JP2022053732A - Polarizing plate and picture display unit - Google Patents

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

The present invention relates to a polarizing plate and an image display device. More specifically, the present invention relates to a polarizing plate having a pressure-sensitive adhesive layer and having through holes formed therein, and an image display device including such a polarizing plate.

Polarizing plates are widely used in image display devices such as mobile phones and notebook personal computers in order to realize image display and / or enhance the performance of the image display. In recent years, it has been desired to use a polarizing plate in an image display device equipped with a camera, a smart watch, an instrument panel of an automobile, and the like, and a through hole may be formed in the polarizing plate. However, the polarizing plate having a through hole has a problem that the polarizing plate is displaced (substantially, the adhesive layer is displaced) at the through hole portion in a high temperature environment.

By the way, in order to impart surface hardness and impact resistance to the image display device, a cover glass may be laminated on the outermost surface of the image display device. When the cover glass is laminated on an image display device including a polarizing plate having a through hole, the through hole is typically filled with an adhesive for laminating the cover glass. However, in an image display device in which the through holes are filled with an adhesive, bubbles may be generated in the filled portion (through hole portion) due to heat treatment or the like in the manufacturing process.

International Publication No. 2017/047510 Japanese Unexamined Patent Publication No. 2016-0946569

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have a small displacement in a through-hole portion even in a high temperature environment, and to have an adhesive for laminating a cover glass in an image display device. It is an object of the present invention to provide a polarizing plate capable of significantly suppressing air bubbles in a through-hole portion when the through-hole is filled with an agent.

The polarizing plate of the present invention has a polarizing element, a protective layer arranged on at least one side of the polarizing element, and an adhesive layer, and a through hole is formed, and the thickness of the polarizing element is increased. It is 15 μm or less, and | b ₁ − b ₂ | is 45 mm or less. Here, b ₁ is the distance from the center of the through hole to one end of the polarizing plate in the absorption axis direction of the substituent, and b ₂ 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 splitter. The distance to the edge.
In one embodiment, the polarizing plate has a rectangular shape, the absorption axis direction of the polarizing element is 135 ° clockwise from the long side direction when viewed from the visual side, and the through hole is in the right corner. Is formed in. In another embodiment, the polarizing plate has a rectangular shape, the absorption axis direction of the polarizing element is 45 ° clockwise from the long side when viewed from the visual side, and the through hole is in the left corner. It is formed. In yet another embodiment, the polarizing plate has a rectangular shape, the absorption axis direction of the polarizing element is the short side direction, and the through hole is the end portion and the short side in the long side direction when viewed in a plan view. It is formed in the center of the direction.
In one embodiment, the thickness of the stator is 8 μm or less.
In one embodiment, the creep value of the pressure-sensitive 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 above-mentioned polarizing plate, and the polarizing plate is attached to the image display cell via the above-mentioned pressure-sensitive adhesive layer.

According to the embodiment of the present invention, the polarizing plate has a through hole, the deviation in the through hole portion is small even in a high temperature environment, and the through hole is an adhesive for laminating the cover glass in the image display device. It is possible to realize a polarizing plate in which bubbles in the through-hole portion can be remarkably suppressed when filled with.

It is a schematic plan view explaining the formation position of the through hole in the polarizing plate by one Embodiment of this invention. It is a schematic plan view explaining the formation position of the through hole in the polarizing plate by another embodiment of this invention. It is a schematic plan view explaining the formation position of the through hole in the polarizing plate by still another embodiment of this invention. It is schematic cross-sectional view of the through hole part of the polarizing plate by embodiment of this invention. It is an enlarged sectional view of the main part explaining the deviation in the through hole part in the polarizing plate by embodiment of this invention.

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. The drawings are schematically shown for easy viewing, and the ratios of length, width, thickness, etc., angles, etc. in the drawings are different from the actual ones.

A. Overall Configuration of the Polarizer FIG. 1A is a schematic plan view illustrating the position of formation of through holes in the polarizing plate according to one embodiment of the present invention; FIG. 1B is a penetration in the polarizing plate according to another embodiment of the present invention. FIG. 1C is a schematic plan view illustrating the position of formation of the through hole in the polarizing plate according to still another embodiment of the present invention; FIG. 2 is a schematic plan view illustrating the position of formation of the through hole in the polarizing plate according to still another embodiment of the present invention. It is a schematic cross-sectional view of a through hole portion. The polarizing plate according to the embodiment of the present invention (polarizing plate 100, 101, 102 in the illustrated example) may be referred to as a polarizing element 11 and a protective layer arranged on one side of the polarizing element 11 (hereinafter, referred to as an outer protective layer). There is 12), a protective layer (hereinafter, may be referred to as an inner protective layer) 13 arranged on the other side of the polarizing element 11, and a pressure-sensitive adhesive layer 20. The pressure-sensitive adhesive layer 20 is used to attach the polarizing plate 100 to the image display cell. Either the outer protective layer 12 or the inner protective layer 13 may be omitted depending on the purpose, the desired configuration, and the like.

A through hole 30 is formed in the polarizing plate. By forming the through hole, for example, when the image display device has a built-in camera, it is possible to prevent an adverse effect on the camera performance. The through hole can be formed by various methods such as laser machining, cutting with an end mill, punching with a Thomson blade or a Pinnacle (registered trademark) blade. The polarizing plate typically has a rectangular shape. In the present specification, the term "rectangular shape" includes a shape including a deformed portion such as an R shape in which each vertex is chamfered as shown in FIGS. 1A to 1C. Although not shown, a plurality of through holes may be provided. Further, as the plan view shape of the through hole, any appropriate shape may be adopted depending on the purpose. Specific examples of the plan view shape include a circle, an ellipse, a square, a rectangle, and a combination thereof (for example, a rectangle having an arcuate end) as shown in the illustrated example. Further, a deformed portion (for example, a U-shaped notch, a V-shaped notch) may be provided together with the through hole. When a through hole is formed in the polarizing plate, the present inventors may refer to the displacement of the polarizing plate at the through hole portion (substantially, the displacement of the pressure-sensitive adhesive layer: hereinafter referred to as glue displacement) in a high temperature environment. (There is), and as a result, a new problem that light leakage may occur in the through-hole portion is discovered, and the problem is solved by adopting a predetermined configuration (described later) of the embodiment of the present invention. Settled. That is, the present invention solves a new problem that has not been known until now, and the effect obtained by this is unexpectedly excellent. Furthermore, the present inventors have found that by adopting a predetermined configuration (described later) of the embodiment of the present invention, bubbles called delay bubbles can be remarkably suppressed. The details of the delay bubble are as follows. A cover glass may be laminated on the outermost surface of the image display device in order to impart surface hardness and impact resistance to the image display device. When the cover glass is laminated on an image display device including a polarizing plate having a through hole, the through hole is typically filled with an adhesive for laminating the cover glass. Such filling is typically performed by laminating a laminate of a cover glass and an adhesive sheet to a polarizing plate by vacuum laminating. Immediately after vacuum laminating, there are often no recognizable bubbles in the filled portion, but bubbles may be generated in the subsequent heating durability test of the image display device. Such bubbles can typically be generated by the contraction stress of the polarizing plate applied to the filled portion. Such bubbles are called delay bubbles. The delay bubble is not a fine one, but a large one that occupies a certain percentage or more of the planar viewing area of the through hole, and from the viewpoint of appearance and the camera performance of the camera unit provided at the position corresponding to the through hole. It is unacceptable. Therefore, by suppressing the delay bubble, the commercial value of the image display device can be significantly improved.

In the embodiment of the present invention, the thickness of the polarizing element is 15 μm or less, preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less, particularly preferably 6 μm or less, and particularly preferably. It is preferably 5 μm or less. The thickness of the splitter can be, for example, 1 μm or more, and can be, for example, 2 μm or more. By setting the thickness of the splitter in such a range, it is possible to suppress the thermal shrinkage of the splitter itself. As a result, it is possible to suppress deformation (resulting in glue slippage) of the pressure-sensitive adhesive layer that can follow the heat shrinkage of the polarizing element.

Further, in the embodiment of the present invention, | b ₁ -b ₂ | is 45 mm or less, preferably 30 mm or less, more preferably 20 mm or less, still more preferably 10 mm or less, and particularly preferably 5 mm. It is as follows. The smaller the | b ₁ − b ₂ |, the more preferable, and the most preferable is 0 (zero). When | b ₁ − b ₂ | is in such a range, the glue slippage in the through hole portion in the high temperature environment can be reduced, and the delay bubble can be suppressed. On the other hand, | a1 _{- a2} | does not substantially contribute to the suppression of glue slippage at the through-hole portion and the suppression of delay bubbles. That is, even if | a ₁ − a ₂ | is changed, glue misalignment and delay bubble are not suppressed. Here, b ₁ is the distance from the center of the through hole to one end of the polarizing plate in the absorption axis direction of the substituent, and b ₂ 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 splitter. The distance to the end, a1 is the distance from the center of the through hole to _one end of the polarizing plate in the direction orthogonal to the absorption axis direction of the substituent, and _a2 is orthogonal to the absorption axis direction of the polarizing element. The distance from the center of the through hole to the other end of the polarizing plate in the direction. That is, by optimizing the direction of the absorption axis of the polarizing element with respect to the position of the through hole, both glue slippage and delay bubble can be suppressed.

With reference to FIGS. _1A to _1C , the relationship between a1, _a2 , b1 and _b2 and the formation position of the through hole will be specifically described. In FIG. 1A, the polarizing plate is rectangular, and the absorption axis direction A of the polarizing element is 135 ° clockwise with respect to the long side direction when viewed from the visual recognition side (opposite side of the adhesive layer) of the image display device. A form is shown. In this embodiment, when | b1 _{- b2} | is optimized, the through hole 30 is on a straight line extending in a direction orthogonal to the absorption axis direction A from the upper right corner when the polarizing plate is viewed in a plan view from the visual recognition side (FIG. In _1A , if it is formed at an arbitrary position on the straight line indicating the distances a1 and _a2 ), both the glue slippage and the delay bubble can be suppressed. On the other hand, by adjusting | a1 _{- a2} | to minimize the influence on the image display, the through hole 30 can be preferably formed in the upper right corner. FIG. 1B shows a form in which the polarizing plate is rectangular and the absorption axis direction A of the polarizing element is 45 ° clockwise with respect to the long side direction when viewed from the visual side of the image display device. Also in this form, by optimizing | b1 _{- b2} |, both glue misalignment and delay bubble can be suppressed, and | a1 _{- a2} | is adjusted to minimize the effect on the image display. can do. As a result, in this form, the through hole 30 can be preferably formed in the upper left corner. FIG. 1C shows a form in which the polarizing plate is rectangular and the absorption axis direction A of the polarizing element is the short side direction (orthogonal to the long side direction). Also in this form, by optimizing | b1 _{- b2} |, both glue misalignment and delay bubble can be suppressed, and | a1 _{- a2} | is adjusted to minimize the effect on the image display. can do. As a result, in this form, the through hole 30 can be formed preferably at the end portion in the long side direction and the central portion in the short side direction. As is clear from the above, according to the embodiment of the present invention, regardless of the planar shape of the polarizing plate (for example, even if it has a special planar shape), | b1 _- b. By optimizing ₂ |, it is possible to determine the relationship between the position of the through hole where the glue slippage and the delay bubble can be suppressed and the absorption axis direction. Further, by adjusting | a1 _{- a2} |, the influence of the through hole on the image display can be minimized.

In one embodiment, as shown in FIG. 3, the polarizing plate 100 is in a state where the polarizing plate 100 is attached to a glass plate (which can correspond to a substrate of an image display cell) 120 via an adhesive layer 20. The displacement amount (glue displacement amount) D in the through hole 30 portion after being subjected to the heating test at 85 ° C. and 120 hours is preferably 150 μm or less, more preferably 120 μm or less, still more preferably 100 μm or less. It is particularly preferably 80 μm or less, and particularly preferably 50 μm or less. The smaller the deviation amount D, the more preferable, and the lower limit of the glue deviation amount D is, for example, 10 μm, and may be, for example, 20 μm. The amount of glue misalignment D refers to the maximum portion of the polarizing plate that moves away from the through-hole portion when viewed in cross section. The reference for the through-hole portion may typically be the lower end of the pressure-sensitive adhesive layer. That is, when the polarizing plate shifts mainly due to the shrinkage of the polarizing element 11 (to the right in the illustrated example), the pressure-sensitive adhesive layer 20 stays on the adhered glass plate 120, so that the shift is recognized in the through-hole portion. It will be. As shown in FIG. 3, the polarizing plate is typically displaced to the side away from the through hole in the through hole portion (right side of FIG. 3), and the opposite portion is displaced so as to protrude into the through hole (FIG. 3). 3 left side). As described above, according to the embodiment of the present invention, it is possible to solve the newly discovered problem of glue misalignment in the through hole portion in a high temperature environment, and specifically, the glue after a predetermined heating test. The deviation amount D can be set to the above range.

In one embodiment, in the polarizing plate, the end face of the pressure-sensitive adhesive layer 20 is more surface than the end face of the polarizing plate (substantially, the polarizing element 11 or the inner protective layer 13 if present) in the through hole 30 portion. Adhesive voids formed located inward in the direction may be formed. The size of the pressure-sensitive 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 particularly preferably 80 μm or less. The lower limit of the size of the pressure-sensitive adhesive gap may be, for example, 10 μm. In the present specification, the "size of the pressure-sensitive adhesive gap" is the maximum length from the end face of the polarizing plate (substantially the polarizing element 11 or the inner protective layer 13 if present) to the end face of the pressure-sensitive adhesive layer 20. Say.

In the embodiment of the present invention, the dimensional shrinkage of the polarizing plate after the heating test is preferably 1.0% or less, more preferably 0.6% or less, still more preferably 0.3% or less. Is. The smaller the dimensional shrinkage, the more preferable, and the lower limit of the dimensional shrinkage can be, for example, 0.01%. The dimensional shrinkage is calculated by the following formula. The dimensional shrinkage rate is the dimensional shrinkage rate of the entire polarizing plate attached to the glass plate, and when the polarizing plate further has an optical functional layer (for example, a retardation layer, a reflective polarizing element) as described later, the dimensional shrinkage rate is a dimensional shrinkage rate. It means the dimensional shrinkage rate of the entire polarizing plate including the optical functional layer. The "dimension" in the following formula is the dimension in the absorption axis direction of the polarizing plate (substantially, the polarizing element).
Dimension shrinkage rate (%) = {(dimension before heating test-dimension after heating test) / dimension before heating test} x 100

The diameter R of the through hole 30 is preferably 10 mm or less, more preferably 8 mm or less, and further preferably 5 mm or less. The lower limit of the diameter of the through hole is, for example, 1.5 mm and can be, for example, 2 mm. The ratio D / R of the amount of glue misalignment D to the diameter R of the through hole is preferably 15% or less, more preferably 10% or less, still more preferably 6% or less, and particularly preferably 5% or less. be. On the other hand, the smaller the lower limit of D / R, the more preferable. According to the embodiment of the present invention, since the amount of glue misalignment D is very small as described above, the D / R can be set in such a range even if the diameter of the through hole is reduced. Therefore, even if the diameter of the through hole is reduced, the adverse effect on the 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 unit is a non-display area.

The polarizing plate according to the embodiment of the present invention may be used as a viewing side polarizing plate or a back side polarizing plate. Further, the polarizing plate according to the embodiment of the present invention may further have any suitable optical functional layer depending on the intended purpose. Examples of the optical functional layer include a retardation layer, a conductive layer for a touch panel, and a reflective polarizing element.

In one embodiment, a retardation layer may be provided between the inner protective layer 13 and the pressure-sensitive adhesive layer 20. The retardation layer may be composed of a single layer or may have a laminated structure. When the retardation layer is composed of a single layer, the retardation layer can typically function as a λ / 4 plate. In this case, the in-plane retardation Re (550) of the retardation layer is preferably 100 nm to 200 nm, more preferably 120 nm to 170 nm, and further preferably 130 nm to 150 nm. The angle formed by the absorption axis of the splitter and the slow axis of the retardation layer is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably 44 ° to 46 °. .. The retardation layer preferably exhibits a reverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. In this case, Re (450) / Re (550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. The retardation layer may be a stretched film of a resin film or an orientation-solidified layer of a liquid crystal compound. When the retardation layer is made of a resin film, the retardation layer may also serve as an inner protective layer. The retardation layer made of a stretched film of a resin film is described in, for example, JP-A-2017-54093 and JP-A-2018-60014. Specific examples of the liquid crystal compound and details of the method for forming the oriented solidified layer are described in, for example, Japanese Patent Application Laid-Open No. 2006-163343. The description of these publications is incorporated herein by reference. In the present specification, "Re (λ)" is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained 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 in which the in-plane refractive index is maximized (that is, the slow phase axis direction), and ny is the refractive index in the in-plane direction orthogonal to the slow phase axis (that is, the phase advance axis direction). be.

When the retardation layer has a laminated structure, the retardation layer typically has an H layer and a Q layer in order from the polarizing plate 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 further preferably 260 nm to 280 nm. The angle formed by the absorption axis of the splitter 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 further preferably 130 nm to 150 nm. The angle formed by the absorption axis of the splitter 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 formed by the slow axis of the H layer and the absorption axis of the stator and the angle formed by the slow axis of the Q layer and the absorption axis of the splitter The reverse may be true. Each of the H layer and the Q layer may be a stretched film of a resin film or an oriented solidified layer of a liquid crystal compound.

In one embodiment, a touch panel conductive layer may be provided on the opposite side of the inner protective layer 13 (if present, a retardation layer) to the polarizing element. With such a configuration, the polarizing plate 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 polarizing plate. The polarizing plate of this embodiment is typically a viewing-side polarizing plate.

In one embodiment, a reflective polarizing element may be provided on the opposite side of the outer protective layer 12 from the polarizing element. The reflective polarizing element may also serve as an outer protective layer. The polarizing plate of this embodiment is typically a backside polarizing plate. Details of the reflective classifier are described in, for example, Japanese Patent Application Laid-Open No. 9-507308 and Japanese Patent Application Laid-Open No. 2013-235259. The description of these publications is incorporated herein by reference.

When the polarizing plate according to the embodiment of the present invention is rectangular, the aspect ratio is preferably 1.3 to 2.5. In this case, the size of the polarizing plate is, for example, 145 mm to 155 mm in length and 65 mm to 75 mm in width, or 230 mm to 240 mm in length 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 for a smartphone or a tablet-type PC. The smartphone size may be, for example, 120 mm to 200 mm in length and 30 mm to 120 mm in width.

Hereinafter, the polarizing element, the protective layer, and the pressure-sensitive adhesive layer constituting the polarizing plate will be specifically described.

B. Polarizing plate B-1. Polarizer The splitter is typically composed of a resin film containing a dichroic substance. As the resin film, any suitable resin film that can be used as a polarizing element can be adopted. The resin film is typically a polyvinyl alcohol-based resin (hereinafter referred to as “PVA-based resin”) film. The resin film may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizing element composed of a single-layer resin film include those obtained by subjecting a PVA-based resin film to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). The dyeing with iodine is performed, for example, by immersing a PVA-based resin film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Further, it may be dyed after being stretched. If necessary, the PVA-based resin film is subjected to a swelling treatment, a crosslinking treatment, a cleaning treatment, a drying treatment and the like. For example, by immersing the PVA-based resin film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based resin film, but also to swell and dye the PVA-based resin film. It is possible to prevent unevenness and the like.

Specific examples of the polarizing element obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizing element obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizing element obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a stator. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further comprise, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of the method for producing such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The description of these patent documents is incorporated herein by reference.

The thickness of the polarizing element is as described in the above item A.

The splitter preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the substituent 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 polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

B-2. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for the stator. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. , Polyester-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

Even if the outer protective layer 12 (particularly when the polarizing plate is a viewing-side polarizing plate) is subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-sticking treatment, anti-glare treatment, etc., if necessary. good. Further / or, if necessary, the outer protective layer 12 is provided with a process for improving visibility when visually recognizing through polarized sunglasses (typically, by imparting a (elliptical) circular polarization function, ultra-high order. (Giving a phase difference) may be applied. By performing such processing, excellent visibility can be realized even when the display screen is visually recognized through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate can also be suitably applied to an image display device that can be used outdoors.

The inner protective layer is preferably optically isotropic. As used herein, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. say. Here, "Rth (λ)" is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained 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.

Any suitable thickness can be adopted as the thickness of the protective layer. The thickness of the protective layer is, for example, 10 μm to 50 μm, preferably 20 μm to 40 μm. When the surface treatment is applied, the thickness of the protective layer is the thickness including the thickness of the surface treatment layer.

C. Adhesive layer The adhesive layer 20 is used to attach the polarizing plate to the image display cell as described above. The pressure-sensitive adhesive layer may be typically composed of an acrylic pressure-sensitive adhesive (acrylic pressure-sensitive adhesive composition). The acrylic pressure-sensitive adhesive composition typically contains a (meth) acrylic polymer as a main component. The (meth) acrylic polymer can be contained in the pressure-sensitive adhesive composition in a proportion of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more in the solid content of the pressure-sensitive adhesive composition. The (meth) acrylic polymer contains an alkyl (meth) acrylate as a main component as a monomer unit. In addition, (meth) acrylate means acrylate and / or methacrylate. The alkyl (meth) acrylate may be contained in a proportion of preferably 80% by weight or more, more preferably 90% by weight or more, in the monomer component forming the (meth) acrylic polymer. Examples of the alkyl group of the alkyl (meth) acrylate include a linear or branched alkyl group having 1 to 18 carbon atoms. The average number of carbon atoms of the alkyl group is preferably 3 to 9, and more preferably 3 to 6. The preferred alkyl (meth) acrylate is butyl acrylate. As the monomer (copolymerization monomer) constituting the (meth) acrylic polymer, in addition to the alkyl (meth) acrylate, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an aromatic ring-containing (meth) acrylate, and a complex Examples include ring-containing vinyl-based monomers. Representative examples of the copolymerized monomer include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic pressure-sensitive adhesive composition may preferably contain a silane coupling agent and / or a cross-linking agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Examples of the cross-linking agent include isocyanate-based cross-linking agents and peroxide-based cross-linking agents. Further, the acrylic pressure-sensitive adhesive composition may contain an antioxidant and / or a conductive agent. The thickness of the pressure-sensitive adhesive layer is, for example, 50 μm or less, preferably 22 μm or less, and more preferably 10 μm to 22 μm as described above. Details of the pressure-sensitive adhesive layer or the acrylic pressure-sensitive adhesive composition are, for example, JP-A-2006-183022, JP-A-2015-199942, JP-A-2018-053114, JP-A-2016-190996, International Publication. No. 2018/008712, the description of these publications is incorporated herein by reference.

The creep value of the pressure-sensitive 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. As used herein, the term "creep value" means a creep value at 85 ° C. The creep value can be measured, for example, by the following procedure: the adhesive constituting the adhesive layer is attached to the support plate. With the support plate to which the adhesive is attached fixed, a load of 500 g 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 the amount of displacement is defined as the creep value (μm / hr).

The storage elastic modulus G _2'at −40 ° C. of the pressure-sensitive adhesive layer is preferably 1.0 × 10 ⁵ (Pa) or more, more preferably 1.0 × 10 ⁶ (Pa) or more, and further preferably 1.0 × 10 6 (Pa) or more. It is 1.0 × 10 ⁷ (Pa) or more, and particularly preferably 1.0 × 10 ⁸ (Pa) or more. The storage elastic modulus G _2'can be, for example, 1.0 × ¹⁰⁹ (Pa) or less. The storage elastic modulus _G3'at 85 ° C. of the pressure-sensitive adhesive layer is preferably 1.0 × 105 (Pa) or more, more preferably 3.0 × ¹⁰⁵ (Pa) or more, and further preferably ⁵ It is 0.0 × 10 ⁵ (Pa) or more. The storage modulus _G3'can be, for example, 1.0 × ¹⁰⁶ (Pa) or less.

D. Image Display Device The polarizing plate according to the embodiment of the present invention can be applied to an image display device. Therefore, an image display device is also included in the embodiment of the present invention. The image display device includes an image display cell and a polarizing plate. The polarizing plate is a polarizing plate according to the embodiment of the present invention according to the above items A to C. The polarizing plate is attached to the image display cell via the pressure-sensitive adhesive layer. Examples of the image display device include a liquid crystal display device, an organic electroluminescence (EL) display device, and a quantum dot display device.

E. Polarizing plate with cover glass When the polarizing plate according to the embodiment of the present invention is applied to the visual recognition side of the image display device, the cover glass provides another pressure-sensitive adhesive layer (hereinafter, may be referred to as a second pressure-sensitive adhesive layer). It may be attached to the polarizing plate via the plate. Therefore, an embodiment of the present invention includes a polarizing plate with a cover glass layer. Further, the polarizing plate according to the embodiment of the present invention may be provided in a form in which a separator is temporarily attached instead of the cover glass. In this case, the separator is peeled off and removed when the image display device is manufactured, and the cover glass is attached via the exposed second adhesive layer. In either case, the through holes can typically be filled with the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer. Hereinafter, the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer will be described.

The pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer typically has a storage elastic modulus at 60 ° C. of 1.0 × 10 ⁴ Pa to 1.0 when the second pressure-sensitive adhesive layer is laminated on the polarizing plate. × 10 ⁵ Pa. As the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer, any suitable pressure-sensitive adhesive can be used as long as it has such a storage elastic modulus at the time of laminating. Specifically, the pressure-sensitive adhesive may be a photocurable pressure-sensitive adhesive or a non-curable pressure-sensitive adhesive. In the present specification, the "photocurable pressure-sensitive adhesive" refers to a pressure-sensitive adhesive whose cross-linking reaction proceeds by irradiation with light. Therefore, the photocurable pressure-sensitive adhesive is soft and has excellent deformability at the time of laminating, and can be imparted with desired properties (for example, storage elastic modulus) as the pressure-sensitive adhesive layer by irradiating with light after laminating. As a result, the photocurable pressure-sensitive adhesive is extremely excellent in filling property of the deformed portion, and the thickness of the second pressure-sensitive adhesive layer (as a result, the image display device) can be reduced. Further, even when a thick frame printing layer is formed on the cover glass, for example, good adhesiveness can be ensured. The "non-curable pressure-sensitive adhesive" refers to a pressure-sensitive adhesive in which the cross-linking reaction is substantially completed and the cross-linking reaction does not substantially proceed after lamination. In other words, the non-curable pressure-sensitive adhesive can be a so-called ordinary pressure-sensitive adhesive. The non-curable adhesive is excellent in productivity because it does not require light irradiation (photo-curing), and it can prevent the generation of dents, the adhesive squeezing out from the end of the punched product, and poor handling. can.

The storage elastic modulus at 60 ° C. before curing of the photocurable pressure-sensitive adhesive can substantially correspond to the storage elastic modulus at the time of laminating. The storage elastic modulus before curing is 1.0 × 10 ⁵ Pa or less, preferably 1.0 × 10 ³ Pa to 1.0 × 10 ⁵ Pa, as described above. The storage elastic modulus of the photocurable pressure-sensitive adhesive at 60 ° C. after curing is preferably 5.0 × 10 ³ Pa to 5.0 × 10 ⁵ Pa. The gel fraction of the photocurable pressure-sensitive adhesive before curing is 0% to 60%, and the gel fraction after curing is 50% to 95%. When the second pressure-sensitive adhesive layer is composed of a photocurable pressure-sensitive adhesive, the thickness of the second pressure-sensitive adhesive layer is preferably 50 μm to 500 μm, more preferably 75 μm to 475 μm, and further preferably 100 μm to 100 μm. It is 450 μm.

The storage elastic modulus at 60 ° C. when the non-curable pressure-sensitive adhesive is laminated is preferably 1.0 × 10 ³ Pa to 8.0 × 10 ⁴ Pa, and more preferably 5.0 × 10 ³ Pa to 6. It is 0 × 10 ⁴ Pa. When the second pressure-sensitive adhesive layer is composed of a non-curable pressure-sensitive adhesive, the thickness of the second pressure-sensitive adhesive layer is preferably 50 μm to 1000 μm, more preferably 75 μm to 900 μm, and further preferably 100 μm to 100 μm. It is 800 μm μm.

Hereinafter, the characteristics of the second pressure-sensitive adhesive layer and the photocurable pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer will be described, and then the non-curable pressure-sensitive adhesive will be briefly described.

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, still 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. When the glass transition temperature is in such a range, a second pressure-sensitive adhesive layer having excellent impact resistance can be realized.

The peak top value of the loss tangent tan δ of the second pressure-sensitive adhesive layer (that is, tan δ at the glass transition temperature) is preferably 1.5 or more, more preferably 1.6 or more, and further preferably 1.7. The above is particularly preferable, and it is 1.75 or more. On the other hand, the upper limit of the peak top value of tan δ is preferably 3.0 or less, more preferably 2.5 or less, and further preferably 2.3 or less. When the peak top value of tan δ is in such a range, the second pressure-sensitive adhesive layer exhibits appropriate deformation behavior (viscoelastic behavior), so that gaps are less likely to be formed in the deformed portion and delay bubbles are suppressed. obtain.

The total light transmittance of the second pressure-sensitive adhesive layer is preferably 85% or more, more preferably 90% or more. The haze value of the second pressure-sensitive adhesive layer is preferably 1.5% or less, more preferably 1.0% or less.

E-2. Photocurable adhesive E-2-1. Characteristics of Photocurable Adhesive The storage elastic modulus of the photocurable adhesive at 60 ° C. before curing is 1.0 × 10 ⁵ Pa or less, preferably 1.0 × 10 ³ Pa to 1. It is 0 × 10 ⁵ Pa, more preferably 5.0 × 10 ³ Pa to 8.0 × 10 ⁴ Pa, and even more preferably 7.5 × 10 ³ Pa to 6.0 × 10 ⁴ Pa. If the storage elastic modulus of the photocurable pressure-sensitive adhesive before curing is within such a range, the photo-curable pressure-sensitive adhesive exhibits appropriate deformation behavior (viscoelastic behavior) and flows well into every corner of the deformed portion. obtain. As a result, gaps are less likely to be formed in the deformed portion, and delay bubbles can be suppressed. The storage elastic modulus of the photocurable pressure-sensitive adhesive at 60 ° C. after curing is preferably 5.0 × 10 ³ Pa to 5.0 × 10 ⁵ Pa, and more preferably 7.5 × 10 ³ Pa to 4. It is 0 × 10 ⁵ Pa, more preferably 8.0 × 10 ³ Pa to 3.0 × 10 ⁵ Pa. If the storage elastic modulus of the photocurable pressure-sensitive adhesive after curing is within such a range, the gel elasticity of the second pressure-sensitive adhesive becomes low and the residual stress becomes small. As a result, the delay bubble can be suppressed.

The gel fraction of the photocurable pressure-sensitive adhesive before curing is preferably 0% to 60%, more preferably 0% to 55%, and even more preferably 0% to 50%. When the gel fraction of the photocurable pressure-sensitive adhesive before curing is within such a range, it is easy to realize the desired storage elastic modulus. Therefore, the photocurable pressure-sensitive adhesive exhibits appropriate deformation behavior (viscoelastic behavior) and can flow into every corner of the deformed portion satisfactorily. As a result, gaps are less likely to be formed in the deformed portion, and delay bubbles can be suppressed. The gel fraction after curing of the photocurable pressure-sensitive adhesive is preferably 50% to 95%, more preferably 55% to 93%, and further preferably 60% to 90%. When the gel fraction after curing of the photocurable pressure-sensitive adhesive is within such a range, the cover glass, the first polarizing plate, and the image display cell can be firmly fixed. As a result, the delay bubble can be suppressed. The gel fraction can be determined as an insoluble fraction in a solvent such as ethyl acetate. Specifically, the gel fraction is the weight fraction (unit: weight%) of the insoluble component after immersing the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in ethyl acetate at 23 ° C. for 7 days with respect to the sample before immersion. Is required as. The gel fraction can be adjusted by appropriately setting the type, combination and blending amount of the monomer components constituting the base polymer of the pressure-sensitive adhesive, and the type and blending amount of the cross-linking agent.

E-2-2. Constituent Material of Photocurable Adhesive As the photocurable adhesive, any suitable photocurable adhesive (in this section, it may be simply referred to as a pressure-sensitive adhesive composition) as long as it has the above-mentioned characteristics. There is) can be used. Examples of the base polymer of the pressure-sensitive adhesive composition include (meth) acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, and fluoropolymers. Examples thereof include rubber-based polymers such as natural rubber and synthetic rubber. A (meth) acrylic pressure-sensitive adhesive composition containing a (meth) acrylic polymer as a base polymer is preferable. This is because it is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness and adhesiveness, and is also excellent in weather resistance and heat resistance. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacrylic.

The (meth) acrylic base polymer (hereinafter, may be simply referred to as a base polymer) preferably has a crosslinked structure.

E-2-2-1. (Meta) Acrylic Base Polymer The (meth) acrylic base polymer contains an alkyl (meth) acrylate as a main monomer component. As the alkyl (meth) acrylate, an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms is preferably used. The alkyl (meth) acrylate may have a branched alkyl group or a cyclic alkyl group. The amount of the alkyl (meth) acrylate with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 40% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more. be. From the viewpoint of setting the glass transition temperature (Tg) of the polymer chain in an appropriate range, the alkyl (meth) acrylate having a chain alkyl group having 4 to 10 carbon atoms with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer. The amount is preferably 30% by weight or more, more preferably 40% by weight or more, and further preferably 45% by weight or more.

The (meth) acrylic-based base polymer preferably contains a monomer component having a crosslinkable functional group. With such a configuration, the gel fraction of the pressure-sensitive adhesive can be adjusted to a desired range. Examples of the monomer component having a crosslinkable functional group include a hydroxyl group-containing monomer and a carboxy group-containing monomer. When the crosslinked structure is introduced by the isocyanate cross-linking agent, the hydroxyl group becomes the reaction point with the isocyanate group, and when the crosslinked structure is introduced by the epoxy-based cross-linking agent, the carboxy group becomes the reaction point with the epoxy group. Preferably, a hydroxyl group-containing monomer is used as a monomer component having a crosslinkable functional group, and a crosslinked structure can be introduced by an isocyanate-based crosslinking agent. With such a configuration, the crosslinkability of the base polymer is enhanced, and a highly transparent second pressure-sensitive adhesive layer can be obtained. Further, with such a configuration, a so-called acid-free pressure-sensitive adhesive can be realized.

The amount of the hydroxyl group-containing monomer with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 5% by weight to 30% by weight, more preferably 8% by weight to 25% by weight, still more preferably 10. It is from% by weight to 20% by weight. When the amount of the hydroxyl group-containing monomer is in such a range, the degree of cross-linking (gel fraction) can be increased with a small amount of the cross-linking agent, and as a result, the filling property of the photocurable pressure-sensitive adhesive before curing and the filling property of the deformed portion Operability can be improved. Furthermore, since unreacted hydroxyl groups can form intermolecular hydrogen bonds after cross-linking, a desired storage elastic modulus can be achieved even if the gel fraction is small.

When the second pressure-sensitive adhesive layer can come into contact with the touch panel sensor, for example, the second pressure-sensitive adhesive layer preferably has a small acid content in order to prevent corrosion of the electrode by the acid component. In this case, the amount of the carboxy group-containing monomer with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 0.5% by weight or less, more preferably 0.1% by weight or less, still more preferable. Is 0.05% by weight or less, ideally 0 (zero). With such a configuration, the acid content in the photocurable pressure-sensitive adhesive can be preferably 100 ppm or less, more preferably 70 ppm or less, still more preferably 50 ppm or less.

The (meth) acrylic base polymer may contain a nitrogen-containing monomer as a monomer component. The (meth) acrylic-based base polymer appropriately contains a highly polar monomer such as a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a nitrogen-containing monomer as a monomer component, thereby achieving storage elasticity, adhesive retention, and impact resistance. A well-balanced second pressure-sensitive adhesive layer can be formed. The amount of highly polar monomer (total of hydroxyl group-containing monomer, carboxy group-containing monomer and nitrogen-containing monomer) with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 10% by weight to 45% by weight, more preferably. Is 15% by weight to 40% by weight, more preferably 18% by weight to 35% by weight. In particular, it is preferable that the total of the hydroxyl group-containing monomer and the nitrogen-containing monomer is within the above range. The amount of the nitrogen-containing monomer with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 3% by weight to 25% by weight, more preferably 5% by weight to 20% by weight, still more preferably 7. It is from% by weight to 15% by weight.

The (meth) acrylic polymer may further contain any suitable monomer component depending on the purpose. Specific examples of such a monomer component include an acid anhydride group-containing monomer, a caprolactone additive of (meth) acrylic acid, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, vinyl acetate, vinyl propionate, styrene, and α-. Vinyl-based monomers such as methylstyrene; cyano group-containing acrylic monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing monomers such as glycidyl (meth) acrylate; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate. , (Meta) methoxyethylene glycol acrylate, (meth) methoxypolypropylene glycol, and other glycol-based acrylic ester monomers; (meth) tetrahydrofurfuryl acrylate, fluorine (meth) acrylate, silicone (meth) acrylate, (meth) Examples thereof include acrylic acid ester-based monomers such as 2-methoxyethyl acrylate.

The (meth) acrylic base polymer preferably contains the most alkyl (meth) acrylate as a monomer component, and more preferably contains the most alkyl (meth) acrylate having a chain alkyl group having 6 or less carbon atoms. With such a configuration, the peak top value of tan δ becomes large, and the impact resistance can be improved. The amount of the alkyl (meth) acrylate having a chain alkyl group having 6 or less carbon atoms with respect to the total amount of the monomer components constituting the (meth) acrylic base polymer is preferably 30% by weight to 80% by weight, more preferably 35. It is from% by weight to 75% by weight, more preferably 40% by weight to 70% by weight. In particular, the content of butyl acrylate as a monomer component is preferably in the above range.

The glass transition temperature (Tg) of the (meth) acrylic base polymer is preferably −50 ° C. or higher. On the other hand, the Tg of the (meth) acrylic base polymer is preferably −5 ° C. or lower, more preferably −10 ° C. or lower, and further preferably −15 ° C. or lower.

E-2-2-2. Cross-linked structure For a polymer in which a cross-linked structure is introduced into a (meth) acrylic base polymer, for example, (1) a (meth) acrylic polymer having a functional group capable of reacting with a cross-linking agent is polymerized, and then a cross-linking agent is added. , (Meta) A method of reacting an acrylic polymer with a cross-linking agent; and (2) A method of introducing a branched structure (cross-linked structure) into a polymer chain by including a polyfunctional compound in the polymer component of the polymer, etc. Obtained by These may be used together.

Specific examples of the cross-linking agent in the method of reacting the base polymer of the above (1) with the cross-linking agent include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a carbodiimide-based cross-linking agent, and a metal. Examples thereof include a chelate-based cross-linking agent. Of these, isocyanate-based cross-linking agents and epoxy-based cross-linking agents are preferable because they have high reactivity with the hydroxyl groups and carboxy groups of the base polymer and the cross-linking structure can be easily introduced. These cross-linking agents react with functional groups such as hydroxyl groups and carboxy groups introduced into the base polymer to form a cross-linked structure. As described above, when an acid-free pressure-sensitive adhesive containing no carboxy group is used as the base polymer, it is preferable to introduce a cross-linked structure by using a hydroxyl group in the base polymer and an isocyanate-based cross-linking agent.

The cross-linking agent is preferably 0.03 parts by weight to 0.5 parts by weight, more preferably 0.05 parts by weight to 0.3 parts by weight, and further preferably 0.06 parts by weight with respect to 100 parts by weight of the base polymer. It can be used in a proportion of up to 0.25 parts by weight, particularly preferably 0.07 parts by weight to 0.2 parts by weight. By setting the amount of the cross-linking agent used in such a range, the gel fraction can be set in the above-mentioned desired range.

E-2-2-3. Polyfunctional compound In the method of including the polyfunctional compound in the polymerization component of the base polymer of the above (2), the total amount of the monomer component constituting the (meth) acrylic base polymer and the polyfunctional compound for introducing the crosslinked structure is simultaneously. The reaction may be carried out, or the polymerization may be carried out in multiple steps. As a method of performing polymerization in multiple steps, a partial polymer (prepolymer composition) is prepared by polymerizing (prepolymerizing) a monofunctional monomer constituting a (meth) acrylic base polymer, and the prepolymer composition is obtained. A method of polymerizing (mainly polymerizing) the prepolymer composition and the polyfunctional monomer by adding a polyfunctional compound such as a polyfunctional (meth) acrylate is preferable. The prepolymer composition is a partial polymer containing a polymer having a low degree of polymerization and an unreacted monomer.

By prepolymerizing the constituents of the (meth) acrylic base polymer, branch points (crosslinking points) due to the polyfunctional compound can be uniformly introduced into the (meth) acrylic base polymer. Further, after applying a low molecular weight polymer or a mixture of a partial polymer and an unpolymerized monomer component (adhesive composition) on a substrate, the main polymerization is performed on the substrate to form an adhesive layer. You can also do it. Since low-polymerization compositions such as prepolymer compositions have low viscosity and excellent coatability, it is a method of performing main polymerization on a substrate after applying a pressure-sensitive adhesive composition which is a mixture of a prepolymer composition and a polyfunctional compound. Therefore, the productivity of the pressure-sensitive adhesive layer can be improved, and the thickness of the pressure-sensitive adhesive layer can be made uniform.

Examples of the polyfunctional compound used for introducing the crosslinked structure include compounds containing two or more polymerizable functional groups (ethylenically unsaturated groups) having an unsaturated double bond in one molecule. The polyfunctional compound is typically a photopolymerizable polyfunctional compound. As the polyfunctional compound, a polyfunctional (meth) acrylate is preferable because it can be easily copolymerized with the monomer component of the (meth) acrylic polymer. When a branched (crosslinked) structure is introduced by active energy ray polymerization (photopolymerization), polyfunctional (meth) acrylate is preferable.

The molecular weight of the polyfunctional compound is preferably 1500 or less, more preferably 1000 or less. The lower limit of the molecular weight can 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 pressure-sensitive adhesive can be appropriately adjusted.

The polyfunctional compound is preferably in an amount of 1 part by weight to 6 parts by weight, more preferably 2 parts by weight to 5 parts by weight, and further preferably 2.5 parts by weight to 4 parts by weight with respect to 100 parts by weight of the base polymer. Can be used. If the amount used is too small, the adhesive retention of the photocurable pressure-sensitive adhesive (as a result, the second pressure-sensitive adhesive layer) may be insufficient. If the amount used is too large, the formed second pressure-sensitive adhesive layer may become excessively hard, resulting in insufficient impact resistance. Further, the processability and / or the processed dimensional stability of the photocurable pressure-sensitive adhesive may be insufficient.

In one embodiment, the polyfunctional compound may preferably be a compound containing three or more photopolymerizable functional groups in one molecule, more preferably three photopolymerizable functional groups in one molecule. It may be a (meth) acrylate containing the above. By using a trifunctional or higher functional photopolymerizable compound, the adhesive retention of the photocurable pressure-sensitive adhesive (as a result, the second pressure-sensitive adhesive layer) can be further enhanced. A bifunctional photopolymerizable compound and a trifunctional or higher functional photopolymerizable compound may be used in combination. The trifunctional or higher photopolymerizable compound is preferably 0.5 parts by weight to 5 parts by weight, more preferably 1 part by weight to 4.5 parts by weight, still more preferably 2 parts by weight, based on 100 parts by weight of the base polymer. It can be used in a proportion of up to 4 parts by weight.

E-2-2-4. Adhesive Composition The adhesive composition (photocurable adhesive) is, in addition to the above-mentioned base polymer, cross-linking agent and polyfunctional compound, a photopolymerization initiator, an oligomer, a silane coupling agent, and an arbitrary depending on the purpose. May contain suitable additives.

Examples of the photopolymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, and a photoactive oxime-based photopolymerization initiator. Examples thereof include 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. The photopolymerization initiator may be used alone or in combination of two or more. The content of the photopolymerization initiator in the pressure-sensitive adhesive composition is preferably 0.01 parts by weight to 5 parts by weight, more preferably 0.05 parts by weight to 3 parts by weight with respect to 100 parts by weight of the base polymer. be.

As the oligomer, any suitable oligomer can be used. By using the oligomer, the viscoelasticity (and therefore, the filling property of the deformed processed portion and the workability) and the adhesive force of the photocurable pressure-sensitive adhesive can be adjusted. The oligomer is preferably a (meth) acrylic oligomer. The (meth) acrylic oligomer can be excellent in compatibility with the base polymer.

The weight average molecular weight of the oligomer is preferably about 1000 to 30,000, more preferably 1500 to 10000, and even more preferably 2000 to 8000. When the weight average molecular weight of the oligomer is in such a range, excellent adhesive strength and adhesive retention can be realized.

The Tg of the oligomer is preferably 20 ° C. or higher, more preferably 50 ° C. or higher, still 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 further preferably 160 ° C. or lower. When the Tg of the oligomer is in such a range, a second pressure-sensitive adhesive layer having excellent adhesive strength can be formed.

The content of the oligomer in the pressure-sensitive adhesive composition is preferably 0.1 part by weight to 10 parts by weight, and more preferably 0.2 parts by weight to 5 parts by weight with respect to 100 parts by weight of the base polymer. When the content of the oligomer is in such a range, it is possible to form a second pressure-sensitive adhesive layer having excellent adhesive strength while maintaining good processability and processing dimensional stability of the photocurable pressure-sensitive adhesive. can.

As the silane coupling agent, any suitable silane coupling agent can be used. By using a silane coupling agent, the adhesive strength of the photocurable pressure-sensitive adhesive can be adjusted. The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.01 parts by weight to 5 parts by weight, more preferably 0.03 parts by weight to 2 parts by weight, based on 100 parts by weight of the base polymer. be.

As for the additive, any suitable additive according to the purpose can be used.

In one embodiment, the pressure-sensitive adhesive composition (photocurable pressure-sensitive adhesive) has a thickness corresponding to the thickness of the second pressure-sensitive adhesive layer, and is used as a pressure-sensitive adhesive sheet with a release film temporarily attached to both sides. Can be provided.

Further details of the pressure-sensitive adhesive composition (photocurable pressure-sensitive adhesive) are described in Japanese Patent Application No. 2018-218422 by the present applicant. The description of this application is incorporated herein by reference.

E-3. Non-curable pressure-sensitive adhesive As the non-curable pressure-sensitive adhesive, any suitable non-curable pressure-sensitive adhesive can be used as long as it has the above-mentioned characteristics. By appropriately adjusting the types, combinations, blending amounts, etc. of the monomer components, and the types, numbers, combinations, blending amounts, etc. of the cross-linking agents, silane coupling agents, and additives, the above-mentioned desired storage elastic modulus can be obtained. A curable pressure-sensitive adhesive (as a result, a second pressure-sensitive adhesive layer) can be obtained. Examples of the non-curable pressure-sensitive adhesive include the pressure-sensitive adhesive described in Section C above with respect to the first and second pressure-sensitive adhesive layers, the pressure-sensitive adhesive described in Japanese Patent Application No. 2019-196942 by the present applicant, and JP-A-2016-94569. Examples thereof include the pressure-sensitive adhesive described in the publication. The description of the application and the gazette are incorporated herein by reference.

E-4. Set of Optical Members As described above, the pressure-sensitive adhesive (adhesive composition) constituting the second pressure-sensitive adhesive layer can be provided as a pressure-sensitive adhesive sheet. In the manufacture of an image display device, the pressure-sensitive adhesive sheet may be provided as a set of optical members together with a polarizing plate according to an embodiment of the present invention. Therefore, such a set of optical members is also included in the embodiments of the present invention. In one embodiment, the set of optics may further include another polarizing plate (backside polarizing plate). That is, in the production of the image display device, the pressure-sensitive adhesive sheet, the polarizing plate (visualizing side polarizing plate) and the second polarizing plate (back surface side polarizing plate) according to the embodiment of the present invention can be provided as a set of optical members.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluation items in the examples are as follows. Further, unless otherwise specified, "parts" and "%" in the examples are based on weight.

(1) Size of Adhesive Voids Observe the state of the cross section of the adhesive layer in the through holes of the polarizing plates used in Examples and Comparative Examples with an optical microscope, and observe the state of the adhesive layer from the outer edge to the inward in the plane direction. The length of the portion where the chipping was maximum was measured, and the size of the adhesive void portion was L (μm).
(2) Amount of glue misalignment The polarizing plates used in Examples and Comparative Examples were bonded to glass, autoclaved (50 ° C / 0.5 MPa / 15 min), and then subjected to a heating test (85 ° C, 120 h). .. The through hole of the sample after the test was observed with an optical microscope, and the deformed portion of the adhesive at the end of the polarizing plate of the through hole was measured and used as the displacement amount of the through hole. The deformed portion was measured with an optical microscope (MX61L) manufactured by OLYMPUS. The measurement was performed on three test samples, and the maximum value among the three measured values was taken as the deviation amount.
(3) Bubble evaluation The image display device compatible products obtained in Examples and Comparative Examples were subjected to autoclave treatment (50 ° C / 0.5 MPa / 15 min) after vacuum laminating and UV cured (illuminance 150 mW / cm ² at 3000 mJ. Irradiation amount) was performed. Then, the sample was put into a heating test (85 ° C., 24 hours), and when it was taken out, the state of bubbles was observed visually or by an optical microscope. The measurement was carried out at n = 6 and evaluated according to the following criteria.
4: No bubbles are seen in all samples
3: There are slight bubbles in less than half of the samples, but there is no problem in use.
2: Slight bubbles are seen in more than half of the samples, but there is no problem in use.
1: All samples have bubbles

<Manufacturing Example 1: Preparation of Adhesive Layer (1)>
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler was charged with a monomer mixture containing 99 parts of butyl acrylate (BA) and 1 part of 4-hydroxybutyl acrylate. Further, with respect to 100 parts of the monomer mixture (solid content), 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator is charged together with 100 parts by weight of ethyl acetate, and nitrogen gas is added while gently stirring. After the introduction and substitution with nitrogen, the liquid temperature in the flask was maintained at around 55 ° C. and the polymerization reaction was carried out for 8 hours to prepare a solution of the acrylic polymer. For 100 parts of the solid content of the obtained acrylic polymer solution, 0.3 part of benzoyl peroxide (trade name: Niper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.) as a cross-linking agent, and an isocyanate-based cross-linking agent (commodity). Name: Takenate D110N, 0.1 part of Mitsui Chemicals Co., Ltd., and 0.2 parts of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) are blended to form a pressure-sensitive adhesive. I got something.
Next, the solution of the acrylic pressure-sensitive 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, and the pressure-sensitive adhesive layer after drying was applied. The film was applied to a thickness of 20 μm and 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 pressure-sensitive adhesive layer (1) was 120 μm / hr.

<Manufacturing Example 2: Preparation of Adhesive Layer (2)>
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler contains 94.9 parts of butyl acrylate (BA), 5 parts of acrylic acid, and 0.1 part of 4-hydroxybutyl acrylate. A mixture of monomers was charged. Further, with respect to 100 parts of the monomer mixture (solid content), 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator is charged together with 100 parts by weight of ethyl acetate, and nitrogen gas is added while gently stirring. After the introduction and substitution with nitrogen, the liquid temperature in the flask was maintained at around 55 ° C. and the polymerization reaction was carried out for 8 hours to prepare a solution of the acrylic polymer. Benzoyl peroxide as a cross-linking agent (trade name: Niper BMT 40SV, manufactured by Nippon Oil & Fats Co., Ltd.) 0.1 part, isocyanate-based cross-linking agent (commodity) with respect to 100 parts of the solid content of the obtained acrylic polymer solution. Name: Coronate L, 8 parts manufactured by Toso Co., Ltd., and 0.2 part of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) are blended to obtain a pressure-sensitive adhesive composition. rice field.
Next, the solution of the acrylic pressure-sensitive 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, and the pressure-sensitive adhesive layer after drying was applied. The film was applied to a thickness of 20 μm and 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 pressure-sensitive adhesive layer (2) was 35 μm / hr.

<Production Example 3: Preparation of a photocurable pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer>
Contains 65 parts of butyl acrylate (BA), 5 parts of cyclohexyl acrylate (CHA), 10 parts of N-vinyl-2-pyrrolidone (NVP), 15 parts of 4-hydroxybutyl acrylate (4HBA) and 5 parts of isostearyl acrylate (ISTA). A mixture of monomers was charged. Further, with respect to 100 parts of the monomer mixture (solid content), 0.2 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 0.065 parts of α-thioglycerol (TGR) as a chain transfer agent were added. The mixture was charged with 233 parts by weight of ethyl acetate, stirred for 1 hour in a nitrogen atmosphere at 23 ° C., and subjected to nitrogen substitution. 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 the acrylic base polymer. The following post-additional components were added to 100 parts of the base polymer to the solution of the acrylic base polymer obtained above and uniformly mixed to prepare a photocurable pressure-sensitive adhesive b. The storage elastic modulus of the photocurable pressure-sensitive adhesive b at 60 ° C. before curing was 4.7 × 10 ⁴ Pa, and the storage elastic modulus at 60 ° C. after curing was 1.0 × 10 ⁵ Pa. The gel fraction before curing was 40%, and the gel fraction after curing was 80%.
(Post-added ingredient)
Dipentaerythritol hexaacrylate as a polyfunctional compound (photocuring agent): Part 2 Polypropylene glycol diacrylate as a polyfunctional compound (photocuring agent) (trade name: APG400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., polypropylene glycol # 400 ( n = 7) Diacrylate, functional group equivalent 268 g / eq): 3 parts Photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF): 0.2 parts (preparation of adhesive sheet)
A photocurable adhesive b is applied to a 75 μm-thick polyethylene terephthalate (PET) film (“Diafoil MRF75” manufactured by Mitsubishi Chemical Corporation) provided with a silicone-based release layer on the surface, and heated at 100 ° C. for 3 minutes. After removing the solvent, the same release PET film as above was attached to the surface. The laminate thus obtained was aged at 25 ° C. for 3 days to obtain a pressure-sensitive adhesive sheet I on which a release film was temporarily attached to both sides.

<Manufacturing Example 4: Fabrication of Polarizing Plate>
A 30 μm-thick polyvinyl alcohol film was stretched up to 3 times while being dyed in an iodine solution at 30 ° C. and a 0.3% concentration for 1 minute between rolls having different speed ratios. Then, the total stretch ratio was stretched to 6 times while being immersed in an aqueous solution containing boric acid at 60 ° C. and a concentration of 4% and potassium iodide at a concentration of 10% for 0.5 minutes. Then, it was washed by immersing it in an aqueous solution containing potassium iodide having a concentration of 1.5% at 30 ° C. for 10 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarizing element having a thickness of 12 μm. A triacetyl cellulose (TAC) film with a hard coat (hard coat thickness 2 μm, TAC thickness 25 μm) serving as an outer protective layer and a TAC film (thickness 25 μm) serving as an inner protective layer were bonded to both sides of the polarizing element. The liquid crystal oriented solidified layer H and the liquid crystal oriented solidified layer Q were sequentially transferred to the inner protective layer side of this polarizing plate. In this way, the polarizing plate (1) was produced. The liquid crystal oriented solidified layer H and the liquid crystal oriented solidified layer Q were produced as follows.

ポリエチレンテレフタレート（ＰＥＴ）フィルム（厚み３８μｍ）表面を、ラビング布を用いてラビングし、配向処理を施した。配向処理の方向は、偏光板に貼り合わせる際に偏光子の吸収軸の方向に対して視認側から見て１５°方向となるようにした。この配向処理表面に、上記液晶塗工液をバーコーターにより塗工し、９０℃で２分間加熱乾燥することによって液晶化合物を配向させた。このようにして形成された液晶層に、メタルハライドランプを用いて１ｍＪ/ｃｍ^２の光を照射し、当該液晶層を硬化させることによって、ＰＥＴフィルム上に液晶配向固化層Ｈを形成した。液晶配向固化層Ｈの厚みは２．５μｍ、面内位相差Ｒｅ（５５０）は２７０ｎｍであった。さらに、液晶配向固化層Ｈは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。塗工厚みを変更したこと、および、配向処理方向を偏光子の吸収軸の方向に対して視認側から見て７５°方向となるようにしたこと以外は上記と同様にして、ＰＥＴフィルム上に液晶配向固化層Ｑを形成した。液晶配向固化層Ｑの厚みは１．５μｍ、面内位相差Ｒｅ（５５０）は１４０ｎｍであった。さらに、液晶配向固化層Ｑは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name "Pariocolor LC242", represented by the following formula) and a photopolymerization initiator (manufactured by BASF: trade name "Irgacure 907") for the polymerizable liquid crystal compound. ) 3g was dissolved in 40g of toluene to prepare a liquid crystal composition (coating liquid).

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth and subjected to an orientation treatment. The direction of the alignment treatment was set to be 15 ° when viewed from the visual recognition side with respect to the direction of the absorption axis of the polarizing element when the polarizing plate was attached. The liquid crystal coating liquid was applied to the alignment-treated surface with a bar coater, and the liquid crystal compound was oriented by heating and drying at 90 ° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with light of 1 mJ / cm ² using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal oriented solidified layer H on the PET film. The thickness of the liquid crystal oriented solidified layer H was 2.5 μm, and the in-plane retardation Re (550) was 270 nm. Further, the liquid crystal oriented solidified layer H had a refractive index distribution of nx> ny = nz. On the PET film in the same manner as above, except that the coating thickness was changed and the orientation processing direction was set to be 75 ° when viewed from the visual side with respect to the direction of the absorber's absorption axis. A liquid crystal oriented solidified layer Q was formed. The thickness of the liquid crystal oriented solidified layer Q was 1.5 μm, and the in-plane retardation Re (550) was 140 nm. Further, the liquid crystal oriented solidified layer Q had a refractive index distribution of nx> ny = nz.

<Manufacturing Example 5: Fabrication of Polarizing Plate>
A 30 μm-thick polyvinyl alcohol film was stretched up to 3 times while being dyed in an iodine solution at 30 ° C. and a 0.3% concentration for 1 minute between rolls having different speed ratios. Then, the total stretch ratio was stretched to 6 times while being immersed in an aqueous solution containing boric acid at 60 ° C. and a concentration of 4% and potassium iodide at a concentration of 10% for 0.5 minutes. Then, it was washed by immersing it in an aqueous solution containing potassium iodide having a concentration of 1.5% at 30 ° C. for 10 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarizing element having a thickness of 12 μm. A triacetyl cellulose (TAC) film with a hard coat (hard coat thickness 2 μm, TAC thickness 25 μm) serving as an outer protective layer and an acrylic resin film (thickness 20 μm) serving as an inner protective layer are laminated on both sides of the polarizing element to obtain polarization. A plate (2) was produced.

<Manufacturing Example 6: Fabrication of Polarizing Plate>
1. 1. Preparation of Polarizer As the thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape, a water absorption of 0.75%, and a Tg of about 75 ° C. was used. One side of the resin substrate was corona-treated.
100 weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") are mixed at a ratio of 9: 1. A PVA aqueous solution (coating solution) was prepared by dissolving 13 parts by weight of potassium iodide in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm, and a laminate was prepared.
The obtained laminate was stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water), the polarizing film finally obtained is charged. It was immersed for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) became a predetermined value (staining treatment).
Then, it was immersed in a cross-linked bath having a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight) having a liquid temperature of 70 ° C., the rolls having different peripheral speeds are subjected to the longitudinal direction (longitudinal direction). ) Was uniaxially stretched so that the total stretch ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75 ° C. for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment was 5.2%.
In this way, a polarizing element having a thickness of 5 μm was formed on the resin substrate.

2. 2. Preparation of Polarizing Plate An HC-TAC film was attached to the surface of the polarizing element of the resin substrate / polarizing element laminate obtained above via an ultraviolet curable adhesive. Specifically, the curable adhesive was coated so as to have 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 (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film is attached so as to be on the splitter side. I matched it. Next, the resin base material was peeled off, and a TAC film (thickness 20 μm) was attached to the peeled surface in the same manner as described above. In this way, the polarizing plate (3) was produced.

<Example 1>
1. 1. Formation of Through Holes The pressure-sensitive adhesive layer (1) obtained in Production Example 1 was formed on the surface of the liquid crystal oriented solidified layer Q of the polarizing plate (1) obtained in Production Example 4, and the polarizing plate with the pressure-sensitive adhesive layer was formed. bottom. The polarizing plate with the pressure-sensitive adhesive layer was punched out to a size of 145 mm in length and 68 mm in width. At this time, the polarizing element was punched so that the absorption axis direction was 135 ° clockwise with respect to the long side direction. Further, a through hole having 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 FIG. 1A was produced. _The | b1 _- b2 | in the obtained polarizing plate was 0 mm. Further, the size L of the pressure-sensitive adhesive gap was 90 μm. This polarizing plate was used for the evaluation of (2) above. The results are shown in Table 1.

2. 2. Manufacture of products compatible with image display devices On one side of a glass plate (corresponding to an image display cell), the above 1. The polarizing plate with the pressure-sensitive adhesive layer obtained in 1 above was bonded via the pressure-sensitive adhesive layer. Next, one of the release films of the pressure-sensitive adhesive sheet I obtained in Production Example 3 was peeled off and bonded to a cover glass (manufactured by Matsunami Glass Co., Ltd., thickness 0.8 mm) with a roll laminator. Next, the other release film of the pressure-sensitive adhesive sheet I was peeled off, and the surface of the polarizing plate with the pressure-sensitive adhesive layer was brought into close contact with the surface using a vacuum laminator, and the through holes were filled with the pressure-sensitive adhesive sheet. The conditions for vacuum laminating were as follows: heating and crimping at 0.2 MPa, 60 ° C. (standby time 90 seconds), and then vacuum laminating at 100 Pa for 10 seconds. Further, the photocurable pressure-sensitive adhesive was cured by irradiating ultraviolet rays with an integrated light amount of 3000 mJ / cm ² from the cover glass side with a metal halide lamp (300 mW / cm ² ). After that, an autoclave treatment (50 ° C./0.5 MPa/15 min) was performed. In this way, a product compatible with the image display device was manufactured. The obtained image display device compatible product was subjected to the bubble evaluation in (3) above. The results are shown in Table 1.

<Example 2>
A polarizing plate (polarizing plate with an adhesive layer) and a product compatible with an image display device were produced in the same manner as in Example 1 except that the through hole was formed at the end in the long side direction and the central portion in the short side direction. _The | b1 _- b2 | in the obtained polarizing plate was 41 mm. Further, the size L of the pressure-sensitive adhesive gap was 90 μm. The obtained polarizing plate and the product corresponding to the image display device were subjected to the same evaluation as in Example 1, respectively. The results are shown in Table 1. In Table 1, the end portion in the long side direction and the central portion in the short side direction are simply referred to as "center".

<Examples 3 to 7 and Comparative Examples 1 to 4>
The polarizing plate (polarizing plate with adhesive layer) and the image are the same as in Example 1 except that the type and size of the polarizing plate, the type of the pressure-sensitive adhesive layer, and the formation position of the through hole are shown in Table 1. A product compatible with the display device was manufactured. The size L of the pressure-sensitive adhesive gap was adjusted by changing the feed rate, rotation speed, and cutting amount of the drill during the end milling process for forming the through hole. Here, Examples 4 and 6 correspond to the form shown in FIG. 1A, Example 7 corresponds to the form shown in FIG. 1B, and Examples 3 and 5 correspond to the form shown in FIG. 1C. The obtained polarizing plate and the product corresponding to the image display device were subjected to the same evaluation as in Example 1, respectively. The results are shown in Table 1.

As is clear from Table 1, in the polarizing plate of the embodiment of the present invention, the amount of glue misalignment in the through-hole portion after the heating test is remarkably smaller than that of the comparative example, and the delay bubble is suppressed. Understand.

The polarizing plate of the present invention is suitably used for an image display device, and can be particularly preferably used for an image display device having a camera unit represented by a smartphone, a tablet PC or a smart watch.

11 Polarizer 12 Outer protective layer 13 Inner protective layer 20 Adhesive layer 30 Through hole 100 Polarizing plate

Claims (7)

It has a polarizing element, a protective layer arranged on at least one side of the polarizing element, and an adhesive layer.
Through holes are formed,
The thickness of the polarizing element is 15 μm or less, and the thickness is 15 μm or less.
| B ₁ -b ₂ | is 45 mm or less,
Polarizer:
Here, b ₁ is the distance from the center of the through hole to one end of the polarizing plate in the absorption axis direction of the substituent, and b ₂ 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 splitter. The distance to the edge. The first aspect of the present invention, wherein the polarizing element has a rectangular shape, the absorption axis direction of the polarizing element is 135 ° clockwise from the long side direction, and the through hole is formed in the right corner. Polarizing plate. The first aspect of the present invention, wherein the polarizing element has a rectangular shape, the absorption axis direction of the polarizing element is 45 ° clockwise from the long side direction, and the through hole is formed in the left corner. Polarizer. Claimed, which has a rectangular shape, the absorption axis direction of the polarizing element is the short side direction, and the through hole is formed at the end portion in the long side direction and the central portion in the short side direction when viewed in a plan view. The polarizing plate according to 1. The polarizing plate according to any one of claims 1 to 4, wherein the polarizing element has a thickness of 8 μm or less. The polarizing plate according to any one of claims 1 to 5, wherein the creep value of the pressure-sensitive adhesive layer is 140 μm / hr or less. The image display cell and the polarizing plate according to any one of claims 1 to 6 are included.
The polarizing plate is attached to the image display cell via the pressure-sensitive adhesive layer.
Image display device.

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