glass, for example, good adhesion can be ensured. "Noncurable adhesive" refers to an adhesive in which the crosslinking reaction is substantially completed and the crosslinking reaction does not substantially proceed after lamination. In other words, a noncurable adhesive may be a so-called ordinary adhesive. Non-curing adhesives offer superior productivity because they do not require light curing, and they also prevent issues such as dents, adhesive overflow from the edges of die-cut products, and handling problems.

[0041] The storage modulus of the photocurable adhesive at 60°C before curing can substantially correspond to the storage modulus during lamination as described above. The storage modulus before curing is 1.0 × 10⁻⁶ as described above. 5 It is less than or equal to Pa, preferably 1.0 × 10⁻⁶ 3 Pa~1.0×10 5 The storage modulus of the photocurable adhesive at 60°C after curing is preferably 5.0 × 10⁻⁶. 3 Pa~5.0×10 5 The pressure is Pa. The gel fraction of the photocurable adhesive before curing is 0% to 60%, and the gel fraction after curing is 50% to 95%. When the second adhesive layer is composed of a photocurable adhesive, the thickness of the second adhesive layer is preferably 50 μm to 500 μm, more preferably 75 μm to 475 μm, and even more preferably 100 μm to 450 μm.

[0042] The storage modulus at 60°C when the non-curing adhesive is laminated is preferably 1.0 × 10⁻⁶. 3 Pa~8.0×10 4 Pa is more like 5.0 × 10 3 Pa~6.0×10 4 The pressure is Pa. When the second adhesive layer is composed of a non-curing adhesive, the thickness of the second adhesive layer is preferably 50 μm to 1000 μm, more preferably 75 μm to 900 μm, and even more preferably 100 μm to 800 μm.

[0043] The characteristics of the second adhesive layer and the photocurable adhesive constituting the second adhesive layer will be described below, followed by a brief explanation of the noncurable adhesive.

[0044] E-1. Characteristics of the second adhesive layer The glass transition temperature of the second adhesive layer is preferably -3°C or lower, more preferably -5°C or lower, and even more preferably -6°C or lower. On the other hand, the glass transition temperature is preferably -20°C or higher, more preferably -15°C or higher, and even more preferably -13°C or higher. If the glass transition temperature is within this range, a second adhesive layer with excellent impact resistance can be realized.

[0045] The peak-top value of the loss tangent tanδ of the second adhesive layer (i.e., tanδ at the glass transition temperature) is preferably 1.5 or higher, more preferably 1.6 or higher, even more preferably 1.7 or higher, and particularly preferably 1.75 or higher. On the other hand, the upper limit of the peak-top value of tanδ is preferably 3.0 or lower, more preferably 2.5 or lower, and even more preferably 2.3 or lower. If the peak-top value of tanδ is within this range, the second adhesive layer exhibits appropriate deformation behavior (viscoelastic behavior), making it less likely for gaps to form in the irregularly shaped processed portion and suppressing delay bubbles.

[0046] The total light transmittance of the second adhesive layer is preferably 85% or more, and more preferably 90% or more. The haze value of the second adhesive layer is preferably 1.5% or less, and more preferably 1.0% or less.

[0047] E-2. Photocurable adhesive E-2-1. Characteristics of photocurable adhesives The storage modulus of the photocurable adhesive at 60°C before curing is 1.0 × 10⁻⁶, as stated above. 5 It is less than or equal to Pa, preferably 1.0 × 10⁻⁶ 3 Pa~1.0×10 5 Pa is more like 5.0 × 10 3 Pa~8.0×10 4 Pa is more preferably 7.5 × 10 3 Pa~6.0×10 4 The storage modulus of the photocurable adhesive before curing is within this range. If the photocurable adhesive exhibits appropriate deformation behavior (viscoelastic behavior), it can flow well into every corner of the irregularly shaped processed area. As a result, gaps are less likely to form in the irregularly shaped processed area, and delay bubbles can be suppressed. The storage modulus of the photocurable adhesive at 60°C after curing is preferably 5.0 × 10⁻⁶. 3 Pa~5.0×10 5 Pa is more like 7.5 × 10 3 Pa~4.0×10 5 Pa is more preferably 8.0 × 10 3 Pa~3.0×10 5 The storage modulus of the photocurable adhesive after curing is within this range. If the gel elasticity of the second adhesive is low, the residual stress will be small. As a result, delay bubbles can be suppressed.

[0048] The gel fraction of the photocurable adhesive before curing is preferably 0% to 60%, more preferably 0% to 55%, and even more preferably 0% to 50%. If the gel fraction of the photocurable adhesive before curing is within this range, the desired storage modulus can be easily achieved. Therefore, the photocurable adhesive exhibits appropriate deformation behavior (viscoelastic behavior) and can flow well into every corner of the irregularly shaped processed area. As a result, gaps are less likely to form in the irregularly shaped processed area, and delay bubbles can be suppressed. The gel fraction of the photocurable adhesive after curing is preferably 50% to 95%, more preferably 55% to 93%, and even more preferably 60% to 90%. If the gel fraction of the photocurable adhesive after curing is within this range, the cover glass, the first polarizing plate, and the image display cell can be firmly bonded together. As a result, delay bubbles can be suppressed. The gel fraction can be determined as the insoluble portion in a solvent such as ethyl acetate. Specifically, the gel fraction is determined as the weight fraction (in weight %) of the insoluble components of the adhesive that constitutes the adhesive layer after immersion in ethyl acetate at 23°C for 7 days, relative to the sample before immersion. The gel fraction can be adjusted by appropriately setting the type, combination and amount of monomer components that constitute the base polymer of the adhesive, as well as the type and amount of crosslinking agent.

[0049] E-2-2. Constituent materials of photocurable adhesives As a photocurable adhesive, any suitable photocurable adhesive (which may be simply referred to as an adhesive composition in this section) can be used, as long as it has the characteristics described above. Examples of base polymers for the adhesive composition include (meth)acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, fluorine polymers, natural rubber, synthetic rubber, and other rubber polymers. Preferably, the adhesive composition contains a (meth)acrylic polymer as the base polymer. This is because it has excellent optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive properties, and also has excellent weather resistance and heat resistance. In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0050] The (meth)acrylic base polymer (hereinafter sometimes simply referred to as the base polymer) preferably has a crosslinked structure.

[0051] E-2-2-1. (Meth)acrylic-based polymer (Meth)acrylic-based polymers contain alkyl (meth)acrylate as the main monomer component. Alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group is preferably used. The alkyl (meth)acrylate may have branched alkyl groups or cyclic alkyl groups. The amount of alkyl (meth)acrylate relative to the total amount of monomer components constituting the (meth)acrylic-based polymer is preferably 40% by weight or more, more preferably 50% by weight or more, and even more preferably 60% by weight or more. From the viewpoint of setting the glass transition temperature (Tg) of the polymer chain within an appropriate range, the amount of alkyl (meth)acrylate having a chain-like alkyl group with 4 to 10 carbon atoms relative to the total amount of monomer components constituting the (meth)acrylic-based polymer is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 45% by weight or more.

[0052] The (meth)acrylic base polymer preferably contains a monomer component having a crosslinkable functional group. With such a configuration, the gel fraction of the adhesive can be adjusted to a desired range. Examples of monomer components having a crosslinkable functional group include hydroxyl group-containing monomers and carboxyl group-containing monomers. When a crosslinked structure is introduced by an isocyanate crosslinking agent, the hydroxyl group acts as the reaction site with the isocyanate group, and when a crosslinked structure is introduced by an epoxy crosslinking agent, the carboxyl group acts as the reaction site with the epoxy group. Preferably, a hydroxyl group-containing monomer is used as the monomer component having a crosslinkable functional group, and a crosslinked structure can be introduced by an isocyanate crosslinking agent. With such a configuration, the crosslinkability of the base polymer can be enhanced, and a highly transparent second adhesive layer can be obtained. Furthermore, with such a configuration, a so-called acid-free adhesive can be realized.

[0053] The amount of hydroxyl group-containing monomer relative to the total amount of monomer components constituting the (meth)acrylic base polymer is preferably 5% to 30% by weight, more preferably 8% to 25% by weight, and even more preferably 10% to 20% by weight. When the amount of hydroxyl group-containing monomer is within this range, the degree of crosslinking (gel fraction) can be increased with a small amount of crosslinking agent, and as a result, the fillability and operability of the deformed parts of the photocurable adhesive before curing can be improved. Furthermore, since unreacted hydroxyl groups can form intermolecular hydrogen bonds after crosslinking, the desired storage modulus can be achieved even with a small gel fraction.

[0054] If the second adhesive layer may come into contact with, for example, a touch panel sensor, it is preferable that the second adhesive layer has a low acid content in order to prevent corrosion of the electrodes by acid components. In this case, the amount of carboxyl group-containing monomer relative to the total amount of monomer components constituting the (meth)acrylic base polymer is preferably 0.5% by weight or less, more preferably 0.1% by weight or less, even more preferably 0.05% by weight or less, and ideally 0 (zero). With such a configuration, the acid content in the photocurable adhesive can be preferably 100 ppm or less, more preferably 70 ppm or less, and even more preferably 50 ppm or less.

[0055] The (meth)acrylic base polymer may contain nitrogen-containing monomers as monomer components. By appropriately containing highly polar monomers such as hydroxyl group-containing monomers, carboxyl group-containing monomers, and nitrogen-containing monomers as monomer components in the (meth)acrylic base polymer, a second adhesive layer with an excellent balance of storage modulus, adhesive retention, and impact resistance can be formed. The amount of highly polar monomers (total of hydroxyl group-containing monomers, carboxyl group-containing monomers, and nitrogen-containing monomers) relative to the total amount of monomer components constituting the (meth)acrylic base polymer is preferably 10% to 45% by weight, more preferably 15% to 40% by weight, and even more preferably 18% to 35% by weight. In particular, it is preferable that the total of hydroxyl group-containing monomers and nitrogen-containing monomers is within the above range. The amount of nitrogen-containing monomers relative to the total amount of monomer components constituting the (meth)acrylic base polymer is preferably 3% to 25% by weight, more preferably 5% to 20% by weight, and even more preferably 7% to 15% by weight.

[0056] (Meth)acrylic polymers may further contain any suitable monomer components depending on the purpose. Specific examples of such monomer components include vinyl monomers such as acid anhydride group-containing monomers, caprolactone adducts of (meth)acrylic acid, sulfonic acid group-containing monomers, phosphate group-containing monomers, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene; cyano group-containing acrylic monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylic acid ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl (meth)acrylate.

[0057] The (meth)acrylic base polymer preferably contains the most alkyl (meth)acrylate as a monomer component, and more preferably the most alkyl (meth)acrylate having a chain alkyl group with 6 or fewer carbon atoms. With such a configuration, the peak top value of tanδ increases, and impact resistance can be improved. The amount of alkyl (meth)acrylate having a chain alkyl group with 6 or fewer carbon atoms relative to the total amount of monomer components constituting the (meth)acrylic base polymer is preferably 30% to 80% by weight, more preferably 35% to 75% by weight, and even more preferably 40% to 70% by weight. In particular, it is preferable that the content of butyl acrylate as a monomer component is within the above range.

[0058] The glass transition temperature (Tg) of the (meth)acrylic-based polymer is preferably -50°C or higher. On the other hand, the Tg of the (meth)acrylic-based polymer is preferably -5°C or lower, more preferably -10°C or lower, and even more preferably -15°C or lower.

[0059] E-2-2-2.Crosslinked structure Polymers in which a crosslinked structure has been introduced into a (meth)acrylic base polymer can be obtained, for example, by (1) polymerizing a (meth)acrylic polymer having functional groups that can react with a crosslinking agent, then adding the crosslinking agent and reacting the (meth)acrylic polymer with the crosslinking agent; and (2) introducing a branched structure (crosslinked structure) into the polymer chain by including a polyfunctional compound in the polymerization components of the polymer. These methods may be used in combination.

[0060] Specific examples of crosslinking agents in the method of reacting the base polymer with the crosslinking agent as described in (1) above include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred because they have high reactivity with the hydroxyl groups and carboxyl groups of the base polymer and facilitate the introduction of a crosslinked structure. These crosslinking agents react with functional groups such as hydroxyl groups and carboxyl groups introduced into the base polymer to form a crosslinked structure. As described above, when using an acid-free adhesive in which the base polymer does not contain carboxyl groups, it is preferable to introduce a crosslinked structure using an isocyanate-based crosslinking agent with the hydroxyl groups in the base polymer.

[0061] The crosslinking agent can be used in a ratio of preferably 0.03 to 0.5 parts by weight, more preferably 0.05 to 0.3 parts by weight, even more preferably 0.06 to 0.25 parts by weight, and particularly preferably 0.07 to 0.2 parts by weight, per 100 parts by weight of the base polymer. By using the amount of crosslinking agent within this range, the gel fraction can be set to the desired range described above.

[0062] E-2-2-3. Polyfunctional compounds In the method of including a polyfunctional compound as the polymerization component of the base polymer described in (2) above, the entire amount of monomer components constituting the (meth)acrylic base polymer and the polyfunctional compound for introducing the crosslinking structure may be reacted at once, or polymerization may be carried out in multiple steps. As a method of carrying out polymerization in multiple steps, it is preferable to polymerize (prepolymerize) the monofunctional monomers constituting the (meth)acrylic base polymer to prepare a partial polymer (prepolymer composition), and then add a polyfunctional compound such as a polyfunctional (meth)acrylate to the prepolymer composition to polymerize the prepolymer composition and the polyfunctional monomer (main polymerization). The prepolymer composition is a partial polymer containing polymers with a low degree of polymerization and unreacted monomers.

[0063] By prepolymerizing the components of a (meth)acrylic base polymer, branching points (crosslinking points) by polyfunctional compounds can be uniformly introduced into the (meth)acrylic base polymer. Alternatively, a mixture of a low molecular weight polymer or partially polymerized product and an unpolymerized monomer component (adhesive composition) can be applied to a substrate, and then the main polymerization can be performed on the substrate to form an adhesive layer. Since low polymerization compositions such as prepolymer compositions have low viscosity and excellent applicability, the method of applying an adhesive composition, which is a mixture of a prepolymer composition and a polyfunctional compound, and then performing the main polymerization on the substrate can improve the productivity of the adhesive layer and ensure a uniform thickness of the adhesive layer.

[0064] Examples of polyfunctional compounds used to introduce crosslinked structures include compounds containing two or more polymerizable functional groups (ethylenically unsaturated groups) having unsaturated double bonds in one molecule. Typical polyfunctional compounds are photopolymerizable polyfunctional compounds. Polyfunctional (meth)acrylates are preferred as polyfunctional compounds because they readily copolymerize with monomer components of (meth)acrylic polymers. Polyfunctional (meth)acrylates are also preferred when introducing branched (crosslinked) structures by active energy ray polymerization (photopolymerization).

[0065] The molecular weight of the polyfunctional compound is preferably 1500 or less, more preferably 1000 or less. The lower limit of the molecular weight may be, for example, 500. The functional group equivalent (g / eq) of the polyfunctional compound is preferably 50 to 500, more preferably 70 to 300, and even more preferably 80 to 200. With such a configuration, the viscoelasticity of the photocurable adhesive can be appropriately adjusted.

[0066] The polyfunctional compound may be used in a ratio of preferably 1 to 6 parts by weight, more preferably 2 to 5 parts by weight, and even more preferably 2.5 to 4 parts by weight, per 100 parts by weight of the base polymer. If the amount used is too small, the adhesion retention of the photocurable adhesive (and consequently the second adhesive layer) may be insufficient. If the amount used is too large, the formed second adhesive layer may become excessively hard, resulting in insufficient impact resistance. Furthermore, the processability and / or dimensional stability of the photocurable adhesive may be insufficient.

[0067] In one embodiment, the polyfunctional compound may preferably be a compound containing three or more photopolymerizable functional groups in one molecule, and more preferably a (meth)acrylate containing three or more photopolymerizable functional groups in one molecule. By using a trifunctional or higher photopolymerizable compound, the adhesion retention of the photocurable adhesive (and consequently the second adhesive layer) can be further enhanced. A bifunctional photopolymerizable compound and a trifunctional or higher photopolymerizable compound may be used in combination. The trifunctional or higher photopolymerizable compound may be used in a ratio of preferably 0.5 to 5 parts by weight, more preferably 1 to 4.5 parts by weight, and even more preferably 2 to 4 parts by weight, per 100 parts by weight of the base polymer.

[0068] E-2-2-4. Adhesive Compositions The adhesive composition (photocurable adhesive) may include, in addition to the base polymer, crosslinking agent, and polyfunctional compound described above, a photopolymerization initiator, oligomer, silane coupling agent, and any suitable additives depending on the purpose.

[0069] Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. Photopolymerization initiators may be used alone or in combination of two or more. The content of the photopolymerization initiator in the adhesive composition is preferably 0.01 to 5 parts by weight, and more preferably 0.05 to 3 parts by weight, per 100 parts by weight of the base polymer.

[0070] Any suitable oligomer can be used as the oligomer. By using an oligomer, the viscoelasticity (and therefore the ability to fill irregularly shaped parts and workability) and adhesive strength of the photocurable adhesive can be adjusted. The oligomer is preferably a (meth)acrylic oligomer. (Meth)acrylic oligomers may have excellent compatibility with the base polymer.

[0071] The weight-average molecular weight of the oligomer is preferably around 1,000 to 30,000, more preferably 1,500 to 10,000, and even more preferably 2,000 to 8,000. When the weight-average molecular weight of the oligomer is within this range, excellent adhesive strength and adhesion retention can be achieved.

[0072] The Tg of the oligomer is preferably 20°C or higher, more preferably 50°C or higher, even more preferably 80°C or higher, and particularly preferably 100°C or higher. On the other hand, the Tg of the oligomer is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. If the Tg of the oligomer is within this range, a second adhesive layer with excellent adhesive strength can be formed.

[0073] The oligomer content in the adhesive composition is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the base polymer. Within this oligomer content range, a second adhesive layer with excellent adhesive strength can be formed while maintaining good processability and dimensional stability of the photocurable adhesive.

[0074] Any suitable silane coupling agent can be used. The adhesive strength of the photocurable adhesive can be adjusted by using a silane coupling agent. The content of the silane coupling agent in the adhesive composition is preferably 0.01 to 5 parts by weight, and more preferably 0.03 to 2 parts by weight, per 100 parts by weight of the base polymer.

[0075] Regarding additives, any appropriate additive may be used depending on the purpose.

[0076] In one embodiment, the adhesive composition (photocurable adhesive) may be provided as an adhesive sheet having a thickness corresponding to the thickness of the second adhesive layer, with release films temporarily attached to both sides.

[0077] Further details regarding the adhesive composition (photocurable adhesive) are described in Japanese Patent Application No. 2018-218422, filed by the present applicant. The contents of that application are incorporated herein by reference.

[0078] E-3. Non-curing adhesive As the non-curing adhesive, any suitable non-curing adhesive can be used as long as it has the characteristics described above. By appropriately adjusting the type, combination and amount of monomer components, as well as the type, number, combination and amount of crosslinking agents, silane coupling agents and additives, a non-curing adhesive (resulting in a second adhesive layer) having the desired storage modulus can be obtained. Examples of non-curing adhesives include the adhesives described in Section C above for the first and second adhesive layers, the adhesive described in Japanese Patent Application No. 2019-196942 by the present applicant, and the adhesive described in Japanese Patent Publication No. 2016-94569. The descriptions in said application and publication are incorporated herein by reference.

[0079] E-4. Set of optical components As described above, the adhesive (adhesive composition) constituting the second adhesive layer may be provided as an adhesive sheet. In the fabrication of an image display device, the adhesive sheet may be provided as a set of optical components together with a polarizing plate according to an embodiment of the present invention. Therefore, such a set of optical components is also included in the embodiments of the present invention. In one embodiment, the set of optical components may further include another polarizing plate (backside polarizing plate). That is, in the fabrication of an image display device, the adhesive sheet, the polarizing plate according to an embodiment of the present invention (viewing-side polarizing plate), and the second polarizing plate (backside polarizing plate) may be provided as a set of optical components. [Examples]

[0080] 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.

[0081] (1) Size of the void in the adhesive The cross-sectional state of the adhesive layer in the through-holes of the polarizing plates used in the examples and comparative examples was observed with an optical microscope. The length of the portion where the adhesive layer was most missing from the outer edge in the planar direction was measured and defined as the size L (μm) of the adhesive void. (2) Amount of glue slippage The polarizing plates used in the examples and comparative examples were bonded to glass, autoclaved (50°C / 0.5MPa / 15min), and then subjected to a heating test (85°C, 120h). The through-holes in the samples after the test were observed with an optical microscope, and the deformation of the adhesive at the edge of the polarizing plate in the through-hole was measured and defined as the displacement of the through-hole. The deformation was measured using an optical microscope (MX61L) manufactured by OLYMPUS. Measurements were performed on three test samples, and the maximum value among the three measured values ​​was defined as the displacement. (3) Bubble evaluation The image display device compatible products obtained in the examples and comparative examples were subjected to vacuum lamination followed by autoclaving (50°C / 0.5MPa / 15min) and UV curing (illuminance 150mW / cm²). 2 A radiation dose of 3000 mJ was then applied. Afterwards, the samples were subjected to a heating test (85°C, 24 hours), and the state of bubbles was observed visually or under an optical microscope upon removal. Measurements were performed with n=6 and evaluated according to the following criteria. 4: No bubbles were observed in any of the samples. 3: Less than half of the samples showed slight bubbles, but this does not affect their usability. 2: More than half of the samples showed slight air bubbles, but this does not affect their usability. 1: All samples contain air bubbles.

[0082] <Manufacturing Example 1: Preparation of Adhesive Layer (1)> A monomer mixture containing 99 parts butyl acrylate (BA) and 1 part 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 flask 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 an acrylic polymer solution. To 100 parts of the solid content of the obtained acrylic polymer solution, 0.3 parts of benzoyl peroxide (product name: Naiper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.) as a crosslinking agent, 0.1 parts of isocyanate crosslinking agent (product name: Takenate D110N, manufactured by Mitsui Chemicals, Inc.), and 0.2 parts of silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain an adhesive composition. Next, a solution of the above acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone-based release agent, so that the thickness of the adhesive layer after drying would be 20 μm. The solution was then dried at 155°C for 1 minute to form an adhesive layer (1) on the surface of the separator film. The creep value of the adhesive layer (1) was 120 μm / hr.

[0083] <Manufacturing Example 2: Preparation of Adhesive Layer (2)> A monomer mixture containing 94.9 parts butyl acrylate (BA), 5 parts acrylic acid, and 0.1 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 flask 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 an acrylic polymer solution. To 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 parts of benzoyl peroxide (product name: Naiper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.) as a crosslinking agent, 8 parts of isocyanate-based crosslinking agent (product name: Coronate L, manufactured by Tosoh Corporation), and 0.2 parts of silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain an adhesive composition. Next, a solution of the above acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone-based release agent, so that the thickness of the adhesive layer after drying would be 20 μm. The solution was then dried at 155°C for 1 minute to form an adhesive layer (2) on the surface of the separator film. The creep value of the adhesive layer (2) was 35 μm / hr.

[0084] <Manufacturing Example 3: Preparation of Photocurable Adhesive Constituting the Second Adhesive Layer> A monomer mixture containing 65 parts butyl acrylate (BA), 5 parts cyclohexyl acrylate (CHA), 10 parts N-vinyl-2-pyrrolidone (NVP), 15 parts 4-hydroxybutyl acrylate (4HBA), and 5 parts isostearyl acrylate (ISTA) was charged. Furthermore, 0.2 parts 2,2'-azobisisobutyronitrile as a polymerization initiator and 0.065 parts α-thioglycerol (TGR) as a chain transfer agent were charged to 100 parts of the monomer mixture (solids) together with 233 parts by weight of ethyl acetate, and the mixture was stirred for 1 hour under a nitrogen atmosphere at 23°C, followed by nitrogen purging. The mixture was then reacted at 56°C for 5 hours, and then at 70°C for 3 hours to prepare a solution of acrylic-based polymer. To the above-obtained acrylic-based polymer solution, the following post-addition components were added per 100 parts of the base polymer and homogeneously mixed to prepare photocurable adhesive b. The storage modulus of photocurable adhesive b at 60°C before curing is 4.7 × 10⁻⁶. 4 The storage modulus at 60°C after curing is 1.0 × 10⁻⁶ Pa, and the storage modulus at 60°C is 1.0 × 10⁻⁶ Pa. 5 The temperature was Pa. Furthermore, the gel fraction before curing was 40%, and the gel fraction after curing was 80%. (Later added ingredients) Dipentaerythritol hexaacrylate as a polyfunctional compound (photocuring agent): 2 parts Polypropylene glycol diacrylate (product name: APG400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., polypropylene glycol #400 (n=7) diacrylate, functional group equivalent 268 g / eq) as a polyfunctional compound (photocuring agent): 3 parts Photopolymerization initiator (product name: Irgacure184, manufactured by BASF): 0.2 parts (Preparation of adhesive sheets) A 75 μm thick polyethylene terephthalate (PET) film (Mitsubishi Chemical's "Diafoil MRF75") with a silicone-based release layer on its surface was coated with a photocurable adhesive b. The film was heated at 100°C for 3 minutes to remove the solvent, and then the same release PET film was laminated to the surface. The resulting laminate was aged at 25°C for 3 days to obtain an adhesive sheet I with release films temporarily attached to both sides.

[0085] <Manufacturing Example 4: Fabrication of Polarizing Plates> A 30 μm thick polyvinyl alcohol film was stretched to 3 times its original size 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. A hard-coated triacetylcellulose (TAC) film (hard coat thickness 2 μm, TAC thickness 25 μm) as the outer protective layer and a TAC film (thickness 25 μm) as the inner protective layer were laminated to both sides of this polarizer. Liquid crystal alignment solidification layers H and Q were sequentially transferred to the inner protective layer side of this polarizer. In this way, polarizer (1) was fabricated. The liquid crystal alignment solidification layer H and the liquid crystal alignment solidification layer Q were prepared as follows.

[0086] A liquid crystal composition (coating solution) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (BASF: trade name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film (38 μm thick) was rubbed using a rubbing cloth to perform an orientation treatment. The orientation direction was set so that, when bonded to a polarizing plate, it was 15° from the viewing side relative to the direction of the polarizer's absorption axis. The liquid crystal coating solution was applied to this orientation-treated surface using a bar coater and heated and dried at 90°C for 2 minutes to orient the liquid crystal compound. The liquid crystal layer thus formed was subjected to a 1 mJ / cm³ treatment using a metal halide lamp. 2A liquid crystal alignment solidification layer H was formed on a PET film by irradiating it with light and curing the liquid crystal layer. The thickness of the liquid crystal alignment solidification layer H was 2.5 μm, and the in-plane phase difference Re(550) was 270 nm. Furthermore, the liquid crystal alignment solidification layer H had a refractive index distribution of nx>ny=nz. A liquid crystal alignment solidification layer Q was formed on a PET film in the same manner as above, except that the coating thickness was changed and the orientation processing direction was set to 75° from the viewing side relative to the direction of the polarizer's absorption axis. The thickness of the liquid crystal alignment solidification layer Q was 1.5 μm, and the in-plane phase difference Re(550) was 140 nm. Furthermore, the liquid crystal alignment solidification layer Q had a refractive index distribution of nx>ny=nz.

[0087] <Manufacturing Example 5: Fabrication of Polarizing Plates> A 30 μm thick polyvinyl alcohol film was stretched to 3 times its original size 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 stretch 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 immersing it 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 polarizer with a thickness of 12 μm. A hard-coated triacetylcellulose (TAC) film (hard coat thickness 2 μm, TAC thickness 25 μm) as an outer protective layer and an acrylic resin film (thickness 20 μm) as an inner protective layer were laminated to both sides of this polarizer to create a polarizing plate (2).

[0088] <Manufacturing Example 6: Fabrication of Polarizing Plates> 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 polarizing film was 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 transmittance (Ts) of the final polarizing film 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 5.0 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.

[0089] 2. Fabrication of polarizing plates An HC-TAC film was bonded to the polarizer surface of the resin substrate / polarizer laminate obtained above via an ultraviolet-curing adhesive. Specifically, the curing adhesive was applied to a thickness of 1.0 μm and bonded using a roll machine. Then, UV light was irradiated from the HC-TAC film 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 the TAC film (20 μm thick) was bonded to the peeled surface in the same manner as above. In this way, a polarizing plate (3) was fabricated.

[0090] <Example 1> 1. Formation of through holes A polarizing plate (1) with an adhesive layer (1) obtained in Manufacturing Example 1 was formed on the surface of the liquid crystal alignment solidification layer Q of the polarizing plate (1) obtained in Manufacturing Example 4, to create a polarizing plate with an adhesive layer. This polarizing plate with an adhesive layer was punched out to a size of 145 mm in length and 68 mm in width. At this time, it was punched out so that the absorption axis direction of the polarizer was 135° clockwise with respect to the direction of the long side. Furthermore, a through hole with a diameter of 3.9 mm was formed in the upper right corner of the punched polarizing plate with an adhesive layer by end milling. In this way, a polarizing plate (polarizing plate with an adhesive layer) as shown in Figure 1A was manufactured. The |b1-b2| in the obtained polarizing plate was 0 mm. The size L of the adhesive void was 90 μm. This polarizing plate was subjected to the evaluation in (2) above. The results are shown in Table 1.

[0091] 2. Manufacturing of products compatible with image display devices The polarizing plate with the adhesive layer obtained in 1. above was bonded to one side of a glass plate (corresponding to the image display cell) via the adhesive layer. Next, one release film of the adhesive sheet I obtained in Manufacturing Example 3 was peeled off and bonded to a cover glass (manufactured by Matsunami Glass Co., Ltd., 0.8 mm thick) using a roll laminator. Then, the other release film of the adhesive sheet I was peeled off and bonded to the surface of the polarizing plate with the adhesive layer using a vacuum laminator, filling the through-holes with the adhesive sheet. The vacuum lamination conditions were as follows: heating and pressing at 0.2 MPa and 60°C (waiting time 90 seconds), followed by vacuum lamination at 100 Pa for 10 seconds. Furthermore, a metal halide lamp (300 mW / cm²) was used from the cover glass side. 2 ) with an integrated light intensity of 3000 mJ / cm 2 The photocurable adhesive was cured by irradiation with ultraviolet light. Then, it was autoclaved (50°C / 0.5MPa / 15min). In this way, a product compatible with an image display device was fabricated. The obtained product compatible with an image display device was subjected to the bubble evaluation described in (3) above. The results are shown in Table 1.

[0092] <Example 2> A polarizing plate (polarizing plate with adhesive layer) and an image display device compatible product were manufactured in the same manner as in Example 1, except that through holes were formed at the ends in the long-side direction and in the center in the short-side direction. The |b1-b2| distance of the obtained polarizing plate was 41 mm. The size L of the adhesive void was 90 μm. The obtained polarizing plate and image display device compatible product were subjected to the same evaluation as in Example 1. The results are shown in Table 1. In Table 1, the ends in the long-side direction and the center in the short-side direction are simply referred to as "center".

[0093] <Examples 3-7 and Comparative Examples 1-4> Except for the type and size of the polarizing plate, the type of adhesive layer, and the position of the through-hole formation being as shown in Table 1, polarizing plates (polarizing plates with adhesive layer) and compatible products for image display devices were manufactured in the same manner as in Example 1. The size L of the adhesive void was adjusted by changing the feed rate, rotation speed, and cutting amount of the drill during the end milling process to form the through-holes. Here, Examples 4 and 6 correspond to the configuration shown in Figure 1A, Example 7 corresponds to the configuration shown in Figure 1B, and Examples 3 and 5 correspond to the configuration shown in Figure 1C. The obtained polarizing plates and compatible products for image display devices were each subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0094] [Table 1]

[0095] As is clear from Table 1, the polarizing plate of the embodiment of the present invention shows significantly less adhesive displacement in the through-hole portion after heating compared to the comparative example, and delay bubbles are suppressed. [Industrial applicability]

[0096] The polarizing plate 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]

[0097] 11 Polarizer 12 Outer protective layer 13 Inner protective layer 20 Adhesive layer 30 Through holes 100 polarizing plates

Claims

1. It comprises a polarizer, a protective layer disposed on at least one side of the polarizer, and an adhesive layer. A through hole is formed, It has a rectangular shape, and when viewed from the viewing side, the absorption axis direction of the polarizer is 135° clockwise from the direction of the long side, and the through hole is formed in the upper right corner. The thickness of the polarizer is 1 μm to 15 μm. |b １ -b ２ | is 45 mm or less. Polarizing plate: Here, b １ b is the distance from the center of the through hole to one end of the polarizer in the absorption axis direction of the polarizer, and b ２ This is the distance from the center of the through-hole to the other end of the polarizer plate in the absorption axis direction of the polarizer.

2. It comprises a polarizer, a protective layer disposed on at least one side of the polarizer, and an adhesive layer. A through hole is formed, It has a rectangular shape, and when viewed from the viewing side, the absorption axis direction of the polarizer is 45° clockwise from the direction of the long side, and the through hole is formed in the upper left corner. The thickness of the polarizer is 1 μm to 15 μm. |b １ -b ２ | is 45 mm or less. Polarizing plate: Here, b １ b is the distance from the center of the through hole to one end of the polarizer in the absorption axis direction of the polarizer, and b ２ This is the distance from the center of the through-hole to the other end of the polarizer plate in the absorption axis direction of the polarizer.

3. The polarizing plate according to claim 1 or 2, wherein the thickness of the polarizer is 1 μm to 8 μm.

4. The polarizing plate according to any one of claims 1 to 3, wherein the creep value of the adhesive layer is 35 μm / hr to 140 μm / hr: Here, creep value refers to the amount of displacement of the adhesive from the support plate after 1 hour when a 500g load is applied vertically downwards while the adhesive constituting the adhesive layer is attached to the support plate at 85°C and the support plate with the adhesive attached is fixed in place.

5. The image display cell and the polarizing plate according to any one of claims 1 to 4 are included. The polarizing plate is attached to the image display cell via the adhesive layer. Image display device.

6. A polarizing plate according to claim 1, 2, or 4, a separate adhesive layer provided on the side of the polarizer of the polarizing plate opposite to the adhesive layer, and a cover glass bonded via the separate adhesive layer, The aforementioned through-hole is filled with the adhesive that constitutes the other adhesive layer. The thickness of the polarizer is 1 μm to 15 μm. |b １ -b ２ | is 45 mm or less, Polarizing plate with cover glass: Here, b １ b is the distance from the center of the through hole to one end of the polarizer in the absorption axis direction of the polarizer, and b ２ This is the distance from the center of the through-hole to the other end of the polarizer plate in the absorption axis direction of the polarizer.

Images