Polarizing plate with hard coat layer and image display device comprising the same

Abstract

To provide a polarizing plate with a hard coat layer, which significantly suppresses chipping and cracking of the hard coat layer in a deformed portion.SOLUTION: A polarizing plate with a hard coat layer according to an embodiment of the present invention comprises a polarizer, a protective layer, an intermediate layer having a thickness of 0.1-8 μm, and a hard coat layer having a thickness of 5 μm or less arranged in the described order, and includes a non-rectangular deformed portion. The intermediate layer has a shear fracture strength of 10 MPa or greater per 1 μm of thickness.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a hard coat layer and an image display device including the polarizing plate with a hard coat layer. [Background technology]

[0002] Polarizing plates are widely used in image display devices such as mobile phones and notebook personal computers to realize image display and / or improve the performance of the image display. When the surface of an image display device is scratched by external contact, the visibility of the displayed image may be reduced. For this reason, polarizing plates (hard-coated polarizing plates) having a hard coat layer formed on the front side (viewing side) may be used to protect the surface of the image display device. In recent years, there has been a demand for optical films to be processed into shapes other than rectangular (deformed shapes: for example, the formation of notches and / or through holes). However, there is a problem in that chips and / or cracks are likely to occur in the hard coat layer in the deformed areas of hard-coated polarizing plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-234163 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a polarizing plate with a hard coat layer in which chipping and cracking of the hard coat layer in the irregularly shaped processed portion are significantly suppressed. [Means for solving the problem]

[0005] A polarizing plate with a hard coat layer according to an embodiment of the present invention comprises a polarizer, a protective layer, an intermediate layer having a thickness of 0.1 μm to 8 μm, and a hard coat layer, in this order, and has an irregular shape other than rectangular, and the shear fracture strength per μm of the thickness of the intermediate layer is 10 MPa or more. In one embodiment, the intermediate layer is a compatible region containing a component of the hard coat layer and a component of the protective layer. In one embodiment, the intermediate layer has a thickness of 0.3 μm to 5 μm. In one embodiment, the intermediate layer has a shear fracture strength per 1 μm of thickness of 14 MPa or more. In one embodiment, the hard coat layer has a thickness of 5 μm or less. In one embodiment, the protective layer is made of a triacetyl cellulose film. In one embodiment, the irregular shape is selected from the group consisting of a through hole, a V-shaped notch, a U-shaped notch, a recess that resembles a boat shape when viewed in a plan view, a rectangular recess that resembles a bathtub shape when viewed in a plan view, and combinations thereof. According to another aspect of the present invention, there is provided an image display device, which includes the above-mentioned hard coat layer-attached polarizing plate on the viewing side. [Effects of the Invention]

[0006] According to an embodiment of the present invention, in a polarizing plate with a hard coat layer having an irregular shape (irregularly processed portion) other than rectangular, an intermediate layer, which is typically a compatible region, is formed between the protective layer and the hard coat layer, and the thickness and shear fracture strength per unit thickness of the intermediate layer are optimized, thereby realizing a polarizing plate with a hard coat layer in which chipping and cracking of the hard coat layer in the irregularly processed portion are significantly suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view of a polarizing plate with a hard coat layer according to one embodiment of the present invention. [Figure 2]FIG. 2 is a schematic diagram for explaining a specific procedure for determining shear fracture strength. [Figure 3] FIG. 2 is a schematic plan view illustrating an example of an irregular shape or irregularly processed portion in a polarizing plate with a hard coat layer according to an embodiment of the present invention. [Figure 4] 10A and 10B are schematic plan views illustrating modified examples of irregular shapes or irregularly processed portions in a polarizing plate with a hard coat layer according to an embodiment of the present invention. [Figure 5] FIG. 10 is a schematic plan view illustrating another modified example of the irregular shape or irregularly processed portion in the hard coat layer-attached polarizing plate according to the embodiment of the present invention. [Figure 6] FIG. 10 is a schematic plan view illustrating another modified example of the irregular shape or irregularly processed portion in the hard coat layer-attached polarizing plate according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Note that the drawings are schematic for clarity, and the ratios of length, width, thickness, etc., as well as angles, etc., in the drawings are different from the actual ones.

[0009] In this specification, the term "hard coat layer" is used as a general term for a hard surface treatment layer having a surface protection function. Therefore, the hard coat layer may include not only a general hard coat layer but also an anti-reflection layer, an anti-sticking layer, an anti-glare layer, and an anti-blocking layer.

[0010] A. Overview of polarizing plate with hard coat layer FIG. 1 is a schematic cross-sectional view of a hard coat layer-attached polarizing plate according to one embodiment of the present invention. The hard coat layer-attached polarizing plate 100 shown in the figure has, in this order, a polarizer 10, a protective layer 20, an intermediate layer 30, and a hard coat layer 40. The intermediate layer 30 is typically a compatible region containing components of the hard coat layer 40 and the protective layer 20. In an embodiment of the present invention, the thickness of the intermediate layer is 0.1 μm to 8 μm, and the shear fracture strength per μm of the intermediate layer thickness is 10 MPa or more. In an embodiment of the present invention, in a hard coat layer-attached polarizing plate having a non-rectangular irregular shape (irregularly processed portion), by forming the intermediate layer between the protective layer and the hard coat layer and setting the thickness and shear fracture strength per unit thickness of the intermediate layer within the above-mentioned ranges, chipping and cracking of the hard coat layer in the irregularly processed portion can be significantly suppressed. The shear fracture strength is the force required to cut (break) a single film or each layer of a laminate, and can be determined, for example, using SAICAS (Surface and Interfacial Cutting Analysis System). A specific procedure for determining the shear fracture strength will be described with reference to FIG. 2. FIG. 2 shows a laminate having, from top to bottom, a hard coat layer, an intermediate layer, and a protective layer. The shear fracture strength is the shear strength measured when the laminate is obliquely cut using a precision oblique cutting device (e.g., "SAICAS DN-20" manufactured by Daipla Wintes Co., Ltd.). Oblique cutting can be performed by biaxially moving the cutting blade (horizontally and vertically). The shear fracture strength T (MPa) can be determined using the following formula: T(MPa)=F H (kN) / (2×Wd(m 2 )×cotφ) where F Hwhere σ is the horizontal load applied by the cutting edge, W is the width of the cutting edge (m), d is the vertical displacement of the cutting edge (m), and φ is the shear angle. The shear angle can vary depending on the cutting conditions, the material of the workpiece, etc., but is generally 45°. Since the thickness of the intermediate layer and its shear strength are essentially proportional, the shear strength per 1 μm of intermediate layer thickness can be calculated. For example, if the shear strength of a 0.5 μm thick intermediate layer is measured, the measured value should be doubled; if the shear strength of a 2.0 μm thick intermediate layer is measured, the measured value should be halved.

[0011] In an embodiment of the present invention, the hard-coat-layer-attached polarizing plate has an irregular shape other than rectangular. In this specification, "having an irregular shape other than rectangular" refers to a shape other than rectangular (including rectangular shapes with chamfered corners) when viewed from above. The irregular shape is typically a deformed portion. Therefore, a "hard-coat-layer-attached polarizing plate having an irregular shape other than rectangular" (hereinafter sometimes referred to as an "irregular-shaped polarizing plate") encompasses not only an irregular-shaped polarizing plate whose entire shape (i.e., the outer edge defining the polarizing plate's shape when viewed from above) is other than rectangular, but also a rectangular polarizing plate with an irregular-shaped portion formed in a portion spaced inward from the outer edge. In a hard-coat-layer-attached polarizing plate, such irregular-shaped portions are prone to chipping and / or cracking in the hard-coat layer. However, according to an embodiment of the present invention, such chipping and cracking can be significantly suppressed. Examples of irregular shapes (irregular-shaped portions) include through-holes and machined portions that form recesses when viewed from above, as shown in FIGS. 3 and 4. Representative examples of recesses include a boat-like shape, a rectangle, an R-shaped bathtub shape, a V-shaped notch, and a U-shaped notch. Another example of an irregular shape (irregularly shaped portion) is a shape corresponding to an automobile meter panel, as shown in FIGS. 5 and 6. This shape includes a portion in which the outer edge is formed in an arc shape that follows the rotation direction of the meter needle and the outer edge forms a V-shape (including an R-shape) that is convex inward in the planar direction. Needless to say, the shape of the irregular shape (irregularly shaped portion) is not limited to the illustrated example. For example, the shape of the through hole may be any appropriate shape (e.g., ellipse, triangle, square, pentagon, hexagon, octagon) depending on the purpose, other than the approximately circular shape shown in the illustration. Furthermore, the through hole may be provided in any appropriate position depending on the purpose. The through-hole may be provided at approximately the center of the longitudinal end of the rectangular polarizing plate as shown in Fig. 4, at a predetermined position of the longitudinal end, or at a corner of the polarizing plate; or, although not shown, at the lateral end of the rectangular polarizing plate; or, as shown in Fig. 5 or 6, at the center of an irregularly shaped polarizing plate. As shown in Fig. 4, multiple through-holes may be provided. Furthermore, the shapes of the illustrated examples may be appropriately combined depending on the purpose.For example, through holes may be formed at any position in the irregular polarizing plate of FIG. 3; V-shaped notches and / or U-shaped notches may be formed at any appropriate position on the outer edge of the irregular polarizing plate of FIG. 5 or FIG. 6. Such irregular polarizing plates can be suitably used in image display devices such as automobile instrument panels, smartphones, tablet PCs, and smartwatches. When the irregular shape includes an R-shape, the radius of curvature is, for example, 0.2 mm or more, for example, 1 mm or more, or for example, 2 mm or more. On the other hand, the radius of curvature is, for example, 10 mm or less, or for example, 5 mm or less.

[0012] In the hard-coat-layer-attached polarizing plate, if necessary, another protective layer (not shown) may be provided on the side of the polarizer 10 opposite the protective layer 20. For convenience, the protective layer 20 may be referred to as an outer protective layer, and the other protective layer may be referred to as an inner protective layer. Furthermore, in the hard-coat-layer-attached polarizing plate, any appropriate functional layer may be provided on the side of the polarizer 10 opposite the protective layer 20 (or, if another protective layer is present, on the side of the other protective layer opposite the polarizer). Typical examples of the functional layer include a retardation layer and a conductive layer. The type, number, combination, etc. of the functional layer can be appropriately set depending on the purpose. For example, the optical properties (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the retardation layer can be appropriately set depending on the purpose.

[0013] In practice, a pressure-sensitive adhesive layer (not shown) is provided as the outermost layer on the side opposite the hard coat layer of the hard coat layer-attached polarizing plate, so that the hard coat layer-attached polarizing plate can be attached to an image display cell. Furthermore, it is preferable that a release film is temporarily attached to the surface of the pressure-sensitive adhesive layer until the hard coat layer-attached polarizing plate is used. Temporarily attaching the release film protects the pressure-sensitive adhesive layer and enables the hard coat layer-attached polarizing plate to be rolled.

[0014] The components of the hard coat layer-attached polarizing plate will be described in more detail below.

[0015] B. Polarizer A polarizer is typically made of a resin film containing a dichroic material. Any appropriate resin film that can be used as a polarizer can be adopted as the resin film. A typical resin film is a polyvinyl alcohol resin (hereinafter referred to as a "PVA resin") film. The resin film may be a single-layer resin film or a laminate of two or more layers.

[0016] Specific examples of polarizers composed of a single-layer resin film include PVA-based resin films that have been subjected to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio in the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the film may be dyed after stretching. If necessary, the PVA-based resin film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based resin film in water and washing it before dyeing, it is possible to clean off stains and antiblocking agents on the surface of the PVA-based film and also to swell the PVA-based resin film, thereby preventing uneven dyeing.

[0017] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching can optionally further include in-air stretching the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such polarizer manufacturing methods are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0018] The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0019] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0020] C. Protective layer Both the outer protective layer and the inner protective layer (sometimes collectively referred to as the protective layer) are formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that can be the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones. Other examples include glassy polymers such as siloxane polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0021] The outer protective layer is preferably made of a triacetyl cellulose (TAC) film or an acrylic resin film, more preferably a TAC film. By using such a film for the outer protective layer, an intermediate layer having the desired thickness and shear fracture strength can be successfully formed.

[0022] In one embodiment, the inner protective layer (if present) is preferably optically isotropic. In this specification, "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. In another embodiment, the inner protective layer may be a retardation film, a brightness enhancement film, a diffusion film, or the like.

[0023] The protective layer may have any appropriate thickness, and the thickness of the protective layer is preferably 5 μm to 200 μm, more preferably 15 μm to 45 μm, and even more preferably 20 μm to 40 μm.

[0024] D. Hard Coat Layer The hard coat layer preferably has a pencil hardness of H or more, more preferably 2H or more, and even more preferably 3H or more. On the other hand, the pencil hardness of the hard coat layer is preferably 6H or less, more preferably 5H or less. If the pencil hardness of the hard coat layer is in this range, excellent surface protection performance can be imparted when the polarizing plate with a hard coat layer is applied to an image display device. The pencil hardness can be measured based on the "Pencil Hardness Test" of JIS K 5400.

[0025] The thickness of the hard coat layer is preferably 5 μm or less, more preferably 0.5 μm to 4 μm, and even more preferably 1 μm to 3.5 μm. A hard coat layer thickness within this range can achieve excellent scratch resistance. Furthermore, by appropriately selecting the materials for the hard coat layer and the protective layer, an intermediate layer having the desired thickness and shear fracture strength can be successfully formed.

[0026] The hard coat layer may be made of any appropriate material as long as the effects of the present invention can be obtained. The hard coat layer may be, for example, a cured layer of a thermosetting resin or an ionizing radiation (e.g., visible light, ultraviolet) curable resin. An ultraviolet curable resin is preferred because it allows for easy operation and high efficiency in forming a hard coat layer. Specific examples of ultraviolet curable resins include polyester-based, (meth)acrylic-based, urethane-based, amide-based, silicone-based, epoxy-based, and unsaturated polyester-based ultraviolet curable resins. (Meth)acrylic ultraviolet curable resins include urethane (meth)acrylate, polyester (meth)acrylate, and epoxy (meth)acrylate. The ultraviolet curable resin may include ultraviolet curable monomers, oligomers, and polymers. A preferred ultraviolet curable resin is a resin composition containing an acrylic monomer or oligomer component having preferably two or more, more preferably three to six, ultraviolet polymerizable functional groups. Typically, a photopolymerization initiator is blended into the ultraviolet curable resin.

[0027] The hard coat layer can be formed by any appropriate method. The hard coat layer can be preferably formed by coating a resin composition for forming a hard coat layer on a protective layer, drying the coating, and curing the dried coating film by irradiating it with ultraviolet light. By directly coating the resin composition for forming a hard coat layer on the protective layer, an intermediate layer can be formed well.

[0028] Details of the hard coat layer are described in, for example, JP-A Nos. 2011-237789 and 2016-224443, the disclosures of which are incorporated herein by reference.

[0029] E. middle class As described above, the intermediate layer is typically a compatible region containing the components of the hard coat layer and the components of the protective layer. In other words, the intermediate layer is a permeation layer formed by the penetration of the hard coat components (substantially, the composition for forming a hard coat layer) into the protective layer. By forming the intermediate layer, the protective layer and the hard coat layer are firmly adhered to each other via the intermediate layer, thereby significantly suppressing chipping, cracking, and peeling of the hard coat layer. In the intermediate layer, the concentration of the protective layer components preferably increases continuously from the hard coat layer side to the protective layer side. The continuous change in the concentration of the protective layer components can prevent the formation of an interface within the intermediate layer due to changes in the concentration of the protective layer components. As a result, interfacial reflection within the intermediate layer can be suppressed, resulting in a polarizing plate with a hard coat layer that exhibits minimal interference unevenness. More preferably, the concentration of the protective layer components increases continuously from the hard coat layer to the intermediate layer, and also increases continuously from the intermediate layer to the protective layer. That is, more preferably, no clear interface is formed between the hard coat layer and the intermediate layer, and no clear interface is formed between the intermediate layer and the protective layer. With such a configuration, a polarizing plate with a hard coat layer having even less interference unevenness can be obtained.

[0030] As described above, the thickness of the intermediate layer is 0.1 μm to 8 μm, preferably 0.3 μm to 7.7 μm, more preferably 1.0 μm to 7.5 μm, and particularly preferably 1.2 μm to 7.5 μm. The thickness of the intermediate layer may be 5.0 μm or less, 2.0 μm or less, or 1.5 μm or less. If the thickness of the intermediate layer exceeds 8 μm, chipping and / or cracking of the hard coat layer in the irregularly shaped portion may not be sufficiently suppressed. If the thickness of the intermediate layer is less than 0.1 μm, peeling of the hard coat layer may occur in a high-temperature, high-humidity environment.

[0031] As described above, the shear fracture strength per 1 μm of thickness of the intermediate layer is 10 MPa or more, preferably 14 MPa or more. The shear fracture strength per 1 μm of thickness of the intermediate layer may be, for example, 16 MPa or more, or, for example, 20 MPa or more, or, for example, 25 MPa or more, or, for example, 40 MPa or more, or, for example, 70 MPa or more, or, for example, 100 MPa or more, or, for example, 120 MPa or more. The shear fracture strength per 1 μm of thickness of the intermediate layer may be, for example, 200 MPa or less. If the shear fracture strength per 1 μm of thickness of the intermediate layer is within this range, chipping and / or cracking of the hard coat layer in the irregularly shaped portion can be significantly suppressed.

[0032] The thickness and shear fracture strength of the intermediate layer can be adjusted by appropriately combining and setting the constituent material and surface properties of the substrate (which will ultimately become the protective layer) when forming the hard coat layer, the constituent material of the hard coat layer, the composition of the composition for forming the hard coat layer (e.g., solid content concentration, solvent composition, or type, number, or amount of additives), and the formation conditions of the hard coat layer (e.g., drying or heating conditions of the coating film, and ultraviolet irradiation amount or irradiation method).

[0033] F. Image display device As described above, the hard coat layer-attached polarizing plate according to the embodiment of the present invention can be suitably applied to an image display device. Accordingly, an image display device including a hard coat layer-attached polarizing plate is also encompassed in the embodiment of the present invention. The image display device typically includes an image display cell and a hard coat layer-attached polarizing plate bonded to the image display cell via an adhesive layer. The hard coat layer-attached polarizing plate is typically disposed on the viewing side of the image display cell, with the hard coat layer facing the viewing side. Examples of image display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, and quantum dot display devices. [Example]

[0034] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0035] (1) Thickness The thickness was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). (2) Shear fracture strength The laminate of the hard coat layer, intermediate layer (sometimes not formed in the comparative examples), and protective layer used in the examples and comparative examples was obliquely cut using a precision oblique cutting device (manufactured by Daipla Wintes, "SAICAS DN-20 type"), and the shear fracture strength was determined from the shear strength. The cutting conditions were as follows: Cutting edge: Single crystal diamond Blade width: 1mm Cutting edge rake angle: 10° Horizontal cutting edge speed: 1 μm / sec Vertical cutting edge speed: 0.05 μm / sec The shear fracture strength T (MPa) of the intermediate layer was determined using the following formula and converted into the amount per 1 μm of thickness. T(MPa)=F H (kN) / (2×Wd(m 2 )×cotφ) where F H is the horizontal load applied by the cutting edge, W is the width of the cutting edge (m), d is the vertical displacement of the cutting edge (m), and φ is 45°. (3) Chips or cracks in the hard coat layer The area around the through-holes in the polarizing plates with hard coat layers of the examples and comparative examples was photographed using an optical microscope (magnification: ×5). The photographed images were visually inspected for chipping and cracking in the hard coat layer (including the intermediate layer, if any) due to the formation of the through-holes, and evaluated according to the following criteria. Good: No chips or cracks were observed. Poor: Chips and / or cracks were observed. (4) Adhesion durability of hard coat layer The polarizing plates with hard coat layers of the Examples and Comparative Examples were left under high temperature and high humidity conditions (in an oven at 65°C and 90% RH) for 72 hours, and then the hard coat layer (including the intermediate layer, if any) was visually inspected for peeling and evaluated according to the following criteria. Good: No peeling was observed. Poor: Peeling was observed. (5) Scratch resistance The polarizing plates with hard coat layers of Examples and Comparative Examples were placed on a glass plate with the side without the hard coat layer facing down. Steel wool #0000 was evenly attached to the smooth cross section of a cylinder with a diameter of 11 mm, and the test sample surface was reciprocated 10 times at a speed of approximately 100 mm per second with a load of 1.0 kg. After that, the state of scratches on the hard coat layer surface was visually inspected and evaluated according to the following criteria. Good: No scratches were observed. Poor: Scratches were found.

[0036] Example 1 1. Preparation of Polarizing Plates A long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin made by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFFIMER") in a 9:1 ratio, to which 13 parts by weight of potassium iodide was added, in water. The above PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment). Next, the sample was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment). Thereafter, the film was dried in an oven maintained at about 90°C, and brought into contact with a heated roll made of SUS whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this manner, a polarizer having a thickness of about 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizer structure was obtained.

[0037] 2. Formation of hard coat layer and intermediate layer As film-forming components for the hard coat layer, 50 parts by weight of UV-curable acrylate resin (manufactured by Toagosei Co., Ltd., product name "M-920", 100% solids content) and 50 parts by weight of UV-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, product name "UV1700-TL", 80% solids content) were prepared. Per 100 parts by weight of the resin solids content of these resins, 3 parts by weight of photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907") and 0.15 parts by weight of leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "LE-303", 40% solids content) were mixed. This mixture was diluted with a mixed solvent of MIBK / cyclopentanone (70 / 30 by weight) to a solids concentration of 30%, to prepare a coating solution for forming the hard coat layer. A TAC film (manufactured by Fujifilm Corporation, product name "TJ25", thickness 25 μm) was prepared as a substrate (which would eventually become the protective layer). The above-mentioned hard coat layer-forming coating liquid was applied to one side of the substrate (side A, which is the side that comes into contact with the air when the TAC film is cast) using a bar coater to form a coating film. Next, the substrate on which the coating film was formed was heated at 80°C for 1 minute to dry the coating film. Thereafter, a high-pressure mercury lamp was used to apply the coating film to the substrate with an integrated light intensity of 300 mJ / cm. 2 The coating was cured by irradiating it with ultraviolet light. In this way, a laminate of substrate / cured coating was obtained. The total thickness of the cured coating was 2.6 μm, of which the thickness of the hard coat layer was 1.3 μm and the thickness of the intermediate layer was 1.3 μm. The shear fracture strength per μm of thickness of the intermediate layer was 125 MPa.

[0038] 3. Preparation of polarizing plate with hard coat layer The substrate / cured coating film laminate obtained in 2. above was bonded to the polarizer surface of the resin substrate / polarizer laminate (polarizing plate) obtained in 1. above via an acrylic adhesive, with the substrate adjacent to the polarizer. The resin substrate was then peeled off, and a conventional TAC film serving as a backing for profile processing was bonded to the peeled surface via an active energy ray-curable adhesive (0.7 μm thick). The active energy ray-curable adhesive was applied using an MCD coater (manufactured by Fuji Machine Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 1000 rolls / inch, rotation speed: 140% / line speed). The active energy ray-curable adhesive was then cured by irradiating both sides with visible light using an active energy ray irradiation device, followed by hot air drying at 70°C for 3 minutes to obtain a hard coat layer-attached polarizing plate having a hard coat layer / intermediate layer / protective layer / polarizer / backing structure. The active energy ray-curable adhesive was prepared as follows. A mixture of 12 parts by weight of a radical polymerizable compound (a), 35 parts by weight of a radical polymerizable compound (b), 40 parts by weight of a radical polymerizable compound (c), 10 parts by weight of an oligomer compound (d), 2 parts by weight of a photopolymerization initiator (e), and 1 part by weight of a photosensitizer (f) was stirred at 50°C for 1 hour to obtain an active energy ray-curable adhesive. The radical polymerizable compound (a) was HEAA (hydroxyethyl acrylamide) (manufactured by KJ Chemicals); the radical polymerizable compound (b) was ACMO (acroylmorpholine) (manufactured by KJ Chemicals); the radical polymerizable compound (c) was Light Acrylate 1,9ND-A (1,9-nonanediol diacrylate) (manufactured by Kyoeisha Chemical Co., Ltd.); the oligomeric compound (d) was ARUFON UG-4010 (epoxy group-modified acrylic oligomer) (manufactured by Toagosei Co., Ltd.); the photopolymerization initiator (e) was Omnirad907 (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one) (manufactured by IGM Resins BV); and the photosensitizer (f) was KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.).

[0039] 4. Processing polarizing plates with hard coat layers into irregular shapes The hard-coated polarizing plate obtained in 3 above was punched out into a shape measuring 142.0 mm in length and 66.8 mm in width, with rounded corners of 7.0 mm radius. The punching was performed so that the absorption axis direction of the polarizer was aligned with the short side. Furthermore, through-holes with a diameter of 4.0 mm were formed 2 mm from the long side and 2 mm from the short side by end milling. The through-holes were formed by end milling. The end mill feed rate was 750 mm / min, the rotation speed was 10,000 rpm, and the removal amount was 0.1 mm / cycle. In this way, a hard-coated polarizing plate having through-holes was obtained. The obtained hard-coated polarizing plate was subjected to the evaluations (3) to (5) above. The results are shown in Table 1.

[0040] <Example 2> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 1, except that a cured coating film having a total thickness of 7.4 μm was formed using the following coating liquid for forming a hard coat layer. The hard coat layer had a thickness of 3.0 μm, and the intermediate layer had a thickness of 4.4 μm. The shear fracture strength per μm of intermediate layer thickness was 14 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1. As a film-forming component for the hard coat layer, 100 parts by weight of UV-curable acrylate resin (manufactured by DIC Corporation, product name "Luxidia 17-806", solid content 80%) was prepared. Per 100 parts by weight of resin solid content, 3 parts by weight of photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907") and 0.01 part by weight of leveling agent (manufactured by DIC Corporation, product name "GRANDIC PC4100", solid content 10%) were mixed. This mixture was diluted with a PGME / cyclopentanone mixed solvent (weight ratio 65 / 35) to a solid content concentration of 36%, to prepare a coating solution for forming the hard coat layer.

[0041] Example 3 A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 1, except that a 40 μm-thick TAC film (manufactured by Fujifilm Corporation, product name "TJ40") was used as the substrate (protective layer), the following coating liquid for forming a hard coat layer was used, the coating film before curing was heated at 60°C for 1 minute, and a cured coating film with a total thickness of 10.1 μm was formed. The hard coat layer had a thickness of 3.3 μm, and the intermediate layer had a thickness of 6.8 μm. The shear fracture strength per μm of intermediate layer thickness was 18 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1. As a film-forming component for the hard coat layer, 100 parts by weight of an ultraviolet-curable acrylate resin (manufactured by DIC Corporation, trade name "Luxidia 17-806", solids content 80%) was prepared. Per 100 parts by weight of the resin solids, 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907") and 0.01 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "GRANDIC PC4100", solids content 10%) were mixed. This mixture was diluted with a PGME / cyclopentanone mixed solvent (weight ratio 50 / 50) to a solids concentration of 36%, to prepare a coating solution for forming a hard coat layer.

[0042] Example 4 A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 1, except that a 25 μm-thick TAC film (manufactured by Fujifilm Corporation, product name "TJ25UL") was used as the substrate (protective layer), and a cured coating film with a total thickness of 9.3 μm was formed using the following coating liquid for forming an antiglare layer (anti-glare layer). The antiglare layer had a thickness of 1.8 μm, and the intermediate layer had a thickness of 7.5 μm. The shear fracture strength per μm of intermediate layer thickness was 27 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1. As film-forming components for the antiglare layer, 50 parts by weight of an ultraviolet-curable urethane acrylate resin (manufactured by Mitsubishi Chemical Corporation under the trade name "UV1700B") and 50 parts by weight of a polyfunctional acrylate whose main component is pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd. under the trade name "Viscoat #300") were prepared. Per 100 parts by weight of the total solids content of these resins, 2 parts by weight of acrylic and styrene copolymer particles (manufactured by Sekisui Plastics Co., Ltd. under the trade name "Techpolymer SSX1055QXE") were used as antiglare layer-forming particles, 1.5 parts by weight of synthetic smectite (manufactured by Kunimine Industries Co., Ltd. under the trade name "Sumecton SAN") was used as a thixotropy-imparting agent, 3 parts by weight of a photopolymerization initiator (manufactured by BASF under the trade name "OMNIRAD907"), and 0.15 parts by weight of a leveling agent (manufactured by DIC Corporation under the trade name "GRANDIC PC4100", 10% solids content) were mixed. This mixture was diluted with a toluene / cyclopentanone mixed solvent (weight ratio 80 / 20) so that the solid content concentration was 50%, to prepare a coating liquid for forming an antiglare layer.

[0043] <Example 5> A polarizing plate was fabricated in the same manner as in Example 1. Meanwhile, a hard coat layer and an intermediate layer were formed as follows. As the resins contained in the hard coat layer, 50 parts by weight of an ultraviolet-curable acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DCP", 100% solids content) and 50 parts by weight of an ultraviolet-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, product name "UV1700-TL", 80% solids content) were prepared. Five parts by weight of a photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907") and 0.2 parts by weight of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "LE-303", 40% solids content) were mixed per 100 parts by weight of the resin solids content. This mixture was diluted with a mixed solvent of MIBK and cyclopentanone (weight ratio 60 / 40) to a solids concentration of 30%, to prepare a coating liquid for forming a hard coat layer. A TAC film (manufactured by Fujifilm Corporation, product name "TJ25UL") was prepared as a substrate (which would eventually become the protective layer). The hard coat layer-forming coating liquid was applied to one side of the substrate (side A, which is the side that comes into contact with the air during casting of the TAC film) using a bar coater to form a coating film. The substrate on which the coating film was formed was then heated at 60°C for 1 minute to dry the coating film. Thereafter, a high-pressure mercury lamp was used to apply the coating film to the substrate with an integrated light intensity of 220 mJ / cm. 2 The coating film was cured by irradiating it with ultraviolet light. In this way, a laminate of substrate / cured coating film was obtained. The thickness of the hard coat layer was 2.8 μm, and the thickness of the intermediate layer was 0.4 μm. The shear fracture strength per μm of thickness of the intermediate layer was 148 MPa. A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 1. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0044] Example 6 A polarizing plate was fabricated in the same manner as in Example 1. Meanwhile, a hard coat layer and an intermediate layer were formed as follows. 50 parts by weight of an ultraviolet-curable acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DCP," solid content 100%) and 50 parts by weight of an ultraviolet-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, product name "UV1700-TL," solid content 80%) were prepared as the resins contained in the hard coat layer. 5 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907") and 0.1 parts by weight of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "LE-303," solid content 40%) were mixed per 100 parts by weight of the resin solid content. This mixture was diluted with a mixed solvent of MIBK and cyclopentanone (weight ratio 60 / 40) to a solid content concentration of 30%, to prepare a coating liquid for forming a hard coat layer. A TAC film (manufactured by Fujifilm Corporation, product name "TJ25UL") was prepared as a substrate (which would eventually become the protective layer). The hard coat layer-forming coating liquid was applied to one side of the substrate (side A, which is the side that comes into contact with the air during TAC film casting) using a bar coater to form a coating film. The substrate on which the coating film was formed was then heated at 60°C for 1 minute to dry the coating film. Thereafter, a high-pressure mercury lamp was used to apply the coating film to the substrate with an integrated light intensity of 260 mJ / cm. 2 The coating was cured by irradiating ultraviolet light of 1000 kJ / cm². In this way, a laminate of substrate / cured coating was obtained. The thickness of the hard coat layer was 2.5 μm, and the thickness of the intermediate layer was 0.7 μm. The shear fracture strength per μm of thickness of the intermediate layer was 86 MPa. A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 1. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0045] <Comparative Example 1> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 2, except that the total thickness of the cured coating film was 6.6 μm, a 25 μm-thick TAC film (manufactured by Konica Minolta, Inc., product name "KC2UA") was used as the substrate (protective layer), and a hard coat layer was formed on side B of the TAC film (the side that comes into contact with the support surface during TAC film casting). The hard coat layer had a thickness of 2.7 μm, and the intermediate layer had a thickness of 3.9 μm. The shear fracture strength of the intermediate layer was 9 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0046] <Comparative Example 2> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Comparative Example 1, except that a cured coating film having a total thickness of 8.7 μm was formed using the following hard coat layer-forming coating liquid. The hard coat layer had a thickness of 3.3 μm, and the intermediate layer had a thickness of 5.4 μm. The shear fracture strength of the intermediate layer was 9 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1. As a film-forming component for the hard coat layer, 100 parts by weight of an ultraviolet-curable acrylate resin (manufactured by DIC Corporation, trade name "Luxidia 17-806," solids content 80%) was prepared. Per 100 parts by weight of the resin solids, 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907") and 0.01 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "GRANDIC PC4100," solids content 10%) were mixed. This mixture was diluted with a PGME / cyclopentanone / butyl acetate mixed solvent (weight ratio 9 / 40 / 51) to a solids concentration of 36%, to prepare a coating solution for forming the hard coat layer.

[0047] <Comparative Example 3> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 2, except that the total thickness of the cured coating film was 1.6 μm and a 20 μm-thick polycarbonate (PC) resin film (manufactured by Mitsubishi Chemical Corporation, product name "DURABIO" extrusion-molded film) was used as the substrate (protective layer). The thickness of the hard coat layer was 1.6 μm, and no intermediate layer was formed. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0048] <Comparative Example 4> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 2, except that the total thickness of the cured coating film was 1.4 μm and a 26 μm-thick cyclic olefin resin (COP) film (manufactured by Zeon Corporation, product name "ZF12") was used as the substrate (protective layer). The thickness of the hard coat layer was 1.4 μm, and no intermediate layer was formed. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0049] <Comparative Example 5> A polarizing plate with a hard coat layer having through holes was obtained in the same manner as in Example 2, except that the total thickness of the cured coating film was 10.4 μm and a 40 μm-thick acrylic resin film (manufactured by Nitto Denko Corporation, product name "HX-40UF") was used as the substrate (protective layer). The hard coat layer had a thickness of 1.2 μm, and the intermediate layer had a thickness of 9.2 μm. The shear fracture strength of the intermediate layer was 17 MPa. The obtained polarizing plate with a hard coat layer was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0050] <Reference example> The hard-coat-layer-attached polarizing plates prepared according to the configurations described in Examples 1 to 4 and Comparative Examples 1 to 5 were punched out to a size of 142.0 mm in length and 66.8 mm in width. The punching was performed so that the absorption axis direction of the polarizer was aligned with the short side direction. The four sides were cut off in 0.5 mm increments using a processing blade angled at 10 degrees to process the edges. The feed rate of the processing machine was 600 mm / min, and the rotation speed was 6000 rpm. In this way, rectangular hard-coat-layer-attached polarizing plates (i.e., without irregular shapes) with processed edges were obtained. The obtained hard-coat-layer-attached polarizing plates were each subjected to the evaluation (3) above, and good results were obtained for all of the hard-coat-layer-attached polarizing plates.

[0051] [Table 1]

[0052] <Evaluation> As is clear from Table 1, according to the examples of the present invention, in a polarizing plate with a hard coat layer having a contoured portion, by forming an intermediate layer between the protective layer and the hard coat layer and setting the thickness and shear fracture strength per unit thickness of the intermediate layer to a predetermined value or more, chipping and cracking of the hard coat layer in the contoured portion can be significantly suppressed. Furthermore, it can be seen that the polarizing plate with a hard coat layer of the examples of the present invention also has excellent adhesion durability and scratch resistance of the hard coat layer. [Industrial Applicability]

[0053] The polarizing plate with a hard coat layer of the present invention can be suitably used in image display devices, and in particular, can be suitably used in image display devices having irregularly shaped parts, such as instrument panels for automobiles, smartphones, tablet PCs, or smartwatches. [Explanation of symbols]

[0054] 10 Polarizer 20 protective layer 30 Middle Class 40 Hard coat layer 100 Polarizing plate with hard coat layer

Claims

[Claim 1] The polarizer includes a protective layer, an intermediate layer having a thickness of 0.1 μm to 8 μm, and a hard coat layer, in this order; It has an irregular shape other than a rectangle, The shear fracture strength per 1 μm of thickness of the intermediate layer is 10 MPa or more. Polarizing plate with hard coat layer.

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