JP2022117422A - optical adhesive tape - Google Patents

Abstract

To provide an optical adhesive tape for maintaining good appearance which can make a gap between a plurality of image display devices inconspicuous and maintain transparency even under a use environment in a tiling display in which a plurality of image display devices are aligned in a tile shape.SOLUTION: There is provided an optical adhesive tape 10A having a laminated structure in which an adhesive layer 2 is laminated on a first surface 1a of a substrate 1, the substrate 1 having the first surface 1a and a second surface 1b. A mean dimensional change rate in the width direction and the machine direction, when the optical adhesive tape 10A is heated for 500 hours in an environment with a temperature of 60°C and a relative humidity of 90%, is within ±0.15%. When an adhesion area of 1 cm2 of the adhesive layer 2 is pasted on a resin plate and the adhesive tape is pulled in the shearing direction at a tension rate of 0.06 mm/min at 23°C, the shearing force is 20 N/cm2 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical pressure-sensitive adhesive tape. More specifically, it relates to an optical pressure-sensitive adhesive tape suitable for manufacturing a tiling display in which a plurality of image display devices are arranged in tiles.

Demand for image display devices with larger screens is increasing with the improvement of image quality such as 4K and 8K. In addition, the use of large-screen image display devices for signage such as advertisement displays and bulletin boards in outdoors and public facilities is also progressing. However, when a large-screen image display device is manufactured, there arises a problem that the yield is lowered and the manufacturing cost is increased. In order to manufacture a large-screen image display device at a lower cost, a tiling display in which a plurality of image display devices are arranged in tiles has been studied (for example, Patent Document 1).

JP 2017-161634 A

In a tiling display, it is necessary to narrow the gap (for example, 100 μm or less) in order to make the space between multiple image display devices inconspicuous. In addition, there is a problem that the image display devices are slightly overlapped to make the gap conspicuous, and furthermore, the transparency is lowered and the appearance is deteriorated. In addition, there is also a problem that the pressure-sensitive adhesive layer that bonds the optical members constituting the image display device cannot follow the contraction and expansion of the image display device, causing lifting and peeling at the ends, resulting in a poor appearance.

The present invention was conceived under the circumstances as described above. To provide an optical pressure-sensitive adhesive tape in which gaps between image display devices are inconspicuous, transparency can be maintained, and good appearance can be maintained.

That is, a first aspect of the present invention provides an optical pressure-sensitive adhesive tape having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer is laminated on the first surface of the substrate. .

The optical pressure-sensitive adhesive tape of the first aspect of the present invention has an average dimensional change of within ±0.15% in the width direction and the machine direction 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 a tiling display in which a plurality of image display devices in which the optical pressure-sensitive adhesive tape of the first aspect of the present invention is laminated is arranged. It is suitable in that it suppresses shrinkage or expansion under the environment of use, suppresses conspicuous gaps between image display devices, maintains a good appearance, reduces shrinkage or expansion, and can maintain transparency without change. be. The average dimensional change rate is preferably within ±0.1% in terms of suppressing conspicuous gaps between image display devices, reducing shrinkage or expansion, and maintaining transparency without change. It may be within 0.05%.

In the optical pressure-sensitive adhesive tape according to the first aspect of the present invention, the pressure-sensitive adhesive layer having an adhesive area of 1 cm ² is attached to a resin plate, and shear force is applied when the pressure-sensitive adhesive layer is pulled in the shear direction at a tensile speed of 0.06 mm/min at 23°C. is 20 N/cm ² or less. In this specification, the term "shearing force" means, unless otherwise specified, "a pressure-sensitive adhesive layer having an adhesive area of 1 cm ² is attached to a resin plate and pulled at 23°C in the shear direction at a tensile speed of 0.06 mm/min. It shall indicate the shear force at the time of

The configuration in which the adhesive layer has a shear force of 20 N/cm ² or less is effective for shrinkage or expansion of the image display device laminated with the optical adhesive tape according to the first aspect of the present invention under the operating environment. It is preferable in that it can sufficiently follow up and suppress floating and peeling. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The shear force of the pressure-sensitive adhesive layer is preferably 15 N/cm ² or less, more preferably 13 N/cm ² or less, in terms of suppressing floating or peeling of the optical pressure-sensitive adhesive tape of the first aspect of the present invention and following steps. may

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 C [%],
The following maximum curl amount when the laminate obtained by laminating the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and then cutting it into a 10 cm square was heated for 500 hours in an environment of 60° C. and a relative humidity of 90%. is D [mm], it is preferable to satisfy the following formula.

|C×D|≦3

・Maximum amount of curl: The laminate is placed on a horizontal surface with the convex surface of the curl facing downward, and the maximum amount of curl D [mm] is defined as the highest warpage at the four corners. The maximum curl amount measured by placing the laminate on a horizontal surface with the PET film side facing down was measured by placing the laminate on a horizontal surface with the substrate side facing down. The maximum amount of curl is -.

The absolute value |C×D| of the product of the average dimensional change rate C [%] and the maximum curl amount D [mm] is 3 or less, the optical adhesive tape according to the first aspect of the present invention. In a tiling display in which a plurality of laminated image display devices are arranged, it is difficult to visually recognize a change in the gap between the image display devices, and the image display device can be accurately attached to the film substrate. |C×D| 4 or less, and may be 2.3 or less, or 2.2 or less.

In the optical pressure-sensitive adhesive tape according to the first aspect of the present invention, the glass transition point (Tg) of the substrate is preferably 60° C. or higher. The structure in which the glass transition point of the base material is 60° C. or higher is used in a tiling display in which a plurality of image display devices in which the optical pressure-sensitive adhesive tape of the first aspect of the present invention is laminated is arranged in a use environment. is preferable in that the mechanical properties of the image display device are stabilized. From the viewpoint 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.

In the optical pressure-sensitive adhesive tape according to the first aspect of the present invention, the pressure-sensitive adhesive layer preferably has a glass transition point (Tg) of -10°C or lower. The structure in which the Tg of the pressure-sensitive adhesive layer is −10° C. or less maintains the stress relaxation property of the pressure-sensitive adhesive layer even in a low-temperature environment, and the optical pressure-sensitive adhesive tape of the first aspect of the present invention is laminated. It is preferable in that the pressure-sensitive adhesive layer can sufficiently follow contraction or expansion under the usage environment of the display device, can suppress lifting and peeling, and can sufficiently secure adhesion to the adherend. The glass transition point of the pressure-sensitive adhesive layer is preferably −15° C. or less, and may be −20° C. or less in terms of suppressing lifting and peeling in the image display device and having good adhesion to the adherend. .

When the optical pressure-sensitive adhesive tape of the first aspect of the present invention is humidified from 60° C. relative humidity of 30% to 60° C. relative humidity of 60%, the humidity expansion rate is preferably 0.1% or less. The structure that the humidity expansion coefficient is 0.1% or less is a tiling display in which a plurality of image display devices in which the optical pressure-sensitive adhesive tape of the first aspect of the present invention is laminated is arranged. It is preferable in that expansion due to moisture absorption is suppressed, gaps between image display devices are suppressed from being conspicuous, shrinkage or expansion is small, and transparency can be maintained without change. From the viewpoint of suppressing the expansion due to moisture absorption of the image display device, the shrinkage or expansion is small, and the transparency can be maintained without change, the humidity expansion rate is preferably 0.08% or less, and 0.06% or less. good too.

In the optical pressure-sensitive adhesive tape according to the first aspect of the present invention, it is preferable that the humidity expansion coefficient of the base material is 5×10 ⁻⁵ /%RH or less. The configuration in which the coefficient of humidity expansion of the substrate is 5×10 ⁻⁵ /% RH or less improves the dimensional stability of the substrate against changes in humidity, and the optical pressure-sensitive adhesive tape of the first aspect of the present invention is In a tiling display in which a plurality of stacked image display devices are arranged, the contraction or expansion of the image display device is suppressed under the usage environment, and the conspicuous gap between the image display devices is suppressed to maintain a good appearance. It is suitable in that it is less likely to shrink or expand, and transparency can be maintained without change. From the viewpoint of dimensional stability of the base material, little shrinkage or expansion, and transparency can be maintained without change, the humidity expansion coefficient of the base material is preferably 3×10 ⁻⁵ /% RH or less, and 2×10 ⁻ It may be ⁵ /% RH or less.

In the optical pressure-sensitive adhesive tape of the first aspect of the present invention, it is preferable that the second surface of the substrate is subjected to antireflection treatment and/or antiglare treatment. The configuration in which the second surface of the base material is antireflection-treated and/or anti-glare-treated is preferable in that reflection due to metal wiring, ITO wiring, or the like arranged on the substrate of the image display device can be prevented. Moreover, in a tiling display in which a plurality of image display devices laminated with the optical pressure-sensitive adhesive tape of the first aspect of the present invention are arranged, it is also preferable in that the gaps between the image display devices are less visible.

In the optical pressure-sensitive adhesive tape according to the first aspect of the present invention, the pressure-sensitive adhesive layer is preferably an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. This configuration is suitable for adjusting the properties (in particular, shear force) of the pressure-sensitive adhesive layer.

A second aspect of the present invention provides an image display device in which the optical pressure-sensitive adhesive tape of the first aspect of the present invention and an image display panel are laminated. A third aspect of the present invention provides a tiling display in which a plurality of image display devices according to the second aspect of the present invention are arranged.
Since the image display device according to the second aspect of the present invention has the optical pressure-sensitive adhesive tape according to the first aspect of the present invention in its laminated structure, it can be prevented from shrinking or expanding under the usage environment. Further, even when the image display device of the second aspect of the present invention shrinks or expands to some extent, the pressure-sensitive adhesive layer sufficiently follows the shrinkage or expansion of the image display device, causing lifting or peeling. Hateful. Therefore, in the tiling display of the third aspect of the present invention, which is manufactured by arranging a plurality of image display devices of the second aspect of the present invention, the gaps between the image display devices are less conspicuous under the usage environment. appearance can be maintained. In addition, transparency can be maintained without change.

By using the optical pressure-sensitive adhesive tape of the present invention for manufacturing a tiling display in which a plurality of image display devices are arranged, shrinkage or expansion of the image display device can be suppressed under the operating environment of the image display device. A good appearance can be maintained with less conspicuous gaps between them. In addition, transparency can be maintained without change. Moreover, even when the image display device expands or contracts to some extent, the pressure-sensitive adhesive layer is less likely to lift or peel off, so a high-performance tiling display can be efficiently manufactured.

FIG. 1 is a schematic diagram showing one embodiment of the optical pressure-sensitive adhesive tape of the present invention. (a) is a cross-sectional view, and (b) is a top view. FIG. 2 is a schematic diagram (sectional view) showing another embodiment of the optical pressure-sensitive adhesive tape of the present invention. FIG. 3 is a schematic diagram (cross-sectional view) showing an embodiment of the image display device of the present invention in which the optical pressure-sensitive adhesive tape of FIG. 2 is laminated. FIG. 4 is a schematic diagram (perspective view) showing an embodiment of the tiling display of the present invention. FIG. 5 is a schematic diagram (perspective view) for explaining the shear test.

A first aspect of the present invention provides an optical pressure-sensitive adhesive tape having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer is laminated on the first surface of the substrate.
The optical pressure-sensitive adhesive tape of the first aspect of the present invention may be referred to herein as "the optical pressure-sensitive adhesive tape of the present invention". In the present specification, the base material and the pressure-sensitive adhesive layer constituting the optical pressure-sensitive adhesive tape of the present invention may be referred to as "the base material of the present invention" and "the pressure-sensitive adhesive layer of the present invention", respectively. In addition, the term "adhesive tape" includes the meaning of "adhesive sheet". That is, the optical pressure-sensitive adhesive tape of the present invention may be a pressure-sensitive adhesive sheet having a sheet-like form.

A second aspect of the present invention provides an image display device in which the optical pressure-sensitive adhesive tape of the first aspect of the present invention and an image display panel are laminated. The image display device according to the second aspect of the present invention may be referred to as "the image display device of the present invention" in this specification.
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 herein as "the tiling display of the present invention".

Embodiments of the optical pressure-sensitive adhesive tape of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto and is merely an example.

FIG. 1 is a schematic diagram showing one embodiment of the optical pressure-sensitive adhesive tape of the present invention. (a) is a cross-sectional view, and (b) is a top view.
In FIG. 1(a), an 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 pressure-sensitive adhesive layer 2 is laminated on the first surface 1a of the substrate 1 .
In FIG. 1(b), the width direction (TD) and machine direction (MD) of the optical pressure-sensitive adhesive tape 10A are defined corresponding to the width direction (TD) and machine direction (MD) of the substrate 1. .

In FIG. 2, optical pressure-sensitive adhesive tape 10B has a laminated structure in which substrate 1 and pressure-sensitive adhesive layer 2 are laminated. The substrate 1 has a first surface 1a and a second surface 1b, and the pressure-sensitive adhesive layer 2 is laminated on the first surface 1a of the substrate 1 . The second surface 1b of the substrate 1 is subjected to antireflection treatment and/or antiglare treatment 3. FIG.

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

FIG. 4 is a schematic diagram (perspective view) showing an 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 laminated structure is not shown) in a 3×3 array in a tile shape on a support substrate 31 . They are in contact with each other with a gap 32 between them.
Each configuration will be described below.

<Optical Adhesive Tape>
The “optical” in the optical pressure-sensitive adhesive tape of the present invention means that it is used for optical purposes, and more specifically means that it is used for manufacturing products (optical products) using optical members. do. Examples of optical products include image display devices, input devices such as touch panels, and liquid crystal image display devices, self-luminous image display devices (eg, organic EL (electroluminescence) image display devices, LED image display devices, etc.). ) and the like. In particular, the optical pressure-sensitive adhesive tape of the present invention is suitable for manufacturing a tiling display in which a plurality of image display devices are arranged in tiles.

The form of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited as long as the pressure-sensitive 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 having an adhesive surface only on one side, or a double-sided adhesive tape having an adhesive surface on both sides. When the optical pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape, the optical pressure-sensitive adhesive tape of the present invention may have a form in which both adhesive surfaces are provided by the pressure-sensitive adhesive layer of the present invention. , one pressure-sensitive adhesive surface is provided by the pressure-sensitive adhesive layer of the present invention, and the other pressure-sensitive adhesive surface is provided by a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer of the present invention (other pressure-sensitive adhesive layer). good. When the optical pressure-sensitive adhesive tape of the present invention constitutes the outermost surface of an optical product, a single-sided pressure-sensitive adhesive tape is preferred, and when adherends (optical members) are adhered together, a double-sided pressure-sensitive adhesive tape is preferred.

In addition to the substrate of the present invention and the adhesive layer of the present invention, the optical pressure-sensitive adhesive tape of the present invention includes other layers, such as substrates other than the substrate of the present invention, as long as the effects of the present invention are not impaired. , a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer of the present invention, an intermediate layer, an undercoat layer, an antistatic layer, a separator, a surface protective film, and the like on the surface or between any layers.

The optical pressure-sensitive adhesive tape of the present invention has an average dimensional change rate of within ±0.15% in the width direction and the machine direction when heated for 500 hours in an environment of 60° C. and 90% relative humidity. The dimensional change rate in the width direction and the machine direction is the percentage of the dimensional change after heating for 500 hours in an environment of 60 ° C. and a relative humidity of 90% when the initial dimensions in the width direction and the machine direction are 100% ( %) and is calculated from the following equation.

Dimensional change rate (%) = [(Dimensions after heating for 500 hours in an environment of 60 ° C. relative humidity of 90%) - (initial dimensions)] / (initial dimensions) x 100

As for the dimensional change rate (%), "+" indicates expansion and "-" indicates shrinkage. The average dimensional change rate in the width direction and the machine direction is the average value of the dimensional change rate in the width direction and the dimensional change rate in the machine direction, and is calculated from the following formula.

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

The dimensions of the optical pressure-sensitive adhesive tape of the present invention are not particularly limited, but can generally be determined by measuring the lengths of the ends of the optical pressure-sensitive adhesive tape in the width direction and machine direction.

The configuration in which the average dimensional change rate is within ±0.15% suppresses shrinkage or expansion in the environment in which the image display device of the present invention is used in the tiling display of the present invention, and reduces the gap between the image display devices. It is suitable in that it suppresses the conspicuousness of , maintains a good appearance, reduces shrinkage or expansion, and can maintain transparency without change. The average dimensional change rate is preferably within ±0.1% in terms of suppressing conspicuous gaps between image display devices, reducing shrinkage or expansion, and maintaining transparency without change. It may be within 0.05%.

Specifically, the average dimensional change rate of the optical pressure-sensitive adhesive tape of the present invention can be measured by the method described in Examples below. The average dimensional change rate in the optical pressure-sensitive adhesive tape of the present invention includes the type and thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient and glass transition point of the substrate, and the pressure-sensitive adhesive layer of the present invention. It can be adjusted by adjusting the type of resin, monomer composition, degree of cross-linking, elastic modulus, glass transition point, and the like.

C [%] is the average dimensional change rate in the width direction and the machine direction when the optical pressure-sensitive adhesive tape of the present invention is heated in an environment of 60 ° C. and 90% relative humidity for 500 hours,
The following maximum curl amount when the laminate obtained by laminating the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and then cutting it into a 10 cm square was heated for 500 hours in an environment of 60° C. and a relative humidity of 90%. is D [mm], it is preferable to satisfy the following formula.

|C×D|≦3

・Maximum amount of curl: The laminate is placed on a horizontal surface with the convex surface of the curl facing downward, and the maximum amount of curl D [mm] is defined as the highest warpage at the four corners. The maximum curl amount measured by placing the laminate on a horizontal surface with the PET film side facing down was measured by placing the laminate on a horizontal surface with the substrate side facing down. The maximum amount of curl is -.

The absolute value |C×D| of the product of the average dimensional change rate C [%] and the maximum curl amount D [mm] is 3 or less. In a tiling display in which a plurality of display devices are arranged, the change in the gap between the image display devices is difficult to see, and the image display device can be adhered to the film substrate with high accuracy. |C×D| 4 or less, and may be 2.3 or less, or 2.2 or less.
The lower limit of |C×D| is not particularly limited, and is preferably as low as possible, but may be 0.001 or more.

The absolute value |D| [mm] of the maximum curl amount is not particularly limited. 60 mm or less is preferable, 55 mm or less is more preferable, and 50 mm or less is even more preferable in that the bonding can be performed with high accuracy.
The lower limit of |D| is not particularly limited, and is preferably as low as possible, but may be 0.1 mm or more.

Specifically, |C×D| and |D| in the optical pressure-sensitive adhesive tape of the present invention can be measured by the method described in Examples below. The |C × D| and |D| It can be adjusted by adjusting the type of resin constituting the agent layer, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition point, and the like.

When the pressure-sensitive adhesive tape for optical use of the present invention is humidified from 60° C. relative humidity of 30% to 60° C. relative humidity of 60%, the humidity expansion coefficient is preferably 0.1% or less. The configuration in which the humidity expansion rate is 0.1% or less suppresses expansion due to moisture absorption of the image display device of the present invention in the tiling display of the present invention, and suppresses conspicuous gaps between the image display devices. It is suitable in that there is little point, shrinkage or expansion, and transparency can be maintained without change. From the viewpoint of suppressing expansion due to moisture absorption of the image display device of the present invention, shrinkage or expansion is small, and transparency can be maintained without change, the humidity expansion rate is preferably 0.08% or less, and 0.06% or less. may
The lower limit of the humidity expansion rate is not particularly limited, and the lower the better, but it may be 0.0001% or more.

Specifically, the humidity expansion coefficient of the optical pressure-sensitive adhesive tape of the present invention can be measured by the method described in Examples below. The humidity expansion coefficient in the optical pressure-sensitive adhesive tape of the present invention includes the type and thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient and glass transition point of the substrate, and the resin constituting the pressure-sensitive adhesive layer of the present invention. can be adjusted by adjusting the type, monomer composition, degree of crosslinking, elastic modulus, glass transition point, and the like.

The ratio of the dimensional change rate in the machine direction to the dimensional change rate in the width direction when the optical pressure-sensitive adhesive tape of the present invention is heated in an environment of 60 ° C. and a relative humidity of 90% for 500 hours (dimensional change rate in the machine direction / width direction Although the dimensional change rate) is not particularly limited, it is preferably 0.5 or more and 2.0 or less. When the ratio is within this range, in the tiling display of the present invention, the difference between the dimensional change rates in the width direction and the machine direction under the usage environment of the image display device of the present invention becomes small, and the difference between the image display devices It is preferable in that a good appearance can be maintained by suppressing conspicuous gaps, shrinkage or expansion is small, and transparency can be maintained without change. The ratio is preferably 0.6 or more and 1.8 or less, more preferably 0.7 or more and 1 in terms of suppressing conspicuous gaps between image display devices, reducing contraction or expansion, and maintaining transparency without change. 0.5 or less.

The ratio (machine direction dimensional change rate/width direction dimensional change rate) in the optical pressure-sensitive adhesive tape of the present invention depends on the type and thickness of the resin constituting the substrate of the present invention, the humidity expansion coefficient of the substrate, and the glass. Adjusting the transition point, the manufacturing conditions of the base material (e.g., the temperature and speed of extrusion molding), the type of resin constituting the pressure-sensitive adhesive layer of the present invention, the monomer composition, the degree of crosslinking, the elastic modulus, the glass transition point, and the like. can be adjusted by

The haze of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 5% or more. The optical pressure-sensitive adhesive tape of the present invention has a haze of 5% or more. In the tiling display of the invention, the gap between the image display devices is preferably less visible, and more preferably 6% or more, and may be 7% or more. The upper limit of the haze of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but from the viewpoint of the 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. .

The haze of the optical pressure-sensitive adhesive tape of the present invention can be measured according to JIS K 7136, and specifically by the method described in Examples below. The haze of the optical pressure-sensitive adhesive tape of the present invention is determined by the type and thickness of the resin constituting the base material of the present invention, the type and thickness of the resin constituting the pressure-sensitive adhesive layer of the present invention, antireflection treatment on the surface of the base material, and / Or it can be adjusted by applying an anti-glare treatment or the like.

Although the reflectance of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, it is preferably 5% or less. The structure that the reflectance of the optical pressure-sensitive adhesive tape of the present invention is 5% or less can prevent reflection due to metal wiring, ITO wiring, etc. arranged on the substrate of the image display panel in the image display device of the present invention. In the tiling display of the present invention, the gap between the image display devices is preferably less visible, and more preferably 3% or less, and may be 1.5% or less. The lower limit of the reflectance of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but may be 0.1% or more, or 0.3% or more.

The reflectance of the optical pressure-sensitive adhesive tape of the present invention can be measured according to JIS K7361-1, and specifically by the method described in Examples below. The reflectance of the optical pressure-sensitive adhesive tape of the present invention depends on the type and thickness of the resin constituting the base material of the present invention, the type and thickness of the resin constituting the pressure-sensitive adhesive layer of the present invention, and the antireflection treatment on the surface of the base material. and/or can be adjusted by applying anti-glare treatment.

Although the total light transmittance of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, it is preferably 85% or more. A configuration in which the optical pressure-sensitive adhesive tape of the present invention has a total light transmittance of 85% or more is preferable in terms of obtaining excellent transparency and an excellent appearance in the image display device of the present invention, and more preferably 88% or more. and may be 90% or more. Although the upper limit of the total light transmittance of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, it may be 95% or less.

The total light transmittance of the optical pressure-sensitive adhesive tape of the present invention can be measured according to JIS K7361-1. The total light transmittance of the optical pressure-sensitive adhesive tape of the present invention depends on the type and thickness of the resin that constitutes the base material of the present invention, the type and thickness of the resin that constitutes the pressure-sensitive adhesive layer of the present invention, and the light reflected on the surface of the base material. It can be adjusted by applying anti-glare treatment and/or anti-glare treatment.

The thickness of the optical pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably in the range of 10 to 500 μm, more preferably in the range of 10 to 500 μm, considering dimensional stability, strength, workability such as handleability, and thinness. It is preferably in the range of 20-300 μm, optimally in the range of 30-200 μm.

<Base material>
Materials constituting the substrate of the present invention include glass and plastic films. Examples of the plastic film include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); "Zeonor" (manufactured by Nippon Zeon Co., Ltd.), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), triacetyl cellulose (TAC), polysulfone, polyarylate, polyether ether ketone (PEEK) ), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer and other plastic materials, and polyethylene terephthalate, which has excellent dimensional stability and is resistant to shrinkage (PET), polyester resins such as polyethylene naphthalate (PEN), cyclic olefin polymers (COP), polycarbonate (PC), polyetheretherketone (PEEK), and transparent polyimide (CPI) are preferred. In addition, these plastic materials can be used individually or in combination of 2 or more types. The substrate of the present invention is a portion that is attached to an adherend together with the pressure-sensitive adhesive layer when the optical pressure-sensitive adhesive tape of the present invention is attached to an adherend (image display panel, etc.). The "base material" does not include a release liner that is peeled off when the optical pressure-sensitive adhesive tape of the present invention is used (attached).

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 base material of the present invention are determined in the manufacturing process of the base material. It refers to the machine direction (MD) and the width direction (TD) is the direction perpendicular to the machine direction.

The base material of the present invention is not particularly limited as long as it is an optical member constituting the optical product, and includes various optical films such as cover members, polarizing plates, and retardation plates, and is preferably used as a cover member. When the substrate of the present invention is a cover member, the second surface is, for example, the outermost surface of the optical product.

The glass transition point (Tg) of the base material 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 preferable in the tiling display of the present invention in terms of stabilizing the mechanical properties of the image display device of the present invention under the usage environment. From the viewpoint of the stability of the mechanical properties of the image display device of the present invention, the glass transition point of the substrate may be 63° C. or higher, or 65° C. or higher. The upper limit of the glass transition point of the base material is not particularly limited, but the glass transition point of the base material is preferably 350° C. or lower, 250° C. or lower, 200° C. or lower, in terms of simplifying the molding process of the base material. °C or lower, 140 °C or lower, 130 °C or lower, or 125 °C or lower.

The glass transition point (Tg) of the substrate of the invention can be measured according to JIS K7121. The glass transition point (Tg) of the base material of the present invention can be adjusted by the type of resin constituting the base material of the present invention.

The humidity expansion coefficient of the base material of the present invention is not particularly limited, but is preferably 5×10 ⁻⁵ /% RH or less. The configuration in which the coefficient of humidity expansion of the base material of the present invention is 5×10 ⁻⁵ /% RH or less improves the dimensional stability of the base material of the present invention against changes in humidity, and is used in the tiling display of the present invention. Suppresses shrinkage or expansion of the image display device of the present invention in the environment, suppresses conspicuous gaps between image display devices, maintains a good appearance, shrinks or expands less, and does not change transparency. It is suitable in that it can be maintained. The humidity expansion coefficient of the substrate of the present invention is preferably 3×10 ⁻⁵ /% RH or less from the viewpoint of the dimensional stability of the substrate of the present invention, little shrinkage or expansion, and the ability to maintain transparency without change. It may be 2×10 ⁻⁵ /% RH or less.
The lower limit of the humidity expansion coefficient of the base material of the present invention is not particularly limited, and the lower the better, but it may be 0.001×10 ⁻⁵ /% RH or more.

Specifically, the coefficient of humidity expansion of the base material of the present invention can be measured by the method described in Examples below. The humidity expansion coefficient of the base material of the present invention can be adjusted by the type of resin constituting the base material of the present invention, the conditions (temperature, extrusion speed, etc.) during the production of the base material, and the like.

The haze of the base material of the present invention is not particularly limited, but is preferably 5% or more. The configuration in which the haze of the base material of the present invention is 5% or more can prevent reflection due to metal wiring, ITO wiring, etc. arranged on the substrate of the image display panel in the image display device of the present invention. In the tiling display, the gap between the image display devices is preferably less visible, and more preferably 6% or more, and may be 7% or more. The upper limit of the haze of the base material of the present invention is not particularly limited, but from the viewpoint of the 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.

The haze of the substrate of the present invention can be measured according to JIS K7136. The haze of the substrate of the present invention can be adjusted by the type and thickness of the resin that constitutes the substrate of the present invention, and by subjecting the surface of the substrate to antireflection treatment and/or antiglare treatment.

Although the reflectance of the substrate of the present invention is not particularly limited, it is preferably 5% or less. The configuration in which the reflectance of the base material of the present invention is 5% or less can prevent reflection due to metal wiring, ITO wiring, etc. arranged on the substrate of the image display panel in the image display device of the present invention. In the tiling display of (1), the gap between the image display devices is preferably less visible, 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.

The reflectance of the substrate of the invention can be measured according to JIS K7361-1. The reflectance of the base material of the present invention can be adjusted by the type and thickness of the resin constituting the base material of the present invention, and by subjecting the surface of the base material to antireflection treatment and/or antiglare treatment.

Although the thickness of the substrate of the present invention is not particularly limited, it is preferably in the range of 10 to 500 μm, more preferably in the range of 10 to 500 μm, considering dimensional stability, strength, workability such as handleability, thin layer property, and the like. It ranges from 20 to 300 μm, optimally from 30 to 200 μm. The refractive index of the substrate of the present invention is not particularly limited, but is, for example, in the range of 1.30 to 1.80, preferably in the range of 1.40 to 1.70.

The second surface of the substrate of the present invention is preferably subjected to reflective surface treatment and/or antiglare treatment. The configuration in which the second surface of the substrate of the present invention is subjected to reflective surface treatment and/or anti-glare treatment prevents reflection due to metal wiring, ITO wiring, etc. arranged on the substrate of the image display device of the present invention. It is preferable in that it can be done. Moreover, in the tiling display of the present invention, it is also preferable in that the gaps between the image display devices are less visible.

As the antireflection treatment, any known antireflection treatment can be used without particular limitation, and examples thereof include antireflection (AR) treatment.

As the antireflection (AR) treatment, a known AR treatment can be applied without particular limitation. It can be carried out by forming an antireflection layer (AR layer) in which two or more layers of thin films or optical thin films are laminated. The AR layer exhibits an anti-reflection function by canceling out the reversed phases of the incident light and the reflected light using the interference effect of light. The wavelength region of visible light that exhibits the antireflection function is, for example, 380 to 780 nm, and the wavelength region with particularly high luminosity is in the range of 450 to 650 nm. It is preferable to design the AR layer so that

The AR layer generally includes a multilayer antireflection layer having a structure in which two to five optical thin layers (thin films with strictly controlled thickness and refractive index) are laminated. By forming multiple layers with a thickness of , the degree of freedom in the optical design of the AR layer increases, the anti-reflection effect can be further improved, and the spectral reflection characteristics can be made uniform (flat) in the visible light region. become. Since the optical thin film requires high thickness accuracy, each layer is generally formed by dry methods such as vacuum deposition, sputtering, and CVD.

The AR layer can also be formed using a coating solution for forming an antireflection layer. The antireflection layer-forming coating liquid may contain, for example, a resin, a fluorine element-containing additive, hollow particles, solid particles, a diluent solvent, and the like, and can be produced, for example, by mixing these.

Examples of the resin include thermosetting resins and ionizing radiation-curable resins that are cured by ultraviolet light or light. As the resin, it is possible to use a commercially available thermosetting resin, ultraviolet curable resin, or the like.

As the thermosetting resin or UV-curable 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.), electron beams, or the like can be used. Silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, oligomers or prepolymers such as acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols. can give. These may be used individually by 1 type, and may use 2 or more types together.

For the resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group can be used. As the reactive diluent, for example, reactive diluents described in JP-A-2008-88309 can be used, and examples include monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, polyfunctional methacrylates, and the like. As the reactive diluent, tri- or more functional acrylates and tri- or more functional methacrylates are preferable. 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 glycerol ether diacrylate, isocyanuric acid acrylate, and isocyanuric acid methacrylate. These may be used individually by 1 type, and may use 2 or more types together. The weight average molecular weight of the resin before curing may be, for example, 100 or more, 300 or more, 500 or more, 1,000 or more, or 2,000 or more, 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 tends to be low, but cracking tends to be less likely to occur when bent. On the other hand, when the weight-average molecular weight before curing is low, the intermolecular crosslink density tends to improve and the hardness tends to increase.

The resin preferably contains a polyfunctional acrylate (for example, pentathritol triacrylate).

For example, a curing agent may be added to cure the curable resin. The curing agent is not particularly limited, and for example, a known polymerization initiator (eg, thermal polymerization initiator, photopolymerization initiator, etc.) can be used as appropriate. The amount of the curing agent to be added is not particularly limited. 15 parts by weight or more, 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; It can be.

The fluorine element-containing additive is not particularly limited, but may be, for example, an organic compound or an inorganic compound containing fluorine in the molecule. Examples of the organic compound include, but are not limited to, fluorine-containing antifouling coating agents, fluorine-containing acrylic compounds, fluorine- and silicon-containing acrylic compounds, and the like. Specific examples of the organic compound include "KY-1203" (trade name) manufactured by Shin-Etsu Chemical Co., Ltd., "Megafac" (trade name) manufactured by DIC Corporation, and the like. The inorganic compound is also not particularly limited. The amount of the elemental fluorine-containing additive to be added is not particularly limited. 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, and 20% by weight or less, 15% by weight or less , 10 wt % or less, 5 wt % or less, or 3 wt % or less. Further, for example, the weight of the fluorine element-containing additive with respect to 100 parts by weight of the resin in the antireflection layer-forming coating liquid is, for example, 0.05 wt% or more, 0.1 wt% or more, 0 .15 wt% or more, 0.20 wt% or more, or 0.25 wt% or more, and 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or 3 wt% It may be below.

The hollow particles are not particularly limited, but may be, for example, silica particles, acrylic particles, acrylic-styrene copolymer particles, or the like. Examples of the silica particles include trade names "Sururia 5320" and "Sururia 4320" manufactured by Nikki Shokubai & Chemicals Co., Ltd. The weight average particle diameter of the hollow particles is not particularly limited, but may be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, Alternatively, it may be 110 nm or less. The shape of the hollow particles is not particularly limited, and may be, for example, a substantially spherical shape such as a bead, or an irregular shape such as a powder. They are substantially spherical particles with an aspect ratio of 1.5 or less, most preferably spherical particles. By adding the hollow particles, for example, a low refractive index, good antireflection properties, etc. of the antireflection layer can be achieved. The amount of the hollow particles to be added is not particularly limited. parts by weight or more, or 100 parts by weight or more, and may be 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less. From the viewpoint of lowering the refractive index of the antireflection layer, the amount of the hollow particles added is preferably not too small, and from the viewpoint of ensuring the mechanical properties of the antireflection layer, the amount of the hollow particles added should not be too large. is preferred.

The solid particles are not particularly limited, but may be, for example, silica particles, zirconium oxide particles, titanium-containing particles (eg, titanium oxide particles), and the like. Examples of the silica particles include trade names "MEK-2140Z-AC", "MIBK-ST", and "IPA-ST" manufactured by Nissan Chemical Industries, Ltd. The weight average particle diameter of the solid particles is not particularly limited, but may be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, and 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less. , or 100 nm or less. The shape of the solid particles is not particularly limited, and may be, for example, a substantially spherical bead shape, or an irregular shape such as a powder. , an aspect ratio of 1.5 or less, most preferably spherical particles. By adding the solid particles, for example, the fluorine element-containing additive tends to be unevenly distributed on the surface of the coated antireflection layer-forming coating liquid, and the antireflection layer has excellent scratch resistance, A low refractive index, good antireflection properties, and the like can be realized. The amount of the solid particles to be added is not particularly limited. It may be 150 parts by weight or less, 120 parts by weight or less, 100 parts by weight or less, or 80 parts by weight or less.

The diluent solvent may be, for example, a mixed solvent containing MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate). The mixing ratio in this case is not particularly limited. It may be 200 wt% or more, 400 wt% or less, 350 wt% or less, 300 wt% or less, or 250 wt% or less.

The diluent solvent may be, for example, a mixed solvent containing TBA (tertiary butyl alcohol) in addition to MIBK and PMA. The mixing ratio in this case is not particularly limited. It may be 100% by weight or more, 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. Further, 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. , 200 wt.% or less, 180 wt.% or less, 150 wt.% or less, 130 wt.% or less, or 110 wt.% or less.

The amount of the diluent solvent to be added is not particularly limited, either. 5 wt% or more, 1.0 wt% or more, or 1.5 wt% or more, and 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or 3 wt% % or less. From the viewpoint of ensuring coatability (wetness, leveling), it is preferable that the content of the solid content is not too high. is not too low.

Next, the antireflection layer-forming coating solution is applied onto the second surface of the substrate of the present invention (the coating step). The coating method is not particularly limited, and for example, known coating methods such as fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating can be used as appropriate. can. Although the coating amount of the antireflection layer-forming coating solution is not particularly limited, the thickness of the antireflection layer to be formed is, for example, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, or 1.0 μm. 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.

Next, the coated antireflection layer-forming coating liquid is dried to form a coating film (the coating film forming step). Although the drying temperature is not particularly limited, it may be in the range of 30 to 200°C, for example. 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, 190° C. or lower, 180° C. or lower, 170° C. °C or lower, 160 °C or lower, 150 °C or lower, 140 °C or lower, 135 °C or lower, 130 °C or lower, 120 °C or lower, or 110 °C or lower. The drying time is not particularly limited, but may be, for example, 30 seconds or longer, 40 seconds or longer, 50 seconds or longer, or 60 seconds or longer, and may be 150 seconds or shorter, 130 seconds or shorter, 110 seconds or shorter, or 90 seconds or shorter. may

Furthermore, the coating film may be cured (curing step). The curing can be performed, for example, by heating, light irradiation, or the like. Although the light is not particularly limited, it may be, for example, ultraviolet light. The light source for the light irradiation is also not particularly limited, and may be, for example, a high-pressure mercury lamp. The irradiation amount of the energy beam source in the ultraviolet curing is preferably 50 to 500 mJ/cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm. When the irradiation dose is 50 mJ/cm ² or more, curing proceeds sufficiently and the hardness of the formed antireflection layer tends to increase. Also, if it is 500 mJ/cm ² or less, coloring of the formed antireflection layer can be prevented.

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

Although the anti-glare layer is not particularly limited, for example, it is formed using an anti-glare layer-forming material containing a resin, particles, and a thixotropy-imparting agent. A convex portion is formed on the surface of the . With this configuration, the anti-glare layer has excellent display characteristics that achieve both anti-glare properties and prevention of white blurring, and despite the fact that the anti-glare layer is formed using aggregation of particles, there are no defects in appearance. It is possible to prevent the occurrence of protrusions on the surface of the anti-glare layer and improve the yield of products.

Examples of the resin include thermosetting resins and ionizing radiation-curable resins that are cured by ultraviolet light or light. As the resin, it is possible to use a commercially available thermosetting resin, ultraviolet curable resin, or the like.

As the thermosetting resin or UV-curable 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.), electron beams, or the like can be used. Silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, oligomers or prepolymers such as acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols. can give. These may be used individually by 1 type, and may use 2 or more types together.

For the resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group can also be used. As the reactive diluent, for example, a reactive diluent described in JP-A-2008-88309 can be used, and examples include monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, polyfunctional methacrylates, and the like. As the reactive diluent, tri- or more functional acrylates and tri- or more functional methacrylates are preferable. This is because the hardness of the antiglare layer can be made excellent. Examples of the reactive diluent include butanediol glycerol ether diacrylate, isocyanuric acid acrylate, and isocyanuric acid methacrylate. These may be used individually by 1 type, and may use 2 or more types together.

The resin preferably contains a urethane acrylate resin, more preferably a copolymer of a curable urethane acrylate resin and a polyfunctional acrylate (for example, pentathritol triacrylate).

The main functions of the particles for forming the antiglare layer are to make the surface of the formed antiglare layer uneven to impart antiglare properties and to control the haze value of the antiglare layer. The haze value of the antiglare layer can be designed by controlling the refractive index difference between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited, and examples include 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, Examples include calcium sulfate particles. The organic particles are not particularly limited, and examples include 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. Examples thereof include resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyethylene fluoride resin powder, and the like. One type of these inorganic particles and organic particles may be used alone, or two or more types may be used in combination.

The weight average particle size (D) of the particles is preferably in the range of 2.5 to 10 μm. By setting the weight-average particle diameter of the particles within the above range, for example, the anti-glare property is more excellent and white blurring can be prevented. The weight average particle size of the particles is more preferably in the range of 3-7 μm. The weight-average particle diameter of the particles can be measured, for example, by the Coulter counting method. For example, using a particle size distribution measuring device (trade name: Coulter Multisizer, manufactured by Beckman Coulter, Inc.) using the pore electrical resistance method, the volume of the electrolyte solution corresponding to the volume of the particles when the particles pass through the pores. By measuring the electrical resistance, the number and volume of the particles are measured, and the weight average particle diameter is calculated.

The shape of the particles is not particularly limited, and may be, for example, a substantially spherical bead shape, or an irregular shape such as a powder. They are substantially spherical particles with a ratio of 1.5 or less, most preferably spherical particles.

The proportion of the particles in the antiglare layer is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, still more preferably 1 part by weight, relative to 100 parts by weight of the resin. ~7 parts by weight. By setting it within the above range, for example, it is possible to achieve more excellent anti-glare properties and prevent white blurring.

The antiglare layer may contain a thixotropy-imparting agent. By containing the thixotropy-imparting agent, the aggregation state of the particles can be easily controlled. Examples of the thixotropy-imparting agent for forming the antiglare layer include organic clay, polyolefin oxide, and modified urea.

The organoclay is preferably an organized clay in order to improve affinity with the resin. Examples of organic clays include layered organic clays. The organic clay may be self-prepared, or a commercially available product may be used. Examples of the commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasif ME-100, Somasif MAE, Somasif MTE, Somasif MEE, Somasif MPE (trade names, all of which are manufactured by CO-OP Chemical Co., Ltd.). ) manufactured); Organite, Organite D, Organite T (trade names, all manufactured by Hojun Co., Ltd.); Kunipia F, Kunipia G, Kunipia G4 (trade names, manufactured by Kunimine Industry Co., Ltd.); Thixogel VZ, Kraton HT , Kraton 40 (trade name, both manufactured by Rockwood Additives), and the like.

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

The modified urea is a reaction product of an isocyanate monomer or its adduct and an organic amine. The modified urea may be self-prepared, or a commercially available product may be used. Examples of the commercial product include BYK410 (manufactured by Big Chemie).

The thixotropy-imparting agents may be used singly or in combination of two or more.

It is preferable that the height of the convex portion from the roughness average line of the antiglare layer is less than 0.4 times the thickness of the antiglare layer. More preferably, it is in the range of 0.01 times or more and less than 0.4 times, and still more preferably in the range of 0.01 times or more and less than 0.3 times. Within this range, it is possible to suitably prevent the formation of projections that impair the appearance of the convex portion. Since the antiglare layer has convex portions with such a height, it is possible to make appearance defects less likely to occur. Here, the height from the average line can be measured, for example, by the method described in JP-A-2017-138620.

The proportion of the thixotropy imparting agent in the antiglare layer is preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.2 to 4 parts by weight, with respect to 100 parts by weight of the resin.

Although the thickness (d) of the antiglare layer is not particularly limited, it is preferably in the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer within the above range, for example, the optical pressure-sensitive adhesive tape of the present invention can be prevented from curling, and the problem of reduced productivity such as transportability can be avoided. Further, 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. When the thickness (d) of the anti-glare layer and the weight average particle size (D) of the particles are in the above-described combination, the anti-glare property can be further improved. The thickness (d) of the antiglare layer is more preferably in the range of 3-8 μm.

The relationship between the thickness (d) of the antiglare layer and the weight average particle diameter (D) of the particles is preferably within the range of 0.3≦D/d≦0.9. By having such a relationship, it is possible to obtain an anti-glare layer that is more excellent in anti-glare properties, can prevent white blurring, and has no defects in appearance.

In the optical pressure-sensitive adhesive tape of the present invention, as described above, the anti-glare layer forms projections on the surface of the anti-glare layer due to aggregation of the particles and the thixotropy-imparting agent. In the aggregated portion forming the convex portion, the particles are present in a state in which a plurality of the particles are aggregated in the surface direction of the antiglare layer. As a result, the convex portion has a gentle shape. Since the anti-glare layer has convex portions having such a shape, it is possible to maintain the anti-glare property, prevent white blurring, and make appearance defects less likely to occur.

The surface shape of the antiglare layer can be arbitrarily designed by controlling the aggregation state of particles contained in the antiglare layer forming material. The aggregation state of the particles can be controlled by, for example, the material of the particles (for example, chemically modified state of the particle surface, affinity for solvent or resin, etc.), type of resin (binder) or solvent, combination, and the like. Here, the aggregation state of the particles can be controlled by the thixotropy imparting agent contained in the antiglare layer-forming material. As a result, the particles can be aggregated as described above, and the convex portion can have a smooth shape.

In the optical pressure-sensitive adhesive tape of the present invention, when the substrate of the present invention is formed of a resin or the like, it preferably has a permeation layer at the interface between the substrate of the present invention and the antiglare layer. The permeation layer is formed by permeating the resin component contained in the material for forming the antiglare layer into the substrate of the present invention. The formation of the permeation layer is preferable because the adhesion between the substrate of the present invention and the antiglare layer can be improved. The penetration layer preferably has a thickness in the range of 0.2 to 3 μm, more preferably in the range of 0.5 to 2 μm. For example, when the base material of the present invention is a polyester-based resin and the resin contained in the antiglare layer is an acrylic resin, the permeation layer can be formed. The penetration layer can be confirmed and the thickness can be measured, for example, by observing a cross section of the optical pressure-sensitive adhesive tape of the present invention with a transmission electron microscope (TEM).

Even when applied to the optical pressure-sensitive adhesive tape of the present invention having such a permeation layer, it is possible to easily form a desired smooth uneven surface shape that achieves both anti-glare properties and prevention of white blurring. . It is preferable that the permeation layer is formed thicker in order to improve the adhesion of the base material with poor adhesion to the anti-glare layer.

In the antiglare layer, it is preferable that the number of appearance defects having a maximum diameter of 200 μm or more is 1 or less per 1 m ² of the antiglare layer. More preferably, it does not have the appearance defect.

In the irregular shape of the antiglare layer surface, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5. A range of 0 to 4.0 is more preferred, and a range of 1.6 to 4.0 is particularly preferred. Here, the average tilt angle θa is a value defined by the following formula (1). The average tilt angle θa is, for example, a value measured by the method described in JP-A-2017-138620.
Average tilt angle θa=tan-1Δa (1)

In the above formula (1), Δa is, as shown in the following formula (2), in the reference length L of the roughness curve defined in JIS B 0601 (1994 edition), the distance between the top and the valley of the adjacent peaks It is a value obtained by dividing the total (h1+h2+h3 . The roughness curve is obtained by removing surface waviness components longer than a predetermined wavelength from the cross-sectional curve with a phase difference compensation high-pass filter. Further, the cross-sectional curve is a contour that appears at the cut end when the target plane is cut along a plane perpendicular to the target plane.
Δa=(h1+h2+h3...+hn)/L (2)

When θa is within the above range, the anti-glare property is more excellent and white blurring can be prevented.

In forming the antiglare layer, the prepared antiglare layer forming material (coating solution) preferably exhibits thixotropy, and the Ti value defined below is in the range of 1.3 to 3.5. is preferred, and more preferably in the range of 1.3 to 2.8.
Ti value = β1/β2
Here, β1 is the viscosity measured at a shear rate of 20 (1/s) using HAAKE's Rheostress 6000, and β2 is the viscosity measured using HAAKE's Rheostress 6000 at a shear rate of 200 (1/s). Viscosity measured under conditions.

If the Ti value is less than 1.3, defects in appearance tend to occur, and anti-glare properties and white blur characteristics deteriorate. On the other hand, when the Ti value exceeds 3.5, the particles are less likely to agglomerate and more likely to be in a dispersed state.

The method for producing the anti-glare layer is not particularly limited, and it may be produced by any method. Then, the anti-glare layer-forming material (coating liquid) is applied to the second surface of the substrate of the present invention to form a coating film, and the coating film is cured to form an anti-glare layer. . A transfer method using a mold, a method of imparting an uneven shape by an appropriate method such as sandblasting, embossing roll, or the like can also be used together.

The solvent is not particularly limited, and various solvents can be used, and one type may be used alone, or two or more types may be used in combination. There is an optimum solvent type and solvent ratio depending on the composition of the resin, the types and contents of the particles and the thixotropy-imparting agent, and the like. Examples of solvents include, but are not limited to, alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; methyl acetate, ethyl acetate. , Esters such as butyl acetate; Ethers such as diisopropyl ether and propylene glycol monomethyl ether; Glycols such as ethylene glycol and propylene glycol; Cellosolves such as ethyl cellosolve and butyl cellosolve; Aliphatic hydrocarbons such as hexane, heptane and octane Aromatic hydrocarbons such as benzene, toluene, and xylene.

For example, when a permeation layer is formed using a polyester-based resin as the base material of the present invention, a good solvent for the polyester-based resin can be suitably used. Examples of the solvent include ethyl acetate, methyl ethyl ketone, cyclopentanone and the like.

By appropriately selecting the solvent, the thixotropy of the antiglare layer-forming material (coating liquid) by the thixotropy-imparting agent can be exhibited satisfactorily. For example, when using organoclays, toluene and xylene can be suitably used alone or in combination. They can be used or used in combination. For example, when modified urea is used, butyl acetate and methyl isobutyl ketone can be preferably used alone or in combination.

Various leveling agents can be added to the antiglare layer-forming material. As the leveling agent, for example, a fluorine-based or silicone-based leveling agent can be used for the purpose of preventing coating unevenness (uniformizing the coated surface). If antifouling properties are required on the surface of the antiglare layer, or if an antireflection layer (low refractive index layer) or a layer containing an interlayer filler is formed on the antiglare layer, a leveling agent is added as appropriate. can be selected. For example, the inclusion of the thixotropy-imparting agent makes it possible to express thixotropic properties in the coating liquid, so that unevenness in coating is less likely to occur. Therefore, for example, it has an advantage that the options for the leveling agent can be expanded.

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

Pigments, fillers, dispersants, plasticizers, UV absorbers, surfactants, antifouling agents, antioxidants and the like are added to the antiglare layer-forming material as necessary within a range that does not impair the performance. may These additives may be used singly or in combination of two or more.

Conventionally known photopolymerization initiators, such as those described in JP-A-2008-88309, can be used for the anti-glare layer-forming material.

Examples of the method for applying the anti-glare layer-forming material onto the second surface of the substrate of the present invention include a fountain coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, A coating method such as a bar coating method can be used.

The antiglare layer-forming material is applied to form a coating film on the substrate of the present invention, and the coating film is cured. It is preferable to dry the coating film prior to the curing. The drying may be, for example, natural drying, air drying by blowing air, heat drying, or a combination thereof.

The means for curing the coating film of the anti-glare layer-forming material is not particularly limited, but ultraviolet curing is preferable. The irradiation amount of the energy beam source is preferably 50 to 500 mJ/cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm. When the irradiation dose is 50 mJ/cm ² or more, the curing becomes more sufficient, and the hardness of the formed anti-glare layer becomes more sufficient. Also, if it is 500 mJ/cm ² or less, coloring of the formed antiglare layer can be prevented.

As described above, the antiglare layer can be formed on the second surface of the substrate of the present invention. 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 preferably 2H or higher in terms of pencil hardness, although it is also affected by the thickness of the layer.

The antiglare layer may have a multi-layer structure in which two or more layers are laminated.

The above-mentioned AR layer (low refractive index layer) may be arranged on the antiglare layer. For example, when an optical pressure-sensitive adhesive tape is attached to an image display device, one factor that reduces the visibility of the image is the reflection of light at the interface between the air and the anti-glare layer. The AR layer reduces the surface reflection. The antiglare layer and the antireflection layer may each have a multi-layer structure in which two or more layers are laminated.

In addition, in order to prevent the adhesion of contaminants and improve the ease of removal of adhered contaminants, an anti-contamination layer formed of a fluorine group-containing silane compound, a fluorine group-containing organic compound, or the like is used as the antireflection layer and the anti-reflection layer. / Or lamination on the anti-glare layer is preferred.

At least one of the substrate of the present invention and the antiglare layer is preferably subjected to a surface treatment. By surface-treating the surface of the base material of the present invention, the adhesion to the anti-glare layer is further improved. Moreover, if the surface of the anti-glare layer is treated, the adhesion to the AR layer is further improved.

In order to prevent the substrate of the present invention from curling, the other side of the anti-glare layer may be subjected to a solvent treatment. Further, a transparent resin layer may be formed on the other surface of the antiglare layer in order to prevent curling.

<Adhesive layer>
The pressure-sensitive adhesive layer of the present invention may be a pressure-sensitive adhesive layer that does not have a substrate (base layer), or may be a pressure-sensitive adhesive layer that has a substrate. In this specification, the pressure-sensitive adhesive layer that does not have a base material (base layer) may be referred to as a "base-less pressure-sensitive adhesive layer", and the type of pressure-sensitive adhesive layer that has a base material is referred to as a "base-attached pressure-sensitive adhesive layer". It may be referred to as "agent layer". Examples of the substrate-less pressure-sensitive adhesive layer include, for example, a single-layer pressure-sensitive adhesive layer consisting only of the pressure-sensitive adhesive layer of the present invention; pressure-sensitive adhesive layer), and the like. In addition, as the pressure-sensitive adhesive layer with a substrate, a pressure-sensitive adhesive layer having the pressure-sensitive adhesive layer of the present invention on both sides of a substrate, or a pressure-sensitive adhesive layer of the present invention on one side of a substrate and and a pressure-sensitive adhesive layer having another pressure-sensitive adhesive layer on the surface side thereof. As the "base material (base material layer)" constituting the "adhesive layer with a base material", the same plastic film as the base material of the present invention can be used.

The shear force of the adhesive layer of the present invention (shear force when an adhesive area of 1 cm ² is attached to a resin plate and pulled at 23° C. in the shear direction at a tensile speed of 0.06 mm/min) is 20 N/cm ² or less. . In the configuration in which the pressure-sensitive adhesive layer of the present invention has a shear force of 20 N/cm ² or less, the pressure-sensitive adhesive layer of the present invention sufficiently follows contraction or expansion under the operating environment of the image display device of the present invention, and does not lift. It is preferable in that peeling can be suppressed. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The shear force of the pressure-sensitive adhesive layer of the present invention is preferably 15 N/cm ² or less, and may be 13 N/cm ² or less, in order to prevent the optical pressure-sensitive adhesive tape of the present invention from floating or peeling and to follow steps. . The lower limit of the shear force of the pressure-sensitive adhesive layer of the present invention is not particularly limited. cm ² or more is preferable, and it may be 7 N/cm ² or more.

The shearing force of the pressure-sensitive adhesive layer of the present invention is measured by shearing force measurement in Examples described later. The shear force of the pressure-sensitive adhesive layer of the present invention is determined by the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the type and amount of the functional group , type and amount of cross-linking agent), curing conditions (heating conditions, irradiation conditions), and the like.

The glass transition point (Tg) of the pressure-sensitive adhesive layer of the invention is preferably -10°C or lower. The configuration in which the Tg of the pressure-sensitive adhesive layer of the present invention is −10° C. or less maintains the stress relaxation property of the pressure-sensitive adhesive layer even in a low temperature environment, and the image display device of the present invention is resistant to shrinkage or expansion under the usage environment. It is preferable in that the pressure-sensitive adhesive layer can sufficiently follow, can suppress lifting and peeling, and can sufficiently ensure adhesion to the adherend. In terms of suppressing lifting and peeling in the image display device of the present invention and good adhesion to the adherend, the glass transition point of the pressure-sensitive adhesive layer of the present invention is preferably −15° C. or less, and −20° C. or less. It can be. The lower limit of the Tg of the pressure-sensitive adhesive layer of the present invention is not particularly limited. The temperature is preferably above, and may be -40°C or higher.

The glass transition point (Tg) of the pressure-sensitive adhesive layer of the invention is measured by dynamic viscoelasticity measurement in Examples described later. The glass transition point (Tg) of the pressure-sensitive adhesive layer of the present invention is the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the functional group type and amount of cross-linking agent), curing conditions (heating conditions, irradiation conditions), and the like.

The storage elastic modulus of the pressure-sensitive adhesive layer of the present invention at 70° C. and 1 Hz is not particularly limited, but is preferably 80 kPa or less. The structure that the storage elastic modulus of the pressure-sensitive adhesive layer of the present invention at 70° C. and 1 Hz is 80 kPa or less allows the pressure-sensitive adhesive layer of the present invention to sufficiently follow the contraction or expansion under the operating environment of the image display device of the present invention. It is preferable in that it is possible to suppress lifting and peeling. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. In terms of suppressing lifting and peeling of the optical pressure-sensitive adhesive tape of the present invention and being able to follow steps, the storage elastic modulus of the pressure-sensitive adhesive layer of the present invention at 70° C. and 1 Hz is more preferably 70 kPa or less, 60 kPa or less, or 50 kPa. It may be below. The lower limit of the storage elastic modulus at 70° C. and 1 Hz of the pressure-sensitive adhesive layer of the present invention is not particularly limited. 1 kPa or more is preferable, and 5 kPa or more may be sufficient from a viewpoint of property.

The loss tangent of the pressure-sensitive adhesive layer of the present invention at 70° C. and 1 Hz is not particularly limited, but is preferably 0.15 or more. The pressure-sensitive adhesive layer of the present invention has a loss tangent of 0.15 or more at 70° C. and 1 Hz. It is preferable in that it can follow and suppress floating and peeling. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The loss tangent of the pressure-sensitive adhesive layer of the present invention at 70° C. and 1 Hz is preferably 0.2 or more, preferably 0.25 or more, in terms of suppressing lifting and peeling of the optical pressure-sensitive adhesive tape of the present invention and being able to follow steps. Or it may be 0.3 or more. The upper limit of the loss tangent at 70° C. and 1 Hz of the pressure-sensitive adhesive layer of the present invention is not particularly limited. from the point of view, it is preferably 1 or less, and may be 0.8 or less.

The storage elastic modulus and loss tangent at 70° C. and 1 Hz of the pressure-sensitive adhesive layer of the present invention are measured by dynamic viscoelasticity measurement in Examples described later. The storage elastic modulus and loss tangent at 70° C. and 1 Hz of the pressure-sensitive adhesive layer of the present invention are the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used , monomer composition, type and amount of functional groups, type and amount of cross-linking agent), curing conditions (heating conditions, irradiation conditions), and the like.

Although the 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 10 N/cm ² or less. The configuration in which the 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is 10 N/cm ² or less means that the pressure-sensitive adhesive layer of the present invention sufficiently follows contraction or expansion under the operating environment of the image display device of the present invention. It is preferable in that it is possible to suppress lifting and peeling. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is more preferably 7 N/cm ² or less, more preferably 5 N/cm ² or less, in that the pressure-sensitive adhesive tape for optical use of the present invention can be prevented from lifting or peeling and can follow steps. may be The lower limit of the 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but from the standpoint of workability, such as the problem that the pressure-sensitive adhesive layer protrudes from the end portion during storage of the optical pressure-sensitive adhesive tape of the present invention is less likely to occur. Therefore, it is preferably 1 N/cm ² or more, and may be 1.5 N/cm ² or more.

The 300% tensile residual stress value of the adhesive layer of the present invention is measured by the 300% tensile residual stress value measurement in Examples described later. The 300% tensile residual stress value of the pressure-sensitive adhesive layer of the present invention is the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer composition, the functional group type and amount of cross-linking agent), curing conditions (heating conditions, irradiation conditions), and the like.

The recovery rate required in the following shear test of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 95% or less.
<Shear test>
A disc-shaped pressure-sensitive adhesive layer having a thickness of 2 mm and a diameter of 7.9 mm was subjected to a torsional shearing force of 500 Pa for 600 seconds at 60 ° C. from the top and bottom, and the strain amount A (%), and then held at a shearing force of 0 Pa for 1800 seconds. The amount of strain B (%) at the time is measured, and the recovery rate (%) is calculated from the following formula.
Restoration rate (%) = (distortion amount A - distortion amount B) / distortion amount A x 100

In this specification, when referring to "strain amount A", "strain amount B", and "restoration rate", unless otherwise specified, "strain amount A", "strain amount B", "strain amount B", It shall indicate "recovery rate".

The above "shear test" will be described with reference to the drawings. FIG. 5 is a schematic diagram for explaining the shear test, 40 indicates an adhesive layer, and 41 and 42 indicate parallel plates.
The pressure-sensitive adhesive layer 40 is a disc-shaped pressure-sensitive adhesive layer having a thickness of 2 mm and a diameter of 7.9 mm, and is composed of the pressure-sensitive adhesive layer of the present invention. Parallel plates 41 and 42 each have a diameter of 7.9 mm. , and is made of, for example, stainless steel (FIG. 5(a)). The top surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are brought into contact with the bottom surface and the top surface of the adhesive layer 40, respectively (FIG. 5(b)). Next, the ambient temperature is set to 60° C., and a torsional shearing force F of 500 Pa is applied to the pressure-sensitive adhesive layer 40 for 600 seconds (FIG. 5(c)). Next, the shearing force of the parallel plates 41 and 42 is released and left for 1800 seconds with a shearing force of 0 Pa (FIG. 5(d)). The "distortion amount A" is the amount of change in the twisting direction when the shear force F is applied to the outer periphery (100%) of the adhesive layer 40 at the initial stage (Fig. 5(b)) for 600 seconds (Fig. 5(c)). Percentage (%). The "distortion amount B" is the initial (Fig. 5(b)) with respect to the outer periphery (100%) of the adhesive layer 40 when the shear force F is applied for 600 seconds and then left for 1800 seconds at a shear force of 0 Pa (Fig. 5 ( d)) is the percentage (%) of the amount of change in the torsional direction. The recovery rate (%) is calculated from the following formula.

Restoration rate (%) = (distortion amount A - distortion amount B) / distortion amount A x 100

The composition that the restoration rate of the pressure-sensitive adhesive layer of the present invention is 95% or less is that the pressure-sensitive adhesive layer sufficiently follows contraction or expansion under the operating environment of the image display device of the present invention, and can suppress lifting and peeling. , is preferable in that the transparency can be maintained without change. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The recovery rate of the pressure-sensitive adhesive layer of the present invention is more preferably 94% or less, 93.5, in that the optical pressure-sensitive adhesive tape of the present invention can be prevented from floating and peeling, can maintain transparency without change, and can follow steps. % or less. The lower limit of the recovery rate of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but from the viewpoint of workability, such as the problem that the pressure-sensitive adhesive layer protrudes from the end portion during storage of the optical pressure-sensitive adhesive tape of the present invention, it is difficult to occur. It is preferably 80% or more, or 85% or more.

Although the strain amount A of the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 3% or more. In the configuration in which the strain amount A of the adhesive layer of the present invention is 3% or more, the adhesive layer sufficiently follows contraction or expansion under the usage environment of the image display device of the present invention, and lifting and peeling can be suppressed. point is preferable. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The strain amount A of the pressure-sensitive adhesive layer of the present invention is more preferably 4% or more, and may be 5% or more, in order to prevent the optical pressure-sensitive adhesive tape of the present invention from floating or peeling and to follow steps. The upper limit of the strain amount A of the present invention is not particularly limited, but from the viewpoint of processability such as the problem that the adhesive layer protrudes from the edge during storage of the optical adhesive tape of the present invention, transparency is maintained without change. It is preferably 25% or less, and may be 20% or less or 15% or less.

Although the strain amount B of the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 0.1% or more. In the configuration in which the strain amount B of the adhesive layer of the present invention is 0.1% or more, the adhesive layer sufficiently follows contraction or expansion under the operating environment of the image display device of the present invention, and does not lift or peel off. This is preferable in that it can be suppressed. In addition, when an adherend such as an image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer can sufficiently follow the steps and can be filled without leaving air bubbles. The strain amount B of the pressure-sensitive adhesive layer of the present invention is preferably 0.2% or more, even if it is 0.3% or more, in terms of suppressing floating and peeling of the optical pressure-sensitive adhesive tape of the present invention and being able to follow steps. good. The upper limit of the strain amount B of the present invention is not particularly limited, but from the viewpoint of workability such as the problem that the adhesive layer protrudes from the edge during storage of the optical adhesive tape of the present invention, the transparency is maintained without change. It is preferably 10% or less, and may be 8% or less, or 5% or less.

The amount of strain A, the amount of strain B, and the recovery rate of the pressure-sensitive adhesive layer of the present invention are specifically measured by measuring the amount of strain A, the amount of strain B, and the recovery rate in Examples described later. The strain amount A, the strain amount B, and the recovery rate of the pressure-sensitive adhesive layer of the present invention are the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the present invention (for example, the type and molecular weight of the base polymer, the amount used, the monomer Composition, type and amount of functional groups, type and amount of cross-linking agent), curing conditions (heating conditions, irradiation conditions), etc. can be adjusted.

The adhesive constituting the adhesive layer of the present invention is not particularly limited, but for example, acrylic adhesive, rubber adhesive, vinyl alkyl ether adhesive, silicone adhesive, polyester adhesive, polyamide adhesive Adhesives, urethane-based adhesives, fluorine-based adhesives, epoxy-based adhesives, and the like can be used. Among them, acrylic pressure-sensitive adhesives are preferable as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer from the viewpoints of transparency, adhesiveness, weather resistance, cost, and ease of designing the pressure-sensitive adhesive. In other words, the pressure-sensitive adhesive layer of the present invention is preferably an acrylic pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesives may be used alone or in combination of two or more.

The acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth)acryloyl group in the molecule) as a monomer component constituting the polymer. The acrylic polymer is preferably a polymer containing a (meth)acrylic acid alkyl ester as a monomer component constituting the polymer. In addition, an acrylic polymer can be used individually or in combination of 2 or more types.

The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention may be in any form. For example, the pressure-sensitive adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray-curable type, a heat-melting type (hot-melt type), or the like. Among them, solvent-type and active energy ray-curable pressure-sensitive adhesive compositions are preferable from the viewpoint of productivity and the ease with which a pressure-sensitive adhesive layer having excellent optical properties and appearance can be obtained. In particular, active energy ray-curable pressure-sensitive adhesive compositions are preferable from the viewpoint of facilitating control of the above various properties of the pressure-sensitive adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range.

That is, the pressure-sensitive adhesive layer of the present invention is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed from an active energy ray-curable acrylic pressure-sensitive adhesive composition.

Examples of the active energy rays include ionizing radiation such as α-rays, β-rays, γ-rays, neutron beams and electron beams, and ultraviolet rays, with ultraviolet rays being particularly preferred. That is, the active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet-curable pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition) forming the acrylic pressure-sensitive adhesive layer includes, for example, an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as an essential component, or a single Examples include acrylic pressure-sensitive adhesive compositions containing a mixture of monomers (sometimes referred to as a "monomer mixture") or a partial polymer thereof as an essential component. The former includes, for example, a so-called solvent-type acrylic pressure-sensitive adhesive composition. Also. Examples of the latter include so-called active energy ray-curable acrylic pressure-sensitive adhesive compositions. The "monomer mixture" means a mixture containing monomer components that constitute a polymer. The "partially polymerized product" may also be referred to as a "prepolymer", and means a composition in which one or more of the monomer components in the monomer mixture is partially polymerized. do.

The acrylic polymer is a polymer composed (formed) of an acrylic monomer as an essential monomer component (monomer component). The acrylic polymer is preferably a polymer composed (formed) of a (meth)acrylic acid alkyl ester as an essential monomer component. That is, the acrylic polymer preferably contains a (meth)acrylic acid alkyl ester as a structural unit. As used herein, "(meth)acryl" represents "acryl" and/or "methacryl" (either or both of "acryl" and "methacryl"), and so on. In addition, the said acrylic polymer is comprised by 1 type, or 2 or more types of monomer components.

Preferred examples of the (meth)acrylic acid alkyl ester as an essential monomer component include (meth)acrylic acid alkyl esters having a linear or branched alkyl group. In addition, (meth)acrylic-acid alkylester can be used individually or in combination of 2 or more types.

The (meth)acrylic acid alkyl ester having a linear or branched alkyl group is not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, ( meth)isopropyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, (meth)acrylate isopentyl acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylate ) isononyl acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, (meth)acrylate Pentadecyl acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate (stearyl (meth)acrylate), isostearyl (meth)acrylate, nonadecyl (meth)acrylate, (meth)acrylic Examples thereof include (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 20 carbon atoms such as eicosyl acid. Among them, the (meth)acrylic acid alkyl ester having a linear or branched alkyl group is preferably a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 18 carbon atoms. , and more preferably 2-ethylhexyl acrylate (2EHA), isostearyl acrylate (ISTA), lauryl acrylate (LA), and butyl acrylate (BA). In addition, the (meth)acrylic acid alkyl esters having a linear or branched alkyl group can be used alone or in combination of two or more.

The ratio of the (meth)acrylic acid alkyl ester in the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is 50% by weight or more (for example, 50 to 100% by weight). is preferred, more preferably 53 to 90% by weight, still more preferably 55 to 85% by weight.

In addition to the acrylic polymer, the acrylic pressure-sensitive adhesive composition may contain the (meth)acrylic acid alkyl ester. When the acrylic pressure-sensitive adhesive composition contains a (meth)acrylic acid alkyl ester in addition to the acrylic polymer, the content (blended amount) of the (meth)acrylic acid alkyl ester is 100 parts by weight of the acrylic polymer. On the other hand, it is preferably 10 parts by weight or more (for example, 10 to 100 parts by weight), more preferably 20 to 90 parts by weight, still more preferably 30 to 80 parts by weight.

The acrylic polymer may contain a copolymerizable monomer together with the (meth)acrylic acid alkyl ester as a monomer component constituting the polymer. That is, the acrylic polymer may contain a copolymerizable monomer as a structural unit. In addition, a copolymerizable monomer can be used individually or in combination of 2 or more types.

The copolymerizable monomer is not particularly limited, but the various properties of the pressure-sensitive adhesive layer (especially shear force, glass transition point, etc.) can be easily controlled within a predetermined range, and cloudiness in a high-humidity environment From the viewpoint of suppression and durability improvement, adhesion reliability, compatibility with various additives such as ultraviolet absorbers, and transparency, monomers having a nitrogen atom in the molecule and monomers having a hydroxyl group in the molecule are preferable. . That is, the acrylic polymer preferably contains a monomer having a nitrogen atom in the molecule as a structural unit. Moreover, the acrylic polymer preferably contains a monomer having a hydroxyl group in the molecule as a structural unit.

The monomer having a nitrogen atom in the molecule is a monomer (monomer) having at least one nitrogen atom in the molecule (within one molecule). In this specification, the above-mentioned "monomer having a nitrogen atom in the molecule" may be referred to as "nitrogen atom-containing monomer". Although the nitrogen atom-containing monomer is not particularly limited, cyclic nitrogen-containing monomers, (meth)acrylamides, and the like are preferable. Incidentally, the nitrogen atom-containing monomers can be used alone or in combination of two or more.

The 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 vinyl group and has a cyclic nitrogen structure. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure.

Examples of the cyclic nitrogen-containing monomers include N-vinyl cyclic amides (lactam-based vinyl monomers) and vinyl-based monomers having a nitrogen-containing heterocyclic ring.

（式（１）中、Ｒ¹は２価の有機基を示す） Examples of the N-vinyl cyclic amides include N-vinyl cyclic amides represented by the following formula (1).

(In formula (1), R ¹ represents a divalent organic group)

R ¹ in the above formula (1) is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (e.g., carbon number 3 to 5 alkylene groups, etc.).

Examples of the N-vinyl cyclic amide 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-oxazin-2-one, N-vinyl-3,5-morpholinedione, and the like.

Examples of vinyl monomers having a nitrogen-containing heterocyclic ring include acrylic monomers having a nitrogen-containing heterocyclic ring such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.

The vinyl-based monomer having a nitrogen-containing heterocycle is not particularly limited, but examples include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, and N-vinylmorpholine. , N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine and the like. .

Among the vinyl-based monomers having a nitrogen-containing heterocycle, acrylic monomers having a nitrogen-containing heterocycle are preferable, and (meth)acryloylmorpholine, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine are more preferable.

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

The (meth)acrylamides also include, for example, various N-hydroxyalkyl(meth)acrylamides. Examples of the N-hydroxyalkyl(meth)acrylamide 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 and the like.

The (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides. Examples of the N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

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

Among them, the nitrogen atom-containing monomer is preferably a cyclic nitrogen-containing monomer, and more preferably an N-vinyl cyclic amide. More specifically, N-vinyl-2-pyrrolidone (NVP) is particularly preferred.

When the acrylic polymer contains the nitrogen atom-containing monomer as a monomer component constituting the polymer, the proportion of the nitrogen atom-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is Although not particularly limited, it is preferably 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more. When the above ratio is 1% by weight or more, suppression of cloudiness and durability in a high-humidity environment can be further improved, and high adhesion reliability can be obtained, which is preferable. In addition, the upper limit of the ratio of the nitrogen atom-containing monomer is the point of obtaining a pressure-sensitive adhesive layer having moderate flexibility, the point of obtaining a pressure-sensitive adhesive layer with excellent transparency, the above-mentioned various properties of the pressure-sensitive adhesive layer (especially shear strength , glass transition point, etc.) is preferably 30% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less.

The monomer having a hydroxyl group in the molecule is a monomer having at least one hydroxyl group (hydroxyl group) in the molecule (in one molecule), and has an unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Those having a functional group and a hydroxyl group are preferred. However, the monomer having a hydroxyl group in 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 in the molecule is included in the above-mentioned "nitrogen atom-containing monomer". In this specification, the above-mentioned "monomer having a hydroxyl group in the molecule" may be referred to as "hydroxyl group-containing monomer". In addition, a hydroxyl-containing monomer can be used individually or in combination of 2 or more types.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, ( Hydroxyl group-containing (meth)acrylic acid 6-hydroxyhexyl, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxyllauryl (meth)acrylate, (meth)acrylic acid (4-hydroxymethylcyclohexyl), etc. meth)acrylic acid ester; vinyl alcohol; and allyl alcohol.

Among them, the hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylic acid ester, more preferably 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA).

When the acrylic polymer contains the hydroxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the hydroxyl group-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is particularly limited. However, it is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, from the viewpoint of suppressing clouding in a high-humidity environment, improving durability, and obtaining high adhesion reliability. , more preferably 1% by weight or more. Further, the upper limit of the ratio of the hydroxyl group-containing monomer is preferably 30% by weight or less from the viewpoint of facilitating control of the various properties of the pressure-sensitive adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range. It is preferably 25% by weight or less, and still more preferably 20% by weight or less.

For the purpose of further enhancing the effects of the hydroxyl group-containing monomer, the acrylic pressure-sensitive adhesive composition may contain a hydroxyl group-containing monomer in addition to the acrylic polymer. When the acrylic pressure-sensitive adhesive composition contains a hydroxyl group-containing monomer in addition to the acrylic polymer, the content (blended amount) of the hydroxyl group-containing monomer is 1 part by weight or more with respect to 100 parts by weight of the acrylic polymer. It is preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more. When the content is 5 parts by weight or more, suppression of cloudiness and durability in a high-humidity environment can be further improved, and higher adhesion reliability can be obtained, which is preferable. In addition, the upper limit of the content (blended amount) of the hydroxyl group-containing monomer is determined in terms of cohesive strength, adhesiveness, ease of obtaining adhesion reliability, and the above various properties of the pressure-sensitive adhesive layer (especially shear strength, glass transition point, etc.) 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. be.

The total ratio 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 suppresses clouding in a high-humidity environment. From the viewpoint of improving durability and obtaining high adhesion reliability, the content is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more. In addition, the upper limit of the total of the above ratios is the point of obtaining a pressure-sensitive adhesive layer having moderate flexibility, the point of obtaining a pressure-sensitive adhesive layer with excellent transparency, and the various properties of the pressure-sensitive adhesive layer (especially shear strength, glass transition points, etc.) is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less.

Copolymerizable monomers other than nitrogen atom-containing monomers and hydroxyl group-containing monomers further include alicyclic structure-containing monomers. The alicyclic structure-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and has an alicyclic structure. For example, an alkyl (meth)acrylate having a cycloalkyl group is included in the alicyclic structure-containing monomer. In addition, an alicyclic structure containing monomer can be used individually or in combination of 2 or more types.

The alicyclic structure in the alicyclic structure-containing monomer is a cyclic hydrocarbon structure, preferably having 5 or more carbon atoms, more preferably 6 to 24 carbon atoms, further preferably 6 to 15 carbon atoms, and 6 to 10 are particularly preferred.

Examples of the alicyclic structure-containing monomer include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, HPMPA represented by the following formula (2), TMA-2 represented by the following formula (3), HCPA represented by the following formula (4), etc. (Meth)acrylic monomers. In the following formula (4), there is no particular limitation on the bonding position between the cyclohexyl ring connected by a line and the structural formula in parentheses. Among these, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferred.

When the acrylic polymer contains the alicyclic structure-containing monomer as a monomer component constituting the polymer, the proportion of the alicyclic structure-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer. is not particularly limited, but is preferably 10% by weight or more from the viewpoint of improving durability and obtaining high adhesion reliability. In addition, the upper limit of the ratio of the alicyclic structure-containing monomer is determined to obtain a pressure-sensitive adhesive layer having appropriate flexibility, and the above-mentioned various properties of the pressure-sensitive adhesive layer (especially shear force, glass transition point, etc.) are set within a predetermined range. From the viewpoint of easy control, the content is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less.

Furthermore, copolymerizable monomers include, for example, polyfunctional monomers. Examples of the polyfunctional monomer 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 and the like. In addition, a polyfunctional monomer can be used individually or in combination of 2 or more types.

When the acrylic polymer contains the polyfunctional monomer as a monomer component constituting the polymer, the proportion of the polyfunctional monomer in the total monomer components (100% by weight) constituting the acrylic polymer is Although not particularly limited, from the viewpoint of easily controlling the above-mentioned various properties of the pressure-sensitive adhesive layer (in particular, shear force, glass transition point, etc.) within a predetermined range, 0.5% by weight or less (e.g., exceeding 0% by weight) 0.5% by weight or less), more preferably 0.2% by weight or less (for example, more than 0% by weight and 0.2% by weight or less).

Moreover, in addition to the said acrylic polymer, the said polyfunctional monomer may be mix|blended with an acrylic adhesive composition. When the acrylic pressure-sensitive adhesive composition contains a polyfunctional monomer in addition to the acrylic polymer, the content (blended amount) of the polyfunctional monomer is the pressure-sensitive adhesive layer per 100 parts by weight of the acrylic polymer. 0.5 parts by weight or less (e.g., more than 0 parts by weight and 0.5 parts by weight or less) is It is preferably 0.2 parts by weight or less (for example, more than 0 parts by weight and 0.2 parts by weight or less).

Moreover, (meth)acrylic-acid alkoxyalkyl ester is mentioned as said copolymerizable monomer. The (meth)acrylic acid alkoxyalkyl ester 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 and the like. Among them, the (meth)acrylic acid alkoxyalkyl ester is preferably an alkoxyalkyl acrylate, more preferably 2-methoxyethyl acrylate (MEA). The (meth)acrylic acid alkoxyalkyl esters may be used alone or in combination of two or more.

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

In addition, the copolymerizable monomers include, for example, carboxyl group-containing monomers, epoxy group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, aromatic hydrocarbon group-containing (meth)acrylic acid esters, vinyl esters, aromatic vinyl compounds, olefins or dienes, vinyl ethers, vinyl chloride and the like. Examples of the carboxyl group-containing monomers include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Examples of the carboxyl group-containing monomers include maleic anhydride. and anhydride group-containing monomers such as itaconic anhydride. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of the sulfonic acid group-containing monomer include sodium vinyl sulfonate. Phosphate group-containing monomers include, for example, 2-hydroxyethyl acryloyl phosphate. Examples of (meth)acrylic acid esters having an aromatic hydrocarbon group include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Examples of the vinyl esters include vinyl acetate and vinyl propionate. Examples of the aromatic vinyl compound include styrene and vinyltoluene. Examples of the olefins or dienes include ethylene, propylene, butadiene, isoprene, and isobutylene. Examples of the vinyl ethers include vinyl alkyl ethers.

From the viewpoint of obtaining an acrylic pressure-sensitive adhesive layer having excellent corrosion resistance, the acrylic polymer preferably does not contain or substantially does not contain an acidic group-containing monomer as a monomer component constituting the polymer, particularly a carboxyl group. It is preferably free or substantially free of contained monomers. Examples of acidic group-containing monomers include carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and the like. Specifically, the proportion of the acidic group-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is 0.05% by weight or less (preferably 0.01% by weight or less). can be said to be substantially free of

The content of the base polymer (especially acrylic polymer) in the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is 50% by weight or more (for example, 50 to 100% by weight), more preferably 80% by weight or more (eg, 80 to 100% by weight), and still more preferably 90% by weight or more (eg, 90 to 100% by weight).

The acrylic polymer has a weight average molecular weight (Mw) of 100,000 to 5,000,000, preferably 500,000 to 4,000,000, and more preferably 750,000 to 3,000,000. A configuration in which the weight-average molecular weight of the acrylic polymer is 100,000 or more is preferable from the viewpoint of improving adhesive strength and improving resistance to foaming and peeling. On the other hand, a configuration in which the weight average molecular weight of the acrylic polymer is 5,000,000 or less is preferable in terms of easily increasing adhesive strength and improving resistance to foaming and peeling.

The weight-average molecular weight (Mw) of the acrylic polymer can be determined by the GPC method in terms of polystyrene. For example, it can be measured under the following conditions using a high-speed GPC apparatus "HPLC-8120GPC" manufactured by Tosoh Corporation.
Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000
Solvent: Tetrahydrofuran Flow rate: 0.6 ml/min

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, still more preferably -60 to -20°C. When the glass transition temperature of the acrylic polymer is −70° C. or higher, the cohesive force is improved, and the resistance to foaming and peeling is easily improved, which is preferable. In addition, the structure in which the acrylic polymer has a glass transition temperature of −10° C. or lower maintains the stress relaxation property of the pressure-sensitive adhesive layer even in a low-temperature environment, and shrinks or expands in the environment in which the image display device of the present invention is used. It is preferable in that the pressure-sensitive adhesive layer sufficiently conforms to the surface, can suppress lifting and peeling, and can sufficiently ensure adhesion to the adherend.

The glass transition temperature (Tg) of the acrylic polymer is the glass transition temperature (theoretical value) represented by the following FOX formula.
₁ /Tg ₌ W1 _/ Tg1 ₊ W2/Tg2+...+ _Wn / _Tgn
In the above formula, Tg is the glass transition temperature (unit: K) of the acrylic polymer, Tg is the glass transition temperature (unit: K) when the monomer _i forms a homopolymer, and W is the total amount of the monomer component of the monomer _i . (i=1, 2, . . . n).
As the Tg of the homopolymer of the monomers constituting the acrylic polymer, the following values can be adopted.
2-ethylhexyl acrylate -70°C
n-hexyl acrylate -65°C
n-octyl acrylate -65°C
isononyl acrylate -60°C
n-nonyl acrylate -58°C
n-butyl acrylate -55°C
Ethyl acrylate -20°C
Lauryl acrylate 0°C
2-ethylhexyl methacrylate -10°C
Methyl acrylate 8°C
n-butyl methacrylate 20°C
Methyl methacrylate 105°C
Acrylic acid 106°C
Methacrylic acid 228°C
Vinyl acetate 32°C
Styrene 100°C

Further, as Tg of homopolymers of monomers not described above, values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) can be used. Furthermore, as the Tg of a homopolymer of a monomer not described in the above literature, the value obtained by the above-described measuring method (tan δ peak top temperature by viscoelasticity test) can be employed.

The base polymer such as the acrylic polymer contained in the pressure-sensitive adhesive layer of the present invention is obtained by polymerizing monomer components. The polymerization method is not particularly limited, but includes, for example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method using active energy ray irradiation (active energy ray polymerization method). Among these, the solution polymerization method and the active energy ray polymerization method are preferable, and the active energy ray polymerization method is more preferable, from the viewpoints of the transparency of the pressure-sensitive adhesive layer and the cost.

Moreover, various general solvents may be used in the polymerization of the above-mentioned monomer components. Examples of the solvent 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; cyclohexane, methylcyclohexane and the like. alicyclic hydrocarbons; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. In addition, a solvent can be used individually or in combination of 2 or more types.

Polymerization initiators such as thermal polymerization initiators and photopolymerization initiators (photoinitiators) may be used in the polymerization of the above monomer components depending on the type of polymerization reaction. In addition, a polymerization initiator can be used individually or in combination of 2 or more types.

Examples of the thermal polymerization initiator include, but are not limited to, azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), redox polymerization initiators, and the like. is mentioned. Among them, the azo polymerization initiator disclosed in JP-A-2002-69411 is preferable. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN"), 2,2'-azobis-2-methylbutyronitrile (hereinafter, " AMBN”), 2,2′-azobis(2-methylpropionate)dimethyl, 4,4′-azobis-4-cyanovaleric acid and the like. In addition, a thermal polymerization initiator can be used individually or in combination of 2 or more types.

When the azo polymerization initiator is used in the polymerization of the acrylic polymer, the amount of the azo polymerization initiator used is not particularly limited. , preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight It is below.

The photopolymerization initiator is not particularly limited. Active oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like can be mentioned. Other examples include acylphosphine oxide photopolymerization initiators and titanocene photopolymerization initiators. Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, anisole methyl ether and the like. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl ) and dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. be done. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the benzoin-based photopolymerization initiator include benzoin. Examples of the benzyl-based photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, and the like. Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. . Examples of the titanocene photopolymerization initiator include bis(η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl ) titanium and the like. In addition, a photoinitiator can be used individually or in combination of 2 or more types.

When the photopolymerization initiator is used in the polymerization of the acrylic polymer, the amount of the photopolymerization initiator used is not particularly limited. It is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less.

The acrylic pressure-sensitive adhesive composition preferably contains an acrylic oligomer having a weight average molecular weight of 1,000 to 30,000 together with the acrylic polymer. When the acrylic oligomer is contained, the adhesiveness to the adherend at the interface of the optical pressure-sensitive adhesive tape of the present invention is improved, so that it becomes easy to obtain strong adhesiveness and excellent resistance to foaming and peeling. Become. 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."

Examples of the acrylic oligomer include preferably acrylic polymers composed of a (meth)acrylic acid ester having a cyclic structure in the molecule as an essential monomer component, and a (meth)acrylic acid ester having a cyclic structure in the molecule. and an acrylic polymer composed of a (meth)acrylic acid alkyl ester having a linear or branched alkyl group as an essential monomer component is more preferable. That is, the acrylic oligomer preferably includes an acrylic polymer containing a (meth)acrylic acid ester having a cyclic structure in the molecule as a monomer unit, and (meth)acrylic acid having a cyclic structure in the molecule as a monomer unit. Acrylic polymers containing esters and (meth)acrylic acid alkyl esters having linear or branched alkyl groups are more preferred.

The cyclic structure (ring) of the (meth)acrylic acid ester having a cyclic structure in the molecule (in one molecule) (hereinafter sometimes referred to as "ring-containing (meth)acrylic acid ester") is an aromatic ring , a non-aromatic ring, and is not particularly limited. Examples of the aromatic ring include aromatic carbocyclic rings [eg, monocyclic carbocyclic rings such as benzene ring, condensed carbocyclic rings such as naphthalene ring, etc.], various aromatic heterocyclic rings, and the like. Examples of the non-aromatic ring include non-aromatic aliphatic rings (non-aromatic alicyclic rings) [e.g., cycloalkane rings such as cyclopentane ring, cyclohexane ring, cycloheptane ring, and cyclooctane ring cycloalkene rings such as cyclohexene rings], non-aromatic bridging rings [e.g., bicyclic hydrocarbon rings in pinane, pinene, bornane, norbornane, norbornene, etc.; tricyclic or higher aliphatic hydrocarbons in adamantane, etc. rings (bridged hydrocarbon rings, etc.)], non-aromatic heterocycles [eg, epoxy ring, oxolane ring, oxetane ring, etc.], and the like.

Examples of the tricyclic or higher aliphatic hydrocarbon ring (tricyclic or higher bridged hydrocarbon ring) include, for example, a dicyclopentanyl group represented by the following formula (5a), and a dicyclopentanyl group represented by the following formula (5b). a dicyclopentenyl group represented by the following formula (5c), an adamantyl group represented by the following formula (5d), a tricyclopentenyl group represented by the following formula (5d), a tricyclopentenyl group represented by the following formula (5e), and the like. .

That is, examples of the ring-containing (meth)acrylic acid ester include (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Acrylic acid cycloalkyl ester; (meth)acrylic acid ester having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth) Tricyclic or higher aliphatics such as acrylates, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate (Meth)acrylic acid esters having a hydrocarbon ring; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, (meth)acrylic acid aryloxyalkyl esters such as phenoxyethyl (meth)acrylate, (meth)acrylic acid esters Examples thereof include (meth)acrylic acid esters having an aromatic ring, such as (meth)acrylic acid arylalkyl esters such as benzyl acrylate. Among them, the ring-containing (meth)acrylic acid ester is particularly preferably a non-aromatic ring-containing (meth)acrylic acid ester, more preferably cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), acrylic They are dicyclopentanyl acid (DCPA) and dicyclopentanyl methacrylate (DCPMA), more preferably dicyclopentanyl acrylate (DCPA) and dicyclopentanyl methacrylate (DCPMA). In addition, ring-containing (meth)acrylic acid esters may be used alone or in combination of two or more.

Among the non-aromatic ring-containing (meth)acrylic acid esters, a (meth)acrylic acid ester having a tricyclic or higher aliphatic hydrocarbon ring (particularly, a tricyclic or higher bridging hydrocarbon ring) is used. This is particularly preferable in that polymerization inhibition is less likely to occur. Further, a dicyclopentanyl group having no unsaturated bond represented by the above formula (5a), an adamantyl group represented by the above formula (5c), and a tricyclopentanyl group represented by the above formula (5d) When using a (meth) acrylic acid ester having, it is possible to further increase the resistance to foaming and peeling, and furthermore, the adhesion to low-polar adherends such as polyethylene and polypropylene can be significantly improved. .

The content (percentage) of the ring-containing (meth)acrylic acid ester in the total monomer units of the acrylic oligomer (the total amount of the monomer components constituting the acrylic oligomer) is not particularly limited, but the total amount of the monomer components constituting the acrylic oligomer. (100 parts by weight), preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight. When the content of the ring-containing (meth)acrylic acid ester is 10 parts by weight or more, the resistance to foaming and peeling is easily improved, which is preferable. Moreover, when the content is 90 parts by weight or less, the pressure-sensitive adhesive layer has appropriate flexibility, and the pressure-sensitive adhesive strength, step absorbability, etc. are likely to be improved, which is preferable.

Examples of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group as a monomer unit of the acrylic oligomer include methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylate, ) propyl 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, (meth)acrylic acid nonyl, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate , pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. 1 to 20 (meth)acrylic acid alkyl esters and the like. Among them, methyl methacrylate (MMA) is preferable because it has good compatibility with the acrylic polymer. In addition, said (meth)acrylic-acid alkylester may be used individually or in combination of 2 or more types.

The content (percentage) of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group in the total monomer units of the acrylic oligomer (the total amount of the monomer components constituting the acrylic oligomer) is not particularly limited. , From the viewpoint of resistance to foaming and peeling, it is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, still more preferably 20 to 60 parts by weight, based on the total amount (100 parts by weight) of the monomer components constituting the acrylic oligomer. weight part. When the content is 10 parts by weight or more, the adhesive strength to an adherend made of acrylic resin or polycarbonate tends to be improved, which is preferable.

In addition to the above-mentioned ring-containing (meth)acrylic acid ester and (meth)acrylic acid alkyl ester having a linear or branched alkyl group, the monomer unit of the acrylic oligomer can be copolymerized with these monomers. monomers (copolymerizable monomers) may be contained. The content (percentage) of the copolymerizable monomer in the total monomer units of the acrylic oligomer (the total amount of the monomer components constituting the acrylic oligomer) is not particularly limited, but the total amount of the monomer components constituting the acrylic oligomer (100 parts by weight), preferably 49.9 parts by weight or less (eg, 0 to 49.9 parts by weight), more preferably 30 parts by weight or less. Also, the copolymerizable monomers may be used alone or in combination of two or more.

Examples of the copolymerizable monomer (the copolymerizable monomer constituting the acrylic oligomer) as monomer units of the acrylic oligomer include (meth)acrylic acid alkoxyalkyl ester [for example, (meth)acrylic acid 2-methoxy Ethyl, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxy (meth)acrylate butyl, 4-ethoxybutyl (meth)acrylate, etc.]; hydroxyl group (hydroxyl group)-containing monomers [e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth)acrylic acid 2 -Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, vinyl alcohol, allyl alcohol, etc.] ; amide group-containing monomers [e.g., (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N -hydroxyethyl (meth)acrylamide, etc.]; amino group-containing monomers [e.g., aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, etc.]; cyano group-containing monomers [e.g., acrylonitrile, methacrylonitrile, etc.]; sulfonic acid group-containing monomers [e.g., sodium vinyl sulfonate, etc.]; phosphoric acid group-containing monomers [e.g., 2-hydroxyethyl acryloyl phosphate, etc.]; isocyanate group-containing monomers [ 2-methacryloyloxyethyl isocyanate, etc.], imide group-containing monomers [cyclohexylmaleimide, isopropylmaleimide, etc.], and the like.

As described above, the acrylic oligomer is an acrylic polymer containing a (meth)acrylic acid ester having a cyclic structure in the molecule and a (meth)acrylic acid alkyl ester having a linear or branched alkyl group as monomer units. is preferably Among them, acrylic polymers containing, as monomer units, ring-containing (meth)acrylic acid esters and (meth)acrylic acid alkyl esters having a linear or branched alkyl group are preferred. In the acrylic polymer containing a ring-containing (meth)acrylic acid ester and a (meth)acrylic acid alkyl ester having a linear or branched alkyl group as the monomer unit, the total amount of monomer components constituting the acrylic oligomer (100 The amount of the ring-containing (meth)acrylic acid ester is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight. The content of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group is not particularly limited, but is preferably 10 to 90 parts by weight, more preferably 20 to 80 parts by weight, and even more preferably 20 to 60 parts by weight.

Furthermore, as a particularly preferred specific structure of the acrylic oligomer, the monomer unit is (1) at least one selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate. Acrylic polymers containing one monomer, as well as (2) methyl methacrylate. In the acrylic oligomer having the above-described particularly preferred specific configuration, (1) dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate are contained in all monomer units of the acrylic oligomer. The amount (the total amount of these when two or more are included) is 30 to 70 parts by weight with respect to the total amount of monomer components constituting the acrylic oligomer (100 parts by weight), and the content of (2) methyl methacrylate is It is preferably 30 to 70 parts by weight. However, the above acrylic oligomer is not limited to the above specific configuration.

The acrylic oligomer can be obtained by polymerizing the above monomer components by a known or commonly used polymerization method. Examples of the method for polymerizing the acrylic oligomer include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method using active energy ray irradiation (active energy ray polymerization method). Among them, the bulk polymerization method and the solution polymerization method are preferable, and the solution polymerization method is more preferable.

Various common solvents may be used in the polymerization of the acrylic oligomer. Examples of the solvent 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; cyclohexane, methylcyclohexane and the like. and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. In addition, such a solvent may be used individually or in combination of 2 or more types.

Furthermore, a known or commonly used polymerization initiator (for example, a thermal polymerization initiator, a photopolymerization initiator, etc.) may be used in the polymerization of the acrylic oligomer. In addition, a polymerization initiator may be used individually or in combination of 2 or more types.

Examples of thermal polymerization initiators include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis-2-methylbutyronitrile (AMBN), 2,2′-azobis(2- methylpropionate) 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) and other azo initiators; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1- Examples include peroxide-based initiators such as bis(t-butylperoxy)cyclododecane. In addition, when performing solution polymerization, it is preferable to use an oil-soluble polymerization initiator. Moreover, a thermal polymerization initiator may be used individually or in combination of 2 or more types.

The amount of the thermal polymerization initiator to be used is not particularly limited. is.

The photopolymerization initiator is not particularly limited, but includes, for example, the same photopolymerization initiator as the photopolymerization initiator used in the polymerization of the acrylic polymer mentioned above. The amount of the photopolymerization initiator to be used is not particularly limited, and is appropriately selected.

In the polymerization of the acrylic oligomer, a chain transfer agent may be used to adjust the molecular weight (specifically, to adjust the weight average molecular weight to 1000 to 30000). Examples of the chain transfer agent include 2-mercaptoethanol, α-thioglycerol, 2,3-dimercapto-1-propanol, octyl mercaptan, t-nonyl mercaptan, dodecyl mercaptan (lauryl mercaptan), t-dodecyl mercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene glycol thioglycolate, neopentyl glycol thioglycolate, pentaerythritol thioglycolate, α-methylstyrene dimer and the like. Among them, α-thioglycerol and methyl thioglycolate are preferable, and α-thioglycerol is particularly preferable, from the viewpoint of suppressing whitening of the optical pressure-sensitive adhesive tape of the present invention due to humidification. In addition, a chain transfer agent may be used individually or in combination of 2 or more types.

The content (amount used) of the chain transfer agent is not particularly limited, but is 0.1 to 20 parts by weight with respect to 100 parts by weight of the total monomer units of the acrylic oligomer (the total amount of the monomer components constituting the acrylic oligomer). is preferred, more preferably 0.2 to 15 parts by weight, and still more preferably 0.3 to 10 parts by weight. By setting the content (use amount) of the chain transfer agent within the above range, an acrylic polymer having a weight average molecular weight controlled to 1,000 to 30,000 can be easily obtained.

The acrylic oligomer has a weight average molecular weight (Mw) of 1,000 to 30,000, preferably 1,000 to 20,000, more preferably 1,500 to 10,000, and still more preferably 2,000 to 8,000. Since the acrylic oligomer has a weight-average molecular weight of 1000 or more, the adhesive strength and holding properties are improved, and the resistance to foaming and peeling is improved. On the other hand, since the acrylic oligomer has a weight average molecular weight of 30,000 or less, it is easy to increase the adhesive strength and improve the resistance to foaming and peeling.

The weight-average molecular weight (Mw) of the acrylic oligomer can be determined by GPC in terms of polystyrene. For example, it can be measured under the following conditions using a high-speed GPC apparatus "HPLC-8120GPC" manufactured by Tosoh Corporation.
Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000
Solvent: Tetrahydrofuran Flow rate: 0.6 ml/min

The glass transition temperature (Tg) of the acrylic oligomer is not particularly limited, but is preferably 20 to 300°C, more preferably 30 to 300°C, still more preferably 40 to 300°C. When the acrylic oligomer has a glass transition temperature of 20° C. or higher, the resistance to foaming and peeling is easily improved, which is preferable. In addition, when the glass transition temperature of the acrylic oligomer is 300° C. or less, the pressure-sensitive adhesive layer has appropriate flexibility, and it becomes easy to obtain good adhesive strength and good step absorbability, resulting in excellent adhesion reliability. It is easy to obtain, so it is preferable.

The glass transition temperature (Tg) of the acrylic oligomer is the glass transition temperature (theoretical value) represented by the FOX formula.
As the Tg of the homopolymer of the monomers constituting the acrylic oligomer, the values shown in Table 1 below can be used. As the Tg of homopolymers of monomers not listed in Table 1, values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) can be used. Furthermore, as the Tg of a homopolymer of a monomer not described in the above literature, the value obtained by the above-described measuring method (tan δ peak top temperature by viscoelasticity test) can be employed.

なお、表１における「ＤＣＰＭＡ／ＭＭＡ＝６０／４０」のコポリマーは、ＤＣＰＭＡ６０重量部とＭＭＡ４０重量部のコポリマーを意味する。

The copolymer "DCPMA/MMA=60/40" in Table 1 means a copolymer of 60 parts by weight of DCPMA and 40 parts by weight of MMA.

When the acrylic pressure-sensitive adhesive composition contains an acrylic polymer and an acrylic oligomer, the content of the acrylic oligomer is not particularly limited, but 1 to 30 parts by weight is used with respect to 100 parts by weight of the acrylic polymer. It is preferably 2 to 20 parts by weight, more preferably 2 to 10 parts by weight. That is, the content of the acrylic oligomer in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, based on 100 parts by weight of the total monomer units of the acrylic polymer. parts by weight, more preferably 2 to 10 parts by weight. The content of the acrylic oligomer in the acrylic pressure-sensitive adhesive composition is not particularly limited. Yes, more preferably 2 to 10 parts by weight. When the content of the acrylic oligomer is 1 part by weight or more, excellent adhesion and excellent resistance to foaming and peeling can be easily obtained, which is preferable. Further, when the content of the acrylic oligomer is 30 parts by weight or less, excellent transparency and adhesion reliability can be easily obtained, which is preferable. In addition, from the viewpoint of easily controlling the various properties of the pressure-sensitive adhesive layer (in particular, 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 8 parts by weight or less. is more preferred.

The method for producing the pressure-sensitive adhesive composition containing an acrylic polymer and an acrylic oligomer is not particularly limited. For example, 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) is added with an acrylic oligomer and an additive. etc. are added as necessary and mixed to prepare.

Although the pressure-sensitive adhesive layer of the present invention is not particularly limited, it preferably contains an ultraviolet absorber (UVA). When the pressure-sensitive adhesive layer of the present invention contains an ultraviolet absorber, it is preferable in that damage to the image display panel due to ultraviolet rays can be suppressed. In addition, an ultraviolet absorber can be used individually or in combination of 2 or more types.

The ultraviolet absorber is not particularly limited. Examples include benzophenone-based ultraviolet absorbers.

Benzotriazole-based UV absorbers (benzotriazole-based compounds) include, for example, 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name “TINUVIN PS”, manufactured by BASF), benzene Ester compound of propanoic acid and 3-(2H-benzotriazol-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-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[ A mixture of 3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2yl)phenyl]propionate (trade name “TINUVIN 109”, manufactured by BASF), 2-(2H-benzotriazole -2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name “TINUVIN 900”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6- (1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVIN 928”, manufactured by BASF), methyl 3-(3-(2H-benzotriazole -2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 reaction product (trade name “TINUVIN 1130”, manufactured by BASF), 2-(2H-benzotriazol-2-yl )-p-cresol (trade name “TINUVIN P”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF ), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name “TINUVIN 328”, manufactured by BASF), 2-(2H-benzotriazol-2-yl) -4-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVI N 329”, manufactured by BASF), 2,2′-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name “ TINUVIN 360", manufactured by BASF), a reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2-[2-hydroxy -3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name “Sumisorb 250” manufactured by Sumitomo Chemical Co., Ltd.), 2,2′-methylenebis[6- (2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name “ADEKA STAB LA-31”, manufactured by ADEKA Corporation) and the like.

Hydroxyphenyltriazine-based UV absorbers (hydroxyphenyltriazine-based compounds) include, for example, 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5 - Reaction product of 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-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4, Reaction product of 6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidate (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-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name “TINUVIN 1577”, manufactured by BASF), 2-(4,6-diphenyl-1 ,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name “ADEKA STAB LA-46”, manufactured by ADEKA Corporation), 2-(2 -Hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name “TINUVIN 479”, manufactured by BASF) and the like. be done. In addition, a compound represented by the following formula (6) (trade name “TINUVIN 477”, manufactured by BASF) can be used.

Benzophenone UV absorbers (benzophenone compounds) and oxybenzophenone 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.), 2,2′,4,4′-tetrahydroxybenzophenone (trade name “SEESORB 106”, manufactured by Sipro Kasei Co., Ltd.) , 2,2′-dihydroxy-4,4′-dimethoxybenzophenone and the like.

Salicylic acid ester-based ultraviolet absorbers (salicylic acid ester-based compounds) include, 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, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (trade name "TINUVIN 120", manufactured by BASF Corporation ) and the like.

Cyanoacrylate-based UV absorbers (cyanoacrylate-based compounds) include, for example, alkyl 2-cyanoacrylates, cycloalkyl 2-cyanoacrylates, alkoxyalkyl 2-cyanoacrylates, alkenyl 2-cyanoacrylates, alkynyl 2-cyanoacrylates, and the like. mentioned.

As the ultraviolet absorber, while having high ultraviolet absorption, corrosion resistance (in particular, UV resistance) is further improved, excellent optical properties, and ease of obtaining a pressure-sensitive adhesive layer having high transparency. 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, and benzo Triazole-based UV absorbers and benzophenone-based UV absorbers are more preferred. In particular, a benzotriazole-based ultraviolet absorber 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 is preferred.

In addition, the above ultraviolet absorber preferably has an absorbance A of 0.5 or less, which is obtained below, from the viewpoint of obtaining higher ultraviolet absorption and further improving corrosion resistance (especially UV resistance).
Absorbance A: Absorbance measured by applying light with a wavelength of 400 nm to a 0.08% toluene solution of the ultraviolet absorber

When the pressure-sensitive adhesive layer of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber in the pressure-sensitive adhesive layer (especially acrylic pressure-sensitive adhesive layer) of the present invention is not particularly limited, but corrosion resistance (especially , UV resistance), it is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.05 parts by weight or more per 100 parts by weight of the base polymer. It is 1 part by weight or more. In addition, the upper limit of the content of the ultraviolet absorber is to suppress the occurrence of yellowing of the adhesive due to the addition of the ultraviolet absorber, and to obtain excellent optical properties, high transparency, and excellent appearance characteristics. More preferably, it is 10 parts by weight or less, more preferably 9 parts by weight or less, and even more preferably 8 parts by weight or less, relative to 100 parts by weight of the base polymer.

The pressure-sensitive adhesive layer of the invention may contain a light stabilizer. When the pressure-sensitive adhesive layer of the present invention contains a light stabilizer, it is particularly preferable to contain the light stabilizer together with the ultraviolet absorber. The light stabilizer can scavenge radicals generated by photo-oxidation, and thus can improve the resistance of the pressure-sensitive adhesive layer to light (especially ultraviolet rays). In addition, a light stabilizer can be used individually or in combination of 2 or more types.

The light stabilizer is not particularly limited. Stabilizers (amine compounds) (especially hindered amine stabilizers (hindered amine compounds)) and the like.

Examples of the phenolic light stabilizer (phenolic compound) include 2,6-di-tertiary-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tertiary-butylphenol, 2, 6-di-tertiary-butyl-4-ethylphenol, butylated hydroxyanisole, n-octadecyl 3-(4-hydroxy-3,5-di-tertiary-butylphenyl) propionate, distearyl (4-hydroxy- 3-methyl-5-tertiary-butyl)benzylmalonate, tocopherol, 2,2′-methylenebis(4-methyl-6-tertiary-butylphenol), 2,2′-methylenebis(4-ethyl-6-tertiary tertiary butylphenol), 4,4'-methylenebis (2,6-di-tertiary butylphenol), 4,4'-butylidenebis (6-tertiary butyl-m-cresol), 4,4'-thiobis ( 6-tertiary-butyl-m-cresol), styrenated phenol, N,N'-hexamethylenebis(3,5-di-tertiary-butyl-4-hydroxyhydrocinnamide, bis(3,5-di -tert-butyl-4-hydroxybenzylphosphonic acid ethyl ester) calcium, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl -2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy methyl]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-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate acid, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, triethylene glycol-bis[3-(3-tert-butyl-4-hydroxy-5 -methylphenyl)propionate], 2,2′-oxamide bis[ethyl 3-(3,5-di-tert-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-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 3,9-bis{2-[3-(3-tert-butyl-4 -hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 3,9-bis{2-[3-( 3,5-di-tertiary-butyl-4-hydroxyphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane and the like.

Phosphorus-based light stabilizers (phosphorus-based compounds) include, for example, trisnonylphenyl phosphite, 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)penta Erythritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6- Di-tertiary-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tertiary-butylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite phyte, tetra(tridecyl)-4,4'-n-butylidenebis(2-tertiary-butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy -5-tertiary-butylphenyl)butane triphosphite, tetrakis(2,4-di-tertiary-butylphenyl)biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide, tris(2-[(2,4,8,10-tetrakis-tertiary-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl ) amines and the like.

Thioether-based light stabilizers (thioether-based compounds) include, for example, dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl and distearyl; polyol β such as tetrakis[methylene(3-dodecylthio)propionate]methane; -alkylmercaptopropionate ester compounds, and the like.

Examples of amine light stabilizers (amine compounds) include polymers of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name “TINUVIN 622”, BASF Co.), 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-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine and 1:1 reaction product (trade name "TINUVIN 119", manufactured by BASF), dibutylamine 1,3-triazine N, N'-bis (2,2,6,6-tetramethyl-4- Polycondensate of 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) A mixture of sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 765", manufactured by BASF), bis(2,2,6,6-tetramethyl-4- piperidyl) sebacate (trade name “TINUVIN 770”, manufactured by BASF), decanedioic acid bis (2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester, 1,1-dimethyl Reaction product of ethyl hydroperoxide and octane (trade name “TINUVIN 123”, manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1, 1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (trade name “TINUVIN 144”, manufactured by BASF), cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidine Reaction product of amine-2,4,6-trichloro-1,3,5-triazine product and 2-aminoethanol reaction product (trade name “TINUVIN 152”, manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2, A mixture of 2,6,6-pentamethyl-4-piperidyl sebacate (trade name “TINUVIN 292”, manufactured by BASF), 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6 -Pentamethyl-4-piperidinol and mixed ester with 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (trade name "ADEKA STAB LA-63P", manufactured by ADEKA Co., Ltd.) and the like. Hindered amine stabilizers are particularly preferred as amine stabilizers.

When the pressure-sensitive adhesive layer of the present invention contains a light stabilizer, the content of the light stabilizer in the pressure-sensitive adhesive layer of the present invention (particularly, the acrylic pressure-sensitive adhesive layer) is not particularly limited, but resistance to light is improved. From the viewpoint of facilitating expression, it is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, relative to 100 parts by weight of the base polymer. In addition, the upper limit of the content is 5 parts by weight or less with respect to 100 parts by weight of the base polymer, from the viewpoints that coloring due to the light stabilizer itself is unlikely to occur, high transparency is easily obtained, and optical properties are obtained. is preferred, and more preferably 3 parts by weight or less.

The formation of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but a cross-linking agent may be used. For example, the gel fraction can be controlled by cross-linking the acrylic polymer in the acrylic pressure-sensitive adhesive layer. In addition, a crosslinking agent can be used individually or in combination of 2 or more types.

The cross-linking agent is not particularly limited. cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, amine-based cross-linking agents, and the like. Among them, isocyanate-based cross-linking agents and epoxy-based cross-linking agents are preferable, and isocyanate-based cross-linking agents are more preferable.

Examples of the isocyanate-based cross-linking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate; , cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate and other alicyclic polyisocyanates; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and aromatic polyisocyanates such as xylylene diisocyanate. Examples of the isocyanate-based cross-linking agent include trimethylolpropane/tolylene diisocyanate adduct (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (trade name Commercially available products such as "Coronate HL", manufactured by Nippon Polyurethane Industry Co., Ltd., and trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc.) can also be used.

Examples of the epoxy-based cross-linking agent (polyfunctional epoxy compound) include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidyl aminomethyl)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, adipate diglycidyl ester, o-phthalate diglycidyl ester, triglycidyl-tris(2 -hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy-based cross-linking agent include commercially available products such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

When a cross-linking agent is used to form the pressure-sensitive adhesive layer of the present invention, the amount of the cross-linking agent used is not particularly limited. 001 parts by weight or more, more preferably 0.01 parts by weight or more. In addition, the upper limit of the amount used is that the pressure-sensitive adhesive layer can obtain appropriate flexibility and improve the adhesive strength, and the above-mentioned various properties (especially shear strength, glass transition point, etc.) of the pressure-sensitive adhesive layer can be adjusted to predetermined levels. From the viewpoint of easy control within the range, it is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, relative to 100 parts by weight of the base polymer.

The pressure-sensitive adhesive layer (especially acrylic pressure-sensitive adhesive layer) of the present invention contains a silane coupling agent in order to improve adhesion reliability under humidified conditions, particularly to improve adhesion reliability to glass. may In addition, a silane coupling agent can be used individually or in combination of 2 or more types. When the pressure-sensitive adhesive layer contains a silane coupling agent, the adhesiveness under humidified conditions, particularly the adhesiveness to glass, can be improved.

Examples of the silane coupling agent include, but are not limited to, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltri methoxysilane and the like. Furthermore, as the silane coupling agent, for example, commercially available products such as the product name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be mentioned. Among them, γ-glycidoxypropyltrimethoxysilane is preferable as the silane coupling agent.

When the pressure-sensitive adhesive layer of the present invention contains a silane coupling agent, the content of the silane coupling agent in the pressure-sensitive adhesive layer (particularly, the acrylic pressure-sensitive adhesive layer) of the present invention is not particularly limited, but the above It is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, relative to 100 parts by weight of the base polymer. The upper limit of the content of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, relative to 100 parts by weight of the base polymer.

The pressure-sensitive adhesive layer of the invention may contain an antistatic agent. In addition, an antistatic agent can be used individually or in combination of 2 or more types. When the pressure-sensitive adhesive layer contains an antistatic agent, damage to an adherend such as an image display panel can be prevented.

Examples of the antistatic agent include quaternary ammonium salts, pyridinium salts, cationic antistatic agents having cationic functional groups such as primary, secondary, and tertiary amino groups, sulfonates, sulfate ester salts, and phosphonic acids. Salts, anionic antistatic agents having anionic functional groups such as phosphate ester salts, alkylbetaines and their derivatives, imidazoline and its derivatives, amphoteric antistatic agents such as alanine and its derivatives, aminoalcohols and their derivatives, glycerin and derivatives thereof, nonionic antistatic agents such as polyethylene glycol and derivatives thereof, and further, obtained by polymerizing or copolymerizing monomers having the above cationic, anionic, and amphoteric ion conductive groups Ion-conducting polymers can be mentioned.

When the pressure-sensitive adhesive layer of the present invention contains an antistatic agent, the content of the antistatic agent in the pressure-sensitive adhesive layer of the present invention is not particularly limited. 01 parts by weight or more, more preferably 0.02 parts by weight or more. The upper limit of the content of the antistatic agent is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, relative to 100 parts by weight of the base polymer.

The pressure-sensitive adhesive layer of the invention may contain a coloring agent. In addition, a coloring agent can be used individually or in combination of 2 or more types. When the pressure-sensitive adhesive layer contains a coloring agent, it is preferable in that reflection due to metal wiring, ITO wiring, or the like arranged on the substrate of the image display device of the present invention can be prevented.

The coloring agent may be either a dye or a pigment as long as it can be dissolved or dispersed in the pressure-sensitive adhesive layer of the present invention. Dyes are preferred because they can achieve a low haze even when added in a small amount, and are easy to distribute uniformly without sedimentation like pigments. Pigments are also preferred because they have high color development even when added in small amounts. If a pigment is used as the colorant, it preferably has low or no conductivity. Moreover, when using a dye, it is preferable to use together with said light stabilizer.

As the coloring agent, as long as it absorbs visible light (wavelength 400 to 700 nm), it is not limited to those exhibiting transparency to ultraviolet rays (wavelength 330 to 400 nm) or those exhibiting absorbency to ultraviolet rays. Although they can be used, those that absorb visible light and have UV transparency are preferred. That is, it is preferable that the coloring agent has a maximum transmittance at a wavelength of 330 to 400 nm larger than a maximum transmittance at a wavelength of 400 to 700 nm. It is also preferable that the coloring agent has a higher average transmittance at wavelengths of 330 to 400 nm than at wavelengths of 400 to 700 nm. The transmittance of the colorant is adjusted by an appropriate solvent such as tetrahydrofuran (THF) or a dispersion medium (organic solvent with low absorption in the wavelength range of 330 to 700 nm) so that the transmittance at a wavelength of 400 nm is about 50 to 60%. Measure using diluted solutions or dispersions.

Carbon black and titanium black, which are generally used as black colorants, absorb more ultraviolet rays than visible light (the ultraviolet transmittance is smaller than the visible light transmittance). Therefore, when a coloring agent such as carbon black is added to an active energy ray-curable acrylic pressure-sensitive adhesive composition, most of the ultraviolet rays irradiated for photocuring are absorbed by the coloring agent, and the amount of light absorbed by the photopolymerization initiator is is small, and photocuring takes time (accumulated amount of irradiation light increases). In addition, when the thickness of the pressure-sensitive adhesive layer is large, less ultraviolet rays reach the surface opposite to the light irradiation surface, so that photocuring tends to be insufficient even if light irradiation is performed for a long time. On the other hand, by using a coloring agent having a higher transmittance for ultraviolet light than for visible light, it is possible to suppress curing inhibition caused by the coloring agent.

Examples of ultraviolet-transmitting black pigments include "9050BLACK" and "UVBK-0001" manufactured by Tokushiki. Examples of ultraviolet-absorbing black dyes include "VALIFAST BLACK 3810" and "NUBIAN Black PA-2802" manufactured by Orient Chemical Industries. Examples of ultraviolet absorbing black pigments include carbon black and titanium black.

The content of the colorant in the pressure-sensitive adhesive layer of the present invention is, for example, about 0.01 to 20 parts by weight with respect to 100 parts by weight of the base polymer. It may be appropriately set according to the transmittance or the like. Colorants may be added to the composition as a solution or dispersion dissolved or dispersed in a suitable solvent.

The pressure-sensitive adhesive layer of the present invention may optionally further contain a cross-linking accelerator, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), an antioxidant, a filler, an antioxidant, a chain Additives such as migrating agents, plasticizers, softening agents, and surfactants may be contained within a range that does not impair the effects of the present invention. In addition, such additives can be used individually or in combination of 2 or more types.

The haze of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less in terms of appearance properties, transparency, and optical properties. . In addition, in this specification, the haze of an adhesive layer can be measured according to JISK7136 using a haze meter, for example.

Although the total light transmittance of the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 85% or more, more preferably 90% or more, and still more preferably 92% in terms of appearance properties, transparency, and optical properties. That's it. In this specification, the total light transmittance of the pressure-sensitive adhesive layer can be measured according to JIS K 7361-1 using, for example, a haze meter. The above total light transmittance is the transmittance of light (visible light) having a wavelength of 400 to 780 nm.

Although the thickness of the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 12 µm or more, preferably 15 µm or more, more preferably 20 µm or more, and particularly preferably 70 µm or more from the viewpoint of obtaining sufficient adhesion reliability. . When the thickness is 12 μm or more, the pressure-sensitive adhesive layer sufficiently follows contraction or expansion under the usage environment of the image display device of the present invention, which is preferable in that lifting and peeling can be suppressed. The thickness is preferably 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less, from the viewpoint of optical properties.

<Manufacture of optical adhesive tape>
The optical pressure-sensitive adhesive tape of the present invention can be prepared by laminating the pressure-sensitive adhesive layer of the present invention on the first surface of the substrate of the present invention.

The method for laminating the pressure-sensitive adhesive layer of the present invention on the first surface of the base material of the present invention is not particularly limited. By drying and curing the adhesive composition layer, or by applying (coating) the adhesive composition on the separator and curing the obtained adhesive composition layer by irradiating it with an active energy ray, on the separator It can be carried out by molding into a sheet-like pressure-sensitive adhesive layer, and laminating the pressure-sensitive adhesive layer on the first surface of the substrate of the present invention. Moreover, you may heat-dry further as needed.
When curing by irradiation with active energy rays, a separator is further attached to the surface of the coating film, and the adhesive composition is sandwiched between two separators and irradiated with active energy rays to polymerize with oxygen. It is preferred to prevent inhibition.

Another method for laminating the pressure-sensitive adhesive layer of the present invention on the first surface of the substrate of the present invention is, for example, applying (coating) the above-mentioned pressure-sensitive adhesive composition onto the first surface of the substrate of the present invention. , drying and curing the obtained pressure-sensitive adhesive composition layer, or applying (coating) the above-mentioned pressure-sensitive adhesive composition on the first surface of the substrate of the present invention, and applying an active agent to the obtained pressure-sensitive adhesive composition layer. It can also be cured by irradiation with energy rays. Moreover, you may heat-dry further as needed.
When curing by irradiation with active energy rays, a separator is attached to the surface of the coating film, and the adhesive composition is irradiated with active energy rays while being sandwiched between the base material of the present invention and the separator. It is preferable to prevent polymerization inhibition by oxygen.

Before the active energy ray irradiation, the sheet-like coating film may be heated for the purpose of removing the solvent or the like. If the solvent or the like is removed by heating, it is preferably performed before attaching the separator.

Examples of the active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron beams and electron beams, and ultraviolet rays, and ultraviolet rays are particularly preferred. Moreover, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, etc. are not particularly limited.

The pressure-sensitive adhesive composition can be produced by a known or commonly used method. For example, a solvent-based acrylic pressure-sensitive adhesive composition can be prepared by mixing an additive (for example, an ultraviolet absorber, etc.) with a solution containing the acrylic polymer, if necessary. For example, an active energy ray-curable acrylic pressure-sensitive adhesive composition can be prepared by mixing an additive (for example, an ultraviolet absorber, etc.) with the mixture of acrylic monomers or a partial polymer thereof, if necessary. can be made.

In addition, you may utilize a well-known coating method for application|coating of the said adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters and direct coaters may be used.

In particular, when the adhesive layer is formed from an active energy ray-curable adhesive composition, the active energy ray-curable adhesive composition preferably contains a photopolymerization initiator. When the active energy ray-curable pressure-sensitive adhesive composition contains an ultraviolet absorber, it preferably contains at least a photopolymerization initiator having light absorption properties in a wide wavelength range as a photopolymerization initiator. For example, it preferably contains at least a photopolymerization initiator that absorbs not only ultraviolet light but also visible light. This is because there is concern that curing by active energy rays may be inhibited due to the action of the ultraviolet absorber, and if the adhesive composition contains a photopolymerization initiator that has light absorption characteristics in a wide wavelength range, high photocurability will be achieved in the adhesive composition. This is because it becomes easier to obtain.

<Antistatic layer>
The optical pressure-sensitive adhesive tape of the present invention may have an antistatic layer on the surface or between any layers. Since the optical pressure-sensitive adhesive tape of the present invention has an antistatic layer, damage to adherends such as image display panels can be prevented. The antistatic layer is preferably formed between the substrate of the present invention and the adhesive layer of the present invention.

The antistatic layer is not particularly limited, but is, for example, an antistatic layer formed by coating a separator with a conductive coating liquid containing a conductive polymer. Specifically, for example, it is an antistatic layer formed by coating the first surface of the substrate of the present invention with a conductive coating liquid containing a conductive polymer. Specific coating methods include a roll coating method, a bar coating method, a gravure coating method, and the like.

Examples of the conductive polymer include a conductive polymer obtained by doping a π-conjugated conductive polymer with a polyanion. Examples of π-conjugated conductive polymers include linear conductive polymers such as polythiophene, polypyrrole, polyaniline, and polyacetylene. Polyanions include polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallylsulfonic acid, polyethyl acrylate sulfonic acid, polymethacrylic carboxylic acid, and the like.

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

<Separator>
In the optical pressure-sensitive adhesive tape of the present invention, the surface of the pressure-sensitive adhesive layer of the present invention (adhesive surface of the pressure-sensitive adhesive layer of the present invention) may be protected by a separator until use. The separator is used as a protective material for the pressure-sensitive adhesive layer, and is peeled off when the optical pressure-sensitive adhesive tape of the present invention is applied to an adherend.

As the separator, a conventional release paper or the like can be used. Specifically, for example, in addition to a substrate having a release treatment layer with a release treatment agent on at least one surface, a fluorine-based polymer (e.g., polytetrafluoroethylene) , polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.). A low-adhesive base material made of (for example, an olefin resin such as polyethylene or polypropylene) can be used.

As the separator, for example, a separator in which a release treatment layer is formed on at least one surface of a separator substrate can be suitably used. Base materials for such separators include polyester film (polyethylene terephthalate film, etc.), olefin resin film (polyethylene film, polypropylene film, etc.), polyvinyl chloride film, polyimide film, polyamide film (nylon film), rayon film, etc. In addition to the plastic base film (synthetic resin film) and paper (wooden paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top coat paper, etc.), these are multi-layered by lamination or co-extrusion. (composite of 2 to 3 layers) and the like.

The release agent that constitutes the release layer is not particularly limited, but for example, a silicone release agent, a fluorine release agent, a long-chain alkyl release agent, or the like can be used. The release agents can be used alone or in combination of two or more.

The thickness of the separator is not particularly limited, and may be appropriately selected from the range of 5 to 100 μm.

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

The antistatic layer is not particularly limited, but is, for example, an antistatic layer formed by coating a separator with a conductive coating liquid containing a conductive polymer. Specifically, for example, it is an antistatic layer formed by coating a separator (release-treated surface and/or untreated surface) with a conductive coating liquid containing a conductive polymer. Specific coating methods include a roll coating method, a bar coating method, a gravure coating method, and the like.

As the conductive polymer, the same conductive polymer as that constituting the antistatic layer constituting the optical pressure-sensitive adhesive tape of the present invention can be used.

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

<Surface protection film>
In the optical pressure-sensitive adhesive tape of the present invention, the second surface of the substrate of the present invention may be protected with a surface protection film. The surface protective film is used as a protective material for the second surface of the base material of the present invention during the production and transport of the optical pressure-sensitive adhesive tape of the present invention, the image display device of the present invention, and the tiling display of the present invention. be.

Materials for forming the surface protective film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymers thereof. Resin etc. are mentioned. Ester-based resins (especially polyethylene terephthalate-based resins) are preferred.

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

The surface protective film is releasably attached to the second surface of the base material of the present invention via any appropriate adhesive. Preferably, a surface protection film having an adhesive layer formed thereon is formed, and this is attached to the second surface of the substrate of the present invention of the optical pressure-sensitive adhesive tape of the present invention. The adhesive used for lamination of the surface protective film includes, for example, an acrylic resin, a styrene resin, a silicone resin, or the like as a base resin, and the base resin is selected from isocyanate compounds, epoxy compounds, aziridine compounds, and the like. A pressure-sensitive adhesive composition containing a cross-linking agent, a silane coupling agent, or the like may be used. The thickness of the adhesive layer is usually 1 μm to 60 μm, preferably 3 μm to 30 μm. If the pressure-sensitive adhesive layer is too thin, there is a risk that problems such as reduced adhesiveness and that air bubbles will easily enter may occur. Acrylic pressure-sensitive adhesives are preferably used from the viewpoint of chemical resistance, adhesion, and the like.

<Image display device>
The image display device of the present invention has a laminate structure in which the optical pressure-sensitive adhesive tape of the present invention and an image display panel are laminated. In FIG. 3, an image display device 20 has an image display panel 4 laminated on an adhesive layer 1 of an optical adhesive tape 10B.

Since the image display device of the present invention has the optical pressure-sensitive adhesive tape of the present invention in its laminated structure, it can be suppressed from shrinking or expanding under the environment of use, and can maintain its transparency without change. In addition, the pressure-sensitive adhesive layer of the present invention sufficiently follows contraction or expansion of the image display device, and is less likely to lift or peel off. Furthermore, when the image display panel has uneven steps due to wiring or the like, the pressure-sensitive adhesive layer of the present invention can sufficiently follow the steps and can be filled without leaving air bubbles.

Examples of the image display panel include, but are not limited to, a liquid crystal image display panel, a self-luminous image display panel (eg, an organic EL (electroluminescence) image display panel, an LED image display panel), and the like.

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

The image display device of the present invention may have an optical member other than the optical pressure-sensitive adhesive tape of the present invention and the image display panel on the surface or between any layers. Examples of the optical member include, but are not particularly limited to, a polarizing plate, a retardation plate, an antireflection film, a viewing angle adjusting film, and an optical compensation film. Note that the above-mentioned optical members include members (design films, decorative films, surface protection plates, etc.) that play a role of decoration and protection while maintaining the visibility of the image display device and the input device.

The image display device of the present invention can be produced by laminating the image display panel and the pressure-sensitive adhesive layer of the optical pressure-sensitive adhesive tape of the present invention.

Specifically, the image display panel and the optical pressure-sensitive adhesive tape of the present invention can be attached by laminating under heat and/or pressure. Curing may be performed by irradiating active energy rays after lamination under heat and/or pressure. Irradiation with active energy rays can be performed in the same manner as in the formation of the pressure-sensitive adhesive layer of the present invention.

<Tiling display>
A 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 laminated structure is not shown) in a 3×3 array in a tile shape on a support substrate 31 . They are in contact with each other with a gap 32 between them. As the support substrate, the same glass plate or plastic film as the substrate of the present invention can be used.

Since the image display device of the present invention is suppressed from shrinking or expanding under the usage environment, it is difficult for gaps or overlaps to occur between the plurality of image display devices in the tiling display of the present invention, and the gaps are less conspicuous. Appearance is maintained. Furthermore, there is little shrinkage or expansion, and transparency can be maintained without change. In addition, the pressure-sensitive adhesive layer of the present invention can sufficiently follow the contraction or expansion of the image display device, and can prevent problems caused by lifting or peeling.

Further, in the tiling display of the present invention, when the second surface of the substrate of the present invention is subjected to antireflection treatment and/or antiglare treatment, metal wiring arranged on the substrate of the image display device of the present invention It is preferable in that it can prevent the reflection due to the ITO wiring or the like. Moreover, in a tiling display, it is also preferable in that the gap between the image display devices of the present invention becomes less visible.

The tiling display of the present invention may include members other than the image display device of the present invention and the support substrate. Examples of such members include, but are not particularly limited to, backlights and touch sensors.

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 the outermost surface by sealing with glass or the like.

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

Production example 1
(Preparation of antiglare film 1)
[Preparation of coating solution for forming antiglare layer 1]
As the resin contained in the antiglare layer forming material, 40 parts by weight of an ultraviolet curable urethane acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Oligo UA-53H-80BK”) and pentaerythritol triacrylate are the main components. A diluted solution of a composition for an optical adjustment layer containing 57.5 parts by weight of a polyfunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name “Viscoat #300”), zirconia particles, and an ultraviolet curable resin (“Opstar Z7540", manufactured by JSR Corporation) 2.5 parts by weight, silicone particles (manufactured by Momentive Performance Materials Japan LLC, trade name "Tospearl 130ND") 2.8 parts by weight, and organic clay as a thixotropy imparting agent A certain synthetic smectite (manufactured by Kunimine Industries Co., Ltd., trade name "Smecton SAN") 2.5 parts by weight, a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907") 3 parts by weight, and a crosslinked acrylic styrene copolymer resin 6.5 parts by weight of fine particles (manufactured by Sekisui Plastics Co., Ltd., trade name "SSX-103DXE") and a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., trade name "LE-303") 0.1 parts by weight. . The organic clay was used after being diluted with toluene so that the solid content was 6% by weight. This mixture is diluted with a toluene/cyclopentanone (CPN) mixed solvent (weight ratio 64/36) so that the solid content concentration is 38% by weight, and an antiglare layer is formed using an ultrasonic disperser. A material (coating liquid) was prepared.

[Formation of antiglare layer 1]
As a substrate, a transparent plastic film substrate (PET film, manufactured by Toray Industries, Inc., trade name “38U413”, thickness: 38 μm) was prepared. The antiglare layer-forming material (coating liquid) was applied to one side of the transparent plastic film substrate using a wire bar to form a coating film (coating step). Then, the coating film was dried by heating at 95° C. for 1 minute (drying step). After that, ultraviolet light was irradiated with an integrated light amount of 300 mJ/cm ² from a high-pressure mercury lamp to cure the coating film to form an antiglare layer having a thickness of 6.5 μm. Thus, a laminate of the light transmissive substrate and the antiglare layer 1 was obtained.

[Preparation of coating solution for forming antireflection layer 1]
100 parts by weight of polyfunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name “Viscoat #300”) mainly composed of pentaerythritol triacrylate, and hollow nano silica particles (manufactured by Nikki Shokubai Kasei Kogyo Co., Ltd., trade name “Sururia 5320") 100 parts by weight, solid nanosilica particles (manufactured by Nissan Chemical Industries, Ltd., trade name "MIBK-ST", solid content 30% by weight, weight average particle diameter 10 nm) 40 parts by weight, fluorine element-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203") 12 parts by weight, a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907") 5 parts by weight, a photopolymerization initiator (manufactured by BASF, (product name "OMNIRAD2959")) was mixed with 5 parts by weight. To this mixture, a mixed solvent of MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) mixed at a weight ratio of 70:30 was added as a dilution solvent so that the total solid content was 1.5% by weight. and stirred to prepare a coating solution for forming an antireflection layer.
[Formation of antireflection layer 1]
The antireflection layer-forming coating liquid was applied to the antiglare layer surface of the laminate of the light transmissive substrate and the antiglare layer 1 with a wire bar (coating step). The applied coating liquid was heated at 80° C. for 1 minute and dried to form a coating film (drying step). After drying, the coating film was cured by irradiating ultraviolet light with an accumulated light amount of 300 mJ/cm ² from a high-pressure mercury lamp (curing step). Thus, the coating film was cured to form an antireflection layer 1 having a thickness of 0.1 μm (antireflection layer forming step). Antiglare film 1 of Production Example 1 was produced as described above.

Production example 2
(Preparation of antiglare film 2)
[Formation of antiglare layer 2]
In the preparation of the antiglare layer-forming coating liquid, the blending amount of the polyfunctional acrylate containing pentaerythritol triacrylate as a main component was changed to 60 parts by weight, and the blending amount of the silicone particles was changed to 0.9 parts by weight. 1.5 parts by weight of synthetic smectite, which is an organic clay, as a thixotropy-imparting agent; a diluted solution of a composition for an optical adjustment layer containing zirconia particles and an ultraviolet curable resin; A laminate of the light transmissive substrate and the antiglare layer 2 was produced in the same manner as in Production Example 1, except that the fine particles of acrylic styrene copolymer resin were not used.
[Formation of antireflection layer 2]
An antireflection layer 2 was formed in the same manner as in Production Example 1, except that the blending amount of the hollow nanosilica particles was changed to 240 parts by weight in the preparation of the coating solution for forming the antireflection layer. Antiglare film 2 of Production Example 2 was produced as described above.

Production example 3
(Preparation of antiglare film 3)
In the formation of the antiglare layer, the same method as in Production Example 1 except that a transparent plastic film substrate (COP film, manufactured by Nippon Zeon Co., Ltd., trade name "ZF14", thickness: 50 μm) was used as the substrate. The anti-glare film 3 of this production example 3 was produced.

Production example 4
(Preparation of antiglare film 4)
In the formation of the antiglare layer, the same method as in Production Example 1 was used, except that a transparent plastic film substrate (PEN film, manufactured by Toyobo Co., Ltd., trade name "Q51", thickness: 25 µm) was used as the substrate. An antiglare film 4 of Production Example 4 was produced.

Production example 5
(Preparation of antiglare film 5)
In the formation of the antiglare layer, the same method as in Production Example 1 was used, except that a transparent plastic film substrate (PEEK film, manufactured by Kurabo Industries, Ltd., trade name "EXPEEK", thickness: 50 µm) was used as the substrate. Antiglare film 5 of Production Example 5 was produced.

Production example 6
(Manufacture of transparent plastic film substrate)
Isosorbide (hereinafter sometimes abbreviated as "ISB") 81.98 parts by mass, tricyclodecane dimethanol (hereinafter sometimes abbreviated as "TCDDM") 47.19 parts by mass, diphenyl carbonate (hereinafter "DPC") 175.1 parts by mass and 0.979 parts by mass of a 0.2% by mass cesium carbonate aqueous solution as a catalyst are charged into a reaction vessel, and the first stage of the reaction is performed under a nitrogen atmosphere. As the second step, the temperature of the heating bath was heated to 150° C., and the raw materials were dissolved with stirring as necessary (about 15 minutes). Next, the pressure was changed from normal pressure to 13.3 kPa, and the generated phenol was discharged out of the reaction vessel while raising the heating bath temperature to 190° C. in 1 hour. After holding the entire reaction vessel at 190°C for 15 minutes, as the second step, the pressure inside the reaction vessel was increased to 6.67 kPa, the heating tank temperature was raised to 230°C in 15 minutes, and the generated phenol was removed. It was pulled out of the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and the pressure in the reaction vessel was made to reach 0.200 kPa or less in order to remove the generated phenol. After reaching a predetermined stirring torque, the reaction was terminated, and the produced reactant was extruded into water to obtain polycarbonate resin pellets. After vacuum drying the obtained polycarbonate resin at 80 ° C. for 5 hours, a single screw extruder (manufactured by Shibaura Machine Co., Ltd., cylinder set temperature: 250 ° C.), T die (width 300 mm, set temperature: 250 ° C.), Using a film forming apparatus equipped with a chill roll (set temperature: 120 to 130° C.) and a winder, a transparent plastic film substrate made of polycarbonate resin and having a thickness of 40 μm was produced.
(Preparation of antiglare film 6)
Antiglare film 6 of Production Example 6 was prepared in the same manner as in Production Example 1, except that the transparent plastic film substrate composed of the polycarbonate resin obtained above was used as the substrate in the formation of the antiglare layer. manufactured.

Production example 7
(Preparation of antiglare film 7)
In the formation of the antiglare layer, the main production was performed in the same manner as in Production Example 1, except that a transparent plastic film substrate (CPI film, manufactured by KOLON, trade name "C_50_D", thickness: 50 µm) was used as the substrate. An antiglare film 7 of Example 7 was produced.

Production example 8
(Preparation of antiglare film 8)
The same method as in Production Example 1 except that a transparent plastic film substrate (TAC film, manufactured by Fuji Film Co., Ltd., trade name "TD80UL", thickness: 80 µm) was used as the substrate in forming the antiglare layer. The antiglare film 8 of Production Example 8 was produced in the above manner.

Production example 9
(Preparation of acrylic pressure-sensitive adhesive composition 1)
[Preparation of acrylic oligomer]
60 parts by weight of dicyclopentanyl 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 are mixed. and stirred at 70° C. for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2′-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, reacted at 70° C. for 2 hours, and then heated to 80° C. for 2 hours. reacted. After that, the reaction solution was heated to 130° C., and the toluene, the chain transfer agent and the unreacted monomer were removed by drying to obtain a solid acrylic oligomer (acrylic oligomer A). The acrylic oligomer A had a weight average molecular weight of 5100 and a glass transition temperature (Tg) of 130°C.

[Preparation of prepolymer and acrylic pressure-sensitive adhesive composition 1]
As monomer components for forming the 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 N-vinyl-2-pyrrolidone (NVP ) 10 parts by weight, and 0.1 parts by weight of BASF's "Omnirad 184" and 0.1 parts by weight of BASF's "Omnirad 651" as photopolymerization initiators, and polymerized by irradiating ultraviolet rays to form a prepolymer composition. Obtained. To 100 parts by weight of the above prepolymer composition, 37 parts by weight of 2-ethylhexyl acrylate (2EHA) and 1,6-hexanediol diacrylate (trade name "A-HD-N", Shin-Nakamura Chemical Co., Ltd.) were added as post-addition components. company), 6 parts by weight of the above acrylic oligomer A, and 0.3 parts by weight of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd. "KBM403"). A system adhesive composition 1 was prepared.

Production example 10
(Preparation of prepolymer and acrylic pressure-sensitive adhesive composition 2)
As monomer components for forming a prepolymer, 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (“Viscoat #155” manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 19 parts by weight of 4-hydroxybutyl acrylate (4HBA), and As a photopolymerization initiator, 0.09 parts by weight of "Omnirad 184" manufactured by BASF and 0.09 parts by weight of "Omnirad 651" manufactured by BASF were blended and polymerized by irradiating ultraviolet rays to obtain a prepolymer composition. 9 parts by weight of hydroxyl ethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 0.02 parts by weight of dipentaerythritol hexaacrylate (DPHA) as post-addition components to 100 parts by weight of the above prepolymer composition. part, a photopolymerization initiator (manufactured by BASF "Omnirad651") 0.3 parts by weight, and a silane coupling agent (manufactured by Shin-Etsu Chemical "KBM403") After adding 0.35 parts by weight, these are uniformly mixed, An acrylic pressure-sensitive adhesive composition 2 was prepared.

Production example 11
(Preparation of prepolymer and acrylic pressure-sensitive adhesive composition 3)
78 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of hydroxyl ethyl acrylate (HEA), and 18 parts by weight of N-vinyl-2-pyrrolidone (NVP) as monomer components for forming a prepolymer, and as a photopolymerization initiator 0.035 parts by weight of "Omnirad 184" manufactured by BASF and 0.035 parts by weight of "Omnirad 651" manufactured by BASF were blended and polymerized by irradiation with ultraviolet rays to obtain a prepolymer composition. To 100 parts by weight of the above prepolymer composition, 17.6 parts by weight of hydroxyl ethyl acrylate (HEA) and 1,6-hexanediol diacrylate (trade name "A-HD-N", Shin-Nakamura Chemical Co., Ltd.) were added as post-addition components. Co., Ltd.) 0.294 parts by weight, 11.8 parts by weight of the above acrylic oligomer A, and 0.35 parts by weight of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd. "KBM403") were added, and these were uniformly mixed. Thus, an acrylic pressure-sensitive adhesive composition 3 was prepared.

Example 1
(Preparation of substrate-less pressure-sensitive adhesive layer 1)
A polyethylene terephthalate (PET) film ("Diafoil MRF75" manufactured by Mitsubishi Chemical) having a thickness of 75 μm and having a silicone-based release layer on the surface is used as a base material (double release film). A coating layer was formed by applying the acrylic pressure-sensitive adhesive composition 1 to a thickness of 25 μm. A release layer of a 75 μm-thick PET film (“Diafoil MRE75” manufactured by Mitsubishi Chemical Co., Ltd.) having one side subjected to silicone release treatment as a cover sheet (also a light release film) was laminated on the coating layer. From the cover sheet side, this laminate is irradiated with ultraviolet rays by a black light whose position is adjusted so that the irradiation intensity on the irradiation surface directly below the lamp is 5 mW/cm ² , and photocuring is performed. An adhesive layer 1 was obtained.
(Preparation of adhesive tape 1)
By attaching the exposed adhesive surface by peeling off one of the release films from the substrate-less adhesive layer 1 obtained above to the non-antiglare layer surface of the antiglare film 1 shown in Production Example 1, An adhesive tape 1 consisting of antiglare film 1/adhesive layer 1/release film was obtained.

Example 2
(Preparation of adhesive tape 2)
Adhesive tape 2 consisting of antiglare film 2/adhesive layer 1/release film was obtained in the same manner as in Example 1, except that antiglare film 2 described above was used.

Example 3
(Preparation of base-less pressure-sensitive adhesive layer 2)
A substrate-less pressure-sensitive adhesive layer 2 having a thickness of 25 μm was obtained in the same manner as in Example 1, except that the acrylic pressure-sensitive adhesive composition 2 described above was used.
(Preparation of adhesive tape 3)
Adhesive tape 3 consisting of antiglare film 1/adhesive layer 2/release film was obtained in the same manner as in Example 1, except that the substrate-less adhesive layer 2 obtained above was used.

Example 4
(Preparation of adhesive tape 4)
Adhesive tape 4 consisting of antiglare film 3/adhesive layer 1/release film was obtained in the same manner as in Example 1, except that antiglare film 3 described above was used.

Example 5
(Preparation of adhesive tape 5)
Adhesive tape 5 consisting of antiglare film 4/adhesive layer 1/release film was obtained in the same manner as in Example 1 except that antiglare film 4 described above was used.

Example 6
(Preparation of adhesive tape 6)
Adhesive tape 6 consisting of antiglare film 5/adhesive layer 1/release film was obtained in the same manner as in Example 1 except that antiglare film 5 described above was used.

Example 7
(Preparation of adhesive tape 7)
Adhesive tape 7 consisting of antiglare film 6/adhesive layer 1/release film was obtained in the same manner as in Example 1 except that antiglare film 6 described above was used.

Example 8
(Preparation of adhesive tape 8)
Adhesive tape 8 consisting of antiglare film 7/adhesive layer 1/release film was obtained in the same manner as in Example 1, except that antiglare film 7 described above was used.

Comparative example 1
(Preparation of adhesive tape 9)
Adhesive tape 9 consisting of antiglare film 8/adhesive layer 1/release film was obtained in the same manner as in Example 1 except that antiglare film 8 described above was used.

Comparative example 2
(Preparation of base-less pressure-sensitive adhesive layer 3)
A substrate-less pressure-sensitive adhesive layer 3 having a thickness of 25 μm was obtained in the same manner as in Example 1, except that the acrylic pressure-sensitive adhesive composition 3 described above was used.
(Preparation of adhesive tape 10)
Adhesive tape 10 consisting of antiglare film 8/adhesive layer 3/release film was obtained in the same manner as in Example 1 except that antiglare film 8 and substrate-less adhesive layer 3 described above were used. rice field.

(evaluation)
The following evaluations were performed using the adhesive tapes obtained in the above Examples and Comparative Examples. The evaluation method is shown below. Table 2 shows the results.

(1) Average dimensional change The adhesive tape prepared in each example and each comparative example was cut into a substantially square shape of 100 mm in the MD direction × 100 mm in the TD direction in plan view, and each of the four corners was scratched in a cross pattern. to prepare a test piece.
In the test piece (25 ° C.) before heating, the distance (length) between the MD directions of the scratches (cross pattern center) and the distance (length) between the TD directions were measured with a CNC three-dimensional measuring machine (Mitutoyo Co., Ltd.) Measured at room temperature (25° C.) using “LEGEX774” manufactured by Thereby, the length before heating was obtained in each of the MD direction and the TD direction.
Then, the test piece was heated in an environment of 60° C. and relative humidity of 90% for 500 hours, and then allowed to cool at room temperature (25° C.) for 1 hour. After that, the distance between the scratches in the MD direction and the distance between the scratches in the TD direction were measured with a CNC three-dimensional measuring machine. Thereby, the length after heating was obtained in each of the MD direction and the TD direction. Next, the dimensional change rates A1 and A2 were calculated in each of the MD and TD directions according to the following equations, and the average value was defined as the average dimensional change rate (%). Also, the ratio (A1/A2) of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction was determined.

Dimensional change rate (%) = [length after heating (mm) - length before heating (mm)] / length before heating (mm) x 100

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

(2) Maximum amount of curl The release film of the adhesive tape prepared in each example and each comparative example was peeled off, and a PET film (manufactured by Mitsubishi Chemical Corporation, trade name “Diafoil T100E50”, thickness: 50 μm) was attached. The obtained laminate was cut into a substantially square shape of 100 mm×100 mm in plan view to prepare a test piece.
Then, the test piece was heated in an environment of 60° C. and relative humidity of 90% for 500 hours, and then allowed to cool at room temperature (25° C.) for 1 hour. After that, it was placed on a horizontal surface so that the convex surface of the curl was on the bottom, and the distance was measured from the horizontal surface at four corner points. The distance from the horizontal surface to the longest point was taken as the maximum amount of curl (mm). .
The maximum curl amount measured by placing the laminate on a horizontal surface with the PET film side facing down is +, and the base side of the laminate (opposite side of the PET film) is down. The maximum amount of curl was measured by placing it on a horizontal surface so as to be equal to -.

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

(4) Haze The pressure-sensitive adhesive tapes obtained in each example and each comparative example were measured at room temperature (23° C.) using a haze measuring device (HR-100 manufactured by Murakami Color Laboratory). Measurement was repeated 3 times, and the average value was used as the measured value.

(5) Shear force of the adhesive layer The adhesive tape obtained in each example and comparative example was cut into a size of 10 mm in width and 100 mm in length, and after peeling off the separator, the adhesive layer of the adhesive tape adhered ( Bonded) so that the area is 1 cm ² , it was attached to an acrylic resin plate (Acrylite, manufactured by Mitsubishi Chemical), pulled in the shear direction at a peeling rate of 0.06 mm / min at 23 ° C., and the maximum load at that time (N / cm ² ) was taken as the shear force.

(6) Storage modulus, loss tangent, and glass transition temperature of the adhesive layer The separator was peeled from the adhesive layer obtained in each example and comparative example, and a plurality of adhesive layers were laminated. , about 2 mm thick test samples were made. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to dynamic viscoelasticity measurement under the following conditions using "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific. From the results, the storage modulus G' and the loss tangent tan δ at each temperature were read. Further, the temperature at which tan δ becomes maximum was defined as the glass transition temperature of the pressure-sensitive adhesive layer.
(Measurement condition)
Deformation mode: Torsion Measurement frequency: 1Hz
Measurement temperature: -70°C to 150°C

(7) 300% tensile residual stress value of the adhesive layer The adhesive layer obtained in each example and comparative example was cut into a size of 40 mm × 40 mm, and the separator on one side was peeled off. Then, the separator on one side was peeled off again, and the adhesive surfaces were again attached to each other to prepare an adhesive layer sample having a size of about 10 mm x 40 mm and a thickness of about 400 µm. The pressure-sensitive adhesive layer sample was set in a tensile tester with a chuck-to-chuck distance of 20 mm, and pulled by 60 mm (300%) at a tensile speed of 200 mm/min (chuck-to-chuck distance after stretching was 80 mm). It was fixed and held for 300 seconds at a position where it was pulled by 60 mm, and the stress value after that was measured, and the "300% tensile residual stress value" was calculated from the following formula.

300% tensile residual stress value (N/cm ² )=stress value after fixed and held for 300 seconds (N)/(4×adhesive sheet thickness (mm)/10)

(8) Strain amount A, strain amount B, and recovery rate The separator is peeled off from the adhesive layer obtained in each example and comparative example, and a plurality of adhesive layers are laminated to form a test sample having a thickness of about 2 mm. was prepared, and this test sample was punched into a disk shape with a diameter of 7.9 mm to obtain a sample. A shear test for obtaining the "strain amount A", "strain amount B", and "restoration rate" was performed in the form shown in FIG. Specifically, using Rheometric Scientific's "Advanced Rheometric Expansion System (ARES)" having parallel plates 41 and 42 with a diameter of 7.9 mm, the upper surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are respectively attached to the sample. The bottom surface and the top surface of the pressure-sensitive adhesive layer were aligned and brought into contact (Fig. 5(b)). Next, dynamic viscoelasticity measurement was performed under the following measurement conditions. The amount B was read, and the recovery rate was calculated by the following formula.
(Measurement condition)
Deformation mode: Torsion Measurement program: Hold 500 Pa for 600 seconds, then hold 0 Pa for 1800 seconds.
Measurement temperature: 60°C
Axial Force: 0.2N
Restoration rate: (distortion amount A−distortion amount B)/distortion amount A×100

(9) Humidity expansion coefficient The adhesive tapes obtained in each example and comparative example were cut into 2 mm width in the TD direction and 20 mm length in the MD direction, and the HC-TMA4000SA type manufactured by Bruker AXS Co. The measurement was performed according to the conditions.
(Measurement condition)
Deformation mode: Tensile Load: 2g
Holding time: 5 hours Heating rate: 5% RH/min
Measurement atmosphere: maintained until saturation at 60°C relative humidity 30%, controlled to 60°C relative humidity 60%

(10) Humidity expansion coefficient of substrate Humidity expansion coefficient is measured by using HC-TMA4000SA type manufactured by Bruker AXS and measuring the elongation of each film when the humidity is changed from 30% RH to 60% RH at 60 ° C. (unit: /RH%).
The humidity expansion coefficient (α) was calculated by the following formula.
α = ΔL / {(T2-T1) × L}
T1: Low humidity side humidity (% RH) for obtaining the humidity expansion coefficient
T2: High-humidity side humidity (% RH) for obtaining the humidity expansion coefficient
ΔL: difference between the length of the test piece at T1 and the length at T2 (μm)
L: Length of test piece at room temperature (60°C) (μm)

(11) Glass transition point (Tg) of substrate
About 8 mg of a sample was collected, placed in an aluminum container, and subjected to DSC measurement.
Equipment: TA Instruments Q-2000
Container: Aluminum container Temperature program: -30°C → 300°C
Heating rate: 10°C/min
Atmospheric gas: N ₂ (50 ml/min)

(12) Confirmation of gaps between adhesive tapes The adhesive tapes obtained in Examples and Comparative Examples were cut into 5 cm × 5 cm pieces and attached without gaps on glass, and heated at 60 ° C. and a relative humidity of 90% for 500 hours. After that, it was allowed to cool at room temperature (25° C.) for 1 hour. After that, the glass was placed on the backlight, and the gap between the adhesive tapes was visually observed and evaluated according to the following criteria when the backlight was irradiated.
Good: No gaps between the adhesive tapes were observed.
×: A gap between the adhesive tapes was confirmed

(13) Confirmation of Peeling of Adhesive Adhesive The edge of the adhesive tape of the sample heated at 60° C. and 90% relative humidity for 500 hours, which was used to confirm the gap between the adhesive tapes, was observed with an optical microscope and evaluated according to the following criteria.
Good: Peeling of the adhesive tape was not observed.
× Peeling was confirmed on the adhesive tape

Variations of the present invention are described below.
[Appendix 1] An optical adhesive tape having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer is laminated on the first surface of the substrate,
The average dimensional change in the width direction and the machine direction when the optical pressure-sensitive adhesive tape is heated for 500 hours in an environment of 60° C. and a relative humidity of 90% is within ±0.15%,
An optical disc having a shear force of 20 N/cm ² or less when an adhesive area of 1 cm ² of the adhesive layer is attached to a resin plate and pulled at 23° C. in the shear direction at a tensile speed of 0.06 mm/min. Adhesive tape for
[Appendix 2] C [%] is the average dimensional change rate in the width direction and the machine direction when the optical pressure-sensitive adhesive tape is heated in an environment of 60° C. and 90% relative humidity for 500 hours,
The following maximum curl amount when the laminate obtained by laminating the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and then cutting it into a 10 cm square was heated for 500 hours at 60° C. and a relative humidity of 90%. The optical pressure-sensitive adhesive tape according to Appendix 1, which satisfies the following formula, where D [mm].

|C×D|≦3

・Maximum amount of curl: The laminate is placed on a horizontal plane with the convex surface of the curl facing downward, and the maximum amount of curl D [mm] is defined as the highest warpage at the four corners. The maximum curl amount measured by placing the laminate on a horizontal surface with the PET film side facing down was measured by placing the laminate on a horizontal surface with the substrate side facing down. The maximum amount of curl is -.
[Appendix 3] The optical pressure-sensitive adhesive tape according to Appendix 1 or 2, wherein the substrate has a glass transition point (Tg) of 60° C. or higher.
[Appendix 3] The optical pressure-sensitive adhesive tape according to any one of Appendices 1 to 3, wherein the pressure-sensitive adhesive layer has a glass transition point (Tg) of −10° C. or lower.
[Appendix 5] Any one of Appendices 1 to 4, wherein the optical pressure-sensitive adhesive tape has a humidity expansion rate of 0.1% or less when humidified from 60° C. relative humidity 30% to 60° C. relative humidity 60%. Optical adhesive tape as described.
[Appendix 6] The optical pressure-sensitive adhesive tape according to any one of Appendices 1 to 5, wherein the substrate has a humidity expansion coefficient of 5×10 ⁻⁵ /% RH or less.
[Appendix 7] The optical pressure-sensitive adhesive tape according to any one of Appendices 1 to 6, wherein the second surface of the substrate is subjected to antireflection treatment and/or antiglare treatment.
[Appendix 8] The optical pressure-sensitive adhesive tape according to any one of Appendices 1 to 7, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer.
[Appendix 9] An image display device in which the optical pressure-sensitive adhesive tape according to any one of Appendices 1 to 8 and an image display panel are laminated.
[Appendix 10] A tiling display in which a plurality of image display devices according to Appendix 9 are arranged.

10A, 10B optical pressure-sensitive adhesive tape 1 substrate 1a substrate first surface 1b substrate second surface 2 adhesive layer 3 antireflection treatment and/or antiglare treatment 20 image display device 4 image display panel 30 tiling display 31 Support substrate 40 Adhesive layers 41 and 42 Parallel plate

Claims (10)

An optical pressure-sensitive adhesive tape having a laminated structure in which a substrate having a first surface and a second surface and an adhesive layer is laminated on the first surface of the substrate,
The average dimensional change in the width direction and the machine direction when the optical pressure-sensitive adhesive tape is heated for 500 hours in an environment of 60° C. and a relative humidity of 90% is within ±0.15%,
An optical disc having a shear force of 20 N/cm ² or less when an adhesive area of 1 cm ² of the adhesive layer is attached to a resin plate and pulled at 23° C. in the shear direction at a tensile speed of 0.06 mm/min. Adhesive tape for C [%] is the average dimensional change rate in the width direction and the machine direction when the optical pressure-sensitive adhesive tape is heated for 500 hours in an environment of 60 ° C. and 90% relative humidity,
The following maximum curl amount when the laminate obtained by laminating the adhesive layer of the optical adhesive tape to a PET film having a thickness of 50 μm and then cutting it into a 10 cm square was heated for 500 hours at 60° C. and a relative humidity of 90%. The optical pressure-sensitive adhesive tape according to claim 1, which satisfies the following formula when D [mm].

|C×D|≦3

・Maximum amount of curl: The laminate is placed on a horizontal plane with the convex surface of the curl facing downward, and the maximum amount of curl D [mm] is defined as the highest warpage at the four corners. The maximum curl amount measured by placing the laminate on a horizontal surface with the PET film side facing down was measured by placing the laminate on a horizontal surface with the substrate side facing down. The maximum amount of curl is -. The optical pressure-sensitive adhesive tape according to claim 1 or 2, wherein the substrate has a glass transition point (Tg) of 60°C or higher. The optical pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a glass transition point (Tg) of -10°C or lower. The optical adhesive tape according to any one of claims 1 to 4, wherein the adhesive tape for optical use has a humidity expansion rate of 0.1% or less when humidified from 30% relative humidity at 60°C to 60% relative humidity at 60°C. Adhesive tape for The optical pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein the substrate has a humidity expansion coefficient of 5 x 10 ^-5 /% RH or less. The optical pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the second surface of said substrate is antireflection-treated and/or anti-glare-treated. The optical pressure-sensitive adhesive tape according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer. An image display device comprising a laminate of the optical pressure-sensitive adhesive tape according to any one of claims 1 to 8 and an image display panel. A tiling display in which a plurality of image display devices according to claim 9 are arranged.

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