Polarizing plate and polarizing plate with phase difference layer, and method for manufacturing polarizing plate

Abstract

Provided are a polarizing plate and a polarizing plate with a retardation layer, both of which are excellent in adhesive layer peeling, handling, and quality uniformity, and a method for manufacturing such a polarizing plate. The polarizing plate of the present invention is a polarizing plate having a surface treatment layer, a polarizer, and an adhesive layer in this order, and formed with a through-hole, and in at least a part of an end portion of the adhesive layer in a plane direction of the polarizing plate, an end portion adhesive recess portion is formed, and a maximum length of the end portion adhesive recess portion in the plane direction of the polarizing plate is 50 μm or more.

Description

Technical Field

[0001] This invention relates to polarizers, polarizers with phase retardation layers, and methods for manufacturing polarizers. Background Technology

[0002] In recent years, image display devices, represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices), have become increasingly popular. Polarizing films are typically used in image display devices. In such polarizing films, an adhesive layer is used for bonding the polarizing film layers to each other or to other components (see Patent Document 1).

[0003] This issue arises during the handling and inspection of polarizers, where adhesive from the adhesive layer sometimes peels off. This can lead to uneven formation of adhesive peeling areas within the adhesive layer, causing problems with the operability and uniformity of the polarizer's quality.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2020-170152 Summary of the Invention

[0005] The problem that the invention aims to solve The present invention was made to solve the above-mentioned prior art problems, and its main objective is to provide a polarizer and a polarizer with a phase retardation layer that reduce the peeling of adhesive from the adhesive layer, have excellent operability and quality uniformity, and a method for manufacturing such a polarizer.

[0006] Methods for solving problems [1] The polarizer of the present invention is a polarizer having a surface treatment layer, a polarizer and an adhesive layer in sequence and having a through hole. In the surface direction of the polarizer, an end adhesive recess is formed in at least a portion of the end of the adhesive layer, and the maximum length of the end adhesive recess in the surface direction of the polarizer is 50 μm or more.

[0007] [2] In the polarizer described in [1] above, a through hole adhesive recess is formed in at least a portion of the outer periphery of the through hole in the adhesive layer, and the maximum length of the through hole adhesive recess in the surface direction of the polarizer is 20 μm or more.

[0008] [3] In the polarizer described in [1] or [2] above, the adhesive layer is configured as the outermost layer.

[0009] [4] In the polarizer described in [2] above, the length of the through hole adhesive recess in the surface direction of the polarizer is longer in the central region than that in the thickness direction of the adhesive layer compared with the layer interface.

[0010] [5] In any one of the polarizers described in [1] to [4] above, a protective layer is provided between the surface treatment layer and the polarizer.

[0011] [6] In any one of the polarizers described in [1] to [5] above, the storage elastic modulus G' of the adhesive layer at 25°C is 0.10 MPa or more.

[0012] [7] In any one of the polarizers described in [1] to [6] above, the thickness of the surface treatment layer is 1.0 μm or more.

[0013] [8] In any one of the polarizers described in [1] to [7] above, the thickness of the adhesive layer is 15 μm or more.

[0014] [9] In any one of the polarizers described in [1] to [8] above, the diameter of the through hole is 2 mm or more.

[0015]

[10] A polarizer with a phase difference layer, comprising any one of the polarizers described in [1] to [9] above, wherein the phase difference layer is present between the polarizer and the adhesive layer.

[0016]

[11] The method for manufacturing a polarizer according to any one of [1] to [9] above includes: a stacking step of sequentially stacking the surface treatment layer, the polarizer, and the adhesive layer to obtain a strip-shaped optical laminate; a punching step of punching the strip-shaped optical laminate into a rectangular shape using a first processing tool; an end processing step of cutting the end of the optical laminate using a second processing tool; and a through-hole forming step of forming the through-hole in the optical laminate using a third processing tool. In the end processing step, a clamping force of 1000 N or more is applied to the optical laminate along the thickness direction of the optical laminate, and the tool angle of the second processing tool is 25° or more.

[0017]

[12] In the method for manufacturing the polarizer described in

[11] above, in the end processing step, a clamping force of 2000 N or more is applied to the optical laminate along the thickness direction of the optical laminate.

[0018]

[13] In the method for manufacturing polarizer described in

[11] or

[12] above, in the through hole forming process, a clamping force of 1000 N or more is applied to the optical laminate along the thickness direction of the optical laminate, and the tool angle of the third processing tool is 25° or more; or, a clamping force of 2000 N or more is applied to the optical laminate along the thickness direction of the optical laminate, and the tool angle of the third processing tool is 15° or more.

[0019]

[14] In the method for manufacturing polarizer described in

[13] above, in the through hole forming process, a clamping force of 1000 N or more is applied to the optical laminate along the thickness direction of the optical laminate, and the tool angle of the third processing tool is 25° or more.

[0020]

[15] In the method for manufacturing the polarizer described in

[14] above, in the through hole forming process, a clamping force of 2000 N or more is applied to the optical laminate along the thickness direction of the optical laminate.

[0021] Invention Effects According to embodiments of the present invention, it is possible to provide polarizers with reduced adhesive detachment from the adhesive layer, excellent operability and uniformity, polarizers with phase retardation layers, and methods for manufacturing such polarizers. Attached Figure Description

[0022] Figure 1 This is a schematic cross-sectional view illustrating one embodiment of the polarizer of the present invention.

[0023] Figure 2 This is a schematic cross-sectional view illustrating another embodiment of the polarizer of the present invention.

[0024] Figure 3 This is a schematic cross-sectional view illustrating another embodiment of the polarizer of the present invention.

[0025] Figure 4 This is a partial enlarged rough cross-sectional view of the adhesive layer in a polarizer according to one embodiment of the present invention.

[0026] Figure 5 This is a partial enlarged rough cross-sectional view illustrating the adhesive layer in a polarizer according to another embodiment of the present invention.

[0027] Figure 6 This is a schematic cross-sectional view illustrating a polarizer with a phase difference layer according to one embodiment of the present invention.

[0028] Explanation of symbols 11. Polarizer 12 Surface treatment layer 13 Outer protective layer 14 Inner protective layer 20 Adhesive layers 21 Page 1 22 Page 2 23 End glue recessed surface 24 Adhesion Area 25 End glue recess 26 Through-hole adhesive recessed surface 27 Through-hole adhesive recess 30 Through Holes 40 phase difference layers 100 polarizer 110 Polarizing filter 120 polarizer 200 Polarizer with phase retardation layer Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. Furthermore, to make the description clearer, the drawings sometimes schematically represent the width, thickness, shape, etc., of various parts compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

[0030] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows.

[0031] (1) Refractive index (nx, ny, nz) “nx” is the refractive index in the direction where the refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0032] (2) In-plane phase difference (Re) “Re(λ)” is the in-plane phase difference measured at 23°C using light with a wavelength of λ nm. For example, “Re(550)” is the in-plane phase difference measured at 23°C using light with a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d.

[0033] (3) Phase difference in the thickness direction (Rth) “Rth(λ)” is the phase difference in the thickness direction of the film measured at 23°C using light with a wavelength of λ nm. For example, “Rth(550)” is the phase difference in the thickness direction of the film measured at 23°C using light with a wavelength of 550 nm. When the thickness of the film is set to d (nm), Rth(λ) is obtained by the formula: Rth = (nx - nz) × d.

[0034] (4) Nz coefficient The Nz coefficient is obtained by Nz=Rth / Re.

[0035] (5) Angle When referring to angles in this specification, the angle includes both clockwise and counterclockwise relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0036] A. Polarizing filter A-1. Overview of Polarizers Figure 1 This is a schematic plan view illustrating a polarizer according to one embodiment of the present invention. Figure 1 The polarizer 100 has a surface treatment layer 12, a polarizer 11 and an adhesive layer 20 in sequence.

[0037] In embodiments of the present invention, a through-hole 30 is typically formed in the polarizer 100. By forming a through-hole, for example in the case of an image display device with a built-in camera using a polarizer, the position of the camera can be aligned with the location where the through-hole is formed, thus preventing adverse effects on the camera's performance. The through-hole 30 can be formed at any suitable location depending on the purpose and the desired configuration of the image display device, preferably at or near the end of the polarizer. By forming a through-hole at or near the end of the polarizer, the impact on image display can be minimized when the polarizer is used in an image display device. The top view shape of the through-hole 30 can be any suitable shape (e.g., approximately circular, elliptical, triangular, quadrilateral, pentagonal, hexagonal, octagonal) depending on the purpose and the desired configuration of the image display device; a generally circular shape can be cited as a representative example. Multiple through-holes 30 may also be provided.

[0038] Figure 1 The polarizer 100, typically, has an end adhesive recess (gap) 25 formed in at least a portion of its end facing the inner side of the adhesive layer 20 in the polarizer's surface direction. The inventors have discovered that in polarizers like the one described above, adhesive from the adhesive layer may detach from the polarizer due to impacts during transport and operations during polarizer inspection, potentially causing problems with the operability and uniformity of the polarizer's quality. Furthermore, the inventors have conducted in-depth research into these problems and found that by forming an end adhesive recess in at least a portion of the end of the adhesive layer, adhesive detachment from the adhesive layer can be reduced, improving operability and quality uniformity, thus completing the present invention.

[0039] The maximum length in the plane direction of the polarizer in the end adhesive recess 25 is, for example, 50 μm or more, preferably 51 μm to 100 μm, more preferably 53 μm to 80 μm, and even more preferably 55 μm to 70 μm. If the maximum length in the plane direction of the polarizer in the end adhesive recess is within such a range, the aforementioned effects of the embodiments of the present invention can become more significant. It should be noted that the maximum length in the plane direction of the polarizer in the end adhesive recess can also be measured using an optical microscope by transmitted light, and calculated using an image captured by SEM as an auxiliary method.

[0040] Figure 2 This is a schematic cross-sectional view illustrating another embodiment of the polarizer of the present invention. Figure 2 The polarizer 110 has a through-hole adhesive recess (void) 27 formed in at least a portion of the outer periphery of the through-hole in the polarizer's surface direction, facing outwards from the through-hole. Due to the expanding applications of polarizers in recent years, the inventors have used polarizers in various environments and discovered that cracks sometimes occur at the outer periphery of the through-hole in the surface treatment layer when using polarizers with through-holes under harsh temperature conditions. The inventors have conducted in-depth research on suppressing such cracks and found that by forming a through-hole adhesive recess in at least a portion of the outer periphery of the through-hole in the adhesive layer, cracks that may occur at the outer periphery of the through-hole in the surface treatment layer can be suppressed, thus completing the present invention.

[0041] The maximum length in the plane direction of the polarizer in the through-hole adhesive recess 27 is, for example, 20 μm or more, preferably 25 μm to 100 μm, more preferably 30 μm to 80 μm, even more preferably 40 μm to 70 μm, and particularly preferably 50 μm to 60 μm. If the maximum length in the plane direction of the polarizer in the through-hole adhesive recess is within this range, the aforementioned effect becomes more significant. It should be noted that the maximum length in the plane direction of the polarizer in the through-hole adhesive recess can also be measured using an optical microscope by transmitted light, and calculated using an image captured by SEM as an auxiliary method.

[0042] Figure 3 This is a schematic cross-sectional view illustrating another embodiment of the polarizer of the present invention. (See diagram below.) Figure 3 As shown, depending on the purpose and desired configuration, the polarizer 120 may also have a first protective layer 13 (hereinafter sometimes referred to as the outer protective layer 13) between the surface treatment layer 12 and the polarizer 11, and / or may also have a second protective layer 14 (hereinafter sometimes referred to as the inner protective layer 14) between the polarizer 11 and the adhesive layer 20.

[0043] In embodiments of the present invention, the adhesive layer 20 is preferably configured as the outermost layer of the polarizer 100 (or the polarizer 200 with a phase retardation layer described later). With such a configuration, the generation of cracks in the periphery of the through-holes of the surface treatment layer can be further suppressed.

[0044] One side of the adhesive layer 20 is in contact with the polarizer 11 (or there may also be an inner protective layer 14 or a phase difference layer 40 described later). In order to make the other side of the adhesive layer 20 contact the panel or the like in the image forming apparatus, it can be protected by a peel-off pad (not shown) or the like.

[0045] It should be noted that the release liner, which is provided for the purpose of protecting the adhesive layer 20, and the panel of the image forming apparatus using a polarizer, are not included in the embodiments of the present invention. That is, the release liner and the panel are provided on the outside compared to the adhesive layer 20.

[0046] Polarizer 100 is typically a single sheet. Polarizer 100 has any suitable shape when viewed from the thickness direction. Examples of shapes for polarizer 100 viewed from the thickness direction include polygonal, circular, elliptical, and other irregular shapes; preferably, quadrilateral or irregular shapes; more preferably, rectangular or irregular shapes. In the case of a polygonal shape, polarizer 100 may also be an R-shape obtained by chamfering each vertex.

[0047] In the polarizer 100, a through-hole 30 is formed as described above. The diameter of the through-hole 30 is not particularly limited, but is preferably 10 mm or less, more preferably 1 mm to 8 mm, and even more preferably 2 mm to 6 mm. According to an embodiment of the present invention, even with such a small diameter through-hole, cracks in the outer periphery of the through-hole can be significantly suppressed.

[0048] When the polarizer 100 (polarizer 11, surface treatment layer 12, outer protective layer 13, inner protective layer 14) is rectangular, the length of the long side is, for example, 300mm to 400mm, or, for example, 100mm to 200mm, and the length of the short side is, for example, 200mm to 250mm, or, for example, 30mm to 100mm.

[0049] The following is a detailed explanation of the layers that make up the polarizer.

[0050] A-2. Polarizer As the polarizer 11, any suitable polarizer can be used. For example, the resin film forming the polarizer 11 can be a single-layer film or a laminate of two or more layers.

[0051] Specific examples of polarizers composed of single-layer resin films include polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films using dichroic substances such as iodine or dichroic organic dyes; and polyene-based oriented films such as dehydrated PVA products or dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA films with iodine and then uniaxially stretching them are preferred.

[0052] The aforementioned dyeing using iodine is performed, for example, by immersing the PVA membrane in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or simultaneously with dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA membrane may undergo swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA membrane in water for washing before dyeing, not only can stains and anti-blocking agents on the surface of the PVA membrane be washed away, but the PVA membrane can also swell to prevent uneven dyeing.

[0053] As a specific example of a polarizer obtained using a laminate, examples include a polarizer obtained using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate and allowing it to dry to form a PVA-based resin layer on the resin substrate, thus obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizer from the PVA-based resin layer.

[0054] Stretching typically involves immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may be further enhanced by air stretching the laminate at a high temperature (e.g., above 95°C) prior to stretching in the boric acid solution. By introducing assisted stretching, even when PVA is coated onto a thermoplastic resin, the crystallinity of PVA can be improved, resulting in high optical properties. Furthermore, by simultaneously improving the orientation of PVA beforehand, problems such as decreased orientation and dissolution of PVA can be prevented during subsequent dyeing and stretching processes when immersed in water, further achieving high optical properties. Moreover, when the PVA-based resin layer is immersed in a liquid, compared to cases where the PVA-based resin layer does not contain halides, the disorder of polyvinyl alcohol molecule orientation and the reduction of orientation can be suppressed. This improves the optical properties of the polarizer obtained through processing steps such as dyeing and underwater stretching in a liquid. Furthermore, by utilizing a drying shrinkage treatment to shrink the laminate along its width, optical properties can be further improved. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can also be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface for use. Detailed descriptions of such a polarizer manufacturing method are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

[0055] The thickness of the polarizer 11 is, for example, 1 μm to 25 μm, preferably 2 μm to 15 μm, more preferably 3 μm to 12 μm, even more preferably 4 μm to 10 μm, and particularly preferably 5 μm to 8 μm. If the thickness of the polarizer is within such a range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0056] The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of a single polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 45.5%, and more preferably 44.0% to 45.0%. It should be noted that the transmittance can be calculated, for example, as a Y-value measured using a 2-degree field of view (C-light source) according to JIS Z8701 and corrected for visibility.

[0057] The polarization degree of the polarizer is, for example, 95.0% or more, preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0058] A-3. Surface treatment layer The surface treatment layer 12 can be any suitable surface treatment layer depending on the application. Specific examples include a hard coating (HC) layer, an anti-reflective treatment layer, an anti-blocking treatment layer, and an anti-glare treatment layer.

[0059] The thickness of the surface treatment layer 12 is, for example, 1.0 μm or more, preferably 1.5 μm to 10 μm, more preferably 2.0 μm to 5.0 μm, and even more preferably 2.5 μm to 4.0 μm. If the thickness of the surface treatment layer is within such a range, fragility can be suppressed, and thus the generation of cracks in the surface treatment layer during the formation of through holes can be suppressed.

[0060] As surface treatment layer 12, a hard coating is preferably included. The hard coating (essentially a composition forming the hard coating) includes a curing component and, typically, a photopolymerization initiator. Examples of curing components include active energy ray-curable (meth)acrylates. Examples of active energy ray-curable (meth)acrylates include, for example, UV-curable (meth)acrylates and electron beam-curable (meth)acrylates. UV-curable (meth)acrylates are preferred because a hard coating can be formed efficiently through simple processing. UV-curable (meth)acrylates include UV-curable monomers, oligomers, polymers, etc. UV-curable (meth)acrylates include monomer components having preferably two or more, more preferably three to six UV-polymerizing functional groups, and oligomer components. Specific examples of UV-curable (meth)acrylates include urethane acrylates, pentaerythritol triacrylates, ethoxylated glycerol triacrylates, and polyether urethane diacrylates. UV-curable (meth)acrylates can be used alone or in combination of two or more. The curing method for the curing component can be either free radical polymerization or cationic polymerization. For example, a hard coating can be made by coating an outer protective layer with a UV-curable (meth)acrylate and then curing it by UV irradiation. The hard coating can be directly applied to the polarizer or the outer protective layer, or it can be transferred from a suitable substrate to the polarizer or the outer protective layer.

[0061] Any suitable additives can be added to the cured components. Examples of additives include ultraviolet absorbers, light stabilizers, and leveling agents. Ultraviolet absorbers and light stabilizers are preferred additives.

[0062] The constituent materials and methods for forming the hard coating are described, for example, in Japanese Patent Application Publication Nos. 2011-237789, 2020-064236, and 2010-152331. These publications are incorporated herein by reference. It should be noted that in this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid. Furthermore, (meth)acrylic acid is sometimes simply referred to as acrylic acid.

[0063] A-4. Adhesive layer As described above, the adhesive layer 20 typically has an end adhesive recess formed at least a portion of its end, preferably in the entire end of the adhesive layer 20, on the inner side of the adhesive layer 20 (the adhesive region 24 described later, with the end as the reference).

[0064] Figure 4 This is a partial enlarged rough cross-sectional view of the adhesive layer 20 in a polarizer according to one embodiment of the present invention. Figure 4 The adhesive layer 20 has a first surface 21, a second surface 22, and an end adhesive recessed surface 23. The first surface 21 of the adhesive layer 20 is a main surface in the thickness direction of the adhesive layer 20, and is the surface that contacts the polarizer 11 (or, in the case where the inner protective layer 14 or the phase difference layer 40 described later is also present). The second surface 22 of the adhesive layer 20 is another main surface in the thickness direction of the adhesive layer 20, and is the surface that contacts the panel or the like in the image forming apparatus. The end adhesive recessed surface 23 of the adhesive layer 20 is the outer peripheral end face in the surface direction of the adhesive layer 20, connecting the end peripheral portion of the first surface 21 to the end peripheral portion of the second surface 22.

[0065] The end adhesive recess 23 of the adhesive layer 20 is the end face of the outer peripheral side of the adhesive region 24, and in the plane direction of the polarizer, it is located inside the end faces of the outer peripheral sides of the polarizer 11, the inner protective layer 14, and the phase difference layer 40 described later. As a result, the end adhesive recess 25 is defined.

[0066] Figure 5 This is a partially enlarged, approximate cross-sectional view illustrating the adhesive layer in a polarizer according to another embodiment of the present invention. The shape of the end adhesive recessed surface 23 of the adhesive layer 20 can be any suitable shape. The shape of the end adhesive recessed surface 23 of the adhesive layer 20 is preferably as follows: Figure 5As shown, the length of the polarizer in the plane direction of the end adhesive recess 25 increases in the central region of the end (the region at the midpoint in the thickness direction of the end adhesive recess surface 23) compared to the layer interface (first surface 21 and second surface 22) in the plane direction of the adhesive layer 20. That is, the end adhesive recess surface 23 is shaped to be recessed inward in the plane direction from the layer interface toward the central region of the end. The shape of the end adhesive recess surface 23 of the adhesive layer 20 is more preferably a wedge-shaped shape that forms a pointed end from the end adhesive recess 25 toward the adhesive area 24. With such a configuration, adhesive detachment at the end can be further suppressed. It should be noted that the shape of such an adhesive layer in the thickness direction can also be observed using an optical microscope by transmitted light, supplemented by images taken with SEM.

[0067] The outer peripheral ends of the first surface 21 and the outer peripheral ends of the second surface 22 can be located at the same position relative to each other in the surface direction of the adhesive layer, or they can be positioned offset from each other in the surface direction.

[0068] The adhesive layer 20 faces the outside of the through hole in the direction of the polarizer (with the through hole as the reference for the adhesive area 24 side), and preferably forms a through hole adhesive recess in at least a portion of the outer periphery of the through hole, more preferably in the entire outer periphery of the through hole.

[0069] Adhesive layer 20 Figure 4 As shown, it further has a through-hole adhesive recess surface 26. The through-hole adhesive recess surface 26 of the adhesive layer 20 is the end face of the through-hole side in the surface direction of the adhesive layer 20, connecting the through-hole periphery of the first surface 21 to the through-hole periphery of the second surface 22.

[0070] The through-hole adhesive recess surface 26 of the adhesive layer 20 is the end face of the through-hole side of the adhesive region 24, and in the polarizer plane direction, it is located on the outer side from the through-hole, compared with the end faces of the polarizer 11, the inner protective layer 14, and the phase difference layer 40 (described later). As a result, the through-hole adhesive recess 27 is defined.

[0071] The shape of the through-hole adhesive recess surface 26 of the adhesive layer 20 can be any suitable shape. The shape of the through-hole adhesive recess surface 26 of the adhesive layer 20 is preferably as follows: Figure 5As shown, the length of the polarizer in the plane direction of the through-hole adhesive recess 27 is longer in the plane direction of the adhesive layer 20 than that of the layer interface (the region at the midpoint in the thickness direction of the through-hole adhesive recess surface 26). That is, the through-hole adhesive recess surface 26 is a shape that is recessed outward from the through-hole in the plane direction of the adhesive layer from the layer interface toward the central region of the through-hole. The shape of the through-hole adhesive recess surface 26 of the adhesive layer 20 is more preferably a wedge shape that forms a pointed end from the through-hole adhesive recess 27 toward the bonding region 24. With such a configuration, the stress of the adhesive layer can be mitigated even in the event of extreme temperature changes, thereby further suppressing cracks generated at the outer periphery of the through-hole in the surface treatment layer. It should be noted that such a shape in the thickness direction of the adhesive layer can also be observed using an optical microscope by transmitted light, supplemented by images taken with SEM.

[0072] The ends of the first surface 21 with through holes and the ends of the second surface 22 with through holes can be located at the same position relative to each other in the surface direction of the adhesive layer 20, or they can be positioned offset from each other in the surface direction.

[0073] The thickness of the adhesive layer 20 is, for example, 10 μm or more, preferably 15 μm to 50 μm, and more preferably 20 μm to 40 μm. If the thickness of the adhesive layer is within such a range, adhesive detachment at the ends can be suppressed, and furthermore, cracks generated at the periphery of the through holes in the surface treatment layer can be further suppressed.

[0074] The ratio of the maximum length of the end adhesive recess to the thickness of the adhesive layer is, for example, 1.70 to 5.00, preferably 2.00 to 4.00. If the ratio of the maximum length of the end adhesive recess to the thickness of the adhesive layer is within such a range, adhesive detachment at the end can be further suppressed.

[0075] The ratio of the maximum length of the through-hole adhesive recess to the thickness of the adhesive layer is, for example, greater than 1.60 and less than 3.10 or greater than 3.20 and less than 5.00, preferably greater than 1.65 and less than 3.00 or greater than 3.30 and less than 4.00. If the ratio of the maximum length of the through-hole adhesive recess to the thickness of the adhesive layer is within such a range, cracks generated at the periphery of the through-hole in the surface treatment layer can be further suppressed.

[0076] The adhesive layer 20 is composed of any suitable adhesive. Examples of adhesives include (meth)acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and proportion of monomers in the base resin forming the adhesive, as well as the amount of crosslinking agent, reaction temperature, and reaction time, an adhesive with desired properties corresponding to the purpose can be prepared.

[0077] The base resin of the adhesive can be used alone or in combination of two or more.

[0078] Among such adhesives, (meth)acrylic adhesives are preferred.

[0079] (Meth)acrylic adhesives typically contain a (meth)acrylic polymer as a base resin. The proportion of the (meth)acrylic polymer in the solids component of the (meth)acrylic adhesive is, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more.

[0080] The (meth)acrylic polymer has constituent units derived from (meth)acrylate alkyl esters. The content of the constituent units derived from (meth)acrylate alkyl esters is, for example, 80% by weight or more, preferably 90% by weight or more.

[0081] Alkyl groups that are alkyl groups of (meth)acrylates include, for example, straight-chain or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9, more preferably 3 to 6. Butyl acrylate is a preferred example of an alkyl (meth)acrylate.

[0082] (Meth)acrylate polymers may further have constituent units derived from monomers (comonomers) that can be copolymerized with alkyl (meth)acrylates. Examples of comonomers include, for example, carboxyl-containing monomers, hydroxyl-containing monomers, amide-containing monomers, aromatic (meth)acrylates, and heterocyclic vinyl monomers.

[0083] Representative examples of comonomers include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. 4-hydroxybutyl acrylate is preferred as the comonomer.

[0084] (Meth)acrylic adhesives preferably contain a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents.

[0085] (Meth)acrylic adhesives may also contain any suitable additives (e.g., silane coupling agents, adhesive imparting agents, polyether compounds, etc.).

[0086] Details of the adhesive layer or (meth)acrylic adhesive are described, for example, in Japanese Patent Application Publication No. 2006-183022, Japanese Patent Application Publication No. 2015-199942, Japanese Patent Application Publication No. 2018-053114, Japanese Patent Application Publication No. 2016-190996, International Publication No. 2018 / 008712, and Japanese Patent Application Publication No. 2014-115468, the contents of which are incorporated herein by reference.

[0087] The storage elastic modulus G' of the adhesive layer 20 at 25°C is, for example, 0.10 MPa or more, preferably 0.15 MPa to 5.0 MPa, and more preferably 0.20 MPa to 2.0 MPa. If the storage elastic modulus G' of the adhesive layer at 25°C is within the above range, crack initiation can be suppressed by inhibiting the stress applied to the peripheral end face and / or the end face of the through hole during dimensional shrinkage, while ensuring adhesive strength.

[0088] It should be noted that the storage elastic modulus G' of the adhesive layer is determined, for example, according to JIS K 6868 at a heating rate of 5°C / min and a frequency of 1Hz.

[0089] A-5. Protective Layer The polarizer 120 may have an outer protective layer 13 between the surface treatment layer 12 and the polarizer 11, as described above, and / or may have an inner protective layer 14 between the polarizer 11 and the adhesive layer 20. The outer protective layer 13 and the inner protective layer 14 may be laminated onto the polarizer through adhesive layers (specifically, adhesive layer, bonding agent layer), or they may be laminated tightly to the polarizer (without adhesive layers).

[0090] The outer protective layer 13 and the inner protective layer 14 are each composed of any suitable resin film that can be used as a protective film for the polarizer. Representative materials constituting the resin film include cellulose resins such as triacetyl cellulose (TAC), cyclic olefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. A representative example of a (meth)acrylic resin is a (meth)acrylic resin having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Application Publication Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005-146084. These publications are incorporated herein by reference. From the viewpoint of ease of processing irregular shapes, cellulose-based resins are preferred, and TAC is more preferred.

[0091] The thicknesses of the outer protective layer 13 and the inner protective layer 14 are, for example, 10 μm to 100 μm, preferably 12 μm to 50 μm, and more preferably 15 μm to 40 μm.

[0092] B. Polarizer with phase retardation layer Figure 6 This is a schematic cross-sectional view of a polarizer with a phase difference layer according to one embodiment of the present invention. Figure 6 The polarizer 200 with a phase retardation layer sequentially comprises a surface treatment layer 12, an outer protective layer 13, a polarizer 11, an inner protective layer 14, and an adhesive layer 20, and has a phase retardation layer 40 disposed between the inner protective layer 14 and the adhesive layer 20. That is, the polarizer 200 with a phase retardation layer is... Figure 3 The polarizer 120 has a phase retardation layer 40 disposed between the inner protective layer 14 and the adhesive layer 20. The phase retardation layer 40 is typically disposed on the inner protective layer 14 via an adhesive layer (not shown). The phase retardation layer 40 can typically be combined with a polarizer to provide circular or elliptical polarization functionality. It should be noted that, as another embodiment, the outer protective layer 13 and / or the inner protective layer 14 may be omitted.

[0093] The shape and size of the polarizer 200 with phase difference layer (phase difference layer 40) can correspond to the polarizer described in item A.

[0094] The retardation layer 40 can be a stretched film of a resin film (retardation film) or an alignment fixing layer of a liquid crystal compound (liquid crystal alignment fixing layer). A liquid crystal alignment fixing layer is preferred. By using a liquid crystal compound, the difference between nx and ny in the resulting retardation layer can be significantly increased compared to non-liquid crystal materials, thus significantly reducing the thickness of the retardation layer used to obtain the desired in-plane retardation. As a result, a significant reduction in the thinness of the polarizer with the retardation layer can be achieved. In this specification, "alignment fixing layer" refers to a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer, and its alignment state is fixed. It should be noted that "alignment fixing layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers. In the retardation layer, typically, rod-shaped liquid crystal compounds are aligned in a state aligned along the slow axis direction of the retardation layer (plane alignment). When the retardation layer is such a liquid crystal alignment fixing layer, by forming end adhesive recesses and through-hole adhesive recesses in the adhesive layer, adhesive detachment in the adhesive layer and the generation of cracks in the retardation layer can be suppressed. In particular, by forming through-hole adhesive recesses in the adhesive layer, the generation of cracks in the phase difference layer can be significantly suppressed.

[0095] The phase difference layer 40 can be a single layer or have a stacked structure (essentially a two-layer structure).

[0096] When the retardation layer is a single layer, it can typically function as a λ / 4 plate. Specifically, the Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 150 nm. The thickness of the retardation layer can be adjusted to achieve the desired in-plane phase difference for the λ / 4 plate. When the retardation layer is a stretched resin film, its thickness is, for example, 10 μm to 70 μm, preferably 30 μm to 55 μm. When the retardation layer is a liquid crystal alignment fixing layer, its thickness can be, for example, 1.0 μm to 2.5 μm, preferably 1.5 μm to 2.0 μm. In this embodiment, the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 46°. When the phase difference layer is a single layer, the phase difference layer preferably exhibits an inverse dispersion wavelength characteristic in which the phase difference value increases in proportion to the wavelength of the measurement light.

[0097] When the phase retardation layer is a stacked phase retardation layer with a stacked structure, the phase retardation layer typically has a two-layer structure (not shown) with a first phase retardation layer and a second phase retardation layer sequentially from the polarizer side. When the phase retardation layer has a stacked structure, typically both the first and second phase retardation layers are liquid crystal alignment fixing layers. The first phase retardation layer typically functions as a λ / 2 plate, and the second phase retardation layer typically functions as a λ / 4 plate. Specifically, the Re(550) of the first phase retardation layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm; the Re(550) of the second phase retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 150 nm. The thickness of the first phase retardation layer can be adjusted in a way that yields the desired in-plane phase retardation of the λ / 2 plate. The thickness of the first phase retardation layer is, for example, 1.5 μm to 4.0 μm, preferably 2.0 μm to 3.0 μm. The thickness of the second phase retardation layer can be adjusted in a way that yields the desired in-plane phase difference for the λ / 4 plate. The thickness of the second phase retardation layer is, for example, 0.5 μm to 2.5 μm, preferably 1.0 μm to 2.0 μm. In this embodiment, the angle between the slow axis of the first phase retardation layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 14° to 16°; the angle between the slow axis of the second phase retardation layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 74° to 76°. It should be noted that the arrangement order of the first and second phase retardation layers can also be reversed, and the angles between the slow axis of the first phase retardation layer and the absorption axis of the polarizer, and the angles between the slow axis of the second phase retardation layer and the absorption axis of the polarizer can also be reversed. When the phase difference layer has a stacked structure, each layer (e.g., the first phase difference layer and the second phase difference layer) can exhibit an inverse wavelength dispersion characteristic in which the phase difference value increases in accordance with the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the phase difference value decreases in accordance with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the phase difference value remains essentially unchanged according to the wavelength of the measurement light.

[0098] The retardation layer (in the case of a stacked structure, each layer) can be a retardation layer exhibiting a relationship of arbitrarily suitable refractive index characteristics. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 1.0 to 1.3.

[0099] Furthermore, in the case where the phase retardation layer is a single layer or a stacked structure, another phase retardation layer (so-called positive C-plate: not shown) with refractive index characteristics showing the relationship nz>nx=ny can be set between the phase retardation layer 40 and the adhesive layer 20.

[0100] C. Manufacturing methods of polarizers and polarizers with phase retardation layers C-1. Overview of the manufacturing methods of polarizers and polarizers with phase retardation layers A method for manufacturing a polarizer according to one embodiment of the present invention includes: a lamination step of sequentially laminating the surface treatment layer described in item A-3, the polarizer described in item A-2, and the adhesive layer described in item A-4 to obtain an elongated optical laminate; a punching step of punching the elongated optical laminate into a rectangular shape using a first processing tool; an end processing step of cutting the ends of the optical laminate using a second processing tool; and a through-hole forming step of forming the through-hole described above in the optical laminate using a third processing tool. As a method for manufacturing a polarizer, it is preferable to perform each step in the order described above.

[0101] In the aforementioned end-processing steps, typically, a clamping force of 1000 N or more is applied to the optical laminate along its thickness direction, and the tool angle of the second machining cutter is 25° or more. If the cutting conditions in the end-processing steps are within such a range, an end-adhesive recess can be appropriately formed, further suppressing adhesive detachment at the ends.

[0102] In the above-described through-hole forming process, a clamping force of 1000 N or more is applied to the optical laminate along its thickness direction, and the tool angle of the third machining tool is 25° or more; or a clamping force of 2000 N or more is applied to the optical laminate along its thickness direction, and the tool angle of the second machining tool is 15° or more. If the cutting conditions in the through-hole forming process are within such a range, a through-hole adhesive recess that can suppress cracks at the outer periphery of the through-hole can be suitably formed.

[0103] The following is a detailed explanation of each step in a representative example of a method for manufacturing polarizers and polarizers with phase retardation layers.

[0104] C-2. Lamination process In a typical example, the lamination process involves sequentially stacking the surface treatment layer 12, the polarizer 11, and the adhesive layer 20 to obtain a strip-shaped optical laminate.

[0105] Any suitable method can be used to stack the layers.

[0106] The polarizer 200 with a phase retardation layer can be manufactured by simply stacking the phase retardation layer 40 between the polarizer 11 (which is the inner protective layer 14 when it has an inner protective layer 14) and the adhesive layer 20.

[0107] The following, referred to as an optical stack, also includes optical stacks with a phase difference layer.

[0108] C-3. Blanking process The punching process uses the first processing blade to punch the above-mentioned long strip-shaped optical laminate into any suitable shape.

[0109] Specifically, optical laminates can be cut into rectangular shapes, shapes similar to rectangles, or shapes appropriate to the purpose (e.g., circles).

[0110] Examples of primary cutting tools include Thomson knives and Pinnacle (registered trademark) knives.

[0111] C-4. End-processing procedures The end-processing step uses a second processing tool to cut the ends of the optical laminate.

[0112] In the end-processing process, multiple optical laminates that have been cut into any suitable shape in the punching process are first stacked to form a workpiece.

[0113] The workpiece has opposing outer peripheral surfaces (cutting surfaces) and orthogonal outer peripheral surfaces (cutting faces). The workpiece is clamped from above and below, for example, using a clamping mechanism (e.g., a jig). The clamping mechanism can be made of a soft material or a hard material. When the clamping mechanism is made of a soft material, its hardness (JISA) is, for example, 60° to 80°. If the hardness of the clamping mechanism is too high, indentations may sometimes remain due to the clamping mechanism; if the hardness of the clamping mechanism is too low, misalignment may sometimes occur due to jig deformation, resulting in insufficient cutting accuracy.

[0114] The total thickness of the workpiece is, for example, 1.0 mm to 20 mm, preferably 1.5 mm to 8.0 mm. The number of optical laminates constituting the workpiece can be, for example, 20 to 100 pieces.

[0115] Next, while applying a clamping force to the workpiece clamped by the clamping mechanism, the end of the optical laminate, i.e. the outer peripheral surface of the workpiece, is cut at a predetermined position using the second machining tool.

[0116] The clamping force can be applied using a clamping mechanism or through a clamping mechanism, such as using a vise-like clamp to apply the clamping force.

[0117] The clamping force in the end-treatment process is typically 1000N or more, preferably 2000N to 4000N, and more preferably 2500N to 3500N. If the clamping force in the end-treatment process is within this range, an end glue recess can be appropriately formed, which can further suppress glue detachment at the end.

[0118] As a second machining tool, an end mill can be cited as an example.

[0119] An end mill has a body that rotates around a pivot axis and a cutting tool that protrudes from the body and is defined as its outermost diameter. The body can be configured in any suitable way. The number of cutting tools can be appropriately set. Examples of materials for the cutting tool include superhard alloys and high-speed steels, with superhard alloys being preferred. The Vickers hardness (HV hardness) of the cutting tool is, for example, 800 to 2500, preferably 1500 to 1900.

[0120] The cutting tool of an end mill can be set to any suitable configuration.

[0121] The cutting tool angle (torsion angle) of the end mill in the end-processing step is typically 25° or more, preferably 30° to 45°, and more preferably 35° to 40°. If the cutting tool angle of the end mill in the end-processing step (the cutting tool angle of the second machining tool) is within such a range, an end-grip recess that improves operability and uniformity can be appropriately formed.

[0122] The end mill is held by the working machine and rotates at high speed around its axis of rotation. It is then fed out in a direction intersecting the axis of rotation, while the cutting edge of the end mill comes into contact with and cuts into the outer circumferential surface of the workpiece. In other words, cutting the end of the workpiece (optical laminate) is typically performed by having the cutting edge of the end mill come into contact with and cut into the workpiece.

[0123] A typical end mill can rotate about an axis parallel to the stacking direction of the optical laminate. The direction of rotation can be clockwise or counterclockwise (see top view). During the end-processing step, the end mill rotates at a certain speed. The rotation speed is, for example, 300 rpm to 100,000 rpm, preferably 500 rpm to 50,000 rpm.

[0124] As described above, the end mill can rotate while moving relative to the workpiece supported by the clamping mechanism. The end mill can be moved with the workpiece fixed in the clamping mechanism, or the workpiece can be moved with the end mill fixed. In one embodiment, the end mill moves in one direction around the workpiece, which is fixed in the clamping mechanism, at a feed rate described below, cutting the entire end face of the workpiece.

[0125] The cutting conditions in the end-processing steps can be appropriately set according to the composition of the workpiece (optical laminate), the desired shape, etc. Cutting can include roughing and finishing. The depth of cut for both roughing and finishing can be set to any suitable depth. The number of cuts for both roughing and finishing can be set to any suitable number.

[0126] The feed rate (relative movement speed of the end mill relative to the cutting surface of the workpiece) in the end-processing step is, for example, 10 mm / min to 5000 mm / min, preferably 50 mm / min to 3500 mm / min.

[0127] After the workpiece is cut, by releasing the workpiece from the clamping force, an end glue recess 25 can be formed in the adhesive layer 20.

[0128] C-5. Through-hole forming process In the through-hole forming process of one embodiment of the present invention, a through-hole is formed in the optical laminate using a third processing tool.

[0129] In the through-hole forming process, the end-treated workpiece (optical laminate) is clamped by a clamping mechanism. While applying a clamping force, the through-hole forming position on the surface of the optical laminate is cut by a third machining tool to form a through hole.

[0130] The clamping force can be applied using a clamping mechanism or through a clamping mechanism, similar to the end processing step in item C-4 above, for example, by using a vise-shaped clamp to apply the clamping force.

[0131] The clamping force in the through-hole forming process is typically 1000N or more, preferably 2000N to 4000N, and more preferably 2500N to 3500N. If the clamping force in the through-hole forming process is within this range, a through-hole adhesive recess can be suitably formed, which can suitably form a through-hole adhesive recess that can suppress cracks at the outer periphery of the through-hole.

[0132] Examples of third machining tools include end mills, Thomson cutters, and Pinnacle (registered trademark) cutters, with end mills being preferred. Alternatively, the same machining tool as the second machining tool described above can be used as the third machining tool.

[0133] The following is a representative example of the formation of a through hole when the third machining tool is an end mill.

[0134] First, a lower hole is formed at the location where the through hole is formed on the workpiece, parallel to the stacking direction of the optical laminate. In this specification, "lower hole" refers to a hole that serves as a gripper for forming the through hole in a precise location. The lower hole is formed, for example, by cutting with an end mill that holds the upper end from top to bottom. The diameter of the lower hole is substantially the same as the outer diameter of the end mill.

[0135] Next, while cutting with the end mill in contact with the end face of the lower hole, the end mill is moved around the end face of the lower hole for one revolution. The result is the formation of a next hole with a diameter a specified amount larger than the diameter of the lower hole. The same steps as forming the next hole are then repeated to form a through hole with the desired diameter. If necessary, the end face of the through hole can also be subjected to finish cutting.

[0136] The cutting conditions in the through hole forming process can be appropriately set according to the diameter of the through hole, the outer diameter of the end mill, and the number of revolutions of the end mill.

[0137] The cutting tool angle (torsion angle) of the end mill in the through-hole forming process is typically 15° or more, preferably 20° to 40°, and more preferably 25° to 35°. If the cutting tool angle of the end mill in the through-hole forming process (the cutting tool angle of the third machining tool) is within such a range, a through-hole adhesive recess that can suppress cracks at the outer periphery of the through hole can be suitably formed.

[0138] In the through-hole forming process, the end mill rotates at a certain speed. The rotation speed of the end mill is, for example, 300 rpm to 100,000 rpm, preferably 500 rpm to 50,000 rpm.

[0139] The feed rate (relative movement speed of the end mill relative to the cutting surface of the workpiece) in the through hole forming process is, for example, 10 mm / min to 5000 mm / min, preferably 50 mm / min to 3500 mm / min.

[0140] After the workpiece is cut, by releasing the workpiece from the clamping force, a through-hole adhesive recess 27 can be formed in the adhesive layer 20.

[0141] Thus, the polarizer and the polarizer with phase difference layer of the present invention are obtained.

[0142] Example The present invention will now be specifically described through examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows. Furthermore, unless otherwise specified, "parts" and "%" in the examples are based on weight. It should be noted that the methods for measuring and evaluating each characteristic are as follows.

[0143] (1) Determination of thickness Thicknesses below 10 μm were measured using an interferometric film thickness gauge (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name "KC-351C").

[0144] (2) Determination of the storage elastic modulus G' of the adhesive layer The storage elastic modulus G' of the adhesive layer at 25°C was determined according to JIS K6868 at a heating rate of 5°C / min and a frequency of 1Hz.

[0145] (3) Determination of the maximum length of the end glue recess The ends of the polarizers with phase retardation layers obtained in the examples and comparative examples were observed from the polarizer side using an optical microscope (product name "MX63", manufactured by Olympus Corporation) with transmitted light. The distance from the end of the polarizer (phase retardation layer) to the end of the adhesive layer (the most concave part in the thickness direction of the adhesive layer) in the surface direction of the polarizer was measured as the maximum length of the end adhesive recess.

[0146] (4) Determination of the maximum length of the through hole adhesive recess The through-hole portion of the polarizer with phase retardation layer obtained in the examples and comparative examples was observed from the polarizer side by irradiating transmitted light using an optical microscope (product name "MX63", manufactured by Olympus). The distance from the end of the polarizer (phase retardation layer) to the end of the adhesive layer (the most concave part in the thickness direction of the adhesive layer) in the plane direction of the polarizer was measured as the maximum length of the through-hole adhesive recess.

[0147] (5) Evaluation of the maximum length of adhesive detachment at the end of the adhesive layer The polarizers with phase retardation layers obtained in the examples and comparative examples were individually packaged and stored at room temperature for 24 hours. After that, the packages were opened, and transmitted light was irradiated using an optical microscope (product name "MX63", manufactured by Olympus). The ends of the polarizers with phase retardation layers were observed from the polarizer side. For any identifiable areas of adhesive detachment, the distance from the end of the adhesive layer of the polarizer with phase retardation layers to the end of the detached area (the most detached part) was measured and used as the maximum length of the detached area. The following evaluation was conducted.

[0148] “〇”: The maximum length of the detached portion of the adhesive is less than 50μm.

[0149] “△”: The maximum length of the detached portion of the adhesive is more than 50μm and less than 200μm.

[0150] "×": The maximum length of the detached portion of the adhesive is over 200μm.

[0151] (6) Evaluation of cracks The polarizers with phase retardation layers obtained in the examples and comparative examples were bonded to a glass plate. After bonding, they were subjected to a thermal shock test of -40°C to 80°C for 300 cycles. Subsequently, using an optical microscope (product name "MX63", manufactured by Olympus), transmitted light was irradiated, and the through-hole portion was observed from the polarizer side. The number of cracks generated and the length of the generated cracks were measured, and the evaluation was carried out as follows.

[0152] "◎": The crack length is less than 100μm and the number of cracks generated is less than 10.

[0153] “〇”: The length of the crack is less than 100μm and the number of cracks is more than 10.

[0154] “△”: The length of the crack is greater than 100μm and less than 200μm.

[0155] "×": The crack length is more than 200μm.

[0156] <Manufacturing Example 1: Fabrication of Outer Protective Layer and Surface Treatment Layer> A monomer composition was obtained by mixing a multifunctional acrylate (trade name "Viscoat#300", manufactured by Osaka Organic Chemical Co., Ltd.) with pentaerythritol triacrylate as the main component, a photopolymerization initiator (trade name "Omnirad184", manufactured by IGM Resins), an ultraviolet absorber (trade names "Tinuvin477" and "Tinuvin970", manufactured by BASF) and a light stabilizer (trade name "Tinuvin249", manufactured by BASF).

[0157] The obtained monomer composition was coated on one side of a substrate (a cyclic olefin film (trade name "ZEONOR (registered trademark)", manufactured by ZEONCORPORATION, 25 μm thick), dried at 90°C for 1 minute, and then irradiated with 300 mJ / cm². 2 The coating is cured by ultraviolet light, forming a resin layer (surface treatment layer), resulting in an outer protective layer (25 μm thick) of cyclic olefin film and a surface treatment layer of acrylic resin (hard coating, 2.5 μm thick).

[0158] <Manufacturing Example 2: Preparation of Adhesive Composition A> In a reaction vessel equipped with a cooling pipe, a nitrogen inlet pipe, a thermometer, and a stirring device, a monomer mixture containing 76.1 parts by weight of butyl acrylate and 0.1 parts by weight of 4-hydroxybutyl acrylate was added. Then, relative to 100 parts by weight of the monomer mixture (solid component), 0.3 parts by weight of 2,2'-azobisisobutyronitrile (2,2'-DIS) as a polymerization initiator was added together with 100 parts by weight of ethyl acetate. Under a nitrogen flow, the liquid temperature in the flask was maintained at 60°C for 4 hours to obtain a solution A of an acrylic polymer with a weight-average molecular weight (Mw) of 2.2 million. Relative to 100 parts by weight of the solid component of the obtained acrylic polymer solution A, 0.6 parts by weight of an isocyanate crosslinking agent (trade name "Takenate D101E", trimethylolpropane / toluene diisocyanate adduct, manufactured by Mitsui Chemicals) and 0.04 parts by weight of an epoxy-containing silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain an adhesive composition A.

[0159] <Manufacturing Example 3: Preparation of Adhesive Composition B> The amount of the isocyanate-based crosslinking agent was increased from 0.6 parts by weight to 2.5 parts by weight, and 1 part by weight of a polyether compound with reactive silyl groups (trade name "SILYL SAT10", manufactured by KANEKA) was added. Otherwise, the same procedure as in Manufacturing Example 2 was followed to obtain adhesive composition B.

[0160] <Manufacturing Example 4: Preparation of Adhesive Composition C> The amount of the isocyanate-based crosslinking agent was increased from 0.6 parts by weight to 12 parts by weight, and 1 part by weight of a polyether compound with reactive silyl groups (trade name "SILYL SAT10", manufactured by KANEKA) was added. Otherwise, the same procedure as in Manufacturing Example 2 was followed to obtain adhesive composition C.

[0161] <Manufacturing Example 5: Formation of Liquid Crystal Alignment Fixing Layer A> A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242", chemical formula below) was dissolved in cyclopentanone to prepare a solution with a solid content of 20% by weight.

[0162] [Chemical Formula 1] A liquid crystal coating solution was prepared by adding a surfactant (BYK-Chemie, "BYK-361N") and a photopolymerization initiator (IGM Resins, "Omnirad 907") to the solution. The amount of surfactant added was 0.5 parts by weight relative to 100 parts by weight of the photopolymerizable liquid crystal compound. Furthermore, the amount of photopolymerization initiator added was 5 parts by weight relative to 100 parts by weight of the photopolymerizable liquid crystal compound.

[0163] Furthermore, as the alignment substrate, an elongated polyethylene terephthalate (PET) film (38 μm thick) was rubbed with a friction cloth to perform an alignment treatment. The direction of the alignment treatment was set such that it forms a 15° angle with respect to the absorption axis of the polarizer when viewed from the visual recognition side when bonded to the polarizer. In other words, the angle between the elongated direction of the alignment substrate and the direction of the alignment treatment is 15°.

[0164] Next, the liquid crystal coating liquid described above was applied to the oriented surface using a bar coater, and the liquid crystal compound was oriented by heating and drying at 100°C for 3 minutes. After cooling the liquid crystal layer formed in this manner to room temperature (25°C), it was irradiated with a cumulative light intensity of 400 mJ / cm under a nitrogen atmosphere. 2 Ultraviolet light is used to cure the liquid crystal layer. This forms a liquid crystal alignment fixing layer A on the alignment substrate. The liquid crystal alignment fixing layer A is elongated and has a thickness of 2.0 μm.

[0165] The liquid crystal alignment fixing layer A has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer A, the in-plane phase difference Re (550) is 240 nm, and the phase difference Rth (550) in the thickness direction is 240 nm. That is, the liquid crystal alignment fixing layer A can function as a λ / 2 plate.

[0166] <Manufacturing Example 6: Formation of Liquid Crystal Alignment Fixing Layer B> The orientation treatment direction was changed so that it was 75° relative to the absorption axis direction of the polarizer (the long strip direction of the orientation substrate) when viewed from the visual recognition side, and the coating thickness was also changed. Otherwise, the same procedure as in Manufacturing Example 5 was followed to form a liquid crystal alignment fixing layer B on the orientation substrate. The thickness of the liquid crystal alignment fixing layer B was 1.0 μm.

[0167] The liquid crystal alignment fixing layer B has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer B, the in-plane phase difference Re(550) is 120 nm, and the phase difference Rth(550) in the thickness direction is also 120 nm. That is, this liquid crystal alignment fixing layer B can function as a λ / 4 plate.

[0168] <Manufacturing Example 7: Fabrication of Stacked Phase Difference Layers> The liquid crystal alignment fixing layer A obtained in Manufacturing Example 5 is used as the first phase difference layer (i.e., the first liquid crystal alignment fixing layer), and the liquid crystal alignment fixing layer B obtained in Manufacturing Example 6 is used as the second phase difference layer (i.e., the second liquid crystal alignment fixing layer).

[0169] The surfaces of the first liquid crystal alignment layer obtained in Manufacturing Example 5 and the second liquid crystal alignment layer obtained in Manufacturing Example 6 were treated with a corona treatment machine at a density of 50 W·min / m. 2 Perform corona treatment.

[0170] Next, while conveying the first liquid crystal alignment fixing layer along the long strip direction, an acrylic UV-curable adhesive is applied to the corona-treated surface of the first liquid crystal alignment fixing layer using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed 130% / relative line speed) to form a coating film on the first liquid crystal alignment fixing layer.

[0171] In addition, following the same procedure as described above, an acrylic UV-curable adhesive is applied to the corona-treated surface of the second liquid crystal alignment fixing layer.

[0172] Next, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer are bonded together using a bonding mill in such a way that their longitudinal directions become substantially parallel. More specifically, the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer are passed through the bonding mill such that the coatings on the first liquid crystal alignment fixing layer and the coatings on the second liquid crystal alignment fixing layer are in contact with each other. The linear speed of each of the first and second liquid crystal alignment fixing layers is 15 m / min. At this time, the angle between the slow axis direction of the first liquid crystal alignment fixing layer and the slow axis direction of the second liquid crystal alignment fixing layer is 60°.

[0173] Then, the coating is irradiated with ultraviolet light to cure the acrylic UV-curable adhesive, forming an acrylic UV-curable adhesive layer (thickness: 5μm).

[0174] Next, the alignment substrate is peeled off from the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer respectively.

[0175] Thus, a stacked phase retardation layer with a stacked structure of a first liquid crystal alignment fixing layer / acrylic UV-curable adhesive layer / second liquid crystal alignment fixing layer is fabricated.

[0176] <Example 1> As a polarizer, a film (5 μm thick) is used, which is obtained by uniaxially stretching a strip of polyvinyl alcohol (PVA)-based resin film containing iodine along its length (MD direction). The outer protective layer and surface treatment layer obtained in Manufacturing Example 1 are bonded to one side of this polarizer. It should be noted that the bonding is performed in such a way that the outer protective layer is on the polarizer side.

[0177] An inner protective layer (TAC film (thickness 25 μm)) is attached to the other side of the polarizer. An adhesive layer (thickness 1 μm) is used to attach the other side of the inner protective layer to the surface of the first liquid crystal alignment fixing layer of the stacked phase retardation layer obtained in Manufacturing Example 7. Furthermore, an adhesive layer (thickness 15 μm) is formed on the other side of the stacked phase retardation layer (the side of the second liquid crystal alignment fixing layer) using adhesive composition A from Manufacturing Example 2, resulting in a strip-shaped optical laminate with the adhesive layer as the outermost layer.

[0178] The long strip of optical laminate is punched into a rectangular shape with dimensions of 200mm in length and 300mm in width. At this time, the punching is performed with the absorption axis of the polarizer in the direction of the shorter side.

[0179] Next, 100 blanked optical laminates are stacked along the stacking direction of each layer to form a workpiece. The workpiece is held in place from top to bottom along the stacking direction using a vise-like clamp with a clamping force of 1500N. The cutting edge of the end mill is set to 30°, and the outer circumferential surface of the workpiece is cut. It should be noted that the feed rate of the end mill is 250 mm / min, and the rotational speed is 4000 rpm.

[0180] Furthermore, while maintaining the clamping force of 1500N on the optical laminate, the cutting angle of the end mill was changed to 20°, and a 2mm diameter through hole was formed at a position 5mm from the long side and 150mm from the short side of the workpiece. It should be noted that the end mill's feed rate was 500mm / min and its rotational speed was 2500rpm.

[0181] As a result, at the end of the adhesive layer of the obtained polarizer with phase retardation layer, an end adhesive recess with a maximum length of 50 μm from the end of the phase retardation layer in the outer periphery of the end is formed, and a through hole adhesive recess with a maximum length of 14 μm from the end of the through hole in the outer periphery of the adhesive layer of the polarizer with phase retardation layer is formed in the outer periphery of the through hole of the polarizer with phase retardation layer in the outer periphery of the adhesive layer.

[0182] The length of the polarizer in the end adhesive recess in the planar direction is longer in the central region of the end compared to the layer interface (first and second surfaces) in the planar direction of the adhesive layer. The length of the polarizer in the through hole adhesive recess in the planar direction is longer in the central region of the through hole compared to the layer interface (first and second surfaces) in the planar direction of the adhesive layer.

[0183] By operating in this way, a polarizer with a phase difference layer is produced, which has end adhesive recesses and through-hole adhesive recesses in the adhesive layer.

[0184] The peeling and cracking of the adhesive in the obtained polarizer with phase retardation layer were evaluated using the above evaluation method, and are shown in Table 1 together with the structure and cutting conditions of the polarizer with phase retardation layer.

[0185] <Examples 2-40 and Comparative Examples 1-16> Except for changing the structure and cutting conditions as described in Tables 1-4, the polarizer with a phase retardation layer was manufactured in the same manner as in Example 1. The peeling and cracking of the adhesive in the obtained polarizer with a phase retardation layer were evaluated in the same manner as in Example 1 and are shown in Tables 1-4.

[0186] <Evaluation> As shown by the comparison between Examples 1-6 and Comparative Examples 1-4 in Table 1, and between Examples 21-26 and Comparative Examples 9-12 in Table 3, the polarizers of the embodiments of the present invention significantly suppressed the detachment of adhesive at the ends of the adhesive layer. Furthermore, as shown by the comparison between Examples 7-20 and Comparative Examples 5-8 in Table 2, and between Examples 27-40 and Comparative Examples 13-16 in Table 4, the detachment of adhesive at the ends of the adhesive layer was significantly suppressed, and the formation of cracks in the through-hole portion after the thermal shock test was also significantly suppressed.

[0187] Industrial availability The polarizer of the present invention, the polarizer with a phase difference layer, and the polarizer obtained by the polarizer manufacturing method can be suitably used in image display devices, etc.

Claims

1. A polarizer comprising, sequentially having a surface treatment layer, a polarizer, and an adhesive layer, and having a through-hole formed therein, In the planar direction of the polarizer, an end adhesive recess is formed in at least a portion of the end of the adhesive layer. The maximum length of the end adhesive recess in the plane direction of the polarizer is more than 50 μm.

2. The polarizer according to claim 1, wherein, A through-hole adhesive recess is formed in at least a portion of the outer periphery of the through-hole in the adhesive layer. The maximum length of the through-hole adhesive recess in the plane direction of the polarizer is more than 20 μm.

3. The polarizer according to claim 1 or 2, wherein, The adhesive layer is configured as the outermost layer.

4. The polarizer according to claim 2, wherein, The length of the through-hole adhesive recess in the plane direction of the polarizer is longer in the central region in the thickness direction of the adhesive layer compared to the layer interface.

5. The polarizer according to claim 1 or 2, wherein, A protective layer is provided between the surface treatment layer and the polarizer.

6. The polarizer according to claim 1 or 2, wherein, The storage elastic modulus G' of the adhesive layer at 25°C is greater than or equal to 0.10 MPa.

7. The polarizer according to claim 1 or 2, wherein, The thickness of the surface treatment layer is 1.0 μm or more.

8. The polarizer according to claim 1 or 2, wherein, The thickness of the adhesive layer is 15 μm or more.

9. The polarizer according to claim 1 or 2, wherein, The diameter of the through hole is 2 mm or more.

10. A polarizer with a phase retardation layer, comprising the polarizer of claim 1 or 2 with a phase retardation layer. A phase difference layer is provided between the polarizer and the adhesive layer.

11. A manufacturing method, comprising the method for manufacturing the polarizer according to claim 1, comprising: A lamination process in which the surface treatment layer, the polarizer, and the adhesive layer are sequentially stacked to obtain a strip-shaped optical laminate; The punching process involves using the first processing cutter to punch the long strip of optical laminate into a rectangular shape. An end-processing step that uses a second cutting tool to cut the end of the optical laminate; The through-hole forming process involves forming the through-hole in the optical laminate using a third processing tool. In this end-processing step, a clamping force of 1000N or more is applied to the optical laminate along the thickness direction, and the tool angle of the second processing tool is 25° or more.

12. The manufacturing method according to claim 11, wherein, In the end processing step, a clamping force of 2000N or more is applied to the optical laminate along the thickness direction.

13. The manufacturing method according to claim 11 or 12, wherein, In the through-hole forming process, A clamping force of 1000 N or more is applied to the optical laminate along its thickness direction, and the tool angle of the third machining tool is 25° or more. Alternatively, a clamping force of 2000 N or more is applied to the optical laminate along its thickness direction, and the tool angle of the third machining tool is 15° or more.

14. The manufacturing method according to claim 13, wherein, In the through-hole forming process, a clamping force of 1000N or more is applied to the optical laminate along the thickness direction of the optical laminate, and the tool angle of the third processing tool is 25° or more.

15. The manufacturing method according to claim 14, wherein, In the through-hole forming process, a clamping force of 2000N or more is applied to the optical laminate along the thickness direction of the optical laminate.

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