Optical multilayer plates, image display panels, and image display devices.

Abstract

The invention relates to an optical multilayer consisting of a pressure-sensitive adhesive layer, an antistatic layer, and an optical film. The antistatic layer satisfies the following inequality (1). The symbols A and B in inequality (1) are respectively the surface resistivity (units: Ω / □) of the antistatic layer measured before and after weather resistance testing (test condition: Z-IN1) as specified in the German industrial standard DIN 75220. The aforementioned optical multilayer is suitable for application in photo display devices used in harsh environments, such as automotive environments. −2 ≤ logB − logA ≤ 2 (1)

Description

Optical laminate, image display panel and image display device

[0001] The present invention relates to an optical laminate, an image display panel, and an image display device.

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), are becoming widespread. These image display devices have a laminated structure of, for example, an image display cell, such as a liquid crystal cell or an EL light-emitting element, and an optical laminate including a polarizing film and a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet is mainly used to bond between films included in the optical laminate or to bond the image display cell and the optical laminate.

[0003] Static electricity may be generated during the manufacture or use of an image display device. During manufacture, static electricity is likely to be generated when an optical laminate is attached to an image display cell via an adhesive sheet. During use, static electricity is likely to be generated when a user touches the image display device. If the image display device becomes charged by static electricity, display defects may occur. Patent Document 1 discloses an optical laminate including a polarizing film and a conductive layer containing a conductive polymer.

[0004] Special Publication No. 2015-509615

[0005] According to the studies of the present inventors, there is room for further improvement in the optical laminate of Patent Document 1 depending on the environment in which the image display device is used. An object of the present invention is to provide an optical laminate suitable for application to an image display device used in a harsh environment, such as an in-vehicle image display device.

[0006] The present invention provides an optical laminate including a pressure-sensitive adhesive sheet, an antistatic layer, and an optical film, wherein the antistatic layer satisfies the following formula (1): -2≦log B−log A≦2 (1) where A and B in formula (1) respectively represent the surface resistivities (unit: Ω / □) of the antistatic layer before and after a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220.

[0007] The present invention further provides an optical laminate comprising, in this order, a pressure-sensitive adhesive sheet, an antistatic layer, and an optical film, which satisfies the following formula (4): -1≦log D−log C≦2 (4) where C in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate, and D in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate after the optical laminate has undergone a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220.

[0008] The present invention further provides an image display panel comprising the above optical laminate.

[0009] The present invention further provides an image display device comprising the above image display panel.

[0010] According to the present invention, an optical laminate suitable for application to an image display device used in a harsh environment such as an in-vehicle display can be provided.

[0011] FIG. 1 is a cross-sectional view schematically showing an example of an optical laminate according to the present embodiment. FIG. 2 is a schematic view illustrating a method for testing the curl diameter of a polarizing film. FIG. 3 is a schematic view illustrating the bending moment M of a polarizing film when heated. FIG. 4 is a cross-sectional view schematically showing another example of an optical laminate according to the present embodiment. FIG. 5 is a cross-sectional view schematically showing an example of an image display panel according to the present embodiment. FIG. 6 is a cross-sectional view schematically showing another example of an image display panel according to the present embodiment. FIG. 7 is a cross-sectional view schematically showing another example of an image display panel according to the present embodiment.

[0012] An optical laminate according to a first aspect of the present invention is an optical laminate including a pressure-sensitive adhesive sheet, an antistatic layer, and an optical film, wherein the antistatic layer satisfies the following formula (1), where A and B in formula (1) are the surface resistivities (unit: Ω / □) of the antistatic layer before and after a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220, respectively. -2≦log B−log A≦2 (1)

[0013] In the second aspect of the present invention, for example, in the optical laminate according to the first aspect, the surface resistivity B of the antistatic layer is 1.0 × 10 6 Ω / □ or more 3.0×10 8 Ω / □ or less.

[0014] In a third aspect of the present invention, for example, in the optical laminate according to the first or second aspect, the antistatic layer has a thickness of 5 nm or more and 100 nm or less.

[0015] In a fourth aspect of the present invention, for example, in the optical laminate according to any one of the first to third aspects, the antistatic layer contains carbon nanotubes.

[0016] In a fifth aspect of the present invention, for example, in the optical laminate according to the fourth aspect, the carbon nanotubes have a length of 3 μm or more and 300 μm or less, and a diameter of 10 nm or less.

[0017] In a sixth aspect of the present invention, for example, in the optical laminate according to any one of the first to fifth aspects, the antistatic layer contains a binder resin.

[0018] In a seventh aspect of the present invention, for example, in the optical laminate according to any one of the first to sixth aspects, the antistatic layer contains a binder resin having a glass transition temperature of 0° C. or higher.

[0019] In an eighth aspect of the present invention, for example, in the optical laminate according to any one of the first to seventh aspects, the antistatic layer is substantially free of a leveling agent.

[0020] In a ninth aspect of the present invention, for example, in the optical laminate according to any one of the first to eighth aspects, the pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive composition containing a polymer (A).

[0021] In a tenth aspect of the present invention, for example, in the optical laminate according to the ninth aspect, the polymer (A) is a (meth)acrylic polymer.

[0022] In an eleventh aspect of the present invention, for example, in the optical laminate according to the ninth or tenth aspect, the pressure-sensitive adhesive composition contains the polymer (A) having a polyether structure as a main component.

[0023] In a twelfth aspect of the present invention, for example, in the optical laminate according to the eleventh aspect, the polymer (A) has a constituent unit derived from a monomer represented by the following formula (2). R in formula (2) 1 is a hydrogen atom or a methyl group, and R 2 is an alkyl group which may be linear or branched, and n is an integer of 1 to 15.

[0024] In a thirteenth aspect of the present invention, for example, in the optical laminate according to any one of the ninth to twelfth aspects, the pressure-sensitive adhesive composition further contains an antistatic agent.

[0025] In a fourteenth aspect of the present invention, for example, in the optical laminate related to the thirteenth aspect, in the pressure-sensitive adhesive composition, the blending amount of the antistatic agent relative to 100 parts by weight of the polymer (A) is less than 30 parts by weight.

[0026] In a fifteenth aspect of the present invention, for example, in the optical laminate according to any one of the first to fourteenth aspects, the loss in the total light transmittance due to the antistatic layer is 1.0% or less.

[0027] In a sixteenth aspect of the present invention, for example, in the optical laminate according to any one of the first to fifteenth aspects, the optical film includes a polarizing film.

[0028] In a seventeenth aspect of the present invention, for example, in the optical laminate according to the sixteenth aspect, the curl diameter of the polarizing film evaluated by the following test method is 3 mm or more. <Test Method> A test piece is prepared by processing the polarizing film into a rectangle having a width of 10 mm and a length of 50 mm, with the absorption axis of the polarizer aligned in the longitudinal direction. Next, one longitudinal end of the test piece is fixed to the surface of an evaluation sheet. Next, the entire test piece is heated at 105°C for 12 hours, and the test piece is curled from the other longitudinal end of the test piece. The diameter of the cylindrical portion of the test piece formed by curling is determined as the curl diameter.

[0029] In an eighteenth aspect of the present invention, for example, in the optical laminate according to the sixteenth or seventeenth aspect, the absolute value of the bending moment M of the polarizing film when heated is 1 × 10 9 is less than.

[0030] In a nineteenth aspect of the present invention, for example, in the optical laminate according to any one of the first to eighteenth aspects, the antistatic layer contains carbon nanotubes and a binder resin having a glass transition temperature of 0°C or higher.

[0031] In a twentieth aspect of the present invention, for example, in the optical laminate according to the nineteenth aspect, the carbon nanotubes have a length of 3 μm or more and 300 μm or less, and a diameter of 10 nm or less.

[0032] In a 21st aspect of the present invention, for example, the optical laminate according to any one of the first to 20th aspects includes the pressure-sensitive adhesive sheet, the antistatic layer, and the optical film in this order, and satisfies the following formula (4): -1≦log D−log C≦2 (4) where C in the formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate, and D in the formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate that has undergone the weather resistance test.

[0033] An optical laminate according to a 22nd aspect of the present invention comprises a pressure-sensitive adhesive sheet, an antistatic layer, and an optical film, in this order, and satisfies the following formula (4): -1≦log D−log C≦2 (4) where C in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate, and D in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate that has undergone a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220.

[0034] An image display panel according to a twenty-third aspect of the present invention includes the optical laminate according to any one of the first to twenty-second aspects.

[0035] An image display device according to a twenty-fourth aspect of the present invention includes the image display panel according to the twenty-third aspect.

[0036] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments. The present invention can be implemented in any modified form without departing from the gist of the present invention.

[0037] [Optical Laminate] An example of the optical laminate of this embodiment is shown in Figure 1. The optical laminate 10 (10A) in Figure 1 includes an adhesive sheet 1, an antistatic layer 2, and an optical film 3. The optical laminate 10A has a structure in which the adhesive sheet 1, the antistatic layer 2, and the optical film 3 are laminated in this order. However, the order in which the layers in the optical laminate are laminated is not limited to the example in Figure 1. The optical laminate 10A can be attached to an object such as an image display panel via the adhesive sheet 1.

[0038] The pressure-sensitive adhesive sheet 1 in Fig. 1 is in contact with the antistatic layer 2. However, other films and / or layers may be disposed between the pressure-sensitive adhesive sheet 1 and the antistatic layer 2. The pressure-sensitive adhesive sheet 1 in Fig. 1 is formed on the entirety of one main surface of the antistatic layer 2 when viewed in the stacking direction. However, the pressure-sensitive adhesive sheet 1 may be formed on only a part of one main surface of the antistatic layer 2 when viewed in the stacking direction. In this specification, the "main surface" means the surface of the film or layer having the largest area.

[0039] The optical film 3 in Fig. 1 is in contact with the antistatic layer 2. However, other films and / or layers may be disposed between the optical film 3 and the antistatic layer 2. The optical film 3 in Fig. 1 is formed over the entire other main surface of the antistatic layer 2 when viewed in the stacking direction. However, the optical film 3 may be formed over only a part of the other main surface of the antistatic layer 2 when viewed in the stacking direction.

[0040] The antistatic layer 2 in FIG. 1 is sandwiched between an adhesive sheet 1 and an optical film 3 .

[0041] <Antistatic Layer> The antistatic layer 2 satisfies the following formula (1), where A and B in formula (1) are the surface resistivities (unit: Ω / □) of the antistatic layer 2 before and after a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220. −2≦log B−log A≦2 (1)

[0042] According to the inventors' investigations, resistance changes in the antistatic layer 2 due to exposure to harsh environments such as in-vehicle applications can be a cause of display defects. Furthermore, in an image display device incorporating a touch sensor, resistance changes in the antistatic layer 2 can be a cause of malfunction of the touch sensor. The weather resistance test specified in DIN 75220 (hereinafter referred to as the "DIN test") is a weather resistance test that takes into account the above-mentioned harsh environments. The change in surface resistivity of the antistatic layer 2 before and after the DIN test is suppressed. Therefore, the optical laminate 10 including the antistatic layer 2 is more suitable for suppressing display defects. Note that the test condition Z-IN1 in the DIN test refers to a cycle test (Z) for indoor (Zone 1) environments, consisting of a 15-day dry climate cycle followed by a 10-day wet climate cycle. The dry climate cycle consisted of (1) 8 hours of UV irradiation in an atmosphere at a temperature of 80°C and a relative humidity of 20%, (2) 3.5 hours of exposure in an atmosphere at a temperature of 10°C and a relative humidity of 60% (without UV irradiation), (3) 8 hours of UV irradiation in an atmosphere at a temperature of 80°C and a relative humidity of 20%, and (4) 3.5 hours of exposure in an atmosphere at a temperature of 10°C and a relative humidity of 60% (without UV irradiation), and this cycle was repeated for 15 days. However, between (4) of one cycle and (1) of the next cycle, a 1-hour exposure at room temperature (23°C) was performed. The humid climate cycle consisted of (1) 5 hours of exposure in an atmosphere at a temperature of -10°C (without UV irradiation), (2) 12 hours of UV irradiation in an atmosphere at a temperature of 80°C and a relative humidity of 50%, and (3) 6 hours of exposure in an atmosphere at a temperature of -10°C (without UV irradiation), and this cycle was repeated for 10 days. However, between (3) of one cycle and (1) of the next cycle, the test specimens are left at room temperature for one hour. Indoor (Zone 1) refers to the location of on-board components and materials in a vehicle, and refers to interior components and materials that are exposed to high temperatures but have a lower sunlight irradiation intensity than the exterior. The illuminance of the metal halide lamp used for ultraviolet irradiation is 830 W / m 2 Let's say.

[0043] Log B - log A in formula (1) may be -1.7 or more and 1.7 or less, -1.5 or more and 1.5 or less, -1.3 or more and 1.3 or less, -1.2 or more and 1.2 or less, -1.1 or more and 1.1 or less, -1 or more and 1 or less, -0.9 or more and 0.9 or less, -0.8 or more and 0.8 or less, -0.7 or more and 0.7 or less, -0.6 or more and 0.6 or less, or even -0.5 or more and 0.5 or less.

[0044] Log B - log A in formula (1) can vary depending on the composition and formation method of the antistatic layer 2. Examples of the composition are the type and content of the conductive material, and the type, content and properties of materials contained other than the conductive material. Examples of materials contained other than the conductive material are binder resins and leveling agents. Examples of the formation method are the composition and formation conditions of the coating liquid for forming the antistatic layer 2. An example of the composition of the coating liquid is the type of solvent. An example of the formation conditions is the drying temperature of the coating liquid.

[0045] The surface resistivity B of the antistatic layer 2 (surface resistivity after DIN test) is, for example, 1.0×10 9 Ω / □ or less. 3.0×10 8 The antistatic layer 2 having a surface resistivity B of 5.0×10 Ω / □ or less is particularly suitable for suppressing display defects in image display devices. 8 Ω / □ or less, 2.0×10 8 Ω / □ or less, 1.0×10 8 Ω / □ or less, 9.0×10 7 Ω / □ or less, 8.0×10 7 Ω / □ or less, 7.0×10 7 Ω / □ or less, 6.0×10 7 Ω / □ or less, 5.0×10 7 Ω / □ or less, 4.0×10 7 Ω / □ or less, and even 3.0×10 7 The lower limit of the surface resistivity B may be, for example, 1.0 × 10 6 Ω / □ or more, and 2.0×10 6 Ω / □ or more, 3.0×10 6 Ω / □ or more, 4.0×10 6 Ω / □ or more, 5.0×10 6 Ω / □ or more, 6.0×10 6 Ω / □ or more, 7.0×106 Ω / □ or more, 8.0×10 6 Ω / □ or more, 9.0×10 6 Ω / □ or more, and even 1.0×10 7 It may be 2.0×10 Ω / □ or more. 6 Ω / □ or more, 5.0×10 6 Ω / □ or more, and even 1.0×10 7 The antistatic layer 2 having a surface resistivity B of Ω / □ or more can contribute to ensuring touch sensitivity in an image display device equipped with a touch sensor or touch panel, particularly in an in-cell type image display device described later. 6 Ω / □ or more 3.0×10 8 Ω / □ or less, and may be 1.0×10 6 Ω / □ or more 1.0×10 8 Ω / □ or less, 1.0×10 6 Ω / □ or more 1.0×10 7 Ω / □ or less, and even 5.0×10 6 Ω / □ or more 1.0×10 7 It may be Ω / □ or less.

[0046] The surface resistivity A (surface resistivity before the DIN test) of the antistatic layer 2 can have an example range that is the same as the example range that the surface resistivity B can have. The surface resistivity A of the antistatic layer 2 can have an example range that is 1.0×10 6 Ω / □ or more 3.0×10 8 Ω / □ or less, and may be 1.0×10 7 Ω / □ or more 1.0×10 8 Ω / □ or less, and even 1.0×10 7 Ω / □ or more 5.0×10 7 It may be Ω / □ or less.

[0047] The antistatic layer 2 may be a layer whose surface resistivity is maintained or decreased by the DIN test. In other words, the relationship between the surface resistivity A and the surface resistivity B may be expressed by the formula: surface resistivity B≦surface resistivity A, or the relationship between the surface resistivity B<surface resistivity A.

[0048] The surface resistivities A and B of the antistatic layer 2 can be determined by the following method. A laminate is prepared in which the surface of the antistatic layer 2 is exposed to the outside. An example of such a laminate is a laminate including an optical film 3 and an antistatic layer 2. Next, the surface resistivity of the exposed surface of the antistatic layer 2 in the prepared laminate is measured. The surface resistivity can be measured using a high-resistance resistivity meter (for example, the Hiresta series manufactured by Mitsubishi Chemical Analytech Co., Ltd.) in accordance with the method defined in Japanese Industrial Standards (JIS) K6911:1995. However, the surface resistivities A and B are measured at an applied voltage of 10 V, an application time of 10 seconds, and an ambient temperature of 25±3°C.

[0049] The antistatic layer 2 typically contains a conductive material. Examples of conductive materials include conductive polymers, composites of conductive polymers and dopants, conductive fine particles, carbon materials, ionic surfactants, and ionic compounds. Examples of carbon materials include acetylene black, ketjen black, natural graphite, artificial graphite, and carbon nanotubes (CNTs). According to the inventors' studies, carbon materials are suitable as the conductive material contained in the antistatic layer 2, with CNTs being particularly suitable. In other words, the antistatic layer 2 may contain either a carbon material or CNTs. A carbon material is suitable because it is less susceptible to deterioration, typically oxidation, in the above-mentioned harsh environments than conductive polymers or composites of conductive polymers and dopants. Deterioration of the conductive material typically increases the surface resistivity of the antistatic layer 2. Furthermore, the particular suitability of CNTs among carbon materials may be due to the fact that their high shape anisotropy suppresses aggregation and orientation under high temperatures and high humidity. The antistatic layer 2 may contain two or more types of conductive materials, and may contain CNTs and another conductive material (for example, a conductive polymer).

[0050] The type of CNT is not limited, and CNTs produced by various methods such as arc discharge, laser evaporation, and chemical vapor deposition (CVD) can be used. The CNTs may be single-walled CNTs, double-walled CNTs, or multi-walled CNTs, or may be a mixture of two or more of these. From the viewpoint of excellent conductivity, single-walled CNTs are particularly suitable.

[0051] The length of the CNT may be, for example, 1 to 2000 μm, 1 to 1000 μm, or even 1 to 500 μm. The diameter (outer diameter) of the CNT may be, for example, 0.1 to 50 nm, 0.2 to 40 nm, 0.25 to 30 nm, 0.3 to 20 nm, 0.4 to 15 nm, or even 0.5 to 10 nm. The diameter of the CNT may be 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4.5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, or even 2 nm or less. From the viewpoint of dispersibility in the antistatic layer 2, the length of the CNTs may be 300 μm or less, or may be less than 300 μm, 275 μm or less, 250 μm or less, 225 μm or less, 200 μm or less, 175 μm or less, 150 μm or less, 125 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, less than 10 μm, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or even 5 μm or less. From the viewpoint of dispersibility in the antistatic layer 2, the length of the CNTs may be 3 μm or more and 300 μm or less, and the diameter may be 10 nm or less. The length of the CNTs can be evaluated by observation using an atomic force microscope (AFM) or a scanning electron microscope (SEM), and the diameter of the CNTs can be determined in accordance with the specifications of ISO / TS 10868:2017.

[0052] The content of CNT in the antistatic layer 2 is, for example, 0.01 to 50.0 mg / m 2 and 0.1 to 10.0 mg / m 2 The proportion of CNTs in the total solid content contained in the antistatic layer 2 may be, for example, 0.01 to 90 wt %, 0.01 to 50 wt %, 0.01 to 30 wt %, 0.05 to 25 wt %, 0.1 to 20 wt %, 0.15 to 15 wt %, 0.2 to 10 wt %, 0.25 to 7.5 wt %, 0.5 to 5 wt %, or even 0.75 to 3 wt %. From the viewpoint of suppressing loss in total light transmittance of the optical laminate 10, a smaller proportion is preferable.

[0053] Known materials can be used for the conductive polymer, the composite of the conductive polymer and the dopant, the conductive fine particles, the ionic surfactant, and the ionic compound.

[0054] The antistatic layer 2 may contain one or more conductive materials.

[0055] The antistatic layer 2 may contain a material other than the conductive material. An example of such a material is a binder resin. In other words, the antistatic layer 2 may contain a binder resin. The inclusion of a binder resin can contribute to improving the film-forming properties of the antistatic layer 2 and improving the adhesion and bonding (anchoring force) of the antistatic layer 2 to the optical film 3.

[0056] Examples of binder resins include oxazoline group-containing polymers, polyurethane resins, polyester resins, acrylic resins, polyether resins, cellulose resins, polyvinyl alcohol resins, epoxy resins, polyvinylpyrrolidone, polystyrene resins, polyethylene glycol, and pentaerythritol. The binder resin is preferably an oxazoline group-containing polymer, polyurethane resin, polyester resin, or acrylic resin, and particularly preferably a polyurethane resin and / or an acrylic resin. The antistatic layer 2 may contain one or more binder resins, or may contain only one. A combination of two or more binder resins may be a combination of a polyurethane resin and an acrylic resin. The binder content in the antistatic layer 2 may be, for example, 1 to 99.99 wt %, 50 to 99.99 wt %, 60 to 99.99 wt %, 70 to 99.99 wt %, 80 to 99.99 wt %, or even 90 to 99.99 wt %.

[0057] The glass transition temperature (Tg) of the binder resin may be 0°C or higher, 20°C or higher, 30°C or higher, 40°C or higher, 50°C or higher, 55°C or higher, or even 60°C or higher. The upper limit of Tg is, for example, 100°C or lower. In other words, the antistatic layer 2 may contain a binder resin having a Tg of 0°C or higher. According to the inventors' studies, when a binder resin is used, having the Tg of the binder resin within the above range can contribute to suppressing changes in the surface resistivity of the antistatic layer 2 before and after the DIN test. It is believed that a higher Tg of the binder resin suppresses thermal migration of the conductive material contained in the antistatic layer 2 and the resulting aggregation and orientation. Aggregation and orientation can improve the non-uniformity of the conductive material within the antistatic layer 2 and change the surface resistivity. According to the inventors' studies, increasing the non-uniformity of the CNTs tends to decrease the surface resistivity. The suppression of the change in surface resistivity based on the Tg of the binder resin may be due to the suppression of the migration of the conductive material during the heating cycle of the DIN test. Unless otherwise specified, the Tg of a polymer in this specification means the Tg calculated from the Fox formula based on the composition of the monomer components. Unless otherwise specified, the Tg of a resin (including a binder resin) in this specification means the Tg calculated by differential scanning calorimetry (DSC). The DSC measurement conditions are as follows: Atmospheric gas: nitrogen (50 mL / min) Measurement temperature range: 0°C → 100°C Heating rate: 10°C / min Sample amount: approximately 3 mg (for example, an aluminum Tzero pan can be used as the sample container).

[0058] When the antistatic layer 2 contains a binder having a Tg of 0° C. or higher, the proportion of the binder resin having a Tg of 0° C. or higher to all binder resins contained therein may be 50% by weight or higher, 55% by weight or higher, 60% by weight or higher, 65% by weight or higher, 70% by weight or higher, 75% by weight or higher, 80% by weight or higher, 85% by weight or higher, 90% by weight or higher, 91% by weight or higher, 92% by weight or higher, 93% by weight or higher, or even 94% by weight or higher. The upper limit of this proportion is, for example, 100% by weight or lower, and may be 99% by weight or lower, 98% by weight or lower, 97% by weight or lower, 96% by weight or lower, or even 95% by weight or lower.

[0059] The antistatic layer 2, particularly when it contains two or more types of binder resins, may contain a binder resin having a Tg of less than 0°C. For example, the antistatic layer 2 may contain a binder resin having a Tg of 0°C or higher and a binder resin having a Tg of less than 0°C. The lower limit of the Tg of the binder resin having a Tg of less than 0°C is, for example, -70°C or higher, and may be -60°C or higher, -50°C or higher, -45°C or higher, or even -40°C or higher. Depending on the composition of the antistatic layer 2, a binder resin having a Tg of less than 0°C may contribute to improving the film-forming properties of the antistatic layer 2 and the dispersibility of CNTs during film formation of the antistatic layer 2. When the antistatic layer 2 contains a binder resin having a Tg of 0° C. or higher and a binder resin having a Tg of lower than 0° C., the proportion of the binder resin having a Tg of lower than 0° C. to all the binder resins contained therein may be 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, 8% by weight or less, 6% by weight or less, or even 5% by weight or less. The lower limit of this proportion is, for example, 1% by weight or more, and may be 2% by weight or more, 3% by weight or more, 4% by weight or more, or even 5% by weight or more.

[0060] The antistatic layer 2 may contain a leveling agent. However, it is preferable that the content of the leveling agent in the antistatic layer 2 is small. According to the studies of the present inventors, not adding a leveling agent to the coating liquid for forming the antistatic layer 2 can contribute to reducing the absolute value of log B - log A in equation (1). The leveling agent may promote thermal migration of the conductive material contained in the antistatic layer 2. The content of the leveling agent may be less than 5 wt %, 4 wt % or less, 3 wt %, 2 wt % or less, 1 wt % or less, 0.5 wt % or less, or even 0.1 wt % or less. The antistatic layer 2 may be substantially free of a leveling agent. In this specification, "substantially free" means that the content is less than 0.01 wt %.

[0061] Non-uniformity of the conductive material contained in the antistatic layer 2 can affect the light transmittance of the optical stack 10. According to studies by the present inventors, as the non-uniformity of the CNTs, which are the conductive material, increases, the light transmittance of the optical stack 10 tends to decrease. From this perspective, the loss in total light transmittance of the optical stack 10 due to the antistatic layer 2 may be 1.0% or less. The loss in total light transmittance may be 0.90% or less, 0.80% or less, 0.70% or less, 0.60% or less, 0.50% or less, 0.45% or less, 0.40% or less, 0.35% or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, or even 0.10% or less. A lower loss in total light transmittance is preferable. The loss in total light transmittance can be determined by measuring the total light transmittance T2 of the optical laminate 10 to be evaluated and the total light transmittance T1 of an optical laminate having the same configuration except that it does not include the antistatic layer 2, and determining the difference (T1-T2) between the two. In this specification, total light transmittance means the transmittance of light in the wavelength range of 380 to 700 nm. The total light transmittance can be measured in accordance with the provisions of Japanese Industrial Standards (hereinafter referred to as JIS) K7361-1:1997. However, a D65 light source is used to measure the total light transmittance. Furthermore, light during measurement is incident from the optical film 3 side.

[0062] The thickness of the antistatic layer 2 is, for example, 5 to 1500 nm, and may be 1400 nm or less, 1300 nm or less, 1200 nm or less, 1100 nm or less, 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 180 nm or less, 150 nm or less, 120 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, or even 40 nm or less. The thickness may be 10 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 40 nm or more, or even 45 nm or more. According to the investigations of the present inventors, for antistatic layers 2 having the same composition and formed by the same method, the loss in total light transmittance tends to decrease as the thickness of the layer decreases.

[0063] The antistatic layer 2 may contain CNTs and a binder resin having a Tg of 0° C. or higher. In this case, the CNTs may have a length of 3 μm or more and 300 μm or less, and a diameter of 10 nm or less.

[0064] <Adhesive Sheet> The adhesive sheet 1 is typically a layer formed from an adhesive composition (I) containing a polymer (A).

[0065] (Polymer (A)) Examples of the polymer (A) are (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. The polymer (A) is preferably a (meth)acrylic polymer. The pressure-sensitive adhesive composition (I) may contain a (meth)acrylic polymer as a main component, in other words, the pressure-sensitive adhesive composition (I) may be an acrylic pressure-sensitive adhesive composition. In this specification, the term "main component" refers to the component having the largest content by weight in the composition. The content of the main component may be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 75% by weight or more, or even 80% by weight or more. In this specification, the term "(meth)acrylic polymer" refers to a polymer having a structural unit derived from a (meth)acrylic monomer such as (meth)acrylate. The content of the structural unit in the (meth)acrylic polymer is, for example, 40% by weight or more, and may be 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or even 95% by weight or more. The (meth)acrylic polymer may be composed only of structural units derived from (meth)acrylic monomers. (Meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0066] The polymer (A) may have a polyether structure. The pressure-sensitive adhesive composition (I) may contain the polymer (A) having a polyether structure as a main component. The polyether structure is a structure containing at least two ether groups (—O—). The polyether structure may be linear or branched. An example of the polyether structure contains an alkyl group, which may be linear or branched, and at least two ether groups. The polymer (A) may have the polyether structure in its main chain or in its side chain, preferably in its side chain. The polymer (A) may be a (meth)acrylic polymer having a polyether structure in its side chain.

[0067] The polymer (A) may have a structural unit having a polyether structure. In the structural unit, the polyether structure may be located in the main chain or in a side chain, preferably in the side chain. The polymer (A) may have a structural unit derived from a (meth)acrylic monomer having a polyether structure in the side chain.

[0068] The polymer (A) having a polyether structure in its side chain has, for example, a structural unit derived from a monomer A1 shown in the following formula (2). In other words, the polymer (A) may have a structural unit derived from a monomer shown in the following formula (2). R in formula (2) 1 is a hydrogen atom or a methyl group. 2 is an alkyl group which may be linear or branched, and is preferably a linear alkyl group. The number of carbon atoms in the alkyl group may be 1 to 10, or even 1 to 4. 2 Examples of R are a methyl group and an ethyl group. n is an integer of 1 to 15, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. When n is 1, the monomer A1 contains two ether groups, including the "-O-" of the COO group. The monomer A1 is a type of (meth)acrylic monomer, more specifically, a type of (meth)acrylate monomer. The R at the end of the side chain 2When focusing on the O group, the monomer A1 is also a type of alkoxy group-containing (meth)acrylate monomer. The structural unit derived from the monomer A1 has a polyether structure in the side chain.

[0069]

[0070] Examples of monomer A1 are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate, and preferably 2-methoxyethyl acrylate (MEA). The structural units derived from monomer A1 can contribute to a decrease in the surface resistivity of the PSA sheet 1 formed from the PSA composition (I).

[0071] The content of the structural unit having a polyether structure in polymer (A) may be, for example, 0% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, or even 50% by weight or more. The upper limit of this content may be, for example, 100% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, or even less than 60% by weight. In addition, the content of the structural unit derived from monomer A1 in polymer (A) may be within the above range.

[0072] The polymer (A) may not have a structural unit having a polyether structure.

[0073] The polymer (A) may have one or more types of structural units derived from the monomer A2. The monomer A2 may be copolymerizable with the monomer A1. The polymer (A) may have both a structural unit derived from the monomer A1 and a structural unit derived from the monomer A2.

[0074] An example of the monomer A2 is a (meth)acrylic monomer having an alkyl group having 1 to 30 carbon atoms on the side chain. The alkyl group may be linear or branched. Examples of the (meth)acrylic monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate (lauryl(meth)acrylate), n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, and octadecyl(meth)acrylate. The content of the structural unit derived from the (meth)acrylic monomer in the polymer (A) is, for example, 80% by weight or less, and may be 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, or even 5% by weight or less, or may even be 0% by weight (no such structural unit is present).

[0075] Another example of monomer A2 is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a hydroxyl group-containing (meth)acrylic monomer. Examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, as well as (4-hydroxymethylcyclohexyl)-methyl acrylate. From the viewpoint of improving the durability of the pressure-sensitive adhesive sheet 1 formed from the pressure-sensitive adhesive composition (I), 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred. The content of the structural units derived from the hydroxyl group-containing monomer in the polymer (A) is, for example, 1 to 5% by weight, and may be 3% by weight or less, or even 2% by weight or less. The polymer (A) may not necessarily have any structural units derived from the hydroxyl group-containing monomer.

[0076] Monomer A2 may be an aromatic ring-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, or an amide group-containing monomer.

[0077] The aromatic ring-containing monomer may be an aromatic ring-containing (meth)acrylic monomer. Examples of aromatic ring-containing monomers include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, hydroxyethylated β-naphthol (meth)acrylate, and biphenyl (meth)acrylate. Birefringence may occur due to misalignment of the pressure-sensitive adhesive sheet during the production and / or use of an image display device including the optical laminate 10. Birefringence may cause problems in the image display device, such as light leakage and display unevenness. The inclusion of a structural unit derived from an aromatic ring-containing monomer can contribute to reducing birefringence that may occur due to misalignment of the pressure-sensitive adhesive sheet.

[0078] The aromatic ring-containing monomer may be a monomer A3 shown in formula (3) below: 3 is a hydrogen atom or a methyl group. 4 is a phenyl group optionally substituted with a hydrogen atom, preferably a phenyl group. The substituent for the hydrogen atom is, for example, a linear or branched alkyl group having 1 to 10 carbon atoms, or even 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. n is an integer from 1 to 15, preferably an integer from 1 to 10, and more preferably an integer from 1 to 5. When n is 1, the monomer A3 is a type of (meth)acrylic monomer, more specifically a type of (meth)acrylate monomer. The monomer A3 contains two ether groups, including the "-O-" of the COO group. In other words, the structural unit derived from the monomer A3 is also a structural unit having a polyether structure. The content of the structural unit derived from the monomer A3 in the polymer (A) is included in the content of the structural unit having a polyether structure.

[0079]

[0080] An example of monomer A3 is phenoxyethyl (meth)acrylate.

[0081] The polymer (A) having a structural unit derived from the monomer A3 can contribute to improving the durability of the optical laminate 10. Furthermore, even when the optical laminate 10 includes an optical film 3 that can shrink when heated, the polymer (A) having a structural unit derived from the monomer A3 can contribute to suppressing displacement of the optical film 3 at the edge portions.

[0082] Examples of carboxyl group-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of amino group-containing monomers are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0083] Monomer A2 may be a polyfunctional monomer. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. Preferred polyfunctional acrylates are 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate.

[0084] The total content of structural units derived from aromatic ring-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, and polyfunctional monomers in polymer (A) is preferably 20% by weight or less, more preferably 15% by weight or less, even more preferably 10% by weight or less, and particularly preferably 8% by weight or less. When polymer (A) contains these structural units, the total content may be, for example, 0.01% by weight or more, 1% by weight or more, 2% by weight or more, or even 3% by weight or more. Polymer (A) may not have these structural units. In particular, the content of structural units derived from carboxyl group-containing monomers in polymer (A) may be less than 0.1% by weight, or even 0% by weight (i.e., the polymer does not have these structural units).

[0085] Examples of other monomers A2 include nitrile group-containing (meth)acrylates such as acrylic acid and (meth)acrylonitrile; epoxy group-containing monomers such as glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyltoluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene and isobutylene; vinyl ethers such as vinyl alkyl ether; and vinyl chloride.

[0086] The total content of structural units derived from other monomers A2 in polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, and is preferably 0% by weight (no such structural units are present).

[0087] The polymer (A) may have a structural unit derived from a (meth)acrylic monomer having a glass transition temperature (Tgh) in the range of −55° C. or higher when made into a homopolymer, a structural unit derived from a (meth)acrylic monomer having a Tgh in the range of −40° C. or higher, a structural unit derived from a (meth)acrylic monomer having a Tgh in the range of −30° C. or higher, or a structural unit derived from a (meth)acrylic monomer having a Tgh in the range of −10° C. or higher. Examples of the structural unit are a structural unit derived from monomer A3 and a structural unit derived from a (meth)acrylic monomer having an alkyl group with 1 to 3 carbon atoms in the side chain. The polymer (A) may have at least one structural unit selected from the group consisting of a structural unit derived from monomer A3 and a structural unit derived from a (meth)acrylic monomer having an alkyl group with 1 to 3 carbon atoms in the side chain. The polymer (A) having the above structural unit can contribute to improving the durability of the optical laminate 10.

[0088] The polymer (A) can be formed by polymerizing one or more of the above-mentioned monomers using a known method. A monomer and a partial polymer of the monomer may also be polymerized. The polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of forming a pressure-sensitive adhesive sheet with excellent optical transparency, solution polymerization and active energy ray polymerization are preferred. The polymerization is preferably carried out while avoiding contact between the monomer and / or the partial polymer and oxygen. For this purpose, for example, polymerization in an inert gas atmosphere such as nitrogen, or polymerization in a state where oxygen is blocked by a resin film or the like, can be employed. The polymer (A) formed may be in any form, such as a random copolymer, a block copolymer, or a graft copolymer.

[0089] The polymerization system for forming the polymer (A) may contain one or more polymerization initiators. The type of polymerization initiator can be selected depending on the polymerization reaction, and may be, for example, a thermal polymerization initiator or a photopolymerization initiator.

[0090] Examples of solvents used in solution polymerization include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

[0091] Examples of polymerization initiators used in solution polymerization include azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Examples of peroxide polymerization initiators include dibenzoyl peroxide and t-butyl permaleate. Among these, the azo polymerization initiators disclosed in JP-A-2002-69411 are preferred. Examples of such azo polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, or may be 0.1 to 0.3 parts by weight, per 100 parts by weight of the total amount of monomers.

[0092] The active energy rays used in the active energy ray polymerization include, for example, ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, as well as ultraviolet rays. The active energy ray is preferably ultraviolet rays. Polymerization by irradiation with ultraviolet rays is also called photopolymerization. The polymerization system for the active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for the active energy polymerization are not limited as long as the polymer (A) is formed.

[0093] Examples of the photopolymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator, although the photopolymerization initiator is not limited to the above examples.

[0094] Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. An example of a photoactive oxime-based photopolymerization initiator is 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. An example of a benzoin-based photopolymerization initiator is benzoin. An example of a benzyl-based photopolymerization initiator is benzil. An example of a benzophenone-based photopolymerization initiator is benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, or α-hydroxycyclohexyl phenyl ketone. An example of a ketal-based photopolymerization initiator is benzil dimethyl ketal. An example of a thioxanthone-based photopolymerization initiator is thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, or dodecylthioxanthone.

[0095] The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

[0096] The weight average molecular weight (Mw) of the polymer (A) is, for example, 1,000,000 to 3,000,000, and preferably 1,800,000 to 3,000,000. When the weight average molecular weight of the polymer (A) is 1,000,000 to 3,000,000, cracking of the PSA sheet can be suppressed, and an increase in viscosity and the occurrence of gelation tend to be suppressed. The weight average molecular weight (Mw) of the polymer in this specification is a value (polystyrene equivalent) based on measurement by GPC (gel permeation chromatography).

[0097] The content of the polymer (A) in the PSA composition (I) is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 75% by weight or more, or even 80% by weight or more, in terms of solid content. The upper limit of the content may be, for example, 99% by weight or less, 97% by weight or less, or even 95% by weight or less.

[0098] (Antistatic Agent) The pressure-sensitive adhesive composition (I) may contain an antistatic agent. The antistatic agent can contribute to reducing the surface resistivity of the pressure-sensitive adhesive sheet 1. Examples of the antistatic agent are ionic compounds such as salts. The ionic compound may be an ionic liquid that is liquid at room temperature (25°C).

[0099] Examples of ionic compounds include inorganic cation salts and organic cation salts. Examples of inorganic cation salts are inorganic cation-anion salts. Examples of cations contained in inorganic cation salts are alkali metal ions. Examples of alkali metal ions include lithium ions, sodium ions, and potassium ions, and preferably lithium ions. The inorganic cation salt may be a lithium salt.

[0100] Examples of anions contained in inorganic cation salts are Cl - ,Br - , I - , AlCl - , Al2Cl7 - , BF4 - , PF6 - , ClO - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3- , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , (CN)2N - , C4F9SO3 - , C3F7COO - , (CF3SO2)(CF3CO)N - , -O3S(CF2)3SO3 - and anions represented by the following general formulas (a) to (d): (a) (C n F 2n+1 SO2)2N - (n is an integer from 1 to 10) (b) CF2(C m F 2m SO2)2N - (c) —O3S(CF2) (where m is an integer from 1 to 10) l SO3 - (l is an integer from 1 to 10) (d) (C p F 2p+1 SO2)N - (C q F 2q+1 SO2) (p and q are each independently an integer from 1 to 10)

[0101] The anion contained in the inorganic cation salt is preferably a fluorine-containing anion, more preferably a fluorine-containing imide anion. An example of the fluorine-containing imide anion is an imide anion having a perfluoroalkyl group. A more specific example of the fluorine-containing imide anion is (CF3SO2)(CF3CO)N - or an anion represented by the above general formula (a), (b) or (d), preferably (CF3SO2)2N - , (C2F5SO2)2N - and more preferably (CF3SO2)2N - An example of a preferred inorganic cation salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0102] An example of an organic cation salt is an organic cation-anion salt. An example of a cation contained in the organic cation salt is an organic onium containing an organic group. Examples of oniums contained in the organic onium are nitrogen-containing oniums, sulfur-containing oniums, and phosphorus-containing oniums, and preferably nitrogen-containing oniums and sulfur-containing oniums. Examples of nitrogen-containing oniums are ammonium cation, piperidinium cation, pyrrolidinium cation, pyridinium cation, cations having a pyrroline skeleton, cations having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, and pyrazolinium cation. An example of a sulfur-containing onium is a sulfonium cation. An example of a phosphorus-containing onium is a phosphonium cation. Examples of organic groups contained in the organic onium are alkyl groups, alkoxyl groups, and alkenyl groups. Specific examples of preferred organic oniums are tetraalkylammonium cations (e.g., tributylmethylammonium cation), alkylpiperidinium cations, and alkylpyrrolidinium cations.

[0103] Examples of the anions contained in the organic cation salt are the same as the examples of the anions contained in the inorganic cation salt. Examples of preferred organic cation salts are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

[0104] The antistatic agent may be a combination of an inorganic cationic salt and an organic cationic salt, and preferably contains an organic cationic salt.

[0105] The amount of the antistatic agent in the pressure-sensitive adhesive composition (I) is, for example, 0.5 parts by weight or more, and may be 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, or even 4 parts by weight or more, relative to 100 parts by weight of the polymer (A). The upper limit of the amount is, for example, less than 30 parts by weight, and may be 20 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, or even 6 parts by weight or less, relative to 100 parts by weight of the polymer (A). By appropriately adjusting the amount of the antistatic agent in the pressure-sensitive adhesive composition (I), the durability of the pressure-sensitive adhesive sheet 1 can be further improved.

[0106] The surface resistivity of the adhesive sheet 1 is 1.0×10 13 Ω / □ or less, and may be 1.0×10 12 Ω / □ or less, 1.0×10 11 Ω / □ or less, 1.0×10 10 Ω / □ or less, 1.0×10 9 Ω / □ or less, 8.0×10 8 Ω / □ or less, 5.0×10 8 Ω / □ or less, 3.0×10 8 Ω / □ or less, 2.0×10 8 Ω / □ or less, 1.0×10 8 Ω / □ or less, 8.0×10 7 Ω / □ or less, 5.0×10 7 Ω / □ or less, and even 2.0×10 7 The lower limit of the surface resistivity may be, for example, 1.0 × 10 6 Ω / □ or more, and 1.0×10 7 Ω / □ or more, and even 1.0×10 8 The pressure-sensitive adhesive sheet 1 may have a surface resistivity in the above range before the DIN test, or may have a surface resistivity in the above range after the DIN test.

[0107] (Radical Scavenger) The PSA composition (I) may further contain a radical scavenger. Examples of the radical scavenger include various antioxidants such as hindered phenols, hindered amines, phosphites, phenols, thioethers, and blends of these antioxidants.

[0108] Types of antioxidants are, for example, radical chain inhibitors and peroxide decomposers.

[0109] The antioxidant may be at least one selected from hindered phenol-based, hindered amine-based, and phosphite-based antioxidants.

[0110] The hindered phenolic antioxidant may have a structure in which a tertiary butyl group is bonded to at least one carbon atom adjacent to the carbon atom on the aromatic ring to which the phenolic OH group is bonded. Examples of the hindered phenolic antioxidant include dibutylhydroxytoluene (BHT); Irganox 1010, Irganox 1010FF, Irganox 1035, Irganox 1035FF, Irganox 1076, Irganox 1076FD, Irganox 1076DWJ, Irganox 1098, Irganox 109 ... Irganox 1135, Irganox 1330, Irganox 1726, Irganox 1425WL, Irganox 1520L, Irganox 245, Irganox 245FF, Irganox 259, Irganox 3114, Irganox 565 and Irganox 295 (all of which are trade names manufactured by BASF).

[0111] The hindered amine antioxidant may have at least one hindered piperidine group in one molecule. Examples of the hindered amine antioxidant include Adeka STAB LA-63, Adeka STAB LA-63P, Adeka STAB LA-52, and Adeka STAB LA-57 (all of which are trade names, manufactured by ADEKA Corporation).

[0112] Examples of the phosphite antioxidants are triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite; and Adeka STAB 2112, Adeka STAB 2112RG, Adeka STAB 1178, and Adeka STAB 3010 (all of which are trade names, manufactured by ADEKA Corporation).

[0113] Examples of the phenolic antioxidants include monophenolic antioxidants, bisphenolic antioxidants, and polymeric phenolic antioxidants. Examples of the monophenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearin-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. Examples of the bisphenol antioxidant are 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane. Examples of the polymeric phenolic antioxidant are 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

[0114] Examples of thioether-based antioxidants are Adekastab AO-503 and Adekastab AO-26 (both are trade names, manufactured by ADEKA Corporation).

[0115] The molecular weight of the radical scavenger (e.g., antioxidant) may be 1,000 or less, 900 or less, 850 or less, 800 or less, 700 or less, 600 or less, 500 or less, 450 or less, or even 400 or less. The lower limit of the molecular weight is, for example, 100 or more. According to studies by the present inventors, radical scavengers having a molecular weight within the above range are particularly suitable for suppressing the amount of radicals generated in a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (I).

[0116] The radical scavenger (eg, antioxidant) may be a liquid at 25°C.

[0117] The amount of the radical scavenger in the pressure-sensitive adhesive composition (I) may be, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, or even 0.5 parts by weight or more, relative to 100 parts by weight of the polymer (A). The upper limit of the amount may be, for example, 15 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, 5 parts by weight or less, less than 5 parts by weight, 4 parts by weight or less, 3 parts by weight or less, or even 2 parts by weight or less, relative to 100 parts by weight of the polymer (A).

[0118] (Additives) The pressure-sensitive adhesive composition (I) may further contain materials other than those described above. Examples of such materials are additives. Examples of additives include crosslinking agents, silane coupling agents, colorants such as pigments and dyes, UV absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, softeners, polymerization inhibitors, rust inhibitors, inorganic fillers, organic fillers, powders such as metal powders, particles, and foil-like materials. The additives can be blended in a total amount of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 3 parts by weight or less, per 100 parts by weight of the polymer (A).

[0119] Examples of the crosslinking agent include an organic crosslinking agent and a polyfunctional metal chelate. Examples of the organic crosslinking agent include an isocyanate crosslinking agent, a peroxide crosslinking agent, an epoxy crosslinking agent, and an imine crosslinking agent. The organic crosslinking agent and the polyfunctional metal chelate can be used for both the solvent-based and active energy ray-curable pressure-sensitive adhesive composition (I). When the pressure-sensitive adhesive composition (I) is a solvent-based pressure-sensitive adhesive composition, the crosslinking agent is preferably a peroxide crosslinking agent or an isocyanate crosslinking agent. A peroxide crosslinking agent and an isocyanate crosslinking agent may be used in combination. The pressure-sensitive adhesive composition (I) may contain an isocyanate crosslinking agent, a peroxide crosslinking agent, or both an isocyanate crosslinking agent and a peroxide crosslinking agent.

[0120] Examples of isocyanate-based crosslinking agents include aromatic isocyanate compounds such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and polymethylene polyphenyl isocyanate; alicyclic isocyanate compounds such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and isophorone diisocyanate; and aliphatic isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. The isocyanate-based crosslinking agent may be a compound (adduct) obtained by adding the above isocyanate compound to a polyhydric alcohol compound such as trimethylolpropane; a compound obtained by addition reaction of the above isocyanate compound with a polyol such as polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, and polyisoprene polyol; or a derivative of the above isocyanate compound, such as an isocyanurate. Specific examples of the derivatives include a trimethylolpropane / tolylene diisocyanate trimer adduct (e.g., Coronate L, manufactured by Tosoh Corporation), a trimethylolpropane / hexamethylene diisocyanate trimer adduct (e.g., Coronate HL, manufactured by Tosoh Corporation), and an isocyanurate of hexamethylene diisocyanate (e.g., Coronate HX, manufactured by Tosoh Corporation).

[0121] When the pressure-sensitive adhesive composition (I) contains an isocyanate-based crosslinking agent, the amount thereof is, for example, 0.1 to 10 parts by weight, or may be 0.2 to 5 parts by weight, 0.25 to 3 parts by weight, 0.3 to 1 part by weight, or even 0.3 to 0.5 parts by weight, relative to 100 parts by weight of the polymer (A).

[0122] Examples of peroxide-based crosslinking agents include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, and 1,1-di(t-hexylperoxy)cyclohexane. The peroxide-based crosslinking agent may be benzoyl peroxide because of its excellent crosslinking reaction efficiency.

[0123] When the pressure-sensitive adhesive composition (I) contains a peroxide-based crosslinking agent, the blending amount thereof is, for example, 0.005 to 5 parts by weight, and may also be 0.01 to 3 parts by weight, 0.05 to 2 parts by weight, 0.07 to 1 part by weight, 0.07 to 0.5 parts by weight, 0.07 to 0.3 parts by weight, or even 0.07 to 0.2 parts by weight, relative to 100 parts by weight of the polymer (A).

[0124] Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

[0125] When the pressure-sensitive adhesive composition (I) contains a silane coupling agent, the blending amount thereof is, for example, 5 parts by weight or less, and may be 3 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or even 0.05 parts by weight or less, relative to 100 parts by weight of the polymer (A). The pressure-sensitive adhesive composition (I) does not have to contain a silane coupling agent.

[0126] The type of the pressure-sensitive adhesive composition (I) is, for example, an emulsion type, a solvent type (solution type), an active energy ray curable type (photocurable type), or a hot melt type (hot melt type). From the viewpoint of being able to form a pressure-sensitive adhesive sheet with excellent durability, the pressure-sensitive adhesive composition (I) may be a solvent type or an active energy ray curable type, or may be a solvent type. The solvent-type pressure-sensitive adhesive composition (I) may not contain a photocuring agent such as an ultraviolet curing agent.

[0127] (Optical Film) The optical film 3 includes, for example, at least one selected from the group consisting of a polarizing film and a retardation film. The optical film 3 may include a polarizing film. The optical film 3 may be a laminated film including a polarizing film and / or a retardation film. The optical film 3 may include a glass film.

[0128] The polarizing film includes a polarizer. The polarizing film includes a polarizer and a protective film (transparent protective film) arranged on at least one side of the polarizer. The protective film is usually arranged in contact with the main surface of the polarizer. The polarizer may be arranged between two protective films. A protective film may be arranged on each of both sides of the polarizer. The protective film may be a single layer or a laminate of two or more layers.

[0129] The polarizer is not particularly limited, and examples thereof include a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, which has been uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye; a polyene-based oriented film such as a dehydrated polyvinyl alcohol or a dehydrochlorinated polyvinyl chloride; etc. A polarizer typically comprises a polyvinyl alcohol film (polyvinyl alcohol films include an ethylene-vinyl acetate copolymer partially saponified film) and a dichroic substance such as iodine.

[0130] The thickness of the polarizer is not particularly limited and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the polarizer thickness is not particularly limited and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, a thickness of 20 μm or less) is suppressed in dimensional change and can contribute to improving the durability of the optical laminate, particularly durability at high temperatures.

[0131] The material for the protective film may be, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture-blocking properties, isotropy, etc. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material for the protective film may be a thermosetting resin or an ultraviolet-curable resin such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone-based resin. When the polarizing film has two protective films, the materials of the two protective films may be the same or different. For example, a protective film made of a thermoplastic resin may be bonded to one main surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curable resin may be bonded to the other main surface of the polarizer. The protective film may contain one or more optional additives, such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

[0132] The moisture permeability of the protective film is not particularly limited, and is 200 g / (m 2 · day) or less, and 2-day) or less. In this case, it is possible to prevent moisture in the air from penetrating into the polarizing film, and to suppress changes in the moisture content of the polarizing film. This makes it possible to suppress curling and dimensional changes in the polarizing film. Furthermore, when a protective film whose moisture permeability is limited to the above range is placed between the pressure-sensitive adhesive sheet 1 and the polarizer, it can contribute to inhibiting the migration of radicals from the pressure-sensitive adhesive sheet 1 at high temperatures. Examples of materials for forming a protective film with low moisture permeability include polyester-based polymers, polycarbonate-based polymers, arylate-based polymers, amide-based polymers, olefin-based polymers, cyclic olefin-based polymers, (meth)acrylic polymers, and mixtures thereof.

[0133] The moisture permeability of a protective film can be measured by the following method in accordance with the moisture permeability test (cup method) of JIS Z0208:1976. First, a protective film is cut to a diameter of 60 mm to prepare a measurement sample. Next, the measurement sample is placed in a moisture permeability cup containing approximately 15 g of calcium chloride. This moisture permeability cup is placed in an incubator set at a temperature of 40°C and a humidity of 92% RH, and left for 24 hours to perform a moisture permeability test. The moisture permeability of the protective film can be determined by measuring the increase in weight of calcium chloride before and after the test.

[0134] The thickness of the protective film can be determined as appropriate, but is generally about 10 to 200 μm in view of strength, workability such as handling, thinness, and the like.

[0135] The polarizer and the protective film are usually adhered to each other via an aqueous adhesive. Examples of aqueous adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex, aqueous polyurethane, and aqueous polyester. Examples of adhesives other than the above-mentioned adhesives include ultraviolet-curable adhesives and electron beam-curable adhesives. Electron beam-curable polarizing plate adhesives exhibit suitable adhesiveness to various protective films. The adhesive may contain a metal compound filler.

[0136] In the polarizing film, a retardation film or the like can be formed on the polarizer instead of the protective film. Another protective film or a retardation film or the like can be further provided on the protective film.

[0137] A polarizing film can be identified as a laminate that includes polarizers and includes layers bonded together with an adhesive.

[0138] The protective film may have a hard coat layer on the surface opposite to the surface bonded to the polarizer, and may also be subjected to treatments for purposes such as anti-reflection, anti-sticking, diffusion, and anti-glare.

[0139] The polarizing film may be a circular polarizing film.

[0140] The curl diameter of the polarizing film evaluated using the following test method may be 3 mm or more, 4 mm or more, 5 mm or more, 5.5 mm or more, 6 mm or more, 6.5 mm or more, 7 mm or more, or even 7.5 mm or more. A larger curl diameter indicates a polarizing film that is less likely to curl due to heat. Furthermore, the use of a polarizing film with a larger curl diameter is suitable, for example, for forming an antistatic layer 2 on the polarizing film, in order to increase the heating temperature while suppressing curling during formation. <Test Method> A polarizing film 51 is processed into a rectangular shape measuring 10 mm wide and 50 mm long, with the absorption axis of the polarizer aligned longitudinally, to prepare a test piece 52. Next, one longitudinal end 53a of the test piece 52 is fixed to the surface of an evaluation sheet 54 (see FIG. 2(a)). The upper surface of the test piece 52 is selected during fixation so that the other end 53b of the test piece 52 curls upward upon heating. Adhesive tape 56 can be used for fixing, but the fixing method is not limited as long as the end 53a does not peel off from the evaluation sheet 54 during the test. An example of the adhesive tape 56 is polyimide tape. Next, the entire test piece 52 is heated at 105°C for 12 hours to curl the test piece 52 from the other end 53b in the longitudinal direction of the test piece 52. The inner diameter of the cylindrical portion 55 of the test piece 52 formed by the curl is determined as the curl diameter (see Figure 2(b)).

[0141] The degree to which the test piece 52 curls can vary depending on the inherent thermal properties of the polarizing film 51. The inherent thermal properties of the polarizing film 51 vary depending on the layer structure of the polarizing film 51, the configuration, thickness, composition, etc. of each layer of the polarizing film 51. An example of an inherent thermal property is the bending moment M during heating, which will be described below.

[0142] The evaluation sheet 54 may be a sheet that does not undergo deformation such as curvature that would hinder evaluation of the curl diameter even when heated at 105°C for 12 hours. An example of the evaluation sheet 54 is a polystyrene sheet having a thickness of 5 mm.

[0143] The absolute value of the bending moment M of the polarizing film is 1×10 9 may be less than 1×10 8 Below, 5 x 10 7 Below, 1 x 10 7 Below, 8 x 10 6 Below, 5 x 10 6 Below, 4 x 10 6 Below, and further 3 x 10 6 The use of a polarizing film with a small bending moment M is suitable for, for example, when forming an antistatic layer 2 on the polarizing film, to increase the heating temperature during formation while suppressing curling.

[0144] A method for calculating the bending moment M will be described with reference to FIG. 3 . FIG. 3 is a cross-sectional view showing an example of a polarizing film 51. The polarizing film 51 in FIG. 3 has a structure in which a polarizer 61 is sandwiched between a pair of transparent protective films 62 and 63. The polarizer 61 is made of PVA and has a thickness of 22 μm. The transparent protective film 62 is made of triacetyl cellulose (TAC) and has a thickness of 40 μm. The transparent protective film 63 is made of an acrylic resin and has a thickness of 20 μm. Reference numeral 51C denotes a virtual plane located at the center of the thickness direction of the polarizing film 51 (hereinafter referred to as the central plane 51C). Reference numerals 61C, 62C, and 63C denote virtual planes located at the center of the thickness direction of each layer, respectively (hereinafter referred to as the central planes 61C, 62C, and 63C).

[0145] The expansion force P (P61 , P 62 , P 63 ) can be specified. The expansion force P of the layers other than the polarizer is defined by the formula: EtαΔT. The expansion force P of the polarizer is defined by the formula: EtβΔT. E is the storage modulus E of each layer at 23°C (unit: MPa), t is the thickness of each layer (unit: μm), α is the thermal expansion coefficient of each layer (unit: / °C), ΔT is the temperature difference from room temperature (23°C) during heating (unit: °C), and β is the dimensional change rate of the polarizer due to heating (105°C and 500 hours) (unit: %). The storage modulus E is a value determined by a tensile test. The tensile test is performed on a dumbbell-shaped test piece at a tensile speed of 300 mm / min. The E of the polarizer 61 is a value in the direction of the slow axis. The thermal expansion coefficient α is a value determined by thermomechanical analysis (TMA). TMA is performed at a measurement temperature of -40 to 85°C, with a sample size of 5 mm width and a chuck distance of 20 mm. ΔT is set to 67 (=90-23)° C. in consideration of the heating temperature when forming the antistatic layer 2. Note that the polarizer 61 usually shrinks in the direction of the slow axis when heated, so β ​​and the expansion force P 61 is usually a negative value.

[0146] The dimensional change rate β of the polarizer can be determined by measuring the change in dimension of the test piece before and after a heating test in which a polarizer with a pressure-sensitive adhesive layer is processed to a size of 10 cm x 10 cm, the test piece is attached to a glass plate, and the test piece is placed in an oven maintained at 105°C for 500 hours. The direction in which one side of the test piece extends is the direction of the absorption axis of the polarizer. The dimensional change rate β can be determined by the formula: dimensional change rate β = (W min -10) / 10×100(%). minis the length of the shortest side of the test piece after the heating test. A polarizer with a pressure-sensitive adhesive layer can be prepared as follows: A monomer mixture containing 99 parts by weight of butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate is charged into a four-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Next, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator is charged along with 100 parts by weight of ethyl acetate for 100 parts by weight of the monomer mixture. Next, nitrogen gas is introduced to replace the atmosphere while gently stirring the entire mixture, and the liquid temperature in the flask is maintained at around 55°C, allowing the polymerization reaction to proceed for 8 hours to prepare an acrylic polymer solution. The weight-average molecular weight of the acrylic polymer is approximately 1.8 million. Next, 0.03 parts by weight of a trimethylolpropane / xylylene diisocyanate adduct (e.g., Takenate D110N manufactured by Tosoh Corporation), 0.3 parts by weight of benzoyl peroxide, and 0.2 parts by weight of an epoxy group-containing silane coupling agent (e.g., KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) are blended with 100 parts by weight of the solids content of the prepared solution to prepare a pressure-sensitive adhesive composition. Next, the coated film of the prepared pressure-sensitive adhesive composition is dried at 155°C for 1 minute to prepare a pressure-sensitive adhesive layer having a thickness of 20 μm. A polarizer is bonded to the prepared pressure-sensitive adhesive layer to obtain a polarized film with the pressure-sensitive adhesive layer.

[0147] Furthermore, for each layer included in the polarizing film 51, the distance d (d 61 , d 62 , d 63 ) can be specified. The unit of the distance d is μm, and the sign of the distance d is defined as negative in the direction from one main surface 64A of the polarizing film 51 to the other main surface 64B. In the example of FIG. 3, the distance d 62 is negative, distance d 61 , d 63 is positive. The bending moment M can be determined as the sum of the products of the expansion forces P and d exhibited by the individual layers constituting the polarizing film 51. In the example of FIG. 3, the bending moment M=P 61 ×d 61 +P 62 ×d 62 +P 63 ×d 63is.

[0148] The polarizing film 51 typically has a multilayer structure including a polarizer. Even when the layer structure of the polarizing film 51 or the materials constituting each layer are different, the bending moment M can be calculated in the same manner. Note that the expansion force P generated in the hard coat layer is typically small and can be ignored in calculating the bending moment M.

[0149] The retardation film may be a film obtained by stretching a polymer film or a film obtained by aligning and fixing a liquid crystal material. The retardation film has birefringence, for example, in the in-plane and / or thickness direction.

[0150] Examples of the retardation film include anti-reflection retardation films (see JP 2012-133303 A,

[0221] ,

[0222] ,

[0228] ), viewing angle compensation retardation films (see JP 2012-133303 A,

[0225] ,

[0226] ), and tilted orientation retardation films for viewing angle compensation (see JP 2012-133303 A,

[0227] ).

[0151] The retardation film is not particularly limited in terms of, for example, retardation value, arrangement angle, three-dimensional birefringence, whether it is a single layer or a multilayer, etc., as long as it substantially has the above-mentioned functions, and a known retardation film can be used.

[0152] The thickness of the retardation film is preferably 20 μm or less, more preferably 10 μm or less, still more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

[0153] The retardation film is composed of, for example, two layers of a quarter-wave plate and a half-wave plate in which a liquid crystal material is oriented and fixed.

[0154] (Surface Resistivity of Optical Laminate) The optical laminate 10 may include a pressure-sensitive adhesive sheet 1, an antistatic layer 2, and an optical film 3 in this order, and may satisfy the following formula (4). In formula (4), C is the surface resistivity (unit: Ω / □) of the main surface 5 of the pressure-sensitive adhesive sheet 1 opposite the antistatic layer 2 in the optical laminate 10. In formula (4), D is the surface resistivity (unit: Ω / □) of the main surface 5 of the pressure-sensitive adhesive sheet 1 opposite the antistatic layer 2 in the optical laminate 10 that has undergone a DIN test (see FIG. 1 for the main surface 5). -1≦log D−log C≦2 (4)

[0155] According to the studies of the present inventors, a change in the resistance of the optical laminate 10 due to exposure to a harsh environment such as in an in-vehicle application can also be a cause of display defects. Furthermore, in an image display device incorporating a touch sensor, a change in the resistance of the optical laminate 10 can also be a cause of malfunction of the touch sensor.

[0156] The lower limit of log D - log C in formula (4) may be -0.9 or more, -0.8 or more, -0.7 or more, -0.6 or more, -0.5 or more, -0.4 or more, -0.35 or more, -0.3 or more, -0.25 or more, -0.2 or more, -0.15 or more, -0.1 or more, or even -0.05 or more. The upper limit of log D - log C may be 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, or even 0.05 or less.

[0157] In equation (4), log D - log C can vary depending on the composition of the pressure-sensitive adhesive sheet 1, the composition and formation method of the antistatic layer 2, and, if the optical laminate 10 includes a layer having antistatic properties other than the antistatic layer 2, the configuration of that layer. Examples of the composition of the pressure-sensitive adhesive sheet 1 include the type and content of the monomer used to form the pressure-sensitive adhesive sheet 1, and the type and content of additives such as antistatic agents contained in the pressure-sensitive adhesive sheet 1. Examples of the composition of the antistatic layer 2 include the type and content of the conductive material, and the type, content, and characteristics of materials contained other than the conductive material. Examples of materials contained other than the conductive material include binder resins and leveling agents. Examples of a method for forming the antistatic layer 2 include the composition and formation conditions of the coating liquid for forming the antistatic layer 2. An example of the composition of the coating liquid is the type of solvent. An example of a formation condition is the drying temperature of the coating liquid.

[0158] The surface resistivity C (surface resistivity before DIN test) of the optical laminate 10 is, for example, 1.0 × 10 12 Ω / □ or less, and 1.0×10 11 Ω / □ or less, 7.0×10 10 Ω / □ or less, 5.0×10 10 Ω / □ or less, 3.0×10 10 Ω / □ or less, 1.0×10 10 Ω / □ or less, 7.0×10 9 Ω / □ or less, 5.0×10 9 Ω / □ or less, 3.0×10 9 Ω / □ or less, 1.0×10 9 Ω / □ or less, 9.0×10 8 Ω / □ or less, 8.0×10 8 Ω / □ or less, 7.0×10 8 Ω / □ or less, 6.0×10 8 Ω / □ or less, 5.0×10 8 Ω / □ or less, 4.0×10 8 Ω / □ or less, 3.0×10 8 Ω / □ or less, 2.0×10 8 Ω / □ or less, 2.0×10 8 Ω / □ or less, 1.5 x 10 8 Ω / □ or less, 1.0×10 8 Ω / □ or less, 9.0×10 7 Ω / □ or less, 8.0×10 7Ω / □ or less, and even 7.5×10 7 The lower limit of the surface resistivity C may be, for example, 1.0 × 10 6 Ω / □ or more, and 5.0×10 6 Ω / □ or more, 1.0×10 7 Ω / □ or more, 2.0×10 7 Ω / □ or more, 3.0×10 7 Ω / □ or more, 4.0×10 7 Ω / □ or more, 5.0×10 7 Ω / □ or more, and even 6.0×10 7 It may be Ω / □ or more.

[0159] Examples of the range that the surface resistivity D (surface resistivity after DIN test) of the optical laminate 10 can take are the same as the examples of the range that the surface resistivity C can take.

[0160] The surface resistivity D may be the same as or greater than the surface resistivity C. In other words, the surface resistivity D and the surface resistivity C may have a relationship expressed by the formula: surface resistivity D ≧ surface resistivity C, or may have a relationship expressed by the formula: surface resistivity D = surface resistivity C.

[0161] The surface resistivities C and D can be determined by measuring the surface resistivity of the main surface 5 of the pressure-sensitive adhesive sheet 1 in the optical laminate 10. The surface resistivity can be measured using a high-resistance resistivity meter (for example, the Hiresta series manufactured by Mitsubishi Chemical Analytech Co., Ltd.) in accordance with the method defined in JIS K6911:1995. However, the surface resistivities C and D are measured at an applied voltage of 500 V, an application time of 30 seconds, and an ambient temperature of 25±3°C.

[0162] In light of the fact that a change in resistance of the optical laminate 10 due to exposure to a harsh environment, such as in an in-vehicle application, can be a cause of display defects and malfunction of a touch sensor, this embodiment discloses the following optical laminate. That is, an optical laminate different from the above of this embodiment may be an optical laminate that includes a pressure-sensitive adhesive sheet, an antistatic layer, and an optical film, in this order, and satisfies the following formula (4): -1≦log D−log C≦2 (4) where C in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate, and D is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate that has undergone a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220.

[0163] [Method for Producing Optical Laminate] The optical laminate 10 can be produced, for example, by producing a first laminate L1 comprising an optical film 3 and an antistatic layer 2, producing a second laminate L2 comprising a substrate and a pressure-sensitive adhesive sheet 1, and bonding the pressure-sensitive adhesive sheet 1 of the second laminate L2 to the antistatic layer 2 of the first laminate L1. However, the method for producing the optical laminate 10 is not limited to this example.

[0164] (Method for Producing Antistatic Layer 2 and First Laminate L1) First, a solution or dispersion of a conductive material is prepared. Examples of solvents for the solution or dispersion include water and organic solvents. The organic solvent may be water-soluble. The solvent may be a single solvent or a mixed solvent containing two or more solvents. An example of a mixed solvent is a solvent containing water and a water-soluble organic solvent. Examples of water-soluble organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol. The water-soluble organic solvent may be isopropanol (IPA). According to the inventors' studies, combining a conductive material with a single solvent can contribute to suppressing changes in the surface resistivity of the antistatic layer 2 before and after DIN testing. The single solvent is preferably water. Furthermore, according to the study, the use of a single solvent, particularly water, may contribute to improving the uniformity of the CNTs in the antistatic layer 2.

[0165] Next, a solution or dispersion of a conductive material is applied as a coating liquid to the surface of the optical film 3. The resulting coating film is dried to form an antistatic layer 2 on the optical film 3. This results in a first laminate L1 composed of the optical film 3 and the antistatic layer 2. Heating may be used in combination with the drying. When heating is used in combination, the drying temperature may be, for example, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, 90°C or higher, 95°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, or even 130°C or higher. The upper limit of the drying temperature is, for example, 160°C or lower. According to the inventors' studies, a drying temperature of 70°C or higher, preferably 80°C or higher, and more preferably 90°C or higher, can contribute to suppressing changes in the surface resistivity of the antistatic layer 2 before and after the DIN test. Furthermore, according to studies, a drying temperature of 70°C or higher, preferably 80°C or higher, and more preferably 90°C or higher may contribute to improving the uniformity of CNTs in the antistatic layer 2. On the other hand, if the drying temperature during formation of the antistatic layer 2 is too high, curling of the optical laminate 2 may occur easily. To suppress curling, the upper limit of the drying temperature may be set appropriately. While this may vary depending on the configuration of the optical film 3, the upper limit may be, for example, 160°C or less, 150°C or less, 140°C or less, 130°C or less, less than 130°C, 125°C or less, 120°C or less, 115°C or less, or even 110°C or less.

[0166] Focusing on the preparation of a preferred antistatic layer 2, this embodiment discloses the following manufacturing method. That is, the manufacturing method of the antistatic layer 2 according to this embodiment includes forming the antistatic layer 2 by drying a coating film of a coating liquid, such as a solution or dispersion, containing a conductive material and a single solvent. Preferred embodiments of the conductive material and the single solvent are as described above. The coating film can be formed, for example, on the surface of a substrate. The substrate can be, for example, a release film. The antistatic layer 2 formed on the release film can be transferred to, for example, an optical film. The substrate may be an optical film. The coating liquid may contain a material other than the conductive material, such as a binder resin. Preferred embodiments of the binder resin are as described above. The coating liquid can contain a leveling agent. However, the content of the leveling agent in the coating liquid is preferably small, as exemplified by the content examples described above in the description of the antistatic layer 2. The coating liquid may be substantially free of a leveling agent. The preferred drying temperature for the coating film is as described above. The drying temperature may be 70°C or higher and lower than 130°C.

[0167] The method for producing the antistatic layer 2 according to this embodiment includes drying a coating film of a coating liquid containing a conductive material at 70°C or higher and lower than 130°C to form the antistatic layer 2. The preferred drying temperature for the coating film is as described above. Examples of preferred aspects of the conductive material are as described above. The coating film can be formed, for example, on the surface of a substrate. The substrate can be, for example, a release film. The antistatic layer 2 formed on the release film can be transferred to, for example, an optical film. The substrate may be an optical film. The coating liquid may contain a material other than the conductive material, such as a binder resin. Examples of preferred aspects of the binder resin are as described above. The coating liquid can contain a leveling agent. However, the content of the leveling agent in the coating liquid is preferably low, as exemplified by the content examples described above in the description of the antistatic layer 2. The coating liquid may be substantially free of a leveling agent. The solvent contained in the coating liquid may be a single solvent. Examples of preferred aspects of the single solvent are as described above.

[0168] The method for manufacturing an optical laminate according to the present embodiment is a method for manufacturing an optical laminate including an adhesive sheet, an antistatic layer, and an optical film, and includes forming the antistatic layer by the method for manufacturing an antistatic layer 2 according to the present embodiment.

[0169] (Method for producing second laminate L2) The pressure-sensitive adhesive sheet 1 is formed from a pressure-sensitive adhesive composition (I). The pressure-sensitive adhesive sheet 1 contains, for example, a crosslinked product of a (meth)acrylic polymer. The pressure-sensitive adhesive sheet 1 is formed from the pressure-sensitive adhesive composition (I) by the following method.

[0170] The pressure-sensitive adhesive sheet 1 can be formed, for example, by applying the pressure-sensitive adhesive composition (I) to a substrate to form a coating film, and then drying the resulting coating film, thereby obtaining a second laminate L2 consisting of the substrate and the pressure-sensitive adhesive sheet 1.

[0171] The substrate may be, for example, a release film. The pressure-sensitive adhesive sheet 1 formed on the release film may be transferred to, for example, an optical film. The substrate may be an optical film.

[0172] After the pressure-sensitive adhesive sheet 1 is transferred to the antistatic layer 2, the release film can be used as a release film until the pressure-sensitive adhesive sheet 1 is put to practical use. In this case, the process can be simplified.

[0173] Examples of materials constituting the release film include suitable thin sheets such as porous materials such as plastic film, paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof, but plastic film is preferably used because of its excellent surface smoothness.

[0174] The plastic film is not particularly limited, and examples thereof include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, and ethylene-vinyl acetate copolymer film.

[0175] The thickness of the release film is usually 5 to 200 μm, and preferably about 5 to 100 μm. The release film is subjected to a release treatment using, for example, a silicone-based, fluorine-based, or long-chain alkyl-based release agent. The release film may be subjected to a release treatment using a fatty acid amide-based release agent, silica powder, or the like, an antifouling treatment, or various antistatic treatments such as coating-type, kneading-type, and vapor deposition-type.

[0176] A solution (adhesive solution) containing the adhesive composition (I) may be applied to the substrate. The solids concentration of the adhesive solution is, for example, 5 to 50 wt %, preferably 10 to 40 wt %. The adhesive solution may be prepared by appropriately adding the same solvent as the polymerization solvent or a different solvent to the adhesive composition (I), depending on the polymerization form of the (meth)acrylic polymer (A).

[0177] Various methods can be used to apply the pressure-sensitive adhesive composition (I) to a substrate, including, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater, etc. The amount of pressure-sensitive adhesive composition (I) to be applied can be adjusted appropriately depending on the desired thickness of the pressure-sensitive adhesive sheet 1.

[0178] The coating film hardens by drying, forming the pressure-sensitive adhesive sheet 1. The drying temperature for the coating film is, for example, 130°C or lower, preferably 125°C or lower, more preferably 120°C or lower, even more preferably 110°C or lower, and particularly preferably 100°C or lower. The drying temperature for the coating film may be 60°C or higher, or may be 80°C or higher. A drying temperature of 60°C or higher can, for example, smoothly promote the reaction of the isocyanate-based crosslinking agent, thereby contributing to improving the cohesive strength of the pressure-sensitive adhesive sheet 1. A drying temperature of 130°C or lower can, for example, appropriately adjust the reaction rate of the isocyanate-based crosslinking agent, thereby contributing to improving the transparency of the pressure-sensitive adhesive sheet 1.

[0179] The drying time of the coating film can be adjusted appropriately depending on the composition of the pressure-sensitive adhesive composition (I), and is preferably 30 to 300 seconds, more preferably 40 to 240 seconds, and particularly preferably 60 to 180 seconds.

[0180] The thickness of the pressure-sensitive adhesive sheet 1 is not particularly limited, and may be 2 to 150 μm, 2 to 100 μm, or 5 to 50 μm. Appropriately adjusting the thickness of the pressure-sensitive adhesive sheet 1 can contribute to improving the adhesion between the pressure-sensitive adhesive sheet 1 and the antistatic layer 2. Appropriately adjusting the thickness of the pressure-sensitive adhesive sheet 1 can also contribute to preventing peeling of the pressure-sensitive adhesive sheet 1 from an adherend such as glass or an image display device.

[0181] Next, the pressure-sensitive adhesive sheet 1 of the second laminate L2 and the antistatic layer 2 of the first laminate L1 are bonded together, thereby obtaining a laminate comprising the optical film 3, the antistatic layer 2, the pressure-sensitive adhesive sheet 1, and the substrate.

[0182] Figure 4 is a cross-sectional view schematically showing another example of the optical laminate of this embodiment. The optical laminate 10 (10B) in Figure 4 has a laminated structure in which a release liner 4, a pressure-sensitive adhesive sheet 1, an antistatic layer 2, and an optical film 3 are laminated in this order. After peeling off the release liner 4, the optical laminate 10B can be used by being attached to, for example, an image display cell.

[0183] Examples of materials that can be used to form the release liner 4 include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film; porous materials such as paper, cloth, and nonwoven fabric; and appropriate thin sheets such as nets, foam sheets, metal foils, and laminates of these. However, plastic films are preferred because of their excellent surface smoothness.

[0184] The plastic film is not particularly limited as long as it is a film that can protect the adhesive sheet 1, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

[0185] The thickness of the release liner 4 is usually 5 to 200 μm, and preferably about 5 to 100 μm. The release liner 4 may be subjected to various treatments such as release treatment, antifouling treatment, and antistatic treatment as necessary. For the release treatment and antifouling treatment, various release agents such as silicone-based, fluorine-based, long-chain alkyl-based, and fatty acid amide-based release agents, as well as particles such as silica powder, can be used. The antistatic treatment may be of the coating type, kneading type, or vapor deposition type. To improve the releasability of the PSA sheet 1, it is particularly suitable to apply a release treatment to the surface of the release liner 4.

[0186] The release film used to form the pressure-sensitive adhesive sheet 1 may also be used as the release liner 4 .

[0187] The optical laminate of this embodiment may include additional layers and / or films other than those described above.

[0188] The optical laminate of this embodiment can be distributed and stored, for example, as a rolled body obtained by rolling up a strip-shaped optical laminate, or as a sheet-shaped optical laminate. The optical laminate of this embodiment is suitable for use in image display devices used in environments where static electricity is particularly likely to occur, particularly in vehicle-mounted displays. Examples of vehicle-mounted displays include panels for car navigation devices, cluster panels, and mirror displays. Cluster panels are panels that display the vehicle's traveling speed, engine rotation speed, etc.

[0189] [Image display panel] An example of an image display panel of this embodiment is shown in Fig. 5. The image display panel 11 (11A) in Fig. 5 includes an optical laminate 10A and further includes an image display cell 30A. The optical laminate 10A is bonded to the image display cell 30A via an adhesive sheet 1.

[0190] The image display cell 30A includes an image forming layer 32, a first transparent substrate 31, and a second transparent substrate 33. The image forming layer 32 is disposed between the first transparent substrate 31 and the second transparent substrate 33, and is in contact with each of the first transparent substrate 31 and the second transparent substrate 33. The adhesive sheet 1 is in contact with the first transparent substrate 31.

[0191] The image forming layer 32 is, for example, a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field. A liquid crystal layer containing the above liquid crystal molecules is suitable for an IPS (In-Plane-Switching) mode. However, the liquid crystal layer may also be used in a TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, π type, VA (Vertical Alignment) type, or the like. The image forming layer 32 may also be an EL light-emitting layer.

[0192] The thickness of the image forming layer 32 is, for example, 1.5 μm to 4 μm.

[0193] Examples of materials for the first transparent substrate 31 and the second transparent substrate 33 include glass and polymer. Examples of polymers that make up the transparent substrates include polyethylene terephthalate, polycycloolefin, and polycarbonate. The thickness of a transparent substrate made of glass is, for example, 0.1 mm to 1 mm. The thickness of a transparent substrate made of polymer is, for example, 10 μm to 200 μm.

[0194] The image display cell 30A may further include layers other than the image forming layer 32, the first transparent substrate 31, and the second transparent substrate 33. Examples of such layers include a color filter, an easy-adhesion layer, and a hard coat layer. The color filter is, for example, disposed closer to the viewing side than the image forming layer 32, and is preferably located between the first transparent substrate 31 and the pressure-sensitive adhesive sheet 1. The easy-adhesion layer and the hard coat layer are, for example, disposed on the surface of the first transparent substrate 31 and / or the second transparent substrate 33.

[0195] The image display panel 11A may further include other components in addition to the optical stack 10A and the image display cell 30A. As an example, the image display panel 11A may further include a conductive structure (not shown) electrically connected to the side surface of the optical stack 10A. Connecting the conductive structure to earth makes it easier to suppress static charging of the optical stack 10A. The conductive structure may cover the entire side surface of the optical stack 10A, or may cover only a portion of the side surface of the optical stack 10A. The ratio of the area of ​​the side surface of the optical stack 10A covered by the conductive structure to the entire area of ​​the side surface of the optical stack 10A is, for example, 1% or more, and preferably 3% or more.

[0196] Examples of materials for the conductive structure include conductive pastes made of metals such as silver and gold, conductive adhesives, and other conductive materials. The conductive structure may be wiring extending from the side surfaces of the optical laminate 10A.

[0197] The image display panel 11A may further include other optical films in addition to the optical film 3. Examples of other optical films include films used in image display devices, such as polarizing films, reflective films, anti-transmitting films, viewing angle compensation films, and brightness enhancement films. The image display panel 11A may include one or more types of other optical films.

[0198] When the other optical film is a polarizing film, the polarizing film may be bonded to the second transparent substrate 33 of the image display cell 30A. The polarizing film as the other optical film may have the same configuration as the polarizing film as the optical film 3. The polarizers of the polarizing film as the optical film 3 and the polarizing film as the other optical film may have transmission axes (or absorption axes) of their polarizers perpendicular to each other. A pressure-sensitive adhesive sheet can be used for bonding to the second transparent substrate 33. This pressure-sensitive adhesive sheet may be the pressure-sensitive adhesive sheet 1. The thickness of the pressure-sensitive adhesive sheet used for bonding to the second transparent substrate 33 may be, for example, 1 to 100 μm, 2 to 50 μm, 2 to 40 μm, or even 5 to 35 μm.

[0199] Another example of the image display panel of this embodiment is shown in Figure 6. The image display panel 11 (11B) of Figure 6 has the same configuration as the image display panel 11A, except that it further includes a conductive layer 40 disposed between the optical laminate 10A and the image display cell 30A. However, the image display panel of this embodiment does not necessarily include the conductive layer 40. Not including the conductive layer 40 can contribute to suppressing the reflectance of the image display panel, in other words, improving the visibility of the image display device. In the image display panel 11A that does not include the conductive layer 40, it is preferable to provide a conductive portion (the above-mentioned conductive structure) adjacent to the adhesive sheet 1. For example, a conductive silver paste can be used for the conductive portion.

[0200] The conductive layer 40 includes, for example, a conductive agent. Known materials such as metal oxides and conductive polymers can be used as the conductive agent. The thickness of the conductive layer 40 is, for example, 5 nm to 180 nm. The surface resistivity of the conductive layer 40 is, for example, 1.0×10 6 Ω / □ to 1.0 x 10 10 Ω / □, preferably 1.0×10 7 Ω / □ to 1.0 x 10 9 It is Ω / □.

[0201] The image display panel of this embodiment may have a built-in touch sensing function. An example of an image display panel having a built-in touch sensing function is shown in FIG. 7 . The image display panel 11 (11C) of FIG. 7 has the same configuration as the image display panel 11A, except that the image display cell 30B further includes a touch sensing electrode unit 35. The touch sensing electrode unit 35 is disposed between the first transparent substrate 31 and the second transparent substrate 33. The touch sensing electrode unit 35 has touch sensor and touch drive functions. The image display panel 11C is a so-called in-cell image display panel, and the image display cell 30B is a so-called in-cell image display cell. However, the touch sensing electrode unit 35 may be disposed closer to the viewer than the first transparent substrate 31. In other words, the image display panel 11C may be a so-called on-cell image display panel, and the image display cell 30B may be a so-called on-cell image display cell.

[0202] The touch sensing electrode unit 35 includes a touch sensor electrode 36 and a touch drive electrode 37. The touch sensor electrode 36 refers to a (receiving) electrode for touch detection. The touch sensor electrode 36 and the touch drive electrode 37 can be formed independently in various patterns. For example, when the image display cell 30B is flat, the touch sensor electrode 36 and the touch drive electrode 37 can be provided independently in the X-axis direction and the Y-axis direction, respectively, and can be formed in a pattern in which they intersect at right angles. In FIG. 7 , in the touch sensing electrode unit 35, the touch sensor electrode 36 is arranged closer to the viewing side than the touch drive electrode 37. The touch drive electrode 37 may also be arranged closer to the viewing side than the touch sensor electrode 36. In the touch sensing electrode unit 35, the touch sensor electrode 36 and the touch drive electrode 37 may be integrated.

[0203] 7 is disposed between the image forming layer 32 and the first transparent substrate 31 (on the viewing side of the image forming layer 32). However, the touch sensing electrode unit 35 may also be disposed between the image forming layer 32 and the second transparent substrate 33 (on the lighting system side of the image forming layer 32).

[0204] In the touch sensing electrode unit 35, the touch sensor electrode 36 and the touch drive electrode 37 do not need to be in contact with each other. For example, the touch sensor electrode 36 may be disposed between the image forming layer 32 and the first transparent substrate 31, and the touch drive electrode 37 may be disposed between the image forming layer 32 and the second transparent substrate 33.

[0205] The drive electrode (touch drive electrode 37 or an electrode in which the touch sensor electrode 36 and the touch drive electrode 37 are integrated) in the touch sensing electrode portion 35 can also serve as a common electrode that controls the image forming layer 32.

[0206] The touch sensor electrode 36 (capacitive sensor), the touch drive electrode 37, or an electrode formed by integrating these electrodes, which constitute the touch sensing electrode unit 35, function as a transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and examples thereof include metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, and tungsten, as well as alloys thereof. The material of the transparent conductive layer may be an oxide of a metal such as indium, tin, zinc, gallium, antimony, zirconium, or cadmium. Specific examples of oxides include indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. The material of the transparent conductive layer may also be a metal compound such as copper iodide. The material of the transparent conductive layer is preferably indium oxide (ITO) containing tin oxide or tin oxide containing antimony, with ITO being particularly preferred. When the material of the transparent conductive layer is ITO, it is preferable that the content of indium oxide in the transparent conductive layer is 80 to 99% by weight and the content of tin oxide is 1 to 20% by weight.

[0207] The electrodes constituting the touch sensing electrode unit 35 (the touch sensor electrodes 36, the touch drive electrodes 37, or an electrode formed by integrating these) can be formed as a transparent electrode pattern between the first transparent substrate 31 and the second transparent substrate 33 by a conventional method. The transparent electrode pattern is electrically connected, for example, to wiring lines formed at the ends of the transparent substrates. The wiring lines are connected, for example, to a controller IC. The transparent electrode pattern can have any shape depending on the application, such as a comb shape, a stripe shape, or a diamond shape. The thickness of the transparent electrode pattern is, for example, 10 nm to 100 nm. The width of the transparent electrode pattern is, for example, 0.1 mm to 5 mm.

[0208] [Embodiment of Image Display Device] The image display device of this embodiment includes, for example, an image display panel 11A and an illumination system. Note that, instead of the image display panel 11A, an image display panel 11B or an image display panel 11C can also be used. In the image display device, the image display panel 11A is, for example, disposed closer to the viewing side than the illumination system. The illumination system has, for example, a backlight or a reflector, and irradiates light onto the image display panel 11A.

[0209] The image display device of this embodiment may be an organic EL display or a liquid crystal display. However, the image display device is not limited to this example. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), or the like. The image display device may be used for home appliances, in-vehicle applications, public information displays (PID), or the like, and may be an in-vehicle display.

[0210] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0211] [Preparation of First Laminate L1 Comprising Antistatic Layer and Polarizing Film] <Preparation of Coating Liquid for Forming Antistatic Layer> (Coating Liquids A1 to A6) 0.05 parts by weight of CNTs (manufactured by OCSiAL, TUBALL 01RW02, single layer) having an average length of 5 μm and a diameter of approximately 1.6 nm, 0.6 parts by weight of a dispersant (manufactured by BASF, product name: Pluronic F-108, HLB: 24 or more), 30 parts by weight of ethanol, and 70 parts by weight of pure water were placed in a glass beaker, and a dispersion treatment was carried out using an ultrasonic homogenizer at 50 W and a frequency of 30 kHz for 30 minutes to obtain a CNT dispersion with a solid content of 1.0 wt %. Next, the resulting CNT dispersion, binder resin, and, if necessary, leveling agent were mixed in the solids weight ratio shown in Table 1 below, and the entire mixture was diluted with pure water or a mixed solvent of pure water and isopropyl alcohol (IPA) (volume ratio 1:1) to obtain a solids content of 2 wt%. Coating Solutions A1 to A6 were prepared. The CNT lengths ranged from 3 μm to 300 μm. The binder resins used were Jurimmer FC-80 manufactured by Toagosei (listed as acrylic in Table 1, solids content 30 wt%, Tg 50°C) and Superflex 650 manufactured by Dai-ichi Kogyo Seiyaku (listed as urethane in Table 1, solids content 26 wt%, Tg -15°C). The leveling agent used was Emulmin 240, a polyether-based leveling agent manufactured by Sanyo Chemical Industries. The types of binder resin and leveling agent were the same as those used for Coating Solution A7.

[0212] (Coating Solution A7) 0.08 parts by weight of CNTs (ZEON NanoTechnologies, ZEONANO SG101, single-walled) with an average length of 300 μm and a diameter of approximately 4 nm, 0.7 parts by weight of a dispersant (BASF, product name: Pluronic F-108, HLB: 24 or higher), 30 parts by weight of ethanol, and 70 parts by weight of pure water were placed in a glass beaker and dispersed using an ultrasonic homogenizer at 50 W and a frequency of 30 kHz for 30 minutes to obtain a CNT dispersion with a solid content of 1.0 wt%. Next, the obtained CNT dispersion, a binder resin, and a leveling agent were mixed in the solid content weight ratio shown in Table 1 below, and the whole was diluted with pure water to obtain a solid content of 2 wt% to produce Coating Solution A7.

[0213] (Coating Solution A8) 14.3 parts by weight of a thiophene-based polymer-containing solution (PEDOT / PSS-NH4), 1 part by weight of binder resin solution A (Superflex 210 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., containing urethane resin, solids content 35 wt%), 4 parts by weight of binder resin solution B (Epocross WS-700 manufactured by Nippon Shokubai Co., Ltd., containing acrylic resin with oxazoline groups, solids content 25 wt%), triethylene glycol, and water were mixed to obtain Coating Solution A8 with a solids concentration of 1.5 wt%. The thiophene-based polymer-containing solution was prepared by neutralizing an aqueous dispersion containing poly(3,4-ethylenedioxythiophene) (PEDOT) and sodium polystyrene sulfonate (PSS) (CleviosP manufactured by Heraeus Co., Ltd.) with aqueous ammonia to a solids content of 1 wt%. Triethylene glycol was mixed so that its content in Coating Solution A8 was 3 wt%. Coating liquid A8 contained 0.14 wt % of a thiophene-based polymer, 0.36 wt % of a urethane resin binder, and 1.0 wt % of an acrylic resin binder.

[0214] (Coating Liquids A9 to A11) Coating Liquids A9 to A11 were prepared in the same manner as Coating Liquids A1 to A6, except that a mixture of Toagosei's JURYMER FC-80 (listed as acrylic in Table 1, solids content 30% by weight, Tg 50°C) and Dai-ichi Kogyo Seiyaku's SUPERFLEX 650 (listed as urethane in Table 1, solids content 26% by weight, Tg -15°C) was used as the binder resin. The mixing ratio of JURYMER FC-80 and SUPERFLEX 650 was adjusted to obtain the solids ratio shown in Table 1 below.

[0215] The coating liquids are summarized in Table 1.

[0216]

[0217] <Preparation of Polarizing Film> (Preparation of Protective Film A with Hard Coat Layer) A resin solution (manufactured by DIC Corporation, product name: Unidic 17-806, solids concentration: 80%) in which an ultraviolet-curable resin monomer or oligomer containing urethane acrylate as a main component was dissolved in butyl acetate was prepared. Next, 5 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, product name: IRGACURE 907) and 0.1 parts by weight of a leveling agent (manufactured by DIC Corporation, product name: GRANDIC PC4100) were added to 100 parts by weight of the solids content of the resin solution. Next, cyclopentanone and propylene glycol monomethyl ether were added to the resin solution in a weight ratio of 45:55 so that the solids concentration of the resin solution was adjusted to 36% by weight, thereby preparing a hard coat layer-forming material. Next, the prepared forming material was applied onto a transparent protective film containing triacetyl cellulose (TAC film manufactured by Konica Minolta, product name "KC4UY", thickness 40 μm) to form a coating film. The thickness of the coating film was adjusted so that the thickness of the hard coat layer obtained by curing the forming material was 7 μm. Next, the coating film was dried at 90 ° C for 1 minute, and further irradiated with a high-pressure mercury lamp with an integrated light intensity of 300 mJ / cm. 2 The coating film was irradiated with ultraviolet light of 1000 kJ / cm. This cured the coating film, and a protective film A (thickness: 47 μm) with a hard coat layer (HC) was obtained.

[0218] (Preparation of Polarizer A) A polyvinyl alcohol (PVA) film having an average degree of polymerization of 2400, a degree of saponification of 99.9 mol%, and a thickness of 45 μm was immersed in a swelling bath (water bath) at 20° C. for 30 seconds to swell and stretched 2.2 times in the conveying direction (swelling step). Next, the film was immersed in a dyeing bath at 30° C. (iodine aqueous solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the iodine concentration of the final polarizer to 3.1 wt % for 30 seconds, and stretched 3.3 times in the conveying direction relative to the original PVA film (PVA film not stretched at all in the conveying direction) (dyeing step). For stretching, rolls with different peripheral speed ratios were used. Next, the dyed PVA film was immersed in a crosslinking bath (aqueous solution containing 3.5 wt% boric acid, 3.0 wt% potassium iodide, and 3.6 wt% zinc sulfate) at 40°C for 28 seconds and stretched to 3.6 times the original PVA film in the conveying direction (crosslinking step). Next, the crosslinked PVA film was immersed in a stretching bath (aqueous solution containing 4.5 wt% boric acid, 5.0 wt% potassium iodide, and 5.0 wt% zinc sulfate) at 64°C for 60 seconds and stretched to 6.0 times the original PVA film in the conveying direction (stretching step). Next, the PVA film was immersed in a washing bath (aqueous solution containing 2.3 wt% potassium iodide) at 27°C for 10 seconds (washing step), and the washed PVA film was dried at 40°C for 30 seconds to obtain a polarizer A having a thickness of 18 μm.

[0219] (Preparation of Polarizer B) Using rolls with different peripheral speed ratios, an 80 μm thick PVA film was stretched 3.0 times in the conveyance direction while being dyed with an iodine aqueous solution (concentration 0.3 wt%) at 30° C. for 1 minute. Next, the film was immersed in an aqueous solution containing 4 wt% boric acid and 10 wt% potassium iodide at 60° C. for 0.5 minutes, and stretched 6.0 times in the conveyance direction based on the original PVA film. Next, the film was immersed in an aqueous solution containing 1.5 wt% potassium iodide at 30° C. for 10 seconds for washing, and then dried at 50° C. for 4 minutes to obtain a 28 μm thick polarizer B.

[0220] (Preparation of Polarizer C) A 60 μm thick PVA film was stretched 3.0 times in the conveyance direction using rolls with different peripheral speed ratios while dyeing with an iodine aqueous solution (concentration 0.3 wt%) at 30° C. for 1 minute. Next, the film was immersed in an aqueous solution containing 4 wt% boric acid and 10 wt% potassium iodide at 60° C. for 0.5 minutes, and stretched 6.0 times in the conveyance direction based on the original PVA film. Next, the film was immersed in an aqueous solution containing 1.5 wt% potassium iodide at 30° C. for 10 seconds for washing, and then dried at 50° C. for 4 minutes to obtain a 22 μm thick polarizer C.

[0221] (Preparation of Retardation Film A) In an autoclave equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer, 48 parts by weight of hydroxypropyl methylcellulose (Metolose 60SH-50, manufactured by Shin-Etsu Chemical Co., Ltd.), 15,601 parts by weight of distilled water, 8,161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of the polymerization initiator t-butyl peroxypivalate were placed, and after 1 hour of nitrogen bubbling, the mixture was stirred at 49 ° C. for 24 hours to allow radical suspension polymerization to proceed. Next, after cooling to room temperature, the fumarate ester resin particles produced by polymerization were centrifuged. The obtained particles were washed twice with distilled water and twice with methanol, and then dried under reduced pressure. Next, the particles were dissolved in a toluene-methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone 50 wt% / 50 wt%) to obtain a solution with a concentration of 20 wt%. Furthermore, 5 parts by weight of tributyl trimellitate as a plasticizer was added to 100 parts by weight of the fumaric acid ester resin to prepare a dope. The prepared dope was then applied to a support film so that the film thickness after drying was 6.3 μm, and dried at 140°C. A biaxially stretched polyester (polyethylene terephthalate / polyethylene isophthalate copolymer) film (thickness: 75 μm, heat-treated) was used as the support. The laminate thus obtained was then uniaxially stretched at 140°C. The support film was peeled off from the stretched laminate to obtain a retardation film A (thickness: 6 μm, Re(550): 35 nm).

[0222] (Preparation of Polarizing Film A) HC-attached protective film A was laminated to one main surface of polarizer A, and retardation film B (ZT12, a 17 μm-thick cycloolefin film manufactured by Zeon Corporation) was laminated to the other main surface using a roll laminator. Lamination was performed at 30°C using an adhesive. The adhesive used was an aqueous solution containing acetoacetyl-containing PVA (average degree of polymerization 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1. Next, the entire assembly was dried by heating in an oven, and then a photocurable adhesive composition was applied to the retardation film B side of the resulting laminated film to a thickness of 1 μm. An MCD coater (manufactured by Fuji Machinery Co., Ltd.) was used for the coating. The adhesive composition had the following composition: 20 parts by weight of unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone (manufactured by Daicel, Placcel FA1DDM); 20 parts by weight of acryloylmorpholine (manufactured by Kohjin); 3 parts by weight of diethylacrylamide (manufactured by KJ Chemicals, DEAA); 6.7 parts by weight of lauryl acrylate (manufactured by Kyoeisha Chemical, Light Acrylate L-A); 27 parts by weight of isostearyl acrylate (manufactured by Osaka Organic Chemical Industry, ISTA); 10 parts by weight of 1,9-nonanediol diacrylate (manufactured by Kyoeisha Chemical, Light Acrylate 1,9ND-A); 13.3 parts by weight of a 34 / 66 molar ratio copolymer oligomer of butyl acrylate and methacrylate (manufactured by Toagosei, ARUFON UP-1190, molecular weight 1700); and 13.3 parts by weight of Omnirad 907 (IGM Resins) as a photoinitiator. 3 parts by weight of diethylthioxanthone (manufactured by Nippon Kayaku, KAYACURE DETX-S) as a photoinitiator

[0223] Next, the retardation film A prepared above was laminated using a roll laminator so as to be in contact with the applied adhesive composition. The lamination was performed at 30°C. Next, visible light (irradiation device: Light HAMMER 10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak irradiance: 1600 mW / cm) was irradiated from the retardation film A side as active energy rays using a gallium-encapsulated metal halide lamp as a light source. 2 , cumulative irradiation dose of 1000 / mJ / cm at wavelengths of 380 to 440 nm2 ) to cure the adhesive composition. The film was then thermally dried at 70°C for 3 minutes to obtain polarized film A. The curl diameter of polarized film A measured by the above-mentioned method was 6.0 mm, and the bending moment M was 3.0 × 10 6 It was.

[0224] (Preparation of Polarizing Film B) HC-attached protective film A was attached to one main surface of polarizer A, and a transparent protective film (manufactured by Nippon Shokubai, thickness 30 μm) made of a modified acrylic polymer having a lactone ring structure was attached to the other main surface using a roll laminator. The lamination was carried out at 30°C using an adhesive. The adhesive used was an aqueous solution containing acetoacetyl group-containing PVA (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1. The entire film was then heated and dried in an oven to obtain polarizing film B. The curl diameter of polarizing film B measured using the above-mentioned method was 6.0 mm, and the bending moment M was 2.0 × 10 6 It was.

[0225] (Preparation of Polarizing Film C) A transparent protective film containing triacetyl cellulose (TAC film manufactured by Fujifilm, product name "TG40UL", thickness 40 μm) was laminated to one main surface of Polarizer A, and a transparent protective film made of a modified acrylic polymer having a lactone ring structure (manufactured by Nippon Shokubai, thickness 30 μm) was laminated to the other main surface using a roll laminator. The lamination was carried out at 30°C using an adhesive. The adhesive used was an aqueous solution containing acetoacetyl group-containing PVA (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1. The entire film was then heated and dried in an oven to obtain Polarizing Film C. The curl diameter of Polarizing Film C measured by the above-mentioned method was 3.0 mm, and the bending moment M was 3.5×10 6 It was.

[0226] (Preparation of Polarizing Film D) HC-attached protective film A was attached to one main surface of polarizer B, and a transparent protective film (manufactured by Nippon Shokubai, thickness 30 μm) made of a modified acrylic polymer having a lactone ring structure was attached to the other main surface using a roll laminator. The lamination was carried out at 30°C using an adhesive. The adhesive used was an aqueous solution containing acetoacetyl group-containing PVA (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1. The entire film was then heated and dried in an oven to obtain polarizing film D. The curl diameter of polarizing film D measured using the above-mentioned method was 7.8 mm, and the bending moment M was 3.0 × 10 6 It was.

[0227] (Preparation of Polarizing Film E) A transparent protective film containing triacetyl cellulose (TAC film manufactured by Fujifilm, product name "TG40UL", thickness 40 μm) was laminated to one main surface of Polarizer C, and a transparent protective film made of a modified acrylic polymer having a lactone ring structure (manufactured by Nippon Shokubai, thickness 20 μm) was laminated to the other main surface using a roll laminator. The lamination was carried out at 30°C using an adhesive. The adhesive used was an aqueous solution containing acetoacetyl group-containing PVA (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1. The entire film was then heated and dried in an oven to obtain Polarizing Film E. The curl diameter of Polarizing Film E measured by the above-mentioned method was 2.5 mm, and the bending moment M was 8.0 × 10 6 It was.

[0228] <Preparation of First Laminate L1> One of the coating solutions prepared above was applied to the exposed surface of the transparent protective film of each of the polarizing films prepared above, and the resulting coating was dried at a predetermined temperature for 1 minute to prepare first laminates L1-1 to L1-21 having a laminate structure of antistatic layer / polarizing film. Table 2 below shows the production conditions and thickness of the antistatic layer provided in each of the prepared first laminates L1.

[0229]

[0230] [Evaluation of Surface Resistivity of Antistatic Layer] For each of the prepared first laminates L1, the surface resistivity of the antistatic layer was evaluated before and after the DIN test. The DIN test was conducted in accordance with the weather resistance test (test conditions: Z-IN1) specified in DIN 75220. The surface resistivity was measured before and after the DIN test using a Hiresta MCP-HT800 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) under conditions of an applied voltage of 10 V and an application time of 10 seconds in accordance with the method specified in JIS K6911:1995. The surface resistivity was evaluated at 25°C. The evaluation results are shown in Table 3 below.

[0231]

[0232] [Preparation of Second Laminate L2 Composed of Substrate and Pressure-Sensitive Adhesive Sheet] <Preparation of (Meth)acrylic Polymer> A monomer mixture containing 67 parts by weight of 2-methoxyethyl acrylate (MEA), 22 parts by weight of n-butyl acrylate (BA), 10 parts by weight of phenoxyethyl acrylate (PEA), and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. Next, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) as a polymerization initiator was charged together with 100 parts by weight of ethyl acetate per 100 parts by weight of the monomer mixture. While gently stirring the mixture, nitrogen gas was introduced into the flask to replace the atmosphere with nitrogen. The liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was allowed to proceed for 8 hours, preparing a (meth)acrylic polymer solution with a weight-average molecular weight (Mw) of 2,000,000.

[0233] The weight average molecular weight (Mw) of the (meth)acrylic polymer was measured by GPC (gel permeation chromatography). The GPC measurement conditions are as follows: Analytical device: HLC-8120GPC, manufactured by Tosoh Corporation Column: G7000HXL + GMHXL + GMHXL, manufactured by Tosoh Corporation Column size: 7.8 mmφ x 30 cm each, 90 cm in total Column temperature: 40°C Flow rate: 0.8 mL / min Injection volume: 100 μL Eluent: tetrahydrofuran Detector: differential refractometer (RI) Standard sample: polystyrene

[0234] <Preparation of Pressure-Sensitive Adhesive Sheet and Second Laminate L2> 0.3 parts by weight of a crosslinker (manufactured by Tosoh Corporation, trade name: Coronate 2770), 8 parts by weight of an antistatic agent, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI); (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Elexel AS110), and 0.5 parts by weight of an antioxidant (manufactured by BASF, trade name: Irganox 1010), were further blended relative to 100 parts by weight of the solids content of the (meth)acrylic polymer solution prepared above to prepare a solution of a (meth)acrylic pressure-sensitive adhesive composition. Next, the prepared solution was applied to one side of a release film (manufactured by Mitsubishi Chemical Polyester Film Corporation, MRF38). The release film used was a polyethylene terephthalate film surface-treated with a silicone-based release agent. The coating film formed by application was dried at 155°C for 1 minute to obtain a second laminate L2-1 in which a pressure-sensitive adhesive sheet was formed on the surface of the release film. The thickness of the formed PSA sheet was 20 μm. Furthermore, a second laminate L2-2 was obtained in the same manner as above, except that the blending amount of the antistatic agent was 6 parts by weight. The surface resistivity of the PSA sheet was evaluated for each of the prepared second laminates L2, and the laminate L2-1 had a surface resistivity of 2.0 × 10 8 Ω / □, 2.0 × 10 for laminate L2-2 9 The surface resistivity of the pressure-sensitive adhesive sheet was measured in the same manner as the surface resistivity of the antistatic layer (applied voltage 10 V, application time 10 seconds, environmental temperature 25° C.). The surface resistivity of the pressure-sensitive adhesive sheet hardly changed before and after the DIN test.

[0235] [Preparation of Optical Laminate] The pressure-sensitive adhesive sheet of each of the second laminates L2 prepared above was bonded to the antistatic layer of each of the first laminates L1 to obtain an optical laminate in which a polarizing film, an antistatic layer, a pressure-sensitive adhesive sheet, and a release film were laminated in this order. Optical laminates prepared using each of the first laminates L1-1 to L1-15 and L1-19 to L1-21 were designated Examples 1 to 15 and Examples 16 to 18, respectively. Optical laminates prepared using each of the first laminates L1-16 to L1-18 were designated Comparative Examples 1 to 3, respectively. The following evaluations were performed on each of the optical laminates of Examples 1 to 18 and Comparative Examples 1 to 3 before and after the DIN test. Furthermore, the curl and loss of total light transmittance due to the antistatic layer were evaluated for each of the prepared optical laminates (before the DIN test). The loss of total light transmittance was measured using the method described above.

[0236] (Curling) The degree of curling of the produced optical laminate was evaluated by visual observation. The evaluation criteria are as follows: A: Curling is suppressed and good; B: Slight curling occurs, but no problem in use; C: Curling is observed, but no problem in use; D: Severe curling occurs, and there is a possibility of problems in use.

[0237] (ESD Test) After peeling the release film from the optical laminate to be evaluated, the optical laminate was attached to the viewing side of an in-cell image display panel (liquid crystal panel) having the configuration shown in FIG. 7 via the adhesive sheet provided with the optical laminate. Next, a 10 mm wide silver paste was applied to the side of the polarizing film and connected to an external earth electrode. The silver paste was applied so as to cover the side of the polarizing film, the antistatic layer, and the adhesive sheet. Next, the image display panel was placed on a backlight device, and an electrostatic discharge gun was fired at the polarizing film surface on the viewing side at an applied voltage of 9 kV to check whether any abnormalities occurred in the display function. The evaluation criteria were as follows: A: No abnormalities were observed on the screen, and the display function was normal. B: Abnormalities such as horizontal lines and flickering occurred on the screen, but the display function automatically recovered. C: Abnormalities such as horizontal lines and flickering occurred on the screen, and the display function did not recover.

[0238] (TSP test) After peeling off the release film from the optical laminate to be evaluated, the optical laminate was attached to the viewing side of an in-cell image display panel (liquid crystal panel) having the configuration shown in Figure 7 via an adhesive sheet provided with the optical laminate. Next, the wiring around the transparent electrode pattern of the image display device to which the optical laminate was attached was connected to a controller IC to produce an image display device with a built-in touch sensing function. The input display of the device using the touch sensor was visually observed to confirm the presence or absence of malfunction. A: No malfunction D: Malfunction occurred

[0239] (Surface Resistivity C, D) The surface resistivity C (before DIN test) and surface resistivity D (after DIN test) of the main surface 5 of the pressure-sensitive adhesive sheet 1 in the optical laminate were measured by the method described above. The surface resistivities C and D were measured using a Hiresta MCP-HT800 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a J-Box U-type (MCP-JB03) probe in accordance with the method defined in JIS K6911:1995, at an applied voltage of 500 V, an application time of 30 seconds, and an ambient temperature of 25°C.

[0240] The evaluation results are shown in Table 4 below.

[0241]

[0242] As shown in Table 4, the electrical properties of the optical laminates of the Examples after exposure to the DIN test environment were more suitable for use as an image display device than those of the optical laminates of the Comparative Examples. Among the Examples, the absolute value of the log B - log A value exceeded 1 in Example 1, in which the drying temperature during formation of the antistatic layer was 70°C, Examples 6 and 7, in which the solvent for the coating liquid for the antistatic layer was 100% IPA or a mixed solvent of IPA and water, and Examples 10 and 11, in which a leveling agent was added to the coating liquid for the antistatic layer. Furthermore, the absolute value of the change in total light transmittance was 0.27% or more in Example 1, in which the drying temperature during formation of the antistatic layer was 70°C, and Examples 6 and 7, in which the solvent for the coating liquid for the antistatic layer was 100% IPA or a mixed solvent of IPA and water.

[0243] As shown in Table 4, when the drying temperature during the formation of the antistatic layer was 130° C. or higher (Examples 4 and 5), and the smaller the curl diameter of the polarizing film used, the greater the degree of curl.

[0244] The optical laminate of the present invention is suitable for application to image display devices used in environments where static electricity is likely to be generated due to the presence of other electronic devices around, such as the inside of a vehicle, and where high temperatures and humidity are likely to occur.

Claims

1. An optical laminate comprising an adhesive sheet, an antistatic layer, and an optical film, wherein the antistatic layer satisfies the following formula (1), where A and B in the formula (1) are the surface resistivities (unit: Ω / □) of the antistatic layer before and after a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220, respectively. -2≦log B-log A≦2 (1) 2. The surface resistivity B of the antistatic layer is 1.0×10 6 Ω / □ or more 3.0×10 8 The optical laminate according to claim 1, having a resistance to vibration of Ω / □ or less.

3. The optical laminate according to claim 1, wherein the antistatic layer has a thickness of 5 nm or more and 100 nm or less.

4. The optical stack according to claim 1, wherein the antistatic layer comprises carbon nanotubes.

5. The optical laminate according to claim 4, wherein the carbon nanotubes have a length of 3 μm or more and 300 μm or less, and a diameter of 10 nm or less.

6. The optical laminate according to claim 1, wherein the antistatic layer contains a binder resin.

7. The optical laminate according to claim 1, wherein the antistatic layer contains a binder resin having a glass transition temperature of 0° C. or higher.

8. The optical laminate according to claim 1, wherein the antistatic layer is substantially free of a leveling agent.

9. The optical laminate according to claim 1, wherein the pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive composition containing a polymer (A).

10. The optical laminate according to claim 9, wherein the polymer (A) is a (meth)acrylic polymer.

11. The optical laminate according to claim 9, wherein the pressure-sensitive adhesive composition contains the polymer (A) having a polyether structure as a main component.

12. The optical laminate according to claim 11, wherein the polymer (A) has a structural unit derived from a monomer represented by the following formula (2). R in formula (2) 1 is a hydrogen atom or a methyl group, R 2 is an alkyl group which may be linear or branched, and n is an integer of 1 to 15.

13. The optical laminate according to claim 9, wherein the pressure-sensitive adhesive composition further comprises an antistatic agent.

14. The optical laminate according to claim 13, wherein the pressure-sensitive adhesive composition contains less than 30 parts by weight of the antistatic agent per 100 parts by weight of the polymer (A).

15. The optical laminate according to claim 1, wherein the loss in total light transmittance due to the antistatic layer is 1.0% or less.

16. The optical laminate of claim 1, wherein the optical film comprises a polarizing film.

17. The optical laminate according to claim 16, wherein the curl diameter of the polarizing film evaluated by the following test method is 3 mm or more. <Test method> The polarizing film is processed into a rectangle of 10 mm width x 50 mm length with the absorption axis of the polarizer in the longitudinal direction to prepare a test piece. Next, one end of the test piece in the longitudinal direction is fixed to the surface of an evaluation sheet. Next, the entirety is heated at 105°C for 12 hours to curl the test piece from the other end of the test piece in the longitudinal direction. The diameter of the cylindrical portion of the test piece formed by curling is obtained as the curl diameter.

18. The absolute value of the bending moment M of the polarizing film when heated is 1×10 9 The optical laminate according to claim 16, wherein the optical laminate is less than 100%.

19. The optical laminate according to claim 1, wherein the antistatic layer contains carbon nanotubes and a binder resin having a glass transition temperature of 0° C. or higher.

20. The optical laminate according to claim 19, wherein the carbon nanotubes have a length of 3 μm or more and 300 μm or less, and a diameter of 10 nm or less.

21. The optical laminate according to claim 1, comprising, in this order, the pressure-sensitive adhesive sheet, the antistatic layer, and the optical film, and satisfying the following formula (4): -1≦log D-log C≦2 (4) where C in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate, and D in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the pressure-sensitive adhesive sheet opposite the antistatic layer in the optical laminate that has undergone the weather resistance test.

22. An optical laminate comprising, in this order, an adhesive sheet, an antistatic layer, and an optical film, and satisfying the following formula (4): -1≦log D-log C≦2 (4) where C in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the adhesive sheet opposite the antistatic layer in the optical laminate, and D in formula (4) is the surface resistivity (unit: Ω / □) of the main surface of the adhesive sheet opposite the antistatic layer in the optical laminate that has undergone a weather resistance test (test condition: Z-IN1) specified in German Industrial Standard DIN 75220.

23. An image display panel comprising the optical laminate according to any one of claims 1 to 22.

24. An image display device comprising the image display panel according to claim 23.

Images