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

Abstract

The present application provides a polarizing plate, which has a small shift in a through-hole portion even in a high-temperature environment, and in an image display device, when a through-hole is used to fill an adhesive that covers a glass laminate, bubbles in the through-hole portion can be significantly inhibited. The polarizing plate of the present application has a polarizing plate, a protective layer disposed on at least one side of the polarizing plate, and an adhesive layer, and a through-hole is formed, the thickness of the polarizing plate is 15 μm or less, and |b1-b2| is 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 polarizing plate, 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 polarizing plate.

Description

Technical Field

[0001] This invention relates to a polarizing plate, a polarizing plate with a cover glass, and an image display device. More specifically, this invention relates to a polarizing plate having an adhesive layer and through holes, a polarizing plate with a cover glass, and an image display device comprising such a polarizing plate. Background Technology

[0002] Polarizing plates are widely used in image display devices such as mobile phones and laptop computers to achieve image display and / or improve the performance of that display. In recent years, there has been a desire to use polarizing plates in image display devices with cameras, smartwatches, and automotive dashboards, with some polarizing plates having through-holes. However, in polarizing plates with through-holes, there is a problem where, under high-temperature conditions, the polarizing plate shifts at the through-hole portion (essentially a shift in the adhesive layer).

[0003] However, to impart surface hardness and impact resistance to image display devices, glass is sometimes used as the outermost surface layer of the image display device. When glass is laminated in an image display device that includes a polarizing plate with through-holes, the through-holes are typically used to fill the adhesive layer of the glass. However, in image display devices where the through-holes are filled with adhesive, air bubbles can form in the filled portion (through-hole portion) due to heat treatment or other processes during manufacturing.

[0004] Previous technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2017 / 047510

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-094569 Summary of the Invention

[0008] The present invention addresses the aforementioned prior issues, and its main objective is to provide a polarizing plate that exhibits minimal displacement in the through-hole portion even under high-temperature conditions, and in image display devices, significantly suppresses air bubbles in the through-hole portion when the through-hole is used to fill the adhesive covering the glass laminate.

[0009] 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; and has a through hole formed therein. The thickness of the polarizer is 15 μm or less, and |b1-b2| is 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.

[0010] In one embodiment, the polarizing plate has a rectangular shape, and when viewed from the viewing side, the absorption axis of the polarizer is oriented at a 135° clockwise direction from the long side, with the through-hole formed at the upper right corner. In another embodiment, the polarizing plate has a rectangular shape, and when viewed from the viewing side, the absorption axis of the polarizer is oriented at a 45° clockwise direction from the long side, with the through-hole formed at the upper left corner. Furthermore, in yet another embodiment, the polarizing plate has a rectangular shape, the absorption axis of the polarizer is oriented along the short side, and when viewed from above, the through-hole is formed at the end of the long side and the center of the short side.

[0011] In one embodiment, the thickness of the polarizer is less than 8 μm.

[0012] In one embodiment, the creep value of the adhesive layer is below 140 μm / hr.

[0013] According to another aspect of the present invention, an image display device is provided. The image display device includes an image display unit and the polarizing plate, the polarizing plate being attached to the image display unit via the adhesive layer.

[0014] According to another embodiment of the present invention, a polarizing plate with a cover glass is provided. The polarizing plate with the cover glass includes: a polarizer; a protective layer disposed on at least one side of the polarizer; an adhesive layer; another adhesive layer disposed on the side of the polarizer opposite to the adhesive layer; and a cover glass bonded to the polarizer via the other adhesive layer; and having a through-hole filled with adhesive constituting the other adhesive layer, wherein the thickness of the polarizer is 15 μm or less, and |b1-b2| is 45 mm or less.

[0015] According to an embodiment of the present invention, a polarizing plate having a through hole can be realized, and even in a high-temperature environment, the displacement in the through hole portion is small, and in an image display device, when the through hole is used to fill the adhesive covering the glass laminate, air bubbles in the through hole portion can be significantly suppressed. Attached Figure Description

[0016] Figure 1A A schematic top view illustrating the formation location of the through hole in a polarizing plate according to an embodiment of the present invention.

[0017] Figure 1B A schematic top view illustrating the formation location of the through hole in a polarizing plate according to another embodiment of the present invention.

[0018] Figure 1CA schematic top view illustrating the formation location of the through hole in a polarizing plate according to another embodiment of the present invention.

[0019] Figure 2 This is a schematic cross-sectional view of the through hole portion of the polarizing plate according to an embodiment of the present invention.

[0020] Figure 3 An enlarged cross-sectional view of the main offset portion in the through-hole portion of the polarizing plate in an embodiment of the present invention. Detailed Implementation

[0021] 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. Furthermore, the drawings are shown in a schematic manner for ease of observation, and therefore, the ratios of length, width, thickness, etc., and angles in the drawings differ from those in reality.

[0022] A. Overall Structure of the Polarizing Plate

[0023] Figure 1A A schematic top view illustrating the formation location of the through hole in a polarizing plate according to an embodiment of the present invention; Figure 1B A schematic top view illustrating the formation location of the through hole in a polarizing plate according to another embodiment of the present invention; Figure 1C A schematic top view illustrating the formation location of the through hole in a polarizing plate according to another embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of the through-hole portion of the polarizing plate. The polarizing plate according to an embodiment of the present invention (polarizing plates 100, 101, and 102 in the examples) includes: a polarizer 11; a protective layer (hereinafter, sometimes referred to as an outer protective layer) 12 disposed on one side of the polarizer 11; a protective layer (hereinafter, sometimes referred to as an 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 attach the polarizing plate 100 to an image display unit. Depending on the purpose and desired configuration, either the outer protective layer 12 or the inner protective layer 13 may be omitted.

[0024] A through-hole 30 is formed in the polarizing plate. By forming the through-hole, for example, in the case of a camera built into an image display device, adverse effects on the camera's performance can be prevented. The through-hole can be formed by various methods, such as laser processing, cutting with an end mill, or punching with a Thomson cutter or Pinnacle (registered trademark) cutter. The polarizing plate is typically rectangular in shape. In this specification, the term "rectangular shape" also includes shapes that include irregularly shaped machining portions, such as... Figures 1A to 1CThe R-shape shown has its vertices chamfered. Although not shown, multiple through holes can be provided. The top view shape of the through holes can be any suitable shape depending on the purpose. Specific examples of top view shapes include circles, ellipses, squares, rectangles, and combinations thereof (e.g., rectangles with rounded ends) as shown in the example. Furthermore, irregularly shaped processing parts (e.g., U-shaped notches, V-shaped notches) can be provided at the same time as the through holes. The inventors have discovered a new problem: when through holes are formed on a polarizing plate, at high temperatures, the polarizing plate shifts at the through hole portion (essentially a shift of the adhesive layer: hereinafter sometimes referred to as paste shift), resulting in concerns about light leakage at the through hole portion; this problem is solved by adopting the specific configuration of the embodiment of the present invention (described later). That is, the present invention solves a new problem unknown until now, and the resulting effect is unexpectedly excellent. Furthermore, the inventors have discovered that by adopting the specific configuration of the embodiment of the present invention (described later), bubbles known as delayed bubbles can also be significantly suppressed. Details regarding delayed bubbles are as follows. To impart surface hardness and impact resistance to image display devices, a glass overlay exists on the outermost surface of the device. In the case of an image display device with a polarizing plate containing through-holes, the through-holes are typically used to fill the adhesive layer of the overlay. This filling is typically performed by vacuum lamination of the overlay and adhesive sheet laminate to the polarizing plate. In most cases, no identifiable bubbles are present immediately after vacuum lamination, but bubbles may appear during subsequent heat durability tests of the image display device. These bubbles are typically caused by the shrinkage stress of the polarizing plate applied to the filled area. These bubbles are referred to as delayed bubbles. Delayed bubbles are larger, not fine, bubbles that occupy a certain percentage or more of the top-view area of ​​the through-hole. Delayed bubbles are unacceptable both from an aesthetic point of view and from the perspective of camera performance in the camera section located corresponding to the through-hole. Therefore, suppressing delayed bubbles significantly improves the commercial value of the image display device.

[0025] 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, further preferably 7 μm or less, particularly preferably 6 μm or less, and especially preferably 5 μm or less. The thickness of the polarizer is, for example, 1 μm or more, and may also be, 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 paste shift) that may be caused by thermal shrinkage of the polarizer can be suppressed.

[0026] 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, further preferably 10 mm or less, and especially preferably 5 mm or less. The smaller |b1-b2| is, the better, ideally zero. If |b1-b2| is within this range, the paste shift in the through-hole portion under high-temperature conditions can be reduced, and delayed bubbles can be suppressed. On the other hand, |a1-a2| substantially does not contribute to suppressing paste shift in the through-hole portion or suppressing delayed bubbles. That is, even if |a1-a2| is changed, paste shift and delayed bubbles will not be suppressed. Here, b1 is the distance from the center of the through-hole to one end of the polarizer along the absorption axis of the polarizer, b2 is the distance from the center of the through-hole to the other end of the polarizer along the absorption axis of the polarizer, a1 is the distance from the center of the through-hole to one end of the polarizer in a direction orthogonal to the absorption axis of the polarizer, and a2 is the distance from the center of the through-hole to the other end of the polarizer in a direction orthogonal to the absorption axis of the polarizer. That is, by optimizing the orientation of the polarizer's absorption axis relative to the through-hole, paste shift and delayed bubbles can be suppressed.

[0027] Reference Figures 1A to 1C The relationship between a1, a2, b1, b2 and the formation position of the through hole is explained in detail. Figure 1A The image shows a configuration where the polarizer is rectangular, and when viewed from the viewing side of the image display device (opposite to the adhesive layer), the absorption axis direction A of the polarizer is 135° clockwise relative to the long side direction. In this configuration, when |b1-b2| is optimized, if the through-hole 30 is formed on a straight line extending from the upper right corner in a direction orthogonal to the absorption axis direction A when viewed from the viewing side of the polarizer... Figure 1A In the diagram, any position on the straight line (a1 and a2) can suppress paste shift and delayed bubble formation. On the other hand, by adjusting |a1-a2| to minimize the impact on image display, the through-hole 30 can be preferably formed in the upper right corner. Figure 1B The image shows a configuration where the polarizer is rectangular, and when viewed from the viewing side of the image display device, the absorption axis direction A of the polarizer is at a 45° clockwise angle relative to the long side direction. In this configuration, both paste shift and delayed bubble formation can be suppressed by optimizing |b1-b2|, and the impact on image display can be minimized by adjusting |a1-a2|. Consequently, in this configuration, the through-hole 30 can be preferably formed in the upper left corner. Figure 1CThe diagram shows a configuration where the polarizer is rectangular, and the absorption axis A of the polarizer is along its shorter side (orthogonal to the longer side). In this configuration, both paste shift and delayed bubbles can be suppressed by optimizing |b1-b2|, and the impact on image display can be minimized by adjusting |a1-a2|. Consequently, in this configuration, the through-hole 30 can be preferably formed at the end of the longer side and the center of the shorter side. As can be seen from the description, according to the embodiment of the present invention, regardless of the planar shape of the polarizer (e.g., even in cases with a special planar shape), the relationship between the position of the through-hole that suppresses paste shift and delayed bubbles and the absorption axis direction can be determined by optimizing |b1-b2|. Furthermore, the impact of the through-hole on image display can be minimized by adjusting |a1-a2|.

[0028] In one implementation, such as Figure 3 As shown, with the polarizing plate 100 bonded to the glass plate (which can correspond to the substrate of the image display unit) 120 via the adhesive layer 20, after subjecting the polarizing plate 100 to a heating test at 85°C for 120 hours, the offset (paste offset) D in the through-hole 30 portion is preferably 150 μm or less, more preferably 120 μm or less, further preferably 100 μm or less, particularly preferably 80 μm or less, and especially preferably 50 μm or less. The smaller the offset D, the better. The lower limit of the paste offset D is, for example, 10 μm, or, for example, 20 μm. Furthermore, the paste offset D refers to the maximum portion of the polarizing plate furthest from the through-hole portion when viewed in cross-section. The reference point for the through-hole portion is representatively the lower end of the adhesive layer. That is, when the polarizer plate shifts primarily due to the contraction of the polarizer 11 (to the right in the example shown), the shift is observed at the through-hole portion because the adhesive layer 20 remains on the bonded glass plate 120. Furthermore, as... Figure 3 As shown, a representative feature of the polarizing plate is that the portion of the plate with the through hole is offset away from the through hole. Figure 3 The right side of the middle section, and the portion opposite it, is offset in a manner that protrudes into the through hole. Figure 3 (Left side of the image). As described above, according to the embodiments of the present invention, the newly discovered problem of paste shift occurring in the through-hole portion under high temperature conditions can be solved. Specifically, the paste shift amount D after a specific heating test can be set to the range described above.

[0029] In one embodiment, the polarizing plate may form an adhesive void at the end face of the adhesive layer 20 in the through hole 30 portion, such that it is closer to the inner side in the surface direction than the end face of the polarizing plate (which is essentially the polarizer 11 or the inner protective layer 13 (if present)). The size of the adhesive void is preferably 300 μm or less, more preferably 200 μm or less, further 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" refers to the maximum length from the end face of the polarizing plate (which is essentially the polarizer 11 or the inner protective layer 13 (if present)) to the end face of the adhesive layer 20.

[0030] In embodiments of the present invention, the dimensional shrinkage rate of the polarizing plate after the 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; the lower limit of the dimensional shrinkage rate can be, for example, 0.01%. Furthermore, the dimensional shrinkage rate is calculated by the following formula. The dimensional shrinkage rate is the overall dimensional shrinkage rate of the polarizing plate attached to the glass plate. In the case where the polarizing plate further has an optical functional layer (e.g., a retardation layer, a reflective polarizer), as described below, it refers to the overall dimensional shrinkage rate of the polarizing plate including the optical functional layer. Furthermore, in the following formula, "dimensionality" refers to the dimension along the absorption axis of the polarizing plate (essentially a polarizer).

[0031] Dimensional shrinkage (%) = {(Dimensions before heating test - Dimensions after heating test) / Dimensions before heating test} × 100

[0032] 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 through-hole diameter is, for example, 1.5 mm, or, for example, 2 mm. The ratio D / R of the paste offset D to the through-hole diameter 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 an embodiment of the present invention, since the paste offset D is very small as described above, D / R can be set to this range even when the through-hole diameter is reduced. Therefore, even when the through-hole diameter is reduced, it is substantially possible to prevent adverse effects on camera performance. As a result, the polarizing plate of the embodiment of the present invention can be applied to image display devices where only the camera section is a non-display area and / or borderless image display devices.

[0033] The polarizing plate of the embodiments of the present invention can be used as a viewing-side polarizing plate or a rear-side polarizing plate. Furthermore, the polarizing plate of the embodiments of the present invention can also have any suitable optical functional layer depending on the purpose. Examples of optical functional layers include a phase retardation layer, a conductive layer for a touch panel, and a reflective polarizer.

[0034] In one embodiment, a phase retardation layer may be provided between the inner protective layer 13 and the adhesive layer 20. The phase retardation layer may be a single layer or have a laminated structure. When the phase retardation layer is a single layer, it typically functions as a λ / 4 plate. In this case, the in-plane phase difference Re(550) of the phase retardation 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 formed by the absorption axis of the polarizer and the lag axis of the phase retardation layer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 46°. The phase retardation layer preferably exhibits inverse wavelength dispersion characteristics, where the phase difference value increases with the wavelength of the measured light. In this case, the Re(450) / Re(550) ratio of the phase retardation layer is preferably 0.8 or higher and less than 1, more preferably 0.8 or higher and less than 0.95. The phase retardation layer can be an extension of the resin film or an alignment and curing layer of the liquid crystal compound. When the phase retardation layer is made of a resin film, the phase retardation layer can also serve as an inner protective layer. For example, Japanese Patent Application Publication No. 2017-54093 and Japanese Patent Application Publication No. 2018-60014 describe phase retardation layers made of resin films. For example, specific examples of liquid crystal compounds and details of methods for forming alignment and curing layers are described in Japanese Patent Application Publication No. 2006-163343. The descriptions in these publications are incorporated herein by reference. Furthermore, in this specification, "Re(λ)" refers to the in-plane phase retardation measured at 23°C using light with a wavelength of λnm. For example, "Re(550)" is the in-plane phase difference measured at 23°C using light with a wavelength of 550 nm. As for Re(λ), when the thickness of the layer (film) is set to d (nm), it is obtained by the formula: Re(λ)=(nx-ny)×d. nx is the refractive index in the direction where the in-plane refractive index reaches its maximum (i.e., the direction of the late phase axis), and ny is the refractive index in the direction orthogonal to the late phase axis in the in-plane (i.e., the direction of the advanced phase axis).

[0035] When the retardation layer has a stacked structure, the retardation layer is typically composed of an H layer and a Q layer sequentially from the polarizer side. The H layer typically functions as a λ / 2 plate, while the Q layer usually functions 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 formed between the absorption axis of the polarizer and the lag 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 formed by the absorption axis of the polarizer and the lag axis of the Q layer is preferably 70°–80°, more preferably 72°–78°, and even more preferably 74°–76°. The arrangement order of the H layer and the Q layer can be reversed, and the angles formed by the lag axis of the H layer and the absorption axis of the polarizer, as well as the angles formed by the lag axis of the Q layer and the absorption axis of the polarizer, can also be reversed. The H layer and the Q layer can be extension films of the resin film or alignment and curing layers of the liquid crystal compound, respectively.

[0036] In one embodiment, a conductive layer for the touch panel can be provided on the side of the inner protective layer 13 (which is a phase difference layer if present) opposite to the polarizer. With this configuration, the polarizer can be applied to a so-called internal touch panel type input display device in which a touch sensor is assembled between the image display unit and the polarizer. A representative polarizer of this embodiment is a viewing-side polarizer.

[0037] 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 can also serve as the outer protective layer. A representative polarizer of this embodiment is a back-side polarizer. Details regarding reflective polarizers are described, for example, in Japanese Patent Publication No. 9-507308 and Japanese Patent Publication No. 2013-235259. The descriptions in these publications are incorporated herein by reference.

[0038] When the polarizing plate of the embodiment of the present invention is rectangular, the aspect ratio is preferably 1.3 to 2.5. In this case, the dimensions of the polarizing plate are, for example, 145mm to 155mm in length and 65mm to 75mm in width, or 230mm to 240mm in length and 140mm to 150mm in width. That is, the polarizing plate of the embodiment of the present invention is suitable for use in smartphones or tablet PCs (Personal Computers). As for the size of a smartphone, for example, the length can be 120mm to 200mm and the width can be 30mm to 120mm.

[0039] The following is a detailed description of the polarizer, protective layer, and adhesive layer that make up the polarizer plate.

[0040] B.Polarizing plate

[0041] B-1. Polarizing filter

[0042] Polarizers are typically made of a resin film containing a dichroic substance. Any suitable resin film suitable for use as a polarizer can be used as the resin film. A representative resin film is a polyvinyl alcohol (PVA) film. The resin film can be a single layer or a laminate of two or more layers.

[0043] As a specific example of a polarizer composed of a single-layer resin film, one can exemplify a polarizer made by performing iodine-based dyeing and stretching treatments (typically uniaxial stretching) on ​​a PVA-type resin film. Iodine dyeing is performed, for example, by immersing the PVA-type resin film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing, or simultaneously with dyeing. Alternatively, dyeing can be performed after stretching. Depending on the requirements, the PVA-type resin film may undergo swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-type resin film in water for washing before dyeing, not only can stains or anti-caking agents on the surface of the PVA-type resin film be removed, but the PVA-type resin film can also swell to prevent uneven dyeing.

[0044] As a specific example of a polarizer obtained by using a laminate, examples include polarizers obtained by using a resin substrate and a PVA-type resin layer (PVA-type resin film) laminated on the resin substrate, or a polarizer obtained by using a resin substrate and a PVA-type resin layer coated on the resin substrate. A polarizer obtained by using a laminate of a resin substrate and a PVA-type resin layer coated on the resin substrate can be manufactured, for example, by the following steps: applying a PVA-type resin solution to a resin substrate and drying it to form a PVA-type resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-type resin layer; and then forming a polarizer from the PVA-type resin layer by stretching and dyeing the laminate. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, as needed, include: before stretching in the aqueous boric acid solution, performing aerial stretching of the laminate at a high temperature (e.g., above 95°C). The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer can be laminated onto the peeled surface for use, depending on the purpose. Details of this method for manufacturing polarizers 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.

[0045] The thickness of the polarizer is as described in item A.

[0046] The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The polarization brightness of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0047] B-2. Protective layer

[0048] The protective layer is formed from any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that are the main components of this film include: cellulose resins such as triacetyl cellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrene, and polyvinyl chlorides. Transparent resins such as alkenes, polyolefins, (meth)acrylic acids, and acetates can be used. Examples also include thermosetting resins or UV-curable resins such as (meth)acrylic acids, carbamates, (meth)acrylate carbamates, epoxy resins, and silicone resins. Furthermore, glassy polymers such as siloxane polymers can also be used. Additionally, polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As materials for this film, for example, resin compositions containing thermoplastic resins with substituted or unsubstituted imine groups on the side chains, and thermoplastic resins with substituted or unsubstituted phenyl and nitrile groups on the side chains can be used. Examples include resin compositions containing alternating copolymers of isobutylene and N-methylcis-imide, and acrylonitrile-styrene copolymers. The polymer film can be, for example, an extruded product of the resin composition.

[0049] As needed, the outer protective layer 12 (especially when the polarizing plate is a viewing-side polarizing plate) can be subjected to surface treatments such as hard coating, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment. Furthermore / or, the outer protective layer 12 can also be treated to improve visibility when viewed through polarized sunglasses (typically by imparting (ellipsoidal) polarization or ultra-high phase difference). By implementing this treatment, excellent visibility can be achieved even when viewing the displayed image through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate is also suitable for use in image display devices suitable for outdoor applications.

[0050] 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 at 23°C using light with a wavelength of λ nm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550 nm. Rth(λ) is calculated using the formula: Rth(λ) = (nx - nz) × d, where nz is the refractive index in the thickness direction.

[0051] The thickness of the protective layer can be any suitable thickness. For example, the thickness of the protective layer is 10 μm to 50 μm, preferably 20 μm to 40 μm. Furthermore, when a surface treatment has been performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0052] C. Adhesive layer

[0053] The adhesive layer 20, as described above, is used to attach the polarizing plate to the image display unit. The adhesive layer is typically composed of an acrylic adhesive (acrylic adhesive composition). The acrylic adhesive composition typically contains a (meth)acrylic polymer as a main component. In the solid component of the adhesive composition, the (meth)acrylic polymer may be contained in the adhesive composition at a rate of 50% or more by weight, preferably 70% or more by weight, and more preferably 90% or more by weight. The (meth)acrylic polymer contains an alkyl (meth)acrylic ester as a monomer unit as a main component. Furthermore, (meth)acrylic esters refer to acrylates and / or methacrylates. The alkyl (meth)acrylic ester is preferably contained in the monomer component forming the (meth)acrylic polymer at a rate of 80% or more by weight, and more preferably 90% or more by weight. Examples of alkyl groups in the (meth)acrylic ester include, for example, straight-chain or branched alkyl groups having 1 to 18 carbon atoms. The alkyl group preferably has an average of 3 to 9 carbon atoms, more preferably 3 to 6. A preferred alkyl methacrylate is butyl acrylate. Examples of monomers (comonomers) constituting alkyl methacrylate polymers, besides alkyl methacrylates, include: monomers containing carboxyl groups, monomers containing hydroxyl groups, monomers containing amide groups, alkyl methacrylates containing aromatic rings, and vinyl monomers containing heterocycles. Representative examples of comonomers include: acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic adhesive composition preferably contains a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include, for example, silane coupling agents containing epoxy groups. Examples of crosslinking agents include, for example, isocyanate crosslinking agents and peroxide crosslinking agents. Furthermore, the acrylic adhesive composition may also contain antioxidants and / or conductive agents. The thickness of the adhesive layer is, for example, 50 μm or less, and more preferably 22 μm or less, as described above, and even more preferably 10 μm to 22 μm. Details of the adhesive layer or acrylic adhesive composition are described, for example, in Japanese Patent Application Publication No. 2006-183022, Japanese Patent Application Publication No. 2015-199942, Japanese Patent Application Publication No. 2018-053114, Japanese Patent Application Publication No. 2016-190996, and International Publication No. 2018 / 008712, the descriptions of which are incorporated herein by reference.

[0054] The creep value of the adhesive layer is preferably below 140 μm / hr, more preferably below 100 μm / hr, further preferably below 75 μm / hr, and most preferably below 50 μm / hr. The lower limit of the creep value can be, for example, 20 μm / hr. In this specification, "creep value" refers to the creep value at 85°C. The creep value can be determined, for example, by the following sequence: applying the adhesive constituting the adhesive layer to a support plate; fixing the support plate with the adhesive attached; and applying a 500g load downwards in the vertical direction in this state. After applying the load for 1 hour, the amount of displacement of the adhesive from the support plate is measured, and this displacement is taken as the creep value (μm / hr).

[0055] The storage modulus G2' of the adhesive layer at -40°C is preferably 1.0 × 10⁻⁶. 5 (Pa) or higher, preferably 1.0 × 10 6 (Pa) or higher, and preferably 1.0 × 10 7 (Pa) or higher, with an optimal value of 1.0 × 10⁻⁶. 8 (Pa) or above. The storage modulus G2' can be, for example, 1.0 × 10⁻⁶. 9 (Pa) or less. The storage modulus G3' of the adhesive layer at 85°C is preferably 1.0 × 10⁻⁶. 5 (Pa) or higher, preferably 3.0×10 5 (Pa) or higher, and preferably 5.0 × 10 5 (Pa) or above. The storage modulus G3' can be, for example, 1.0 × 10⁻⁶. 6 (Pa) and below.

[0056] D. Image display device

[0057] The polarizing plate of the embodiments 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. The image display device includes an image display unit and a polarizing plate. The polarizing plate is the polarizing plate of the embodiments of the present invention described in items A to C. The polarizing plate is attached to the image display unit via an adhesive layer. Examples of image display devices include liquid crystal display devices, organic electroluminescent (EL) display devices, and quantum dot display devices.

[0058] E. Polarizing plate with cover glass

[0059] When the polarizing plate of the embodiment of the present invention is applied to the viewing side of an image display device, the cover glass can be attached to the polarizing plate via another adhesive layer (hereinafter, sometimes referred to as the second adhesive layer). Therefore, the embodiment of the present invention includes a polarizing plate with a cover glass layer. Furthermore, the polarizing plate of the embodiment of the present invention can also be provided in the form of temporarily attaching a spacer instead of a cover glass. In this case, during the manufacture of the image display device, the spacer is peeled off, and the cover glass is attached via the exposed second adhesive layer. In either case, the through-hole is typically filled with the adhesive constituting the second adhesive layer. The adhesive constituting the second adhesive layer will be described below.

[0060] Regarding the adhesive constituting the second adhesive layer, when the second adhesive layer is deposited on the polarizing plate, a representative storage modulus at 60°C is 1.0 × 10⁻⁶. 4 Pa ~ 1.0 × 10 5 Pa. Any suitable adhesive can be used to form the second adhesive layer, as long as it has this storage modulus during lamination. Specifically, the adhesive can be a photocurable adhesive or a non-curable adhesive. Furthermore, in this specification, "photocurable adhesive" refers to an adhesive whose cross-linking reaction is carried out by light irradiation. Therefore, photocurable adhesives are more flexible and have excellent deformability during lamination, and the adhesive layer can be endowed with the required properties (e.g., storage modulus) by light irradiation after lamination. This results in excellent filling properties of the irregularly shaped portions of the photocurable adhesive, allowing for a thinner second adhesive layer (resulting in an image display device). Furthermore, even when a thick border printing layer is formed on the cover glass, good adhesion can be ensured. "Non-curable adhesive" refers to an adhesive whose cross-linking reaction has substantially ended and whose cross-linking reaction does not substantially occur after lamination. In other words, a non-curable adhesive can be a so-called ordinary adhesive. Non-curing adhesives do not require light exposure (light curing), thus offering excellent productivity and preventing issues such as dents, adhesive overflow from the ends of die-cut parts, and operational errors.

[0061] The storage modulus of the photocurable adhesive at 60°C before curing substantially corresponds to the storage modulus during lamination. The storage modulus before curing, as described above, is 1.0 × 10⁻⁶. 5 Below Pa, a value of 1.0 × 10 Pa is preferred. 3 Pa ~ 1.0 × 10 5 Pa. The optimal storage modulus of the light-curing adhesive at 60°C after curing is 5.0 × 10⁻⁶. 3 Pa ~ 5.0 × 10 5Pa. The gel content of the photocurable adhesive before curing is 0% to 60%, and the gel content 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.

[0062] The optimal storage modulus at 60°C for non-curing adhesive lamination is 1.0 × 10⁻⁶. 3 Pa ~ 8.0 × 10 4 Pa, preferably 5.0 × 10 3 Pa ~ 6.0 × 10 4 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.

[0063] The characteristics of the second adhesive layer and the light-curing adhesive constituting the second adhesive layer will be explained below, followed by a brief explanation of the non-curing adhesive.

[0064] E-1. Characteristics of the second adhesive layer

[0065] The glass transition temperature of the second adhesive layer is preferably below -3°C, more preferably below -5°C, and even more preferably below -6°C. On the other hand, the glass transition temperature is preferably above -20°C, more preferably above -15°C, and even more preferably above -13°C. If the glass transition temperature is within this range, a second adhesive layer with excellent impact resistance can be achieved.

[0066] The peak value of the loss tangent tanδ of the second adhesive layer (i.e., tanδ at the glass transfer temperature) is preferably 1.5 or higher, more preferably 1.6 or higher, and even more preferably 1.7 or higher, and particularly preferably 1.75 or higher. On the other hand, the upper limit of the peak 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 value of tanδ is within this range, the second adhesive layer exhibits appropriate deformation behavior (viscoelastic behavior), thus preventing the formation of gaps in irregularly shaped processing sections and suppressing delayed bubbles.

[0067] The total light transmittance of the second adhesive layer is preferably 85% or higher, and more preferably 90% or higher. The haze value of the second adhesive layer is preferably 1.5% or lower, and more preferably 1.0% or lower.

[0068] E-2. Light-curing adhesive

[0069] E-2-1. Characteristics of Light-Curing Adhesives

[0070] The storage modulus of the light-curing adhesive at 60°C before curing, as described above, is 1.0 × 10⁻⁶. 5 Below Pa, a value of 1.0 × 10 Pa is preferred. 3 Pa ~ 1.0 × 10 5 Pa, preferably 5.0 × 10 3 Pa ~ 8.0 × 10 4 Pa, and preferably 7.5 × 10 Pa. 3 Pa ~ 6.0 × 10 4 Pa. If the storage modulus of the photocurable adhesive before curing is within this range, the photocurable adhesive exhibits appropriate deformation behavior (viscoelastic behavior) and can flow well into all corners of the irregularly shaped part. As a result, gaps are less likely to form in the irregularly shaped part, and delayed air bubbles can be suppressed. The preferred storage modulus of the photocurable adhesive at 60°C after curing is 5.0 × 10⁻⁶. 3 Pa ~ 5.0 × 10 5 Pa, preferably 7.5 × 10 3 Pa ~ 4.0 × 10 5 Pa, and preferably 8.0 × 10 Pa. 3 Pa ~ 3.0 × 10 5 Pa. If the storage modulus of the photocurable adhesive after curing is within this range, the gel elasticity of the second adhesive decreases, and the residual stress becomes smaller. As a result, delayed bubbles can be suppressed.

[0071] 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 required storage modulus can be easily achieved. Therefore, the photocurable adhesive exhibits appropriate deformation behavior (viscoelastic behavior) and can flow well into all corners of the irregularly shaped processing section. As a result, gaps are less likely to form in the irregularly shaped processing section, and delayed air 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 unit can be firmly fixed. As a result, delayed air bubbles can be suppressed. The gel fraction can be determined based on the insoluble fraction in solvents such as ethyl acetate. Specifically, the gel fraction is determined by the weight fraction (in weight %) of the insoluble components of 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 types, combinations, and amounts of monomer components of the base polymer constituting the adhesive, as well as the types and amounts of crosslinking agents.

[0072] E-2-2. Constituent Materials of Light-Curing Adhesives

[0073] As a photocurable adhesive, any suitable photocurable adhesive (in this section, sometimes simply referred to as an adhesive composition) can be used, as long as it possesses the properties described above. Examples of base polymers for the adhesive composition include (meth)acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethylene ethers, vinyl acetate / vinyl chloride polymers, modified polyolefins, epoxy polymers, fluoropolymers, natural rubber, synthetic rubber, and other rubber polymers. Preferably, a (meth)acrylic adhesive composition containing a (meth)acrylic polymer as the base polymer is preferred. This is because it exhibits excellent optical transparency, moderate wetting, cohesiveness, and adhesion properties, as well as excellent weather resistance and heat resistance. Furthermore, in this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0074] (Meth)acrylic acid base polymers (hereinafter, sometimes simply referred to as base polymers) preferably have a cross-linked structure.

[0075] E-2-2-1. (Meth)acrylic acid base polymer

[0076] (Meth)acrylate-based polymers contain alkyl (meth)acrylates as the main monomer component. Alkyl (meth)acrylates with alkyl groups having 1 to 20 carbon atoms are suitable as the alkyl (meth)acrylate. The alkyl group of the alkyl (meth)acrylate may be branched or cyclic. The amount of alkyl (meth)acrylate relative to the total amount of monomer components constituting the (meth)acrylate-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 chain-like alkyl groups having 4 to 10 carbon atoms is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 45% by weight or more, relative to the total amount of monomer components constituting the (meth)acrylate-based polymer.

[0077] The (meth)acrylic acid-based base polymer preferably contains monomer components with crosslinkable functional groups. With this configuration, the gel fraction of the adhesive can be adjusted to the desired range. Examples of monomer components with crosslinkable functional groups include monomers containing hydroxyl groups and monomers containing carboxyl groups. When the crosslinking structure is introduced by an isocyanate crosslinking agent, the hydroxyl group becomes the reaction site with the isocyanate group; when the crosslinking structure is introduced by an epoxy crosslinking agent, the carboxyl group becomes the reaction site with the epoxy group. It is preferable to use monomers containing hydroxyl groups as the monomer component with crosslinkable functional groups, thereby allowing the crosslinking structure to be introduced by an isocyanate crosslinking agent. With this configuration, the crosslinkability of the base polymer can be improved, and a second adhesive layer with higher transparency can be obtained. Furthermore, with this configuration, a so-called acid-free adhesive can be achieved.

[0078] Relative to the total amount of monomer components constituting the (meth)acrylic acid base polymer, the amount of hydroxyl-containing monomers is preferably 5% to 30% by weight, more preferably 8% to 25% by weight, and even more preferably 10% to 20% by weight. If the amount of hydroxyl-containing monomers is within this range, the degree of crosslinking (gel fraction) can be increased with a smaller crosslinking dosage. As a result, the fillability and workability of the profiled parts of the photocurable adhesive before curing can be improved. Furthermore, since unreacted hydroxyl groups after crosslinking can form intermolecular hydrogen bonds, the required storage modulus can be achieved even with a lower gel fraction.

[0079] In cases where the second adhesive layer may come into contact with a touch panel sensor, it is preferable to have a low acid content in the second adhesive layer to prevent corrosion of the electrodes by acid components. In this case, the amount of carboxyl-containing monomers is preferably 0.5% by weight or less, more preferably 0.1% by weight or less, and even more preferably 0.05% by weight or less, ideally zero, relative to the total amount of monomer components constituting the (meth)acrylic acid-based polymer. With this configuration, the acid content in the photocurable adhesive is preferably set to 100 ppm or less, more preferably 70 ppm or less, and even more preferably 50 ppm or less.

[0080] (Meth)acrylic acid-based polymers may also contain nitrogen-containing monomers as monomer components. By appropriately including highly polar monomers such as hydroxyl-containing monomers, carboxyl-containing monomers, and nitrogen-containing monomers as monomer components in (meth)acrylic acid-based polymers, a second adhesive layer with an excellent balance of storage modulus, adhesion retention, and impact resistance can be formed. The amount of highly polar monomers (the total of hydroxyl-containing monomers, carboxyl-containing monomers, and nitrogen-containing monomers) is preferably 10% to 45% by weight, more preferably 15% to 40% by weight, and even more preferably 18% to 35% by weight, relative to the total amount of monomer components constituting the (meth)acrylic acid-based polymer. It is particularly preferred that the total amount of hydroxyl-containing monomers and nitrogen-containing monomers is within the aforementioned range. The amount of nitrogen-containing monomers is preferably 3% to 25% by weight, more preferably 5% to 20% by weight, and even more preferably 7% to 15% by weight, relative to the total amount of monomer components constituting the (meth)acrylic acid-based polymer.

[0081] (Meth)acrylate polymers may also contain any suitable monomer components depending on the purpose. Specific examples of such monomer components include: monomers containing anhydride groups, caprolactone adducts of (meth)acrylate, monomers containing sulfonic acid groups, monomers containing phosphoric acid groups, vinyl acetate, vinyl propionate, styrene, α-methylstyrene, and other vinyl monomers; acrylic monomers containing cyano groups such as acrylonitrile and methacrylonitrile; epoxy-containing monomers such as glycidyl (meth)acrylate; glycol acrylate monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylate monomers such as tetrahydrofurfuryl (meth)acrylate, fluoro(meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl (meth)acrylate.

[0082] The (meth)acrylic acid-based polymer preferably contains the most alkyl (meth)acrylic acid esters as monomer components, and more preferably contains the most alkyl (meth)acrylic acid esters with 6 or fewer carbon atoms. With this configuration, the peak value of tanδ increases, improving impact resistance. The amount of alkyl (meth)acrylic acid esters with 6 or fewer carbon atoms is preferably 30% to 80% by weight, more preferably 35% to 75% by weight, and even more preferably 40% to 70% by weight, relative to the total amount of monomer components constituting the (meth)acrylic acid-based polymer. It is particularly preferred that the content of butyl acrylate as a monomer component is within the aforementioned range.

[0083] The glass transition temperature (Tg) of the (meth)acrylic acid-based polymer is preferably -50°C or higher. On the other hand, the Tg of the (meth)acrylic acid-based polymer is preferably -5°C or lower, more preferably -10°C or lower, and even more preferably -15°C or lower.

[0084] E-2-2-2. Crosslinked structure

[0085] The introduction of cross-linked polymers into (meth)acrylic acid-based base polymers can be achieved, for example, by the following methods: (1) polymerizing a (meth)acrylic acid-based polymer having functional groups that can react with a cross-linking agent, and then adding a cross-linking agent to react the (meth)acrylic acid-based polymer with the cross-linking agent; and (2) introducing branched structures (cross-linked structures) into the polymer chain by means of polyfunctional compounds contained in the polymer's polymeric components. These methods can also be used in combination.

[0086] As specific examples of crosslinking agents in the method of reacting the base polymer with the crosslinking agent described in (1), isocyanate crosslinking agents, epoxy crosslinking agents, etc., can be cited. Crosslinking agents include zopyridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. Among these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred due to their high reactivity with the hydroxyl or carboxyl groups of the base polymer, which facilitates the introduction of crosslinking structures. These crosslinking agents react with the functional groups such as hydroxyl or carboxyl groups introduced into the base polymer to form a crosslinking structure. As mentioned above, when using an acid-free adhesive whose base polymer does not contain carboxyl groups, it is preferable to introduce the crosslinking structure through the hydroxyl groups in the base polymer and isocyanate crosslinking agents.

[0087] The crosslinking agent can be used at a ratio of 0.03 to 0.5 parts by weight, more preferably 0.05 to 0.3 parts by weight, further preferably 0.06 to 0.25 parts by weight, and most preferably 0.07 to 0.2 parts by weight, relative to 100 parts by weight of the base polymer. By setting the amount of crosslinking agent used within this range, the gel fraction can be kept within the desired range.

[0088] E-2-2-3. Multifunctional compound

[0089] In the method of including a polyfunctional compound in the polymerization composition of the base polymer described in (2), the monomer components constituting the (meth)acrylic acid base polymer can be reacted with the entire amount of the polyfunctional compound used to introduce the crosslinking structure in one step, or the polymerization can be carried out in multiple stages. As a method of carrying out polymerization in multiple stages, the following method is preferred: a partial polymer (prepolymer composition) is prepared by polymerizing the monofunctional monomers constituting the (meth)acrylic acid base polymer (prepolymerization), and a polyfunctional compound such as a polyfunctional (meth)acrylic acid ester is added to the prepolymer composition to polymerize the prepolymer composition with the polyfunctional monomers (formal polymerization). The prepolymer composition is a partial polymer containing a polymer with a low degree of polymerization and unreacted monomers.

[0090] By prepolymerizing the components of a (meth)acrylic acid-based base polymer, the branching points (crosslinking points) of multifunctional compounds can be uniformly introduced into the (meth)acrylic acid-based base polymer. Alternatively, a low molecular weight polymer or a mixture of a portion of the polymer and unpolymerized monomer components (adhesive composition) can be coated onto a substrate, followed by formal polymerization on the substrate to form an adhesive layer. Since low-polymerization compositions such as prepolymer compositions have low viscosity and excellent coatability, the method of coating a mixture of prepolymer composition and multifunctional compounds (i.e., the adhesive composition) onto a substrate followed by formal polymerization improves the productivity of the adhesive layer and makes its thickness more uniform.

[0091] Examples of multifunctional compounds used to introduce cross-linking structures include compounds containing two or more polymerizable functional groups (vinyl unsaturated groups) with unsaturated double bonds in one molecule. Photopolymerizable multifunctional compounds are representative examples. Considering ease of copolymerization with monomer components of (meth)acrylate polymers, multifunctional (meth)acrylates are preferred as multifunctional compounds. In cases where branched (cross-linked) structures are introduced via active energy line polymerization (photopolymerization), multifunctional (meth)acrylates are preferred.

[0092] The molecular weight of the multifunctional compound is preferably 1500 or less, more preferably 1000 or less. For example, the lower limit of the molecular weight can be 500. The functional group equivalent (g / eq) of the multifunctional compound is preferably 50 to 500, more preferably 70 to 300, and even more preferably 80 to 200. With this configuration, the viscoelasticity of the photocurable adhesive can be appropriately adjusted.

[0093] The multifunctional compound can be used at a ratio of 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 relative to 100 parts by weight of the base polymer. If the amount used is too small, the adhesion retention of the photocurable adhesive (resulting in a second adhesive layer) will be insufficient. If the amount used is too large, the formed second adhesive layer will be too hard and lack impact resistance. Furthermore, the processability and / or dimensional stability of the photocurable adhesive will be insufficient.

[0094] In one embodiment, the multifunctional compound is preferably a compound containing three or more photopolymerizable functional groups per molecule, more preferably a (meth)acrylate containing three or more photopolymerizable functional groups per molecule. By using a photopolymerizable compound with three or more functions, the adhesion retention of the photocurable adhesive (resulting in a second adhesive layer) can be further improved. A photopolymerizable compound with two functions can also be used in combination with a photopolymerizable compound with three or more functions. The photopolymerizable compound with three or more functions can be used at a ratio of preferably 0.5 parts by weight to 5 parts by weight, more preferably 1 part by weight to 4.5 parts by weight, and even more preferably 2 parts by weight to 4 parts by weight relative to 100 parts by weight of the base polymer.

[0095] E-2-2-4. Adhesive Composition

[0096] In addition to the base polymer, crosslinking agent and multifunctional compound, the adhesive composition (photocurable adhesive) may also contain photopolymerization initiator, oligomer, silane coupling agent and any suitable additives as appropriate for the purpose.

[0097] Examples of photopolymerization initiators include: benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, ketal-based photopolymerization initiators, and 9-oxosulfur-based photopolymerization initiators. Photopolymerization initiators, including acylphosphine oxide photopolymerization initiators. Photopolymerization initiators can be used alone or in combination of two or more. The content of the photopolymerization initiator in the adhesive composition relative to 100 parts by weight of the base polymer is preferably 0.01 parts by weight to 5 parts by weight, more preferably 0.05 parts by weight to 3 parts by weight.

[0098] As oligomers, any suitable oligomer can be used. By using oligomers, the viscoelasticity (and thus the filling and workability of profiled parts) and adhesion of the light-curing adhesive can be adjusted. (Meth)acrylic oligomers are preferred. (Meth)acrylic oligomers have excellent compatibility with the base polymer.

[0099] The weight-average molecular weight of the oligomer is preferably about 1,000 to 30,000, more preferably 1,500 to 10,000, and even more preferably 2,000 to 8,000. If the weight-average molecular weight of the oligomer is within this range, excellent adhesion and adhesion retention can be achieved.

[0100] The Tg of the oligomer is preferably 20°C or higher, more preferably 50°C or higher, and 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. When the Tg of the oligomer is within this range, a second adhesive layer with excellent adhesion can be formed.

[0101] The content of oligomers in the adhesive composition is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, relative to 100 parts by weight of the base polymer. If the content of oligomers is within this range, the processability and dimensional stability of the photocurable adhesive can be well maintained, and a second adhesive layer with excellent adhesion can be formed.

[0102] Any suitable silane coupling agent can be used as the silane coupling agent. By using the silane coupling agent, the adhesion of the photocurable adhesive can be adjusted. The content of the silane coupling agent in the adhesive composition is preferably 0.01 parts by weight to 5 parts by weight, and more preferably 0.03 parts by weight to 2 parts by weight, relative to 100 parts by weight of the base polymer.

[0103] Regarding additives, any appropriate additive may be used depending on the purpose.

[0104] 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 and having a release film temporarily adhered to both sides.

[0105] More detailed information about the adhesive composition (light-curing adhesive) is described in Japanese Patent Application No. 2018-218422 filed by the applicant. The description in that application is incorporated herein by reference.

[0106] E-3. Non-hardening adhesive

[0107] As a 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 dosage of monomer components, as well as the type, quantity, combination, and dosage of crosslinking agents, silane coupling agents, and additives, a non-curing adhesive having the desired storage modulus can be obtained (resulting in a second adhesive layer). Examples of non-curing adhesives include, for example, the adhesive described in item C regarding the first and second adhesive layers, the adhesive described in Japanese Patent Application No. 2019-196942 filed by the applicant, and the adhesive described in Japanese Patent Application Publication No. 2016-94569. The descriptions in these applications and publications are incorporated herein by reference.

[0108] E-4. Components of optical parts

[0109] As described above, the adhesive (adhesive composition) constituting the second adhesive layer can be provided as an adhesive sheet. In the manufacture of an image display device, this adhesive sheet can be provided as an assembly of an optical component together with the polarizing plate of an embodiment of the present invention. Therefore, such an assembly of an optical component is also included in embodiments of the present invention. In one embodiment, the assembly of the optical component may further include other polarizing plates (rear-side polarizing plates). That is, in the manufacture of an image display device, the adhesive sheet, the polarizing plate (viewing-side polarizing plate) of an embodiment of the present invention, and the second polarizing plate (rear-side polarizing plate) can be provided as an assembly of an optical component.

[0110] [Example]

[0111] The present invention will now be specifically described through examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows. Furthermore, unless otherwise specified, "parts" and "%" in the examples are based on weight.

[0112] (1) Size of adhesive voids

[0113] The cross-sectional state of the adhesive layer in the through hole of the polarizing plate used in the examples and comparative examples was observed using an optical microscope. The length of the largest defect in the adhesive layer from the outer edge to the inner side of the surface was measured and set as the size L (μm) of the adhesive void.

[0114] (2) Paste offset

[0115] The polarizing plates used in the examples and comparative examples were bonded to glass, treated in an autoclave (50°C / 0.5MPa / 15min), and then subjected to a heating test (85°C, 120h). The through-holes of the tested samples were observed using an optical microscope, and the deformation of the adhesive at the end of the polarizing plate was measured as the displacement of the through-hole. The deformation was measured using an optical microscope (MX61L) manufactured by OLYMPUS. Furthermore, measurements were taken on three test samples, and the maximum value among the three measurements was taken as the offset.

[0116] (3) Bubble Assessment

[0117] After vacuum lamination, the image display device corresponding products obtained in the examples and comparative examples were subjected to autoclaving (50°C / 0.5MPa / 15min) and UV (Ultraviolet) curing (150mW / cm² illuminance). 2(Irradiation dose of 3000 mJ). The sample was then subjected to a heating test (85°C, 24 h), and the state of the bubbles was observed visually or under an optical microscope upon removal. Measurements were performed under n=6 conditions and evaluated according to the following criteria.

[0118] 4: No bubbles were observed in any of the samples.

[0119] 3: Samples with less than half of the samples showed a few air bubbles, but these did not pose any problems for use.

[0120] 2: More than half of the samples showed a few air bubbles, but these did not pose any problems for use.

[0121] 1: All samples contained air bubbles.

[0122] <Manufacturing Example 1: Fabrication of Adhesive Layer (1)>

[0123] A monomer mixture containing 99 parts of butyl acrylate (BA) and 1 part of 4-hydroxybutyl acrylate was added to a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, and cooler. Then, relative to 100 parts of the monomer mixture (solid content), 0.1 parts of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) and 100 parts by weight of ethyl acetate were added as polymerization initiators. While slowly stirring, nitrogen was introduced for nitrogen purging. The liquid temperature in the flask was maintained at approximately 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of acrylic polymer. To obtain an adhesive composition, 0.3 parts of benzoyl peroxide (trade name: Nyper BMT 40SV, manufactured by Nippon Yushi Co., Ltd.) as a crosslinking agent, 0.1 parts of isocyanate crosslinking agent (trade name: Takenate D110N, manufactured by Mitsui Chemicals Co., Ltd.), and 0.2 parts of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 100 parts of the solid content of the obtained acrylic polymer solution.

[0124] Subsequently, a solution of the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (release film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, with the dried adhesive layer having a thickness of 20 μm. The film was then dried at 155°C for 1 minute to form an adhesive layer (1) on the surface of the release film. The creep value of the adhesive layer (1) was 120 μm / hr.

[0125] <Manufacturing Example 2: Fabrication of Adhesive Layer (2)>

[0126] A monomer mixture containing 94.9 parts of butyl acrylate (BA), 5 parts of acrylic acid, and 0.1 parts of 4-hydroxybutyl acrylate was added to a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, and cooler. Then, relative to 100 parts of the monomer mixture (solid content), 0.1 parts by weight of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) and 100 parts by weight of ethyl acetate were added as polymerization initiators. While slowly stirring, nitrogen was introduced for nitrogen purging. The liquid temperature in the flask was maintained at approximately 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of acrylic polymer. To obtain an adhesive composition, 0.1 parts of benzoyl peroxide (trade name: Nyper BMT 40SV, manufactured by Nippon Yushi Co., Ltd.) as a crosslinking agent, 8 parts of isocyanate crosslinking agent (trade name: Coronate L, manufactured by Tosoh Co., Ltd.), and 0.2 parts of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 100 parts of the solid content of the obtained acrylic polymer solution.

[0127] Subsequently, a solution of the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (release film: Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, with the dried adhesive layer having a thickness of 20 μm. The film was then dried at 155°C for 1 minute to form an adhesive layer (2) on the surface of the release film. The creep value of the adhesive layer (2) was 35 μm / hr.

[0128] <Manufacturing Example 3: Preparation of the light-curing adhesive constituting the second adhesive layer>

[0129] 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 isostearate acrylate (ISTA) was added. Then, relative to 100 parts of the monomer mixture (solid component), 0.2 parts of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator, 0.065 parts of α-thioglycerol (TGR) as a chain transfer agent, and 233 parts by weight of ethyl acetate were added. The mixture was stirred at 23°C under a nitrogen atmosphere for 1 hour to undergo nitrogen purging. Then, the reaction was carried out at 56°C for 5 hours, followed by a reaction at 70°C for 3 hours to prepare a solution of an acrylic-based polymer. To the obtained acrylic-based polymer solution, relative to 100 parts of the base polymer, the following additives were added and mixed uniformly to prepare a photocurable adhesive b. The storage modulus of the light-curing adhesive b at 60°C before curing is 4.7 × 10⁻⁶. 4 Pa, the storage modulus at 60°C after hardening is 1.0 × 10 Pa. 5Pa. Furthermore, the gel fraction before curing was 40%, and the gel fraction after curing was 80%.

[0130] (Ingredients added later)

[0131] Dipentaerythritol hexaacrylate as a multifunctional compound (photocuring agent): 2 parts

[0132] Polypropylene glycol diacrylate (trade name: APG400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., polypropylene glycol #400 (n=7) diacrylate, functional group equivalent 268 g / eq), as a multifunctional compound (photocuring agent): 3 parts

[0133] Photopolymerization initiator (trade name: "Irgacure 184", manufactured by BASF): 0.2 parts

[0134] (Preparation of adhesive sheets)

[0135] A photocurable adhesive b was applied to a 75 μm thick polyethylene terephthalate (PET) film (DIAFOIL MRF75 manufactured by Mitsubishi Chemical Corporation) with a silicone release layer on its surface. After removing the solvent by heating at 100°C for 3 minutes, a release PET film of the same type was laminated onto the surface. The laminate obtained in this manner was aged at 25°C for 3 days to obtain an adhesive sheet I with release films temporarily adhered to both sides.

[0136] <Manufacturing Example 4: Fabrication of Polarizing Plate>

[0137] A 30 μm thick polyvinyl alcohol film was dyed and stretched to 3 times its original length while being placed between rollers with different speed ratios at 30°C in a 0.3% iodine solution for 1 minute. Then, it was stretched to a combined stretch ratio of 6 times while being immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes. After washing by immersion in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds, it was dried at 50°C for 4 minutes to obtain a 12 μm thick polarizer. A triacetyl cellulose (TAC) film with a hard coating (2 μm hard coating thickness, 25 μm TAC thickness) as the outer protective layer and a TAC film (25 μm thickness) as the inner protective layer were respectively bonded to both sides of the polarizer. A liquid crystal alignment and curing layer H and a liquid crystal alignment and curing layer Q were sequentially transferred to the inner protective layer side of the polarizer. Thus, the polarizing plate (1) is manufactured. Furthermore, the liquid crystal alignment and curing layer H and the liquid crystal alignment and curing layer Q are manufactured in the following manner.

[0138] A liquid crystal composition (coating solution) was prepared by dissolving 10g of a polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) exhibiting a nematic liquid crystal phase and 3g of a photopolymerization initiator (manufactured by BASF: trade name "Irgacure 907") relative to the polymerizable liquid crystal compound in 40g of toluene.

[0139] [Chemistry 1]

[0140]

[0141] Alignment treatment was performed by rubbing the surface of a polyethylene terephthalate (PET) film (38 μm thick) with a rubbing cloth. The alignment direction was set to be 15° relative to the absorption axis of the polarizer when viewed from the viewing side after being attached to the polarizer. The liquid crystal coating solution was applied to the alignment-treated surface using a rod coater and heated and dried at 90°C for 2 minutes to align the liquid crystal compound. The liquid crystal layer formed in this manner was irradiated with a metal halide lamp at 1 mJ / cm². 2 The liquid crystal layer is hardened by light, thereby forming a liquid crystal alignment and curing layer H on the PET film. The thickness of the liquid crystal alignment and curing layer H is 2.5 μm, and the in-plane phase difference Re(550) is 270 nm. Furthermore, the liquid crystal alignment and curing layer H has a refractive index distribution of nx > ny = nz. Except for changing the coating thickness and setting the alignment processing direction to be 75° relative to the absorption axis of the polarizer when viewed from the viewing side, a liquid crystal alignment and curing layer Q is formed on the PET film in the same manner as described above. The thickness of the liquid crystal alignment and curing layer Q is 1.5 μm, and the in-plane phase difference Re(550) is 140 nm. Furthermore, the liquid crystal alignment and curing layer Q has a refractive index distribution of nx > ny = nz.

[0142] <Example 5: Fabrication of a Polarizing Plate>

[0143] A 30 μm thick polyvinyl alcohol film was dyed and stretched to 3 times its original length by rolling between rollers with different speed ratios at 30°C in a 0.3% iodine solution for 1 minute. Then, it was stretched to 6 times its original length by immersing it in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes. Subsequently, it was washed by immersing it in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds and then dried at 50°C for 4 minutes to obtain a polarizer with a thickness of 12 μm. A triacetyl cellulose (TAC) film with a hard coating (hard coating thickness of 2 μm and TAC thickness of 25 μm) as the outer protective layer and an acrylic resin film (thickness of 20 μm) as the inner protective layer were respectively bonded to both sides of the polarizer to produce a polarizing plate (2).

[0144] <Manufacturing Example 6: Fabrication of Polarizing Plate>

[0145] 1. Fabrication of polarizers

[0146] As the thermoplastic resin substrate, an amorphous polyethylene terephthalate (PET) copolymer of isophthalic acid (100 μm) with a strip shape, a water absorption rate of 0.75%, and a Tg of approximately 75 °C is used. One side of the resin substrate is subjected to corona treatment.

[0147] Add 13 parts by weight of potassium iodide to 100 parts by weight of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 moles) and acetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") in a ratio of 9:1, and dissolve the mixture in water to prepare a PVA aqueous solution (coating solution).

[0148] The PVA aqueous solution is coated onto the corona-treated surface of the resin substrate and dried at 60°C to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate.

[0149] In an oven at 130°C, the obtained laminate is subjected to free-end uniaxial stretching in the longitudinal direction (length direction) between rollers with different circumferential speeds until it is stretched to 2.4 times (air-assisted stretching process).

[0150] The laminate was then immersed in an insoluble bath (an aqueous solution of boric acid prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a temperature of 40°C for 30 seconds (insoluble treatment).

[0151] Subsequently, the polarizing film is immersed in a dyeing bath at a liquid temperature of 30°C (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a weight ratio of 1:7 relative to 100 parts by weight of water) for 60 seconds while adjusting the concentration, so that the monomer transmittance (Ts) of the final polarizing film reaches a specific value (dyeing treatment).

[0152] Then, it is immersed in a crosslinking bath at a liquid temperature of 40°C (an aqueous solution of boric acid prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid relative to 100 parts by weight of water) for 30 seconds (crosslinking treatment).

[0153] Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide 5.0 wt%) at a liquid temperature of 70°C, it is uniaxially stretched (water stretching treatment) in the longitudinal direction (length direction) between rollers with different circumferential speeds, with a total elongation ratio of 5.5 times.

[0154] Then, the laminate is immersed in a washing bath at a temperature of 20°C (an aqueous solution of 4 parts by weight of potassium iodide mixed with 100 parts by weight of water) (washing treatment).

[0155] Then, while drying in an oven maintained at 90°C, it is simultaneously brought into contact with a heating roller made of SUS (Steel Use Stainless, Japanese standard) with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The width-direction shrinkage rate of the laminate after the drying shrinkage treatment is 5.2%.

[0156] Thus, a polarizer with a thickness of 5 μm is formed on the resin substrate.

[0157] 2. Fabrication of polarizing plates

[0158] An HC-TAC film is bonded to the polarizer surface of the obtained resin substrate / polarizer laminate using a UV-curable adhesive. Specifically, the adhesive is applied with a curable thickness of 1.0 μm and bonded using a roller press. Then, UV light is irradiated from the HC-TAC film side to cure the adhesive. Furthermore, an HC-TAC film with a 7 μm thick hard coating (HC) layer formed on a 25 μm thick triacetyl cellulose (TAC) film is bonded with the TAC film on the polarizer side. Next, the resin substrate is peeled off, and a 20 μm thick TAC film is bonded to the peeled surface in the same manner. Thus, a polarizer plate (3) is fabricated.

[0159] <Example 1>

[0160] 1. Formation of through holes

[0161] An adhesive layer (1) obtained in Manufacturing Example 1 is formed on the surface of the liquid crystal alignment and curing layer Q of the polarizing plate (1) obtained in Manufacturing Example 4, thus creating a polarizing plate with an adhesive layer. The polarizing plate with the adhesive layer is punched to a size of 145 mm in length and 68 mm in width. The punching is performed at a 135° clockwise angle relative to the long side direction of the polarizer's absorption axis. Furthermore, a through hole with a diameter of 3.9 mm is formed at the upper right corner of the punched polarizing plate with the adhesive layer by an end mill. Thus, a polarizing plate with an adhesive layer is manufactured as described above. Figure 1A The polarizing plate shown is a polarizing plate with an adhesive layer. The |b1-b2| of the obtained polarizing plate is 0 mm. Also, the size L of the adhesive voids is 90 μm. This polarizing plate was used for the evaluation described in (2). The results are shown in Table 1.

[0162] 2. Production of corresponding products for image display devices

[0163] The polarizing plate with the adhesive layer obtained in step 1 is bonded to one side of the glass plate (corresponding to the image display unit) via the adhesive layer. Then, one release film of the adhesive sheet I obtained in Manufacturing Example 3 is peeled off and bonded to the cover glass (manufactured by Matsunami Glass Co., Ltd., 0.8 mm thick) using a roller laminator. Next, another release film of the adhesive sheet I is peeled off and vacuum-laminated to ensure close contact with the surface of the polarizing plate with the adhesive layer, and the through holes are filled with the adhesive sheet. The vacuum lamination conditions are as follows: heated lamination at 0.2 MPa and 60°C (standby time 90 seconds), followed by vacuum lamination at 100 Pa for 10 seconds. Furthermore, a metal halide lamp (300 mW / cm²) is used from the cover glass side. 2 The cumulative light intensity of the irradiation was 3000 mJ / cm². 2 The photocurable adhesive is cured by ultraviolet light. Then, it is subjected to autoclave treatment (50°C / 0.5MPa / 15min). Thus, an image display device prototype is produced. The obtained image display device prototype is subjected to the bubble evaluation described in (3). The results are shown in Table 1.

[0164] <Example 2>

[0165] Except that the through-hole is formed at the end in the long side direction and the center in the short side direction, the polarizing plate (polarizing plate with adhesive layer) and the corresponding image display device are manufactured in the same manner as in Example 1. The |b1-b2| of the obtained polarizing plate is 41 mm. Also, the size L of the adhesive void is 90 μm. The obtained polarizing plate and the corresponding image display device are evaluated in the same manner as in Example 1. The results are shown in Table 1. Furthermore, in Table 1, the end in the long side direction and the center in the short side direction are simply referred to as "center".

[0166] <Examples 3-7 and Comparative Examples 1-4>

[0167] Except for the type and size of the polarizing plate, the type of adhesive layer, and the location of the through hole as shown in Table 1, the polarizing plate (polarizing plate with adhesive layer) and the corresponding image display device are manufactured in the same manner as in Example 1. Furthermore, the size L of the adhesive void is adjusted during the end milling process of forming the through hole by changing the feed rate or rotation speed and cutting amount of the drill. Here, Examples 4 and 6 are similar to... Figure 1A Corresponding to the shape shown, Example 7 and Figure 1B Corresponding to the forms shown, Examples 3 and 5 are... Figure 1C The shapes shown correspond to those in Example 1. The obtained polarizing plates and corresponding image display devices were subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0168] [Table 1]

[0169]

[0170] As shown in Table 1, the amount of paste shift in the through-hole portion of the polarizing plate in the embodiment of the present invention after the heating test is significantly smaller than that in the comparative example, and the delayed bubbles are suppressed.

[0171] [Industry availability]

[0172] The polarizing plate of the present invention is suitable for use in image display devices, and is particularly suitable for use in image display devices with camera units, such as smartphones, tablet PCs or smartwatches.

[0173] Explanation of reference numerals in the attached figures

[0174] 11: Polarizing filter

[0175] 12: Outer protective layer

[0176] 13: Inner protective layer

[0177] 20: Adhesive layer

[0178] 30: Through hole

[0179] 100:Polarizing plate

Claims

1. A polarizing plate comprising: a polarizer; a protective layer disposed on at least one side of the polarizer; and an adhesive layer; and Formed with through holes, The thickness of this polarizer is less than 15 μm. |b1-b2| is less than 45 mm. Here, b1 is the distance from the center of the through hole to one end of the polarizer along the absorption axis of the polarizer, and b2 is the distance from the center of the through hole to the other end of the polarizer along the absorption axis of the polarizer.

2. The polarizing plate as claimed in claim 1, having a rectangular shape, wherein when viewed from the viewing side, the absorption axis of the polarizer is 135° clockwise from the long side, and the through hole is formed at the upper right corner.

3. The polarizing plate as claimed in claim 1, having a rectangular shape, wherein when viewed from the viewing side, the absorption axis of the polarizer is oriented at a 45° angle clockwise from the long side, and the through hole is formed at the upper left corner.

4. The polarizing plate as claimed in claim 1, having a rectangular shape, wherein the absorption axis of the polarizer is in the direction of the short side, and when viewed from above, the through hole is formed at the end of the long side and at the center of the short side.

5. The polarizing plate according to any one of claims 1 to 4, wherein the thickness of the polarizer is 8 μm or less.

6. The polarizing plate according to any one of claims 1 to 4, wherein the creep value of the adhesive layer is less than 140 μm / hr. The creep value was determined by the following sequence: the adhesive forming the adhesive layer was attached to the support plate; the support plate with the adhesive attached was fixed, and in this state, a load of 500 g was applied downward in the vertical direction. The amount of displacement of the adhesive from the support plate after 1 hour of applying the load was measured, and this displacement was taken as the creep value.

7. An image display device, comprising: an image display unit and a polarizing plate as described in any one of claims 1 to 6; and The polarizing plate is attached to the image display unit via the adhesive layer.

8. A polarizing plate with a cover glass, comprising: a polarizer; a protective layer disposed on at least one side of the polarizer; an adhesive layer; another adhesive layer disposed on the side of the polarizer opposite to the adhesive layer; and a cover glass bonded thereto via the other adhesive layer; and A through-hole is formed, which is filled with adhesive constituting the other adhesive layer. The thickness of this polarizer is less than 15 μm. |b1-b2| is less than 45 mm. Here, b1 is the distance from the center of the through hole to one end of the polarizer along the absorption axis of the polarizer, and b2 is the distance from the center of the through hole to the other end of the polarizer along the absorption axis of the polarizer.

Images