Optical adhesive tape

Abstract

The present invention aims to provide an optical adhesive tape for a tiling display in which a plurality of image display devices are arranged in a tiled manner, such that the gaps between the plurality of image display devices are difficult to notice even under usage conditions, transparency can be maintained, and a good appearance can be maintained. The optical adhesive tape (10A) of the present invention has a laminated structure comprising a substrate (1) having a first surface (1a) and a second surface (1b), and an adhesive layer (2) laminated on the first surface (1a) of the substrate (1). When the optical adhesive tape (10A) is heated for 500 hours in an environment of 60°C and 90% relative humidity, the average dimensional change rate in the width direction and the machine direction is within ±0.15%. When an adhesive area of ​​1 cm² of the adhesive layer (2) is bonded to a resin plate and tensile at 23°C in the shear direction at a tensile speed of 0.06 mm / min, the shear force is 20 N / cm² or less.

Description

Technology Field

[0001] The present invention relates to an optical adhesive tape. More specifically, it relates to an optical adhesive tape suitable for manufacturing a tiling display in which a plurality of image display devices are arranged in a tiled shape. Background Technology

[0002] With the advancement of high-definition displays such as 4K and 8K, the demand for larger screen image display devices is increasing. Furthermore, the use of large screen image display devices for signage, such as advertising displays and bulletin boards in outdoor areas and public facilities, is also progressing. However, manufacturing large screen image display devices results in a problem where the yield decreases and manufacturing costs increase. In order to manufacture large screen image display devices at a lower cost, tiling displays in which multiple image display devices are arranged in a tiled pattern are being considered (e.g., Patent Document 1). Prior art literature

[0003] Japanese Patent Publication No. 2017-161634 The problem to be solved

[0004] In tiling displays, it is necessary to make the gaps between multiple image display devices narrow (e.g., 100 μm or less) so that they are not visible. However, under usage conditions, the image display devices shrink or expand, causing small gaps or slight overlap of the image display devices, which makes the gaps visible, and also reduces transparency, resulting in poor appearance. In addition, there was a problem in that the adhesive layer bonding the optical components constituting the image display devices could not keep up with the shrinkage and expansion of the image display devices, causing lifting or delamination at the edges and poor appearance.

[0005] The present invention has been conceived based on the circumstances described above, and the objective of the present invention is to provide an optical adhesive tape for a tiling display in which a plurality of image display devices are arranged in a tiled manner, such that the gaps between the plurality of image display devices are difficult to notice even under usage conditions, transparency can be maintained, and a good appearance can be maintained. means of solving the problem

[0006] That is, the first aspect of the present invention provides an optical adhesive tape 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.

[0007] The optical adhesive tape of the first aspect of the present invention has an average dimensional change rate in the width direction and machine direction within ±0.15% when heated for 500 hours in an environment of 60°C and 90% relative humidity. The configuration in which the average dimensional change rate is within ±0.15% is suitable for a tiling display in which a plurality of image display devices, each having a laminated optical adhesive tape of the first aspect of the present invention, are arranged, in terms of suppressing shrinkage or expansion under the usage environment of the image display devices, suppressing the visibility of gaps between image display devices, maintaining a good appearance, having minimal shrinkage or expansion, and maintaining transparency without change. In terms of suppressing the visibility of gaps between image display devices, having minimal shrinkage or expansion, and maintaining transparency without change, the average dimensional change rate is preferably within ±0.1%, and may be within ±0.05%.

[0008] In the optical adhesive tape of the first aspect of the present invention, the adhesive area of ​​the adhesive layer is bonded to a resin plate, and the shear force when tensile in the shear direction at a tensile speed of 0.06 mm / min at 23°C is 20 N / cm² or less. In this specification, when the term "shear force" is used, unless otherwise specifically stated, it refers to "the shear force when the adhesive area of ​​the adhesive layer is bonded to a resin plate, and tensile in the shear direction at a tensile speed of 0.06 mm / min at 23°C."

[0009] The configuration in which the shear force of the adhesive layer is 20 N / cm² or less is desirable in that the adhesive layer can sufficiently follow shrinkage or expansion under the usage environment of an image display device laminated with the optical adhesive tape of the first aspect of the present invention, thereby suppressing lifting or peeling. In addition, it is also desirable in that when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or peeling of the optical adhesive tape of the first aspect of the present invention and to follow the step, the shear force of the adhesive layer is preferably 15 N / cm² or less, and may be 13 N / cm² or less.

[0010] The average dimensional change rate in the width direction and the machine direction when the optical adhesive tape of the first aspect of the present invention is heated for 500 hours in an environment of 60°C and 90% relative humidity is denoted as C[%], and

[0011] It is desirable to satisfy the following formula when the maximum curl amount is D [mm] when the adhesive layer of the above optical adhesive tape is bonded to a PET film with a thickness of 50 μm and the laminate, cut into 10 cm squares, is heated for 500 hours in an environment of 60°C and 90% relative humidity.

[0012] |C×D|≤3

[0013] · Maximum curl amount: Place the laminated body on a horizontal plane with the convex side of the curl facing downward, and the highest curvature among the four corners is defined as the maximum curl amount D [mm]. Place the laminated body on a horizontal plane with the PET film side facing downward and measure the maximum curl amount, and place the laminated body on a horizontal plane with the substrate side facing downward and measure the maximum curl amount, and mark it as -.

[0014] The configuration in which the absolute value |C×D| of the product of the above average dimensional change rate C[%] and the above maximum curl amount D[mm] is 3 or less is suitable in a tiling display in which a plurality of image display devices laminated with an optical adhesive tape of the first aspect of the present invention are arranged, in that it is difficult to perceive a change in the gap between the image display devices and the image display devices can be bonded to a film substrate with high precision. In that it is difficult to perceive a change in the gap between the image display devices and the image display devices can be bonded to a film substrate with high precision, the above |C×D| is preferably 2.5 or less, more preferably 2.4 or less, and may be 2.3 or less, or 2.2 or less.

[0015] In the optical adhesive tape of the first aspect of the present invention, it is preferable that the glass transition point (Tg) of the substrate be 60°C or higher. The configuration in which the glass transition point of the substrate is 60°C or higher is preferred in that the mechanical properties of the image display device are stable under the usage environment in a tiling display in which a plurality of image display devices, each having a laminated optical adhesive tape of the first aspect of the present invention, are arranged. From the perspective of the stability of the mechanical properties of the image display device, the glass transition point of the substrate may be 63°C or higher, or 65°C or higher.

[0016] In the optical adhesive tape of the first aspect of the present invention, it is preferable that the glass transition point (Tg) of the adhesive layer be -10°C or lower. The configuration in which the Tg of the adhesive layer is -10°C or lower is desirable in that the stress relaxation properties of the adhesive layer are maintained even under a low-temperature environment, so that the adhesive layer sufficiently follows shrinkage or expansion in the usage environment of an image display device in which the optical adhesive tape of the first aspect of the present invention is laminated, thereby suppressing lifting or delamination and ensuring sufficient adhesion to the substrate. In order to suppress lifting or delamination in the image display device and to ensure good adhesion to the substrate, the glass transition point of the adhesive layer is preferably -15°C or lower, and may be -20°C or lower.

[0017] It is preferable that the humidity expansion rate of the optical adhesive tape of the first aspect of the present invention be 0.1% or less when humidified from 30% relative humidity at 60°C to 60% relative humidity at 60°C. The configuration in which the humidity expansion rate is 0.1% or less is suitable for a tiling display in which a plurality of image display devices, each having a laminated optical adhesive tape of the first aspect of the present invention, are arranged, in terms of suppressing expansion caused by moisture absorption of the image display devices and suppressing the visibility of gaps between the image display devices, having minimal shrinkage or expansion, and maintaining transparency without change. From the perspective of suppressing expansion caused by moisture absorption of the image display devices, having minimal shrinkage or expansion, and maintaining transparency without change, the humidity expansion rate is preferably 0.08% or less, and may be 0.06% or less.

[0018] In the optical adhesive tape of the first aspect of the present invention, the humidity expansion coefficient of the substrate is 5×10 -5 It is preferable that it be / %RH or less. The humidity expansion coefficient of the above-described material is 5×10 -5The configuration described as having / %RH or less is suitable in that the dimensional stability of the above-described material with respect to changes in humidity is improved, and in a tiling display comprising a plurality of image display devices laminated with an optical adhesive tape according to the first aspect of the present invention, the shrinkage or expansion of the image display device under usage conditions is suppressed and the gaps between the image display devices are not noticeable, thereby maintaining a good appearance, and the shrinkage or expansion is minimal and transparency can be maintained without change. In terms of the dimensional stability of the above-described material, the shrinkage or expansion is minimal and transparency can be maintained without change, the humidity expansion coefficient of the above-described material is 3×10 -5 / %RH or less is desirable, and 2×10 -5 / %RH or less is acceptable.

[0019] In the optical adhesive tape of the first aspect of the present invention, it is preferable that the second surface of the substrate be treated with an anti-reflective and / or anti-glare treatment. The configuration in which the second surface of the substrate is treated with an anti-reflective and / or anti-glare treatment is desirable in that it can prevent reflection caused by metal wiring or ITO wiring, etc., disposed on the substrate of the image display device. Furthermore, in a tiling display in which a plurality of image display devices, each having a laminated optical adhesive tape of the first aspect of the present invention, are arranged, it is also desirable in that the gaps between the image display devices become difficult to see.

[0020] In the optical adhesive tape of the first aspect of the present invention, the adhesive layer is preferably an acrylic adhesive layer comprising an acrylic polymer. This configuration is suitable for adjusting the characteristics (particularly shear force) of the adhesive layer.

[0021] Additionally, a second aspect of the present invention provides an image display device in which an optical adhesive tape of the first aspect of the present invention and an image display panel are laminated. Additionally, a third aspect of the present invention provides a tiling display in which a plurality of image display devices of the second aspect of the present invention are arranged.

[0022] The image display device of the second aspect of the present invention can suppress shrinkage or expansion under usage conditions because it has the optical adhesive tape of the first aspect of the present invention in a laminated structure. Furthermore, even if the image display device of the second aspect of the present invention shrinks or expands to some extent, the adhesive layer sufficiently follows the shrinkage or expansion of the image display device, making it difficult for lifting or peeling to occur. Therefore, in the tiling display of the third aspect of the present invention, which is manufactured by arranging multiple image display devices of the second aspect of the present invention, the gaps between the image display devices are difficult to notice under usage conditions, and a good appearance can be maintained. Additionally, transparency can be maintained without change. Effects of the invention

[0023] By using the optical adhesive tape of the present invention in the manufacture of a tiling display in which multiple image display devices are arranged, shrinkage or expansion under the usage environment of the image display devices can be suppressed, so the gaps between the image display devices are difficult to notice and a good appearance can be maintained. In addition, transparency can be maintained without change. Furthermore, even if the image display devices expand or contract to some extent, lifting or peeling of the adhesive layer is unlikely to occur, so a high-performance tiling display can be manufactured efficiently. Brief explanation of the drawing

[0024] FIG. 1 is a schematic diagram illustrating one embodiment of the optical adhesive tape of the present invention. (a) is a cross-sectional view, and (b) is a top view. FIG. 2 is a schematic diagram (cross-sectional view) illustrating another embodiment of the optical adhesive tape of the present invention. FIG. 3 is a schematic diagram (cross-sectional view) illustrating one embodiment of the image display device of the present invention in which the optical adhesive tape of FIG. 2 is laminated. FIG. 4 is a schematic diagram (perspective view) illustrating one embodiment of the tiling display of the present invention. Figure 5 is a schematic diagram (perspective view) for explaining a shear test. Specific details for implementing the invention

[0025] A first aspect of the present invention provides an optical adhesive tape 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.

[0026] In this specification, the optical adhesive tape of the first aspect of the present invention may be referred to as the "optical adhesive tape of the present invention." Additionally, the substrate and the adhesive layer constituting the optical adhesive tape of the present invention may be referred to as the "substrate of the present invention" and the "adhesive layer of the present invention," respectively. Furthermore, the term "adhesive tape" includes the meaning of "adhesive sheet." That is, the optical adhesive tape of the present invention may be an adhesive sheet having a sheet-like form.

[0027] A second aspect of the present invention provides an image display device in which an optical adhesive tape of the first aspect of the present invention and an image display panel are laminated. 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" in this specification.

[0028] In addition, a third aspect of the present invention provides a tiling display in which a plurality of image display devices of the present invention are arranged. The tiling display of the third aspect of the present invention may be referred to as the "tiling display of the present invention" in this specification.

[0029] Hereinafter, embodiments of the optical adhesive tape of the present invention will be described in relation to the drawings, but the present invention is not limited thereto and is merely an example.

[0030] FIG. 1 is a schematic diagram illustrating one embodiment of the optical adhesive tape of the present invention. (a) is a cross-sectional view, and (b) is a top view.

[0031] In FIG. 1 (a), the optical adhesive tape (10A) has a laminated structure in which a substrate (1) and an adhesive layer (2) are laminated. The substrate (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 substrate (1).

[0032] In Fig. 1(b), the width direction (TD) and machine direction (MD) of the optical adhesive tape (10A) are determined to correspond to the width direction (TD) and machine direction (MD) of the substrate (1).

[0033] In FIG. 2, the optical adhesive tape (10B) has a laminated structure in which a substrate (1) and an adhesive layer (2) are laminated. The substrate (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 substrate (1). The second surface (1b) of the substrate (1) is treated with an anti-reflection treatment and / or an anti-glare treatment (3).

[0034] FIG. 3 is a schematic diagram (cross-sectional view) illustrating one embodiment of the image display device of the present invention. In FIG. 3, the image display device (20) has an image display panel (4) laminated on an adhesive layer (2) of an optical adhesive tape (10B).

[0035] FIG. 4 is a schematic diagram (perspective view) illustrating one embodiment of the tiling display of the present invention. In FIG. 4, the tiling display (30) is formed by arranging nine image display devices (20) (the stacked structure is omitted) in a 3×3 arrangement on a support substrate (31) in a tile-like manner, and the image display devices (20) are in contact with each other through a gap (32).

[0036] The following describes each component.

[0037] Optical adhesive tape

[0038] In the optical adhesive tape of the present invention, "optical" means being used for optical purposes, and more specifically, means being used in the manufacture of products (optical products) in which optical components are used. Examples of optical products include image display devices, input devices such as touch panels, etc., but they can be suitably used in the manufacture of liquid crystal image display devices, self-emissive image display devices (e.g., organic EL (electroluminescence) image display devices, LED image display devices), etc. In particular, the optical adhesive tape of the present invention is suitable for the manufacture of a tiling display in which a plurality of image display devices are arranged in a tiled shape.

[0039] The optical adhesive tape of the present invention is not particularly limited in shape 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 tape in which only one side is an adhesive surface, or a double-sided adhesive tape in which both sides are adhesive surfaces. Furthermore, when the optical adhesive tape of the present invention is a double-sided adhesive tape, the optical adhesive tape of the present invention may have a shape 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). When the optical adhesive tape of the present invention constitutes the outermost surface of an optical product, a single-sided adhesive tape is preferred, and when bonding adherends (optical members) to each other, a double-sided adhesive tape is preferred.

[0040] The optical adhesive tape of the present invention may, in addition to the substrate of the present invention and the adhesive layer of the present invention, have other layers, for example, 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 separator, a surface protection film, etc., between the surface or any other layers, to a extent that does not impair the effects of the present invention.

[0041] The optical adhesive tape of the present invention has an average dimensional change rate in the width direction and machine direction within ±0.15% when heated for 500 hours in an environment of 60°C and 90% relative humidity. The dimensional change rate in the width direction and machine direction is the percentage (%) of the change in dimensions after heating for 500 hours in an environment of 60°C and 90% relative humidity, with the respective initial dimensions in the width direction and machine direction set to 100%, and is calculated from the following formula.

[0042] Dimensional change rate (%) = [(Dimensions after heating for 500 hours in an environment of 60℃ and 90% relative humidity) - (Initial dimensions)] / (Initial dimensions) × 100

[0043] In the dimensional change rate (%), "+" indicates expansion and "-" indicates contraction. The average dimensional change rate in the width direction and the machine direction is the average value of the dimensional change rates in the width direction and the machine direction, and is calculated from the following formula.

[0044] Average dimensional change rate (%) = [(Dimensional change rate in width direction (%)) + (Dimensional change rate in machine direction (%))] / 2

[0045] In addition, the dimensions of the optical adhesive tape of the present invention are not particularly limited, but generally can be obtained by measuring the lengths of the ends in the width direction and the machine direction of the optical adhesive tape.

[0046] The configuration in which the above average dimensional change rate is within ±0.15% is suitable for the tiling display of the present invention in terms of suppressing shrinkage or expansion under the usage environment of the image display device of the present invention, suppressing the noticeableness of gaps between image display devices, maintaining a good appearance, having minimal shrinkage or expansion, and maintaining transparency without change. In terms of suppressing the noticeableness of gaps between image display devices, having minimal shrinkage or expansion, and maintaining transparency without change, the above average dimensional change rate is preferably within ±0.1%, and may be within ±0.05%.

[0047] The average dimensional change rate in the optical adhesive tape of the present invention can be specifically measured by the method of the example disclosed later. The average dimensional change rate in the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient or glass transition point of the substrate, the type of resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus or glass transition point, etc.

[0048] The average dimensional change rate in the width direction and machine direction when the optical adhesive tape of the present invention is heated for 500 hours in an environment of 60°C and 90% relative humidity is denoted as C[%], and

[0049] It is desirable to satisfy the following formula when the maximum curl amount is D [mm] when the adhesive layer of the above optical adhesive tape is bonded to a PET film with a thickness of 50 μm and the laminate, cut into 10 cm squares, is heated for 500 hours in an environment of 60°C and 90% relative humidity.

[0050] |C×D|≤3

[0051] · Maximum curl amount: Place the laminated body on a horizontal plane with the convex side of the curl facing downward, and the highest curvature among the four corners is defined as the maximum curl amount D [mm]. Place the laminated body on a horizontal plane with the PET film side facing downward and measure the maximum curl amount, and place the laminated body on a horizontal plane with the substrate side facing downward and measure the maximum curl amount, and mark it as -.

[0052] The configuration in which the absolute value |C×D| of the product of the above average dimensional change rate C[%] and the above maximum curl amount D[mm] is 3 or less is suitable in a tiling display in which a plurality of image display devices laminated with the optical adhesive tape of the present invention are arranged, in that it is difficult to see a change in the gap between the image display devices and the image display devices can be bonded to a film substrate with high precision. In that it is difficult to see a change in the gap between the image display devices and the image display devices can be bonded to a film substrate with high precision, the above |C×D| is preferably 2.5 or less, more preferably 2.4 or less, and may be 2.3 or less, or 2.2 or less.

[0053] The lower limit of the above |C×D| is not specifically limited, and while it is preferable for it to be lower, it may be 0.001 or higher.

[0054] The absolute value |D|[mm] of the maximum curl amount is not particularly limited, but in a tiling display in which a plurality of image display devices laminated with the optical adhesive tape of the present invention are arranged, it is preferable that the image display device be bonded to a film substrate with high precision by being 60 mm or less, more preferable that it be 55 mm or less, and even more preferable that it be 50 mm or less.

[0055] The lower limit of the above |D| is not specifically limited, and while it is preferable for it to be lower, it may be 0.1mm or more.

[0056] In the optical adhesive tape of the present invention, the above |C×D| and |D| can be specifically measured by the method of the example disclosed later. In the optical adhesive tape of the present invention, the above |C×D| and |D| can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient or glass transition point of the substrate, the type of resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus or glass transition point, etc.

[0057] It is preferable that the humidity expansion rate of the optical adhesive tape of the present invention be 0.1% or less when humidified from 30% relative humidity at 60°C to 60% relative humidity at 60°C. The configuration in which the humidity expansion rate is 0.1% or less is suitable for the tiling display of the present invention in terms of suppressing expansion caused by moisture absorption of the image display device of the present invention, suppressing the visibility of gaps between image display devices, minimizing shrinkage or expansion, and maintaining transparency without change. From the perspective of suppressing expansion caused by moisture absorption of the image display device of the present invention, minimizing shrinkage or expansion, and maintaining transparency without change, the humidity expansion rate is preferably 0.08% or less, and may be 0.06% or less.

[0058] The lower limit of the above humidity expansion rate is not specifically limited, and while it is preferable for it to be lower, it may be 0.0001% or higher.

[0059] The humidity expansion rate in the optical adhesive tape of the present invention can be specifically measured by the method of the example disclosed later. The humidity expansion rate in the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient or glass transition point of the substrate, the type of resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus or glass transition point, etc.

[0060] The ratio of the rate of change in dimensions in the machine direction to the rate of change in dimensions in the width direction (rate of change in dimensions in the machine direction / rate of change in dimensions in the width direction) when the optical adhesive tape of the present invention is heated for 500 hours in an environment of 60°C and 90% relative humidity is not particularly limited, but is preferably 0.5 or more and 2.0 or less. Since the said ratio is within this range, in the tiling display of the present invention, the difference between the rate of change in dimensions in the width direction and the machine direction under the usage environment of the image display device of the present invention is reduced, and the gap between image display devices is suppressed from being noticeable, thereby maintaining a good appearance, and shrinkage or expansion is minimal, and transparency is maintained without change. In terms of suppressing the gap between image display devices from being noticeable, shrinkage or expansion is minimal, and transparency is maintained without change, the said ratio is preferably 0.6 or more and 1.8 or less, and may be 0.7 or more and 1.5 or less.

[0061] The above ratio (ratio of change in dimensions in the machine direction / ratio of change in dimensions in the width direction) in the optical adhesive tape of the present invention can be adjusted by adjusting the type or thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient or glass transition point of the substrate, the manufacturing conditions of the substrate (e.g., temperature or speed of extrusion molding), the type of resin constituting the adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus or glass transition point, etc.

[0062] The haze of the optical adhesive tape of the present invention is not particularly limited, but is preferably 5% or more. The configuration in which the haze of the optical adhesive tape of the present invention is 5% or more is desirable in that it can prevent reflection caused by metal wiring or ITO wiring disposed on the substrate of the image display panel in the image display device of the present invention, and in that the gap between image display devices becomes difficult to see in the tiling display of the present invention, and is more preferably 6% or more, and may be 7% or more. The upper limit of the haze of the optical adhesive tape of the present invention is not particularly limited, but is preferably 50% or less from the perspective of visibility of the tiling display of the present invention, and may be 40% or less or 30% or less.

[0063] The haze of the optical adhesive tape of the present invention can be measured in accordance with JIS K 7136, and specifically, can be measured by the method described in the examples posted later. The haze of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, and by applying an anti-reflective treatment and / or an anti-glare treatment to the surface of the substrate.

[0064] The reflectance of the optical adhesive tape of the present invention is not particularly limited, but is preferably 5% or less. A configuration in which the reflectance of the optical adhesive tape of the present invention is 5% or less is desirable in that it prevents reflection caused by metal wiring or ITO wiring disposed on the substrate of an image display panel in the image display device of the present invention, and in that the gap between image display devices becomes difficult to see in the tiling display of the present invention, and is more preferably 3% or less, and may be 1.5% or less. The lower limit of the reflectance of the optical adhesive tape of the present invention is not particularly limited, but may be 0.1% or more, or 0.3% or more.

[0065] The reflectance of the optical adhesive tape of the present invention can be measured in accordance with JIS K7361-1, and specifically, can be measured by the method described in the examples listed below. The reflectance of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, and by applying an anti-reflective treatment and / or an anti-glare treatment to the surface of the substrate.

[0066] The total light transmittance of the optical adhesive tape of the present invention is not particularly limited, but is preferably 85% or higher. A configuration in which the total light transmittance of the optical adhesive tape of the present invention is 85% or higher is desirable in that excellent transparency or excellent appearance is obtained in the image display device of the present invention, and more preferably 88% or higher, and may be 90% or higher. The upper limit of the total light transmittance of the optical adhesive tape of the present invention is not particularly limited, but may be 95% or lower.

[0067] The total light transmittance of the optical adhesive tape of the present invention can be measured in accordance with JIS K7361-1. The total light transmittance of the optical adhesive tape of the present invention can be adjusted by the type or thickness of the resin constituting the substrate of the present invention, the type or thickness of the resin constituting the adhesive layer of the present invention, and by applying an anti-reflective treatment and / or an anti-glare treatment to the surface of the substrate.

[0068] The thickness of the optical adhesive tape of the present invention is not particularly limited, but considering factors such as dimensional stability, strength, workability such as handling, and thinness, for example, the range is preferably 10 to 500 μm, more preferably 20 to 300 μm, and optimally 30 to 200 μm.

[0069] <Information>

[0070] Examples of materials constituting the substrate of the present invention include glass or plastic film. The above plastic film may include, for example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP) (e.g., trade name "Aton" (manufactured by JSR Corporation), trade name "Zeonora" (manufactured by Nippon Zeon Corporation), etc.), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), triacetylcellulose (TAC), polysulfone, polyarylate, polyetheretherketone (PEEK), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, etc., and may include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP), and polycarbonate (PC) which have excellent dimensional stability and are resistant to shrinkage. Polyetheretherketone (PEEK) and transparent polyimide (CPI) are preferred. Additionally, these plastic materials may be used individually or in combination of two or more types. The substrate of the present invention is a portion that is attached to a substrate (such as an image display panel) together with the adhesive layer when the optical adhesive tape of the present invention is attached to the substrate. A release liner that peels off during use (attachment) of the optical adhesive tape of the present invention is not included in the "substrate."

[0071] The substrate of the present invention has a film-like (substrate-like) form having a first surface and a second surface. The width direction (TD) and machine direction (MD) of the substrate of the present invention are determined during the manufacturing process of the substrate, for example, the direction in which the film-like extruded body flows after the extrusion molding of the raw resin material points to the machine direction (MD), and the width direction (TD) is a direction perpendicular to the machine direction.

[0072] The material of the present invention is not particularly limited as long as it is an optical member constituting the optical product, and may include various optical films such as cover members, polarizers, and phase difference plates, and is preferably used as a cover member. When the material of the present invention is a cover member, the second surface is, for example, the outermost surface of the optical product.

[0073] The glass transition point (Tg) of the substrate of the present invention is not particularly limited, but is preferably 60°C or higher. A configuration in which the glass transition point of the substrate of the present invention is 60°C or higher is desirable in that the mechanical properties of the image display device of the present invention are stable under the usage environment in the tiling display of the present invention. From the perspective of the stability of the mechanical properties of the image display device of the present invention, the glass transition point of the substrate may be 63°C or higher, or 65°C or higher. Furthermore, although the upper limit of the glass transition point of the substrate is not particularly limited, the glass transition point of the substrate is preferably 350°C or lower in order to simplify the molding process of the substrate, and may be 250°C or lower, 200°C or lower, 140°C or lower, 130°C or lower, or 125°C or lower.

[0074] The glass transition point (Tg) of the substrate of the present invention can be measured in accordance with JIS K 7121. The glass transition point (Tg) of the substrate of the present invention can be adjusted by the type of resin constituting the substrate of the present invention, etc.

[0075] The humidity expansion coefficient of the present invention is not particularly limited, but is 5×10 -5 It is preferable that it be / %RH or less. The humidity expansion coefficient of the present invention is 5×10 -5A configuration of / %RH or less is suitable in that the dimensional stability of the substrate of the present invention is improved in response to changes in humidity, and in the tiling display of the present invention, shrinkage or expansion of the image display device under the usage environment is suppressed, gaps between image display devices are not noticeable, and a good appearance is maintained, and shrinkage or expansion is minimal and transparency can be maintained without change. In terms of the dimensional stability of the substrate of the present invention, and the ability to maintain transparency without change and shrinkage or expansion, the humidity expansion coefficient of the substrate of the present invention is 3×10 -5 / %RH or less is desirable, and 2×10 -5 / %RH or less is acceptable.

[0076] The lower limit of the humidity expansion coefficient described in the present invention is not particularly limited, and while it is preferable for it to be lower, 0.001×10⁻⁶ -5 / %RH or higher is acceptable.

[0077] The humidity expansion coefficient of the substrate of the present invention can be specifically measured by the method described in the examples listed below. The humidity expansion coefficient of the substrate of the present invention can be adjusted by the type of resin constituting the substrate of the present invention or by conditions during the manufacture of the substrate (temperature, extrusion speed, etc.).

[0078] The substrate haze of the present invention is not particularly limited, but is preferably 5% or more. A configuration in which the substrate haze of the present invention is 5% or more is desirable in that it can prevent reflection caused by metal wiring or ITO wiring disposed on the substrate of an image display panel in the image display device of the present invention, and in that the gap between image display devices becomes difficult to see in the tiling display of the present invention, and is more preferably 6% or more, and may be 7% or more. The upper limit of the substrate haze of the present invention is not particularly limited, but from the perspective of visibility of the tiling display of the present invention, it is preferably 50% or less, and may be 40% or less, or 30% or less.

[0079] 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 or thickness of the resin constituting the substrate of the present invention, or by applying an anti-reflective treatment and / or an anti-glare treatment to the surface of the substrate.

[0080] The reflectance of the substrate of the present invention is not particularly limited, but is preferably 5% or less. A configuration in which the reflectance of the substrate of the present invention is 5% or less is desirable in that it prevents reflection caused by metal wiring or ITO wiring disposed on the substrate of an image display panel in the image display device of the present invention, and in that the gap between image display devices becomes difficult to see in the tiling display of the present invention, and is more preferably 3% or less, and may be 1.5% or less. The lower limit of the reflectance of the substrate of the present invention is not particularly limited, but may be 0.1% or more, or 0.3% or more.

[0081] 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 or thickness of the resin constituting the substrate of the present invention, or by applying an anti-reflection treatment and / or an anti-glare treatment to the surface of the substrate.

[0082] The thickness of the substrate of the present invention is not particularly limited, but considering factors such as dimensional stability, strength, workability including handling, and thinness, for example, 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, is in the range of 1.30 to 1.80, and preferably in the range of 1.40 to 1.70.

[0083] It is preferable that the second surface of the substrate of the present invention be treated with a reflective surface and / or an anti-glare treatment. The configuration in which the second surface of the substrate of the present invention is treated with a reflective surface and / or an anti-glare treatment is preferred in that it can prevent reflection caused by metal wiring or ITO wiring disposed on the substrate of the image display device of the present invention. In addition, it is also preferred in that the gap between image display devices becomes difficult to see in the tiling display of the present invention.

[0084] As for the above anti-reflection treatment, known anti-reflection treatments may be used without particular limitation, and for example, anti-reflection (AR) treatment may be used.

[0085] As for the above anti-reflection (AR) treatment, known AR treatments may be applied without particular limitation. Specifically, it may be performed by forming an optical thin film with strictly controlled thickness and refractive index, or by stacking two or more layers of said optical thin films to form an anti-reflection layer (AR layer) on the second surface of the substrate of the present invention. The AR layer exhibits an anti-reflection function by utilizing the optical interference effect to cancel out the reversed phases of incident light and reflected light. The wavelength range of visible light that exhibits the anti-reflection function is, for example, 380 to 780 nm, and the wavelength range with particularly high visual sensitivity is in the range of 450 to 650 nm. It is preferable to design the AR layer to minimize the reflectance at the center wavelength of 550 nm.

[0086] As the above AR layer, generally, a multilayer anti-reflection layer having a structure of stacking 2 to 5 layers of optical thin films (thin films with strictly controlled thickness and refractive index) can be used. 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-reflection effect can be further improved, and it is possible to make the spectral reflection characteristics uniform (flat) in the visible light region. Since high thickness precision is required for the above optical thin films, generally, each layer is formed by dry methods such as vacuum deposition, sputtering, and CVD.

[0087] In addition, the above AR layer may also be formed by a coating solution for forming an anti-reflective layer. The above coating solution for forming an anti-reflective layer may include, for example, a resin, a fluorine element-containing additive, hollow particles, solid particles, and a diluent solvent, and may be prepared by, for example, mixing these.

[0088] Examples of the above resins include thermosetting resins and ionizing radiation-curing resins that cure under ultraviolet rays or light. As the above resin, it is also possible to use commercially available thermosetting resins or UV-curing resins.

[0089] As the above-mentioned thermosetting resin or UV-curing resin, for example, a curable compound having at least one of an acrylate group and a methacrylate group that is cured by heat, light (ultraviolet rays, etc.) or electron beams, etc. may be used, and examples include silicone resin, polyester resin, polyether resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol-polyene resin, polyfunctional compounds such as polyhydric alcohols, oligomers or prepolymers such as acrylates or methacrylates. One type may be used alone, or two or more types may be used in combination.

[0090] For the resin above, a reactive diluent having at least one of an acrylate group and a methacrylate group may be used. For example, the reactive diluent described in Japanese Patent Publication No. 2008-88309 may be used, and includes, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, etc. As the reactive diluent, acrylates with three or more functional groups and methacrylates with three or more functional groups are preferred. This is because the hardness of the second surface of the substrate of the present invention can be made excellent. Examples of the reactive diluent include butanediol glycerin ether diacrylate, acrylate of isocyanuric acid, methacrylate of isocyanuric acid, etc. One type may be used alone, or two or more types may be used in combination. The above resin may have a weight-average molecular weight before curing of, for example, 100 or more, 300 or more, 500 or more, 1,000 or more, or 2,000 or more, or 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 decreases, but there is a tendency for cracking to occur when bent. On the other hand, if the weight-average molecular weight before curing is low, the crosslinking density between molecules improves, and the hardness tends to increase.

[0091] As the above resin, it is preferable to include a polyfunctional acrylate (e.g., pentatritol triacrylate).

[0092] For curing the above-mentioned curable resin, a curing agent may be added, for example. The curing agent is not particularly limited, and known polymerization initiators (e.g., thermal polymerization initiators, photopolymerization initiators, etc.) may be appropriately used. The amount of the curing agent added is not particularly limited, but with respect to 100 parts by weight of the resin in the coating solution for forming the anti-reflective layer, for example, it may be 0.5 parts by weight or more, 1.0 parts 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, or 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.

[0093] The above-mentioned fluorine element-containing additive is not particularly limited, but may be, for example, an organic compound or an inorganic compound containing fluorine in its molecule. The above-mentioned organic compound is not particularly limited, but examples include a fluorine-containing antifouling coating agent, a fluorine-containing acrylic compound, a fluorine and silicon-containing acrylic compound, etc. Specifically, examples of the above-mentioned organic compound include the trade name "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd. and the trade name "Megapac" manufactured by DIC Co., Ltd. The above-mentioned inorganic compound is also not particularly limited. The amount of the above-mentioned fluorine element-containing additive is not particularly limited, but, for example, with respect to the total weight of the solid in the coating solution for forming the anti-reflective layer, the weight of the fluorine element in the solid may be, for example, 0.05 weight% or more, 0.1 weight% or more, 0.15 weight% or more, 0.20 weight% or more, or 0.25 weight% or more, or 20 weight% or less, 15 weight% or less, 10 weight% or less, 5 weight% or less, or 3 weight% or less. In addition, for example, with respect to 100 parts by weight of the resin in the coating solution for forming the anti-reflective layer, the weight of the fluorine element-containing additive 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.

[0094] The above hollow particles are not particularly limited, but may be, for example, silica particles, acrylic particles, acrylic-styrene copolymer particles, etc. Examples of the above silica particles include the trade names "Srulia 5320" and "Srulia 4320" manufactured by Nikki Shokubai Kasei Kogyo Co., Ltd. The weight-average particle size of the above 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 above hollow particles is not particularly limited, and may be, for example, approximately spherical in the form of beads or irregular in shape such as powder, but it is preferred to be approximately spherical, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. By adding the above hollow particles, for example, a low refractive index of the anti-reflection layer and good anti-reflection properties can be realized. The amount of the hollow particles added is not particularly limited, but with respect to 100 parts by weight of the resin in the coating solution for forming the anti-reflection layer, for example, it may be 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 perspective of achieving a low refractive index of the anti-reflection layer, it is desirable that the amount of the hollow particles added is not too small, and from the perspective of securing the mechanical properties of the anti-reflection layer, it is desirable that the amount of the hollow particles added is not too large.

[0095] The above-mentioned solid particles are not particularly limited, but may be, for example, silica particles, zirconium oxide particles, titanium-containing particles (for example, titanium oxide particles), etc. Examples of the above-mentioned silica particles include, for example, the product names “MEK-2140Z-AC”, “MIBK-ST”, “IPA-ST” manufactured by Nissan Chemical Co., Ltd. The weight-average particle size of the above-mentioned 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 above solid particles is not particularly limited and, for example, may be approximately spherical in the form of beads or irregular in shape such as powder, but it is preferable that they be approximately spherical, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. By adding the above solid particles, for example, the fluorine element-containing additive is easily distributed on the surface of the coating solution for forming the anti-reflective layer, and the anti-reflective layer has excellent scratch resistance, low refractive index, and good anti-reflective properties can be realized. The amount of the above solid particles added is not particularly limited, but with respect to 100 parts by weight of the resin in the coating solution for forming the anti-reflective layer, for example, it may be 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, or 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.

[0096] The above dilution solvent may be a mixed solvent including, for example, MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate). In this case, the mixing ratio is not particularly limited, but when the weight of MIBK is 100% by weight, the weight of PMA may be, for example, 20% by weight or more, 50% by weight or more, 100% by weight or more, 150% by weight or more, or 200% by weight or more, or 400% by weight or less, 350% by weight or less, 300% by weight or less, or 250% by weight or less.

[0097] The above dilution solvent may be a mixed solvent containing, for example, TBA (tert-tert-butyl alcohol) in addition to MIBK and PMA. In this case, the mixing ratio is not particularly limited, but when the weight of MIBK is 100% by weight, the weight of PMA may be, for example, 10% by weight or more, 30% by weight or more, 50% by weight or more, 80% by weight or more, or 100% by weight or more, or 200% by weight or less, 180% by weight or less, 150% by weight or less, 130% by weight or less, or 110% by weight or less. In addition, when the weight of MIBK is 100% by weight, the weight of TBA may be, for example, 10% by weight or more, 30% by weight or more, 50% by weight or more, 80% by weight or more, or 100% by weight or more, or 200% by weight or less, 180% by weight or less, 150% by weight or less, 130% by weight or less, or 110% by weight or less.

[0098] The amount of the diluting solvent added is not particularly limited, but for example, the weight of the solid content relative to the total weight of the coating solution for forming an anti-reflective layer 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 perspective of ensuring coating properties (wetting, leveling), it is desirable that the content of the solid content is not too high, and from the perspective of preventing appearance defects caused by drying, such as uneven air drying and whitening, it is desirable that the content of the solid content is not too low.

[0099] Next, the coating solution for forming the anti-reflection layer is applied to the second surface of the substrate of the present invention (the coating process). The coating method is not particularly limited, and known coating methods such as, for example, fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating may be appropriately used. The amount of the coating solution for forming the anti-reflection layer is also not particularly limited, but the thickness of the anti-reflection layer formed 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.

[0100] Next, the coating solution for forming the anti-reflective layer applied is dried to form a coating film (the coating film forming process). The drying temperature is not particularly limited, but may be in the range of, for example, 30 to 200°C. The drying temperature may be, for example, 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, or 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 specifically limited, but, for example, it may be 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, or 150 seconds or less, 130 seconds or less, 110 seconds or less, or 90 seconds or less.

[0101] In addition, the above film may be cured (curing process). The curing may be performed, for example, by heating, light irradiation, etc. 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. In the above ultraviolet curing, the irradiation amount of the energy source is preferably 50 to 500 mJ / cm² as the integrated exposure amount at an ultraviolet wavelength of 365 nm. If the irradiation amount is 50 mJ / cm² or more, curing proceeds easily and the hardness of the formed anti-reflective layer is likely to increase. In addition, if it is 500 mJ / cm² or less, discoloration of the formed anti-reflective layer can be prevented.

[0102] As for the above anti-glare (AG) treatment, known AG treatments can be applied without particular limitation, and, for example, can be carried out by forming an anti-glare layer on the second surface of the substrate of the present invention. As for the above anti-glare layer, known ones can be adopted without limitation, and generally, it is formed as a layer in which inorganic or organic particles as anti-glare agents are dispersed in a resin.

[0103] The above anti-glare layer is not particularly limited, but is formed using an anti-glare layer forming material including, for example, a resin, particles, and a thixotropy-importing agent, and a convex shape is formed on the surface of the anti-glare layer by aggregating the particles and the thixotropy-importing agent. With this configuration, the anti-glare layer has excellent display characteristics that combine anti-glare properties and prevention of white blurring, and even though the anti-glare layer is formed by aggregating particles, it can prevent the occurrence of protrusions on the surface of the anti-glare layer that become appearance defects, thereby improving the product yield.

[0104] Examples of the above resins include thermosetting resins and ionizing radiation-curing resins that cure with ultraviolet rays or light. As the above resin, it is also possible to use commercially available thermosetting resins or UV-curing resins.

[0105] As the above-mentioned thermosetting resin or UV-curing resin, for example, a curable compound having at least one of an acrylate group and a methacrylate group that is cured by heat, light (ultraviolet rays, etc.) or electron beams, etc. may be used, and examples include silicone resin, polyester resin, polyether resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol-polyene resin, polyfunctional compounds such as polyhydric alcohols, oligomers or prepolymers such as acrylates or methacrylates. One type may be used alone, or two or more types may be used in combination.

[0106] For the resin above, a reactive diluent having at least one of an acrylate group and a methacrylate group may be used. For example, the reactive diluent described in Japanese Patent Publication No. 2008-88309 may be used, and includes, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, etc. As the reactive diluent, acrylates with three or more functional groups and methacrylates with three or more functional groups are preferred. This is because the hardness of the anti-glare layer can be made excellent. Examples of reactive diluents include butanediol glycerin ether diacrylate, acrylate of isocyanuric acid, methacrylate of isocyanuric acid, etc. One type may be used alone, or two or more types may be used in combination.

[0107] As for the resin, it is preferable to include a urethane acrylate resin, and it is more preferable to be a copolymer of a curable urethane acrylate resin and a polyfunctional acrylate (e.g., pentatritol triacrylate).

[0108] The particles for forming the above anti-glare layer primarily function to impart anti-glare properties by making the surface of the formed anti-glare layer uneven, and also to control the haze value of the anti-glare layer. The haze value of the anti-glare layer can be designed by controlling the difference in refractive index between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited and may 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. In addition, the above organic particles are not particularly limited and may 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. Among these inorganic particles and organic particles, one type may be used alone, or two or more types may be used in combination.

[0109] The weight-average particle size (D) of the above particles is preferably within the range of 2.5 to 10 μm. By setting the weight-average particle size of the above particles to the above range, for example, the anti-glare properties are superior, and white clouding can also be prevented. More preferably, the weight-average particle size of the above particles is within the range of 3 to 7 μm. In addition, the weight-average particle size of the above particles can be measured, for example, by the Coulter count method. For example, by using a particle size distribution measuring device using the pore electrical resistance method (product name: Coulter Multisizer, manufactured by Beckmann Coulter), the number and volume of the particles are measured and the weight-average particle size is calculated by measuring the electrical resistance of the electrolyte corresponding to the particle volume when the particles pass through the pores.

[0110] The shape of the above particles is not particularly limited and, for example, may be approximately spherical in the form of beads or may be irregular such as powder, but it is preferred to be approximately spherical, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0111] The ratio of the particles in the above anti-glare layer is preferably in the range of 0.2 to 12 parts by weight per 100 parts by weight of the resin, 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. By using the above range, for example, the anti-glare properties are superior, and white clouding can also be prevented.

[0112] The above anti-glare layer may include a thixotropy-importing agent. By including the above thixotropy-importing agent, the aggregation state of the particles can be easily controlled. Examples of thixotropy-importing agents for forming the above anti-glare layer include organic clay, oxidized polyolefin, modified urea, etc.

[0113] The above organic clay is preferably an organically treated clay to improve affinity with the resin. As an example of the organic clay, a layered organic clay may be used. The above organic clay may be self-prepared or commercially available products may be used. Examples of commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasif ME-100, Somasif MAE, Somasif MTE, Somasif MEE, and Somasif MPE (product names, all manufactured by Coff Chemical Co., Ltd.); Examples include 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 Kogyo Co., Ltd.); Thixogel VZ, Kraton HT, Kraton 40 (product names, all manufactured by Rockwood Additives Co., Ltd.).

[0114] The above-mentioned polyolefin oxide may be prepared at home or commercially available products may be used. Examples of the above-mentioned commercially available products include Dispalon 4200-20 (product name, manufactured by Kusumoto Kasei Co., Ltd.) and Folonon SA300 (product name, manufactured by Kyoesha Chemical Co., Ltd.).

[0115] The above modified urea is a reaction product of an isocyanate monomer or its adduct and an organic amine. The above modified urea may be self-prepared or a commercially available product may be used. Examples of commercially available products include BYK410 (manufactured by Bic Chem).

[0116] The above thixotropic agent may be used alone or in combination with two or more types.

[0117] It is preferable that the height of the average roughness line of the anti-glare layer on the convex upper portion 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 suitably possible to prevent the formation of protrusions that become appearance defects on the convex upper portion. By having a convex portion of such height, the anti-glare layer can make it difficult to cause appearance defects. Here, the height of the average line can be measured, for example, by the method described in Japanese Patent Publication No. 2017-138620.

[0118] The ratio of the thixotropy-imparting agent in the above anti-glare layer is preferably in the range of 0.1 to 5 parts by weight per 100 parts by weight of the resin, and more preferably in the range of 0.2 to 4 parts by weight.

[0119] The thickness (d) of the anti-glare layer is not particularly limited, but is preferably within the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer to the above range, for example, the occurrence of curling in the optical adhesive tape of the present invention can be prevented, and problems of reduced productivity such as poor returnability can be avoided. In addition, when the thickness (d) is within the above range, the weight average particle size (D) of the particles is preferably within the range of 2.5 to 10 μm, as described above. By having the above combination of the thickness (d) of the anti-glare layer and the weight average particle size (D) of the particles, the anti-glare properties can be made superior. More preferably, the thickness (d) of the anti-glare layer is within the range of 3 to 8 μm.

[0120] It is preferable that the relationship between the thickness (d) of the anti-glare layer and the weight-average particle size (D) of the particles be within the range of 0.3 ≤ D / d ≤ 0.9. By having this relationship, the anti-glare layer can be made to have superior anti-glare properties, prevent whitening, and be free from appearance defects.

[0121] In the optical adhesive tape of the present invention, as described above, the anti-glare layer forms a convex shape on the surface of the anti-glare layer by aggregating the particles and the thixotropy-importing agent. In the aggregated portion forming the convex shape, the particles exist in a state where they are gathered in multiple numbers in the direction of the plane of the anti-glare layer. As a result, the convex shape is formed in a smooth shape. By having a convex shape of this shape, the anti-glare layer can maintain anti-glare properties while also preventing white blurring and making it difficult to cause appearance defects.

[0122] The surface shape of the anti-glare layer can be arbitrarily designed by controlling the aggregation state of the particles included 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., chemical modification state of the particle surface, affinity for solvent or resin, etc.), the type and combination of the resin (binder) or solvent. Here, the aggregation state of the particles can be controlled by a thixotropy-imparting agent included 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 upper portion can be made into a smooth shape.

[0123] In the optical adhesive tape of the present invention, when the substrate of the present invention is formed of a resin or the like, it is preferable to have a penetration layer at the interface between the substrate of the present invention and the anti-glare layer. The penetration layer is formed by a resin component included in the material forming the anti-glare layer penetrating into the substrate of the present invention. It is desirable that the penetration layer is formed so as to 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-based resin and the resin included in the anti-glare layer is an acrylic resin, the penetration layer can be formed. The penetration layer can be confirmed and its thickness measured, for example, by observing a cross-section of the optical adhesive tape of the present invention using a transmission electron microscope (TEM).

[0124] Even when applied to the optical adhesive tape of the present invention having such a penetration layer, a desired smooth surface irregularity shape that achieves both anti-glare properties and prevention of white blurring can be easily formed. It is preferable to form the penetration layer thicker to improve adhesion, especially for substrates that have insufficient adhesion to the anti-glare layer.

[0125] In the above anti-glare layer, it is preferable that there is no more than one appearance defect with a maximum diameter of 200 μm or more per 1 m² of the anti-glare layer. More preferably, there are no appearance defects.

[0126] In the uneven shape of the surface of the anti-glare layer, it is preferable that the average inclination angle θa(°) is in the range of 0.1 to 5.0, more preferable that it is in the range of 0.3 to 4.5, even more preferable that it is in the range of 1.0 to 4.0, and particularly preferable that it is 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, for example, by the method described in Japanese Patent Publication No. 2017-138620.

[0127] Average slope angle θa=tan⁻¹Δa (1)

[0128] In the above formula (1), Δa is the value obtained by dividing the sum of the difference (height h) between the peak of an adjacent mountain and the lowest point of a valley (h1+h2+h3…+hn) by the standard length L of the roughness curve specified in JIS B 0601 (1994 edition), as shown in the following formula (2). The above roughness curve is a curve obtained by removing surface curvature components longer than a predetermined wavelength from a cross-sectional curve using a phase difference compensation high-pass filter. Furthermore, the above cross-sectional curve is the outline that appears in the cut section when the target surface is cut by a plane perpendicular to the target surface.

[0129] Δa=(h1+h2+h3…+hn) / L (2)

[0130] If θa is within the above range, the anti-glare properties are superior, and white blurring can also be prevented.

[0131] In forming the above anti-glare layer, it is preferable that the prepared anti-glare layer forming material (coating liquid) exhibits thixotropic properties, and it is preferable that the Ti value specified below is in the range of 1.3 to 3.5, and more preferably in the range of 1.3 to 2.8.

[0132] Ti value = β1 / β2

[0133] Here, β1 is the viscosity measured under conditions of a shear rate of 20 (1 / s) using HAAKE Rheostress 6000, and β2 is the viscosity measured under conditions of a shear rate of 200 (1 / s) using HAAKE Rheostress 6000.

[0134] If the Ti value is less than 1.3, appearance defects are prone to occur, and properties regarding anti-glare and white fading deteriorate. In addition, if the Ti value exceeds 3.5, the particles are prone to becoming dispersed, making it difficult for them to aggregate.

[0135] The method for manufacturing the above anti-glare layer is not particularly limited and may be manufactured by any method, but, for example, it can be manufactured by preparing an anti-glare layer forming material (coating solution) comprising the above resin, the above particles, the above thixotropy-imparting agent, and a solvent, applying the above anti-glare layer forming material (coating solution) to 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. A method of imparting an uneven shape using a mold transfer method, sandblasting, an embossing roll, or other suitable methods may also be used.

[0136] The above solvent is not particularly limited and various solvents may be used; one type may be used alone, or two or more types may be used in combination. Depending on the composition of the resin, the type and content of the particles and the thixotropy-imparting agent, there exists an optimal type of solvent or solvent ratio. As a solvent, although not particularly limited, examples 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; and aliphatic hydrocarbons such as hexane, heptane, and octane. Examples include aromatic hydrocarbons such as benzene, toluene, and xylene.

[0137] As a material for the present invention, for example, when a penetration layer is formed by employing a polyester resin, a solvent for the polyester resin may be suitably used. Examples of such solvents include ethyl acetate, methyl ethyl ketone, cyclopentanone, etc.

[0138] By appropriately selecting the above solvent, thixotropic properties can be well expressed for the anti-glare layer forming material (coating solution) by the thixotropic agent. For example, when using organic clay, toluene and xylene may be suitably used alone or in combination; for example, when using polyolefin oxide, methyl ethyl ketone, ethyl acetate, and propylene glycol monomethyl ether may be suitably used alone or in combination; for example, when using modified urea, butyl acetate and methyl isobutyl ketone may be suitably used alone or in combination.

[0139] Various leveling agents may be added to the above anti-glare layer forming material. As the leveling agent, for the purpose of preventing coating non-uniformity (uniformity of the coating surface), for example, a fluorine-based or silicone-based leveling agent may be used. The leveling agent can be appropriately selected depending on whether antifouling properties are required on the surface of the above anti-glare layer, or whether a layer containing an anti-reflection layer (low refractive index layer) or an interlayer filler is formed on the anti-glare layer. For example, by including the above thixotropic agent, thixotropic properties can be expressed in the coating solution, making it difficult for coating non-uniformity to occur. For this reason, it has the advantage of being able to expand the options for the leveling agent.

[0140] 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, with respect to 100 parts by weight of the resin.

[0141] In the above anti-glare layer forming material, pigments, fillers, dispersants, plasticizers, UV absorbers, surfactants, antifouling agents, antioxidants, etc. may be added as needed, within a range that does not impair performance. One type of these additive may be used alone, or two or more types may be used in combination.

[0142] In the above anti-glare layer forming material, a conventionally known photopolymerization initiator, such as that described in Japanese Patent Publication No. 2008-88309, may be used.

[0143] As a method for coating the above anti-glare layer forming material on the second surface of the substrate of the present invention, coating methods such as fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating may be used.

[0144] The above anti-glare layer forming material is applied to form a coating film on the substrate of the present invention, and the coating film is cured. Prior to the curing, it is preferable to dry the coating film. The drying may be, for example, natural drying, air drying by blowing wind, heat drying, or a combination of these methods.

[0145] 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 preferably 50 to 500 mJ / cm² as the integrated exposure dose at an ultraviolet wavelength of 365 nm. If the irradiation dose is 50 mJ / cm² or higher, curing becomes more sufficient, and the hardness of the anti-glare layer formed becomes more sufficient. In addition, if it is 500 mJ / cm² or lower, discoloration of the anti-glare layer formed can be prevented.

[0146] In accordance with the above, the anti-glare layer can be formed on the second surface of the substrate of the present invention. Additionally, the anti-glare layer may be formed by a manufacturing method other than the method described above. The hardness of the anti-glare layer is influenced by the thickness of the layer in terms of pencil hardness, but it is preferable that it have a hardness of 2H or higher.

[0147] The above anti-glare layer may have a multi-layer structure in which two or more layers are stacked.

[0148] The aforementioned AR layer (low refractive index layer) may be placed on the above anti-glare layer. For example, when an optical adhesive tape is mounted on an image display device, one of the factors that reduces image visibility is the reflection of light at the interface between air and the anti-glare layer. The AR layer reduces such surface reflection. In addition, the above anti-glare layer and the anti-reflection layer may each have a multi-layer structure in which two or more layers are stacked.

[0149] In addition, to prevent the adhesion of contaminants and to improve the ease of removing attached contaminants, it is preferable to laminate a contamination prevention layer formed of a fluorine-containing silane compound or a fluorine-containing organic compound, etc., onto the anti-reflection layer and / or anti-glare layer.

[0150] It is preferable to perform surface treatment on at least one of the substrate of the present invention and the anti-glare layer. When the surface of the substrate of the present invention is surface treated, the adhesion with the anti-glare layer is further improved. In addition, when the surface of the anti-glare layer is surface treated, the adhesion with the AR layer is further improved.

[0151] In order to prevent curling of the substrate of the present invention, a solvent treatment may be performed on the other side of the anti-glare layer. In addition, to prevent curling, a transparent resin layer may be formed on the other side of the anti-glare layer.

[0152] <Adhesive layer>

[0153] The adhesive layer of the present invention may be an adhesive layer that does not have a substrate (substrate layer), or an adhesive layer of the type that has a substrate. Furthermore, in this specification, an adhesive layer that does not have a substrate (substrate layer) may be referred to as a "substrate-free adhesive layer," and an adhesive layer of the type that has a substrate may be referred to as a "substrate-equipped adhesive layer." Examples of the above-mentioned substrate-free adhesive layer include a single-layer adhesive layer comprising only the adhesive layer of the present invention, or an adhesive layer comprising the adhesive layer of the present invention and other adhesive layers (adhesive layers other than the adhesive layer of the present invention). Additionally, examples of the above-mentioned adhesive layer equipped with a substrate include an adhesive layer having the adhesive layer of the present invention on both sides of a substrate, or an adhesive layer having the adhesive layer of the present invention on one side of a substrate and other adhesive layers on the other side. As the “substrate (substrate layer)” constituting the “adhesive layer having a substrate,” a plastic film similar to the substrate of the present invention may be used.

[0154] The shear force of the adhesive layer of the present invention (the shear force when an adhesive area of ​​1 cm² is bonded to a resin plate and tensile at a tensile speed of 0.06 mm / min in the shear direction at 23°C) is 20 N / cm² or less. The configuration in which the shear force of the adhesive layer of the present invention is 20 N / cm² or less is desirable in that the adhesive layer of the present invention can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or delamination. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or delamination of the optical adhesive tape of the present invention and to follow the step, the shear force of the adhesive layer of the present invention is preferably 15 N / cm² or less, and may be 13 N / cm² or less. Although the lower limit of the shear force of the adhesive layer of the present invention is not particularly limited, from the perspective of processability, such as the problem of the adhesive layer leaking out from the end when storing the optical adhesive tape of the present invention, it is preferable that it be 5 N / cm² or more, and 7 N / cm² or more.

[0155] The shear force of the adhesive layer of the present invention is measured by the shear force measurement in the examples disclosed later. The shear force 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 (e.g., the type, molecular weight, and amount of base polymer, monomer composition, type and amount of functional groups, and type and amount of crosslinking agent) or curing conditions (heating conditions, radiation irradiation conditions), etc.

[0156] It is preferable that the glass transition point (Tg) of the adhesive layer of the present invention be -10°C or lower. The configuration in which the Tg of the adhesive layer of the present invention is -10°C or lower is desirable in that the stress relaxation properties of the adhesive layer are maintained even under low-temperature environments, allowing the adhesive layer to sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or delamination and ensuring sufficient adhesion to the substrate. In terms of suppressing lifting or delamination in the image display device of the present invention and ensuring good adhesion to the substrate, the glass transition point of the adhesive layer of the present invention is preferably -15°C or lower, and may be -20°C or lower. Although the lower limit of the Tg of the adhesive layer of the present invention is not particularly limited, from the perspective of processability, such as preventing the problem of the adhesive layer leaking out from the end during storage of the optical adhesive tape of the present invention, it is preferably -50°C or higher, and may be -40°C or higher.

[0157] The glass transition point (Tg) of the adhesive layer of the present invention is measured by dynamic viscoelasticity measurement in the embodiments disclosed later. The glass transition point (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 (e.g., type, molecular weight, amount, monomer composition, type and amount of functional groups, type and amount of crosslinking agent) or curing conditions (heating conditions, radiation irradiation conditions), etc.

[0158] The storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, but it is preferably 80 kPa or less. The configuration in which the storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is 80 kPa or less is desirable in that the adhesive layer of the present invention can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention and suppress lifting or delamination. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or delamination of the optical adhesive tape of the present invention and to follow the step, the storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is more preferably 70 kPa or less, and may be 60 kPa or less or 50 kPa or less. Although the lower limit of the storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, from the perspective of processability such as the problem of the adhesive layer leaking out from the end when storing the optical adhesive tape of the present invention, it is preferable that it be 1 kPa or more, and it may be 5 kPa or more.

[0159] The loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, but is preferably 0.15 or higher. The configuration in which the loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is 0.15 or higher is desirable in that the adhesive layer of the present invention can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or delamination. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or delamination of the optical adhesive tape of the present invention and to follow the step, the loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is preferably 0.2 or higher, and may be 0.25 or higher, or 0.3 or higher. The upper limit of the loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, but from the perspective of processability, such as preventing the adhesive layer from leaking out from the end when storing the optical adhesive tape of the present invention, it is preferable to have a value of 1 or less, and it may be 0.8 or less.

[0160] The storage modulus and loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz are measured by dynamic viscoelasticity measurements in the examples to be posted later. The storage modulus and loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz can be adjusted by the composition of the adhesive composition for forming the adhesive layer of the present invention (e.g., type or molecular weight, amount of base polymer, monomer composition, type and amount of functional group, type and amount of crosslinking agent) or curing conditions (heating conditions, radiation irradiation conditions), etc.

[0161] The 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, but it is preferably 10 N / cm² or less. A configuration in which the 300% tensile residual stress value of the adhesive layer of the present invention is 10 N / cm² or less is desirable in that the adhesive layer of the present invention can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or delamination. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or delamination of the optical adhesive tape of the present invention and to follow the step, the 300% tensile residual stress value of the adhesive layer of the present invention is more preferably 7 N / cm² or less, and may be 5 N / cm² or less. Although the lower limit of the 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, from the perspective of processability such as preventing the adhesive layer from leaking out from the end when storing the optical adhesive tape of the present invention, it is preferable to have a value of 1 N / cm² or more, and it may also be 1.5 N / cm² or more.

[0162] The 300% tensile residual stress value of the adhesive layer of the present invention is measured by measuring the 300% tensile residual stress value in the examples listed 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 (e.g., the type or molecular weight, amount used, monomer composition, type and amount of functional groups, type and amount of crosslinking agent) or curing conditions (heating conditions, radiation irradiation conditions), etc.

[0163] The recovery rate obtained in the following shear test of the adhesive layer of the present invention is not particularly limited, but is preferably 95% or less.

[0164] <Shear Test>

[0165] The amount of deformation A (%) is measured when a shear force of 500 Pa in the twisting direction at 60°C is applied from the top and bottom of a disc-shaped adhesive layer with a thickness of 2 mm and a diameter of 7.9 mm for 600 seconds, and the amount of deformation B (%) is measured when the shear force is maintained at 0 Pa for 1800 seconds, and the recovery rate (%) is calculated from the following formula.

[0166] Restoration rate (%) = (Deformation A - Deformation B) / Deformation A × 100

[0167] In this specification, when "deformation amount A," "deformation amount B," and "restoration rate" are used, unless otherwise specifically stated, they refer to the "deformation amount A," "deformation amount B," and "restoration rate" obtained from the shear test described above.

[0168] The above "shear test" will be explained with reference to the drawings. FIG. 5 is a schematic diagram for explaining the shear test, where 40 represents an adhesive layer, and 41 and 42 represent parallel plates.

[0169] The adhesive layer (40) is a disc-shaped adhesive layer with a thickness of 2 mm and a diameter of 7.9 mm and is composed of the adhesive layer of the present invention, and the parallel plates (41 and 42) each have an upper surface and a lower surface with a diameter of 7.9 mm and are composed of, for example, stainless steel (Fig. 5(a)). The upper surface of the parallel plate (41) and the lower surface of the parallel plate (42) are positioned to come into contact with the lower surface and upper surface of the adhesive layer (40), respectively (Fig. 5(b)). Next, the ambient temperature is set to 60°C, and a torsional shear force F of 500 Pa is applied to the adhesive layer (40) for 600 seconds (Fig. 5(c)). Subsequently, the shear force of the parallel plates (41 and 42) is released, and the plate is left at a shear force of 0 Pa for 1800 seconds (Fig. 5(d)). “Deformation A” is the percentage (%) of change in the twisting direction at the point in time (Fig. 5 (c)) when a shear force F is applied for 600 seconds to the outer circumference (100%) of the adhesive layer (40) at the beginning (Fig. 5 (b)). “Deformation B” is the percentage (%) of change in the twisting direction at the point in time (Fig. 5 (d)) when the adhesive layer (40) at the beginning (Fig. 5 (b)) is left for 1800 seconds with a shear force of 0 Pa after a shear force F is applied for 600 seconds to the outer circumference (100%) of the adhesive layer (40) at the beginning (Fig. 5 (b)). The recovery rate (%) is calculated from the following formula.

[0170] Restoration rate (%) = (Deformation A - Deformation B) / Deformation A × 100

[0171] The configuration in which the recovery rate of the adhesive layer of the present invention is 95% or less is desirable in that the adhesive layer can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or peeling, and maintaining transparency without change. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or peeling of the optical adhesive tape of the present invention, maintain transparency without change, and follow the step, the recovery rate of the adhesive layer of the present invention is more preferably 94% or less, and may be 93.5% or less. Although the lower limit of the adhesive layer recovery rate of the present invention is not particularly limited, from the perspective of processability such as preventing the adhesive layer from leaking out from the end when storing the optical adhesive tape of the present invention, 70% or more is preferred, and 80% or more, or 85% or more may be used.

[0172] The deformation amount A of the adhesive layer of the present invention is not particularly limited, but is preferably 3% or more. A configuration in which the deformation amount A of the adhesive layer of the present invention is 3% or more is desirable in that the adhesive layer can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention and suppress lifting or peeling. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or peeling of the optical adhesive tape of the present invention and to follow the step, the deformation amount A of the adhesive layer of the present invention is more preferably 4% or more, and may be 5% or more. Although the upper limit of the deformation amount A of the present invention is not particularly limited, from the perspective of processability, such as the difficulty of the adhesive layer leaking out from the end when storing the optical adhesive tape of the present invention, and from the perspective of maintaining transparency without change, it is preferable that it be 25% or less, and it may be 20% or less, or 15% or less.

[0173] The deformation amount B of the adhesive layer of the present invention is not particularly limited, but is preferably 0.1% or more. A configuration in which the deformation amount B of the adhesive layer of the present invention is 0.1% or more is desirable in that the adhesive layer can sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention and suppress lifting or delamination. In addition, when there is a step with an uneven shape caused by wiring, etc. on a substrate such as an image display panel, it is also desirable in that the adhesive layer can sufficiently follow said step and fill without leaving bubbles, etc. In order to suppress lifting or delamination of the optical adhesive tape of the present invention and to follow the step, the deformation amount B of the adhesive layer of the present invention is preferably 0.2% or more, and may be 0.3% or more. Although the upper limit of the deformation amount B of the present invention is not particularly limited, from the perspective of processability, such as the difficulty of the adhesive layer leaking out from the end when storing the optical adhesive tape of the present invention, and from the perspective of maintaining transparency without change, it is preferable that it be 10% or less, and it may be 8% or less, or 5% or less.

[0174] The deformation amount A, deformation amount B, and recovery rate of the adhesive layer of the present invention are specifically measured by measuring the deformation amount A, deformation amount B, and recovery rate in the examples disclosed later. The deformation amount A, deformation amount B, and recovery rate 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 (e.g., the type, molecular weight, and amount of base polymer, monomer composition, type and amount of functional groups, and type and amount of crosslinking agent) or curing conditions (heating conditions, radiation irradiation conditions), etc.

[0175] The adhesive constituting the adhesive layer of the present invention is not particularly limited, but examples include acrylic adhesives, rubber adhesives, vinylalkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, epoxy adhesives, etc. Among these, acrylic adhesives are preferred as the adhesive constituting the adhesive layer in terms of transparency, adhesiveness, weather resistance, cost, and ease of designing the adhesive. That is, the adhesive layer of the present invention is preferably an acrylic adhesive layer composed of acrylic adhesives. The adhesive may be used alone or in combination of two or more types.

[0176] The above acrylic adhesive layer contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer comprising an acrylic monomer (a monomer having a (meth)acryloyl group in its molecule) as a monomer component constituting the polymer. Preferably, the acrylic polymer is a polymer comprising an alkyl (meth)acrylate ester as a monomer component constituting the polymer. Additionally, the acrylic polymer may be used alone or in combination of two or more types.

[0177] 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 beam curing type, a thermal melt type (hot melt type), etc. Among these, a solvent type or an active energy beam curing type adhesive composition is preferred in terms of productivity and ease of obtaining an adhesive layer with excellent optical properties or appearance. In particular, an active energy beam curing type adhesive composition is preferred in terms of ease of controlling the various properties of the adhesive layer (especially shear force, glass transition point, etc.) within a predetermined range.

[0178] That is, 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 beam curable acrylic adhesive composition.

[0179] Examples of the above active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron rays, or ultraviolet rays, and ultraviolet rays are particularly preferred. That is, the above active energy ray curing type adhesive composition is preferably an ultraviolet curing type adhesive composition.

[0180] Examples of adhesive compositions (acrylic adhesive compositions) forming the above acrylic adhesive layer include, for instance, an acrylic adhesive composition having an acrylic polymer as an essential component, or an acrylic adhesive composition having a mixture of monomers (which may be referred to as a "monomer mixture") constituting the acrylic polymer or a partial polymerization thereof as an essential component. Examples of the former include, for instance, so-called solvent-type acrylic adhesive compositions. Furthermore, examples of the latter include, for instance, so-called active energy beam-curing type acrylic adhesive compositions. The above "monomer mixture" refers to a mixture containing monomer components constituting a polymer. Furthermore, the above "partial polymerization" may be referred to as a "prepolymer" and refers to a composition in which one or more monomer components among the monomer components in the above monomer mixture are partially polymerized.

[0181] The above acrylic polymer is a polymer composed (formed) of an acrylic monomer as an essential monomer component. The above acrylic polymer is preferably a polymer composed (formed) of an alkyl (meth)acrylate ester as an essential monomer component. That is, the above acrylic polymer preferably includes an alkyl (meth)acrylate ester as a constituent unit. In this specification, "(meth)acrylate" refers to "acrylate" and / or "methacrylate" (either one or both of "acrylate" and "methacrylate"), and the same applies to others. Furthermore, the above acrylic polymer is composed of one or more monomer components.

[0182] As the above (meth)acrylate alkyl ester as an essential monomer component, (meth)acrylate alkyl esters having straight-chain or branched-chain alkyl groups are preferably cited. In addition, (meth)acrylate alkyl esters can be used alone or in combination of two or more types.

[0183] Alkyl esters of (meth)acrylate having a straight-chain or branched-chain alkyl group are not particularly limited, but include, for example, 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, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, and isodecyl (meth)acrylate. Examples include (meth)acrylate alkyl esters having a straight or branched alkyl group having 1 to 20 carbon atoms, such as (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, (meth)acrylate nonadecyl, and (meth)acrylate eicosyl. Among these, the (meth)acrylate alkyl ester having a straight-chain or branched-chain alkyl group is preferably a (meth)acrylate alkyl ester having a straight-chain or branched-chain alkyl group having 4 to 18 carbon atoms, and more preferably is 2-ethylhexyl acrylate (2EHA), isostearyl acrylate (ISTA), lauryl acrylate (LA), or butyl acrylate (BA). In addition, the (meth)acrylate alkyl ester having a straight-chain or branched-chain alkyl group may be used alone or in combination of two or more types.

[0184] The proportion of the (meth)acrylate alkyl ester in the total monomer component (100 weight%) constituting the acrylic polymer is not particularly limited, but is preferably 50 weight% or more (e.g., 50 to 100 weight%), more preferably 53 to 90 weight%, and even more preferably 55 to 85 weight%.

[0185] In addition, the acrylic adhesive composition may include the (meth)acrylate alkyl ester in addition to the acrylic polymer. When the acrylic adhesive composition contains the (meth)acrylate alkyl ester in addition to the acrylic polymer, the content (amount of formulation) of the (meth)acrylate alkyl ester is preferably 10 parts by weight or more (e.g., 10 to 100 parts by weight) with respect to 100 parts by weight of the acrylic polymer, more preferably 20 to 90 parts by weight, and even more preferably 30 to 80 parts by weight.

[0186] The above acrylic polymer may include a copolymerized monomer together with the (meth)acrylate alkyl ester as a monomer component constituting the polymer. That is, the above acrylic polymer may include a copolymerized monomer as a constituent unit. In addition, the copolymerized monomer may be used alone or in combination of two or more types.

[0187] As for the copolymerized monomers mentioned above, although not particularly limited, monomers having nitrogen atoms within the molecule and monomers having hydroxyl groups within the molecule are preferably cited from the perspective of ease of controlling the various properties of the adhesive layer (particularly shear force, glass transition point, etc.) within a predetermined range, suppression of cloudiness under high humidity environments and improvement of durability, adhesive reliability, compatibility with various additives such as UV absorbers, and transparency. That is, it is preferable that the acrylic polymer includes a monomer having nitrogen atoms within the molecule as a constituent unit. Furthermore, it is preferable that the acrylic polymer includes a monomer having hydroxyl groups within the molecule as a constituent unit.

[0188] The monomer having a nitrogen atom within the molecule is a monomer (monomer) having at least one nitrogen atom within the molecule (within one molecule). In this specification, the "monomer having a nitrogen atom within the molecule" may be referred to as a "nitrogen atom-containing monomer." The nitrogen atom-containing monomer is not particularly limited, but cyclic nitrogen-containing monomers, (meth)acrylamides, etc. are preferably cited. Additionally, the nitrogen atom-containing monomer may be used alone or in combination of two or more types.

[0189] 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 also has a cyclic nitrogen structure. It is preferable that the above-mentioned cyclic nitrogen structure has a nitrogen atom within the cyclic structure.

[0190] Examples of the above-mentioned cyclic nitrogen-containing monomers include N-vinyl cyclic amides (lactam-based vinyl monomers) and vinyl monomers having a nitrogen-containing heterocyclic group.

[0191] As for the above N-vinyl cyclic amide, for example, an N-vinyl cyclic amide represented by the following formula (1) can be cited.

[0192]

[0193] (In Equation (1), R 1 ...represents a divalent organic group)

[0194] R in the above equation (1) 1 It is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (e.g., an alkylene group having 3 to 5 carbon atoms).

[0195] Examples of N-vinyl cyclic amides represented by the above formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholindione, etc.

[0196] Examples of vinyl monomers having nitrogen-containing heterocyclic rings include, for instance, acrylic monomers having nitrogen-containing heterocyclic rings such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings.

[0197] The vinyl monomer having the above nitrogen-containing heterocyclic group is not particularly limited, but examples include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisooxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine, etc.

[0198] Among the above vinyl monomers having a nitrogen-containing heterocyclic group, an acrylic monomer having a nitrogen-containing heterocyclic group is preferred, and more preferably, (meth)acryloylmorpholine, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine.

[0199] Examples of the above (meth)acrylamides include (meth)acrylamide, N-alkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, etc. Examples of the above N-alkyl (meth)acrylamides include N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nn-butyl (meth)acrylamide, N-octyl (meth)acrylamide, etc. Additionally, the above N-alkyl (meth)acrylamides include (meth)acrylamides having amino groups such as dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide. Examples of the above N,N-dialkyl(meth)acrylamide 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, N,N-di(t-butyl)(meth)acrylamide, etc.

[0200] In addition, the above (meth)acrylamides include, for example, various N-hydroxyalkyl (meth)acrylamides. Examples of the above 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, N-methyl-N-2-hydroxyethyl (meth)acrylamide, etc.

[0201] In addition, the above (meth)acrylamides include, for example, various N-alkoxyalkyl (meth)acrylamides. Examples of the above N-alkoxyalkyl (meth)acrylamides include N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, etc.

[0202] In addition, examples of the above-mentioned cyclic nitrogen-containing monomers and nitrogen atom-containing monomers other than the above-mentioned (meth)acrylamides include amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, isocyanate group-containing monomers, etc. Examples of the above-mentioned amino group-containing monomers include (meth)acrylate aminoethyl, (meth)acrylate dimethylaminoethyl, (meth)acrylate dimethylaminopropyl, (meth)acrylate t-butylaminoethyl, etc. Examples of the above-mentioned cyano group-containing monomers include acrylonitrile, methacrylonitrile, etc. Examples of the above imide group-containing monomers include maleimide-based monomers (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide-based monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide, etc.), and succinimide-based monomers (e.g., N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc.). Examples of the above isocyanate group-containing monomers include 2-(meth)acryloyloxyethyl isocyanate.

[0203] Among these, as the nitrogen atom-containing monomer, a cyclic nitrogen-containing monomer is preferred, and an N-vinyl cyclic amide is more preferred. More specifically, N-vinyl-2-pyrrolidone (NVP) is particularly preferred.

[0204] 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 component (100 weight%) constituting the acrylic polymer is not particularly limited, but is preferably 1 weight% or more, more preferably 3 weight% or more, and even more preferably 5 weight% or more. If the proportion is 1 weight% or more, it is desirable because the suppression of cloudiness under high humidity environments and durability are further improved, and high adhesive reliability can be obtained. In addition, the upper limit of the proportion of the nitrogen atom-containing monomer is preferably 30 weight% or less, more preferably 25 weight% or less, and even more preferably 20 weight% or less, from the perspective of obtaining an adhesive layer with appropriate flexibility, obtaining an adhesive layer with excellent transparency, and making it easy to control the various characteristics of the adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range.

[0205] The monomer having a hydroxyl group within the molecule is preferably a monomer having at least one hydroxyl group within the molecule (within one molecule), having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and also having a hydroxyl group. However, the monomer having a hydroxyl group within the molecule does not include the nitrogen atom-containing monomer. That is, in this specification, a monomer having both a nitrogen atom and a hydroxyl group within the molecule is included in the "nitrogen atom-containing monomer." In this specification, the "monomer having a hydroxyl group within the molecule" may be referred to as a "hydroxyl group-containing monomer." Furthermore, the hydroxyl group-containing monomer may be used alone or in combination of two or more types.

[0206] Examples of the above hydroxyl group-containing monomers include hydroxyl group-containing (meth)acrylic acid esters such as (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid hydroxyoctyl, (meth)acrylic acid hydroxydecyl, (meth)acrylic acid hydroxylauryl, (meth)acrylic acid (4-hydroxymethylcyclohexyl); vinyl alcohol; allyl alcohol, etc.

[0207] Among these, the above hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylic acid ester, and more preferably 2-hydroxyethyl acrylic acid (HEA) or 4-hydroxybutyl acrylic acid (4HBA).

[0208] When the above acrylic polymer contains the above hydroxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the above hydroxyl group-containing monomer in the total monomer component (100 weight%) constituting the above acrylic polymer is not particularly limited, but it is preferable that it be 0.5 weight% or more, more preferably 0.8 weight% or more, and even more preferably 1 weight% or more in terms of suppressing cloudiness under high humidity environments, improving durability, and obtaining high adhesive reliability. In addition, the upper limit of the proportion of the above hydroxyl group-containing monomer is preferably 30 weight% or less, more preferably 25 weight% or less, and even more preferably 20 weight% or less in terms of making it easier to control the above various characteristics of the adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range.

[0209] In addition, for the purpose of further enhancing the above effect by the hydroxyl group-containing monomer, the acrylic adhesive composition may include a hydroxyl group-containing monomer in addition to the acrylic polymer. When the acrylic adhesive composition includes a hydroxyl group-containing monomer in addition to the acrylic polymer, the content (amount of blending) of the said 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. If the content is 5 parts by weight or more, the suppression of cloudiness under high humidity environments and durability are further improved, and higher adhesive reliability can be obtained, which is desirable. In addition, the upper limit of the content (formulation amount) of the above-mentioned hydroxyl group-containing monomer is 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 perspective of ease of obtaining cohesiveness, adhesion, and adhesion reliability, and ease of controlling the above-mentioned various characteristics of the adhesive layer (especially shear force, glass transition point, etc.) within a predetermined range.

[0210] The sum of the ratios of the nitrogen atom-containing monomer and the hydroxyl group-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but it is preferable to be 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more in terms of suppressing cloudiness in high-humidity environments, improving durability, and obtaining high adhesive reliability. In addition, the upper limit of the sum of the above ratios is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less, in terms of obtaining an adhesive layer with appropriate flexibility, obtaining an adhesive layer with excellent transparency, and making it easy to control the various characteristics of the adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range.

[0211] Cosynthetic monomers other than nitrogen atom-containing monomers and hydroxyl group-containing monomers may also include monomers containing a ring structure. The above-mentioned monomers containing a ring structure 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 ring structure. For example, alkyl (meth)acrylates having a cycloalkyl group are included in the above-mentioned monomers containing a ring structure. In addition, monomers containing a ring structure may be used alone or in combination of two or more types.

[0212] The alicyclic structure in the above-mentioned monomer containing alicyclic structure 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.

[0213] Examples of monomers containing the above-mentioned cyclic structure include (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate, dicyclofentanyl (meth)acrylate, HPMPA represented by the following formula (2), TMA-2 represented by the following formula (3), and HCPA represented by the following formula (4). In addition, in the following formula (4), the bonding sites of the cyclohexyl ring connected by a line and the structural formula within parentheses are not particularly limited. Among these, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferred.

[0214]

[0215]

[0216]

[0217] When the above acrylic polymer contains the above-mentioned cyclic structure-containing monomer as a monomer component constituting the polymer, the proportion of the above-mentioned cyclic structure-containing monomer in the total monomer component (100 weight%) constituting the above-mentioned acrylic polymer is not particularly limited, but it is preferable that it be 10 weight% or more in terms of improving durability and obtaining high adhesive reliability. In addition, the upper limit of the proportion of the above-mentioned cyclic structure-containing monomer is preferably 50 weight% or less, more preferably 40 weight% or less, and even more preferably 30 weight% or less, in terms of obtaining an adhesive layer having appropriate flexibility and making it easy to control the above-mentioned various characteristics of the adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range.

[0218] In addition, as copolymer monomers, polyfunctional monomers may be cited, for example. Examples of the 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, urethane acrylate, etc. In addition, polyfunctional monomers can be used alone or in combination of two or more types.

[0219] When the above acrylic polymer contains the above polyfunctional monomer as a monomer component constituting the polymer, the proportion of the above polyfunctional monomer in the total monomer component (100 weight%) constituting the above acrylic polymer is not particularly limited, but from the viewpoint of being easy to control the above various characteristics of the adhesive layer (especially shear force, glass transition point, etc.) to a predetermined range, it is preferably 0.5 weight% or less (e.g., greater than 0 weight% and 0.5 weight% or less), and more preferably 0.2 weight% or less (e.g., greater than 0 weight% and 0.2 weight% or less).

[0220] In addition, the above-mentioned polyfunctional monomer may be added to the above-mentioned acrylic polymer and incorporated into the acrylic adhesive composition. When the acrylic adhesive composition contains a polyfunctional monomer in addition to the acrylic polymer, the content (amount incorporated) of the said polyfunctional monomer is preferably 0.5 parts by weight or less (e.g., exceeding 0 parts by weight and 0.5 parts by weight or less) with respect to 100 parts by weight of the acrylic polymer, from the perspective of making it easier to control the above-mentioned various properties of the adhesive layer (particularly shear force, glass transition point, etc.) within a predetermined range, and more preferably 0.2 parts by weight or less (e.g., exceeding 0 parts by weight and 0.2 parts by weight or less).

[0221] In addition, the copolymer monomer mentioned above may be an alkoxyalkyl ester of (meth)acrylate. The alkoxyalkyl ester mentioned above is not particularly limited, but 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, 4-ethoxybutyl (meth)acrylate, etc. Among these, the alkoxyalkyl ester mentioned above is preferably an alkoxyalkyl ester of acrylic acid, and more preferably 2-methoxyethyl (MEA) of acrylic acid. In addition, the alkoxyalkyl ester mentioned above may be used alone or in combination of two or more types.

[0222] When the above acrylic polymer includes the (meth)acrylic acid alkoxyalkyl ester as a monomer component constituting the polymer, the ratio of the (meth)acrylic acid alkyl ester to the (meth)acrylic acid alkoxyalkyl ester is not particularly limited, but [the former:the latter] (weight ratio) is preferably greater than 100:0 and less than or equal to 25:75, and more preferably greater than 100:0 and less than or equal to 50:50.

[0223] In addition, the copolymerized monomers mentioned above may include, for example, monomers containing carboxyl groups, monomers containing epoxy groups, monomers containing sulfonic acid groups, monomers containing phosphate groups, (meth)acrylic acid esters having aromatic hydrocarbon groups, vinyl esters, aromatic vinyl compounds, olefins or dienes, vinyl ethers, vinyl chloride, etc. Examples of the monomers containing carboxyl groups may include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. Furthermore, the monomers containing carboxyl groups may include monomers containing acid anhydrides, such as maleic anhydride and itaconic anhydride. Examples of the monomers containing epoxy groups may include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of the monomers containing sulfonic acid groups may include sodium vinylsulfonate. Examples of monomers containing phosphate groups include 2-hydroxyethylacryloyl phosphate. Examples of (meth)acrylic acid esters having the aromatic hydrocarbon group include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, 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 vinyl ethers include vinylalkyl ethers.

[0224] In order to obtain an acrylic adhesive layer having excellent corrosion resistance, the above acrylic polymer preferably does not contain or substantially does not contain acid group-containing monomers as monomer components constituting the polymer, and in particular, it is preferable not to contain or substantially does not contain carboxyl group-containing monomers. Examples of acid group-containing monomers include carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, etc. Specifically, it can be said that the above acrylic polymer does not substantially contain an acid group-containing monomer in which the ratio of the acid group-containing monomer in the total monomer components (100 weight%) constituting the above acrylic polymer is 0.05 weight% or less (preferably 0.01 weight% or less).

[0225] The content of the base polymer (particularly an 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 to 100% by weight) with respect to 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 to 100% by weight), and even more preferably 90% by weight or more (e.g., 90 to 100% by weight).

[0226] The weight average molecular weight (Mw) of the above acrylic polymer is 100,000 to 500,000, preferably 500,000 to 400,000, and more preferably 750,000 to 300,000. A configuration in which the weight average molecular weight of the acrylic polymer is 100,000 or more is preferred in that the adhesive strength is improved and the anti-foaming peelability is improved. On the other hand, a configuration in which the weight average molecular weight of the acrylic polymer is 500,000 or less is preferred in that it is easy to increase the adhesive strength and the anti-foaming peelability is improved.

[0227] The weight average molecular weight (Mw) of the above acrylic polymer can be obtained by converting it to polystyrene using the GPC method. For example, it can be measured under the following conditions using the high-speed GPC device “HPLC-8120GPC” manufactured by Tosho Co., Ltd.

[0228] Column: TSKgel SuperHZM-H / HZ4000 / HZ3000 / HZ2000

[0229] Solvent: Tetrahydrofuran

[0230] Flow rate: 0.6 ml / min

[0231] The glass transition temperature (Tg) of the 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. If the glass transition temperature of the acrylic polymer is -70°C or higher, the cohesive strength is improved and the resistance to foaming and peeling is easily improved, which is desirable. Furthermore, a configuration in which the glass transition temperature of the acrylic polymer is -10°C or lower is desirable in that the stress relaxation properties of the adhesive layer are maintained even under low-temperature environments, allowing the adhesive layer to sufficiently follow shrinkage or expansion under the usage environment of the image display device of the present invention, thereby suppressing lifting or peeling and ensuring sufficient adhesion to the substrate.

[0232] The glass transition temperature (Tg) of the above acrylic polymer is the glass transition temperature (theoretical value) expressed by the following FOX formula.

[0233] 1 / Tg=W1 / Tg1+W2 / Tg2+… +W n / Tg n

[0234] In the above formula, Tg is the glass transition temperature of the acrylic polymer (unit: K), Tg i θ is the glass transition temperature when monomer i forms a homopolymer (unit: K), W irepresents the weight fraction of monomer i in the total amount of monomer components (i=1, 2, ····n).

[0235] As the homopolymer Tg of the monomer constituting the above acrylic polymer, the following values ​​may be adopted.

[0236] 2-Ethylhexyl Acrylate -70℃

[0237] n-hexyl acrylate -65℃

[0238] n-Octyl Acrylate -65℃

[0239] Isononyl acrylate -60℃

[0240] n-nonyl acrylate -58℃

[0241] n-butyl acrylate -55℃

[0242] Ethyl acrylate -20℃

[0243] Lauryl acrylate 0℃

[0244] 2-ethylhexyl methacrylate -10℃

[0245] Methyl acrylate 8℃

[0246] n-butyl methacrylate 20℃

[0247] Methyl methacrylate 105℃

[0248] Acrylic acid 106℃

[0249] Methacryl acid 228℃

[0250] Vinyl acetate 32℃

[0251] Styrene 100℃

[0252] In addition, for the homopolymer Tg of monomers not listed above, the values ​​listed in the “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc, 1989) may be used. In addition, for the homopolymer Tg of monomers not listed in the above literature, the values ​​obtained by the measurement method described above (the peak top temperature of tanδ by viscoelasticity test) may be used.

[0253] The base polymer, such as the acrylic polymer, contained in the adhesive layer of the present invention is obtained by polymerizing the monomer component. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by irradiation with active energy rays (active energy ray polymerization method). Among these, the solution polymerization method and the active energy ray polymerization method are preferred in terms of the transparency of the adhesive layer and cost, and the active energy ray polymerization method is more preferred.

[0254] In addition, various general solvents may be used during the polymerization of the above monomer components. Examples of the above solvents include organic solvents such as esters like ethyl acetate and n-butyl acetate; aromatic hydrocarbons like toluene and benzene; aliphatic hydrocarbons like n-hexane and n-heptane; alicyclic hydrocarbons like cyclohexane and methylcyclohexane; and ketones like methyl ethyl ketone and methyl isobutyl ketone. Furthermore, the solvents may be used alone or in combination of two or more types.

[0255] When polymerizing the above monomer components, polymerization initiators such as thermal polymerization initiators or photopolymerization initiators (photoinitiators) may be used depending on the type of polymerization reaction. In addition, polymerization initiators may be used alone or in combination of two or more types.

[0256] The above thermal polymerization initiator is not particularly limited, but examples include azo-based polymerization initiators, peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), redox-based polymerization initiators, etc. Among these, the azo-based polymerization initiator disclosed in Japanese Patent Publication No. 2002-69411 is preferred. Examples of the above azo-based polymerization initiator include 2,2'-azobis-isobutyronitrile (hereinafter referred to as "AIBN"), 2,2'-azobis-2-methylbutyronitrile (hereinafter referred to as "AMBN"), 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, etc. Additionally, the thermal polymerization initiator may be used alone or in combination of two or more types.

[0257] When the azo polymerization initiator is used during the polymerization of the 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, more preferably 0.3 parts by weight or less, based on 100 parts by weight of the total monomer component constituting the acrylic polymer.

[0258] The above 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, thioxanthone-based photopolymerization initiators, etc. In addition, acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators may be used. 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, anisole methyl ether, etc. Examples of the above-mentioned acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloroacetophenone, etc. Examples of the above α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, etc. Examples of the above aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride, etc. Examples of the above photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime, etc. Examples of the above benzoin-based photopolymerization initiators include benzoin, etc. Examples of the above benzyl-based photopolymerization initiators include benzyl, etc. Examples of the above benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, etc. Examples of the above ketal-based photopolymerization initiators include benzyldimethylketal, etc.Examples of the above thioxantone-based photopolymerization initiators include thioxantone, 2-chlorothioxantone, 2-methylthioxantone, 2,4-dimethylthioxantone, isopropylthioxantone, 2,4-diisopropylthioxantone, dodecylthioxantone, etc. Examples of the above acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. Examples of the above 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. Additionally, photopolymerization initiators can be used alone or in combination of two or more types.

[0259] When the photopolymerization initiator is used during the polymerization of the above 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 per 100 parts by weight of the total monomer component constituting the acrylic polymer, more preferably 0.1 parts by weight or more, and also preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less.

[0260] 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. When an acrylic oligomer is contained, the adhesion to the substrate at the interface in the optical adhesive tape of the present invention is improved, making it easier to obtain strong adhesion and also making it easier to obtain excellent anti-foaming peelability. In addition, in this specification, "an acrylic oligomer having a weight average molecular weight of 1,000 to 30,000" may be simply referred to as "an acrylic oligomer."

[0261] As the above acrylic oligomer, an acrylic polymer composed of a (meth)acrylic acid ester having a cyclic structure within the molecule as an essential monomer component is preferably cited, and an acrylic polymer composed of a (meth)acrylic acid ester having a cyclic structure within the molecule and an (meth)acrylic acid alkyl ester having a straight-chain or branched-chain alkyl group as an essential monomer component is more preferably cited. That is, as the above acrylic oligomer, an acrylic polymer comprising a (meth)acrylic acid ester having a cyclic structure within the molecule as a monomer unit is preferably cited, and an acrylic polymer comprising a (meth)acrylic acid ester having a cyclic structure within the molecule and an (meth)acrylic acid alkyl ester having a straight-chain or branched-chain alkyl group as a monomer unit is more preferably cited.

[0262] The cyclic structure (ring) of the (meth)acrylic acid ester having a cyclic structure within the above molecule (in one molecule) (hereinafter 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 above aromatic ring include an aromatic carbon ring [e.g., a monocyclic carbon ring such as a benzene ring, or a condensed carbon ring such as a naphthalene ring], various aromatic heterocyclic rings, etc. Examples of the above non-aromatic ring include a non-aromatic aliphatic ring (non-aromatic alicyclic ring) [e.g., a cycloalkane ring such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, or a cyclooctane ring; Examples include cycloalkene rings such as cyclohexene rings, non-aromatic crosslinks [e.g., bicyclic hydrocarbon rings in pinan, pinene, bornan, norbornan, norbornene, etc.; aliphatic hydrocarbon rings of three or more rings (crosslinked hydrocarbon rings) in adamantane, etc.], and non-aromatic heterocyclic rings [e.g., epoxy rings, oxolan rings, oxetane rings, etc.].

[0263] Examples of the above three or more aliphatic hydrocarbon rings (three or more cross-linked hydrocarbon rings) include, for instance, a dicyclofentanyl group represented by the following formula (5a), a dicyclofentenyl group represented by the following formula (5b), an adamantyl group represented by the following formula (5c), a tricyclofentanyl group represented by the following formula (5d), and a tricyclofentenyl group represented by the following formula (5e).

[0264]

[0265] That is, the above-mentioned ring-containing (meth)acrylic acid esters include, for example, cycloalkyl esters of (meth)acrylic acid such as cyclopentyl (meth)acrylic acid, cyclohexyl (meth)acrylic acid, cycloheptyl (meth)acrylic acid, and cyclooctyl (meth)acrylic acid; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylic acid; and (meth)acrylic acid esters having three or more rings of aliphatic hydrocarbon ring such as dicyclofentanyl (meth)acrylate, dicyclofentanyloxyethyl (meth)acrylate, tricyclofentanyl (meth)acrylate, 1-adamanthyl (meth)acrylate, 2-methyl-2-adamanthyl (meth)acrylate, and 2-ethyl-2-adamanthyl (meth)acrylate. Examples include (meth)acrylic acid esters having an aromatic ring, such as aryl meth)acrylic acid esters such as phenyl (meth)acrylate, aryloxyalkyl meth)acrylic acid esters such as phenoxyethyl (meth)acrylate, and arylalkyl meth)acrylic acid esters such as benzyl (meth)acrylate. Among these, as the above ring-containing (meth)acrylic acid esters, non-aromatic ring-containing (meth)acrylic acid esters are particularly preferred, more preferably cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), dicyclofentanyl acrylate (DCPA), and dicyclofentanyl methacrylate (DCPMA), and even more preferably dicyclofentanyl acrylate (DCPA) and dicyclofentanyl methacrylate (DCPMA). In addition, ring-containing (meth)acrylic acid esters may be used alone or in combination of two or more types.

[0266] Among the above non-aromatic ring-containing (meth)acrylic acid esters, when using a (meth)acrylic acid ester having three or more aliphatic hydrocarbon rings (especially three or more cross-linked hydrocarbon rings), it is particularly preferred in that it is difficult to cause polymerization inhibition. In addition, when using a (meth)acrylic acid ester having a dicyclofentanyl group represented by formula (5a) that does not have unsaturated bonds, an adamantyl group represented by formula (5c), or a tricyclofentanyl group represented by formula (5d), the anti-foaming peelability can be further increased, and the adhesion to low-polarity substrates such as polyethylene or polypropylene can be significantly improved.

[0267] The content (ratio) of the above-mentioned ring-containing (meth)acrylic acid ester in the total monomer unit of the acrylic oligomer (the 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 with respect to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). If the content of the above-mentioned ring-containing (meth)acrylic acid ester is 10 parts by weight or more, it is desirable for the anti-foaming peelability to be easily improved. In addition, if the content is 90 parts by weight or less, the adhesive layer has appropriate flexibility, and the adhesive strength and step absorption properties to be easily improved, which is desirable.

[0268] In addition, as (meth)acrylate alkyl esters having the straight-chain or branched-chain alkyl group as monomer units of the acrylic oligomer, examples include (meth)acrylate 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 2-ethylhexyl, (meth)acrylate isooctyl, (meth)acrylate nonyl, (meth)acrylate isononyl, (meth)acrylate decyl, (meth)acrylate isodecyl. Examples include alkyl esters of (meth)acrylate having 1 to 20 carbon atoms in an alkyl group, such as (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, and (meth)acrylate eicosyl. Among these, methyl methacrylate (MMA) is preferred because it exhibits good compatibility with acrylic polymers. Additionally, the above alkyl esters of (meth)acrylate may be used alone or in combination of two or more types.

[0269] The content (ratio) of the (meth)acrylate alkyl ester having a straight-chain or branched-chain alkyl group in the total monomer unit of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but in terms of anti-foaming peelability, it is preferably 10 to 90 parts by weight with respect to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight), more preferably 20 to 80 parts by weight, and even more preferably 20 to 60 parts by weight. If the content is 10 parts by weight or more, it is particularly desirable as it facilitates the improvement of adhesion to substrates made of acrylic resin or polycarbonate.

[0270] As monomer units of the acrylic oligomer, in addition to the above-mentioned ring-containing (meth)acrylic acid esters and (meth)acrylic acid alkyl esters having straight-chain or branched-chain alkyl groups, monomers capable of copolymerizing with these monomers (copolymerizable monomers) may also be included. Furthermore, the content (ratio) of the copolymerizable monomer in the total monomer units of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but it is preferably 49.9 parts by weight or less (e.g., 0 to 49.9 parts by weight) with respect to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight), and more preferably 30 parts by weight or less. In addition, copolymerizable monomers may be used alone or in combination of two or more types.

[0271] As the copolymerized monomer as a monomer unit of the acrylic oligomer (the copolymerized monomer constituting the acrylic oligomer), for example, (meth)acrylate alkoxyalkyl ester [e.g., (meth)acrylate 2-methoxyethyl, (meth)acrylate 2-ethoxyethyl, (meth)acrylate methoxytriethylene glycol, (meth)acrylate 3-methoxypropyl, (meth)acrylate 3-ethoxypropyl, (meth)acrylate 4-methoxybutyl, (meth)acrylate 4-ethoxybutyl, etc.]; Monomers containing a hydroxyl group [e.g., hydroxyalkyl (meth)acrylates such as (meth)acrylate 2-hydroxyethyl, (meth)acrylate 2-hydroxypropyl, (meth)acrylate 2-hydroxybutyl, (meth)acrylate 3-hydroxypropyl, (meth)acrylate 4-hydroxybutyl, (meth)acrylate 6-hydroxyhexyl, vinyl alcohol, allyl alcohol, etc.]; monomers containing an amide group [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.]; Examples include amino group-containing monomers [e.g., (meth)acrylate aminoethyl, (meth)acrylate dimethylaminoethyl, (meth)acrylate t-butylaminoethyl, etc.]; cyano group-containing monomers [e.g., acrylonitrile, methacrylonitrile, etc.]; sulfonic acid group-containing monomers [e.g., sodium vinylsulfonate, etc.]; phosphate group-containing monomers [e.g., 2-hydroxyethylacryloylphosphate, etc.]; isocyanate group-containing monomers [e.g., 2-methacryloyloxyethylisocyanate, etc.]; imide group-containing monomers [cyclohexylmaleimide, isopropylmaleimide, etc.].

[0272] As described above, the acrylic oligomer is preferably an acrylic polymer comprising, as monomer units, a (meth)acrylic acid ester having a cyclic structure within the molecule and an (meth)acrylic acid alkyl ester having a straight-chain or branched-chain alkyl group. Among these, it is preferable that the acrylic polymer comprises, as monomer units, a ring-containing (meth)acrylic acid ester and the above-mentioned (meth)acrylic acid alkyl ester having a straight-chain or branched-chain alkyl group. In the acrylic polymer comprising, as monomer units, a ring-containing (meth)acrylic acid ester and an (meth)acrylic acid alkyl ester having a straight-chain or branched-chain alkyl group, the amount of the ring-containing (meth)acrylic acid 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, and more preferably 20 to 80 parts by weight. In addition, the content of (meth)acrylate alkyl ester having a straight-chain or branched-chain 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.

[0273] In addition, a particularly preferred specific composition of the acrylic oligomer may include, as monomer units, an acrylic polymer comprising (1) at least one monomer selected from the group consisting of dicyclofentanyl acrylate, dicyclofentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate, and (2) methyl methacrylate. In the acrylic oligomer of the particularly preferred specific composition above, it is preferable that the content of (1) dicyclofentanyl acrylate, dicyclofentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate (the total amount if two or more are included) among the total monomer units of the acrylic oligomer is 30 to 70 parts by weight, and (2) the content of methyl methacrylate is 30 to 70 parts by weight, relative to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight). However, the acrylic oligomer is not limited to the specific composition above.

[0274] The acrylic oligomer can be obtained by polymerizing the above monomer component by a known or conventional polymerization method. Examples of polymerization methods for the acrylic oligomer include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy irradiation (active energy irradiation method). Among these, bulk polymerization and solution polymerization methods are preferred, and more preferably, solution polymerization is preferred.

[0275] When polymerizing acrylic oligomers, various general solvents may be used. 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. In addition, these solvents may be used alone or in combination of two or more types.

[0276] In addition, when polymerizing acrylic oligomers, known or conventional polymerization initiators (e.g., thermal polymerization initiators or photopolymerization initiators) may be used. In addition, polymerization initiators may be used alone or in combination of two or more types.

[0277] As a thermal polymerization initiator, for example, an azo-based initiator such as 2,2'-azobis-isobutyronitrile (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), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane); Examples of peroxide-based initiators include 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. Additionally, 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 types.

[0278] The amount of the above thermal polymerization initiator used is not particularly limited, but, for example, 0.1 to 15 parts by weight per 100 parts by weight of the total monomer unit of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer).

[0279] In addition, the above photopolymerization initiator is not particularly limited, but may be, for example, a photopolymerization initiator identical to the one used in the polymerization of the acrylic polymer exemplified above. The amount of the above photopolymerization initiator used is not particularly limited and is appropriately selected.

[0280] When polymerizing the above acrylic oligomer, 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 the above-mentioned 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, iso-octyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, thioglycolic acid ester of pentaerythritol, α-methylstyrene dimer, etc. Among these, α-thioglycerol and methyl thioglycolate are preferred, and α-thioglycerol is particularly preferred, from the perspective of suppressing whitening of the optical adhesive tape of the present invention due to humidification. In addition, the chain transfer agent may be used alone or in combination of two or more types.

[0281] The content (amount used) of the above 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 unit (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 polymer with a weight-average molecular weight controlled to 1,000 to 30,000 can be easily obtained.

[0282] 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 support properties are improved, and anti-foaming peelability is improved. On the other hand, since the weight average molecular weight of the acrylic oligomer is 30,000 or less, it is easy to increase adhesive strength and anti-foaming peelability is improved.

[0283] The weight average molecular weight (Mw) of the above acrylic oligomer can be obtained by converting it to polystyrene using the GPC method. For example, it can be measured under the following conditions using the high-speed GPC device “HPLC-8120GPC” manufactured by Toso Co., Ltd.

[0284] Column: TSKgel SuperHZM-H / HZ4000 / HZ3000 / HZ2000

[0285] Solvent: Tetrahydrofuran

[0286] Flow rate: 0.6 ml / min

[0287] 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. If the glass transition temperature of the acrylic oligomer is 20°C or higher, it is preferable because the anti-foaming peelability is easily improved. In addition, if the glass transition temperature of the acrylic oligomer is 300°C or lower, it is preferable because the adhesive layer has appropriate flexibility, it is easy to obtain good adhesive strength or good step absorption, and it is easy to obtain excellent adhesive reliability.

[0288] The glass transition temperature (Tg) of the above acrylic oligomer is the glass transition temperature (theoretical value) expressed by the above FOX formula.

[0289] As the homopolymer Tg of the monomer constituting the above acrylic oligomer, the values ​​listed in Table 1 below may be used. Additionally, as the homopolymer Tg of the monomer not listed in Table 1, the values ​​listed in the “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc, 1989) may be used. Additionally, as the homopolymer Tg of the monomer not listed in the above literature, the value obtained by the measurement method described above (the peak top temperature of tanδ by viscoelasticity test) may be used.

[0290]

[0291] In addition, the copolymer of “DCPMA / MMA=60 / 40” in Table 1 refers to a copolymer of 60 parts by weight of DCPMA and 40 parts by weight of MMA.

[0292] 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, based on 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, based on 100 parts by weight of the total monomer unit 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, based on 100 parts by weight of the monomer mixture. It is desirable that the content of the acrylic oligomer be 1 part by weight or more, as this makes it easier to obtain excellent adhesion and excellent anti-foaming peelability. Additionally, it is desirable that the content of the acrylic oligomer be 30 parts by weight or less, as this makes it easier to obtain excellent transparency and adhesive reliability. Furthermore, from the perspective of making it easier to control the various characteristics of the adhesive layer (particularly shear force, glass transition point, etc.) within a predetermined range, the content of the acrylic oligomer is preferably 10 parts by weight or less, and more preferably 8 parts by weight or less.

[0293] The method for preparing the above adhesive composition containing an acrylic polymer and an acrylic oligomer is not particularly limited. For example, it is prepared by adding an acrylic oligomer, additives, etc., as needed to a mixture of monomer components constituting an acrylic polymer or a partial polymer of a mixture of monomer components constituting an acrylic polymer (a monomer mixture forming an acrylic polymer or a partial polymer thereof) and mixing them.

[0294] The adhesive layer of the present invention is not particularly limited, but it is preferable that it contains an ultraviolet absorber (UVA). It is preferable that the adhesive layer of the present invention contains an ultraviolet absorber in that it can suppress damage to the image display panel caused by ultraviolet rays. In addition, the ultraviolet absorber may be used alone or in combination of two or more types.

[0295] The above-mentioned ultraviolet absorbers are not particularly limited, but examples include benzotriazole-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, etc.

[0296] Benzotriazole-based UV absorbers (benzotriazole compounds) include, for example, 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), ester compounds of benzenepropanoic acid and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side-chain and straight-chain 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 109", BASF), 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900", BASF), 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", BASF), and methyl 3-(3-(2H-benzotriazole-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 Product (trade name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazole-2-yl)-p-cresol (trade name "TINUVIN P", manufactured by BASF), 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazole-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol](trade name "TINUVIN 360",Reaction product of methyl 3-(3-(2H-benzotriazole-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213", BASF), 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb 250", Sumitomo Chemical Corporation), 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-tert-octylphenol] (trade name "Adecastab LA-31", Examples include ADEKA Co., Ltd., etc.

[0297] As hydroxyphenyltriazine-based UV absorbers (hydroxyphenyltriazine-based compounds), examples 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 405」, manufactured by BASF), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name "Adecastab LA-46", manufactured by ADEKA Inc.), Examples include 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (product name “TINUVIN 479”, manufactured by BASF). In addition, a compound represented by the following formula (6) (product name “TINUVIN 477”, manufactured by BASF) can be cited.

[0298]

[0299] Benzophenone-based UV absorbers (benzophenone compounds) and oxybenzophenone-based UV absorbers (oxybenzophenone compounds) include, for example, 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 Kasei Co., Ltd.), and 2,2',4,4'-tetrahydroxybenzophenone (trade name "SEESORB 106", Cipro Examples include 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, etc. (manufactured by Kasei Co., Ltd.).

[0300] As salicylic acid ester-based ultraviolet absorbers (salicylic acid ester-based compounds), for example, 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, Examples include 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (product name "TINUVIN 120", manufactured by BASF).

[0301] Examples of cyanoacrylate-based ultraviolet absorbers (cyanoacrylate-based compounds) include alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, etc.

[0302] As the above-mentioned ultraviolet absorber, at least one ultraviolet absorber selected from the group consisting of benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and hydroxyphenyltriazine-based ultraviolet absorbers is preferred, in that it has high ultraviolet absorption, further improves corrosion resistance (especially UV resistance), excellent optical properties, is easy to obtain an adhesive layer having high transparency, and has excellent photostability, and benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers are more preferred. In particular, a benzotriazole-based ultraviolet absorber is preferred in which a phenyl group having a group having 6 or more carbon atoms and a hydroxyl group as a substituent is bonded to a nitrogen atom constituting a benzotriazole ring.

[0303] In addition, the above-mentioned UV absorber is preferably such that the absorbance A obtained below is 0.5 or less, in order to obtain higher UV absorption and further improve corrosion resistance (especially UV resistance).

[0304] Absorbance A: Absorbance measured by irradiating a 0.08% toluene solution of the above-mentioned UV absorber with light of a wavelength of 400 nm

[0305] When the adhesive layer of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber in the adhesive layer of the present invention (particularly an acrylic adhesive layer) is not particularly limited, but in order to further improve corrosion resistance (particularly UV resistance), it is preferable that it be 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. In addition, the upper limit of the content 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, in order to suppress the occurrence of yellowing of the adhesive accompanying the addition of the ultraviolet absorber and to obtain excellent optical properties, high transparency, and excellent appearance properties, in order to suppress the occurrence of yellowing of the adhesive accompanying the addition of the ultraviolet absorber.

[0306] The adhesive layer of the present invention may contain a light stabilizer. When the adhesive layer of the present invention contains a light stabilizer, it is particularly preferable to contain the light stabilizer together with the ultraviolet absorber. Since the light stabilizer can capture radicals generated from photo-oxidation, it can improve the resistance of the adhesive layer to light (especially ultraviolet light). In addition, the light stabilizer may be used alone or in combination of two or more types.

[0307] The above light stabilizers are not particularly limited, but examples include phenol-based light stabilizers (phenol compounds), phosphorus-based light stabilizers (phosphorus compounds), thioether-based light stabilizers (thioether compounds), amine-based light stabilizers (amine compounds) (particularly hindered amine-based stabilizers (hindered amine compounds)).

[0308] As the above-mentioned phenolic light stabilizer (phenolic compound), for example, 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)benzyl malonate, tocopherol, 2,2'-methylenebis(4-methyl-6-tertiary butylphenol), 2,2'-methylenebis(4-ethyl-6-tertiary butylphenol), 4,4'-methylenebis(2,6-di-tertiary butylphenol), 4,4'-butylidene bis(6-tertiary Butyl-m-cresol), 4,4'-Thiobis(6-tertiary butyl-m-cresol), styrenephenol, N,N'-hexamethylenebis(3,5-di-tertiary butyl-4-hydroxyhydrocinnaamide, bis(3,5-di-tertiary butyl-4-hydroxybenzylphosphonicate ethyl ester)calcium, 1,1,3-tris(2-methyl-4-hydroxy-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-cresol], 1,3,5-Tris(4-tertiary butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 1,3,5-Tris(3,5-di-tertiary butyl-4-hydroxybenzyl)isocyanuric acid, triethyleneglycol-bis[3-(3-tertiary butyl-4-hydroxy-5-methylphenyl)propionate], 2,2'-Oxamidebis[ethyl 3-(3,5-di-tertiary [Butyl-4-hydroxyphenyl)propionate], 6-(4-hydroxy-3,5-di-tertiary butylanilino)-2,4-dioctylthio-1,3,5-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,Examples include 1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 3,9-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, etc.

[0309] Phosphorus-based light stabilizers (phosphorus compounds) include, for example, trisnonylphenylphosphite, tris(2,4-di-tertiary butylphenyl)phosphite, tris[2-tertiary butyl-4-(3-tertiary butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecylphosphite, octyldiphenylphosphite, di(decyl)monophenylphosphite, 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, and bis(2,4,6-tri-tertiary Examples include 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)butanetriphosphite, tetrakis(2,4-di-tertiary butylphenyl)biphenylene diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and tris(2-[(2,4,8,10-tetrakis-tertiary butyldibenzo[d,f][1,3,2]dioxaphosphen-6-yl)oxy]ethyl)amine.

[0310] Examples of thioether-based light stabilizers (thioether-based compounds) include dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl, and distearyl; and β-alkylmercaptopropionate ester compounds of polyols such as tetrakis[methylene(3-dodecylthio)propionate]methane.

[0311] As amine-based light stabilizers (amine-based compounds), for example, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name "TINUVIN 622", manufactured by BASF), and a one-to-one reaction product of a polymer 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 119", manufactured by BASF), Polycondensate of 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 (trade 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} (trade name "TINUVIN 944", manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and Mixture of methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 765", BASF), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (trade name "TINUVIN 770", BASF), reaction product of bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) decanoate, 1,1-dimethylethylhydroperoxide, and octane (trade name "TINUVIN 123", BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (trade name "TINUVIN 144", BASF), The reaction product of cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidinamine-2,4,6-trichloro-1,3,5-triazine and the reaction product of 2-aminoethanol (trade name "TINUVIN 152", manufactured by BASF),Examples include a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate (product 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 (product name "AdekaStab LA-63P", manufactured by ADEKA Inc.). As for amine-based stabilizers, hindered amine-based stabilizers are particularly preferred.

[0312] 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, an acrylic adhesive layer) is not particularly limited, but in terms of making it easier to exhibit resistance to light, it is preferable that it be 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 addition, the upper limit of the 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 terms of optical properties, which makes it easier to obtain high transparency and prevents coloring by the light stabilizer itself.

[0313] In forming the adhesive layer of the present invention, a crosslinking agent may be used, although it is not particularly limited. For example, an acrylic polymer in an acrylic adhesive layer can be crosslinked to control the gel fraction. In addition, the crosslinking agent may be used alone or in combination of two or more types.

[0314] The above-mentioned crosslinking agent is 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, amine-based crosslinking agents, etc. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred, and more preferably, isocyanate-based crosslinking agents.

[0315] Examples of the above isocyanate-based crosslinking agents (polyfunctional isocyanate compounds) include, for instance, 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; aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylene diisocyanate. In addition, commercially available products such as trimethylolpropane / tolylene diisocyanate adduct (product name "Coronate L", manufactured by Nippon Polyurethane Kogyo Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate adduct (product name "Coronate HL", manufactured by Nippon Polyurethane Kogyo Co., Ltd.), and trimethylolpropane / xylylene diisocyanate adduct (product name "Takenate D-110N", manufactured by Mitsui Chemicals Co., Ltd.) may also be cited as the above-mentioned isocyanate-based crosslinking agent.

[0316] As the above epoxy-based crosslinking agent (polyfunctional epoxy compound), for example, N,N,N',N'-tetraglycidyl-m-xylenediamine, 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, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, Examples include triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in their molecules. In addition, commercially available products such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Corporation) may be used as the above-mentioned epoxy crosslinking agent.

[0317] 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 in terms of obtaining sufficient adhesive reliability, it is preferable that the amount be 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. In addition, 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, in terms of obtaining appropriate flexibility in the adhesive layer, improving adhesive strength, and making it easy to control the various characteristics of the adhesive layer (in particular, shear strength, glass transition point, etc.) within a predetermined range.

[0318] The adhesive layer of the present invention (particularly, an acrylic adhesive layer) may contain a silane coupling agent to improve adhesive reliability under humid conditions, particularly to improve adhesive reliability to glass. Additionally, the silane coupling agent may be used alone or in combination of two or more types. When the adhesive layer contains a silane coupling agent, adhesiveness under humid conditions, particularly adhesiveness to glass, can be improved.

[0319] The above silane coupling agent is not particularly limited, but examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, etc. Additionally, commercially available products such as the trade name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.) may be used as silane coupling agents. Among these, γ-glycidoxypropyltrimethoxysilane is preferred as the above silane coupling agent.

[0320] 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, an 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. In addition, 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.

[0321] The adhesive layer of the present invention may contain an antistatic agent. In addition, the antistatic agent may be used alone or in combination of two or more types. If the adhesive layer contains an antistatic agent, damage to the substrate, such as an image display panel, can be prevented.

[0322] Examples of the above antistatic agents include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, and first, second, and third amino groups; anionic antistatic agents having anionic functional groups such as sulfonates, sulfate esters, phosphonates, and phosphate esters; amphoteric antistatic agents such as alkyl betaines and their derivatives, imidazoline and its derivatives, alanine and its derivatives; nonionic antistatic agents such as amino alcohols and their derivatives, glycerin and its derivatives, polyethylene glycol and its derivatives; and furthermore, ionic conductive polymers obtained by polymerizing or copolymerizing monomers having cationic, anionic, and amphoteric ionic conductive groups.

[0323] When the adhesive layer of the present invention contains an antistatic agent, the content of the antistatic agent in the adhesive layer of the present invention 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. In addition, the upper limit of the content of the antistatic 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.

[0324] The adhesive layer of the present invention may contain a coloring agent. Additionally, the coloring agent may be used alone or in combination of two or more types. It is preferable that the adhesive layer contains a coloring agent in that it can prevent reflection caused by metal wiring or ITO wiring, etc., disposed on the substrate of the image display device of the present invention.

[0325] The above-mentioned coloring agent may be a dye or a pigment, provided that it is soluble or disperseable in the adhesive layer of the present invention. Dyes are preferred because they allow for low haze to be achieved with a small amount of addition and are easy to distribute uniformly without sedimentation, unlike pigments. Additionally, pigments are also preferred because they provide high color expression with a small amount of addition. When using a pigment as a coloring agent, it is preferable that it has low or no conductivity. Furthermore, when using a dye, it is preferable to use it in combination with the light stabilizer mentioned above.

[0326] As for the above-mentioned coloring agent, it may be used without limitation as long as it absorbs visible light (wavelength 400 to 700 nm) and exhibits transmittance to ultraviolet light (wavelength 330 to 400 nm) or absorbance to ultraviolet light, but it is preferable that it absorbs visible light and also has ultraviolet transmittance. That is, it is preferable that the above-mentioned coloring agent is a coloring agent in which the maximum transmittance value for a wavelength of 330 to 400 nm is greater than the maximum transmittance value for a wavelength of 400 to 700 nm. In addition, it is also preferable that the above-mentioned coloring agent has an average transmittance for a wavelength of 330 to 400 nm that is greater than the average transmittance for a wavelength of 400 to 700 nm. The transmittance of the coloring agent is measured using a solution or dispersion diluted with a suitable solvent such as tetrahydrofuran (THF) or a dispersion medium (an organic solvent with low absorption in the range of wavelengths 330 to 700 nm) so that the transmittance at a wavelength of 400 nm is about 50 to 60%.

[0327] Carbon black or titanium black, which are commonly used as black coloring agents, absorb ultraviolet light more than visible light (ultraviolet transmittance is lower than visible light transmittance). Therefore, when coloring agents such as carbon black are added to an active energy beam curing type acrylic adhesive composition, a large portion of the ultraviolet light irradiated for photocuring is absorbed by the coloring agent, so the amount of light absorbed by the photopolymerization initiator is small, and photocuring requires a long time (the total amount of irradiated light increases). In addition, when the thickness of the adhesive layer is large, the amount of ultraviolet light reaching the side opposite the irradiated surface is small, so photocuring tends to be insufficient even if light irradiation is performed for a long time. In contrast, by using a coloring agent that has a higher transmittance of ultraviolet light than visible light, the inhibition of curing caused by the coloring agent can be suppressed.

[0328] Examples of ultraviolet-transmitting black pigments include Tokushiki’s “9050BLACK” and “UVBK-0001”. Examples of ultraviolet-absorbing black dyes include Orient Kagaku Kogyo’s “VALIFAST BLACK 3810” and “NUBIAN Black PA-2802”. Examples of ultraviolet-absorbing black pigments include carbon black and titanium black.

[0329] The content of the coloring agent 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 according to the type of coloring agent, the color tone and light transmittance of the adhesive layer, etc. The coloring agent may be added to the composition as a solution or dispersion obtained by dissolving or dispersing in a suitable solvent.

[0330] The adhesive layer of the present invention may also, if necessary, contain additives such as crosslinking promoters, 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 the effects of the present invention are not impaired. In addition, these additives may be used alone or in combination of two or more types.

[0331] The haze of the adhesive layer of the present invention is not particularly limited, but in terms of appearance characteristics, transparency, and optical characteristics, it is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less. In addition, in this specification, the haze of the adhesive layer can be measured in accordance with JIS K 7136, for example, using a haze meter.

[0332] The total light transmittance of the adhesive layer of the present invention is not particularly limited, but in terms of appearance characteristics, transparency, and optical characteristics, it is preferably 85% or more, more preferably 90% or more, and even more preferably 92% or more. In addition, in this specification, the total light transmittance of the adhesive layer can be measured in accordance with JIS K 7361-1, for example, using a haze meter. Furthermore, the total light transmittance is the transmittance of light (visible light) with a wavelength of 400 to 780 nm.

[0333] The thickness of the adhesive layer of the present invention is not particularly limited, but is preferably 12 μm or more to obtain sufficient adhesive reliability, preferably 15 μm or more, more preferably 20 μm or more, and particularly preferably 70 μm or more. A thickness of 12 μm or more is preferred in that the adhesive layer sufficiently follows shrinkage or expansion under the usage environment of the image display device of the present invention, and can suppress lifting or peeling. In addition, the thickness is preferably 500 μm or less to obtain optical properties, preferably 300 μm or less, and more preferably 200 μm or less.

[0334] Manufacture of Optical Adhesive Tapes

[0335] The optical adhesive tape of the present invention can be prepared by laminating an adhesive layer of the present invention on a first surface of the substrate of the present invention.

[0336] The method of laminating the adhesive layer of the present invention onto the first surface of the substrate of the present invention is not particularly limited and can be performed, for example, by applying the adhesive composition onto a separator and drying and curing the obtained adhesive composition layer, or by applying the adhesive composition onto a separator and curing the obtained adhesive composition layer by irradiating it with an active energy beam, thereby forming a sheet-like adhesive layer on the separator and bonding the adhesive layer onto the first surface of the substrate of the present invention. Additionally, if necessary, heat drying may also be performed.

[0337] When performing curing by irradiation with active energy rays, it is preferable to also install a separator on the surface of the coating film and irradiate the active energy rays while supporting the adhesive composition by sandwiching it between two separators, thereby preventing inhibition of polymerization by oxygen.

[0338] Another method of laminating the adhesive layer of the present invention onto the first surface of the substrate of the present invention may be, for example, by applying (coating) the adhesive composition onto the first surface of the substrate of the present invention and drying and curing the obtained adhesive composition layer, or by applying (coating) the adhesive composition onto the first surface of the substrate of the present invention and curing the obtained adhesive composition layer by irradiating it with an active energy beam. Additionally, if necessary, further heating and drying may be performed.

[0339] When performing curing by irradiation with active energy rays, it is preferable to install a separator on the surface of the coating film and irradiate the active energy rays while supporting the adhesive composition sandwiched between the substrate of the present invention and the separator, thereby preventing inhibition of polymerization by oxygen.

[0340] Prior to active energy irradiation, the sheet-like coating may be heated for purposes such as removing the solvent. When removing the solvent by heating, it is preferable to perform this before installing the separator.

[0341] Examples of the above active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, or ultraviolet rays, and ultraviolet rays are particularly preferred. In addition, the irradiation energy, irradiation time, and irradiation method of the active energy rays are not particularly limited.

[0342] The above adhesive composition can be prepared by known or conventional methods. For example, a solvent-type acrylic adhesive composition can be prepared by mixing an additive (e.g., a UV absorber, etc.) as needed into a solution containing the above acrylic polymer. For example, an active energy beam-curing acrylic adhesive composition can be prepared by mixing an additive (e.g., a UV absorber, etc.) as needed into a mixture of the above acrylic monomers or a partial polymer thereof.

[0343] In addition, known coating methods may be used for applying (coating) the above adhesive composition. For example, a coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, direct coater, etc. may be used.

[0344] In particular, when forming an adhesive layer using an active energy beam curable adhesive composition, it is preferable that the active energy beam curable adhesive composition includes a photopolymerization initiator. Furthermore, if the active energy beam curable adhesive composition contains an ultraviolet (UV) absorber, it is preferable to include at least a photopolymerization initiator having absorption characteristics over a wide wavelength range as the photopolymerization initiator. For example, it is preferable to include at least a photopolymerization initiator having absorption characteristics in visible light in addition to UV light. This is because, since there is a concern that curing by the active energy beam may be inhibited by the action of the UV absorber, including a photopolymerization initiator having absorption characteristics over a wide wavelength range makes it easier to obtain high photocurability in the adhesive composition.

[0345] Anti-Damage Layer

[0346] In the optical adhesive tape of the present invention, an antistatic layer may be provided on the surface or between any layers. By having an antistatic layer, the optical adhesive tape of the present invention can prevent damage to a substrate, such as an image display panel. It is preferable that the antistatic layer be formed between the substrate of the present invention and the adhesive layer of the present invention.

[0347] The above antistatic layer is not particularly limited, but is, for example, an antistatic layer formed by coating a conductive coating solution containing a conductive polymer onto a separator. Specifically, for example, it is an antistatic layer formed by coating a conductive coating solution containing a conductive polymer onto a first surface of the substrate of the present invention. Specific coating methods include roll coating, bar coating, gravure coating, etc.

[0348] Examples of the above conductive polymers include, for instance, a conductive polymer in which a poly anion is doped into a π-conjugated conductive polymer. Examples of π-conjugated conductive polymers include chain conductive polymers such as polythiophene, polypyrrole, polyaniline, and polyacetylene. Examples of poly anions include polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyethyl acrylate sulfonic acid, and polymethacrylic carboxylic acid.

[0349] 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 be a single layer or two or more layers.

[0350] Separator

[0351] In the optical adhesive tape 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 separator until use. The separator is used as a protective material for the adhesive layer and is peeled off when the optical adhesive tape of the present invention is attached to a substrate.

[0352] As the above separator, conventional release paper, etc., may be used. Specifically, in addition to a substrate having a release treatment layer formed by a release treatment agent on at least one surface, for example, a low-adhesion substrate comprising a fluorine-based polymer (e.g., polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.) or a low-adhesion substrate comprising a non-polar polymer (e.g., olefin-based resin such as polyethylene or polypropylene, etc.) may be used.

[0353] As the above separator, for example, a separator having a release treatment layer formed on at least one side of a separator substrate can be suitably used. Examples of such separator substrates include plastic substrate films (synthetic resin films) such as polyester films (polyethylene terephthalate films, etc.), olefin resin films (polyethylene films, polypropylene films, etc.), polyvinyl chloride films, polyimide films, polyamide films (nylon films), and rayon films, as well as papers (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top-coated paper, etc.), and those formed by laminating or co-extrusion of these (composites of 2 to 3 layers).

[0354] As for the peeling agent constituting the above peeling treatment layer, although not particularly limited, examples include silicone-based peeling agents, fluorine-based peeling agents, long-chain alkyl-based peeling agents, etc. The peeling agent may be used alone or in combination of two or more types.

[0355] The thickness of the above separator is not particularly limited and can be appropriately selected within the range of 5 to 100 μm.

[0356] In order to prevent damage to a substrate such as an image display panel, the above separator may have an antistatic layer formed on at least one side of the separator substrate. The antistatic layer may be formed on one side of the separator (a peel-treated side or an untreated side) or on both sides of the separator (a peel-treated side and an untreated side).

[0357] The above antistatic layer is not particularly limited, but is, for example, an antistatic layer formed by coating a conductive coating solution containing a conductive polymer onto a separator. Specifically, for example, it is an antistatic layer formed by coating a conductive coating solution containing a conductive polymer onto a separator (a peeled surface and / or an untreated surface). Specific coating methods include roll coating, bar coating, gravure coating, etc.

[0358] As the conductive polymer mentioned above, the same type of conductive polymer as the antistatic layer constituting the optical adhesive tape of the present invention may be used.

[0359] 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 be a single layer or two or more layers.

[0360] Surface protection film

[0361] In the optical adhesive tape of the present invention, the second surface of the substrate of the present invention may be protected by a surface protection film. The surface protection film is used as a protective material for the second surface of the substrate of the present invention during manufacturing or transport of the optical adhesive tape of the present invention, the image display device of the present invention, or the tiling display of the present invention.

[0362] Examples of materials for forming the above surface protection 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 a polyethylene terephthalate resin).

[0363] The thickness of the surface protection film is typically 20㎛ to 250㎛, and preferably 30㎛ to 150㎛.

[0364] The above surface protection film is peelably bonded to a second surface of the substrate of the present invention through any suitable adhesive. Preferably, a surface protection film having an adhesive layer is formed, and this is bonded to the second surface of the substrate of the optical adhesive tape of the present invention. As an adhesive used for laminating the above surface protection film, for example, an adhesive composition may be used in which an acrylic resin, a styrene resin, a silicone resin, etc., is used as a base resin, and a crosslinking agent selected from isocyanate compounds, epoxy compounds, aziridine compounds, etc., and further a silane coupling agent, etc., are blended into the base resin. The thickness of the adhesive layer is typically 1 μm to 60 μm, preferably 3 μm to 30 μm. If the adhesive layer is too thin, there is a risk of problems such as reduced adhesiveness or easy incorporation of air bubbles, and if it is too thick, there is a risk of problems such as the adhesive oozing out. An acrylic adhesive is preferably used from the perspective of chemical resistance, adhesion, etc.

[0365] Image display device

[0366] The image display device of the present invention has a laminated structure in which an optical adhesive tape of the present invention and an image display panel are laminated. In FIG. 3, the image display device (20) has an image display panel (4) laminated on an adhesive layer (1) of an optical adhesive tape (10B).

[0367] Since the image display device of the present invention incorporates the optical adhesive tape of the present invention within a laminated structure, it can suppress shrinkage or expansion under usage conditions and maintain transparency without change. Furthermore, the adhesive layer of the present invention sufficiently follows the shrinkage or expansion of the image display device, making it difficult for lifting or peeling to occur. Additionally, if there is an uneven surface step caused by wiring or the like in the image display panel, the adhesive layer of the present invention sufficiently follows the step and can fill it without leaving air bubbles.

[0368] The above image display panel is not particularly limited, but examples include liquid crystal image display panels, self-emissive image display panels (e.g., organic EL (electroluminescence) image display panels, LED image display panels), etc.

[0369] The above image display panel is formed by alternately arranging RGB elements, and in order to improve contrast, it is preferable that the spaces between the RGB elements be filled with a black matrix (BM).

[0370] The image display device of the present invention may have an optical member other than the optical adhesive tape of the present invention and the image display panel on a surface or between any layers. The optical member may include, but is not particularly limited, a polarizing plate, a phase difference plate, an anti-reflective film, a viewing angle adjustment film, an optical compensation film, etc. Furthermore, the optical member may also include a member (such as a decorative film, a decorative film, or a surface protection plate) that performs a role of decoration or protection while maintaining the visibility of the image display device or input device.

[0371] The image display device of the present invention can be manufactured by bonding the image display panel and the adhesive layer of the optical adhesive tape of the present invention.

[0372] Specifically, the attachment of the image display panel and the optical adhesive tape of the present invention can be carried out by laminating under heating and / or pressure. After laminating under heating and / or pressure, curing may be performed by irradiating 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.

[0373] Tiling Display

[0374] The tiling display of the present invention is formed by arranging a plurality of image display devices of the present invention. In FIG. 4, the tiling display (30) is formed by arranging nine image display devices (20) (the stacked structure is omitted from illustration) in a 3×3 arrangement on a support substrate (31) in a tile-like manner, and the image display devices (20) are in contact with each other at a gap (32). As the support substrate, a glass plate or a plastic film similar to the substrate of the present invention may be used.

[0375] Since the image display device of the present invention suppresses shrinkage or expansion under usage conditions, it is difficult for gaps or overlaps to occur between multiple image display devices in the tiling display of the present invention, gaps are not easily noticeable, and a good appearance is maintained. In addition, shrinkage or expansion is minimal, and transparency can be maintained without change. Furthermore, the adhesive layer of the present invention sufficiently follows the shrinkage or expansion of the image display device, and problems caused by lifting or peeling can also be prevented.

[0376] In addition, in the tiling display of the present invention, if an anti-reflection treatment and / or an anti-glare treatment is applied to the second surface of the substrate of the present invention, it is preferable in that it can prevent reflection caused by metal wiring or ITO wiring, etc., disposed on the substrate of the image display device of the present invention. In addition, in the tiling display, it is also preferable in that the gap between the image display devices of the present invention becomes difficult to see.

[0377] The tiling display of the present invention may comprise a member other than the image display device and the support substrate of the present invention. Such a member may include, but is not particularly limited, a backlight, a touch sensor, etc.

[0378] The tiling display of the present invention can be manufactured by arranging a plurality of image display devices of the present invention on the support substrate without gaps and fixing them by sealing the outermost surface with glass, etc.

[0379] Examples

[0380] The present invention will be described in more detail below based on examples, but the present invention is not limited by these examples.

[0381] Preparation Example 1

[0382] (Preparation of Banghyeonseong Film 1)

[0383] [Preparation of Coating Solution for Forming Antifungal Layer 1]

[0384] As a resin included in the anti-glare layer forming material, 40 parts by weight of UV-curable urethane acrylate resin (manufactured by Shin-Nakamura Chemical, trade name "NK Oligo UA-53H-80BK"), 57.5 parts by weight of polyfunctional acrylate with pentaerythritol triacrylate as the main component (manufactured by Osaka Yuki Chemical Co., Ltd., trade name "Viscot #300"), 2.5 parts by weight of a diluted solution of a composition for an optical adjustment layer containing zirconia particles and a UV-curable resin ("Opster Z7540", manufactured by JSR), 2.8 parts by weight of silicon particles (manufactured by Momentive Performance Materials Japan Kodo Co., Ltd., trade name "Tospearl 130ND"), and as a thixotropy-imparting agent, synthetic smectite which is an organic clay (manufactured by Kunimine Chemical Co., Ltd., trade name "Smecton SAN") 2.5 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD 907"), 3 parts by weight of a cross-linked acrylic styrene copolymer fine particle (manufactured by Sekisui Kasei Kogyo, trade name "SSX-103DXE"), and 0.1 parts by weight of a leveling agent (manufactured by Kyoesha Chemical Co., Ltd., trade name "LE-303") were mixed. In addition, the above organic clay was used after diluting it with toluene so that the solid content was 6% by weight. This mixture was diluted with a toluene / cyclopentanone (CPN) mixed solvent (weight ratio 64 / 36) so that the solid content concentration was 38% by weight, and an anti-glare layer forming material (coating liquid) was prepared using an ultrasonic disperser.

[0385] [Formation of Antifungal Layer 1]

[0386] As a substrate, a transparent plastic film substrate (PET film, manufactured by Toray Corporation, trade name "38U413", thickness: 38 μm) was prepared. On one side of the transparent plastic film substrate, the anti-glare layer forming material (coating liquid) was applied using a wire bar to form a coating film (coating process). Subsequently, the coating film was dried by heating at 95°C for 1 minute (drying process). Afterward, ultraviolet light with an integrated light intensity of 300 mJ / cm² was irradiated using a high-pressure mercury lamp, and the coating film was cured to form an anti-glare layer with a thickness of 6.5 μm. In this way, a laminate of the light-transmitting substrate and the anti-glare layer 1 was obtained.

[0387] [Preparation of coating solution for forming anti-reflection layer 1]

[0388] 100 parts by weight of a polyfunctional acrylate with pentaerythritol triacrylate as the main component (manufactured by Osaka Yuki Chemical Co., Ltd., trade name "Viscot #300"), 100 parts by weight of hollow nanosilica particles (manufactured by Nikki Shokubai Kasei Chemical Co., Ltd., trade name "Srulia 5320"), 40 parts by weight of solid nanosilica particles (manufactured by Nissan Chemical Co., Ltd., trade name "MIBK-ST", solid content 30 wt%, weight average particle size 10 nm), 12 parts by weight of a fluorine element-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203"), 5 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), and a photopolymerization initiator (manufactured by BASF, trade name 5 parts by weight of “OMNIRAD2959” were mixed. To the mixture, a mixed solvent comprising MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) mixed in a weight ratio of 70:30 was added as a diluent solvent to make the total solid content 1.5% by weight, and the mixture was stirred to prepare a coating solution for forming an anti-reflective layer.

[0389] [Formation of Anti-reflection Layer 1]

[0390] The coating solution for forming the anti-reflection layer was applied directly to the surface of the anti-reflection layer of the laminate of the light-transmitting substrate and the anti-reflection layer 1 using a wire (coating process). The coated solution was heated at 80°C for 1 minute and dried to form a coating film (drying process). After drying, the coating film was cured by irradiating it with ultraviolet light having an integrated light intensity of 300 mJ / ㎠ using a high-pressure mercury lamp (curing process). By doing so, the coating film was cured to form an anti-reflection layer 1 with a thickness of 0.1 μm (anti-reflection layer formation process). In this manner, the anti-reflection film 1 of the present Manufacturing Example 1 was manufactured.

[0391] Preparation Example 2

[0392] (Preparation of Banghyeonseong Film 2)

[0393] [Formation of Antifungal Layer 2]

[0394] In preparing the coating solution for forming the anti-glare layer, the amount of polyfunctional acrylate with pentaerythritol triacrylate as the main component was changed to 60 parts by weight, the amount of silicon particles was changed to 0.9 parts by weight, synthetic smectite which is an organic clay was changed as a thixotropy-imparting agent to 1.5 parts by weight, and a diluted solution of a composition for an optical adjustment layer containing zirconia particles and a UV-curable resin, and fine particles of cross-linked acrylic styrene copolymer resin were not used, except that a laminate of the light-transmitting substrate and the anti-glare layer 2 was prepared in the same manner as in Preparation Example 1.

[0395] [Formation of Anti-reflection Layer 2]

[0396] In preparing the coating solution for forming the anti-reflection layer, the anti-reflection layer 2 was formed in the same manner as in Preparation Example 1, except that the amount of hollow nanosilica particles was changed to 240 parts by weight. In this way, the anti-reflection film 2 of Preparation Example 2 was prepared.

[0397] Preparation Example 3

[0398] (Preparation of Banghyeonseong Film 3)

[0399] Except for using a transparent plastic film substrate (COP film, manufactured by Nippon Zeon Co., Ltd., product name "ZF14", thickness: 50 μm) as the substrate for forming the anti-glare layer, the anti-glare film 3 of this Preparation Example 3 was prepared in the same manner as Preparation Example 1.

[0400] Preparation Example 4

[0401] (Preparation of Banghyeonseong Film 4)

[0402] Except for using a transparent plastic film substrate (PEN film, manufactured by Toyobo Co., Ltd., product name "Q51", thickness: 25 μm) as the substrate for forming the anti-glare layer, the anti-glare film 4 of the present Preparation Example 4 was prepared in the same manner as Preparation Example 1.

[0403] Preparation Example 5

[0404] (Preparation of Banghyeonseong Film 5)

[0405] Except for using a transparent plastic film substrate (PEEK film, manufactured by Kurabo Co., Ltd., product name "EXPEEK", thickness: 50 μm) as the substrate for forming the anti-glare layer, the anti-glare film 5 of the present Preparation Example 5 was prepared in the same manner as Preparation Example 1.

[0406] Preparation Example 6

[0407] (Manufacture of transparent plastic film substrate)

[0408] For every 81.98 parts by mass of isosorbide (hereinafter abbreviated as “ISB”), 47.19 parts by mass of tricyclodecanedimethanol (hereinafter abbreviated as “TCDDM”), 175.1 parts by mass of diphenyl carbonate (hereinafter abbreviated as “DPC”), and 0.979 parts by mass of a 0.2% by mass aqueous solution of cesium carbonate as a catalyst were introduced into a reaction vessel, and under a nitrogen atmosphere, as the first step of the reaction, the heating vessel temperature was heated to 150°C and the raw materials were dissolved while stirring as necessary (about 15 minutes). Subsequently, the pressure was increased from atmospheric pressure to 13.3 kPa, and the heating vessel temperature was raised to 190°C for 1 hour, while the generated phenol was discharged out of the reaction vessel. After maintaining the entire reaction vessel at 190°C for 15 minutes, as a second step, the pressure inside the reaction vessel was set to 6.67 kPa, and the heating vessel temperature was raised to 230°C over 15 minutes to discharge the generated phenol out of the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and to remove the generated phenol, the pressure inside the reaction vessel was reduced to 0.200 kPa or less. After reaching a predetermined stirring torque, the reaction was terminated, and the resulting reaction product was extruded into water to obtain polycarbonate resin pellets. After vacuum drying the obtained polycarbonate resin at 80°C for 5 hours, a transparent plastic film substrate composed of polycarbonate resin with a thickness of 40 μm was produced using a film making device equipped with a single-screw extruder (manufactured by Shibaura Kikai Co., Ltd., cylinder set temperature: 250°C), a T-die (width 300 mm, set temperature: 250°C), a cooling roll (set temperature: 120 to 130°C), and a winder.

[0409] (Preparation of Banghyeonseong Film 6)

[0410] In forming the anti-glare layer, the anti-glare film 6 of the present Preparation Example 6 was prepared in the same manner as Preparation Example 1, except that a transparent plastic film substrate composed of the polycarbonate resin obtained above was used as the substrate.

[0411] Preparation Example 7

[0412] (Preparation of Banghyeonseong Film 7)

[0413] Except for using a transparent plastic film substrate (CPI film, manufactured by KOLON, product name "C_50_D", thickness: 50㎛) as the substrate for forming the anti-glare layer, the anti-glare film 7 of the present Preparation Example 7 was prepared in the same manner as Preparation Example 1.

[0414] Preparation Example 8

[0415] (Preparation of Banghyeonseong Film 8)

[0416] Except for using a transparent plastic film substrate (TAC film, manufactured by Fuji Film Co., Ltd., product name "TD80UL", thickness: 80㎛) as the substrate for forming the anti-glare layer, the anti-glare film 8 of the present Preparation Example 8 was prepared in the same manner as Preparation Example 1.

[0417] Preparation Example 9

[0418] (Preparation of acrylic adhesive composition 1)

[0419] [Preparation of Acrylic Oligomers]

[0420] 60 parts by weight of dicyclofentanyl methacrylate (DCPMA) and 40 parts by weight of methyl methacrylate (MMA) as monomer components, 3.5 parts by weight of α-thioglycerol as a chain transfer agent, and 100 parts by weight of toluene as a polymerization solvent were mixed and stirred at 70°C for 1 hour under a nitrogen atmosphere. Subsequently, 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) were added as a thermal polymerization initiator, and the mixture was reacted at 70°C for 2 hours, then the temperature was raised to 80°C and the mixture was reacted for 2 hours. Afterward, the reaction mixture was heated to 130°C to dry and remove toluene, the chain transfer agent, and unreacted monomers, thereby obtaining a solid acrylic oligomer (acrylic oligomer A). The weight average molecular weight of acrylic oligomer A was 5100, and the glass transition temperature (Tg) was 130°C.

[0421] [Preparation of Prepolymer and Acrylic Adhesive Composition 1]

[0422] As monomer components for forming a prepolymer, 60 parts by weight of lauryl acrylate (LA), 22 parts by weight of 2-ethylhexyl acrylate (2EHA), 8 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 10 parts by weight of N-vinyl-2-pyrrolidone (NVP) were combined, and as photopolymerization initiators, 0.1 parts by weight of BASF's "Omnirad 184" and 0.1 parts by weight of BASF's "Omnirad 651" were combined, and polymerization was carried out by irradiating with ultraviolet light to obtain a prepolymer composition. To 100 parts by weight of the above prepolymer composition, 37 parts by weight of 2-ethylhexyl acrylate (2EHA), 0.08 parts by weight of 1,6-hexanediol diacrylate (product name "A-HD-N", manufactured by Shin-Nakamura Chemical Co., Ltd.), 6 parts by weight of the above acrylic oligomer A, and 0.3 parts by weight of a silane coupling agent (Shin-Etsu Chemical "KBM403") were added as post-added components, and then the above were uniformly mixed to prepare an acrylic adhesive composition 1.

[0423] Preparation Example 10

[0424] (Preparation of prepolymer and acrylic adhesive composition 2)

[0425] As monomer components for forming a prepolymer, 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (Osaka Yuki Kagaku Kogyo Co., Ltd. “Viscot #155”) and 19 parts by weight of 4-hydroxybutyl acrylate (4HBA), and as photopolymerization initiators, 0.09 parts by weight of BASF “Omnirad 184” and 0.09 parts by weight of BASF “Omnirad 651” were mixed, and polymerization was carried out by irradiating with ultraviolet light to obtain a prepolymer composition. To 100 parts by weight of the above prepolymer composition, 9 parts by weight of hydroxylethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (DPHA), 0.3 parts by weight of a photopolymerization initiator (BASF’s “Omnirad 651”), and 0.35 parts by weight of a silane coupling agent (Shin-Etsu Chemical’s “KBM403”) were added as post-added components, and then the components were uniformly mixed to prepare an acrylic adhesive composition 2.

[0426] Preparation Example 11

[0427] (Preparation of prepolymer and acrylic adhesive composition 3)

[0428] As monomer components for forming a prepolymer, 78 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of hydroxylethyl acrylate (HEA), and 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and as photopolymerization initiators, 0.035 parts by weight of BASF's "Omnirad 184" and 0.035 parts by weight of BASF's "Omnirad 651" were combined, and polymerization was carried out by irradiating with ultraviolet light to obtain a prepolymer composition. To 100 parts by weight of the above prepolymer composition, 17.6 parts by weight of hydroxylethyl acrylate (HEA), 0.294 parts by weight of 1,6-hexanediol diacrylate (product name "A-HD-N", manufactured by Shin-Nakamura Chemical Co., Ltd.), 11.8 parts by weight of the above acrylic oligomer A, and 0.35 parts by weight of a silane coupling agent (Shin-Etsu Chemical "KBM403") were added as post-added components, and then the above were uniformly mixed to prepare an acrylic adhesive composition 3.

[0429] Example 1

[0430] (Preparation of inorganic adhesive layer 1)

[0431] A polyethylene terephthalate (PET) film with a thickness of 75 μm ("Diafoil MRF75" manufactured by Mitsubishi Chemical), having a silicone-based release layer on its surface, was used as a substrate (a combined release film). The above-described acrylic adhesive composition 1 was applied to the release layer of the substrate to a thickness of 25 μm to form a coating layer. On this coating layer, a release layer of a PET film with a thickness of 75 μm ("Diafoil MRE75" manufactured by Mitsubishi Chemical), having one side treated with silicone release, was bonded as a cover sheet (a combined release film). Ultraviolet light was irradiated onto this laminate using a black light positioned so that the irradiation intensity on the irradiation surface directly below the lamp from the cover sheet side was 5 mW / cm², thereby performing photocuring to obtain a non-substrate adhesive layer 1 with a thickness of 25 μm.

[0432] (Preparation of adhesive tape 1)

[0433] By peeling off one release film from the non-substrate adhesive layer 1 obtained above to expose the adhesive surface, and attaching it to the non-anti-fouling layer surface of the anti-fouling film 1 shown in Preparation Example 1, an adhesive tape 1 comprising an anti-fouling film 1 / adhesive layer 1 / release film was obtained.

[0434] Example 2

[0435] (Preparation of adhesive tape 2)

[0436] Except for using the anti-fouling film 2 described above, an adhesive tape 2 comprising an anti-fouling film 2 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0437] Example 3

[0438] (Preparation of non-material adhesive layer 2)

[0439] Except for using the acrylic adhesive composition 2 described above, an inorganic adhesive layer 2 with a thickness of 25 μm was obtained in the same manner as in Example 1.

[0440] (Preparation of adhesive tape 3)

[0441] Except for using the non-material adhesive layer 2 obtained above, an adhesive tape 3 comprising a non-fouling film 1 / adhesive layer 2 / release film was obtained in the same manner as in Example 1.

[0442] Example 4

[0443] (Preparation of adhesive tape 4)

[0444] Except for using the anti-fouling film 3 described above, an adhesive tape 4 comprising an anti-fouling film 3 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0445] Example 5

[0446] (Preparation of adhesive tape 5)

[0447] Except for using the anti-fouling film 4 described above, an adhesive tape 5 comprising an anti-fouling film 4 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0448] Example 6

[0449] (Preparation of adhesive tape 6)

[0450] Except for using the anti-fouling film 5 described above, an adhesive tape 6 comprising an anti-fouling film 5 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0451] Example 7

[0452] (Preparation of adhesive tape 7)

[0453] Except for using the anti-fouling film 6 described above, an adhesive tape 7 comprising an anti-fouling film 6 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0454] Example 8

[0455] (Preparation of adhesive tape 8)

[0456] Except for using the anti-fouling film 7 described above, an adhesive tape 8 comprising an anti-fouling film 7 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0457] Comparative Example 1

[0458] (Preparation of adhesive tape 9)

[0459] Except for using the anti-fouling film 8 described above, an adhesive tape 9 comprising an anti-fouling film 8 / adhesive layer 1 / release film was obtained in the same manner as in Example 1.

[0460] Comparative Example 2

[0461] (Preparation of inorganic adhesive layer 3)

[0462] Except for using the acrylic adhesive composition 3 described above, an inorganic adhesive layer 3 with a thickness of 25 μm was obtained in the same manner as in Example 1.

[0463] (Preparation of adhesive tape 10)

[0464] Except for using the anti-fouling film 8 and non-substrate adhesive layer 3 described above, an adhesive tape 10 comprising an anti-fouling film 8 / adhesive layer 3 / release film was obtained in the same manner as in Example 1.

[0465] (evaluation)

[0466] The following evaluation was performed using the adhesive tapes obtained in the above examples and comparative examples. The evaluation method is shown below. The results are shown in Table 2.

[0467] (1) Average change rate of dimensions

[0468] The adhesive tape prepared in each example and each comparative example was cut into an approximate square shape when viewed from a plane of 100 mm in the MD direction × 100 mm in the TD direction, and a cross pattern scratch was created at each of the four corners to produce a test specimen.

[0469] In the test specimen (25°C) before heating, the distance (length) between the MD direction and the distance (length) between the TD direction of the scratch (cross pattern center) was measured at room temperature (25°C) using a CNC 3D measuring machine (Mitutoyo Corporation, “LEGEX774”). By doing so, the lengths before heating were obtained in the MD direction and the TD direction, respectively.

[0470] Next, the test specimen was heated for 500 hours in an environment of 60°C and 90% relative humidity, and then cooled at room temperature (25°C) for 1 hour. Afterward, the distance between the MD direction and the distance between the TD direction of the scratches were measured using a CNC 3D measuring machine. In this way, the length after heating was obtained for each of the MD direction and the TD direction. Subsequently, the dimensional change rates A1 and A2 for each of the MD direction and the TD direction were calculated using the following formula, and the average value was taken as the average dimensional change rate (%). In addition, the ratio of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction (A1 / A2) was calculated.

[0471] Dimensional change rate (%) = [Length after heating (mm) - Length before heating (mm)] / Length before heating (mm) × 100

[0472] Average dimensional change rate (%) = [Dimensional change rate in MD direction + Dimensional change rate in TD direction] / 2

[0473] (2) Maximum amount of curl

[0474] In each example and each comparative example, the release film of the adhesive tape prepared was peeled off, and a PET film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100E50", thickness: 50 μm) was attached, and the resulting laminate was cut into an approximately square shape when viewed from a 100 mm × 100 mm plane to produce a test specimen.

[0475] Next, the test specimen was heated for 500 hours in an environment of 60°C and 90% relative humidity, and then cooled at room temperature (25°C) for 1 hour. After that, the specimen was placed on a horizontal plane with the convex side facing downward, and the distance from the horizontal plane was measured at four points, and the distance from the horizontal plane to the longest point was set as the maximum curl amount (mm).

[0476] In addition, the maximum curl amount measured with the PET film side of the laminate placed on a horizontal plane so that it is the lower side was +, and the maximum curl amount measured with the substrate side (opposite side of the PET film) of the laminate placed on a horizontal plane so that it is the lower side was -.

[0477] (3) Reflectance

[0478] The adhesive surface of the adhesive tape obtained in each example and each comparative example was attached to a black acrylic plate and prepared as a test specimen. The obtained test specimen was placed with the adhesive tape side facing the light source side of a spectrophotometer U4100 (manufactured by Hitachi High Technology Co., Ltd.), and the reflectance (%) in the visible light region of 5° specular reflection was measured.

[0479] (4) Hayes

[0480] The adhesive tapes obtained in each example and each comparative example were measured at room temperature (23℃) using a haze measuring device (Murakami Shikisai Genkyusho HR-100). The measurement was repeated three times, and the average value was taken as the measurement value.

[0481] (5) Shear force of the adhesive layer

[0482] The adhesive tape obtained in each example and comparative example was cut to a size of 10 mm in width and 100 mm in length, and after peeling off the separator, it was bonded to an acrylic resin plate (Acrylite Mitsubishi Chemical) so that the adhesive (adhesive) area of ​​the adhesive layer of the adhesive tape was 1 cm², and then tensile in the shear direction at 23°C with a peeling speed of 0.06 mm / min, and the maximum load (N / cm²) at that time was used as the shear force.

[0483] (6) Storage modulus of the adhesive layer, loss tangent and glass transition temperature of the adhesive layer

[0484] A separator was peeled off from the adhesive layer obtained in each example and comparative example, and a plurality of adhesive layers were laminated to produce a test sample with a thickness of approximately 2 mm. This test sample was punched into a disc with a diameter of 7.9 mm, inserted into a parallel plate, 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' and loss tangent tangent tanδ at each temperature were read. Additionally, the temperature at which tanδ is maximized was defined as the glass transition temperature of the adhesive layer.

[0485] (Measurement conditions)

[0486] Transformation Mode: Twist

[0487] Measurement frequency: 1Hz

[0488] Measurement temperature: -70℃ to 150℃

[0489] (7) 300% tensile residual stress value of the adhesive layer

[0490] The adhesive layer obtained in each example and comparative example was cut to a size of 40 mm × 40 mm, the separator on one side was peeled off, the adhesive surfaces were folded once to bond together, the separator on one side was peeled off again, and the adhesive surfaces were bonded together again to produce an adhesive layer sample with a size of approximately 10 mm × 40 mm and a thickness of approximately 400 μm. The adhesive layer sample was set in a tensile testing machine with a chuck distance of 20 mm, and tensile was performed to 60 mm (300%) at a tensile speed of 200 mm / min (the chuck distance after tensile was 80 mm). The sample was fixed for 300 seconds at the 60 mm tensile position, the stress value was measured thereafter, and the "300% tensile residual stress value" was calculated by the following formula.

[0491] 300% tensile residual stress value (N / cm²) = Stress value after holding fixed for 300 seconds (N) / (4 × Adhesive sheet thickness (mm) / 10)

[0492] (8) Deformation A, deformation B and restoration rate

[0493] A separator was peeled off from the adhesive layer obtained in each example and comparative example, and a plurality of adhesive layers were laminated to produce a test sample with a thickness of about 2 mm. This test sample was punched into a disc shape with a diameter of 7.9 mm and used as a sample. A shear test to determine "deformation amount A," "deformation amount B," and "restoration rate" was performed in the form shown in FIG. 5. Specifically, using the "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific, which has parallel plates (41 and 42) with a diameter of 7.9 mm, the upper surface of the parallel plate (41) and the lower surface of the parallel plate (42) were positioned to come into contact with the lower surface and upper surface of the adhesive layer of the sample, respectively (Fig. 5 (b)). Next, dynamic viscoelasticity measurements were performed under the following measurement conditions, and the amount of deformation A at 500 Pa and 600 seconds (Fig. 5 (c)) and the amount of deformation B at 0 Pa and 1800 seconds (Fig. 5 (d)) were read, and the recovery rate was calculated by the following formula.

[0494] (Measurement conditions)

[0495] Transformation Mode: Twist

[0496] Measurement program: 500 Pa, maintain for 600 seconds, then 0 Pa, maintain for 1800 seconds.

[0497] Measured temperature: 60℃

[0498] Axial Force: 0.2N

[0499] Restoration rate: (Deformation A - Deformation B) / Deformation A × 100

[0500] (9) Humidity expansion rate

[0501] The adhesive tapes obtained in each example and comparative example were cut to a width of 2 mm in the TD direction and a length of 20 mm in the MD direction, and measurements were performed using the Bruker AXS Co., Ltd. HC-TMA4000SA type under the following conditions.

[0502] (Measurement conditions)

[0503] Transformation Mode: Seal

[0504] Load: 2g

[0505] Duration: 5 hours

[0506] Heating rate: 5% RH / min

[0507] Measurement atmosphere: Maintained at 60°C and 30% relative humidity until saturated, and controlled at 60°C and 60% relative humidity.

[0508] (10) Humidity expansion coefficient of the material

[0509] The humidity expansion coefficient was determined by measuring the elongation of each film when the humidity was varied from 30% RH to 60% RH at 60°C using the Bruker AXS HC-TMA4000SA type (unit: / RH%).

[0510] The humidity expansion coefficient (α) was calculated by the following equation.

[0511] α=ΔL / {(T2-T1)×L}

[0512] T1: Humidity (%RH) at the low humidity side for calculating the humidity expansion coefficient

[0513] T2: High humidity (%RH) for calculating the humidity expansion coefficient

[0514] ΔL: Difference in length between T1 and T2 of the test specimen (㎛)

[0515] L: Length of the test specimen at room temperature (60℃) (㎛)

[0516] (11) Glass transition point (Tg) of the substrate

[0517] Approximately 8 mg of sample was collected, placed in an aluminum container, and DSC measurement was performed.

[0518] Device: TA Instruments Q-2000

[0519] Container: Aluminum container

[0520] Temperature Program: -30℃→300℃

[0521] Heating rate: 10℃ / min

[0522] Atmosphere gas: N2 (50 ml / min)

[0523] (12) Check the gap between the adhesive tapes

[0524] Four adhesive tapes obtained in the examples and comparative examples were cut into 5cm × 5cm pieces and attached to the glass without gaps. After heating for 500 hours in an environment of 60°C and 90% relative humidity, the glass was cooled at room temperature (25°C) for 1 hour. Subsequently, the glass was placed on a backlight, and when the backlight light was irradiated, the gaps between the adhesive tapes were visually inspected and evaluated according to the following criteria.

[0525] ○… The gap between the adhesive tapes was not confirmed.

[0526] ×… A gap between the adhesive tapes was confirmed.

[0527] (13) Check for peeling of adhesive

[0528] The ends of the adhesive tapes of the sample heated for 500 hours at 60°C and 90% relative humidity, which was used to verify the gap between the adhesive tapes above, were examined using an optical microscope and evaluated according to the following criteria.

[0529] ○… No peeling was observed on the adhesive tape.

[0530] ×… Peeling was confirmed on the adhesive tape.

[0531]

[0532] Variations of the present invention are described below.

[0533] [Appendix 1] An optical adhesive tape 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,

[0534] The average dimensional change rate in the width direction and machine direction of the above optical adhesive tape when heated for 500 hours in an environment of 60°C and 90% relative humidity is within ±0.15%, and

[0535] An optical adhesive tape characterized by having an adhesive area of ​​1 cm² of the above adhesive layer bonded to a resin plate, wherein the shear force is 20 N / cm² or less when tensile in the shear direction at a tensile speed of 0.06 mm / min at 23°C.

[0536] [Appendix 2] The average dimensional change rate in the width direction and machine direction when the above optical adhesive tape is heated for 500 hours in an environment of 60°C and 90% relative humidity is denoted as C[%], and

[0537] An optical adhesive tape described in Appendix 1 that satisfies the following formula when the maximum curl amount is D [mm] when the laminate, cut into squares of 10 cm after bonding the adhesive layer of the optical adhesive tape to a PET film with a thickness of 50 μm, is heated for 500 hours in an environment of 60°C and 90% relative humidity.

[0538] |C×D|≤3

[0539] · Maximum curl amount: Place the laminated body on a horizontal plane with the convex side of the curl facing downward, and the highest curvature among the four corners is defined as the maximum curl amount D [mm]. Place the laminated body on a horizontal plane with the PET film side facing downward and measure the maximum curl amount, and place the laminated body on a horizontal plane with the substrate side facing downward and measure the maximum curl amount, and mark it as -.

[0540] [Appendix 3] An optical adhesive tape as described in Appendix 1 or 2, having a glass transition point (Tg) of 60°C or higher as described above.

[0541] [Note 4] An optical adhesive tape described in any one of Notes 1 to 3, wherein the glass transition point (Tg) of the adhesive layer is -10°C or lower.

[0542] [Note 5] An optical adhesive tape described in any one of Notes 1 to 4, wherein the humidity expansion rate of the optical adhesive tape is 0.1% or less when humidified from 60°C relative humidity 30% to 60°C relative humidity 60%.

[0543] [Appendix 6] The humidity expansion coefficient of the above-described item is 5×10 -5 Optical adhesive tape described in any one of Appendix 1 to 5, having a value of / %RH or less.

[0544] [Note 7] An optical adhesive tape described in any one of Notes 1 to 6, wherein the second surface of the above description is treated with an anti-reflective coating and / or an anti-glare coating.

[0545] [Note 8] An optical adhesive tape described in any one of Notes 1 to 7, wherein the adhesive layer is an acrylic adhesive layer comprising an acrylic polymer.

[0546] [Appendix 9] An image display device having an optical adhesive tape described in any one of Appendices 1 to 8 and an image display panel laminated therein.

[0547] [Appendix 10] A tiling display having multiple image display devices listed in Appendix 9 arranged in a row. Explanation of the symbols

[0548] 10A, 10B: Optical adhesive tape 1: Entry 1a: First side of the record 1b: Second side of the entry 2: Adhesive layer 3: Anti-reflective treatment and / or anti-glare treatment 20: Image display device 4: Image display panel 30: Tiling display 31: Support substrate 40: Adhesive layer 41, 42: Parallel plates

Claims

Claim 1 An optical adhesive tape 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, wherein the average dimensional change rate in the width direction and machine direction when the optical adhesive tape is heated for 500 hours in an environment of 60°C and 90% relative humidity is within ±0.15%, the shear force when the adhesive area of ​​the adhesive layer is bonded to a resin plate and tensile at a tensile speed of 0.06 mm / min in the shear direction at 23°C is 20 N / cm² or less, and the adhesive layer is bonded to an image display panel to form an image display device, and is characterized by satisfying at least one selected from the group consisting of (i) and (ii) the average dimensional change rate in the width direction and machine direction when the optical adhesive tape is heated for 500 hours in an environment of 60°C and 90% relative humidity is set to C[%], and the optical adhesive When the adhesive layer of the tape is bonded to a PET film with a thickness of 50 μm and the laminate is cut into 10 cm squares, and the laminate is heated for 500 hours in an environment of 60°C and 90% relative humidity, the following equation is satisfied when the maximum curl amount is denoted as D [mm]. |C × D| ≤ 3 · Maximum curl amount: The laminate is placed on a horizontal plane with the convex side of the curl facing downward, and the highest curvature among the four corners is defined as the maximum curl amount D [mm]. The maximum curl amount measured with the PET film side of the laminate facing downward on the horizontal plane is defined as +, and the maximum curl amount measured with the substrate side of the laminate facing downward on the horizontal plane is defined as -. (ii) The loss tangent of the adhesive layer at 70°C and 1 Hz is 0.15 or greater. Claim 2 An optical adhesive tape according to claim 1, wherein the glass transition point (Tg) of the above description is 60°C or higher. Claim 3 An optical adhesive tape according to claim 1 or 2, wherein the glass transition point (Tg) of the adhesive layer is -10℃ or lower. Claim 4 An optical adhesive tape according to claim 1 or 2, wherein the humidity expansion rate of the optical adhesive tape is 0.1% or less when humidified from 30% relative humidity at 60°C to 60% relative humidity at 60°C. Claim 5 In claim 1 or 2, the humidity expansion coefficient of the above description is 5×10 -5 Optical adhesive tape with / %RH or less. Claim 6 An optical adhesive tape according to claim 1 or 2, wherein the second surface of the above description is treated with an anti-reflective and / or anti-glare treatment. Claim 7 An optical adhesive tape according to claim 1 or 2, wherein the adhesive layer is an acrylic adhesive layer comprising an acrylic polymer. Claim 8 An image display device having an optical adhesive tape described in paragraph 1 or 2 and an image display panel bonded thereto. Claim 9 A tiling display having multiple image display devices as described in paragraph 8 arranged in a row. Claim 10 delete

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