Optical adhesive sheet

Abstract

To provide an optical adhesive sheet that can suppress the generation of static electricity when peeling an adhesive sheet from an image display panel for rework purposes. Furthermore, to provide an optical adhesive sheet that can suppress the gradual deterioration of the visibility of an image display device due to thermal shock. [Solution] The optical adhesive sheet 10A has a laminated structure in which a base material 1 having a first surface 1a and a second surface 1b is laminated on the first surface 1a of the base material 1. The adhesive layer 2 contains a liquid antistatic agent. The surface resistance of the adhesive layer 2 is 10 10 It is less than Ω. The haze of the optical adhesive sheet 10A after the thermal shock test described below is 1% or less. • Thermal shock test The optical adhesive sheet 10A is subjected to thermal shock using a thermal shock tester for 200 cycles, consisting of one cycle of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes.

Description

[Technical Field]

[0001] This invention relates to an optical adhesive sheet. More specifically, it relates to an optical adhesive sheet suitable for the manufacture of an image display device. [Background technology]

[0002] Liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) are widely used as various image display devices, such as smartphones, computer monitors, and televisions. In these image display devices, a transparent front panel, such as a transparent resin plate or glass plate, is provided on the viewing side of the image display panel to prevent damage to the panel from external impacts. Furthermore, image display devices equipped with a touch panel on the viewing side of the image display panel are also becoming common.

[0003] As a method for arranging the aforementioned front transparent plate, touch panel, etc., on the front of the image display panel, a "layer-filled structure" has been proposed in which the image display panel and the front transparent plate, touch panel, etc., are bonded together via an adhesive sheet (for example, Patent Document 1). In some cases, an adhesive sheet is also provided between the front transparent plate and the touch panel. In the layer-filled structure, since the gaps between the components are filled with adhesive, the refractive index difference at the interface is reduced, and the decrease in visibility caused by reflection and scattering is suppressed. In addition, in the layer-filled structure, since the components are bonded together and fixed by the adhesive sheet, there is an advantage that the components are less likely to peel off due to impacts such as dropping compared to when the components are fixed only to the housing.

[0004] When attaching an image display panel with an adhesive sheet, adhesion defects such as air bubbles or misalignment may occur. If adhesion defects occur, it is desirable to peel off the adhesive sheet from the image display panel and reuse the image display panel (this may be referred to as "rework" in this specification). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-125524 [Overview of the project] [Problems that the invention aims to solve]

[0006] When a bonding defect occurs, static electricity is generated on the adhesive sheet when peeling it off the image display panel in order to rework the panel. This generated static electricity affects the orientation of the display cells in the image display panel, causing display defects. In particular, in image display panels with a high pixel count for higher image quality, it is difficult to provide separate ground wiring to dissipate static electricity, and measures to discharge static electricity are necessary.

[0007] Furthermore, repeated switching the power of the image display device on and off caused thermal shock (periodic heating and cooling), which resulted in gaps forming at the interface between the adhesive sheet and the image display panel, and increased haze on the adhesive sheet, leading to a decrease in the visibility of the image display device over time.

[0008] The present invention was conceived under the circumstances described above, and its objective is to provide an optical adhesive sheet that can suppress the generation of static electricity when peeling an adhesive sheet from an image display panel for reworking the image display panel. Another objective of the present invention is to provide an optical adhesive sheet that can suppress the gradual deterioration of the visibility of an image display device due to thermal shock.

[0009] Furthermore, a transparent, conductive printed layer, such as patterned ITO (indium tin oxide), is formed on the surface of the touch panel, and silver or copper wiring is formed around the periphery. In addition, it is common to print a black, frame-like concealing area around the edge of the front transparent plate. When there are uneven surfaces such as raised or recessed areas in the printed layers or wiring of various components such as the image display panel, front transparent plate, and touch panel, the adhesive sheet used to join them is required to exhibit the characteristic (sometimes referred to as "step absorption" in this specification) of the adhesive layer adequately following these steps and filling them without leaving air bubbles. [Means for solving the problem]

[0010] In other words, the first aspect of the present invention provides an optical adhesive sheet having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer laminated on the first surface of the substrate. In this specification, the optical adhesive sheet of the first aspect of the present invention may be referred to as "the optical adhesive sheet of the present invention." Furthermore, the adhesive layer constituting the optical adhesive sheet of the present invention may be referred to as "the adhesive layer of the present invention," and the substrate may be referred to as "the substrate of the present invention."

[0011] The optical adhesive sheet of the present invention can be suitably used in the manufacture of image display devices. Specifically, the adhesive layer of the present invention can be suitably used to bond a front transparent plate, a touch panel, and other optical components (such as polarizing films and phase difference films) to an image display panel constituting an image display device. Furthermore, the substrate of the present invention can be various optical components used in the manufacture of image display devices, such as a front transparent plate, a touch panel, and other optical components (such as polarizing films and phase difference films).

[0012] In the optical adhesive sheet of the present invention, the adhesive layer of the present invention contains a liquid antistatic agent. The antistatic agent imparts antistatic properties to the adhesive layer of the present invention and is preferable in that it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel. Furthermore, the configuration in which the antistatic agent is liquid is preferable in that it can impart an excellent antistatic effect to the adhesive layer of the present invention without impairing the adhesive properties of the adhesive layer of the present invention, thereby improving the adhesion between the adhesive layer of the present invention and the substrate of the present invention. For example, even under harsh environments such as thermal shock (periodically repeating heating and cooling), it is preferable in that it prevents voids from forming at the interface between the adhesive layer and the substrate of the present invention and reduces transparency, thereby maintaining excellent optical properties (in this specification, such properties may be referred to as "thermal shock resistance").

[0013] In the optical adhesive sheet of the present invention, the surface resistance value of the adhesive layer of the present invention is 10 10 It is less than Ω. The surface resistance of the adhesive layer of the present invention is 10 10 The configuration having a resistance of less than Ω is preferable because the adhesive layer of the present invention exhibits excellent antistatic effect, and it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel.

[0014] The haze of the optical adhesive sheet of the present invention after the following thermal shock test is 1% or less. • Thermal shock test The optical adhesive sheet of the present invention is subjected to thermal shock for 200 cycles using a thermal shock tester, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes.

[0015] The configuration of the optical adhesive sheet of the present invention, in which the haze after the above thermal shock test is 1% or less, is preferable because it allows the image display device of the present invention to maintain excellent visibility even in harsh environments such as thermal shock.

[0016] In the optical adhesive sheet of the present invention, the antistatic agent is preferably an ionic liquid. The configuration in which the antistatic agent is an ionic liquid is preferable because it can impart an excellent antistatic effect to the adhesive layer of the present invention without impairing the adhesive properties of the adhesive layer of the present invention, thereby improving the adhesion between the adhesive layer of the present invention and the substrate of the present invention, and obtaining excellent thermal shock resistance.

[0017] In the optical adhesive sheet of the present invention, the ionic liquid preferably contains an anionic component having 10 or fewer fluorine atoms. The configuration in which the ionic liquid contains an anionic component having 10 or fewer fluorine atoms is preferable because it improves the compatibility of the ionic liquid with the adhesive layer of the present invention, suppresses the increase in haze due to the separation of the ionic liquid from the adhesive layer, and improves the visibility of the image display device.

[0018] The difference in haze of the optical adhesive sheet of the present invention before and after the thermal shock test (haze of the optical adhesive sheet after the thermal shock test - haze of the optical adhesive sheet before the thermal shock test) is preferably 2% or less. The configuration in which the difference in haze of the optical adhesive sheet of the present invention before and after the thermal shock test is 2% or less is preferable because it allows the image display device of the present invention to maintain excellent visibility even in harsh environments such as thermal shock.

[0019] Preferably, the absolute value of the difference in surface resistance of the adhesive layer of the present invention before and after the above thermal shock test, as shown by the following formula, is 1 log Ω or less. |Log 10 B-Log 10 A| A: Surface resistance value before thermal shock test B: Surface resistance value after thermal shock test

[0020] The configuration in which the difference in surface resistance of the adhesive layer of the present invention before and after the thermal shock test described above is 1 log Ω or less is preferable because it allows the adhesive layer of the present invention to maintain excellent antistatic effect even in harsh environments such as thermal shock, and for example, when a malfunction such as failure of a light-emitting element occurs in the operating environment of an image display device, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel in order to repair it.

[0021] In the optical adhesive sheet of the present invention, it is preferable that the second surface of the substrate is treated with an anti-reflective coating and / or an anti-glare coating. The configuration in which the second surface of the substrate is treated with an anti-reflective coating and / or an anti-glare coating is preferable because it can prevent reflections caused by metal wiring, ITO wiring, etc., arranged on the substrate of the image display device, and improve visibility.

[0022] In the optical adhesive sheet of the present invention, the adhesive layer is preferably an acrylic adhesive layer containing an acrylic polymer. This configuration is suitable for adjusting the above-mentioned properties of the adhesive layer (particularly the step absorption properties).

[0023] Furthermore, a second aspect of the present invention provides an image display device in which the optical adhesive sheet of the present invention and an image display panel are laminated. In this specification, the image display device of the second aspect of the present invention may be referred to as the "image display device of the present invention." The image display device of the present invention is advantageous because, having the optical adhesive sheet of the present invention in a laminated structure, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel. Furthermore, it is advantageous because it can prevent the formation of gaps at the interface between the adhesive sheet and the image display panel due to thermal shock, or the increase in haze of the adhesive sheet, which would otherwise reduce the visibility of the image display device over time.

[0024] Furthermore, a third aspect of the present invention provides a tiling display in which multiple image display devices of the present invention are arranged side by side. In this specification, the tiling display of the third aspect of the present invention may be referred to as "the tiling display of the present invention." The tiling display of the present invention is suitable as a large-screen image display device for signage such as advertising displays and bulletin boards. [Effects of the Invention]

[0025] The optical adhesive sheet of the present invention is preferable because, when used in the manufacture of an image display device, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of adhesion defects to the image display panel. Furthermore, it is preferable because, without impairing the adhesive properties of the adhesive layer of the invention, it can impart an excellent antistatic effect to the adhesive layer of the invention, thereby improving the adhesion between the adhesive layer of the invention and the substrate of the invention, resulting in excellent thermal shock resistance, and preventing the formation of voids at the interface between the adhesive sheet and the image display panel, or the increase in haze of the adhesive sheet, which would otherwise reduce the visibility of the image display device over time. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a schematic diagram (cross-sectional view) showing one embodiment of the optical adhesive sheet of the present invention. [Figure 2] Figure 2 is a schematic diagram (cross-sectional view) showing another embodiment of the optical adhesive sheet of the present invention. [Figure 3] Figure 3 is a schematic diagram (cross-sectional view) showing one embodiment of the image display device of the present invention in which the optical adhesive sheets of Figure 2 are laminated. [Figure 4] Figure 4 is a schematic diagram (perspective view) showing one embodiment of the tiling display of the present invention. [Modes for carrying out the invention]

[0027] The optical adhesive sheet of the present invention has a laminated structure comprising a substrate having a first surface and a second surface, and an adhesive layer laminated on the first surface of the substrate. The term "adhesive sheet" includes the meaning of "adhesive tape." That is, the optical adhesive sheet of the present invention may be an adhesive sheet in the form of a tape.

[0028] The image display device of the present invention is an image display device in which an optical adhesive sheet of the present invention and an image display panel are laminated together. Furthermore, the tiling display of the present invention is a tiling display in which multiple image display devices of the present invention are arranged side by side.

[0029] The embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto and is merely illustrative.

[0030] Figure 1 is a schematic diagram (cross-sectional view) showing one embodiment of the optical adhesive sheet of the present invention. In Figure 1, the optical adhesive sheet 10A has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated together. The base material 1 has a first surface 1a and a second surface 1b, and the adhesive layer 2 is laminated on the first surface 1a of the base material 1.

[0031] In Figure 2, the optical adhesive sheet 10B has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated. The base material 1 has a first surface 1a and a second surface 1b, and the adhesive layer 2 is laminated on the first surface 1a of the base material 1. The second surface 1b of the base material 1 is treated with an anti-reflective coating and / or an anti-glare coating 3.

[0032] Figure 3 is a schematic diagram (cross-sectional view) showing one embodiment of the image display device of the present invention. In Figure 3, the image display device 20 has an image display panel 4 laminated in the adhesive layer 2 of the optical adhesive sheet 10B.

[0033] Figure 4 is a schematic diagram (perspective view) showing one embodiment of the tiling display of the present invention. In Figure 4, the tiling display 30 is formed by arranging nine image display devices 20 (the stacked structure is not shown) in a 3x3 array on a support substrate 31 in a tile-like manner. The following describes each component.

[0034] <Optical adhesive sheet> In the optical adhesive sheet of the present invention, "optical" means used for optical applications, and more specifically, it means used in the manufacture of products using optical components (optical products). Examples of optical products include image display devices and input devices such as touch panels, but it can be suitably used in the manufacture of liquid crystal image display devices, self-emissive image display devices (e.g., organic EL (electroluminescent) image display devices, LED image display devices), etc. In particular, the optical adhesive sheet of the present invention is suitable for the manufacture of self-emissive image display devices.

[0035] The optical adhesive sheet of the present invention is not particularly limited in form, as long as the adhesive layer of the present invention is laminated on the first surface of the substrate of the present invention. For example, it may be a single-sided adhesive sheet with adhesive on only one side, or a double-sided adhesive sheet with adhesive on both sides. Furthermore, if the optical adhesive sheet of the present invention is a double-sided adhesive sheet, it may have a form in which both adhesive surfaces are provided by the adhesive layer of the present invention, or one adhesive surface may be provided by the adhesive layer of the present invention and the other adhesive surface may be provided by an adhesive layer other than the adhesive layer of the present invention (another adhesive layer). A single-sided adhesive sheet is preferred when the optical adhesive sheet of the present invention constitutes the outermost surface of an optical product, and a double-sided adhesive sheet is preferred when bonding adherends (optical members) together.

[0036] The optical adhesive sheet of the present invention may have other layers, such as a substrate other than the substrate of the present invention, an adhesive layer other than the adhesive layer of the present invention, an intermediate layer, a primer layer, an antistatic layer, a release liner, a surface protective film, etc., on the surface or between any of the layers, to the extent that the effects of the present invention are not impaired.

[0037] The haze of the optical adhesive sheet of the present invention is not particularly limited, but is preferably 1% or less. The configuration in which the optical adhesive sheet of the present invention has a haze of 1% or less is preferable in that the image display device of the present invention exhibits excellent visibility. In terms of exhibiting even better visibility in the image display device of the present invention, the haze of the optical adhesive sheet of the present invention is preferably 0.8% or less, more preferably 0.5% or less, or may be 0.4% or less. The lower limit of the haze of the optical adhesive sheet of the present invention is not particularly limited, and is preferable as it is lower, but may be 0.01% or more.

[0038] The haze of the optical adhesive sheet of the present invention after the following thermal shock test is 1% or less. • Thermal shock test The optical adhesive sheet of the present invention is subjected to thermal shock for 200 cycles using a thermal shock tester, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes.

[0039] The configuration in which the optical adhesive sheet of the present invention has a haze of 1% or less after the above thermal shock test is preferable in that the image display device of the present invention can maintain excellent visibility even in harsh environments such as thermal shock. In terms of maintaining excellent visibility, the haze of the optical adhesive sheet of the present invention after the above thermal shock test is preferably 0.8% or less, more preferably 0.5% or less, or may be 0.4% or less. There is no particular limit to the lower limit of the haze of the optical adhesive sheet of the present invention after the above thermal shock test; the lower the better, but it may be 0.01% or more.

[0040] The difference in haze of the optical adhesive sheet of the present invention before and after the thermal shock test (haze of the optical adhesive sheet after the thermal shock test - haze of the optical adhesive sheet before the thermal shock test) is preferably 2% or less. The configuration in which the difference in haze of the optical adhesive sheet of the present invention before and after the thermal shock test is 2% or less is preferable in that the image display device of the present invention can maintain excellent visibility even in harsh environments such as thermal shock. In terms of maintaining excellent visibility, the difference in haze of the optical adhesive sheet of the present invention before and after the thermal shock test is more preferably 1.8% or less, even more preferably 1.5% or less, or may be 1 or less.

[0041] The haze of the optical adhesive sheet of the present invention, the haze of the optical adhesive sheet of the present invention after the above thermal shock test, and the difference therefrom can be measured in accordance with JIS K 7136, and specifically, they can be measured by the method described in the examples below. The haze of the optical adhesive sheet of the present invention, the haze of the optical adhesive sheet of the present invention after the above thermal shock test, and the difference therefrom can be adjusted by the type and thickness of the resin and glass constituting the base material of the present invention, the type and thickness of the resin constituting the adhesive layer of the present invention, the type and amount of the antistatic agent, and by applying an anti-reflective treatment and / or anti-glare treatment to the surface of the base material.

[0042] The visible light transmittance of the optical adhesive sheet of the present invention is not particularly limited, but is preferably 90% or higher. The configuration in which the visible light transmittance of the optical adhesive sheet of the present invention is 90% or higher is preferred in that it provides excellent visibility in the image display device of the present invention, and is more preferably 90.5% or higher, and may be 91% or higher. The upper limit of the visible light transmittance of the optical adhesive sheet of the present invention is not particularly limited, but may be 95% or lower.

[0043] The visible light transmittance of the optical adhesive sheet of the present invention can be measured in accordance with JIS K7361-1. The visible light transmittance of the optical adhesive sheet of the present invention can be adjusted by the type and thickness of the resin and glass constituting the base material of the present invention, the type and thickness of the resin constituting the adhesive layer of the present invention, the type and amount of the antistatic agent, applying an antireflection treatment and / or an antiglare treatment to the surface of the base material, and the like.

[0044] The L of the optical adhesive sheet of the present invention * a * b * L defined in the color system * is not particularly limited, but in terms of obtaining excellent visibility in the image display device of the present invention, 90 or more is preferable, 92 or more is preferable, 94 or more is preferable. Also, a * and b * are not particularly limited, and may be the same or different, and are preferably -5 to 5, more preferably -3 to 3, and particularly preferably in the range of -1 to 1 (especially 0 or almost 0).

[0045] Regarding the L * a * b * in the color system before and after the above heat shock test of the optical adhesive sheet of the present invention * The amount of change (Δb * ) of b is not particularly limited, but in terms of the optical adhesive sheet of the present invention showing excellent heat shock resistance, 0.1 or less is preferable, and 0.05 or less is preferable.

[0046] L * a * b * The color system means the color space called the International Commission on Illumination (CIE) 1976 color system, and can be measured in accordance with JIS Z 8781-4 (2013). L * a * b * L defined in the color system * a * b * and Δb *This can be adjusted by the type and thickness of the resin and glass constituting the base material of the present invention, the type and thickness of the resin constituting the adhesive layer of the present invention, the type and amount of the antistatic agent, and by applying an anti-reflective treatment and / or anti-glare treatment to the surface of the base material.

[0047] The adhesive strength of the optical adhesive sheet of the present invention when peeled from an acrylic plate at a peeling speed of 300 mm / min at 23°C and a peeling angle of 180° is not particularly limited, but from the viewpoint of sufficient adhesion between the substrate and the image display panel of the present invention, it is preferably 3N / 25mm or more, more preferably 5N / 25mm or more, and even more preferably 7N / 25mm or more. The optical adhesive sheet of the present invention is preferable when the adhesive strength of peeled from an acrylic plate at a peeling speed of 300 mm / min at 23°C and a peeling angle of 180° is 3N / 25mm, as this makes it easier to obtain good adhesion to the substrate and good suppression of lifting at steps. The upper limit of the adhesive strength of the optical adhesive sheet of the present invention when peeled from an acrylic plate at a peeling speed of 300 mm / min at 23°C and a peeling angle of 180° is not particularly limited, but for example it is 40N / 20mm, and more preferably 60N / 20mm.

[0048] The amount of static electricity generated when peeling the optical adhesive sheet of the present invention from an acrylic plate at a peeling speed of 5 mm / min at 23°C and a peeling angle of 150° is not particularly limited, but is preferably within ±2kV, more preferably within ±1.5kV, and even more preferably within ±1kV, in order to suppress the generation of static electricity when peeling the adhesive sheet from the image display panel in order to rework in the event of poor adhesion to the image display panel.

[0049] The adhesive strength of the optical adhesive sheet of the present invention when peeled from an acrylic plate at a peeling speed of 300 mm / min at 23°C and a peeling angle of 180°, and the amount of peel charge when peeled from an acrylic plate at a peeling speed of 5 mm / min at 23°C and a peeling angle of 150°, are measured by the adhesive strength and peel charge measurements in the examples described below. The adhesive strength of the adhesive layer of the present invention when peeled from an acrylic plate at a peeling speed of 300 mm / min at 23°C and a peeling angle of 180°, and the amount of peel charge when peeled from an acrylic plate at a peeling speed of 5 mm / min at 23°C and a peeling angle of 150°, can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0050] The thickness of the optical adhesive sheet of the present invention is not particularly limited, but considering, for example, dimensional stability, strength, workability such as handling, and thinness, it is preferably in the range of 10 to 500 μm, more preferably in the range of 20 to 300 μm, and optimally in the range of 30 to 200 μm.

[0051] <Base material> Examples of materials constituting the base material of the present invention include glass and plastic films. Examples of the plastic film include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP) (e.g., trade name "Arton" (manufactured by JSR Corporation), trade name "Zeonor" (manufactured by Nippon Zeon Co., Ltd.), etc.), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), triacetylcellulose (TAC), polysulfone, polyarylate, polyether ether ketone (PEEK), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer. Polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI) are preferred because they have excellent dimensional stability and are less prone to shrinkage. These plastic materials can be used individually or in combination of two or more. The base material of the present invention is the portion that is attached to the substrate (such as an image display panel) together with the adhesive layer when the optical adhesive sheet of the present invention is attached to the substrate. The release liner that is peeled off when the optical adhesive sheet of the present invention is used (attached) is not included in the "base material".

[0052] The substrate of the present invention has a film-like (substrate-like) form having a first surface and a second surface. The substrate of the present invention is not particularly limited as long as it is a component of the image display device of the present invention, and examples include a front transparent plate, a touch panel, and various optical films such as other optical components (polarizing film, phase difference film, etc.), and is preferably used as a front transparent plate. When the substrate of the present invention is a front transparent plate, the second surface becomes the outermost surface of the image display device of the present invention.

[0053] The glass transition temperature (Tg) of the substrate of the present invention is not particularly limited, but is preferably 60°C or higher. The configuration in which the glass transition temperature of the substrate of the present invention is 60°C or higher is preferable in that the mechanical properties of the image display device of the present invention are stable under the usage environment. From the viewpoint of the stability of the mechanical properties of the image display device of the present invention, the glass transition temperature of the substrate may be 63°C or higher, or 65°C or higher. Furthermore, although the upper limit of the glass transition temperature of the substrate is not particularly limited, in that the molding process of the substrate can be simplified, the glass transition temperature of the substrate is preferably 350°C or lower, and may be 250°C or lower, 200°C or lower, 140°C or lower, 130°C or lower, or 125°C or lower.

[0054] The glass transition temperature (Tg) of the substrate of the present invention can be measured in accordance with JIS K 7121. The glass transition temperature (Tg) of the substrate of the present invention can be adjusted by the type of resin constituting the substrate of the present invention.

[0055] The moisture expansion coefficient of the substrate of the present invention is not particularly limited, but is 5 × 10 -5 It is preferable that the humidity expansion coefficient of the substrate of the present invention is 5 × 10⁻⁶. -5 A configuration of less than / %RH is preferable in that it improves the dimensional stability of the substrate of the present invention with respect to humidity changes, suppresses shrinkage or expansion of the image display device of the present invention under the usage environment, and maintains transparency without change. In terms of dimensional stability of the substrate of the present invention, minimal shrinkage or expansion, and maintenance of transparency without change, the humidity expansion coefficient of the substrate of the present invention is 3 × 10⁻⁶. -5 Preferably less than / %RH, 2 × 10 -5 It may be less than or equal to / %RH. The lower limit of the moisture expansion coefficient of the substrate of the present invention is not particularly limited, and a lower value is preferable, but is 0.001 × 10 -5 / %RH or higher is also acceptable. The moisture expansion coefficient of the substrate of the present invention can be adjusted depending on the type of resin constituting the substrate and the conditions during substrate manufacturing (temperature, extrusion speed, etc.).

[0056] The haze of the substrate of the present invention is not particularly limited, but is more preferably 1% or less, more preferably 0.8% or less, even more preferably 0.5% or less, or may be 0.4% or less, in terms of the excellent visibility of the image display device of the present invention. The lower limit of the haze of the substrate of the present invention is not particularly limited, and is preferable as low as possible, but may be 0.01% or more.

[0057] The haze of the substrate of the present invention can be measured in accordance with JIS K 7136. The haze of the substrate of the present invention can be adjusted by the type and thickness of the resin constituting the substrate of the present invention, and by applying an anti-reflective treatment and / or anti-glare treatment to the surface of the substrate.

[0058] The reflectivity of the substrate of the present invention is not particularly limited, but is preferably 5% or less. The configuration in which the reflectivity of the substrate of the present invention is 5% or less is preferable in that it can prevent reflections caused by metal wiring, ITO wiring, etc., arranged on the substrate of the image display panel in the image display device of the present invention, and is more preferably 3% or less, and may be 1.5% or less. The lower limit of the reflectivity of the substrate of the present invention is not particularly limited, but may be 0.1% or more, or 0.3% or more.

[0059] The reflectance of the substrate of the present invention can be measured in accordance with JIS K7361-1. The reflectance of the substrate of the present invention can be adjusted by the type and thickness of the resin constituting the substrate of the present invention, and by applying an anti-reflective treatment and / or anti-glare treatment to the surface of the substrate.

[0060] The thickness of the substrate of the present invention is not particularly limited, but considering, for example, dimensional stability, strength, workability such as handling, and thinness, it is preferably in the range of 10 to 500 μm, more preferably in the range of 20 to 300 μm, and optimally in the range of 30 to 200 μm. The refractive index of the substrate of the present invention is not particularly limited, but for example, it is in the range of 1.30 to 1.80, and preferably in the range of 1.40 to 1.70.

[0061] The second surface of the substrate of the present invention is preferably subjected to a reflective surface treatment and / or anti-glare treatment. The configuration in which the second surface of the substrate of the present invention is subjected to a reflective surface treatment and / or anti-glare treatment is preferable because it can prevent reflections caused by metal wiring, ITO wiring, etc., arranged on the substrate of the image display device of the present invention.

[0062] The aforementioned anti-reflective treatment can be any known anti-reflective treatment without any particular limitations, such as anti-reflection (AR) treatment.

[0063] The aforementioned anti-reflection (AR) treatment can be any known AR treatment without particular limitation. Specifically, it can be carried out by forming an anti-reflective layer (AR layer) on the second surface of the substrate of the present invention, which is an optical thin film with strictly controlled thickness and refractive index, or by laminating two or more of the optical thin films. The AR layer exhibits an anti-reflective function by utilizing the interference effect of light to cancel out the reversed phases of incident and reflected light. The wavelength range of visible light in which the anti-reflective function is exhibited is, for example, 380 to 780 nm, with the wavelength range of 450 to 650 nm being particularly sensitive, and it is preferable to design the AR layer to minimize the reflectance at the central wavelength of 550 nm.

[0064] Generally, the aforementioned anti-reflective (AR) layer is a multilayer anti-reflective layer with a structure in which two to five optical thin layers (thin films with precisely controlled thickness and refractive index) are stacked. By forming multiple layers of components with different refractive indices to a predetermined thickness, the degree of freedom in the optical design of the AR layer is increased, the anti-reflective effect can be further improved, and the spectral reflectance characteristics can be made uniform (flat) in the visible light region. Since high thickness accuracy is required for the aforementioned optical thin film, each layer is generally formed using dry methods such as vacuum deposition, sputtering, and CVD.

[0065] Furthermore, the AR layer can also be formed using a coating liquid for forming an anti-reflective layer. The coating liquid for forming an anti-reflective layer may contain, for example, a resin, a fluorine-containing additive, hollow particles, solid particles, and a diluent, and can be manufactured, for example, by mixing these.

[0066] Examples of the aforementioned resins include thermosetting resins and ionizing radiation-curable resins that harden with ultraviolet light or other light. Commercially available thermosetting resins and UV-curable resins can also be used as the aforementioned resin.

[0067] Examples of thermosetting resins and UV-curing resins include curable compounds having at least one of an acrylate group and a methacrylate group that harden by heat, light (such as ultraviolet light), or electron beams. Examples include oligomers or prepolymers of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols, such as acrylates or methacrylates. These may be used individually or in combination of two or more types.

[0068] The resin may also be a reactive diluent having at least one of an acrylate group and a methacrylate group. The reactive diluent may be, for example, a reactive diluent described in Japanese Patent Application Publication No. 2008-88309, and includes, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, etc. As the reactive diluent, a trifunctional or more acrylate or a trifunctional or more methacrylate is preferred. This is because it can improve the hardness of the second surface of the substrate of the present invention. Examples of the reactive diluent include butanediol glycerin ether diacrylate, isocyanuric acid acrylate, isocyanuric acid methacrylate, etc. These may be used individually or in combination of two or more. The weight-average molecular weight of the resin before curing may be, for example, 100 or more, 300 or more, 500 or more, 1,000 or more, or 2,000 or more, or it may be 100,000 or less, 70,000 or less, 50,000 or less, 30,000 or less, or 10,000 or less. If the weight-average molecular weight before curing is high, the hardness will decrease, but it tends to become less prone to cracking when bent. On the other hand, if the weight-average molecular weight before curing is low, the intermolecular crosslinking density will improve, and it tends to become harder.

[0069] The resin preferably includes a polyfunctional acrylate (for example, pentaslitol triacrylate).

[0070] For curing the curable resin, a curing agent may be added, for example. The curing agent is not particularly limited, and for example, known polymerization initiators (e.g., thermal polymerization initiators, photopolymerization initiators, etc.) can be used as appropriate. The amount of curing agent to be added is not particularly limited, but may be, for example, 0.5 parts by weight or more, 1.0 part by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight or more per 100 parts by weight of the resin in the anti-reflective layer forming coating liquid, or it may be 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less.

[0071] The fluorine-containing additive is not particularly limited, but may be, for example, an organic or inorganic compound containing fluorine in its molecule. The organic compound is not particularly limited, but may include, for example, a fluorine-containing antifouling coating agent, a fluorine-containing acrylic compound, or a fluorine and silicon-containing acrylic compound. Specifically, the organic compound may be, for example, "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd., or "Megafac" manufactured by DIC Corporation. The inorganic compound is also not particularly limited. The amount of the fluorine-containing additive added is not particularly limited, but may be, for example, 0.05% by weight or more, 0.1% by weight or more, 0.15% by weight or more, 0.20% by weight or more, or 0.25% by weight or more, relative to the total weight of the solids in the anti-reflective coating liquid, or it may be 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less. Furthermore, for example, the weight of the fluorine element-containing additive relative to 100 parts by weight of the resin in the anti-reflective coating liquid may be, for example, 0.05% by weight or more, 0.1% by weight or more, 0.15% by weight or more, 0.20% by weight or more, or 0.25% by weight or more, or 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less.

[0072] The hollow particles are not particularly limited, but may be, for example, silica particles, acrylic particles, acrylic-styrene copolymer particles, etc. Examples of silica particles include the product names "Thru-Ria 5320" and "Thru-Ria 4320" manufactured by JGC Catalysts & Chemicals Co., Ltd. The weight-average particle diameter of the hollow particles is not particularly limited, but may be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, or 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. The shape of the hollow particles is not particularly limited, and may be, for example, bead-like or roughly spherical, or amorphous such as powder, but roughly spherical is preferred, more preferably roughly spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. By adding the hollow particles, for example, a low refractive index and good anti-reflective properties of the anti-reflective layer can be achieved. The amount of hollow particles added is not particularly limited, but relative to 100 parts by weight of the resin in the anti-reflective coating liquid, it may be, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or more, or 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less. From the viewpoint of lowering the refractive index of the anti-reflective layer, it is preferable that the amount of hollow particles added is not too small, and from the viewpoint of ensuring the mechanical properties of the anti-reflective layer, it is preferable that the amount of hollow particles added is not too large.

[0073] The solid particles are not particularly limited, but may be, for example, silica particles, zirconium oxide particles, titanium-containing particles (e.g., titanium oxide particles), etc. Examples of silica particles include those manufactured by Nissan Chemical Industries, Ltd., such as "MEK-2140Z-AC," "MIBK-ST," and "IPA-ST." The weight-average particle diameter of the solid particles is not particularly limited, but may be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, or 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The shape of the solid particles is not particularly limited, and may be, for example, bead-like or substantially spherical, or amorphous such as powder, but substantially spherical is preferred, more preferably substantially spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. By adding the solid particles, for example, the fluorine-containing additive tends to be unevenly distributed on the surface of the coating liquid for forming the anti-reflective layer, resulting in excellent scratch resistance of the anti-reflective layer, a low refractive index, and good anti-reflective properties. The amount of solid particles added is not particularly limited, but may be, for example, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more per 100 parts by weight of the resin in the coating liquid for forming the anti-reflective layer, or it may be 150 parts by weight or less, 120 parts by weight or less, 100 parts by weight or less, or 80 parts by weight or less.

[0074] The dilution solvent may be, for example, a mixed solvent containing MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate). The mixing ratio in this case is not particularly limited, but if the weight of MIBK is 100% by weight, the weight of PMA may be, for example, 20% or more by weight, 50% or more by weight, 100% or more by weight, 150% or more by weight, or 200% or more by weight, or 400% or less by weight, 350% or less by weight, 300% or less by weight, or 250% or less by weight.

[0075] The dilution solvent may be, for example, a mixed solvent containing TBA (tert-butyl alcohol) in addition to MIBK and PMA. The mixing ratio in this case is not particularly limited, but if the weight of MIBK is 100% by weight, the weight of PMA may be, for example, 10% or more by weight, 30% or more by weight, 50% or more by weight, 80% or more by weight, or 100% or more by weight, or 200% or less by weight, 180% or less by weight, 150% or less by weight, 130% or less by weight, or 110% or less by weight. Also, if the weight of MIBK is 100% by weight, the weight of TBA may be, for example, 10% or more by weight, 30% or more by weight, 50% or more by weight, 80% or more by weight, or 100% or more by weight, or 200% or less by weight, 180% or less by weight, 150% or less by weight, 130% or less by weight, or 110% or less by weight.

[0076] The amount of diluting solvent added is not particularly limited, but for example, the weight of the solids relative to the total weight of the anti-reflective coating liquid may be, for example, 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, 1.0% by weight or more, or 1.5% by weight or more, or 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less. From the viewpoint of ensuring coating properties (wetting, leveling), it is preferable that the solids content is not too high, and from the viewpoint of preventing drying-related appearance defects such as uneven drying and whitening, it is preferable that the solids content is not too low.

[0077] Next, the anti-reflective layer forming coating liquid is applied to the second surface of the substrate of the present invention (the coating step). The coating method is not particularly limited, and known coating methods such as the fountain coating method, die coating method, spin coating method, spray coating method, gravure coating method, roll coating method, and bar coating method can be used as appropriate. The amount of the anti-reflective layer forming coating liquid applied is also not particularly limited, but the thickness of the formed anti-reflective layer may be, for example, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, or 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less.

[0078] Next, the applied anti-reflective coating liquid is dried to form a coating film (the coating film formation step). The drying temperature is not particularly limited, but may be in the range of 30 to 200°C, for example. The drying temperature may be 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, or 100°C or higher, and may be 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 135°C or lower, 130°C or lower, 120°C or lower, or 110°C or lower. The drying time is not particularly limited, but may be 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, and may be 150 seconds or less, 130 seconds or less, 110 seconds or less, or 90 seconds or less.

[0079] Furthermore, the coating film may be cured (curing step). Curing can be carried out, for example, by heating or light irradiation. The light is not particularly limited, but may be, for example, ultraviolet light. The light source for the light irradiation is also not particularly limited, but may be, for example, a high-pressure mercury lamp. The irradiation dose of the energy source in the ultraviolet curing is 50 to 500 mJ / cm² as the integrated exposure dose at an ultraviolet wavelength of 365 nm. 2 This is preferable. The irradiation dose is 50 mJ / cm². 2 If the above conditions are met, hardening will proceed more easily, and the hardness of the formed anti-reflective layer will tend to be higher. Also, 500 mJ / cm 2 The following conditions can prevent discoloration of the anti-reflective layer that is formed.

[0080] The aforementioned anti-glare (AG) treatment can be any known AG treatment without particular limitation, and can be carried out, for example, by forming an anti-glare layer on the second surface of the substrate of the present invention. The aforementioned anti-glare layer can be any known material without limitation, and is generally formed as a layer in which inorganic or organic particles are dispersed in a resin as an anti-glare agent.

[0081] The anti-glare layer is not particularly limited, but for example, it is formed using an anti-glare layer forming material containing a resin, particles, and a thixotropy imparter, and the particles and the thixotropy imparter aggregate to form convex portions on the surface of the anti-glare layer. With this configuration, the anti-glare layer has excellent display characteristics that combine anti-glare properties with prevention of white blurring, and despite being formed by utilizing particle aggregation, it is possible to prevent the occurrence of protrusions on the surface of the anti-glare layer that would be appearance defects, thereby improving the product yield.

[0082] Examples of the aforementioned resins include thermosetting resins and ionizing radiation-curable resins that harden with ultraviolet light or other light. Commercially available thermosetting resins and UV-curable resins can also be used as the aforementioned resin.

[0083] Examples of thermosetting resins and UV-curing resins include curable compounds having at least one of an acrylate group and a methacrylate group that harden by heat, light (such as ultraviolet light), or electron beams. Examples include oligomers or prepolymers of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols, such as acrylates or methacrylates. These may be used individually or in combination of two or more types.

[0084] The resin may also be a reactive diluent having at least one of an acrylate group and a methacrylate group. The reactive diluent may be, for example, the reactive diluent described in Japanese Patent Application Publication No. 2008-88309, and includes, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, etc. As the reactive diluent, a trifunctional or more acrylate or a trifunctional or more methacrylate is preferred. This is because it can provide excellent hardness to the anti-glare layer. Other examples of the reactive diluent include butanediol glycerin ether diacrylate, isocyanuric acid acrylate, isocyanuric acid methacrylate, etc. These may be used individually or in combination of two or more.

[0085] The aforementioned resin preferably contains a urethane acrylate resin, and more preferably is a copolymer of a curable urethane acrylate resin and a polyfunctional acrylate (e.g., pentaslitol triacrylate).

[0086] The particles for forming the anti-glare layer primarily function to impart anti-glare properties by creating an uneven surface on the formed anti-glare layer, and to control the haze value of the anti-glare layer. The haze value of the anti-glare layer can be designed by controlling the refractive index difference between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited and include, for example, silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, zirconium oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, calcium sulfate particles, etc. The organic particles are not particularly limited and include, for example, polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, etc. These inorganic and organic particles may be used individually or in combination of two or more types.

[0087] The weight-average particle size (D) of the particles is preferably within the range of 2.5 to 10 μm. By setting the weight-average particle size of the particles within this range, for example, superior anti-glare properties and prevention of white blurring can be achieved. The weight-average particle size of the particles is more preferably within the range of 3 to 7 μm. The weight-average particle size of the particles can be measured, for example, by the Coulter count method. For example, using a particle size distribution analyzer that utilizes the pore electrical resistance method (product name: Coulter Multisizer, manufactured by Beckman Coulter), the number and volume of the particles are measured by measuring the electrical resistance of the electrolyte corresponding to the volume of the particles as the particles pass through the pores, and the weight-average particle size is calculated.

[0088] The shape of the particles is not particularly limited; for example, they may be bead-like or roughly spherical, or they may be irregular in shape, such as powder. However, roughly spherical particles are preferred, more preferably roughly spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0089] The proportion of the particles in the anti-glare layer is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, and even more preferably in the range of 1 to 7 parts by weight, per 100 parts by weight of the resin. By setting it within this range, for example, superior anti-glare properties and prevention of whitening can be achieved.

[0090] The anti-glare layer may contain a thixotropy imparting agent. Including the thixotropy imparting agent makes it easy to control the aggregation state of the particles. Examples of thixotropy imparting agents for forming the anti-glare layer include organic clay, oxidized polyolefins, and modified urea.

[0091] The organic clay is preferably a clay that has been treated with organic compounds to improve its affinity with the resin. Examples of organic clay include layered organic clay. The organic clay may be prepared in-house or a commercially available product may be used. Examples of the aforementioned commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasif ME-100, Somasif MAE, Somasif MTE, Somasif MEE, Somasif MPE (product names, all manufactured by Coop Chemical Co., Ltd.); Esben, Esben C, Esben E, Esben W, Esben P, Esben WX, Esben N-400, Esben NX, Esben NX80, Esben NO12S, Esben NEZ, Esben NO12, Esben NE, Esben NZ, Esben NZ70, Organite, Organite D, Organite T (product names, all manufactured by Hojun Co., Ltd.); Kunipia F, Kunipia G, Kunipia G4 (product names, all manufactured by Kunimine Industries Co., Ltd.); Thixogel VZ, Clayton HT, Clayton 40 (product names, all manufactured by Lockwood Additives).

[0092] The oxidized polyolefin may be prepared in-house or a commercially available product may be used. Examples of commercially available products include Disparon 4200-20 (trade name, manufactured by Kusumoto Kasei Co., Ltd.) and Flownon SA300 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.).

[0093] The modified urea is a reaction product of an isocyanate monomer or its adduct with an organic amine. The modified urea may be prepared in-house or a commercially available product may be used. Examples of commercially available products include BYK410 (manufactured by Big Chemie).

[0094] The thixotropy-inducing agent may be used alone or in combination of two or more types.

[0095] Preferably, the height of the convex portion from the average roughness line of the anti-glare layer is less than 0.4 times the thickness of the anti-glare layer. More preferably, it is in the range of 0.01 times or more and less than 0.4 times, and even more preferably, in the range of 0.01 times or more and less than 0.3 times. Within this range, it is possible to effectively prevent the formation of protrusions that result in appearance defects on the convex portion. By having a convex portion of such height, the anti-glare layer can be made less prone to appearance defects. Here, the height from the average line can be measured, for example, by the method described in Japanese Patent Application Publication No. 2017-138620.

[0096] The proportion of the thixotropy imparting agent in the anti-glare layer is preferably in the range of 0.1 to 5 parts by weight, and more preferably in the range of 0.2 to 4 parts by weight, per 100 parts by weight of the resin.

[0097] The thickness (d) of the anti-glare layer is not particularly limited, but is preferably in the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer within this range, for example, curling of the optical adhesive sheet of the present invention can be prevented, and problems such as poor transportability and reduced productivity can be avoided. Furthermore, when the thickness (d) is within this range, the weight-average particle size (D) of the particles is preferably in the range of 2.5 to 10 μm, as described above. The combination of the thickness (d) of the anti-glare layer and the weight-average particle size (D) of the particles as described above can further improve the anti-glare properties. The thickness (d) of the anti-glare layer is more preferably in the range of 3 to 8 μm.

[0098] The relationship between the thickness (d) of the anti-glare layer and the weight-average particle size (D) of the particles is preferably within the range of 0.3 ≤ D / d ≤ 0.9. This relationship allows for a more superior anti-glare performance, prevention of whitening, and a free-looking anti-glare layer.

[0099] In the optical adhesive sheet of the present invention, as described above, the anti-glare layer forms convex portions on its surface by aggregation of the particles and the thixotropy imparting agent. In the aggregated portions forming the convex portions, the particles exist in a state where multiple particles are clustered together in the planar direction of the anti-glare layer. As a result, the convex portions have a smooth shape. By having convex portions of this shape, the anti-glare layer can maintain its anti-glare properties, prevent whitening, and further reduce the occurrence of appearance defects.

[0100] The surface shape of the anti-glare layer can be arbitrarily designed by controlling the aggregation state of particles contained in the anti-glare layer forming material. The aggregation state of the particles can be controlled, for example, by the material of the particles (e.g., the chemical modification state of the particle surface, affinity to solvents and resins, etc.), the type and combination of resin (binder) or solvent. Here, the aggregation state of the particles can be controlled by a thixotropy imparted agent contained in the anti-glare layer forming material. As a result, the aggregation state of the particles can be made as described above, and the convex portion can be made into a smooth shape.

[0101] In the optical adhesive sheet of the present invention, when the substrate of the present invention is formed from a resin or the like, it is preferable that a penetration layer is present at the interface between the substrate of the present invention and the anti-glare layer. The penetration layer is formed when the resin component contained in the anti-glare layer forming material penetrates into the substrate of the present invention. The formation of the penetration layer is preferable because it can improve the adhesion between the substrate of the present invention and the anti-glare layer. The thickness of the penetration layer is preferably in the range of 0.2 to 3 μm, and more preferably in the range of 0.5 to 2 μm. For example, if the substrate of the present invention is a polyester resin and the resin contained in the anti-glare layer is an acrylic resin, the penetration layer can be formed. The penetration layer can be confirmed, for example, by observing a cross-section of the optical adhesive sheet of the present invention with a transmission electron microscope (TEM), and its thickness can be measured.

[0102] Even when applied to an optical adhesive sheet having such a permeable layer, a desired smooth surface unevenness shape that achieves both anti-glare properties and prevention of white blurring can be easily formed. The permeable layer is preferably formed thicker to improve adhesion, especially when the substrate has poor adhesion to the anti-glare layer.

[0103] In the aforementioned anti-glare layer, an appearance defect with a maximum diameter of 200 μm or more occurs within 1 m of the anti-glare layer. 2 Preferably, there should be one or fewer defects per unit. More preferably, there should be no such cosmetic defects.

[0104] In the uneven surface shape of the anti-glare layer, the average inclination angle θa(°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5, even more preferably in the range of 1.0 to 4.0, and particularly preferably in the range of 1.6 to 4.0. Here, the average inclination angle θa is a value defined by the following formula (1). The average inclination angle θa is a value measured by, for example, the method described in Japanese Patent Application Publication No. 2017-138620. Average inclination angle θa=tan-1Δa (1)

[0105] In the above formula (1), Δa is the value obtained by dividing the sum of the differences (height h) between adjacent peaks and the lowest points of valleys (h1 + h2 + h3... + hn) in the reference length L of the roughness curve specified in JIS B 0601 (1994 edition) by the reference length L, as shown in the following formula (2). The roughness curve is a curve obtained by removing surface waviness components longer than a predetermined wavelength from the cross-sectional curve using a phase difference compensated high-pass filter. The cross-sectional curve is the contour that appears at the cut surface when the target surface is cut with a plane perpendicular to the target surface. Δa = (h1 + h2 + h3... + hn) / L (2)

[0106] When θa falls within the above range, it exhibits superior anti-glare properties and prevents white blurring.

[0107] In forming the anti-glare layer, it is preferable that the prepared anti-glare layer forming material (coating liquid) exhibits thixotropy, and that the Ti value defined below is preferably in the range of 1.3 to 3.5, and more preferably in the range of 1.3 to 2.8. Ti value = β1 / β2 Here, β1 is the viscosity measured using a HAAKE Rheostress 6000 under shear rate conditions of 20 (1 / s), and β2 is the viscosity measured using a HAAKE Rheostress 6000 under shear rate conditions of 200 (1 / s).

[0108] If the Ti value is less than 1.3, appearance defects are more likely to occur, and properties such as anti-glare and whiteness degradation deteriorate. Conversely, if the Ti value exceeds 3.5, the particles become less likely to aggregate and more likely to remain dispersed.

[0109] The method for manufacturing the anti-glare layer is not particularly limited and may be manufactured by any method. For example, it can be manufactured by preparing an anti-glare layer forming material (coating liquid) containing the resin, the particles, the thixotropy imparting agent, and the solvent, coating the anti-glare layer forming material (coating liquid) onto the second surface of the substrate of the present invention to form a coating film, and curing the coating film to form an anti-glare layer. Methods such as a mold transfer method, sandblasting, or embossing rolls to impart an uneven shape can also be used in combination.

[0110] The solvent is not particularly limited, and various solvents can be used. One type may be used alone, or two or more types may be used in combination. There is an optimal type of solvent and solvent ratio depending on the composition of the resin, the type and content of the particles and the thixotropy imparter. Examples of solvents are not particularly limited, but include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0111] When a polyester resin is used as the substrate for the present invention to form a permeable layer, a good solvent for the polyester resin can be suitably used. Examples of such solvents include ethyl acetate, methyl ethyl ketone, and cyclopentanone.

[0112] By appropriately selecting the aforementioned solvent, the thixotropy properties of the anti-glare layer-forming material (coating solution) can be effectively expressed by the thixotropy imparting agent. For example, when using organic clay, toluene and xylene can be suitably used individually or in combination. For example, when using oxidized polyolefin, methyl ethyl ketone, ethyl acetate, and propylene glycol monomethyl ether can be suitably used individually or in combination. For example, when using modified urea, butyl acetate and methyl isobutyl ketone can be suitably used individually or in combination.

[0113] Various leveling agents can be added to the anti-glare layer forming material. For example, fluorine-based or silicone-based leveling agents can be used to prevent uneven coating (uniformity of the coated surface). Depending on whether antifouling properties are required on the surface of the anti-glare layer, or whether an anti-reflective layer (low refractive index layer) or a layer containing an interlayer filler is formed on the anti-glare layer, the leveling agent can be appropriately selected. For example, by including the thixotropy imparting agent, thixotropy can be made to the coating liquid, making it less likely for uneven coating to occur. Therefore, this has the advantage of expanding the range of choices for the leveling agent.

[0114] The amount of the leveling agent is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight, per 100 parts by weight of the resin.

[0115] The anti-glare layer-forming material may, if necessary, contain pigments, fillers, dispersants, plasticizers, UV absorbers, surfactants, antifouling agents, antioxidants, etc., to the extent that it does not impair performance. These additives may be used individually or in combination of two or more types.

[0116] For the anti-glare layer forming material, for example, a conventionally known photopolymerization initiator, such as the one described in Japanese Patent Application Publication No. 2008-88309, can be used.

[0117] As a method for coating the anti-glare layer forming material onto the second surface of the substrate of the present invention, for example, coating methods such as the fountain coating method, die coating method, spin coating method, spray coating method, gravure coating method, roll coating method, and bar coating method can be used.

[0118] The anti-glare layer forming material is applied to the substrate of the present invention to form a coating film, and the coating film is cured. Prior to curing, it is preferable to dry the coating film. The drying may be, for example, natural drying, air drying by blowing air, heat drying, or a combination of these methods.

[0119] The means for curing the coating film of the anti-glare layer-forming material is not particularly limited, but ultraviolet curing is preferred. The irradiation dose of the energy source is 50 to 500 mJ / cm² as the integrated exposure dose at an ultraviolet wavelength of 365 nm. 2 This is preferable. The irradiation dose is 50 mJ / cm². 2 If the above is achieved, the hardening will be more sufficient, and the hardness of the formed anti-glare layer will also be more sufficient. 2 The following conditions can prevent discoloration of the anti-glare layer that is formed.

[0120] As described above, the anti-glare layer can be formed on the second surface of the substrate of the present invention. The anti-glare layer may also be formed by a manufacturing method other than the one described above. The hardness of the anti-glare layer is influenced by the thickness of the layer, but it is preferable that it has a hardness of 2H or higher on the pencil hardness scale.

[0121] The anti-glare layer may have a multi-layer structure in which two or more layers are stacked.

[0122] The aforementioned AR layer (low refractive index layer) may be placed on top of the anti-glare layer. For example, when an optical adhesive sheet is attached to an image display device, one of the factors that reduces the visibility of the image is the reflection of light at the interface between the air and the anti-glare layer. The AR layer reduces this surface reflection. The anti-glare layer and the anti-reflective layer may each have a multi-layer structure in which two or more layers are stacked.

[0123] Furthermore, in order to prevent the adhesion of contaminants and to improve the ease of removing any attached contaminants, it is preferable to laminate a contamination prevention layer formed from a fluorine-containing silane compound or a fluorine-containing organic compound, etc., on the anti-reflective layer and / or anti-glare layer.

[0124] It is preferable to perform a surface treatment on at least one of the substrate of the present invention and the anti-glare layer. Surface treatment of the substrate of the present invention further improves adhesion with the anti-glare layer. Surface treatment of the anti-glare layer further improves adhesion with the AR layer.

[0125] To prevent curling of the substrate of the present invention, the other surface of the anti-glare layer may be treated with a solvent. Alternatively, to prevent curling, a transparent resin layer may be formed on the other surface of the anti-glare layer.

[0126] <Adhesive layer> The adhesive layer of the present invention may be an adhesive layer without a substrate (substrate layer), or an adhesive layer of the type having a substrate. In this specification, an adhesive layer without a substrate (substrate layer) may be referred to as a "substrate-less adhesive layer," and an adhesive layer of the type having a substrate may be referred to as a "substrate-attached adhesive layer." Examples of the substrate-less adhesive layer include a single-layer adhesive layer consisting only of the adhesive layer of the present invention, and an adhesive layer consisting of the adhesive layer of the present invention and other adhesive layers (adhesive layers other than the adhesive layer of the present invention). Examples of the substrate-attached adhesive layer include an adhesive layer having the adhesive layer of the present invention on both sides of the substrate, and an adhesive layer having the adhesive layer of the present invention on one side of the substrate and other adhesive layers on the other side. As the "substrate (substrate layer)" constituting the "substrate-attached adhesive layer," a plastic film similar to the substrate of the present invention can be used.

[0127] The surface resistance value of the adhesive layer of the present invention is 10 10 It is less than Ω. The surface resistance of the adhesive layer of the present invention is 10 10 The configuration having a surface resistance of less than Ω is preferable because the adhesive layer of the present invention exhibits excellent antistatic effect, and it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of a bonding defect to the image display panel of the present invention. The surface resistance of the adhesive layer of the present invention is 0.97 × 10⁻¹⁰, which exhibits an even better antistatic effect and can more efficiently suppress the generation of static electricity during rework of the image display device of the present invention. 10 It is preferably less than or equal to Ω, and more preferably 0.96 × 10⁻¹⁰. 10 It is less than or equal to Ω, and more preferably 0.95 × 10⁻¹⁰. 10 It is less than or equal to Ω. The lower limit of the surface resistance of the adhesive layer of the present invention is not particularly limited, and a lower value is preferable, but 10 7 It may be Ω or higher.

[0128] The surface resistance value of the adhesive layer of the present invention after the following thermal shock test is 10 10 It is preferable that the value is less than Ω. • Thermal shock test The optical adhesive sheet of the present invention is subjected to thermal shock for 200 cycles using a thermal shock tester, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes.

[0129] The surface resistance value of the adhesive layer of the present invention after the above thermal shock test is 10 10 The configuration having a surface resistance of less than Ω is preferable because it allows the adhesive layer of the present invention to maintain excellent antistatic effect even in harsh environments such as thermal shock, and for example, when a malfunction such as non-illumination of a light-emitting element occurs in the operating environment of an image display device, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for repair. The surface resistance value of the adhesive layer of the present invention after the above thermal shock test is 0.97 × 10⁻¹⁰, which allows the adhesive layer of the present invention to maintain an even better antistatic effect in the operating environment of an image display device and to more efficiently suppress the generation of static electricity during rework for repair of the image display device of the present invention. 10 It is preferably less than or equal to Ω, and more preferably 0.96 × 10⁻¹⁰. 10 It is less than or equal to Ω, and more preferably 0.95 × 10⁻¹⁰. 10 It is less than or equal to Ω. The lower limit of the surface resistance value of the adhesive layer of the present invention after the above thermal shock test is not particularly limited, and a lower value is preferable, but 10 7 It may be Ω or higher.

[0130] The absolute difference in surface resistance values ​​of the adhesive layer of the present invention before and after the thermal shock test described above is calculated according to the following formula. |Log 10 B-Log 10 A| A: Surface resistance value before thermal shock test B: Surface resistance value after thermal shock test

[0131] The absolute value of the difference in surface resistance of the adhesive layer of the present invention before and after the above thermal shock test (|Log 10 B-Log 10A|) is preferably 1 log Ω or less. The configuration in which the difference in surface resistance of the adhesive layer of the present invention before and after the above thermal shock test is 1 log Ω or less is preferable because it allows the adhesive layer of the present invention to maintain an excellent antistatic effect even in harsh environments such as thermal shock, and for example, when a malfunction such as non-illumination of a light-emitting element occurs in the operating environment of an image display device, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for repair. More preferably, the difference in surface resistance of the adhesive layer of the present invention before and after the above thermal shock test is 0.9 log Ω or less, even more preferably 0.8 log Ω or less, and particularly preferably 0.7 log Ω or less, in which case the adhesive layer of the present invention can maintain an even better antistatic effect in the operating environment of an image display device and can more efficiently suppress the generation of static electricity during rework to repair the image display device of the present invention.

[0132] The surface resistivity of the adhesive layer of the present invention, the surface resistance value before and after the thermal shock test, and the difference therefrom are measured by the surface resistance value measurement in the examples described below. The surface resistivity of the adhesive layer of the present invention, the surface resistance value before and after the thermal shock test, and the difference therefrom can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0133] The hardness H [kPa] of the adhesive layer of the present invention, obtained by nanoindentation, is preferably less than 60 kPa. The configuration in which the hardness H [kPa] of the adhesive layer of the present invention, obtained by nanoindentation, is less than 60 kPa is preferable because, when there are uneven surfaces such as printed layers or wiring in image display panels or optical components, the adhesive layer of the present invention can sufficiently follow these steps and fill them without leaving air bubbles, etc., thus exhibiting excellent step absorption and preventing the above-mentioned bonding defects. In order to exhibit even better step absorption, the hardness H [kPa] of the adhesive layer of the present invention, obtained by nanoindentation, is preferably 55 kPa or less, more preferably 50 kPa or less, and may also be 45 kPa or less. The lower limit of the hardness H [kPa] of the adhesive layer of the present invention, obtained by nanoindentation, is preferably 1 kPa or more, and may also be 5 kPa or more, from the viewpoint of processability, such as preventing the adhesive layer from overflowing from the edges when storing the optical adhesive sheet of the present invention.

[0134] The hardness H of the adhesive layer of the present invention, as measured by the nanoindentation method, can be specifically measured by the method of the examples described below. The hardness H of the adhesive layer of the present invention, as measured by the nanoindentation method, can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0135] The glass transition temperature (Tg) of the adhesive layer of the present invention is preferably -10°C or lower. The configuration in which the Tg of the adhesive layer of the present invention is -10°C or lower is preferable because it can maintain the excellent step absorption properties of the adhesive layer of the present invention even in low-temperature environments. In order to maintain even better step absorption properties of the adhesive layer of the present invention even in low-temperature environments, the glass transition temperature of the adhesive layer of the present invention is preferably -15°C or lower, and may be -20°C or lower. The lower limit of the Tg of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of processability, such as the reduced likelihood of the adhesive layer overflowing from the edges during storage of the optical adhesive sheet of the present invention, it is preferably -50°C or higher, and may be -40°C or higher.

[0136] The glass transition temperature (Tg) of the adhesive layer of the present invention is measured by dynamic viscoelasticity measurement in the examples described below. The glass transition temperature (Tg) of the adhesive layer of the present invention can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0137] The storage modulus of the adhesive layer of the present invention at 25°C and 1 Hz is preferably less than 200 kPa. The configuration in which the storage modulus of the adhesive layer of the present invention at 25°C and 1 Hz is less than 200 kPa is preferable because the adhesive layer of the present invention can sufficiently follow the shrinkage or expansion under the operating environment of the image display device of the present invention, thereby suppressing lifting and peeling. Furthermore, it is preferable because it exhibits excellent step absorption when there are uneven shapes such as printed layers or wiring in the image display panel or optical components, and can prevent the above-mentioned bonding defects. In order to suppress lifting and peeling of the optical adhesive sheet of the present invention and to have superior step absorption, the storage modulus of the adhesive layer of the present invention at 25°C and 1 Hz is preferably 180 kPa or less, more preferably 160 kPa or less, even more preferably 140 kPa or less, and may also be 120 kPa or less. The lower limit of the storage modulus of the adhesive layer of the present invention at 25°C and 1 Hz is not particularly limited, but from the viewpoint of processability, such as preventing the adhesive layer from oozing out from the edges during storage of the optical adhesive sheet of the present invention, it is preferably 1 kPa or higher, and may be 5 kPa or higher.

[0138] The storage modulus of the adhesive layer of the present invention at 85°C and 1Hz is preferably less than 100kPa. The configuration in which the storage modulus of the adhesive layer of the present invention at 85°C and 1Hz is less than 100kPa is preferable because the adhesive layer of the present invention can sufficiently follow the shrinkage or expansion under the operating environment of the image display device of the present invention, thereby suppressing lifting and peeling. Furthermore, it is preferable because it exhibits excellent step absorption when there are uneven shapes such as printed layers or wiring in the image display panel or optical components, and can prevent the above-mentioned bonding defects. In order to suppress lifting and peeling of the optical adhesive sheet of the present invention and to have superior step absorption, the storage modulus of the adhesive layer of the present invention at 85°C and 1Hz is preferably 97kPa or less, more preferably 95kPa or less, even more preferably 92kPa or less, and may also be 90kPa or less. The lower limit of the storage modulus of the adhesive layer of the present invention at 85°C and 1 Hz is not particularly limited, but from the viewpoint of processability, such as preventing the adhesive layer from oozing out from the edges during storage of the optical adhesive sheet of the present invention, it is preferably 1 kPa or higher, and may be 5 kPa or higher.

[0139] The storage modulus of the adhesive layer of the present invention at 25°C or 85°C and 1 Hz is measured by dynamic viscoelasticity measurement in the examples described below. The storage modulus of the adhesive layer of the present invention at 25°C or 85°C and 1 Hz can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0140] The 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, but is 25 N / cm². 2 The following is preferable: The 300% tensile residual stress value of the adhesive layer of the present invention is 25 N / cm². 2 The following configuration is preferable because it allows the adhesive layer of the present invention to adequately follow the shrinkage or expansion under the operating environment of the image display device of the present invention, thereby suppressing lifting and peeling. Furthermore, it is preferable because it exhibits excellent step absorption when there are uneven shapes such as printed layers or wiring in the image display panel or optical components, and can prevent the above-mentioned bonding defects. In terms of suppressing lifting and peeling of the optical adhesive sheet of the present invention and having superior step absorption, the 300% tensile residual stress value of the adhesive layer of the present invention is 20 N / cm 2 The following is more preferable: 18 N / cm 2 The following is even more preferable: 15 N / cm 2 The following is also acceptable. The lower limit of the 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of processability, such as the reduced likelihood of the adhesive layer overflowing from the edges during storage of the optical adhesive sheet of the present invention, 1 N / cm is used. 2 The above is preferable, and 1.5 N / cm 2 That's fine too.

[0141] The 300% tensile residual stress value of the adhesive layer of the present invention is measured by the 300% tensile residual stress value measurement in the examples described below. The 300% tensile residual stress value of the adhesive layer of the present invention can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of functional groups, the type and amount of antistatic agent, the type and amount of crosslinking agent) and curing conditions (heating conditions, radiation irradiation conditions), etc.

[0142] The adhesive constituting the adhesive layer of the present invention is not particularly limited, but examples include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, and epoxy adhesives. Among these, acrylic adhesives are preferred as the adhesive constituting the adhesive layer in terms of transparency, tackiness, weather resistance, cost, and ease of designing the adhesive. In other words, the adhesive layer of the present invention is preferably an acrylic adhesive layer composed of an acrylic adhesive. The above adhesives can be used alone or in combination of two or more types.

[0143] The above-mentioned acrylic adhesive layer contains an acrylic polymer as a base polymer. The above-mentioned acrylic polymer is a polymer that contains an acrylic monomer (a monomer having a (meth)acryloyl group in its molecule) as a monomer component constituting the polymer. Preferably, the above-mentioned acrylic polymer is a polymer that contains an alkyl (meth)acrylate as a monomer component constituting the polymer. The acrylic polymer can be used alone or in combination of two or more types.

[0144] The adhesive composition forming the adhesive layer of the present invention may be in any form. For example, the adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray curing type, a hot melt type, etc. Among these, solvent type and active energy ray curing type adhesive compositions are preferred from the viewpoint of productivity and ease of obtaining an adhesive layer with excellent optical properties and appearance. In particular, an active energy ray curing type adhesive composition is preferred from the viewpoint of being able to easily control the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0145] In other words, the adhesive layer of the present invention is an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed by an active energy ray curable acrylic adhesive composition. Furthermore, the adhesive layer of the present invention is an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is also preferably formed by a solvent-type acrylic adhesive composition.

[0146] Examples of the active energy rays mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. In other words, the active energy ray curing type adhesive composition is preferably an ultraviolet-curing type adhesive composition.

[0147] Examples of adhesive compositions for forming the above-mentioned acrylic adhesive layer (acrylic adhesive compositions) include acrylic adhesive compositions comprising an acrylic polymer as an essential component, or acrylic adhesive compositions comprising a mixture of monomers constituting the acrylic polymer (sometimes referred to as a "monomer mixture") or a partially polymer thereof as an essential component. An example of the former is a so-called solvent-type acrylic adhesive composition. An example of the latter is a so-called active energy ray-curable acrylic adhesive composition. The above-mentioned "monomer mixture" means a mixture containing monomer components that constitute the polymer. The above-mentioned "partially polymerized product" may also be referred to as a "prepolymer," and means a composition in which one or more monomer components of the above-mentioned monomer mixture are partially polymerized.

[0148] The above acrylic polymer is a polymer composed (formed) using acrylic monomers as essential monomer components. Preferably, the above acrylic polymer is a polymer composed (formed) using alkyl (meth)acrylate as an essential monomer component. That is, it is preferable that the above acrylic polymer contains alkyl (meth)acrylate as a constituent unit. In this specification, "(meth)acrylic" means "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms. The above acrylic polymer is composed of one or more monomer components.

[0149] As the essential monomer component, alkyl (meth)acrylate esters having linear or branched alkyl groups are preferred. Alkyl (meth)acrylate esters can be used alone or in combination of two or more types.

[0150] The alkyl (meth)acrylate ester having a linear or branched alkyl group is not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth)acrylate. Examples of alkyl (meth)acrylates having a linear or branched alkyl group with 1 to 20 carbon atoms include nyl, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (stearyl (meth)acrylate), isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, the alkyl (meth)acrylate ester having a linear or branched alkyl group is preferably an alkyl (meth)acrylate ester having a linear or branched alkyl group with 4 to 18 carbon atoms, and more preferably 2-ethylhexyl acrylate (2EHA), isostearyl acrylate (ISTA), lauryl acrylate (LA), or butyl acrylate (BA). Furthermore, the alkyl (meth)acrylate ester having a linear or branched alkyl group can be used alone or in combination of two or more types.

[0151] The proportion of the alkyl (meth)acrylate in the total monomer components (100% by weight) constituting the above acrylic polymer is not particularly limited, but is preferably 50% by weight or more (for example, 50-100% by weight), more preferably 53-100% by weight, and even more preferably 55-100% by weight.

[0152] Furthermore, the acrylic adhesive composition may also contain the alkyl (meth)acrylate in addition to the acrylic polymer. When the acrylic adhesive composition contains the alkyl (meth)acrylate in addition to the acrylic polymer, the amount of the alkyl (meth)acrylate is preferably 10 parts by weight or more (for example, 10 to 100 parts by weight), more preferably 20 to 90 parts by weight, and even more preferably 30 to 80 parts by weight, per 100 parts by weight of the acrylic polymer.

[0153] The above-mentioned acrylic polymer may contain copolymerizable monomers as monomer components constituting the polymer, along with the above-mentioned alkyl (meth)acrylate. In other words, the above-mentioned acrylic polymer may contain copolymerizable monomers as constituent units. The copolymerizable monomers can be used alone or in combination of two or more types.

[0154] While the copolymerizable monomers mentioned above are not particularly limited, monomers having nitrogen atoms in their molecules and monomers having hydroxyl groups in their molecules are preferred from the viewpoint of easily controlling the various properties of the adhesive layer (especially step absorption) within a predetermined range, suppressing clouding in high humidity environments and improving durability, adhesive reliability, compatibility with various additives such as UV absorbers, and transparency. In other words, it is preferable that the above acrylic polymer contains monomers having nitrogen atoms in their molecules as constituent units. Furthermore, it is preferable that the above acrylic polymer contains monomers having hydroxyl groups in their molecules as constituent units.

[0155] The monomers having a nitrogen atom in their molecule are monomers (monomers) that have at least one nitrogen atom in their molecule (one molecule). In this specification, the above "monomers having a nitrogen atom in their molecule" may be referred to as "nitrogen atom-containing monomers." The above nitrogen atom-containing monomers are not particularly limited, but cyclic nitrogen-containing monomers and (meth)acrylamides are preferred examples. Nitrogen atom-containing monomers can be used alone or in combination of two or more types.

[0156] The above-mentioned cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure. The above-mentioned cyclic nitrogen structure is preferably one in which a nitrogen atom is contained within the cyclic structure.

[0157] Examples of the cyclic nitrogen-containing monomers mentioned above include N-vinyl cyclic amides (lactam-based vinyl monomers) and vinyl monomers having nitrogen-containing heterocycles.

[0158] Examples of the above-mentioned N-vinylcyclic amides include N-vinylcyclic amides represented by the following formula (1). [ka] (In formula (1), R 1 (This indicates a divalent organic group.)

[0159] R in equation (1) above 1 is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms).

[0160] Examples of N-vinyl cyclic amides represented by formula (1) above include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholindione.

[0161] Examples of vinyl monomers having nitrogen-containing heterocycles include acrylic monomers having nitrogen-containing heterocycles such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings.

[0162] The above-mentioned vinyl monomers having a nitrogen-containing heterocycle are not particularly limited, but examples include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine.

[0163] Among the above-mentioned vinyl monomers having a nitrogen-containing heterocycle, acrylic monomers having a nitrogen-containing heterocycle are preferred, and more preferably (meth)acryloylmorpholine, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine.

[0164] Examples of the above (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, and N,N-dialkyl(meth)acrylamide. Examples of the above N-alkyl(meth)acrylamides include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, and N-octyl(meth)acrylamide. Furthermore, the above N-alkyl(meth)acrylamides also include (meth)acrylamides having an amino group, such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide. Examples of the above-mentioned N,N-dialkyl(meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide.

[0165] Furthermore, the above-mentioned (meth)acrylamides also include, for example, various N-hydroxyalkyl (meth)acrylamides. Examples of the above-mentioned N-hydroxyalkyl (meth)acrylamides include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

[0166] Furthermore, the above-mentioned (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides. Examples of the above-mentioned N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

[0167] Furthermore, examples of nitrogen atom-containing monomers other than the above-mentioned cyclic nitrogen-containing monomers and (meth)acrylamides include amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, and isocyanate group-containing monomers. Examples of the above-mentioned amino group-containing monomers include (meth)acrylate aminoethyl, (meth)acrylate dimethylaminoethyl, (meth)acrylate dimethylaminopropyl, and (meth)acrylate t-butylaminoethyl. Examples of the above-mentioned cyano group-containing monomers include acrylonitrile and methacrylonitrile. Examples of the above-mentioned imide group-containing monomers include maleimide monomers (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide, etc.), and succinimide monomers (e.g., N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc.). Examples of the above-mentioned isocyanate group-containing monomers include 2-(meth)acryloyloxyethyl isocyanate.

[0168] Among the nitrogen atom-containing monomers mentioned above, cyclic nitrogen-containing monomers are preferred, and N-vinyl cyclic amides are more preferred. More specifically, N-vinyl-2-pyrrolidone (NVP) is particularly preferred.

[0169] When the above acrylic polymer contains the nitrogen atom-containing monomer as a monomer component constituting the polymer, the proportion of the nitrogen atom-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more. When the above proportion is 1% by weight or more, the suppression of clouding in high humidity environments and durability are further improved, and high adhesive reliability can be obtained, which is preferable. Furthermore, the upper limit of the proportion of the nitrogen atom-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility, an adhesive layer with excellent transparency, and easy control of the above various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0170] The monomers having a hydroxyl group in their molecule are monomers that have at least one hydroxyl group in their molecule (one molecule), and preferably have a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also have a hydroxyl group. However, the monomers having a hydroxyl group in their molecule do not include the nitrogen atom-containing monomers. That is, in this specification, monomers having both a nitrogen atom and a hydroxyl group in their molecule are included in the above-mentioned "nitrogen atom-containing monomers". In this specification, the above-mentioned "monomers having a hydroxyl group in their molecule" may be referred to as "hydroxyl group-containing monomers". Hydroxyl group-containing monomers can be used alone or in combination of two or more types.

[0171] Examples of the hydroxyl group-containing monomers mentioned above include hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl) (meth)acrylic acid; vinyl alcohol; and allyl alcohol.

[0172] Among these, hydroxyl group-containing monomers are preferably hydroxyl group-containing (meth)acrylic acid esters, and more preferably 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA).

[0173] When the above-mentioned acrylic polymer contains the above-mentioned hydroxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the above-mentioned hydroxyl group-containing monomer in the total monomer components (100% by weight) constituting the above-mentioned acrylic polymer is not particularly limited, but is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, and even more preferably 1% by weight or more, from the viewpoint of suppressing clouding in high humidity environments, improving durability, and obtaining high adhesive reliability. Furthermore, the upper limit of the proportion of the above-mentioned hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less, from the viewpoint of easily controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0174] Furthermore, in order to further enhance the above-mentioned effects of the hydroxyl group-containing monomer, the acrylic adhesive composition may also contain a hydroxyl group-containing monomer in addition to the acrylic polymer. When the acrylic adhesive composition contains a hydroxyl group-containing monomer in addition to the acrylic polymer, the content (amount blended) of the hydroxyl group-containing monomer is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and even more preferably 5 parts by weight or more, per 100 parts by weight of the acrylic polymer. When the above content is 5 parts by weight or more, the suppression of clouding in high humidity environments and durability are further improved, and higher adhesive reliability can be obtained, which is preferable. Furthermore, the upper limit of the content (amount blended) of the hydroxyl group-containing monomer is more preferably 30 parts by weight or less, more preferably 25 parts by weight or less, even more preferably 20 parts by weight or less, and particularly preferably 17 parts by weight or less, from the viewpoint of cohesive force, adhesion, ease of obtaining adhesive reliability, and ease of controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0175] The total proportion of nitrogen atom-containing monomers and hydroxyl group-containing monomers in the total monomer components (100% by weight) constituting the above acrylic polymer is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more, from the viewpoint of suppressing clouding in high humidity environments, improving durability, and obtaining high adhesive reliability. Furthermore, the upper limit of the above total proportion is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility, an adhesive layer with excellent transparency, and easy control of the above various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0176] Besides nitrogen atom-containing monomers and hydroxyl group-containing monomers, copolymerizable monomers other than carboxyl group-containing monomers can also be cited. The above carboxyl group-containing monomers are not particularly limited as long as they have a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also have a carboxyl group. Examples of carboxyl group-containing monomers include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and also include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride. Carboxyl group-containing monomers can be used alone or in combination of two or more types.

[0177] When the above-mentioned acrylic polymer contains the above-mentioned carboxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the above-mentioned carboxyl group-containing monomer in the total monomer components (100% by weight) constituting the above-mentioned acrylic polymer is not particularly limited, but is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, and even more preferably 1% by weight or more, from the viewpoint of obtaining high adhesive reliability. Furthermore, the upper limit of the proportion of the above-mentioned carboxyl group-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less, from the viewpoint of easily controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0178] Besides nitrogen atom-containing monomers and hydroxyl group-containing monomers, copolymerizable monomers other than alicyclic structure-containing monomers can also be mentioned. The above alicyclic structure-containing monomers are not particularly limited as long as they have polymerizable functional groups having unsaturated double bonds, such as (meth)acryloyl groups or vinyl groups, and have an alicyclic structure. For example, alkyl (meth)acrylates having cycloalkyl groups are included in the above alicyclic structure-containing monomers. Alicyclic structure-containing monomers can be used alone or in combination of two or more types.

[0179] The alicyclic structure in the above-mentioned alicyclic structure-containing monomer is a cyclic hydrocarbon structure, preferably having 5 or more carbon atoms, more preferably 6 to 24 carbon atoms, even more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 10 carbon atoms.

[0180] Examples of monomers containing the above-mentioned alicyclic structure include (meth)acrylic monomers such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, HPMPA represented by formula (2) below, TMA-2 represented by formula (3) below, and HCPA represented by formula (4) below. In formula (4) below, the bonding site between the cyclohexyl ring connected by a line and the structural formula in parentheses is not particularly limited. Among these, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferred.

[0181] [ka] [ka] [ka]

[0182] When the above-mentioned acrylic polymer contains the above-mentioned alicyclic structure-containing monomer as a monomer component constituting the polymer, the proportion of the above-mentioned alicyclic structure-containing monomer in the total monomer components (100% by weight) constituting the above-mentioned acrylic polymer is not particularly limited, but is preferably 10% by weight or more from the viewpoint of improving durability and obtaining high adhesive reliability. Furthermore, the upper limit of the proportion of the above-mentioned alicyclic structure-containing monomer is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less from the viewpoint of obtaining an adhesive layer with appropriate flexibility and easily controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range.

[0183] Furthermore, examples of copolymerizable monomers include polyfunctional monomers. Examples of the above polyfunctional monomers include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. Polyfunctional monomers can be used individually or in combination of two or more.

[0184] When the above-mentioned acrylic polymer contains the above-mentioned polyfunctional monomer as a monomer component constituting the polymer, the proportion of the above-mentioned polyfunctional monomer in the total monomer components (100% by weight) constituting the above-mentioned acrylic polymer is not particularly limited, but from the viewpoint of easily controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range, it is preferably 0.5% by weight or less (for example, greater than 0% by weight and 0.5% by weight or less), and more preferably 0.2% by weight or less (for example, greater than 0% by weight and 0.2% by weight or less).

[0185] Furthermore, the polyfunctional monomer may be incorporated into the acrylic adhesive composition in addition to the acrylic polymer. When the acrylic adhesive composition contains a polyfunctional monomer in addition to the acrylic polymer, the content (amount of incorporation) of the polyfunctional monomer is preferably 0.5 parts by weight or less (for example, greater than 0 parts by weight and less than or equal to 0.5 parts by weight) and more preferably 0.2 parts by weight or less (for example, greater than 0 parts by weight and less than or equal to 0.2 parts by weight) per 100 parts by weight of the acrylic polymer, from the viewpoint of easily controlling the various properties of the adhesive layer (particularly step absorption) within a predetermined range.

[0186] Furthermore, examples of copolymerizable monomers include alkoxyalkyl esters of (meth)acrylate. While the alkoxyalkyl esters of (meth)acrylate are not particularly limited, examples include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. Among these, alkoxyalkyl esters of acrylate are preferred, and 2-methoxyethyl acrylate (MEA) is more preferred. The alkoxyalkyl esters of (meth)acrylate can be used alone or in combination of two or more.

[0187] When the above acrylic polymer contains the above (meth)acrylate alkoxyalkyl ester as a monomer component constituting the polymer, the ratio of the above (meth)acrylate alkyl ester to the above (meth)acrylate alkoxyalkyl ester is not particularly limited, but is preferably greater than 100:0 and 25:75 or less in weight ratio, and more preferably greater than 100:0 and 50:50 or less.

[0188] Other copolymerizable monomers include, for example, epoxy group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, (meth)acrylic acid esters having aromatic hydrocarbon groups, vinyl esters, aromatic vinyl compounds, olefins or dienes, vinyl ethers, and vinyl chloride. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of sulfonic acid group-containing monomers include sodium vinylsulfonate. Examples of phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of (meth)acrylic acid esters having aromatic hydrocarbon groups include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Examples of vinyl esters include vinyl acetate and vinyl propionate. Examples of aromatic vinyl compounds include styrene and vinyltoluene. Examples of olefins or dienes include ethylene, propylene, butadiene, isoprene, and isobutylene. Examples of the vinyl ethers mentioned above include vinyl alkyl ethers.

[0189] The content of the base polymer (particularly acrylic polymer) in the adhesive layer of the present invention is not particularly limited, but is preferably 50% by weight or more (e.g., 50-100% by weight) based on 100% by weight of the total weight of the adhesive layer of the present invention, more preferably 80% by weight or more (e.g., 80-100% by weight), and even more preferably 90% by weight or more (e.g., 90-100% by weight).

[0190] The weight-average molecular weight (Mw) of the above acrylic polymer is 100,000 to 5,000,000, preferably 500,000 to 4,000,000, and more preferably 750,000 to 3,000,000. A configuration in which the weight-average molecular weight of the acrylic polymer is 100,000 or more is preferable in that it improves adhesive strength and foam peel resistance. On the other hand, a configuration in which the weight-average molecular weight of the acrylic polymer is 5,000,000 or less is preferable in that it is easier to increase adhesive strength and improve foam peel resistance.

[0191] The weight-average molecular weight (Mw) of the above acrylic polymer can be determined by converting it to polystyrene equivalent using the GPC method. For example, it can be measured using the high-speed GPC instrument "HPLC-8120GPC" manufactured by Tosoh Corporation under the following conditions. Column: TSKgel SuperHZM-H / HZ4000 / HZ3000 / HZ2000 Solvent: tetrahydrofuran Flow rate: 0.6ml / min

[0192] The glass transition temperature (Tg) of the above acrylic polymer is not particularly limited, but is preferably -70 to -10°C, more preferably -65 to -15°C, and even more preferably -60 to -20°C. A glass transition temperature of -70°C or higher for the acrylic polymer is preferable because it improves cohesive strength and easily improves foaming and peeling resistance. Furthermore, a configuration in which the glass transition temperature of the acrylic polymer is -10°C or lower is preferable because it maintains the stress relaxation properties of the adhesive layer even in low-temperature environments, the adhesive layer can sufficiently follow the shrinkage or expansion under the usage environment of the image display device of the present invention, suppress lifting and peeling, and ensure sufficient adhesion to the adherend.

[0193] The glass transition temperature (Tg) of the above acrylic polymer is the theoretical value of the glass transition temperature expressed by the following FOX equation. 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + W n / Tg n In the above formula, Tg is the glass transition temperature of the acrylic polymer (unit: K), Tgi This is the glass transition temperature (unit: K) when monomer i forms a homopolymer, W i represents the weight fraction of monomer i in the total amount of monomer components (i = 1, 2, .... n). The following values ​​can be used as the Tg of the monomer homopolymer constituting the above acrylic polymer. 2-Ethylhexyl acrylate -70℃ n-hexyl acrylate -65℃ n-Octylacrylate -65℃ Isononyl acrylate -60℃ n-nonyl acrylate -58℃ n-butyl acrylate -55℃ Ethyl acrylate -20℃ Lauryl acrylate 0℃ 2-Ethylhexyl methacrylate -10℃ Methyl acrylate 8℃ n-butyl methacrylate 20℃ Methyl methacrylate 105℃ Acrylic acid 106℃ Methacrylic acid 228℃ Vinyl acetate 32℃ Styrene 100℃

[0194] Furthermore, for monomer homopolymers not listed above, the Tg values ​​listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) can be used. In addition, for monomer homopolymers not listed in the above literature, the values ​​obtained by the measurement method described above (tanδ peak top temperature by viscoelasticity test) can be used.

[0195] The base polymer, such as the acrylic polymer described above, contained in the adhesive layer of the present invention is obtained by polymerizing monomer components. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). Among these, solution polymerization and active energy ray polymerization are preferred from the viewpoint of transparency of the adhesive layer and cost, and active energy ray polymerization is more preferred.

[0196] Furthermore, various common solvents may be used in the polymerization of the above monomer components. Examples of such solvents 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 organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvents can be used individually or in combination of two or more.

[0197] When polymerizing the above monomer components, polymerization initiators such as thermal polymerization initiators and photopolymerization initiators (photoinitiators) may be used depending on the type of polymerization reaction. Polymerization initiators can be used alone or in combination of two or more types.

[0198] The above-mentioned thermal polymerization initiators are not particularly limited, but examples include azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), and redox polymerization initiators. Among these, the azo polymerization initiator disclosed in Japanese Patent Application Publication No. 2002-69411 is preferred. Examples of the above-mentioned azo polymerization initiators include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN"), 2,2'-azobis-2-methylbutyronitrile (hereinafter sometimes referred to as "AMBN"), 2,2'-azobis(2-methylpropionic acid)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. The thermal polymerization initiators can be used alone or in combination of two or more.

[0199] When the above-mentioned azo polymerization initiator is used during the polymerization of the above-mentioned acrylic polymer, the amount of the azo polymerization initiator used is not particularly limited, but for example, it is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and also preferably 0.5 parts by weight or less, and more preferably 0.3 parts by weight or less, per 100 parts by weight of the total monomer components constituting the above-mentioned acrylic polymer.

[0200] The above-mentioned photopolymerization initiators are not particularly limited, but examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Other examples include acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators. Examples of the above-mentioned 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-diphenylethane-1-one, and anisole methyl ether. Examples of the above acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of the above α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of the above aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of the above photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the above benzoin-based photopolymerization initiators include benzoin. Examples of the above benzyl-based photopolymerization initiators include benzyl. Examples of the benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the ketal-based photopolymerization initiators include benzyldimethyl ketal.Examples of the thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Examples of the titanocene-based photopolymerization initiators include bis(η. 5 Examples include -2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium. The photopolymerization initiator can be used alone or in combination of two or more.

[0201] When the above-mentioned photopolymerization initiator is used during the polymerization of the above-mentioned acrylic polymer, the amount of the photopolymerization initiator used is not particularly limited, but for example, it is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, and more preferably 1.5 parts by weight or less, per 100 parts by weight of the total monomer components constituting the above-mentioned acrylic polymer.

[0202] The adhesive layer of the present invention contains a liquid antistatic agent. The antistatic agent imparts antistatic properties to the adhesive layer of the present invention, and is preferable in that it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel. Furthermore, the configuration in which the antistatic agent is liquid is preferable in that it can impart an excellent antistatic effect to the adhesive layer of the present invention without impairing the adhesive properties of the adhesive layer of the present invention, thereby improving the adhesion between the adhesive layer of the present invention and the substrate of the present invention, and obtaining excellent thermal shock resistance.

[0203] The above-mentioned liquid antistatic agent is not particularly limited, but examples include ionic liquids, alkali metal salts, and ionic group-containing silicones. Ionic liquids are preferred because they can impart an excellent antistatic effect to the adhesive layer of the present invention without impairing the adhesive properties of the adhesive layer of the present invention, thereby improving adhesion between the adhesive layer of the present invention and the substrate of the present invention, and resulting in excellent thermal shock resistance. The liquid antistatic agent can be used alone or in combination of two or more types.

[0204] The aforementioned ionic liquid is a molten salt (ionic compound) that is liquid at room temperature (25°C). The ionic liquid can be easily added to, dispersed in, or dissolved in the adhesive layer of the present invention, and its molecular motion is readily apparent. It is believed that excellent antistatic properties can be obtained without impairing the adhesive properties.

[0205] Preferably, the ionic liquid used consists of an organic cation component represented by the following formulas (A) to (E) and an anionic component. These cation-containing ionic liquids provide an adhesive layer with even better antistatic properties.

[0206] [ka]

[0207] R in equation (A) above a R represents a divalent hydrocarbon group having 4 to 20 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a heteroatom (e.g., oxygen atom, nitrogen atom, sulfur atom, etc.; the same applies hereinafter), b and R c R may be the same or different, representing hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a functional group in which part of the hydrocarbon group is substituted with a heteroatom. However, if the nitrogen atom (N) contains a double bond, c There isn't one.

[0208] R in equation (B) above dR represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a heteroatom. e , R f , and R g These may be identical or different functional groups representing hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, wherein a portion of the hydrocarbon group is substituted with a heteroatom.

[0209] R in equation (C) above h R represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a heteroatom. i , R j , and R k These may be identical or different functional groups representing hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, wherein a portion of the hydrocarbon group is substituted with a heteroatom.

[0210] In formula (D) above, Z represents a nitrogen, sulfur, or phosphorus atom, and R l , R m , R n , and R o R may be the same or different hydrocarbon group having 1 to 20 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a heteroatom. However, if Z is a sulfur atom, R o There isn't one.

[0211] R in equation (E) above P This represents a hydrocarbon group having 1 to 18 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a heteroatom.

[0212] Examples of cations represented by formula (A) include pyridinium cations, piperidinium cations, pyrrolidinium cations, cations with a pyrroline skeleton, cations with a pyrrole skeleton, and morpholinium cations.

[0213] Specific examples of cations represented by formula (A) include, for example, 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation, and 1-methylpyrrolidinium cation. Tyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium cation, 1-ethyl-1-propylpyrrolidinium cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium cation, 1,1-dipropylpyrrolidinium cation, 1-propyl- 1-Butylpyrrolidinium cation, 1,1-Dibutylpyrrolidinium cation, Pyrrolidinium-2-one cation, 1-Propylpiperidinium cation, 1-Pentylpiperidinium cation, 1,1-Dimethylpiperidinium cation, 1-Methyl-1-ethylpiperidinium cation, 1-Methyl-1-propylpiperidinium cation, 1-Methyl-1-butylpiperidinium cation, 1-Methyl-1-pentylpiperidinium cation, 1-Methyl-1-hexylpiperidinium cation, 1-Methyl-1-hexylpiperidinium cation Tylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl-1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation, 2-methyl-1-pyrroline cation, 1-ethyl-2-phenylindole cation, 1,Examples include 2-dimethylindole cation, 1-ethylcarbazole cation, and N-ethyl-N-methylmorpholinium cation.

[0214] Examples of cations represented by formula (B) include imidazolium cation, tetrahydropyrimidinium cation, and dihydropyrimidinium cation.

[0215] Specific examples of cations represented by formula (B) include, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3-dimethylimidazolium cation, and 1-(2-methoxyethyl)-3-methylimidazolium cation. Examples include lium cation, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, and 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium cation.

[0216] Examples of the cation represented by formula (C) include a pyrazolium cation, a pyrazolinium cation, and the like.

[0217] Specific examples of the cation represented by formula (C) include, for example, 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, 1-ethyl-2,3,5-trimethylpyrazolium cation, 1-propyl-2,3,5-trimethylpyrazolium cation, 1-butyl-2,3,5-trimethylpyrazolium cation, 1-ethyl-2,3,5-trimethylpyrazolinium cation, 1-propyl-2,3,5-trimethylpyrazolinium cation, 1-butyl-2,3,5-trimethylpyrazolinium cation, and the like.

[0218] Examples of the cation represented by formula (D) include, for example, a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, and those in which a part of the alkyl group is substituted with an alkenyl group, an alkoxyl group, or further an epoxy group.

[0219] Specific examples of cations represented by formula (D) include, for example, tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, diallyldimethylammonium cation, and tributyl-(2-methoxyethyl)phosphonium cation. Among them are asymmetric tetraalkylammonium cations such as triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, trimethyldecylphosphonium cation, as well as N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N-dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl-N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-diethyl-N-propyl-N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl-N-hexylammonium cation, N,N-dimethyl-N-propyl-N-heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-diethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexylammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N-pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N,N-dipropyl-N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation are preferably used.,

[0220] Examples of the cation represented by the formula (E) include sulfonium cation and the like. Further, R in the formula (E) PSpecific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, an octadecyl group, and the like.

[0221] On the other hand, the anion component is not particularly limited as long as it satisfies the condition of forming an ionic liquid. For example, Cl - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , C4F9SO3 - , (CF3SO2)2N - , (C2F5SO2)2N - , (C3F7SO2)2N - , (C4F9SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , F(HF) n - , (CN)2N - , C4F9SO3 - , (C2F5SO2)2N - , C3F7COO - , (CF3SO2)(CF3CO)N - , C9H 19 COO - , (CH3)2PO4 - , (C2H5)2PO4 - , C2H5OSO3 - , C6H 13 OSO3 - , C8H 17 OSO3 - , CH3(OC2H4)2OSO3 - , C6H4(CH3)SO3 -(C2F5)3PF3 - CH3CH(OH)COO - , and (FSO2)2N - These are some examples of what is used.

[0222] Furthermore, anions represented by the following formula (F) can also be used as anionic components. [ka]

[0223] Among the anionic components, those containing fluorine atoms are particularly preferred because they yield ionic liquids with low melting points. The ionic liquid preferably contains an anionic component with 10 or fewer fluorine atoms. The configuration in which the ionic liquid contains an anionic component with 10 or fewer fluorine atoms is preferable because it improves the compatibility of the ionic liquid with the adhesive layer of the present invention, suppresses the increase in haze due to the separation of the ionic liquid from the adhesive layer, and improves the visibility of the image display device. From the viewpoint of improving the compatibility of the ionic liquid with the adhesive layer of the present invention and suppressing the increase in haze of the adhesive layer, the number of fluorine atoms contained in the anionic component of the ionic liquid is more preferably 8 or fewer, and even more preferably 6. The lower limit of the number of fluorine atoms contained in the anionic component of the ionic liquid is preferably 4 or more, from the viewpoint of obtaining an ionic liquid with a low melting point.

[0224] Specific examples of ionic liquids used in the present invention include those appropriately selected from the above-mentioned combinations of cationic and anionic components, such as 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium hexafluorophosphate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylpyridinium bis(pentafluoro Roethanesulfonyl)imide, 1-hexylpyridinium tetrafluoroborate, 1,1-dimethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-hexylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-hexylpyrrolidinium bis(trifluoromethanesulfonyl)imide Honyl)imide, 1-ethyl-1-heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(triple oromethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(triple oromethanesulfonyl)imide, 1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-pentylbiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-Dimethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-ethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-propylpiperidinium bis (Trifluoromethanesulfonyl)imide, 1-ethyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-Dimethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-ethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-1-butylpyrrolidinium Umbis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-Dimethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-ethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl- 1-Butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(pentafluoroethanesulfonyl)imide, 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, 1-ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium di Cyanamide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(nonafluorobutylsulfonyl)imide, 1-ethyl-3-methylimidazolium tris(trifluoromethanesulfonyl)methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium Trifluoroacetate, 1-butyl-3-methylimidazolium heptafluorobutyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazoly Um hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-methylpyrazolium tetrafluoroborate, 2-methylpyrazolium tetrafluoroporate, 1-ethyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-Propyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Propyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Propyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl) Trifluoroacetamide, 1-ethyl-2,3,5-trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-propyl-2,3,5-trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-butyl-2,3,5-trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-2,3,5-trimethylpyrazolinium bis(pentafluoroethanesulfonyl)imide, 1-butyl-2,3,5-trimethylpyrazolinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-2,3,5-trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-propyl-2,3,5-trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-butyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, tetrapentylammonium trifluoromethanesulfonate, tetrapentylammonium bis(trifluoromethanesulfonyl)imide, tetrahexylammonium trifluoromethanesulfonate, tetrahexylammonium bis(trifluoromethanesulfonyl)imide, tetrahebutylammonium trifluoromethanesulfonate, tetraheptylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium bis(pentafluoroethanesulfonyl)imide, N,N-diethyl-N-methyl-N-(2-methoxye, N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium trifluoromethanesulfonate, N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(pentafluoroethanesulfonyl)imide, Glycidyltrimethylammonium trifluoromethanesulfonate, Glycidyltrimethylammonium bis(trifluoromethanesulfonyl )imide, glycidyltrimethylammonium bis(pentafluoroethanesulfonyl)imide, tetraoctylphosphonium trifluoromethanesulfonate, tetraoctylphosphonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide N,N-dimethyl-N-ethyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-nonylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dipropylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N ,N-dimethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-pentyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, triethylpropylammonium Bis(trifluoromethanesulfonyl)imide, triethylpentylammonium bis(trifluoromethanesulfonyl)imide, triethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-ethylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,Examples include N-dibutyl-N-methyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, 1-butylpyridinium(trifluoromethanesulfonyl)trifluoroacetamide, 1-butyl-3-methylpyridinium(trifluoromethanesulfonyl)trifluoroacetamide, 1-ethyl-3-methylimidazolium(trifluoromethanesulfonyl)trifluoroacetamide, N-ethyl-N-methylmorpholinium thiocyanate, and 4-ethyl-4-methylmorpholinium methyl carbonate. These ionic liquids may be used individually or in mixtures of two or more.

[0225] The content of the liquid antistatic agent in the adhesive layer (particularly the acrylic adhesive layer) of the present invention is not particularly limited, but it is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 1.5 parts by weight or more, per 100 parts by weight of the base polymer, in order to efficiently suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel. Furthermore, the upper limit of the content of the liquid antistatic agent is not particularly limited, but from the viewpoint of the visibility of the image display device, it is preferably 20 parts by weight or less, and more preferably 15 parts by weight or less, per 100 parts by weight of the base polymer.

[0226] The above acrylic adhesive composition preferably contains, together with the above acrylic polymer, an acrylic oligomer having a weight-average molecular weight of 1,000 to 30,000. The inclusion of an acrylic oligomer improves the adhesion to the substrate at the interface of the optical adhesive sheet of the present invention, making it easier to obtain strong adhesion and excellent resistance to foaming and peeling. In this specification, "acrylic oligomer having a weight-average molecular weight of 1,000 to 30,000" may simply be referred to as "acrylic oligomer."

[0227] As the above acrylic oligomer, acrylic polymers composed of (meth)acrylic acid ester having a cyclic structure in the molecule as an essential monomer component are preferred, and acrylic polymers composed of (meth)acrylic acid ester having a cyclic structure in the molecule and (meth)acrylic acid alkyl ester having a linear or branched alkyl group as essential monomer components are preferred. In other words, as the above acrylic oligomer, acrylic polymers containing (meth)acrylic acid ester having a cyclic structure in the molecule as a monomer unit are preferred, and acrylic polymers containing (meth)acrylic acid ester having a cyclic structure in the molecule and (meth)acrylic acid alkyl ester having a linear or branched alkyl group as monomer units are preferred.

[0228] The cyclic structure (ring) of the above-mentioned (meth)acrylic acid ester having a cyclic structure within the molecule (within one molecule) (hereinafter sometimes referred to as "ring-containing (meth)acrylic acid ester") may be either an aromatic ring or a non-aromatic ring, and is not particularly limited. Examples of the aromatic ring include aromatic carbocyclic rings [for example, monocyclic carbocyclic rings such as benzene rings, or fused carbocyclic rings such as naphthalene rings], and various aromatic heterocyclic rings. Examples of the above-mentioned non-aromatic rings include non-aromatic aliphatic rings (non-aromatic alicyclic rings) [e.g., cycloalkane rings such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane rings; cycloalkene rings such as cyclohexene rings, etc.], non-aromatic bridged rings [e.g., bicyclic hydrocarbon rings in pinane, pinene, bornane, norbornane, norbornene, etc.; triplicate or more aliphatic hydrocarbon rings (bridged hydrocarbon rings) in adamantane, etc.], and non-aromatic heterocycles [e.g., epoxy rings, oxolane rings, oxetane rings, etc.].

[0229] Examples of the above-mentioned aliphatic hydrocarbon rings with three or more rings (cross-linked hydrocarbon rings with three or more rings) include the dicyclopentanyl group represented by formula (5a), the dicyclopentenyl group represented by formula (5b), the adamantyl group represented by formula (5c), the tricyclopentanyl group represented by formula (5d), and the tricyclopentenyl group represented by formula (5e). [ka]

[0230] In other words, the above-mentioned ring-containing (meth)acrylic acid esters include, for example, cycloalkyl (meth)acrylic acid esters such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, and 1-adamantine Examples include (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings, such as phthal(meth)acrylate, 2-methyl-2-adamantyl(meth)acrylate, and 2-ethyl-2-adamantyl(meth)acrylate; and (meth)acrylic acid esters having aromatic rings, such as aryl (meth)acrylate esters like phenyl(meth)acrylate, aryloxyalkyl (meth)acrylate esters like phenoxyethyl(meth)acrylate, and arylalkyl (meth)acrylate esters like benzyl(meth)acrylate. Among these, non-aromatic ring-containing (meth)acrylic acid esters are particularly preferred as the above ring-containing (meth)acrylic acid esters, more preferably cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), dicyclopentanyl acrylate (DCPA), and dicyclopentanyl methacrylate (DCPMA), and even more preferably dicyclopentanyl acrylate (DCPA) and dicyclopentanyl methacrylate (DCPMA). Furthermore, ring-containing (meth)acrylic acid esters may be used alone or in combination of two or more types.

[0231] Among the non-aromatic ring-containing (meth)acrylic acid esters mentioned above, (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings (especially three or more cross-linked hydrocarbon rings) are particularly preferred because they are less likely to inhibit polymerization. Furthermore, when (meth)acrylic acid esters having a dicyclopentanyl group represented by formula (5a), an adamantyl group represented by formula (5c), or a tricyclopentanyl group represented by formula (5d) that do not have an unsaturated bond are used, foam peel resistance can be further improved, and adhesion to low-polarity substrates such as polyethylene and polypropylene can be significantly improved.

[0232] The content (percentage) of the above-mentioned ring-containing (meth)acrylic acid ester in the total monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but is preferably 10 to 90 parts by weight, and more preferably 20 to 80 parts by weight, based on the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). A content of 10 parts by weight or more of the above-mentioned ring-containing (meth)acrylic acid ester is preferable because it tends to improve foam peel resistance. Furthermore, a content of 90 parts by weight or less is preferable because the adhesive layer has appropriate flexibility, which tends to improve adhesive strength and step absorption.

[0233] Furthermore, examples of alkyl (meth)acrylates having the above-mentioned linear or branched alkyl group as monomer units of acrylic oligomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and 2-ethyl (meth)acrylate. Examples include alkyl esters of (meth)acrylates having 1 to 20 carbon atoms in the alkyl group, such as xyl, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, methyl methacrylate (MMA) is preferred because it has good compatibility with acrylic polymers. The above alkyl esters of (meth)acrylates may be used alone or in combination of two or more.

[0234] The content (percentage) of the alkyl (meth)acrylate having the linear or branched alkyl group in the total monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but in terms of resistance to foaming and peeling, it is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, and even more preferably 20 to 60 parts by weight, per 100 parts by weight of the total amount of monomer components constituting the acrylic oligomer. A content of 10 parts by weight or more is particularly preferable because it tends to improve adhesion to substrates made of acrylic resin or polycarbonate.

[0235] In addition to the ring-containing (meth)acrylic acid esters and alkyl (meth)acrylic acid esters having linear or branched alkyl groups, monomers capable of copolymerizing with these monomers (copolymerizable monomers) may also be included as monomer units in the acrylic oligomer. The content (percentage) of the copolymerizable monomer in the total monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but is preferably 49.9 parts by weight or less (for example, 0 to 49.9 parts by weight) and more preferably 30 parts by weight or less, based on the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). Furthermore, copolymerizable monomers may be used alone or in combination of two or more types.

[0236] Examples of the copolymerizable monomer as a monomer unit of the acrylic oligomer (the copolymerizable monomer constituting the acrylic oligomer) include, for example, alkoxyalkyl (meth)acrylate [e.g., 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxy triethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, etc.]; hydroxyl group-containing monomers [e.g., hydroxyalkyl (meth)acrylate such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, vinyl alcohol, allyl alcohol, etc.]; amide group-containing monomers [e.g., (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, etc.]; amino group-containing monomers [e.g., aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, etc.]; cyano group-containing monomers [e.g., acrylonitrile, methacrylonitrile, etc.]; sulfonic acid group-containing monomers [e.g., sodium vinyl sulfonate, etc.]; phosphate group-containing monomers [e.g., 2-hydroxyethyl acryloyl phosphate, etc.]; isocyanate group-containing monomers [e.g., 2-methacryloyloxyethyl isocyanate, etc.], imide group-containing monomers [cyclohexyl maleimide, isopropyl maleimide, etc.], and the like.

[0237] As described above, the acrylic oligomer is preferably an acrylic polymer containing a (meth)acrylate ester having a cyclic structure within the molecule and an alkyl (meth)acrylate having a linear or branched alkyl group as monomer units. In particular, it is preferable that the acrylic polymer contains a ring-containing (meth)acrylate ester and the alkyl (meth)acrylate having the linear or branched alkyl group as monomer units. In the acrylic polymer containing a ring-containing (meth)acrylate ester and an alkyl (meth)acrylate having a linear or branched alkyl group as monomer units, the amount of ring-containing (meth)acrylate ester relative to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight) is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight. Furthermore, the content of alkyl (meth)acrylate having a linear or branched alkyl group is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, and even more preferably 20 to 60 parts by weight.

[0238] Furthermore, particularly preferred specific compositions of acrylic oligomers include acrylic polymers containing (1) at least one monomer selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate, and (2) methyl methacrylate as monomer units. In the above particularly preferred specific compositions of acrylic oligomers, the content of (1) dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate (the total amount if two or more are included) in the total monomer units of the acrylic oligomer is preferably 30 to 70 parts by weight, and the content of (2) methyl methacrylate is preferably 30 to 70 parts by weight, relative to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). However, the above acrylic oligomers are not limited to the above specific compositions.

[0239] Acrylic oligomers can be obtained by polymerizing the above monomer components by known or conventional polymerization methods. Examples of polymerization methods for acrylic oligomers include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). Among these, bulk polymerization and solution polymerization are preferred, and solution polymerization is more preferred.

[0240] Various common solvents may be used in the polymerization of acrylic oligomers. Examples of such solvents 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 organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used individually or in combination of two or more.

[0241] Furthermore, known or conventional polymerization initiators (e.g., thermal polymerization initiators or photopolymerization initiators) may be used during the polymerization of acrylic oligomers. The polymerization initiators may be used individually or in combination of two or more.

[0242] Examples of thermal polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 1,1'-azobis(cyclohexane-1- Examples of azo initiators include carbonitrine, 2,2'-azobis(2,4,4-trimethylpentane), and peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane. When performing solution polymerization, it is preferable to use an oil-soluble polymerization initiator. Furthermore, thermal polymerization initiators may be used alone or in combination of two or more.

[0243] The amount of thermal polymerization initiator used is not particularly limited, but for example, it is 0.1 to 15 parts by weight per 100 parts by weight of the total monomer units of the acrylic oligomer (total amount of monomer components constituting the acrylic oligomer).

[0244] Furthermore, the above-mentioned photopolymerization initiator is not particularly limited, but for example, the same photopolymerization initiator used in the polymerization of the acrylic polymers mentioned above can be used. The amount of the above-mentioned photopolymerization initiator used is not particularly limited and can be selected as appropriate.

[0245] In polymerization of the above acrylic oligomers, a chain transfer agent may be used to adjust the molecular weight (specifically, to adjust the weight-average molecular weight to 1,000 to 30,000). Examples of such chain transfer agents include 2-mercaptoethanol, α-thioglycerol, 2,3-dimercapto-1-propanol, octyl mercaptan, t-nonyl mercaptan, dodecyl mercaptan (lauryl mercaptan), t-dodecyl mercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, thioglycolic acid ester of pentaerythritol, and α-methylstyrene dimer. In particular, from the viewpoint of suppressing the whitening of the optical adhesive sheet of the present invention due to humidification, α-thioglycerol and methyl thioglycolate are preferred, and α-thioglycerol is especially preferred. The chain transfer agent may be used alone or in combination of two or more types.

[0246] The content (amount used) of the above-mentioned chain transfer agent is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and even more preferably 0.3 to 10 parts by weight, per 100 parts by weight of the total monomer units (total amount of monomer components constituting the acrylic oligomer) of the acrylic oligomer. By setting the content (amount used) of the chain transfer agent within the above range, an acrylic oligomer with a weight-average molecular weight controlled to 1000 to 30000 can be easily obtained.

[0247] The weight-average molecular weight (Mw) of the above acrylic oligomer is 1,000 to 30,000, preferably 1,000 to 20,000, more preferably 1,500 to 10,000, and even more preferably 2,000 to 8,000. Since the weight-average molecular weight of the acrylic oligomer is 1,000 or more, adhesive strength and retention properties are improved, and foam peel resistance is enhanced. On the other hand, since the weight-average molecular weight of the acrylic oligomer is 30,000 or less, it is easier to increase adhesive strength and foam peel resistance is enhanced.

[0248] The weight-average molecular weight (Mw) of the above acrylic oligomer can be determined by converting it to polystyrene equivalent using the GPC method. For example, it can be measured using the high-speed GPC instrument "HPLC-8120GPC" manufactured by Tosoh Corporation under the following conditions. Column: TSKgel SuperHZM-H / HZ4000 / HZ3000 / HZ2000 Solvent: tetrahydrofuran Flow rate: 0.6ml / min

[0249] The glass transition temperature (Tg) of the above acrylic oligomer is not particularly limited, but is preferably 20 to 300°C, more preferably 30 to 300°C, and even more preferably 40 to 300°C. A glass transition temperature of 20°C or higher for the acrylic oligomer is preferable because it easily improves foaming and peel resistance. Furthermore, a glass transition temperature of 300°C or lower for the acrylic oligomer is preferable because the adhesive layer has appropriate flexibility, making it easier to obtain good adhesive strength and good step absorption, and thus easier to obtain excellent adhesive reliability.

[0250] The glass transition temperature (Tg) of the above acrylic oligomer is the glass transition temperature (theoretical value) expressed by the above FOX equation. The Tg values ​​listed in Table 1 below can be used for the monomer homopolymers constituting the above-mentioned acrylic oligomers. For monomer homopolymers not listed in Table 1, the values ​​listed in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) can be used. Furthermore, for monomer homopolymers not listed in the above-mentioned literature, the values ​​obtained by the measurement method described above (tanδ peak top temperature by viscoelasticity testing) can be used.

[0251] [Table 1] Note that in Table 1, the copolymer "DCPMA / MMA=60 / 40" refers to a copolymer consisting of 60 parts by weight of DCPMA and 40 parts by weight of MMA.

[0252] When the above acrylic adhesive composition contains an acrylic polymer and an acrylic oligomer, the content of the acrylic oligomer is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, per 100 parts by weight of the acrylic polymer. That is, the content of the acrylic oligomer in the above adhesive composition is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, per 100 parts by weight of the total monomer units of the acrylic polymer. The content of the acrylic oligomer in the above acrylic adhesive composition is not particularly limited, but for example, is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 2 to 10 parts by weight, per 100 parts by weight of the monomer mixture. When the content of the acrylic oligomer is 1 part by weight or more, it is easier to obtain excellent adhesion and excellent foaming resistance, which is preferable. Furthermore, a content of acrylic oligomer of 30 parts by weight or less is preferable, as it makes it easier to obtain excellent transparency and adhesive reliability. Also, from the viewpoint of easily controlling the above-mentioned various properties of the adhesive layer (especially step absorption) within a predetermined range, a content of acrylic oligomer of 10 parts by weight or less is preferable, and 8 parts by weight or less is more preferable.

[0253] The method for producing the above-mentioned adhesive composition containing an acrylic polymer and an acrylic oligomer is not particularly limited. For example, it can be produced by adding an acrylic oligomer, additives, etc., as needed to a mixture of monomer components constituting the acrylic polymer or a partially polymerized mixture of monomer components constituting the acrylic polymer (a monomer mixture that forms an acrylic polymer or a partially polymer thereof), and then mixing the mixture.

[0254] The adhesive layer of the present invention is not particularly limited, but it is preferable that it contains an ultraviolet absorber (UVA). The presence of an ultraviolet absorber in the adhesive layer of the present invention is preferable because it can suppress damage to the image display panel caused by ultraviolet light. The ultraviolet absorber can be used alone or in combination of two or more types.

[0255] The above-mentioned UV absorbers are not particularly limited, but examples include benzotriazole-based UV absorbers, hydroxyphenyltriazine-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, and oxybenzophenone-based UV absorbers.

[0256] Examples of benzotriazole-based UV absorbers (benzotriazole compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), benzenepropanoic acid and ester compounds of 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side chain and linear alkyl) (trade name "TINUVIN 384-2", manufactured by BASF), octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate and a mixture of 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate (trade name "TINUVIN Reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (product name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (product name "TINUVIN 928", manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (product name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (product name "TINUVIN P (manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-Tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-Methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360", manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb" Examples include "250" (manufactured by Sumitomo Chemical Co., Ltd.) and 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (product name "ADEKA Stab LA-31", manufactured by ADEKA Corporation).

[0257] Examples of hydroxyphenyltriazine-based UV absorbers (hydroxyphenyltriazine compounds) include the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), and the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (trade name "TINUVIN 400"). 405 (manufactured by BASF), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (product name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (product name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (product name "ADEKA Stab LA-46", manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (product name "TINUVIN Examples include "TINUVIN 479" (manufactured by BASF). Another example is the compound represented by the following formula (6) (trade name "TINUVIN 477", manufactured by BASF). [ka]

[0258] Examples of benzophenone-based UV absorbers (benzophenone compounds) and oxybenzophenone-based UV absorbers (oxybenzophenone compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone (trade name "KEMISORB 111", manufactured by Chemipro Chemical Co., Ltd.), 2,2',4,4'-tetrahydroxybenzophenone (trade name "SEESORB 106", manufactured by Cipro Chemical Co., Ltd.), and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0259] Examples of salicylic acid ester-based UV absorbers (salicylic acid ester compounds) include phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (trade name "TINUVIN 120", manufactured by BASF).

[0260] Examples of cyanoacrylate-based ultraviolet absorbers (cyanoacrylate compounds) include alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, and alkynyl 2-cyanoacrylate.

[0261] As the above-mentioned ultraviolet absorber, at least one ultraviolet absorber selected from the group consisting of benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and hydroxyphenyltriazine ultraviolet absorbers is preferred, in order to have high ultraviolet absorption while further improving corrosion resistance (especially UV resistance), excellent optical properties, ease of obtaining an adhesive layer with high transparency, and excellent photostability, and benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers are more preferred. In particular, benzotriazole ultraviolet absorbers in which a phenyl group having a group with 6 or more carbon atoms and a hydroxyl group as substituents is bonded to the nitrogen atom constituting the benzotriazole ring is preferred.

[0262] Furthermore, the above-mentioned ultraviolet absorber is preferably such that the absorbance A, as determined below, is 0.5 or less, in order to obtain higher ultraviolet absorption and further improve corrosion resistance (especially UV resistance). Absorbance A: Absorbance measured when a 0.08% toluene solution of the UV absorber is exposed to light with a wavelength of 400 nm.

[0263] When the adhesive layer of the present invention contains an ultraviolet absorber, the amount of the ultraviolet absorber in the adhesive layer of the present invention (particularly the acrylic adhesive layer) is not particularly limited, but from the viewpoint of further improving corrosion resistance (particularly UV resistance), it is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more, per 100 parts by weight of the base polymer. Furthermore, the upper limit of the amount of the ultraviolet absorber is preferably 10 parts by weight or less, more preferably 9 parts by weight or less, and even more preferably 8 parts by weight or less, per 100 parts by weight of the base polymer, from the viewpoint of suppressing the occurrence of yellowing of the adhesive due to the addition of the ultraviolet absorber and obtaining excellent optical properties, high transparency, and excellent appearance properties.

[0264] The adhesive layer of the present invention may contain a light stabilizer. If the adhesive layer of the present invention contains a light stabilizer, it is particularly preferable to contain the light stabilizer together with the above-mentioned ultraviolet absorber. The light stabilizer can capture radicals generated by photo-oxidation, thereby improving the resistance of the adhesive layer to light (especially ultraviolet light). The light stabilizer can be used alone or in combination of two or more types.

[0265] The above-mentioned light stabilizers are not particularly limited, but examples include phenolic light stabilizers (phenolic compounds), phosphorus light stabilizers (phosphorus compounds), thioether light stabilizers (thioether compounds), and amine light stabilizers (amine compounds) (especially hindered amine stabilizers (hindered amine compounds)).

[0266] Examples of the above-mentioned phenolic light stabilizers (phenolic compounds) include 2,6-di-tertiary butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tertiary butylphenol, 2,6-di-tertiary butyl-4-ethylphenol, butylated hydroxyanisole, n-octadecyl 3-(4-hydroxy-3,5-di-tertiary butylphenyl)propionate, distearyl(4-hydroxy-3-methyl-5-tertiary butyl)benzylmalonate, tocopherol, and 2,2'-methylenebis(4-methyl-6-tertiary butylphenyl) ,2'-methylenebis(4-ethyl-6-tertiary butylphenol), 4,4'-methylenebis(2,6-di-tertiary butylphenol), 4,4'-butylidenebis(6-tertiary butyl-m-cresol), 4,4'-thiobis(6-tertiary butyl-m-cresol), styrene phenol, N,N'-hexamethylenebis(3,5-di-tertiary butyl-4-hydroxyhydrocinnamide), bis(3,5-di-tertiary butyl-4-hydroxybenzylphosphonate ethyl ester) calcium, 1,1,3-tris(2-methyl-4-hydroxy Droxy-5-tertiary butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tertiary butyl-4-hydroxybenzyl)benzene, tetrakis[3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionyloxymethyl]methane, 1,6-hexanediol-bis[3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-crezo [Tri-butyl-3-hydroxy-2,6-dimethylbenzyl]isocyanuric acid, 1,3,5-tris(3,5-di-tertiary-butyl-4-hydroxybenzyl)isocyanuric acid, triethylene glycol-bis[3-(3-tertiary-butyl-4-hydroxy-5-methylphenyl)propionate], 2,2'-oxamide bis[ethyl3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate], 6-(4-hydroxy-3,5-di-tertiary-butylanilino)-2,4-dioctylthio-1,3,Examples include 5-triazine, bis[2-tertiary butyl-4-methyl-6-(2-hydroxy-3-tertiary butyl-5-methylbenzyl)phenyl]terephthalate, 3,9-bis{2-[3-(3-tertiary butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-bis{2-[3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0267] Examples of phosphorus-based light stabilizers (phosphorus compounds) include trisnonylphenyl phosphite, tris(2,4-di-tertiary butylphenyl) phosphite, tris[2-tertiary butyl-4-(3-tertiary butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl] phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, di(tridecyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tertiary butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tertiary butyl-4-methylphenyl)pentaerythritol diphosphite, bis( Examples include 2,4,6-tri-tertiary butylphenyl) pentaerythritol diphosphite, tetra(tridecyl)isopropylidene diphenol diphosphite, tetra(tridecyl)-4,4'-n-butylidenebis(2-tertiary butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tertiary butylphenyl) butane triphosphite, tetrakis(2,4-di-tertiary butylphenyl) biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and tris(2-[(2,4,8,10-tetrakis-tertiary butyldibenzo[d,f][1,3,2]dioxaphosphine-6-yl)oxy]ethyl)amine.

[0268] Examples of thioether-based light stabilizers (thioether compounds) include dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl, and distearyl; and β-alkyl mercaptopropionate ester compounds of polyols such as tetrakis[methylene(3-dodecylthio)propionate]methane.

[0269] Examples of amine-based light stabilizers (amine compounds) include polymers of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name "TINUVIN 622", manufactured by BASF), and the 1:1 reaction product of polymers of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidine-4-yl)amino)-triazine-2-yl)-4,7-diazadecane-1,10-diamine (trade name "TINUVIN 622"). 119", manufactured by BASF, dibutylamine·1,3-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine polycondensate (product name "TINUVIN 2020", manufactured by BASF), poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2-4-diyl}{2,2,6,6-tetramethyl-4-piperidyl}imino]hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino} (product name "TINUVIN 944 (manufactured by BASF), a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 765", manufactured by BASF), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (trade name "TINUVIN 770", manufactured by BASF), reaction product of bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) decandioate, 1,1-dimethylethyl hydroperoxide and octane (trade name "TINUVIN 770"). 123", manufactured by BASF, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (trade name "TINUVIN 144", manufactured by BASF), cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1,3,Examples include the reaction product of 5-triazine and 2-aminoethanol (trade name "TINUVIN 152", manufactured by BASF), a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 292", manufactured by BASF), and a mixed ester of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (trade name "ADEKA Stab LA-63P", manufactured by ADEKA Corporation). Among amine-based stabilizers, hindered amine-based stabilizers are particularly preferred.

[0270] When the adhesive layer of the present invention contains a light stabilizer, the content of the light stabilizer in the adhesive layer of the present invention (particularly the acrylic adhesive layer) is not particularly limited, but is preferably 0.1 parts by weight or more, and more preferably 0.2 parts by weight or more, per 100 parts by weight of the base polymer, in order to facilitate the development of resistance to light. Furthermore, the upper limit of the above content is preferably 5 parts by weight or less, and more preferably 3 parts by weight or less, per 100 parts by weight of the base polymer, in order to reduce the likelihood of discoloration caused by the light stabilizer itself, to facilitate the acquisition of high transparency, and in terms of optical properties.

[0271] The formation of the adhesive layer of the present invention is not particularly limited, but a crosslinking agent may be used. For example, the acrylic polymer in the acrylic adhesive layer can be crosslinked to control the gel fraction. The crosslinking agent can be used alone or in combination of two or more types.

[0272] The above-mentioned crosslinking agents are not particularly limited, but examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred, and isocyanate-based crosslinking agents are more preferred.

[0273] Examples of the above-mentioned isocyanate-based crosslinking agents (polyfunctional isocyanate compounds) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. In addition, commercially available isocyanate-based crosslinking agents include, for example, trimethylolpropane / tolylene diisocyanate adduct (product name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate adduct (product name "Coronate HL", manufactured by Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane / xylylene diisocyanate adduct (product name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc.).

[0274] Examples of the epoxy crosslinking agents (polyfunctional epoxy compounds) mentioned above include N,N,N',N'-tetraglycidyl-m-xylenediline, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples of epoxy crosslinking agents include diglycidyl ethers, glycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycerol polyglycidyl ethers, sorbitan polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, diglycidyl adipate esters, diglycidyl o-phthalate esters, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ethers, bisphenol-S-diglycidyl ethers, and epoxy resins having two or more epoxy groups in the molecule. In addition, commercially available epoxy crosslinking agents such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Co., Ltd.) can also be used.

[0275] When a crosslinking agent is used to form the adhesive layer of the present invention, the amount of the crosslinking agent used is not particularly limited, but from the viewpoint of obtaining sufficient adhesive reliability, it is preferably 0.001 parts by weight or more, and more preferably 0.01 parts by weight or more, per 100 parts by weight of the base polymer. Furthermore, the upper limit of the amount used is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, per 100 parts by weight of the base polymer, from the viewpoint of obtaining appropriate flexibility in the adhesive layer, improving adhesive strength, and easily controlling the above-mentioned various properties of the adhesive layer (particularly step absorption) within a predetermined range.

[0276] The adhesive layer of the present invention (particularly the acrylic adhesive layer) may contain a silane coupling agent to improve adhesive reliability under humid conditions, and especially to improve adhesive reliability to glass. The silane coupling agent can be used alone or in combination of two or more types. When the adhesive layer contains a silane coupling agent, the adhesion under humid conditions, particularly to glass, can be improved.

[0277] The silane coupling agent mentioned above is not particularly limited, but examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-aminopropyltrimethoxysilane. Furthermore, commercially available silane coupling agents such as the trade name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.) are also available. Among these, γ-glycidoxypropyltrimethoxysilane is preferred as the silane coupling agent.

[0278] When the adhesive layer of the present invention contains a silane coupling agent, the content of the silane coupling agent in the adhesive layer of the present invention (particularly the acrylic adhesive layer) is not particularly limited, but is preferably 0.01 parts by weight or more, and more preferably 0.02 parts by weight or more, per 100 parts by weight of the base polymer. Furthermore, the upper limit of the content of the silane coupling agent is preferably 1 part by weight or less, and more preferably 0.5 parts by weight or less, per 100 parts by weight of the base polymer.

[0279] The adhesive layer of the present invention may contain a coloring agent. The coloring agent can be used alone or in combination of two or more types. The inclusion of a coloring agent in the adhesive layer is preferable because it can prevent reflections caused by metal wiring, ITO wiring, etc., arranged on the substrate of the image display device of the present invention.

[0280] The coloring agent may be a dye or a pigment, as long as it is soluble or dispersible in the adhesive layer of the present invention. Dyes are preferred because they can achieve low haze even with small amounts of addition, and they do not settle like pigments, making them easy to distribute uniformly. Pigments are also preferred because they exhibit high color development even with small amounts of addition. When using a pigment as the coloring agent, it is preferable that it has low or no conductivity. When using a dye, it is preferable to use it in combination with the above-mentioned light stabilizer, etc.

[0281] The aforementioned coloring agent can be any coloring agent that absorbs visible light (wavelength 400-700 nm) and is transparent to ultraviolet light (wavelength 330-400 nm), or absorbs ultraviolet light, without limitation. However, it is preferable that the coloring agent absorbs visible light and is ultraviolet light transparent. In other words, it is preferable that the maximum transmittance at wavelengths of 330-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. It is also preferable that the average transmittance at wavelengths of 330-400 nm is greater than the average transmittance at wavelengths of 400-700 nm. The transmittance of the coloring agent is measured using a solution or dispersion diluted with an appropriate solvent or dispersion medium such as tetrahydrofuran (THF) or an organic solvent with low absorption in the wavelength range of 330-700 nm, so that the transmittance at wavelength 400 nm is about 50-60%.

[0282] Carbon black and titanium black, commonly used as black colorants, absorb ultraviolet light more than visible light (their ultraviolet transmittance is lower than their visible light transmittance). Therefore, when a colorant such as carbon black is added to an active energy ray curing type acrylic adhesive composition, much of the ultraviolet light irradiated for photocuring is absorbed by the colorant, reducing the amount of light absorbed by the photopolymerization initiator, and thus requiring more time for photocuring (resulting in a higher cumulative irradiation dose). Furthermore, when the adhesive layer is thick, less ultraviolet light reaches the surface opposite the light-irradiated surface, leading to insufficient photocuring even with prolonged light irradiation. In contrast, using a colorant with a higher ultraviolet transmittance than visible light can suppress curing inhibition caused by the colorant.

[0283] Examples of UV-transmitting black pigments include Tokushiki's "9050BLACK" and "UVBK-0001". Examples of UV-absorbing black dyes include Orient Chemical Industry's "VALIFAST BLACK 3810" and "NUBIAN Black PA-2802". Examples of UV-absorbing black pigments include carbon black and titanium black.

[0284] The colorant content in the adhesive layer of the present invention is, for example, about 0.01 to 20 parts by weight per 100 parts by weight of the base polymer, and can be appropriately set depending on the type of colorant, the color tone of the adhesive layer, and the light transmittance. The colorant may also be added to the composition as a solution or dispersion obtained by dissolving or dispersing it in a suitable solvent.

[0285] The adhesive layer of the present invention may optionally contain additives such as crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, fillers, antioxidants, chain transfer agents, plasticizers, softeners, and surfactants, to the extent that they do not impair the effects of the present invention. Such additives can be used individually or in combination of two or more.

[0286] The haze of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of appearance characteristics, transparency, and optical properties, it is preferably 1% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. In this specification, the haze of the adhesive layer can be measured, for example, using a haze meter in accordance with JIS K 7136.

[0287] The visible light transmittance of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of appearance characteristics, transparency, and optical properties, it is preferably 90% or more, more preferably 90.5% or more, and even more preferably 91% or more. In this specification, the visible light transmittance of the adhesive layer can be measured, for example, using a haze meter in accordance with JIS K 7361-1. The above visible light transmittance is the transmittance of light (visible light) with a wavelength of 400 to 780 nm.

[0288] The thickness of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of obtaining sufficient adhesive reliability, it is preferably 12 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and particularly preferably 25 μm or more. A thickness of 12 μm or more is preferable because the adhesive layer can sufficiently follow the shrinkage or expansion under the usage environment of the image display device of the present invention, suppressing lifting and peeling, and providing excellent step absorption. Furthermore, from the viewpoint of optical properties, the thickness is preferably 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less.

[0289] <Manufacturing of optical adhesive sheets> The optical adhesive sheet of the present invention can be prepared by laminating the adhesive layer of the present invention onto the first surface of the substrate of the present invention.

[0290] The method for laminating the adhesive layer of the present invention onto the first surface of the substrate of the present invention is not particularly limited. For example, the adhesive composition may be applied to a release liner and the resulting adhesive composition layer may be dried and cured. Alternatively, the adhesive composition may be applied to a release liner and the resulting adhesive composition layer may be cured by irradiating it with active energy rays to form a sheet-like adhesive layer on the release liner, and the adhesive layer may be bonded to the first surface of the substrate of the present invention. Furthermore, if necessary, heating and drying may be performed. When curing by irradiation with active energy rays, it is preferable to attach a release liner to the surface of the coating film and irradiate it with active energy rays while the adhesive composition is sandwiched between the two release liners to prevent polymerization inhibition by oxygen.

[0291] Another method for laminating the adhesive layer of the present invention onto the first surface of the substrate of the present invention is, for example, to apply the adhesive composition to the first surface of the substrate of the present invention and dry and cure the resulting adhesive composition layer, or to apply the adhesive composition to the first surface of the substrate of the present invention and cure the resulting adhesive composition layer by irradiating it with active energy rays. Furthermore, if necessary, heating and drying may be performed. When curing by irradiation with active energy rays, it is preferable to attach a release liner to the surface of the coating film and irradiate it with active energy rays while the adhesive composition is sandwiched between the substrate of the present invention and the release liner, thereby preventing polymerization inhibition by oxygen.

[0292] Prior to irradiation with active energy rays, the sheet-like coating film may be heated for purposes such as solvent removal. If solvent removal by heating is performed, it is preferable to do so before attaching the release liner.

[0293] Examples of the active energy rays mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. Furthermore, there are no particular limitations on the irradiation energy, irradiation time, or irradiation method of the active energy rays.

[0294] The above adhesive compositions can be prepared by known or conventional methods. For example, a solvent-type acrylic adhesive composition can be prepared by mixing a liquid antistatic agent and, if necessary, an additive (e.g., an ultraviolet absorber) with a solution containing the above acrylic polymer. For example, an active energy ray-curable acrylic adhesive composition can be prepared by mixing a mixture of the above acrylic monomers or a partial polymer thereof with a liquid antistatic agent and, if necessary, an additive (e.g., an ultraviolet absorber).

[0295] Furthermore, known coating methods may be used for applying (coating) the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

[0296] In particular, when forming an adhesive layer with an active energy ray-curable adhesive composition, it is preferable that the active energy ray-curable adhesive composition contains a photopolymerization initiator. Furthermore, if the active energy ray-curable adhesive composition contains an ultraviolet absorber, it is preferable that it contains at least a photopolymerization initiator having absorption properties over a wide wavelength range. For example, it is preferable to contain at least a photopolymerization initiator that has absorption properties not only for ultraviolet light but also for visible light. This is because there is a concern that curing by active energy rays may be inhibited by the action of the ultraviolet absorber, and if a photopolymerization initiator having absorption properties over a wide wavelength range is included, it becomes easier to obtain high photocurability in the adhesive composition.

[0297] <Antistatic layer> The optical adhesive sheet of the present invention may have an antistatic layer on the surface or between any layers. The optical adhesive sheet of the present invention is preferable because having an antistatic layer can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel. Preferably, the antistatic layer is formed between the substrate of the present invention and the adhesive layer of the present invention.

[0298] The antistatic layer is not particularly limited, but for example, it is an antistatic layer formed by coating a conductive coating liquid containing a conductive polymer onto a peeling liner. Specifically, for example, it is an antistatic layer formed by coating a conductive coating liquid containing a conductive polymer onto the first surface of the substrate of the present invention. Specific coating methods include roll coating, bar coating, and gravure coating.

[0299] Examples of the conductive polymer include conductive polymers in which polyanions are doped into π-conjugated conductive polymers. Examples of π-conjugated conductive polymers include chain-like conductive polymers such as polythiophene, polypyrrole, polyaniline, and polyacetylene. Examples of polyanions include polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, ethyl polyacrylate sulfonic acid, and polymethacrylate.

[0300] The thickness of the antistatic layer is preferably 1 nm to 1000 nm, and more preferably 5 nm to 900 nm. The antistatic layer may consist of only one layer or two or more layers.

[0301] <Removable Liner> In the optical adhesive sheet of the present invention, the surface of the adhesive layer of the present invention (the adhesive surface of the adhesive layer of the present invention) may be protected by a release liner until use. The release liner is used as a protective material for the adhesive layer and is peeled off when the optical adhesive sheet of the present invention is attached to a substrate.

[0302] As the above-mentioned release liner, conventional release paper can be used. Specifically, for example, in addition to a substrate having a release treatment layer with a release treatment agent on at least one surface, low-adhesion substrates made of fluorine-based polymers (e.g., polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.) or low-adhesion substrates made of non-polar polymers (e.g., polyethylene, polypropylene, and other olefin resins) can be used.

[0303] As the above-mentioned peel-off liner, for example, a peel-off liner having a release treatment layer formed on at least one surface of the peel-off liner substrate can be suitably used. Examples of such peel-off liner substrates include plastic substrate films (synthetic resin films) such as polyester film (polyethylene terephthalate film, etc.), olefin resin film (polyethylene film, polypropylene film, etc.), polyvinyl chloride film, polyimide film, polyamide film (nylon film), and rayon film, as well as paper (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, topcoat paper, etc.), and composites of these made by laminating or co-extrusion (2-3 layer composites).

[0304] The release agent constituting the above-mentioned release layer is not particularly limited, but for example, silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, etc., can be used. The release agent can be used alone or in combination of two or more types.

[0305] The thickness of the release liner is not particularly limited and can be appropriately selected from the range of 5 to 100 μm.

[0306] The above-mentioned peel-off liner may have an antistatic layer formed on at least one surface of the substrate for the peel-off liner in order to prevent damage to the adherend such as an image display panel. The antistatic layer may be formed on one surface of the peel-off liner (the peel-off treated surface or the untreated surface), or on both surfaces of the peel-off liner (the peel-off treated surface and the untreated surface).

[0307] The antistatic layer is not particularly limited, but for example, it is an antistatic layer formed by coating a conductive coating liquid containing a conductive polymer onto a peeling liner. Specifically, for example, it is an antistatic layer formed by coating a conductive coating liquid containing a conductive polymer onto a peeling liner (the peeled surface and / or the untreated surface). Specific coating methods include roll coating, bar coating, and gravure coating.

[0308] As the conductive polymer, the same conductive polymer that constitutes the antistatic layer of the optical adhesive sheet of the present invention can be used.

[0309] The thickness of the antistatic layer is preferably 1 nm to 1000 nm, and more preferably 5 nm to 900 nm. The antistatic layer may consist of only one layer or two or more layers.

[0310] <Surface protective film> In the optical adhesive sheet of the present invention, the second surface of the substrate of the present invention may be protected by a surface protective film. The surface protective film is used as a protective material for the second surface of the substrate of the present invention during the manufacturing and transportation of the optical adhesive sheet of the present invention and the image display device of the present invention.

[0311] Examples of materials for forming the surface protective film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Preferably, it is an ester resin (particularly polyethylene terephthalate resin).

[0312] The thickness of the surface protective film is typically 20 μm to 250 μm, and preferably 30 μm to 150 μm.

[0313] The surface protective film is peelably bonded to the second surface of the substrate of the present invention via any suitable adhesive. Preferably, a surface protective film with an adhesive layer is formed and this is bonded to the second surface of the substrate of the optical adhesive sheet of the present invention. Examples of adhesives used for laminating the surface protective film include adhesive compositions in which an acrylic resin, styrene resin, silicone resin, etc., is used as the base resin, and a crosslinking agent selected from isocyanate compounds, epoxy compounds, aziridine compounds, etc., and a silane coupling agent are blended into this base resin. The thickness of the adhesive layer is usually 1 μm to 60 μm, preferably 3 μm to 30 μm. If the adhesive layer is too thin, problems such as reduced tackiness and increased susceptibility to air bubbles may occur, and if it is too thick, problems such as the adhesive overflowing may occur. From the viewpoint of chemical resistance and adhesion, acrylic adhesives are preferably used.

[0314] <Image display device> The image display device of the present invention has a laminated structure in which the optical adhesive sheet of the present invention and an image display panel are laminated. In Figure 3, the image display device 20 has the image display panel 4 laminated in the adhesive layer 1 of the optical adhesive sheet 10B.

[0315] The image display device of the present invention is preferable because, having the optical adhesive sheet of the present invention in a laminated structure, it can suppress the generation of static electricity when peeling the adhesive sheet from the image display panel for rework in the event of poor adhesion to the image display panel, thereby suppressing damage to the image display panel. Furthermore, it is preferable because, without impairing the adhesive properties of the adhesive layer of the invention, an excellent antistatic effect can be imparted to the adhesive layer of the invention, improving the adhesion between the adhesive layer of the invention and the substrate of the invention, and resulting in excellent thermal shock resistance. Moreover, it is preferable because the adhesive layer of the present invention maintains an excellent antistatic effect even in harsh environments such as thermal shock, and when a malfunction such as non-illumination of a light-emitting element occurs in the operating environment of the image display device, the generation of static electricity when peeling the adhesive sheet from the image display panel for repair can be suppressed. Furthermore, the increase in haze, shrinkage, or expansion of the optical adhesive sheet of the present invention due to thermal shock in the operating environment can be suppressed, and transparency can be maintained without change. In addition, the adhesive layer of the present invention follows the shrinkage or expansion of the image display device sufficiently, making it less prone to lifting or peeling. Furthermore, if the image display panel has uneven surfaces such as wiring, the adhesive layer of the present invention can adequately follow these uneven surfaces and fill them without leaving any air bubbles, thus exhibiting excellent surface absorption properties.

[0316] The aforementioned image display panel is not particularly limited, but examples include liquid crystal image display panels, self-emissive image display panels (e.g., organic EL (electroluminescent) image display panels, LED image display panels), etc.

[0317] The image display panel is formed by arranging RGB elements alternately, and it is preferable that the spaces between the RGB elements are filled with a black matrix (BM) in order to improve contrast.

[0318] The image display device of the present invention may include optical adhesive sheets and other optical components besides the image display panel of the present invention on its surface or between any layers. The optical components are not particularly limited, but examples include polarizing plates, phase difference plates, anti-reflective films, viewing angle adjustment films, and optical compensation films. The optical components also include components that serve a decorative or protective role while maintaining the visibility of the image display device or input device (such as design films, decorative films, and surface protection plates).

[0319] The image display device of the present invention can be manufactured by bonding the image display panel with the adhesive layer of the optical adhesive sheet of the present invention.

[0320] Specifically, the image display panel and the optical adhesive sheet of the present invention can be bonded together by lamination under heating and / or pressure. After lamination under heating and / or pressure, curing may be performed by irradiation with active energy rays. Irradiation with active energy rays can be performed in the same manner as the formation of the adhesive layer of the present invention.

[0321] <Tiling Display> The tiling display of the present invention is formed by arranging multiple image display devices of the present invention side by side. In Figure 4, the tiling display 30 is formed by arranging nine image display devices 20 (the stacked structure is not shown) in a 3x3 arrangement on a support substrate 31 in a tile-like manner, with the image display devices 20 touching each other through gaps 32. As the support substrate, a glass plate or plastic film similar to the substrate of the present invention can be used.

[0322] The image display device of the present invention suppresses shrinkage or expansion under the operating environment, thus reducing gaps and overlaps between multiple image display devices in the tiling display of the present invention, making gaps less noticeable and maintaining a good appearance. Furthermore, shrinkage or expansion is minimal, and transparency can be maintained without change. In addition, the adhesive layer of the present invention can adequately follow the shrinkage or expansion of the image display device, preventing problems caused by lifting or peeling.

[0323] Furthermore, in the tiling display of the present invention, it is preferable that the second surface of the substrate of the present invention is treated with an anti-reflective coating and / or an anti-glare coating, as this can prevent reflections caused by metal wiring, ITO wiring, etc., arranged on the substrate of the image display device of the present invention. It is also preferable that the gaps between the image display devices of the present invention become less visible in the tiling display.

[0324] The tiling display of the present invention may include components other than the image display device and the support substrate of the present invention. Such components are not particularly limited, but include backlights, touch sensors, and the like.

[0325] The tiling display of the present invention can be manufactured by arranging a plurality of the image display devices of the present invention without gaps on the support substrate and fixing them in place by sealing the outermost surface with glass. [Examples]

[0326] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0327] <Example 1> [Preparation of (meth)acrylic polymer solution 1] In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and 234 parts by mass of ethyl acetate were charged. Nitrogen gas was introduced while gently stirring, and the polymerization reaction was carried out for 6 hours while maintaining the temperature of the liquid in the flask at around 65°C to prepare (meth)acrylic polymer solution 1 (30% by mass). The weight-average molecular weight (Mw) of the (meth)acrylic polymer was 600,000, the molecular weight distribution (Mw / Mn) was 4.0, and the glass transition temperature (Tg) was -47°C.

[0328] [Preparation of acrylic adhesive composition 1] The (meth)acrylic polymer solution 1 (30% by mass) was diluted to 20% by mass with ethyl acetate. 500 parts by mass (100 parts by mass) of this solution were mixed and stirred to prepare acrylic adhesive composition 1 (acrylic adhesive solution). The mixture was then mixed and stirred.

[0329] [Preparation of adhesive sheet 1] The acrylic adhesive composition 1 was applied to the surface of a 75 μm thick polyethylene terephthalate film (PET film, transparent substrate, release liner) treated with a silicone release agent, air-dried for 3 minutes, and then heated at 145°C for 90 seconds to form an adhesive layer 1 with a thickness of 50 μm. Next, the non-anti-glare layer side of an anti-glare film (manufactured by DNP Corporation, product name "DSG23", PET film) with an anti-glare layer formed on one side was laminated to the surface of the adhesive layer 1 to obtain an adhesive sheet 1 consisting of an anti-glare film, adhesive layer 1, and release liner.

[0330] <Example 2> [Preparation of Acrylic Adhesive Composition 2] 556 parts by mass (100 parts by mass) of (meth)acrylic polymer solution 2 (manufactured by Soken Chemical Co., Ltd., trade name "SK Dyne 2137KH", copolymer of 99 parts by mass of butyl acrylate (BA) and 1 part by mass of 4-hydroxybutyl acrylate (HBA), 18% by mass), and 0.27 parts by mass (solids) of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D110N", trimethylolpropane xylylene diisocyanate) After adding 0.2 parts by mass of a peroxide-based crosslinking agent (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Nipper BMT", benzoyl peroxide), and 3 parts by mass of a liquid antistatic agent (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., trade name "MTOATFSI", trioctylmethylammonium bis(trifluoromethanesulfonyl)imide), the mixture was mixed and stirred to prepare acrylic adhesive composition 2. [Preparation of adhesive sheet 2] An adhesive sheet 1 comprising an anti-glare film / adhesive layer 1 / release liner was obtained in the same manner as in Example 1, except that the acrylic adhesive composition 2 was used.

[0331] <Example 3> [Preparation of acrylic adhesive composition 3] As monomer components for forming a prepolymer, 67 parts by mass of butyl acrylate (BA), 14 parts by mass of cyclohexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #155"), and 19 parts by mass of 4-hydroxybutyl acrylate (4HBA), along with 0.09 parts by mass of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad 184") and 0.09 parts by mass of another photopolymerization initiator (manufactured by BASF, trade name "Omnirad 651") were blended and polymerized by irradiation with ultraviolet light to obtain a prepolymer composition. To 100 parts by weight of the above prepolymer composition, 3 parts by mass of a liquid antistatic agent (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., trade name "MTOATFSI", trioctylmethylammonium bis(trifluoromethanesulfonyl)imide) was added, and these were uniformly mixed to prepare acrylic adhesive composition 3.

[0332] (Preparation of adhesive layer 3) A 75 μm thick polyethylene terephthalate (PET) film (Mitsubishi Chemical's "Diafoil MRF75") with a silicone-based release layer on its surface was used as a base material (also serving as a heavy-duty release liner). The above-mentioned acrylic adhesive composition 3 was applied to the release layer of the base material to a thickness of 50 μm to form a coating layer. On this coating layer, a release layer of a 75 μm thick PET film (Mitsubishi Chemical's "Diafoil MRE75") with one side treated with silicone release treatment was laminated as a cover sheet (also serving as a light-duty release liner). An irradiation intensity of 5 mW / cm² was applied to this laminate from the cover sheet side at the irradiation surface directly beneath the lamp. 2 Using a black light positioned to achieve this, ultraviolet light was irradiated to perform photocuring, resulting in an adhesive layer 3 with a thickness of 50 μm.

[0333] [Preparation of adhesive sheet 3] One of the release liners was peeled off from the adhesive layer 3 obtained above, and the non-anti-glare layer side of an anti-glare film (manufactured by DNP Corporation, product name "DSG23", PET film) with an anti-glare layer formed on one side was laminated to the exposed adhesive surface to obtain an adhesive sheet 3 consisting of an anti-glare film, adhesive layer 3, and release liner.

[0334] <Example 4> An adhesive sheet 4 consisting of an anti-glare film, an adhesive layer 4, and a release liner was obtained in the same manner as in Example 3, except that 3 parts by mass of 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, trade name "IL220" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., was used as a liquid antistatic agent.

[0335] <Example 5> An adhesive sheet 5 consisting of an anti-glare film, an adhesive layer 5, and a release liner was obtained in the same manner as in Example 3, except that 3 parts by mass of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, product name "CIL612" manufactured by Nippon Carlit Co., Ltd., was used as a liquid antistatic agent.

[0336] <Example 6> An adhesive sheet 6 consisting of an anti-glare film, an adhesive layer 6, and a release liner was obtained in the same manner as in Example 1, except that 2 parts by mass of 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, product name "CIL312" manufactured by Nippon Carlit Co., Ltd., was used as a liquid antistatic agent.

[0337] <Example 7> An adhesive sheet 7 consisting of an anti-glare film, an adhesive layer 7, and a release liner was obtained in the same manner as in Example 1, except that 5 parts by mass of 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, product name "CIL312" manufactured by Nippon Carlit Co., Ltd., was used as a liquid antistatic agent.

[0338] <Example 8> An adhesive sheet 8 consisting of an anti-glare film / adhesive layer 8 / release liner was obtained in the same manner as in Example 1, except that 10 parts by mass of 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, product name "CIL312" manufactured by Nippon Carlit Co., Ltd., was used as a liquid antistatic agent.

[0339] <Comparative Example 1> An adhesive sheet 9 consisting of an anti-glare film, an adhesive layer 9, and a release liner was obtained in the same manner as in Example 1, except that 0.1 parts by mass of 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, product name "CIL312" manufactured by Nippon Carlit Co., Ltd., was used as a liquid antistatic agent.

[0340] <Comparative Example 2> An adhesive sheet 10 consisting of an anti-glare film, an adhesive layer 10, and a release liner was obtained in the same manner as in Example 1, except that 3 parts by mass of lithium bis(trifluoromethanesulfonyl)imide, product name "LiTFSI" manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., was used as a solid antistatic agent.

[0341] <Comparative Example 3> An adhesive sheet 11 consisting of an anti-glare film / adhesive layer 11 / release liner was obtained in the same manner as in Example 3, except that 3 parts by mass of 1-ethyl-3-methylimidazolium bis(nonafluorobutylsulfonyl)imide, product name "EMIN441" manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., was used as a liquid antistatic agent.

[0342] (evaluation) The adhesive sheets obtained in the above examples and comparative examples were used for the following evaluations. The evaluation method is shown below. The results are shown in Table 2.

[0343] (1) Measurement of surface resistance The release liner was peeled off the adhesive sheet obtained in the above examples and comparative examples. Under conditions of a temperature of 23°C and a relative humidity of 50%, the surface resistance was measured using a resistivity meter (TREK Model 152-1) with a probe (TREK Model 152P-2P) in contact with the adhesive surface, under conditions of an applied voltage of 100V and a voltage application time of 10 seconds.

[0344] (2) Measurement of surface resistance after thermal shock test After removing the adhesive sheet from the thermal shock test described below, it was left in an environment of 23°C and 50% relative humidity for more than 2 hours. Using a resistivity meter (TREK Model 152-1), the surface resistance was measured by contacting the probe (TREK Model 152P-2P) with the adhesive surface from which the release liner had been removed, under the conditions of an applied voltage of 100V and a voltage application time of 10 seconds. • Thermal shock test The adhesive sheets obtained in the examples and comparative examples were subjected to thermal shock using a thermal shock tester for 200 cycles, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes. The absolute difference in surface resistance values ​​of the adhesive layer before and after the thermal shock test was calculated according to the following formula. |Log 10 B-Log 10 A| A: Surface resistance value before thermal shock test B: Surface resistance value after thermal shock test

[0345] (3) Measurement of the hardness of the adhesive layer by nanoindentation method For the adhesive layers of the examples and comparative examples, pieces approximately 1 cm square were cut out and fixed to a support (slide glass manufactured by Matsunami Glass Industry Co., Ltd.) to serve as samples for nanoindentation measurement. Nanoindentation measurements were performed under the following conditions, and load-displacement curves were obtained. • Nanoindentation measurement conditions Equipment: Triboindenter manufactured by Hysitron Inc. Indenter used: Berkovich (triangular pyramid) Measurement method: Single indentation measurement Measurement temperature: room temperature Indentation depth: 100nm

[0346] Hardness H is the load applied when the indenter is pressed down to the above-mentioned indentation depth (maximum load P). max The following formula (1) was used to calculate the contact area between the indenter and the sample (contact projected area Ac) at that time.

number

[0347] (4) Storage modulus of the adhesive layer and glass transition temperature The release liner was peeled off from the adhesive layer obtained in each example and comparative example, and multiple adhesive layers were laminated to prepare a test sample with a thickness of approximately 2 mm. This test sample was punched out into a 7.9 mm diameter disc shape, sandwiched between parallel plates, and dynamic viscoelasticity measurements were performed using the "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific under the following conditions. From the measurement results, the storage modulus G' at 25°C and 85°C was read. The temperature at which tanδ was maximum was defined as the glass transition temperature of the adhesive layer. (Measurement conditions) Transformation mode: Twist Measurement frequency: 1Hz Measurement temperature: -70℃~150℃

[0348] (5) 300% tensile residual stress value of the adhesive layer The adhesive layers obtained in each example and comparative example were cut to a size of 40 mm x 40 mm. After peeling off the release liner from one side, the pieces were folded once so that the adhesive sides were bonded together. The release liner from the other side was peeled off again, and the adhesive sides were bonded together once more to create adhesive layer samples of approximately 10 mm x 40 mm in size and approximately 400 μm in thickness. The above adhesive layer samples were set on a tensile testing machine with the chuck distance set to 20 mm, and pulled to 60 mm (300%) at a tensile speed of 200 mm / min (the chuck distance after pulling was 80 mm). The samples were held in place for 300 seconds at the 60 mm pulled position, and the stress value thereafter was measured. The "300% tensile residual stress value" was calculated using the following formula. 300% tensile residual stress value (N / cm 2 ) = Stress value after fixing and holding for 300 seconds (N) / (4 × adhesive sheet thickness (mm) / 10)

[0349] (6) Hayes The adhesive sheets obtained in each example and comparative example were measured at room temperature (23°C) using a haze measuring device (HR-100, manufactured by Murakami Color Research Institute). Three measurements were taken, and the average value was used as the measured value.

[0350] (7) Haze after thermal shock test The adhesive sheets obtained in each example and comparative example were subjected to the thermal shock test described above, and then measured at room temperature (23°C) using a haze measuring device (HR-100, manufactured by Murakami Color Research Institute). Three measurements were repeated, and the average value was taken as the measured value. The difference in haze before and after the thermal shock test (haze after thermal shock test - haze before thermal shock test) was calculated.

[0351] (8)Visible light transmittance The adhesive sheets obtained in each example and comparative example were measured at room temperature (23°C) using a haze measuring device (HR-100, manufactured by Murakami Color Research Institute). Three measurements were taken, and the average value was used as the measured value.

[0352] (9)L * a * b * Color system The adhesive sheets obtained in each example and comparative example were attached to a glass slide (product name "MICRO SLIDE GLASS", white polished, No. 2, thickness: 1.0~1.2 mm, manufactured by Matsunami Glass Co., Ltd.) to create test specimens. When attaching the adhesive sheets, a hand roller was used to prevent fingerprints and other dirt from adhering to the surface, and to avoid trapping foreign matter or air bubbles. L of the above test piece * value, b * Value and a * The values ​​were measured using a simple spectrophotometer (product name "DOT-3C," manufactured by Murakami Color Technology Laboratory Co., Ltd.). The measurement was performed by shining light onto the adhesive sheet surface of the test specimen. L * value, b * Value and a * The values ​​were determined in accordance with JIS Z 8781-4 (2013). b after thermal shock test * Regarding this, the test specimens prepared as described above were subjected to the thermal shock test, left in an environment of 23°C and 50% relative humidity for more than 2 hours, and measured using a simple spectrophotometer (product name "DOT-3C", manufactured by Murakami Color Technology Laboratory Co., Ltd.). b after the thermal shock test * Therefore, b before the thermal shock test * Subtracting this value gives b after the thermal shock test. * The difference (Δb) * )

[0353] (10) Adhesion strength and peel charge to Alyl plate [Method for measuring adhesive strength to acrylic sheets] As the adherend, an acrylic sheet measuring 70 mm in width and 100 mm in length (manufactured by Mitsubishi Rayon Co., Ltd., product name "Acrylite", thickness: 1 mm) was prepared. The adhesive sheets obtained in each example and comparative example were cut to a size of 25 mm in width and 100 mm in length, and the adhesive side was pressed onto the acrylic sheet at a pressure of 0.25 MPa and a speed of 0.3 m / min. After being left attached in an environment of 23°C and 50% RH for 30 minutes, the adhesive sheet was peeled off the acrylic sheet using a universal tensile testing machine under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180°, and the adhesive strength [N / 25 mm] at this time was measured.

[0354] [Method for measuring the amount of electrostatic charge due to delamination] The adhesive sheets obtained in each example and comparative example were cut to a size of 25 mm in width and 80 mm in length. After peeling off the release liner, they were attached to an acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd., product name "Acrylite", thickness: 1 mm, width: 25 mm, length: 70 mm) that had been pre-statically discharged. The sheets were then pressed down with a hand roller so that one end of the adhesive sheet extended 10 mm beyond the edge of the acrylic plate. The sample was left in an environment of 23°C and 50%RH for one day, and then set on a sample fixing stand 20mm high. The end of the adhesive sheet, which extended 10mm beyond the acrylic plate, was fixed to an automatic winding machine, and the sheet was peeled off at a peeling angle of 150° and a peeling speed of 5m / min. The potential of the surface of the adherend (acrylic plate) generated at this time was measured using a potential measuring instrument (Kasuga Electric Co., Ltd., model "KSD-0103") fixed at a height of 100mm from the center of the acrylic plate. The measurement was performed in an environment of 23°C and 50%RH.

[0355] (11) Evaluation of adhesion to the substrate (step absorption ability) The adhesion (adhesion absorption) of the adhesive sheets obtained in each example and comparative example was investigated using so-called printed glass. The surface of the printed glass used had a printed layer pattern formed on it that created a printed step of 15 μm relative to the glass surface. The adhesive sheet was then bonded to the printed pattern surface of such printed glass at room temperature using a hand roller. Adhesion was evaluated as good (○) if no lift of 1 mm or more in width occurred along the edge of the printed pattern on the glass surface (the printed step portion) of the adhesive sheet bonded to the printed glass, and as poor (×) if such lift of 1 mm or more in width occurred.

[0356] (12) Evaluation of voids after thermal shock testing Similar to the adhesion evaluation described above, test specimens were prepared by attaching an adhesive sheet to printed glass using a hand roller. After subjecting the prepared test specimens to the thermal shock test described above, they were left in an environment of 23°C and 50% relative humidity for more than 2 hours, and visual inspection was performed to check for gaps in the printed step areas. Adhesion was evaluated as good (○) if no lifting of 1 mm or more in width occurred along the edges of the printed pattern on the glass surface (the printed step areas) of the adhesive sheet attached to the printed glass, and as poor (×) if such lifting of 1 mm or more in width occurred.

[0357] [Table 2]

[0358] Variations of the present invention are listed below. [Note 1] An optical adhesive sheet having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer laminated on the first surface of the substrate, The adhesive layer contains a liquid antistatic agent, The surface resistance value of the adhesive layer is 10 10 It is less than Ω, An optical adhesive sheet characterized by having a haze of 1% or less after the thermal shock test described below. • Thermal shock test The optical adhesive sheet is subjected to thermal shock for 200 cycles using a thermal shock tester, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes. [Note 2] The optical adhesive sheet described in Note 1, wherein the antistatic agent is an ionic liquid. [Note 3] The optical adhesive sheet described in Note 2, wherein the ionic liquid includes an anion portion with 10 or fewer fluorine atoms. [Note 4] The optical adhesive sheet described in any one of Notes 1 to 3, wherein the difference in haze of the optical adhesive sheet before and after the thermal shock test (haze of the optical adhesive sheet after the thermal shock test - haze of the optical adhesive sheet before the thermal shock test) is 2% or less. [Note 5] The optical adhesive sheet described in any one of Notes 1 to 4, wherein the absolute value of the difference in surface resistance values ​​of the adhesive layer before and after the thermal shock test, as shown by the following formula, is 1 log Ω or less. |Log 10 B-Log 10 A| A: Surface resistance value before thermal shock test B: Surface resistance value after thermal shock test [Note 6] The optical adhesive sheet according to any one of Notes 1 to 5, wherein the second surface of the substrate is treated with an anti-reflective coating and / or an anti-glare coating. [Note 7] The optical adhesive sheet according to any one of Notes 1 to 6, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer. [Note 8] An image display device comprising an optical adhesive sheet described in any one of Notes 1 to 7 and an image display panel laminated together. [Note 9] A tiling display consisting of multiple image display devices as described in Note 8. [Explanation of Symbols]

[0359] 10A, 10B Optical Adhesive Sheets 1 Base material 1a First surface of the substrate 1b Second surface of the substrate 2. Adhesive layer 3. Anti-reflective and / or anti-glare treatment 20 Image display devices 4 Image display panel 30 tiling displays 31 Support substrate

Claims

1. An optical adhesive sheet having a laminated structure comprising a substrate having a first surface and a second surface, and an adhesive layer laminated on the first surface of the substrate, The adhesive constituting the aforementioned adhesive layer is an acrylic adhesive layer containing an acrylic polymer as the base polymer. The content of the acrylic polymer in the adhesive layer is 50% by weight or more based on 100% by weight of the total weight of the adhesive layer. The adhesive layer contains a liquid antistatic agent, The surface resistance value of the adhesive layer is 10 10 It is less than Ω, The haze after the thermal shock test described below was less than 1%. An optical adhesive sheet characterized in that the absolute value of the difference in surface resistance values ​​of the adhesive layer before and after the thermal shock test described below, as shown by the following formula, is 1 log Ω or less. |Log 10 B-Log 10 A| A: Surface resistance value before thermal shock test B: Surface resistance value after thermal shock test • Thermal shock test The optical adhesive sheet is subjected to thermal shock using a thermal shock tester for 200 cycles, with each cycle consisting of exposure to a -40°C atmosphere for 30 minutes, followed by exposure to an 80°C atmosphere for 30 minutes.

2. The optical adhesive sheet according to claim 1, wherein the antistatic agent is an ionic liquid.

3. The optical adhesive sheet according to claim 2, wherein the ionic liquid includes an anion portion having 10 or fewer fluorine atoms.

4. The optical adhesive sheet according to any one of claims 1 to 3, wherein the difference in haze of the optical adhesive sheet before and after the thermal shock test (haze of the optical adhesive sheet after the thermal shock test - haze of the optical adhesive sheet before the thermal shock test) is 2% or less.

5. The optical adhesive sheet according to any one of claims 1 to 4, wherein the second surface of the substrate is treated with an anti-reflective coating and / or an anti-glare coating.

6. An image display device comprising an optical adhesive sheet according to any one of claims 1 to 5 and an image display panel laminated together.

7. A tiling display comprising multiple image display devices as described in claim 6.

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