KR20230136743A - Optical adhesive tape - Google Patents

Abstract

The present invention relates to a tiling display in which a plurality of image display devices are arranged in a tile shape, in which the gap between the plurality of image display devices is difficult to notice even under the usage environment, transparency can be maintained, and a good appearance is maintained. The purpose is to provide an adhesive tape for optical use. The optical adhesive tape (10A) of the present invention includes a substrate (1) having a first side (1a) and a second side (1b), and an adhesive layer (2) on the first side (1a) of the substrate (1). It has a stacked layered structure. The average dimensional change rate in the width direction and machine direction when the optical adhesive tape 10A is heated for 500 hours in an environment of 60°C and 90% relative humidity is within ±0.15%. When an adhesive area of 1 cm 2 of the adhesive layer 2 is bonded to a resin plate and stretched in the shear direction at a tensile speed of 0.06 mm/min at 23° C., the shear force is 20 N/cm 2 or less.

Description

Optical adhesive tape

The present invention relates to an adhesive tape for optics. In detail, it relates to an optical adhesive tape suitable for manufacturing a tiling display in which a plurality of image display devices are arranged in a tile form.

With the increase in image quality such as 4K and 8K, the demand for image display devices with larger screens is increasing. In addition, the use of large-screen image display devices for advertising displays outdoors, in public facilities, etc., and for signage such as bulletin boards is also progressing. However, when manufacturing a large-screen image display device, problems arise such as lower yields and increased manufacturing costs. In order to manufacture large-screen image display devices at lower cost, a tiling display that arranges a plurality of image display devices in tiles is being studied (for example, patent document 1).

Japanese Patent Publication No. 2017-161634

In a tiling display, it is necessary to narrow the gap between a plurality of image display devices (e.g., 100 μm or less) in order to make it less conspicuous. However, under the usage environment, the image display devices contract or expand, causing the gap to become smaller. There is a problem in that a small gap or a slight overlap of the image display device occurs, causing a gap to be noticeable, transparency is lowered, and the appearance is poor. Additionally, there was a problem that the adhesive layer that bonds the optical members constituting the image display device could not keep up with the contraction and expansion of the image display device, causing lifting or peeling at the ends, and deteriorating the appearance.

The present invention was conceived based on the above-mentioned circumstances, and the object of the present invention is to provide a tiling display in which a plurality of image display devices are arranged in tiles, even under the usage environment, between the plurality of image display devices. The object is to provide an optical adhesive tape that makes it difficult for gaps to be noticeable, can maintain transparency, and maintains a good appearance.

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

The optical adhesive tape of the first aspect of the present invention has an average dimensional change rate of within ±0.15% in the width direction and 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 on which the optical adhesive tape of the first aspect of the present invention is laminated is arranged, and shrinkage under the use environment of the image display device is achieved. Alternatively, it is suitable in that expansion is suppressed, gaps between image display devices are suppressed from being noticeable, good appearance is maintained, shrinkage or expansion is small, and transparency can be maintained without change. In order to prevent the gap between image display devices from being noticeable, to reduce shrinkage or expansion, and to maintain transparency without change, the average dimensional change rate is preferably within ±0.1%, and may be within ±0.05%. do.

In the optical adhesive tape of the first aspect of the present invention, when an adhesive area of 1 cm 2 of the adhesive layer is bonded to a resin plate and stretched in the shear direction at a tensile speed of 0.06 mm/min at 23° C., the shear force is 20 N/min. It is less than ㎠. In this specification, “shear force” refers to “the force applied when 1 cm2 of the adhesive layer of the adhesive layer is bonded to a resin plate and stretched in the shear direction at a tensile speed of 0.06 mm/min at 23°C,” unless otherwise specified. It shall represent “shear force.”

The configuration in which the shear force of the adhesive layer is 20 N/cm2 or less allows the adhesive layer to sufficiently follow the contraction or expansion under the use environment of the image display device on which the optical adhesive tape of the first aspect of the present invention is laminated, and does not float. This is desirable because it can suppress peeling. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. In order to suppress the lifting or peeling of the optical adhesive tape of the first aspect of the present invention and to be able to follow a level difference, the shear force of the adhesive layer is preferably 15 N/cm 2 or less, and may be 13 N/cm 2 or less.

Let C[%] be the average dimensional change rate in the width direction and 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,

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

|C×D|≤3

· Maximum curl amount: The laminate is placed on a horizontal surface so that the convex curled surface is at the bottom, and the highest curl amount among the four corners is taken as the maximum curl amount D [mm]. The maximum amount of curl measured with the PET film side of the above-mentioned laminate placed on a horizontal plane facing down is +, and the maximum curl amount measured with the base material side of the above-mentioned laminate placed on a horizontal surface facing down is taken as -.

The configuration in which the absolute value of the product of the average dimensional change rate C [%] and the maximum curl amount D [mm] |C A tiling display in which a plurality of devices are arranged in a row is suitable because it is difficult to visually recognize changes in the gap between the image display devices and the image display devices can be bonded to a film substrate with high precision. Since it is difficult to recognize changes in the gap between the image display devices and the image display device can be bonded to the film substrate with high precision, the |C×D| is preferably 2.5 or less, more preferably 2.4 or less. , may be 2.3 or less, or 2.2 or less.

In the optical adhesive tape of the first aspect of the present invention, the glass transition point (Tg) of the substrate is preferably 60°C or higher. The configuration in which the glass transition point of the substrate is 60°C or higher is such that, in the tiling display in which a plurality of image display devices on which the optical adhesive tape of the first aspect of the present invention is laminated is arranged, the mechanical properties of the image display device under the use environment are It is desirable in that it is stable. From the viewpoint of stability of 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 adhesive tape of the first aspect of the present invention, the glass transition point (Tg) of the adhesive layer is preferably -10°C or lower. The configuration in which the Tg of the adhesive layer is -10°C or lower maintains the stress relaxation property of the adhesive layer even in a low-temperature environment, and the use environment of the image display device on which the optical adhesive tape of the first aspect of the present invention is laminated This is preferable because the adhesive layer sufficiently follows contraction or expansion under pressure, can suppress lifting or peeling, and can sufficiently secure adhesion to the adherend. From the viewpoint of suppressing lifting or peeling in the image display device and providing good adhesion to an adherend, the glass transition point of the adhesive layer is preferably -15°C or lower, and may be -20°C or lower.

When the optical adhesive tape of the first aspect of the present invention is humidified from a relative humidity of 30% at 60°C to a relative humidity of 60% at 60°C, the humidity expansion rate is preferably 0.1% or less. The configuration in which the humidity expansion rate is 0.1% or less suppresses expansion of the image display device due to moisture absorption in the tiling display in which a plurality of image display devices on which the optical adhesive tape of the first aspect of the present invention is laminated is arranged. , it is suitable in that the gap between the image display devices is suppressed from being noticeable, shrinkage or expansion is small, and transparency can be maintained without change. From the viewpoint of suppressing expansion of the image display device due to moisture absorption, reducing shrinkage or expansion, and maintaining transparency without change, the humidity expansion rate is preferably 0.08% or less, and may be 0.06% or less.

In the optical adhesive tape of the first aspect of the present invention, the humidity expansion coefficient of the substrate is preferably 5×10 ^-5 /%RH or less. The configuration in which the humidity expansion coefficient of the substrate is ⁵ In a tiling display in which a plurality of display devices are arranged, shrinkage or expansion of the image display devices is suppressed under a use environment, gaps between image display devices are suppressed from being noticeable, and a good appearance is maintained. It is suitable in that it has little expansion and transparency can be maintained without change. In terms of dimensional stability of the substrate, there is little shrinkage or expansion, and transparency can be maintained without change, the humidity expansion coefficient of the substrate is preferably 3 × 10 ^-5 /%RH or less, and 2 × 10 ^-5 / It may be %RH or less.

In the optical adhesive tape of the first aspect of the present invention, the second surface of the substrate is preferably treated with anti-reflection treatment and/or anti-glare treatment. A configuration in which the second surface of the substrate is subjected to anti-reflection treatment and/or anti-glare treatment is preferable in that reflection by metal wiring, ITO wiring, etc. disposed on the substrate of the image display device can be prevented. Furthermore, in a tiling display in which a plurality of image display devices on which the optical adhesive tape of the first aspect of the present invention is laminated is arranged, it is also preferable in that the gap between the image display devices becomes difficult to be recognized.

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

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

Since the image display device of the second aspect of the present invention has the optical adhesive tape of the first aspect of the present invention in a laminated structure, shrinkage or expansion under a use environment can be suppressed. Furthermore, even when the image display device of the second aspect of the present invention contracts or expands to some extent, the adhesive layer sufficiently follows the contraction or expansion of the image display device, so that lifting or peeling is unlikely to occur. 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 gap between the image display devices is less noticeable under the usage environment and has a good appearance. It can be maintained. Additionally, transparency can be maintained without change.

By using the optical adhesive tape of the present invention in the production of a tiling display in which a plurality of image display devices are arranged, shrinkage or expansion of the image display device under the usage environment can be suppressed, so that the gap between the image display devices is reduced. It is difficult to stand out and maintains a good appearance. Additionally, transparency can be maintained without change. Additionally, even when the image display device expands or contracts to a certain extent, it is difficult for the adhesive layer to float or peel off, making it possible to efficiently manufacture a high-performance tiling display.

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

A first aspect of the present invention provides an optical adhesive tape having a laminated structure in which a substrate has a first side and a second side, and an adhesive layer is laminated on the first side of the substrate.

The optical adhesive tape of the first side of the present invention may be referred to as “the optical adhesive tape of the present invention” in this specification. In addition, in this specification, the said base material and adhesive layer which comprise the optical adhesive tape of this invention may be respectively called "the base material of this invention" and "the adhesive layer of this invention." In addition, “adhesive tape” shall include the meaning of “adhesive sheet”. That is, the adhesive tape for optics of the present invention may be an adhesive sheet having a sheet-like form.

A second aspect of the present invention provides an image display device in which the optical adhesive tape of the first aspect of the present invention and an image display panel are laminated. The image display device of the second aspect of the present invention may be referred to as “the image display device of the present invention” in this specification.

Additionally, 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 in a row. The tiling display of the third aspect of the present invention may be referred to as “the tiling display of the present invention” in this specification.

Hereinafter, embodiments of the adhesive tape for optics of the present invention will be described with reference to the drawings, but the present invention is not limited thereto and is merely an example.

1 is a schematic diagram showing one embodiment of an optical adhesive tape of the present invention. (a) is a cross-sectional view, and (b) is a top view.

In Fig. 1(a), the optical adhesive tape 10A has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated. The base material 1 has a first face 1a and a second face 1b, and an adhesive layer 2 is laminated on the first face 1a of the base material 1.

In Figure 1(b), the width direction (TD) and machine direction (MD) of the optical adhesive tape 10A are determined to correspond to the width direction (TD) and machine direction (MD) of the substrate 1. You will lose.

In Fig. 2, the optical adhesive tape 10B has a laminated structure in which a base material 1 and an adhesive layer 2 are laminated. The base material 1 has a first face 1a and a second face 1b, and an adhesive layer 2 is laminated on the first face 1a of the base material 1. The second surface 1b of the base material 1 is subjected to anti-reflection treatment and/or anti-glare treatment 3.

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

Fig. 4 is a schematic diagram (perspective view) showing one embodiment of the tiling display of the present invention. In FIG. 4, the tiling display 30 is formed by arranging nine image display devices 20 (stacked structure not shown) in a 3×3 arrangement on a support substrate 31 in a tile shape. and the image display devices 20 are in contact with each other through a gap 32.

Hereinafter, each configuration will be described.

<Optical adhesive tape>

“Optics” in the adhesive tape for optics of the present invention means used for optical purposes, and more specifically, means used for manufacturing products (optical products) using optical members. Examples of optical products include image display devices and input devices such as touch panels, but also include liquid crystal image display devices and self-luminous image display devices (e.g., organic EL (electroluminescence) image display devices). , LED image display devices), etc. In particular, the optical adhesive tape of the present invention is suitable for manufacturing a tiling display in which a plurality of image display devices are arranged in a tile form.

The form of the optical adhesive tape of the present invention is not particularly limited as long as the adhesive layer of the present invention is laminated on the first side of the base material of the present invention. For example, it may be a single-sided adhesive tape in which only one side is an adhesive surface, or it may be a double-sided adhesive tape in which both sides are an adhesive surface. In addition, when the optical adhesive tape of the present invention is a double-sided adhesive tape, both adhesive surfaces of the optical adhesive tape of the present invention may have a form provided by the adhesive layer of the present invention, and one adhesive surface may have a shape provided by the adhesive layer of the present invention. It may be provided by the adhesive layer of the present invention, and the other adhesive surface may be provided by an adhesive layer other than the adhesive layer of the present invention (other adhesive layer). When the optical adhesive tape of the present invention constitutes the outermost surface of an optical product, a single-sided adhesive tape is preferable, and when adherends (optical members) are joined to each other, a double-sided adhesive tape is preferable.

In addition to the base material of the present invention and the adhesive layer of the present invention, the optical adhesive tape of the present invention may include other layers, for example, a base material other than the base material of the present invention, and the adhesive layer of the present invention, to the extent that the effect of the present invention is not impaired. An adhesive layer, intermediate layer, undercoat layer, antistatic layer, separator, surface protection film, etc. other than the layer may be included on the surface or between arbitrary layers.

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

Dimensional change rate (%) = [(Dimension after heating for 500 hours in an environment of 60°C and 90% relative humidity) - (initial dimension)]/(initial dimension) × 100

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

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

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

The configuration of the average dimensional change rate being within ±0.15% suppresses shrinkage or expansion in the tiling display of the present invention under the usage environment of the image display device of the present invention, and makes the gap between the image display devices conspicuous. It is suitable in that it suppresses visible appearance, maintains a good appearance, has little shrinkage or expansion, and maintains transparency without change. In order to prevent the gap between image display devices from being noticeable, to reduce shrinkage or expansion, and to maintain transparency without change, the average dimensional change rate is preferably within ±0.1%, and may be within ±0.05%. do.

Specifically, the average dimensional change rate in the optical adhesive tape of the present invention can be measured by the method of the examples described later. The average dimensional change rate in the optical 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 humidity expansion coefficient and glass transition point of the base material, and the type of resin constituting the adhesive layer of the present invention. , can be adjusted by adjusting the monomer composition, degree of crosslinking, elastic modulus, glass transition point, etc.

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

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

|C×D|≤3

· Maximum curl amount: The laminate is placed on a horizontal surface so that the convex curled surface is at the bottom, and the highest curl amount among the four corners is taken as the maximum curl amount D [mm]. The maximum amount of curl measured with the PET film side of the above-mentioned laminate placed on a horizontal plane facing down is +, and the maximum curl amount measured with the base material side of the above-mentioned laminate placed on a horizontal surface facing down is taken as -.

The configuration in which the absolute value of the product of the average dimensional change rate C [%] and the maximum curl amount D [mm] |C This tiling display is suitable in that it is difficult to visually recognize changes in the gap between the image display devices and the image display devices can be bonded to the film substrate with high precision. Since it is difficult to recognize changes in the gap between the image display devices and the image display device can be bonded to the film substrate with high precision, the |C×D| is preferably 2.5 or less, more preferably 2.4 or less. , may be 2.3 or less, or 2.2 or less.

There is no particular limitation on the lower limit of |C

The absolute value | D From the viewpoint of being able to join, 60 mm or less is preferable, 55 mm or less is more preferable, and 50 mm or less is still more preferable.

The lower limit of |D| is not particularly limited, and the lower the value, the more desirable it is, but may be 0.1 mm or more.

The above |C×D| in the optical adhesive tape of the present invention and |D| can be specifically measured by the method of the examples shown later. The above |C×D| in the optical adhesive tape of the present invention and D It can be adjusted by adjusting the transition point, etc.

The humidity expansion rate of the optical adhesive tape of the present invention when humidified from a relative humidity of 30% at 60°C to a relative humidity of 60% at 60°C is preferably 0.1% or less. The configuration of the humidity expansion rate of 0.1% or less suppresses expansion of the image display device of the present invention due to moisture absorption in the tiling display of the present invention, and suppresses the gap between the image display devices from being noticeable, It is suitable in that there is little 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, reducing shrinkage or expansion, and maintaining transparency without change, the humidity expansion rate is preferably 0.08% or less, and may be 0.06% or less.

The lower limit of the humidity expansion rate is not particularly limited, and the lower the value, the more preferable it is, but may be 0.0001% or more.

Specifically, the humidity expansion coefficient of the optical adhesive tape of the present invention can be measured by the method of the examples described later. The humidity expansion coefficient in the optical adhesive tape of the present invention is the type and thickness of the resin constituting the base material of the present invention, the humidity expansion coefficient and glass transition point of the base material, the type of resin constituting the adhesive layer of the present invention, It can be adjusted by adjusting the monomer composition, degree of crosslinking, elastic modulus, glass transition point, etc.

Ratio of the dimensional change rate in the machine direction to the dimensional change rate in the width direction when the optical adhesive tape of the present invention is heated for 500 hours in an environment of 60°C and 90% relative humidity (dimensional change rate in the machine direction/dimensional change rate in the width direction) is not particularly limited, but 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 in the dimensional change rate 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 gap between the image display devices becomes noticeable. It is suitable in that it suppresses visible appearance, maintains a good appearance, reduces shrinkage or expansion, and maintains transparency without change. The above ratio is preferably 0.6 or more and 1.8 or less, and may be 0.7 or more and 1.5 or less in that the gap between the image display devices is suppressed from being noticeable, shrinkage or expansion is small, and transparency can be maintained without change.

The above ratio (rate of dimensional change in the machine direction/rate of dimensional change in the width direction) in the optical 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 humidity expansion coefficient and glass transition point of the base material, It can be adjusted by adjusting the manufacturing conditions of the base material (for example, the temperature and speed of extrusion molding, etc.), 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, etc.

The haze of the adhesive tape for optics of the present invention is not particularly limited, but is preferably 5% or more. The configuration of the optical adhesive tape of the present invention having a haze of 5% or more can prevent reflection by metal wiring, ITO wiring, etc. disposed 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 image display devices is preferred because it becomes difficult to see, and more preferably it is 6% or more, and may be 7% or more. The upper limit of the haze of the optical adhesive tape of the present invention is not particularly limited, but is preferably 50% or less, and may be 40% or less, or 30% or less, from the viewpoint of visibility of the tiling display of the present invention.

The haze of the optical adhesive tape of the present invention can be measured based on JIS K 7136, and specifically, can be measured by the method described in the examples posted later. The haze of the optical adhesive tape of the present invention is determined by the type and thickness of the resin constituting the substrate of the present invention, the type and thickness of the resin constituting the adhesive layer of the present invention, and the anti-reflection treatment and/or anti-glare treatment on the surface of the substrate. It can be adjusted by carrying out .

The reflectance of the adhesive tape for optics of the present invention is not particularly limited, but is preferably 5% or less. The configuration in which the reflectance of the optical adhesive tape of the present invention is 5% or less can prevent reflection by metal wiring, ITO wiring, etc. disposed 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 image display devices is preferable because it becomes difficult to see, and more preferably it is 3% or less, and may be 1.5% or less. The lower limit of the reflectance of the adhesive tape for optics 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 adhesive tape of the present invention can be measured in accordance with JIS K7361-1, and specifically, can be measured by the method described in the Examples posted later. The reflectance of the optical adhesive tape of the present invention is determined by the type and thickness of the resin constituting the substrate of the present invention, the type and thickness of the resin constituting the adhesive layer of the present invention, and the anti-reflection treatment and/or anti-glare treatment on the surface of the substrate. It can be adjusted by carrying out .

The total light transmittance of the adhesive tape for optics of the present invention is not particularly limited, but is preferably 85% or more. The constitution of the optical adhesive tape of the present invention having a total light transmittance of 85% or more is preferable in that excellent transparency and excellent appearance in the image display device of the present invention are obtained, more preferably 88% or more, and 90% or more. It may be % or more. The upper limit of the total light transmittance of the adhesive tape for optics of the present invention is not particularly limited, but may be 95% or less.

The total light transmittance of the optical adhesive tape of the present invention can be measured based on JIS K7361-1. The total light transmittance of the optical 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 adhesive layer of the present invention, and the anti-reflection treatment and/or anti-glare treatment on the surface of the base material. It can be adjusted by performing processing, etc.

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

<Description>

Materials constituting the base material of the present invention include glass and plastic film. Examples of the plastic film include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and cyclic olefin polymers (COP) (e.g., brand name "Aton" (manufactured by JSR Co., Ltd.) ), brand name “Zeonoa” (manufactured by Nippon Zeon Co., Ltd., etc.), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), triacetylcellulose (TAC), polysulfone, polya Plastic materials such as polyester, polyetheretherketone (PEEK), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer are included. , polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), which have excellent dimensional stability and are difficult to shrink, cyclic olefin polymers (COP), polycarbonate (PC), and polyether ether ketone. (PEEK), transparent polyimide (CPI) are preferred. Additionally, these plastic materials can be used individually or in combination of two or more types. The base material of the present invention is a portion that is attached to the adherend together with the adhesive layer when the optical adhesive tape of the present invention is attached to the adherend (image display panel, etc.). The “base material” does not include a release liner that peels off when the optical 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 side and a second side. The substrate width direction (TD) and machine direction (MD) of the present invention are determined in the manufacturing process of the substrate, and for example, the direction in which the film-shaped extruded body flows after extrusion molding of the raw resin material is the machine direction (MD). , and the width direction (TD) is a 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 a cover member, a polarizing plate, and a retardation plate, and is preferably used as a cover member. When the base material of the present invention is a cover member, the second surface becomes, 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. The configuration in which the substrate glass transition point of the present invention is 60°C or higher is preferable in the tiling display of the present invention because the mechanical properties of the image display device of the present invention are stable under a use environment. From the viewpoint of stability of 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. Additionally, the upper limit of the glass transition point of the substrate is not particularly limited, but from the viewpoint of simplifying the molding process of the substrate, the glass transition point of the substrate is preferably 350°C or lower, 250°C or lower, and 200°C. Hereinafter, it may be 140°C or lower, 130°C or lower, or 125°C or lower.

The glass transition point (Tg) of the base material of the present invention can be measured based on JIS K 7121. The glass transition point (Tg) of the base material of the present invention can be adjusted depending on 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 humidity expansion coefficient of the substrate of the present invention is 5 × 10 ^-5 /%RH or less improves the dimensional stability of the substrate of the present invention when humidity changes, and in the tiling display of the present invention, under the use environment. Suppresses shrinkage or expansion of the image display device of the present invention, prevents gaps between image display devices from becoming noticeable, maintains a good appearance, reduces shrinkage or expansion, and maintains transparency without change. It is suitable for In terms of dimensional stability of the substrate of the present invention, there is little shrinkage or expansion, and transparency can be maintained without change, the humidity expansion coefficient of the substrate of the present invention is preferably 3 × 10 ^-5 /%RH or less, and 2 × It may be 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 value, the more preferable, but may be 0.001 x 10 ^-5 /%RH or more.

The humidity expansion coefficient of the base material of the present invention can be specifically measured by the method described in the examples below. The humidity expansion coefficient of the base material of the present invention can be adjusted depending on the type of resin constituting the base material of the present invention or the conditions (temperature, extrusion speed, etc.) at the time of manufacturing the base material.

The base material haze of the present invention is not particularly limited, but is preferably 5% or more. The configuration in which the base material haze of the present invention is 5% or more can prevent reflection by metal wiring or ITO wiring, etc. disposed on the substrate of the image display panel in the image display device of the present invention. In a tiling display, it is preferable because the gap between image display devices becomes difficult to see, 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 is preferably 50% or less, and may be 40% or less, or 30% or less, from the viewpoint of visibility of the tiling display of the present invention.

The base material haze of the present invention can be measured based on JIS K 7136. The haze 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, applying anti-reflection treatment and/or anti-glare treatment to the surface of the base material, etc.

The reflectance of the base material of the present invention is not particularly limited, but 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 by metal wiring, ITO wiring, etc. disposed on the substrate of the image display panel in the image display device of the present invention, and the present invention In a tiling display, the gap between image display devices is preferred because it becomes difficult to see, and is more preferably 3% or less, and may be 1.5% or less. The lower limit of the reflectance of the substrate of the present invention is not particularly limited, but may be 0.1% or more, or 0.3% or more.

The reflectance of the base material of the present invention can be measured based on 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, applying anti-reflection treatment and/or anti-glare treatment to the surface of the base material, etc.

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

The second surface of the base material of the present invention is preferably subjected to reflective surface treatment and/or anti-glare treatment. The configuration in which the second side of the substrate of the present invention is subjected to reflective surface treatment and/or anti-glare treatment can prevent reflection by metal wiring, ITO wiring, etc. disposed on the substrate of the image display device of the present invention. It is desirable in that it exists. Additionally, in the tiling display of the present invention, it is also preferable in that gaps between image display devices become difficult to be recognized.

As the anti-reflection treatment, any known anti-reflection treatment can be used without particular limitation, and examples include anti-reflection (AR) treatment.

As the anti-reflection (AR) treatment, known AR processing can be applied without particular limitation, and specifically, an optical thin film or the optical thin film whose thickness and refractive index are strictly controlled is applied on the second surface of the substrate of the present invention. This can be carried out by forming an anti-reflection layer (AR layer) of two or more layers. The AR layer exhibits an anti-reflection function by eliminating the reversed phases of incident light and reflected light using the interference effect of light. The wavelength range of visible light that develops the anti-reflection function is, for example, 380 to 780 nm, and the wavelength range with particularly high visibility is in the range of 450 to 650 nm, and the AR layer is designed to minimize the reflectance of 550 nm, which is the central wavelength. It is desirable.

The AR layer generally includes a multilayer anti-reflection layer having a structure in which 2 to 5 optical thin layers (thin films with strictly controlled thickness and refractive index) are laminated, and a plurality of layers of components with different refractive indices are formed to a predetermined thickness. By forming, the degree of freedom in 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. Since high thickness precision is required for the optical thin film, the formation of each layer is generally performed by dry methods such as vacuum evaporation, sputtering, and CVD.

Additionally, the AR layer can also be formed using a coating liquid for forming an anti-reflection layer. The coating liquid for forming the anti-reflection layer may contain, for example, a resin, a fluorine element-containing additive, hollow particles, solid particles, and a diluting solvent, and can be prepared by mixing them, for example.

Examples of the resin include thermosetting resin and ionizing radiation curing resin that cures with ultraviolet rays or light. As the resin, it is also possible to use a commercially available thermosetting resin or ultraviolet curing resin.

As the thermosetting resin or ultraviolet curing resin, for example, a curable compound having at least one of an acrylate group and a methacrylate group that cures by heat, light (ultraviolet rays, etc.) or electron beams can be used, for example Acrylates and methacrylates of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and polyhydric alcohols. Oligomers or prepolymers may be mentioned. These may be used individually as one type, or may be used in combination of two or more types.

For the above resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group can also be used. The reactive diluent may be, for example, a reactive diluent described in Japanese Patent Application Laid-Open No. 2008-88309, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate. Includes etc. As the reactive diluent, acrylate with three or more functions and methacrylate with three or more functions 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 glycerin ether diacrylate, acrylate of isocyanuric acid, and methacrylate of isocyanuric acid. These may be used individually as one type, or may be used in combination of two or more types. 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, and may be 100,000 or less, 70,000 or less, 50,000 or less, 30,000 or less, or 10,000 or less. If the weight average molecular weight before curing is high, hardness decreases, but cracks tend to be less likely to occur when bent. On the other hand, when the weight average molecular weight before curing is low, the crosslinking density between molecules improves and the hardness tends to increase.

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

To cure the curable resin, for example, a curing agent may be added. The curing agent is not particularly limited, and for example, known polymerization initiators (eg, thermal polymerization initiators, photopolymerization initiators, etc.) can be appropriately used. The addition amount of the curing agent is not particularly limited, but is, for example, 0.5 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, with respect to 100 parts by weight of the resin in the coating liquid for forming the anti-reflection layer. Alternatively, it may be 2.5 parts by weight or more, 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less.

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. The organic compound is not particularly limited, but examples include a fluorine-containing antifouling coating agent, a fluorine-containing acrylic compound, and a fluorine- and silicon-containing acrylic compound. Specifically, the organic compound includes, for example, the brand name "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd., and the brand name "Megapac" manufactured by DIC Corporation. The above inorganic compounds are also not particularly limited. The amount of the fluorine element-containing additive added is not particularly limited, but for example, the weight of the fluorine element in the solid content is, for example, 0.05% by weight or more, with respect to the total weight of the solid content in the coating liquid for forming the anti-reflection layer. It may be 0.1 weight% or more, 0.15 weight% or more, 0.20 weight% or more, or 0.25 weight% or more, and may be 20 weight% or less, 15 weight% or less, 10 weight% or less, 5 weight% or less, or 3 weight% or less. In addition, for example, the weight of the fluorine element-containing additive is, for example, 0.05% by weight or more, 0.1% by weight or more, 0.15% by weight or more, or 0.20% by weight, with respect to 100 parts by weight of the resin in the coating solution for forming the anti-reflection layer. It may be % or more or 0.25% by weight or more, and may be 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less.

The hollow particles are not particularly limited, but may be, for example, silica particles, acrylic particles, acrylic-styrene copolymer particles, etc. Examples of the silica particles include "Thrulia 5320" and "Thrulia 4320" manufactured by Nikki Shokubai Kasei Kogyo 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, and may be 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. It's okay. The shape of the hollow particles is not particularly limited. For example, they may be roughly spherical in the form of beads, or may be of an irregular shape such as powder, but are preferably roughly spherical, and more preferably have an aspect ratio of 1.5 or less. It is a spherical particle, and most preferably it is a spherical particle. By adding the hollow particles, for example, a low refractive index and good anti-reflection properties of the anti-reflection layer can be achieved. The addition amount of the hollow particles is not particularly limited, but is, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, or 90 parts by weight or more with respect to 100 parts by weight of the resin in the coating liquid for forming the anti-reflection layer. Alternatively, it may be 100 parts by weight or more, 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less. From the viewpoint of lowering the refractive index of the anti-reflection layer, it is preferable that the amount of the hollow particles added is not too small, and from the viewpoint of securing the mechanical properties of the anti-reflection layer, it is preferable that the amount of the hollow particles added is not too large.

The solid particles are not particularly limited, but may be, for example, silica particles, zirconium oxide particles, or titanium-containing particles (eg, titanium oxide particles). Examples of the silica particles include brand 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. It's okay. The shape of the solid particles is not particularly limited. For example, they may be roughly spherical in the form of beads, or may be of an irregular shape such as powder, but are preferably roughly spherical, and more preferably have an aspect ratio of 1.5 or less. It is a spherical particle, and most preferably it is a spherical particle. By adding the solid particles, for example, the fluorine element-containing additive becomes easy to be distributed on the surface of the coating liquid for forming the anti-reflection layer, and the anti-reflection layer has excellent scratch resistance, low refractive index, and good anti-reflection properties. etc. can be realized. The addition amount of the solid particles is not particularly limited, but is, for example, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more with respect to 100 parts by weight of the resin in the coating solution for forming the antireflection layer. Alternatively, it may be 25 parts by weight or more, 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 diluting solvent may be, for example, a mixed solvent containing MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate). The mixing ratio in this case is not particularly limited, but when the weight of MIBK is 100% by weight, the weight of PMA is, for example, 20% by weight or more, 50% by weight or more, 100% by weight or more, or 150% by weight or more. , or it may be 200% by weight or more, and may be 400% by weight or less, 350% by weight or less, 300% by weight or less, or 250% by weight or less.

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

The addition amount of the diluting solvent is not particularly limited, but for example, the weight of solid content relative to the total weight of the coating liquid for forming an anti-reflection layer is, for example, 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, 1.0% by weight or more. It may be % by weight or more, or 1.5 weight% or more, and may be 20 weight% or less, 15 weight% or less, 10 weight% or less, 5 weight% or less, or 3 weight% or less. From the viewpoint of ensuring coatability (wetting, leveling), it is preferable that the solid content is not too high, and from the viewpoint of preventing appearance defects caused by drying, such as air drying unevenness and whitening, it is preferable that the solid content is not too low. .

Next, the coating liquid for forming an anti-reflection layer is applied onto the second side of the base material of the present invention (the coating step). The coating method is not particularly limited, and 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. . The coating amount of the coating solution for forming the anti-reflection layer is not particularly limited, but the thickness of the anti-reflection layer formed is, for example, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more. It may be as large as possible, and may be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less.

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

Additionally, the coating film may be cured (curing process). The curing can be performed, for example, by heating, light irradiation, etc. The light is not particularly limited, but may be, for example, ultraviolet rays. The light source for the above light irradiation is also not particularly limited, but may be, for example, a high-pressure mercury lamp. The irradiation amount of the energy ray source in the above ultraviolet curing is preferably 50 to 500 mJ/cm 2 as the integrated exposure amount at an ultraviolet ray wavelength of 365 nm. When the irradiation amount is 50 mJ/cm2 or more, curing is likely to proceed sufficiently, and the hardness of the formed anti-reflection layer is likely to increase. In addition, if it is 500 mJ/cm 2 or less, coloring of the formed anti-reflection layer can be prevented.

As the anti-glare (AG) treatment, known AG treatments can be applied without particular restrictions, and can be performed, for example, by forming an anti-glare layer on the second side of the base material of the present invention. As the anti-glare layer, any known layer can be employed without limitation, and is generally formed as a layer in which inorganic or organic particles as an anti-glare agent are dispersed in a resin.

The anti-glare layer is not particularly limited, but is formed using, for example, an anti-glare layer forming material containing a resin, particles, and a thixotropy-imparting agent, and the particles and the thixotropy-imparting agent agglomerate to form the above-described anti-glare layer. A convex portion is formed on the surface of the anti-glare layer. With this configuration, the anti-glare layer has excellent display characteristics that combine anti-glare properties and prevention of white blur, and, despite forming the anti-glare layer using particle aggregation, it has anti-glare properties that cause appearance defects. Product yield can be improved by preventing the generation of protrusions on the surface of the glare layer.

Examples of the resin include thermosetting resin and ionizing radiation curing resin that is cured with ultraviolet rays or light. As the resin, it is also possible to use a commercially available thermosetting resin or ultraviolet curing resin.

As the thermosetting resin or ultraviolet curing resin, for example, a curable compound having at least one of an acrylate group and a methacrylate group that cures by heat, light (ultraviolet rays, etc.) or electron beams can be used, for example Acrylates and methacrylates of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and polyhydric alcohols. Oligomers or prepolymers may be mentioned. These may be used individually as one type, or may be used in combination of two or more types.

For the above resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group can also be used. The reactive diluent may be, for example, a reactive diluent described in Japanese Patent Application Laid-Open No. 2008-88309, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate. Includes etc. As the reactive diluent, acrylate with three or more functions and methacrylate with three or more functions are preferable. This is because the hardness of the anti-glare layer can be made excellent. Examples of the reactive diluent include butanediol glycerin ether diacrylate, acrylate of isocyanuric acid, and methacrylate of isocyanuric acid. These may be used individually as one type, or may be used in combination of two or more types.

The resin preferably contains a urethane acrylate resin, and is more preferably a copolymer of a curable urethane acrylate resin and a multifunctional acrylate (for example, pentatritol triacrylate).

The main function of the particles for forming the anti-glare layer is to provide anti-glare properties by giving the surface of the formed anti-glare layer an uneven shape and to control the haze value of the anti-glare layer. The haze value of the anti-glare layer can be designed by controlling the difference in refractive index between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited and include, for example, silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, zirconium oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin. Particles, calcium sulfate particles, etc. can be mentioned. In addition, the organic particles are not particularly limited and include, for example, polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, and benzogua. Examples include amine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyethylene fluoride resin powder. These inorganic particles and organic particles may be used individually as one type, or may be used in combination of two or more types.

The weight average particle diameter (D) of the particles is preferably within the range of 2.5 to 10 μm. By setting the weight average particle size of the particles within the above range, for example, anti-glare properties can be improved and white clouding can be prevented. The weight average particle diameter of the particles is more preferably in the range of 3 to 7 μm. In addition, the weight average particle diameter of the particles can be measured, for example, by the Coulter count method. For example, using a particle size distribution measuring device using the pore electrical resistance method (product name: Coulter Multisizer, manufactured by Beckman Coulter), the electrical resistance of the electrolyte solution is equivalent to the particle volume when the particles pass through the pores. By measuring, 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. For example, they may be roughly spherical in the form of beads, or may be of an irregular shape such as powder, but are preferably roughly spherical, and more preferably are substantially spherical with an aspect ratio of 1.5 or less. particles, and most preferably are spherical particles.

The ratio of the particles in the anti-glare layer is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, and even more preferably in the range of 1 to 7 parts by weight, based on 100 parts by weight of the resin. This is the range of parts by weight. By setting it within the above range, for example, anti-glare properties can be improved and white fading can be prevented.

The anti-glare layer may contain a thixotropy imparting agent. By including the thixotropy imparting agent, the aggregation state of the particles can be easily controlled. Examples of thixotropy imparting agents for forming the anti-glare layer include organic clay, oxidized polyolefin, and modified urea.

The organic clay is preferably a clay that has been organically treated to improve compatibility with the resin. Examples of organic clay include layered organic clay. 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 (brand names, all Cope Chemicals) (subject); ESBEN, ESBEN C, ESBEN E, ESBEN W, ESBEN P, ESBEN WX, ESBEN N-400, ESBEN NX, ESBEN NX80, ESBEN NO12S, ESBEN NEZ, ESBEN NO12, S Ben NE, Esben NZ, Esben NZ70, Organite, Organite D, Organite T (brand names, all manufactured by Hojun Co., Ltd.); Gunipia F, Gunipia G, Gunipia G4 (brand names, all manufactured by Kunimine High School Co., Ltd.); Thixogel VZ, Creighton HT, Creighton 40 (brand name, all manufactured by Lockwood Additives), etc.

The oxidized polyolefin may be self-prepared or a commercially available product may be used. Examples of the above-mentioned commercial products include Dispalon 4200-20 (brand name, manufactured by Kusumoto Kasei Co., Ltd.), Flonon SA300 (brand name, manufactured by Kyoesha Chemical Co., Ltd.), and the like.

The modified urea is a reaction product of an isocyanate monomer or an adduct thereof and an organic amine. The above-mentioned modified urea may be self-prepared or a commercially available product may be used. Examples of the commercially available products include BYK410 (manufactured by Big Chemistry).

The thixotropy imparting agent may be used individually or in combination of two or more types.

It is preferable that the height of the convex portion from the illuminance average line of the anti-glare layer is less than 0.4 times the thickness of the anti-glare layer. More preferably, it is in the range of 0.01 times to less than 0.4 times, and even more preferably, it is in the range of 0.01 times to less than 0.3 times. Within this range, it is possible to appropriately prevent the formation of projections that cause appearance defects on the convex portion. By having convex portions of this height, the anti-glare layer can make it difficult to generate appearance defects. Here, the height at the average line can be measured, for example, by the method described in Japanese Patent Application Laid-Open No. 2017-138620.

The ratio of the thixotropy imparting agent in the anti-glare 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, based on 100 parts by weight of the resin.

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

The relationship between the thickness (d) of the anti-glare 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 this relationship, an anti-glare layer with excellent anti-glare properties, white fading can be prevented, and no defects in appearance can be obtained.

In the optical adhesive tape of the present invention, as described above, the anti-glare layer forms a convex portion on the surface of the anti-glare layer by agglomerating the particles and the thixotropy imparting agent. In the agglomerated portion forming the convex portion, the particles exist in a state in which a plurality is gathered in the surface direction of the anti-glare layer. As a result, the convex portion has a gentle shape. By having the convex portion of this shape, the anti-glare layer can prevent white fading while maintaining anti-glare properties, and can also make it difficult for appearance defects to occur.

The surface shape of the anti-glare layer can be designed arbitrarily by controlling the aggregation state of particles contained in the anti-glare layer forming material. The aggregation state of the particles can be controlled, for example, by the material of the particles (e.g., chemical modification state of the particle surface, affinity for solvent or resin, etc.), type and combination of resin (binder) or solvent, etc. You can. Here, the aggregation state of the particles can be controlled by the thixotropy imparting agent included in the anti-glare layer forming material. As a result, the agglomeration state of the particles can be made as described above, and the convex portion can be given a gentle shape.

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

Even when applied to the optical adhesive tape of the present invention having such a penetrating layer, a desired gentle surface uneven shape that achieves both anti-glare properties and prevention of white blur can be easily formed. The penetration layer is preferably formed thicker in order to improve adhesion to the substrate with poor adhesion to the anti-glare layer.

In the anti-glare layer, it is preferable that there be no more than one appearance defect per 1 m 2 of the anti-glare layer with a maximum diameter of 200 μm or more. More preferably, it does not have the above-mentioned appearance defects.

In the uneven shape of the surface of the anti-glare layer, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5, and even more preferably in the range of 1.0 to 4.0, It is particularly preferred that it is 1.6 to 4.0. Here, the average inclination angle θa is a value defined by the following equation (1). The average inclination angle θa is a value measured by, for example, the method described in Japanese Patent Application Laid-Open No. 2017-138620.

Average inclination angle θa=tan-1Δa (1)

In the above equation (1), Δa is the peak of the adjacent mountain and the lowest point of the valley in the reference length L of the roughness curve specified in JIS B 0601 (1994 edition), as shown in equation (2) below. It is the sum of the differences (height h) (h1+h2+h3...+hn) divided by the above-mentioned reference length L. The roughness curve is a curve obtained by removing a surface waviness component longer than a predetermined wavelength from a cross-sectional curve using a phase difference compensation high-pass filter. Additionally, the cross-sectional curve is a contour that appears at the cut portion when the target surface is cut in a plane perpendicular to the target surface.

Δa=(h1+h2+h3…+hn)/L (2)

If θa is within the above range, anti-glare properties are excellent and white blur can be prevented.

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

Ti value=β1/β2

Here, β1 is the viscosity measured under the condition of a shear rate of 20 (1/s) using Rheostress 6000 manufactured by HAAKE, and β2 is the viscosity measured under the condition of a shear rate of 200 (1/s) using Rheostress 6000 manufactured by HAAKE. It is viscosity.

If the Ti value is less than 1.3, defects in appearance are likely to occur, and the characteristics regarding anti-glare properties and white clouding deteriorate. Additionally, when the Ti value exceeds 3.5, the particles become difficult to aggregate and tend to be in a dispersed state.

The manufacturing method of the anti-glare layer is not particularly limited and may be manufactured by any method, for example, an anti-glare layer forming material (coating solution) containing the resin, the particles, the thixotropy imparting agent, and the solvent. It can be manufactured by preparing, applying the anti-glare layer forming material (coating liquid) to the second side of the substrate of the present invention to form a coating film, and curing the coating film 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, emboss roll, etc. can also be used.

The solvent is not particularly limited, and various solvents can be used. One type may be used individually, or two or more types may be used in combination. There is an optimal solvent type or solvent ratio depending on the composition of the resin, the type and content of the particles and the thixotropy imparting agent, etc. The solvent is not particularly limited, but examples include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and 2-methoxyethanol; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; Glycols such as ethylene glycol and propylene glycol; Cellosolves such as ethyl cellosolve and butyl cellosolve; Aliphatic hydrocarbons such as hexane, heptane, and octane; Aromatic hydrocarbons such as benzene, toluene, and xylene can be mentioned.

As a base material of the present invention, for example, when a polyester resin is employed to form a permeable layer, a good solvent for the polyester resin can be suitably used. Examples of the solvent include ethyl acetate, methyl ethyl ketone, and cyclopentanone.

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

Various leveling agents can be added to the anti-glare layer forming material. As the leveling agent, for the purpose of preventing coating unevenness (uniforming the coating surface), for example, a fluorine-based or silicon-based leveling agent can be used. A leveling agent can be appropriately selected depending on the case where anti-fouling properties are required on the surface of the anti-glare layer, or when a layer containing an anti-reflection layer (low refractive index layer) or an interlayer filler is formed on the anti-glare layer. For example, by including the thixotropy imparting agent, thixotropic properties can be expressed in the coating solution, so coating unevenness is unlikely to occur. For this reason, it has the advantage of being able to expand the options of the leveling agent, for example.

The blending amount of the leveling agent is, for example, 5 parts by weight or less, preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the resin.

If necessary, pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, anti-fouling agents, antioxidants, etc. may be added to the anti-glare layer forming material to the extent that performance is not impaired. These additives may be used individually, or two or more types may be used together.

For the anti-glare layer forming material, for example, a conventionally known photopolymerization initiator such as that described in Japanese Patent Application Laid-Open No. 2008-88309 can be used.

Methods for coating the anti-glare layer forming material on the second side of the substrate of the present invention include, for example, fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating. Coating methods such as coating can be used.

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

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 ray source is preferably 50 to 500 mJ/cm 2 as the integrated exposure amount at an ultraviolet ray wavelength of 365 nm. If the irradiation amount is 50 mJ/cm2 or more, curing becomes more sufficient and the hardness of the anti-glare layer formed becomes more sufficient. Additionally, if it is 500 mJ/cm2 or less, coloring of the formed anti-glare layer can be prevented.

As described above, the anti-glare layer can be formed on the second surface of the substrate of the present invention. Additionally, the anti-glare layer may be formed by a manufacturing method other than the method described above. The hardness of the anti-glare layer, in terms of pencil hardness, is also affected by the thickness of the layer, but it is preferable to have a hardness of 2H or more.

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

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

In addition, in order to prevent the adhesion of contaminants and improve the ease of removal of the attached contaminants, an anti-contamination layer formed of a silane-based compound containing a fluorine group or an organic compound containing a fluorine group is placed on the anti-reflection layer and/or the anti-glare layer. Lamination is preferred.

It is preferable to perform surface treatment on at least one of the base material of the present invention and the anti-glare layer. When the surface of the substrate of the present invention is surface treated, adhesion to the anti-glare layer is further improved. Additionally, when the surface of the anti-glare layer is surface treated, adhesion to the AR layer is further improved.

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

<Adhesive layer>

The adhesive layer of the present invention may be an adhesive layer without a base material (base layer), or may be a type of adhesive layer with a base material. In addition, in this specification, a pressure-sensitive adhesive layer without a base material (base layer) may be referred to as a “base-free pressure-sensitive adhesive layer,” and a type of pressure-sensitive adhesive layer with a base material may be referred to as a “pressure-sensitive adhesive layer with a base material.” There are cases where it is called. As the inorganic adhesive layer, for example, a single-layer adhesive layer containing only the adhesive layer of the present invention, or an adhesive layer containing the adhesive layer of the present invention and another adhesive layer (an adhesive layer other than the adhesive layer of the present invention) etc. can be mentioned. In addition, the adhesive layer provided with the above substrate includes an adhesive layer having the adhesive layer of the present invention on both sides of the substrate, or an adhesive layer having the adhesive layer of the present invention on one side of the substrate and another adhesive layer on the other side. A pressure-sensitive adhesive layer, etc. can be mentioned. As the “base material (base layer)” constituting the “pressure-sensitive adhesive layer with a base material,” a plastic film similar to the base material of the present invention can be used.

The shear force of the adhesive layer of the present invention (shear force when 1 cm 2 of adhesive area is bonded to a resin plate and stretched in the shear direction at a tensile speed of 0.06 mm/min at 23°C) is 20 N/cm 2 or less. The configuration in which the adhesive layer shear force of the present invention is 20 N/cm2 or less ensures that the adhesive layer of the present invention sufficiently follows the contraction or expansion under the usage environment of the image display device of the present invention and can suppress lifting or peeling. It is desirable in that respect. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. From the point of suppressing the lifting or peeling of the optical adhesive tape of the present invention and being able to follow a level difference, the shear force of the adhesive layer of the present invention is preferably 15 N/cm 2 or less, and may be 13 N/cm 2 or less. The lower limit of the shear force of the adhesive layer of the present invention is not particularly limited, but is 5 N/cm2 or more from the viewpoint of processability, such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention. This is preferable and may be 7 N/cm2 or more.

The shear force of the adhesive layer of the present invention is measured by shear force measurement in the examples described later. The shear force of the adhesive layer of the present invention is determined by the composition of the adhesive composition for forming the adhesive layer of the present invention (e.g., type and molecular weight of base polymer, amount used, monomer composition, type and amount of functional group, type and amount of crosslinking agent) It can be adjusted depending on the curing conditions (heating conditions, radiation conditions), etc.

The glass transition point (Tg) of the adhesive layer of the present invention is preferably -10°C or lower. The configuration in which the pressure-sensitive adhesive layer Tg of the present invention is -10°C or lower maintains the stress relaxation properties of the pressure-sensitive adhesive layer even in a low-temperature environment, and the pressure-sensitive adhesive layer is resistant to shrinkage or expansion under the use environment of the image display device of the present invention. This is desirable because it sufficiently follows the pattern, can suppress lifting and peeling, and can sufficiently secure adhesion to the adherend. From the viewpoint of suppressing lifting and peeling in the image display device of the present invention and providing good adhesion to the adherend, the glass transition point of the adhesive layer of the present invention is preferably -15°C or lower, and may be -20°C or lower. The lower limit of the Tg of the adhesive layer of the present invention is not particularly limited, but is -50° C. or higher from the viewpoint of processability, such as the problem of the adhesive layer protruding from the edge during storage of the optical adhesive tape of the present invention. This is preferable, and may be -40°C or higher.

The glass transition point (Tg) of the pressure-sensitive adhesive layer of the present invention is measured by dynamic viscoelasticity measurement in the examples described later. The glass transition point (Tg) of the adhesive layer of the present invention is determined by determining the composition of the adhesive composition for forming the adhesive layer of the present invention (e.g., type and molecular weight of base polymer, amount used, monomer composition, type and amount of functional group, crosslinker) type and amount) or curing conditions (heating conditions, radiation conditions), etc.

The storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, but is preferably 80 kPa or less. The configuration in which the storage modulus of the adhesive layer of the present invention is 80 kPa or less at 70°C and 1 Hz means that the adhesive layer of the present invention sufficiently follows the contraction or expansion under the usage environment of the image display device of the present invention, and does not float or float. This is preferable because peeling can be suppressed. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. In order to suppress the lifting and peeling of the optical adhesive tape of the present invention and to be able to follow a level difference, the storage modulus of the adhesive layer of the present invention at 70°C and 1 Hz is more preferably 70 kPa or less, or 60 kPa or less. It may be less than 50kPa. The lower limit of the storage elastic modulus at 70°C and 1 Hz of the adhesive layer of the present invention is not particularly limited, but the processability such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention is unlikely to occur. From the viewpoint, 1 kPa or more is preferable, and 5 kPa or more may be sufficient.

The loss tangent at 70°C and 1 Hz of the adhesive layer of the present invention is not particularly limited, but is preferably 0.15 or more. The configuration in which the loss tangent of the adhesive layer of the present invention is 0.15 or more at 70°C and 1 Hz means that the adhesive layer of the present invention sufficiently follows the shrinkage or expansion under the usage environment of the image display device of the present invention, preventing lifting or peeling. It is desirable in that it can suppress. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. In order to suppress lifting and peeling of the optical adhesive tape of the present invention and to be able to follow a level difference, the loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is preferably 0.2 or more, 0.25 or more, or 0.3. It can be more than that. The upper limit of the loss tangent of the adhesive layer of the present invention at 70°C and 1 Hz is not particularly limited, but the processability, such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention, is unlikely to occur. From the viewpoint, 1 or less is preferable and may be 0.8 or less.

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

The 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, but is preferably 10 N/cm2 or less. The configuration in which the 300% tensile residual stress value of the adhesive layer of the present invention is 10 N/cm2 or less ensures that the adhesive layer of the present invention sufficiently follows the contraction or expansion under the usage environment of the image display device of the present invention and does not float or float. This is preferable because peeling can be suppressed. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. In order to suppress the lifting or peeling of the optical adhesive tape of the present invention and to be able to follow the difference in level, the 300% tensile residual stress value of the adhesive layer of the present invention is more preferably 7 N/cm2 or less, and 5 N/cm2 or less. It's okay. The lower limit of the 300% tensile residual stress value of the adhesive layer of the present invention is not particularly limited, but is from the viewpoint of processability, such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention. , 1N/cm2 or more is preferable, and may be 1.5N/cm2 or more.

The 300% tensile residual stress value of the adhesive layer of the present invention is measured by measuring the 300% tensile residual stress value in the examples shown later. The 300% tensile residual stress value of the adhesive layer of the present invention is determined by the composition of the adhesive composition for forming the adhesive layer of the present invention (e.g., type and molecular weight of base polymer, amount used, monomer composition, type and amount of functional group, It can be adjusted by the type and amount of crosslinking agent) or curing conditions (heating conditions, radiation conditions), etc.

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

<Shear test>

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

Restoration rate (%) = (deformation amount A - deformation amount B) / deformation amount A × 100

In this specification, when referring to “strain amount A”, “strain amount B”, and “recovery rate”, unless otherwise specified, “strain amount A”, “strain amount B”, and “recovery rate” obtained in the shear test above are referred to. It should be indicated.

The above “shear test” will be explained with reference to the drawings. Figure 5 is a schematic diagram for explaining the shear test, where 40 indicates an adhesive layer and 41 and 42 indicate parallel plates.

The adhesive layer 40 is a disc-shaped adhesive layer with a thickness of 2 mm and a diameter of 7.9 mm, and is composed of the adhesive layer of the present invention, and the parallel plates 41 and 42 each have a top and bottom surface with a diameter of 7.9 mm. , for example, made of stainless steel, etc. (Figure 5(a)). The top surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are positioned and brought into contact with the bottom surface and top surface of the adhesive layer 40, respectively (FIG. 5(b)). Next, the ambient temperature is set to 60°C, and a shear force F in the twist direction of 500 Pa is applied to the adhesive layer 40 for 600 seconds (FIG. 5(c)). Next, the shear force of the parallel plates 41 and 42 is released, and the shear force is left at 0 Pa for 1800 seconds (Figure 5(d)). “Deformation amount A” is the amount of change in the twist direction at the time (Figure 5(c)) when shear force F was applied for 600 seconds to the outer circumference (100%) of the adhesive layer 40 at the initial stage (Figure 5(b)). It is a percentage (%). “Deformation amount B” is the shear force F applied to the outer circumference (100%) of the adhesive layer 40 at the initial stage ((b) in FIG. 5) for 600 seconds and then left for 1800 seconds at a shear force of 0 Pa (FIG. 5 (b) It is the percentage (%) of the change in the twist direction of d)). The restoration rate (%) is calculated from the following formula.

Restoration rate (%) = (deformation amount A - deformation amount B) / deformation amount A × 100

The configuration in which the recovery rate of the adhesive layer of the present invention is 95% or less allows the adhesive layer to sufficiently follow the contraction or expansion under the usage environment of the image display device of the present invention, and can suppress lifting or peeling, transparency. It is desirable in that it can be maintained without change. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. Since the optical adhesive tape of the present invention can be suppressed from lifting or peeling, transparency can be maintained without change, and can follow steps, the recovery rate of the adhesive layer of the present invention is more preferably 94% or less, and 93.5% or less. It's okay. The lower limit of the recovery rate of the adhesive layer of the present invention is not particularly limited, but is 70% or more from the viewpoint of processability such that problems of the adhesive layer protruding from the ends are unlikely to occur when the optical adhesive tape of the present invention is stored. It is preferable and may be 80% or more, or 85% or more.

The amount of deformation A of the adhesive layer of the present invention is not particularly limited, but is preferably 3% or more. The configuration in which the deformation amount A of the adhesive layer of the present invention is 3% or more is that the adhesive layer sufficiently follows the contraction or expansion under the usage environment of the image display device of the present invention and can suppress lifting or peeling. desirable. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. Since the optical adhesive tape of the present invention can be suppressed from lifting or peeling and can follow a level difference, the amount of deformation A of the adhesive layer of the present invention is more preferably 4% or more, and may be 5% or more. The upper limit of the amount of deformation A of the present invention is not particularly limited, but the transparency can be maintained without change from the viewpoint of processability, such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention. In that sense, 25% or less is preferable, and may be 20% or less, or 15% or less.

The amount of deformation B of the adhesive layer of the present invention is not particularly limited, but is preferably 0.1% or more. The configuration in which the deformation amount B of the adhesive layer of the present invention is 0.1% or more is that the adhesive layer sufficiently follows the contraction or expansion under the usage environment of the image display device of the present invention and can suppress lifting or peeling. desirable. In addition, when the adherend, such as an image display panel, has uneven steps caused by wiring or the like, it is also desirable because the adhesive layer sufficiently follows the steps and can be filled without leaving bubbles or the like. From the point of suppressing the lifting and peeling of the optical adhesive tape of the present invention and being able to follow the level difference, the amount of deformation B of the adhesive layer of the present invention is preferably 0.2% or more, and may be 0.3% or more. The upper limit of the amount of deformation B of the present invention is not particularly limited, but it is possible to maintain the transparency without change from the viewpoint of processability, such as the problem of the adhesive layer protruding from the end during storage of the optical adhesive tape of the present invention. Because of this, 10% or less is preferable, and may be 8% or less, or 5% or less.

Specifically, the amount of deformation A, amount B, and recovery rate of the adhesive layer of the present invention are measured by measuring the amount of deformation A, amount B, and recovery rate in the examples described later. The amount of deformation A, amount of deformation B, and recovery rate of the adhesive layer of the present invention are determined by determining the composition of the adhesive composition for forming the adhesive layer of the present invention (e.g., type and molecular weight of base polymer, amount used, monomer composition, type and amount of functional group) , type and amount of crosslinking agent) or curing conditions (heating conditions, radiation conditions), etc.

The adhesive constituting the adhesive layer of the present invention is not particularly limited, but includes, for example, an acrylic adhesive, a rubber adhesive, a vinyl alkyl ether adhesive, a silicone adhesive, a polyester adhesive, a polyamide adhesive, a urethane adhesive, and a fluorine adhesive. , epoxy-based adhesives, etc. Among them, as the adhesive constituting the adhesive layer, an acrylic adhesive is preferable in terms of transparency, adhesiveness, weather resistance, cost, and ease of designing the adhesive. That is, it is preferable that the adhesive layer of the present invention is an acrylic adhesive layer composed of an acrylic adhesive. The above adhesives can be used individually or in combination of two or more types.

The acrylic 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. Additionally, acrylic polymers can be used individually or in combination of two or more types.

The adhesive composition forming the adhesive layer of the present invention may be in any form. For example, the adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray curing type, or a heat melt type (hot melt type). Among them, solvent-based and active energy ray-curable adhesive compositions are preferred because it is easy to obtain a pressure-sensitive adhesive layer with excellent productivity, optical properties, and appearance. In particular, an active energy ray-curable adhesive composition is preferable from the viewpoint of easy control of the various properties of the adhesive layer (particularly, 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 rays, and electron beams, and ultraviolet rays, and ultraviolet rays are particularly preferable. That is, the active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet ray-curable pressure-sensitive adhesive composition.

As the adhesive composition (acrylic adhesive composition) forming the acrylic adhesive layer, for example, an acrylic adhesive composition containing an acrylic polymer as an essential component, or a mixture of monomers (monomers) constituting the acrylic polymer (referred to as a “monomer mixture”) in some cases) or an acrylic adhesive composition containing the partially polymerized product as an essential ingredient. Examples of the former include so-called solvent-type acrylic adhesive compositions. also. Examples of the latter include so-called active energy ray-curable acrylic adhesive compositions. The above-mentioned “monomer mixture” means a mixture containing the monomer components constituting the polymer. In addition, the above-mentioned “partially polymerized product” may also be referred to as a “prepolymer” and means a composition in which one or two or more monomer components in the monomer mixture are partially polymerized.

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 of (meth)acrylic acid alkyl ester as an essential monomer component. That is, the acrylic polymer preferably contains an alkyl (meth)acrylate ester as a structural unit. In this specification, “(meth)acryl” refers to “acryl” and/or “methacryl” (either or both of “acryl” and “methacryl”), and the same applies to others. Additionally, the acrylic polymer is composed of one or two or more monomer components.

As the above-mentioned (meth)acrylic acid alkyl ester as an essential monomer component, (meth)acrylic acid alkyl ester having a straight-chain or branched alkyl group is preferably used. In addition, (meth)acrylic acid alkyl ester can be used individually or in combination of two or more types.

The (meth)acrylic acid alkyl ester having a straight-chain or branched alkyl group is not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, Heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, (meth)acrylate ) Isodecyl acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, (meth)acrylate Heptadecyl acrylate, octadecyl (meth)acrylate (stearyl (meth)acrylate), isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. with a carbon number of 1 to 20 Examples include (meth)acrylic acid alkyl esters having a straight-chain or branched alkyl group. 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 acrylic acid 2. -Ethylhexyl (2EHA), isostearyl acrylate (ISTA), lauryl acrylate (LA), and butylacrylate (BA). In addition, the (meth)acrylic acid alkyl esters having the above-mentioned linear or branched alkyl groups can be used individually or in combination of two or more types.

The proportion 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). It is preferable, more preferably 53 to 90% by weight, and even more preferably 55 to 85% by weight.

Additionally, the acrylic adhesive composition may contain the alkyl (meth)acrylate ester in addition to the acrylic polymer. When the acrylic adhesive composition contains an alkyl (meth)acrylate in addition to the acrylic polymer, the content (mixing amount) of the alkyl (meth)acrylate is 10 parts by weight or more (e.g., based on 100 parts by weight of the acrylic polymer). For example, it is preferably 10 to 100 parts by weight, more preferably 20 to 90 parts by weight, and even 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. Additionally, copolymerizable monomers can be used individually or in combination of two or more types.

There are no particular limitations on the copolymerizable monomer, but from the viewpoint of easy control of the various properties (especially shear force, glass transition point, etc.) of the pressure-sensitive adhesive layer within a predetermined range, suppression of clouding in a high-humidity environment and improvement of durability, In terms of 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 preferably used. That is, the acrylic polymer preferably contains a monomer having a nitrogen atom in the molecule as a structural unit. Additionally, 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 “monomer containing a nitrogen atom.” The nitrogen atom-containing monomer is not particularly limited, but preferred examples include cyclic nitrogen-containing monomers and (meth)acrylamides. In addition, nitrogen atom-containing monomers can be used individually or in combination of two or more types.

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

Examples of the cyclic nitrogen-containing monomer include N-vinyl cyclic amide (lactam-based vinyl monomer) and a vinyl-based monomer having a nitrogen-containing heterocycle.

Examples of the N-vinyl cyclic amide include N-vinyl cyclic amide represented by the following formula (1).

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

R ¹ in the formula (1) is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (for example, alkylene group, etc.).

Examples of N-vinyl cyclic amides represented by the formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, and N-vinyl-2-pyrrolidone. -2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. are mentioned.

Examples of the vinyl monomer having the nitrogen-containing heterocycle include acrylic monomers having nitrogen-containing heterocycles such as morpholine ring, piperidine ring, pyrrolidine ring, and piperazine ring.

The vinyl monomer having the nitrogen-containing heterocycle is not particularly limited, but examples include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N- Vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrroli Money, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine, etc. are mentioned.

As the vinyl monomer having a nitrogen-containing heterocycle, an acrylic monomer having a nitrogen-containing heterocycle is preferable, and more preferably (meth)acryloylmorpholine, (meth)acryloylpyrrolidine, ( It is meth)acryloylpiperidine.

Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl (meth)acrylamide, and N,N-dialkyl (meth)acrylamide. Examples of the N-alkyl (meth)acrylamide include N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-n-butyl (meth)acrylamide, and N-octyl (meth)acrylamide. etc. can be mentioned. In addition, the N-alkyl (meth)acrylamide includes (meth)acrylamide having an amino group such as dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide. Also included. Examples of the N,N-dialkyl (meth)acrylamide include N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and N,N-dipropyl (meth)acrylamide. Amide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide, etc. there is.

In addition, the above-mentioned (meth)acrylamides also include various N-hydroxyalkyl (meth)acrylamides, for example. Examples of the N-hydroxyalkyl (meth)acrylamide include N-methylol (meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, and N-(2-hydroxypropyl). (meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide , N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-methyl-N-2-hydroxyethyl(meth)acrylamide, etc. You can.

In addition, the above-mentioned (meth)acrylamides also include various N-alkoxyalkyl (meth)acrylamides, for example. Examples of the N-alkoxyalkyl (meth)acrylamide include N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and the like.

In addition, examples of nitrogen atom-containing monomers other than the cyclic nitrogen-containing monomers and (meth)acrylamides include amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, and isocyanate group-containing monomers. Examples of the 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 (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.) and itaconimide-based monomers. Monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N -lauryl itaconimide, N-cyclohexyl itaconimide, etc.), succinimide monomers (e.g., N-(meth)acryloyloxymethylene succinimide, N-(meth)acrylo 1-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide, etc.) can be mentioned. Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate.

Among them, as the nitrogen atom-containing monomer, cyclic nitrogen-containing monomer is preferable, and N-vinyl cyclic amide is more preferable. 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 not particularly limited. However, 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 clouding and durability in a high-humidity environment are further improved, and high adhesion reliability can be obtained, so it is preferable. In addition, the upper limit of the ratio of the nitrogen atom-containing monomer is determined by obtaining a pressure-sensitive adhesive layer with appropriate flexibility, obtaining a pressure-sensitive adhesive layer with excellent transparency, and various characteristics of the pressure-sensitive adhesive layer (especially shear force, glass transition point, etc.). From the viewpoint of easy control to a predetermined range, 30% by weight or less is preferable, more preferably 25% by weight or less, and even more preferably 20% by weight or less.

The monomer having a hydroxyl group within the molecule is a monomer having at least one hydroxyl group (hydroxyl group) within the molecule (within one molecule) and a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or vinyl group. and those having a hydroxyl group are preferably mentioned. 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, hydroxyl group-containing monomers can be used individually or in combination of two 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 groups such as 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl) (meth)acrylate. Contains (meth)acrylic acid ester; vinyl alcohol; Allyl alcohol, etc. can be mentioned.

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

When the acrylic polymer contains the hydroxyl-containing monomer as a monomer component constituting the polymer, the proportion of the hydroxyl-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited. , from the viewpoint of suppressing clouding in a high-humidity environment, improving durability, and obtaining high adhesive reliability, it is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, and even more preferably 1% by weight or more. In addition, the upper limit of the ratio of the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 30% by weight or less, from the viewpoint of easy control of the various properties (especially shear force, glass transition point, etc.) of the pressure-sensitive adhesive layer within a predetermined range. It is preferably 25% by weight or less, and more preferably 20% by weight or less.

In addition, for the purpose of further enhancing the effect of the hydroxyl-containing monomer, the acrylic adhesive composition may contain a hydroxyl-containing monomer in addition to the acrylic polymer. When the acrylic pressure-sensitive adhesive composition contains a hydroxyl-containing monomer in addition to the acrylic polymer, the content (mixing amount) of the hydroxyl-containing monomer is preferably 1 part by weight or more, more preferably 3 parts by weight, based on 100 parts by weight of the acrylic polymer. It is at least 5 parts by weight, and more preferably at least 5 parts by weight. When the above content is 5 parts by weight or more, suppression of clouding and durability in a high-humidity environment are further improved, and higher adhesion reliability can be obtained, so it is preferable. In addition, the upper limit of the content (mixing amount) of the hydroxyl group-containing monomer is determined by predetermined values for cohesion, adhesiveness, ease of obtaining adhesive reliability, and the various characteristics of the adhesive layer (especially shear force, glass transition point, etc.). From the viewpoint of easy control, 30 parts by weight or less is preferable, more preferably 25 parts by weight or less, further preferably 20 parts by weight or less, and particularly preferably 17 parts by weight or less.

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 can be used to suppress whitening in a high-humidity environment, improve durability, and From the viewpoint of obtaining adhesion reliability, it 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 sum of the above ratios is to obtain a pressure-sensitive adhesive layer with appropriate flexibility, to obtain a pressure-sensitive adhesive layer with excellent transparency, and to maintain the various characteristics of the pressure-sensitive adhesive layer (especially shear force, glass transition point, etc.) within a predetermined range. From the viewpoint of easy control, it 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 also 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 also has an alicyclic structure. For example, alkyl (meth)acrylate having a cycloalkyl group is included in the alicyclic structure-containing monomer. In addition, the alicyclic structure-containing monomer can be used individually or in combination of two 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 especially preferably 6 to 10 carbon atoms. do.

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, dicyclofentanyl (meth)acrylate, HPMPA represented by formula (2) below, TMA-2 represented by formula (3) below, formula below (meth)acrylic monomers such as HCPA represented by (4) can be mentioned. In addition, in the following formula (4), the bonding site between the cyclohexyl ring connected by a line and the structural formula in parentheses is not particularly limited. Among these, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferable.

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. However, from the viewpoint of improving durability and obtaining high adhesive reliability, it is preferable that it is 10% by weight or more. In addition, the upper limit of the ratio of the alicyclic structure-containing monomer is from the viewpoint of obtaining a pressure-sensitive adhesive layer with appropriate flexibility and from the viewpoint of making it easy to control the various properties of the pressure-sensitive adhesive layer (especially shear force, glass transition point, etc.) to a predetermined range. , 50% by weight or less is preferable, more preferably 40% by weight or less, and even more preferably 30% by weight or less.

In addition, examples of copolymerizable monomers include polyfunctional monomers. Examples of the multifunctional 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, etc. In addition, polyfunctional monomers can be used individually or in combination of two 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 not particularly limited. , from the viewpoint of easy control of the above-described various properties of the adhesive layer (especially shear force, glass transition point, etc.) to a predetermined range, 0.5% by weight or less (for example, exceeding 0% by weight and less than or equal to 0.5% by weight). It is preferable, and more preferably, it is 0.2% by weight or less (for example, exceeding 0% by weight and not more than 0.2% by weight).

Additionally, the multifunctional monomer may be blended into the acrylic adhesive composition in addition to the acrylic polymer. When the acrylic pressure-sensitive adhesive composition contains a polyfunctional monomer in addition to the acrylic polymer, the content (mixing amount) of the polyfunctional monomer is determined by the above-described various properties of the pressure-sensitive adhesive layer (in particular, shear force and glass), based on 100 parts by weight of the acrylic polymer. From the viewpoint of easy control of the transition point, etc.) within a predetermined range, the amount is preferably 0.5 parts by weight or less (e.g., more than 0 part by weight and less than or equal to 0.5 parts by weight), and more preferably 0.2 parts by weight or less (e.g., , exceeding 0 parts by weight and less than or equal to 0.2 parts by weight).

Additionally, examples of the copolymerizable monomer include (meth)acrylic acid alkoxyalkyl ester. 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, ( Examples include 3-methoxypropyl (meth)acrylic acid, 3-ethoxypropyl (meth)acrylic acid, 4-methoxybutyl (meth)acrylic acid, and 4-ethoxybutyl (meth)acrylic acid. Among them, the (meth)acrylic acid alkoxyalkyl ester is preferably acrylic acid alkoxyalkyl ester, and more preferably 2-methoxyethyl acrylate (MEA). In addition, the above-mentioned (meth)acrylic acid alkoxyalkyl esters can be used individually or in combination of two or more types.

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 to the (meth)acrylic acid alkoxyalkyl ester is not particularly limited. However, the [former:latter] (weight ratio) is preferably greater than 100:0 and 25:75 or less, and more preferably greater 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, (meth)acrylic acid esters having an aromatic hydrocarbon group, vinyl esters, aromatic vinyl compounds, olefins, or Dienes, vinyl ethers, vinyl chloride, etc. can be mentioned. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and examples of the carboxyl group-containing monomer include maleic anhydride and anhydride. Monomers containing acid anhydride groups such as itaconic acid are also included. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and the like. Examples of the sulfonic acid group-containing monomer include sodium vinyl sulfonate. Examples of the phosphoric acid group-containing monomer include 2-hydroxyethyl acryloyl phosphate. Examples of the (meth)acrylic acid ester having the 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, vinyl toluene, and the like. 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 adhesive layer with 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, and in particular does not contain a carboxyl group-containing monomer. It is preferable that it does not contain or substantially does not contain it. Examples of acidic group-containing monomers include carboxyl group-containing monomers, sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers. Specifically, the proportion of acidic group-containing monomers 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). You can.

The content of the base polymer (especially acrylic polymer) in the adhesive layer of the present invention is not particularly limited, but is 50% by weight or more (for example, 50 to 100% by weight) based on 100% by weight of the total weight of the adhesive layer of the present invention. %) is preferable, more preferably 80% by weight or more (for example, 80 to 100% by weight), and even more preferably 90% by weight or more (for example, 90 to 100% by weight).

The weight average molecular weight (Mw) of the acrylic polymer is 100,000 to 5,000,000, preferably 500,000 to 4,000,000, and more preferably 750,000 to 3,000,000. A configuration in which the weight average molecular weight of the acrylic polymer is 100,000 or more is preferable because the adhesive strength is improved and the foaming and peeling resistance is improved. 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 because it is easy to increase the adhesive force and improves foaming and peeling resistance.

The weight average molecular weight (Mw) of the acrylic polymer can be calculated in terms of polystyrene by GPC method. For example, it can be measured under the following conditions using a high-speed GPC device "HPLC-8120GPC" manufactured by Tosoh Corporation.

Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000

Solvent: Tetrahydrofuran

Flow rate: 0.6ml/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, and even more preferably -60 to -20°C. . It is preferable that the glass transition temperature of the acrylic polymer is -70°C or higher because the cohesion is improved and the foaming and peeling resistance is easily improved. In addition, the configuration in which the glass transition temperature of the acrylic polymer is -10°C or lower maintains the stress relaxation property of the adhesive layer even in a low temperature environment, and prevents shrinkage or expansion under the use environment of the image display device of the present invention. This is preferable because the adhesive layer follows sufficiently, can suppress lifting and peeling, and can sufficiently secure adhesion to the adherend.

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

1/Tg=W ₁ /Tg ₁ +W ₂ /Tg ₂ +… + _Wn / _Tgn

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

As the homopolymer Tg of the monomer constituting the acrylic polymer, the following value can be adopted.

2-Ethylhexyl acrylate -70℃

n-hexyl acrylate -65℃

n-octylacrylate -65℃

Isononyl acrylate -60℃

n-nonyl acrylate -58℃

n-butylacrylate -55℃

Ethyl acrylate -20℃

Lauryl acrylate 0℃

2-Ethylhexyl methacrylate -10℃

Methyl acrylate 8℃

n-butyl methacrylate 20℃

Methyl methacrylate 105℃

Acrylic acid 106℃

Methacrylic acid 228℃

Vinyl acetate 32℃

Styrene 100℃

Additionally, as the homopolymer Tg of monomers not described above, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc, 1989) can be adopted. In addition, as the homopolymer Tg of a monomer that is not described in the above literature, the value obtained by the measurement method described above (peak top temperature of tan δ by viscoelasticity test) can be adopted.

Base polymers such as the acrylic polymers contained in the adhesive layer of the present invention are obtained by polymerizing monomer components. This 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 by irradiating active energy rays (active energy ray polymerization method). Among them, from the viewpoint of transparency of the adhesive layer, cost, etc., the solution polymerization method and the active energy ray polymerization method are preferable, and the active energy ray polymerization method is more preferable.

In addition, when polymerizing the above monomer component, various general solvents may be used. 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; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone can be mentioned. In addition, solvents can be used individually or in combination of two or more types.

When polymerizing the above monomer component, a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) may be used, depending on the type of polymerization reaction. In addition, the polymerization initiator can be used individually or in combination of two or more types.

The thermal polymerization initiator is not particularly limited, but includes, for example, an azo-based polymerization initiator, peroxide-based polymerization initiator (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), redox-based polymerization initiator, etc. I can hear it. Among them, the azo-based polymerization initiator disclosed in Japanese Patent Application Laid-Open No. 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 referred to as "AMBN") 」), 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, etc. Additionally, the thermal polymerization initiator can be used individually or in combination of two or more types.

When using the azo-based polymerization initiator when polymerizing the acrylic polymer, the amount of the azo-based polymerization initiator used is not particularly limited, but for example, relative to 100 parts by weight of all monomer components constituting the acrylic polymer, It is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and also preferably 0.5 parts by weight or less, and more preferably 0.3 parts by weight or less.

The photopolymerization initiator is not particularly limited, but examples include benzoin ether-based photopolymerization initiator, acetophenone-based photopolymerization initiator, α-ketol-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, and benzoate. A phosphorus-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. In addition, acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators can be mentioned. 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, etc. are mentioned. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloroacetophenone, etc. can be mentioned. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, etc. You can. Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime-based 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 and the like. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the ketal-based photopolymerization initiator include benzyldimethyl ketal. Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and 2,4-dioxanthone. Isopropyl thioxanthone, dodecyl thioxanthone, etc. can be mentioned. Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. . Examples of the titanocene-based photopolymerization initiator include bis(η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)- Phenyl) titanium, etc. may be mentioned. In addition, the photopolymerization initiator can be used individually or in combination of two or more types.

When using the photopolymerization initiator when polymerizing the acrylic polymer, the amount of the photopolymerization initiator used is not particularly limited, but is, for example, 0.01 parts by weight or more based on 100 parts by weight of all monomer components constituting the acrylic polymer. It is preferable, more preferably 0.1 part by weight or more, further preferably 3 parts by weight or less, and more preferably 1.5 parts by weight or less.

The acrylic adhesive composition preferably contains an acrylic oligomer having a weight average molecular weight of 1,000 to 30,000 together with the acrylic polymer. Containing an acrylic oligomer improves the adhesion to the adherend at the interface of the optical adhesive tape of the present invention, making it easy to obtain strong adhesion and excellent anti-foaming peeling properties. In addition, in this specification, “acrylic oligomers having a weight average molecular weight of 1,000 to 30,000” may simply be referred to as “acrylic oligomers.”

The acrylic oligomer preferably includes an acrylic polymer composed of (meth)acrylic acid ester having a cyclic structure in the molecule as an essential monomer component, and (meth)acrylic acid ester having a cyclic structure in the molecule and a straight-chain or branched alkyl group. A more preferable example is an acrylic polymer composed of an alkyl (meth)acrylate ester as an essential monomer component. That is, the acrylic oligomer preferably includes an acrylic polymer containing (meth)acrylic acid ester having a cyclic structure in the molecule as a monomer unit, and (meth)acrylic acid ester having a cyclic structure in the molecule as a monomer unit and a straight-chain or A more preferable example is an acrylic polymer containing an alkyl (meth)acrylate ester having a branched alkyl group.

The cyclic structure (ring) of the (meth)acrylic acid ester (hereinafter sometimes referred to as “ring-containing (meth)acrylic acid ester”) having a cyclic structure within the molecule (within 1 molecule) is an aromatic ring or a non-aromatic ring. It may be of any gender and is not particularly limited. Examples of the aromatic ring include aromatic carbocycles (for example, monocyclic carbocycles such as benzene rings, condensed carbocycles such as naphthalene rings, etc.), and various aromatic heterocycles. Examples of the non-aromatic ring include non-aromatic aliphatic rings (non-aromatic alicyclic rings) [for example, cycloalkane rings such as cyclopentane ring, cyclohexane ring, cycloheptane ring, and cyclooctane ring; cycloalkene rings such as cyclohexene rings, etc.], non-aromatic cross-linked rings [e.g., bicyclic hydrocarbon rings such as pinane, pinene, bornane, norbornane, norbornene, etc.; aliphatic hydrocarbon rings (cross-linked hydrocarbon rings) of three or more rings in adamantane, etc.], non-aromatic heterocycles (for example, epoxy rings, oxolane rings, oxetane rings, etc.), etc.

Examples of the aliphatic hydrocarbon ring having three or more rings (crosslinked hydrocarbon ring having three or more rings) include, for example, a dicyclopentanyl group represented by the following formula (5a), a dicyclopentenyl group represented by the following formula (5b), and the following formula ( Examples include an adamantyl group represented by 5c), a tricyclopentanyl group represented by the following formula (5d), and a tricyclopentenyl group represented by the following formula (5e).

That is, examples of the ring-containing (meth)acrylic acid ester include cycloalkyl (meth)acrylate such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. ester; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; Dicyclofentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclofentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl ( (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings, such as meth)acrylate and 2-ethyl-2-adamantyl (meth)acrylate; Aromatics such as (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, (meth)acrylic acid aryloxyalkyl esters such as phenoxyethyl (meth)acrylate, and (meth)acrylic acid arylalkyl esters such as benzyl (meth)acrylate. and (meth)acrylic acid ester having a ring. Among them, as the ring-containing (meth)acrylic acid ester, non-aromatic ring-containing (meth)acrylic acid ester is particularly preferable, and more preferably cyclohexyl acrylate (CHA), cyclohexyl methacrylate (CHMA), and acrylic acid disi. Clofentanyl (DCPA) and dicyclofentanyl methacrylate (DCPMA), and more preferably dicyclofentanyl acrylate (DCPA) and dicyclofentanyl methacrylate (DCPMA). In addition, ring-containing (meth)acrylic acid ester may be used individually or in combination of two or more types.

Among the non-aromatic ring-containing (meth)acrylic acid esters, the use of (meth)acrylic acid ester having an aliphatic hydrocarbon ring of three or more rings (especially a bridged hydrocarbon ring of three or more rings) is particularly preferable because it is less likely to cause polymerization inhibition. do. In addition, (meth)acrylic acid ester having a dicyclofentanyl group represented by the formula (5a), an adamantyl group represented by the formula (5c), and a tricyclofentanyl group represented by the formula (5d) without an unsaturated bond. When used, foaming and peeling resistance can be further improved, and adhesion to low-polar adherends such as polyethylene or polypropylene can be significantly improved.

The content (ratio) of the ring-containing (meth)acrylic acid ester in the total monomer units of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but the total amount of monomer components constituting the acrylic oligomer (100 Parts by weight), 10 to 90 parts by weight is preferable, and more preferably 20 to 80 parts by weight. If the content of the ring-containing (meth)acrylic acid ester is 10 parts by weight or more, the foaming and peeling resistance is likely to improve, so it is preferable. In addition, if the content is 90 parts by weight or less, the adhesive layer has appropriate flexibility, and adhesive strength, step absorption, etc. are likely to be improved, so it is preferable.

In addition, as the (meth)acrylic acid alkyl ester having the above-mentioned linear or branched alkyl group as a monomer unit of the acrylic oligomer, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylic acid. Isopropyl, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate , heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, ( Isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, (meth)acrylate ) (meth)acrylic acid alkyl esters where the alkyl group has 1 to 20 carbon atoms, such as heptadecyl acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among them, methyl methacrylate (MMA) is preferable because it has good compatibility with acrylic polymers. In addition, the above-mentioned (meth)acrylic acid alkyl esters may be used individually or in combination of two or more types.

The content (ratio) of the (meth)acrylic acid alkyl ester having the above-mentioned straight-chain or branched alkyl group in the total monomer units of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but foaming-resistant peeling In terms of performance, the amount 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, based on the total amount (100 parts by weight) of the monomer component constituting the acrylic oligomer. When the content is 10 parts by weight or more, the adhesion to the adherend made of acrylic resin or polycarbonate is likely to be improved, and is therefore preferable.

The monomer unit of the acrylic oligomer may include, in addition to the above-mentioned ring-containing (meth)acrylic acid ester and (meth)acrylic acid alkyl ester having a straight-chain or branched alkyl group, a monomer (copolymerizable monomer) that can be copolymerized with these monomers. . In addition, the content (ratio) of the above-mentioned copolymerizable monomer in the total monomer units of the acrylic oligomer (the total amount of monomer components constituting the acrylic oligomer) is not particularly limited, but the total amount of monomer components constituting the acrylic oligomer (100 parts by weight) ), it is preferably 49.9 parts by weight or less (for example, 0 to 49.9 parts by weight), and more preferably 30 parts by weight or less. In addition, the copolymerizable monomer may be used individually or in combination of two or more types.

Examples of the copolymerizable monomer (the copolymerizable monomer constituting the acrylic oligomer) as a monomer unit of the acrylic oligomer include (meth)acrylic acid alkoxyalkyl ester [e.g., (meth)acrylic acid 2-methoxyethyl, (meth)acrylic acid. ) 2-ethoxyethyl acrylate, (meth)acrylic acid methoxytriethylene glycol, (meth)acrylic acid 3-methoxypropyl, (meth)acrylic acid 3-ethoxypropyl, (meth)acrylic acid 4-methoxybutyl, (meth)acrylic acid ) 4-ethoxybutyl acrylic acid, etc.]; Hydroxyl group (hydroxyl group)-containing monomers [e.g., 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 3-hydroxy (meth)acrylic acid hydroxyalkyl (meth)acrylates such as oxypropyl, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, vinyl alcohol, allyl alcohol, etc.]; Amide group-containing monomers [e.g., (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-part Toxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, etc.]; Amino group-containing monomers [for example, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, etc.]; cyano group-containing monomers [eg, acrylonitrile, methacrylonitrile, etc.]; Monomers containing sulfonic acid groups (for example, sodium vinylsulfonate, etc.); phosphoric acid group-containing monomers [for example, 2-hydroxyethyl acryloyl phosphate, etc.]; Isocyanate group-containing monomers (for example, 2-methacryloyloxyethyl isocyanate, etc.), imide group-containing monomers (cyclohexyl maleimide, isopropyl maleimide, etc.), etc. can be mentioned.

As described above, the acrylic oligomer is preferably an acrylic polymer containing, as monomer units, (meth)acrylic acid ester having a cyclic structure in the molecule and (meth)acrylic acid alkyl ester having a straight or branched alkyl group. Among them, an acrylic polymer containing a ring-containing (meth)acrylic acid ester and an alkyl (meth)acrylic acid ester having a linear or branched alkyl group as described above is preferable as the monomer unit. In the acrylic polymer containing ring-containing (meth)acrylic acid ester and (meth)acrylic acid alkyl ester having a straight-chain or branched alkyl group as the above monomer units, the total amount of monomer components constituting the acrylic oligomer (100 parts by weight) The amount of 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. In addition, the content of the (meth)acrylic acid alkyl ester having a straight-chain 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 20 parts by weight. It is 60 parts by weight.

In addition, as a particularly preferable specific composition of the acrylic oligomer, as a monomer unit, (1) at least one monomer selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate, and ( 2) An acrylic polymer containing methyl methacrylate can be mentioned. In the acrylic oligomer having the above-mentioned particularly preferred specific structure, the content of (1) dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate (two or more types) in all monomer units of the acrylic oligomer (if included, the total amount thereof) is preferably 30 to 70 parts by weight, (2) the content of methyl methacrylate is preferably 30 to 70 parts by weight, based on the total amount (100 parts by weight) of monomer components constituting the acrylic oligomer. do. However, the acrylic oligomer is not limited to the above specific structure.

The acrylic oligomer can be obtained by polymerizing the above monomer component using a known or common polymerization method. Examples of the polymerization method of 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.

When polymerizing an acrylic oligomer, various general solvents may be used. 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; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone can be mentioned. In addition, these solvents may be used individually or in combination of two or more types.

In addition, when polymerizing an acrylic oligomer, a known or customary polymerization initiator (for example, a thermal polymerization initiator, a photopolymerization initiator, etc.) may be used. In addition, the polymerization initiator may be used individually or in combination of two or more types.

As a thermal polymerization initiator, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis(2 -methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azo Azo-based products such as bis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis(2,4,4-trimethylpentane) initiator; Benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butyl peroxy)-3,3,5- and peroxide-based initiators such as trimethylcyclohexane and 1,1-bis(t-butylperoxy)cyclododecane. Additionally, when performing solution polymerization, it is preferable to use an oil-soluble polymerization initiator. In addition, the thermal polymerization initiator may be used individually or in combination of two or more types.

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

The photopolymerization initiator is not particularly limited, but examples include the same photopolymerization initiator as the photopolymerization initiator used in the polymerization of the acrylic polymer mentioned above. The amount of the photopolymerization initiator used is not particularly limited and is selected appropriately.

When polymerizing the acrylic oligomer, a chain transfer agent may be used to adjust the molecular weight (specifically, to adjust the weight average molecular weight to 1,000 to 30,000). Examples of the 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 thioglycolic acid, ethyl thioglycolic acid, propyl thioglycolic acid, butyl thioglycolic acid, t-butyl thioglycolic acid, 2-ethylhexyl thioglycolic acid, Octyl thioglycolic acid, isooctyl thioglycolic acid, decyl thioglycolic acid, dodecyl thioglycolic acid, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, thioglycolic acid ester of pentaerythritol, α-methyl Styrene dimer, etc. can be mentioned. Among them, from the viewpoint of suppressing whitening of the optical adhesive tape of the present invention due to humidification, α-thioglycerol and methyl thioglycolate are preferable, and α-thioglycerol is particularly preferable. In addition, chain transfer agents may be used individually or in combination of two or more types.

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

The weight average molecular weight (Mw) of the acrylic oligomer is 1000 to 30000, preferably 1000 to 20000, more preferably 1500 to 10000, and even more preferably 2000 to 8000. Since the weight average molecular weight of the acrylic oligomer is 1000 or more, the adhesive force and holding properties are improved, and the foaming and peeling resistance is improved. On the other hand, since the weight average molecular weight of the acrylic oligomer is 30,000 or less, it is easy to increase the adhesive force and improve the foaming and peeling resistance.

The weight average molecular weight (Mw) of the acrylic oligomer can be calculated in terms of polystyrene by GPC method. For example, it can be measured under the following conditions using a high-speed GPC device "HPLC-8120GPC" manufactured by Tosoh Corporation.

Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000

Solvent: Tetrahydrofuran

Flow rate: 0.6ml/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, and still more preferably 40 to 300°C. If the glass transition temperature of the acrylic oligomer is 20°C or higher, the foaming and peeling resistance tends to improve, so it is preferable. Additionally, if the glass transition temperature of the acrylic oligomer is 300°C or lower, the adhesive layer has appropriate flexibility, it is easy to obtain good adhesive strength and good step absorption, and it is easy to obtain excellent adhesive reliability, so it is preferable.

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

As the homopolymer Tg of the monomer constituting the acrylic oligomer, the values shown in Table 1 below can be adopted. Additionally, as the homopolymer Tg of monomers not listed in Table 1, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc, 1989) can be adopted. In addition, as the homopolymer Tg of a monomer that is not described in the above literature, the value obtained by the measurement method described above (peak top temperature of tan δ by viscoelasticity test) can be adopted.

In addition, the copolymer of "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 adhesive composition contains an acrylic polymer and an acrylic oligomer, the content of the acrylic oligomer is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the acrylic polymer. It is 20 parts by weight, more preferably 2 to 10 parts by weight. That is, the content of the acrylic oligomer in the 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 all monomer units of the acrylic polymer. and more preferably 2 to 10 parts by weight. The content of the acrylic oligomer in the acrylic adhesive composition is not particularly limited, but for example, is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, based on 100 parts by weight of the monomer mixture. More preferably, it is 2 to 10 parts by weight. When the content of the acrylic oligomer is 1 part by weight or more, excellent adhesiveness and excellent anti-foaming peeling properties are easily obtained, so it is preferable. Furthermore, if the content of the acrylic oligomer is 30 parts by weight or less, excellent transparency and adhesion reliability are easily obtained, so it is preferable. In addition, from the viewpoint of easy control of the various properties of the adhesive layer (especially shear force, glass transition point, etc.) within a predetermined range, the content of the acrylic oligomer is preferably 10 parts by weight or less, and more preferably 8 parts by weight or less. do.

There is no particular limitation on the method for producing the pressure-sensitive adhesive composition containing an acrylic polymer and an acrylic oligomer. For example, acrylic oligomers, additives, etc. may be added to a mixture of monomer components constituting an acrylic polymer or a partial polymerization of a mixture of monomer components constituting an acrylic polymer (monomer mixture forming an acrylic polymer or a partial polymer thereof) as necessary. It is produced by adding and mixing.

The adhesive layer of the present invention is not particularly limited, but preferably contains an ultraviolet absorber (UVA). It is preferable that the adhesive layer of the present invention contains an ultraviolet absorber because damage to the image display panel due to ultraviolet rays can be suppressed. In addition, ultraviolet absorbers can be used individually or in combination of two or more types.

The ultraviolet absorber is not particularly limited, but examples include benzotriazole-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and oxybenzo. Phenone-based ultraviolet absorbers, etc. can be mentioned.

Examples of benzotriazole-based ultraviolet absorbers (benzotriazole-based compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (brand name “TINUVIN PS”, manufactured by BASF), and benzenepropane. An ester compound of acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 branched and straight chain alkyl) (product 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 -[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2yl)phenyl]propionate mixture (trade name “TINUVIN 109”, manufactured by BASF), 2-( 2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (brand name “TINUVIN 900”, manufactured by BASF), 2-(2H-benzotriazol-2-yl )-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (brand name “TINUVIN 928”, manufactured by BASF), methyl 3-(3-(2H) -benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 reaction product (trade name “TINUVIN 1130”, manufactured by BASF), 2-(2H-benzotria) Zol-2-yl)-p-cresol (brand name “TINUVIN P”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl) Phenol (brand name “TINUVIN 234”, manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (brand name “TINUVIN 326”, BASF) manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (brand name “TINUVIN 328”, manufactured by BASF), 2-(2H-benzotriazol-2-yl) )-4-(1,1,3,3-tetramethylbutyl)phenol (brand name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl) -4-(1,1,3,3-tetramethylbutyl)phenol] (brand name “TINUVIN 360”, manufactured by BASF), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert -Butyl-4-hydroxyphenyl) Reaction product of propionate and polyethylene glycol 300 (trade name “TINUVIN 213”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4 -Methylphenol (brand name “TINUVIN 571”, manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole ( Product name "Sumisorb 250", manufactured by Sumitomo Chemical Co., Ltd., 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (product name "Adeka Step" LA-31", manufactured by ADEKA Co., Ltd.), etc. can be mentioned.

Examples of the hydroxyphenyltriazine-based ultraviolet absorber (hydroxyphenyltriazine-based compound) include 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl) -5-Hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy) methyl] oxirane reaction product (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-dihyde Reaction product of oxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (trade name “TINUVIN 405”, manufactured by BASF) ), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name “TINUVIN 460”, manufactured by BASF) , 2-(4,6-diphenyl-1,3,5-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 (brand name “Adekastab LA-46”, ( (made by ADEKA Co., Ltd.), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine ( Product name "TINUVIN 479", manufactured by BASF Corporation), etc. are mentioned. In addition, a compound represented by the following formula (6) (brand name “TINUVIN 477”, manufactured by BASF) can be mentioned.

Examples of benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone-based compounds) include 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzo. Phenone, 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 (brand name "KEMISORB 111", manufactured by Chemipro Kasei Co., Ltd.), 2,2',4,4 '-Tetrahydroxybenzophenone (brand name "SEESORB 106", manufactured by Cipro Chemical Co., Ltd.), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, etc.

Examples of salicylic acid ester-based ultraviolet absorbers (salicylic acid ester-based compounds) include phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, and phenyl 2-acryloyloxy-4-. Methylbenzoate, phenyl2-acryloyloxy-5-methylbenzoate, phenyl2-acryloyloxy-3-methoxybenzoate, phenyl2-hydroxybenzoate, phenyl2-hydroxy-3-methyl Benzoate, phenyl2-hydroxy-4-methylbenzoate, phenyl2-hydroxy-5-methylbenzoate, phenyl2-hydroxy-3-methoxybenzoate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (brand name "TINUVIN 120", manufactured by BASF), etc.

Cyanoacrylate-based ultraviolet absorbers (cyanoacrylate-based compounds) include, for example, alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, and alkenyl 2-cyanoacrylate. Cyanoacrylate, alkynyl 2-cyanoacrylate, etc. can be mentioned.

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

In addition, the ultraviolet absorber preferably has an absorbance A of 0.5 or less, as determined below, from the viewpoint of obtaining higher ultraviolet absorbing properties and further improving corrosion resistance (particularly UV resistance).

Absorbance A: Absorbance measured by irradiating light with a wavelength of 400 nm to a 0.08% toluene solution of the above ultraviolet absorber.

When the adhesive layer of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber in the adhesive layer of the present invention (especially an acrylic adhesive layer) is not particularly limited, but corrosion resistance (particularly UV resistance) is further improved. From this point of view, it is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more, based on 100 parts by weight of the base polymer. In addition, the upper limit of the content of the ultraviolet absorber is 100 parts by weight of the base polymer in order to suppress the yellowing phenomenon of the adhesive accompanying the addition of the ultraviolet absorber and to obtain excellent optical properties, high transparency, and excellent appearance properties. Relative to this, it is preferably 10 parts by weight or less, more preferably 9 parts by weight or less, and even more preferably 8 parts by weight or less.

The adhesive layer of the present 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 ray absorber. Since the light stabilizer can capture radicals generated from photo-oxidation, it can improve the resistance of the adhesive layer to light (especially ultraviolet rays). Additionally, light stabilizers can be used individually or in combination of two or more types.

The light stabilizer is not particularly limited, but examples include phenolic light stabilizers (phenol-based compounds), phosphorus-based light stabilizers (phosphorus-based compounds), thioether-based light stabilizers (thioether-based compounds), and amine-based light stabilizers (amines). type compounds) (particularly hindered amine type stabilizers (hindered amine type compounds)), etc. are mentioned.

Examples of the phenol-based light stabilizer (phenol-based 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 butylphenol), 4,4'-methylenebis(2,6-di-tertiary butylphenol), 4,4'-butylidene bis(6 -tertiary butyl-m-cresol), 4,4'-thiobis (6-tertiary butyl-m-cresol), styrenated phenol, N,N'-hexamethylenebis (3,5-di- Tertiary butyl-4-hydroxyhydrocinamide, bis(3,5-di-tertiary butyl-4-hydroxybenzylphosphonate ethyl ester) calcium, 1,1,3-tris(2-methyl- 4-hydroxy-5-tertiary butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tertiary butyl-4-hydroxybenzyl)benzene, Tetrakis[3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionyloxymethyl]methane, 1,6-hexanediol-bis[3-(3,5-di-tertiary) Quaternary butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis[6-(1-methylcyclohexyl) -p-cresol], 1,3,5-tris(4-tertiary butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 1,3,5-tris(3,5- di-tertiary butyl-4-hydroxybenzyl)isocyanuric acid, triethylene glycol-bis[3-(3-tertiary butyl-4-hydroxy-5-methylphenyl)propionate], 2, 2'-oxamide bis[ethyl 3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionate], 6-(4-hydroxy-3,5-di-tertiary) Butylanilino)-2,4-dioctylthio-1,3,5-triazine, bis[2-tertiary butyl-4-methyl-6-(2-hydroxy-3-tertiary butyl- 5-methylbenzyl)phenyl]terephthalate, 3,9-bis{2-[3-(3-tertiary butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-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, etc.

Examples of the phosphorus-based light stabilizer (phosphorus-based compound) include trisnonylphenyl phosphite, tris(2,4-di-tertiary butylphenyl)phosphite, and tris[2-tertiary butyl-4-(3- Tertiary butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenylphosphite, di(tridecyl)pentaerythite Ritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tertiary 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 Spite, tetra(tridecyl)-4,4'-n-butylidenebis(2-tertiary butyl-5-methylphenol)diphosphite, hexa(tridecyl)-1,1,3-tris(2 -methyl-4-hydroxy-5-tertiary butylphenyl)butanetriphosphite, tetrakis(2,4-di-tertiary butylphenyl)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)amine, etc. can be mentioned.

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

As the amine-based light stabilizer (amine-based compound), for example, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name “TINUVIN 622”, manufactured by BASF) ), 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 , One-to-one reaction product of 10-diamine (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 (brand 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-piperi Diyl} imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl)imino} (brand name “TINUVIN 944”, manufactured by BASF), bis (1,2,2,6, A mixture of 6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate (trade name “TINUVIN 765”, manufactured by BASF), bis( 2,2,6,6-tetramethyl-4-piperidyl)sebacate (brand name “TINUVIN 770”, manufactured by BASF), decane bisate (2,2,6,6-tetramethyl-1-(octyloxy) )-4-piperidinyl) ester, reaction product of 1,1-dimethylethylhydroperoxide 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- peroxide. Reaction product of butyl 2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol (product name: TINUVIN 152", manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl1,2,2,6,6-pentamethyl-4-piperi A mixture of dilsebacate (trade name “TINUVIN 292”, manufactured by BASF), 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and 3, Mixed ester of 9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (trade name “Adekastab LA-63P”, Co., Ltd. )made by ADEKA), etc. can be mentioned. As the amine-based stabilizer, a hindered amine-based stabilizer is particularly preferable.

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 is in the sense that it facilitates the development of resistance to light. , it is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, based on 100 parts by weight of the base polymer. In addition, the upper limit of the above content is preferably 5 parts by weight or less per 100 parts by weight of the base polymer from the viewpoint of making it difficult to cause coloring due to the light stabilizer itself, making it easy to obtain high transparency, and in terms of optical properties. Preferably it is 3 parts by weight or less.

Although there is no particular limitation on forming the adhesive layer of the present invention, a crosslinking agent may be used. For example, the acrylic polymer in the acrylic adhesive layer can be crosslinked and the gel fraction can be controlled. In addition, the crosslinking agent can be used individually or in combination of two or more types.

The crosslinking agent is not particularly limited, but includes, for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, a peroxide crosslinking agent, a urea crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate crosslinking agent, a metal salt crosslinking agent, and carbodiimide. Examples include cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. Among them, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferable, and isocyanate-based crosslinking agents are more preferable.

Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; Alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. In addition, as the isocyanate-based crosslinking agent, for example, trimethylolpropane/tolylene diisocyanate adduct (trade name “Coronate L”, manufactured by Nippon Polyurethane Kogyo Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (trade name) Commercially available products such as “Coronate HL”, manufactured by Nippon Polyurethane Kogyo Co., Ltd., and trimethylolpropane/xylylene diisocyanate adduct (brand name “Takenate D-110N”, manufactured by Mitsui Chemicals Co., Ltd.) can also be mentioned. there is.

Examples of the epoxy-based crosslinking agent (multifunctional epoxy compound) include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N -diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol Diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether. Cydyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcindi In addition to glycidyl ether and bisphenol-S-diglycidyl ether, epoxy resins having two or more epoxy groups in the molecule can be mentioned. In addition, examples of the epoxy-based crosslinking agent include commercially available products such as “Tetrad C” (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

When a crosslinking agent is used to form the pressure-sensitive adhesive layer of the present invention, the amount of the crosslinking agent used is not particularly limited, but is preferably 0.001 parts by weight or more based on 100 parts by weight of the base polymer from the viewpoint of obtaining sufficient adhesive reliability. Preferably it is 0.01 parts by weight or more. In addition, the upper limit of the above usage amount is from the viewpoint of obtaining appropriate flexibility in the adhesive layer and improving adhesive strength, and from the viewpoint of making it easy to control the various properties of the adhesive layer (especially shear force, glass transition point, etc.) to a predetermined range. , it is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, based on 100 parts by weight of the base polymer.

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

The silane coupling agent is not particularly limited, but examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl- Aminopropyltrimethoxysilane, etc. can be mentioned. Additionally, examples of the silane coupling agent include commercially available products such as brand name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). Among them, γ-glycidoxypropyltrimethoxysilane is preferable as the silane coupling agent.

When the adhesive layer of the present invention contains a silane coupling agent, the content of the silane coupling agent in the adhesive layer of the present invention (particularly, an acrylic adhesive layer) is not particularly limited, but is about 100 parts by weight of the base polymer. , It is preferable that it is 0.01 part by weight or more, and more preferably, it is 0.02 part by weight or more. Additionally, the upper limit of the content of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.5 part by weight or less, based on 100 parts by weight of the base polymer.

The adhesive layer of the present invention may contain an antistatic agent. Additionally, antistatic agents can be used individually or in combination of two or more types. If the adhesive layer contains an antistatic agent, damage to adherends such as image display panels can be prevented.

Examples of the antistatic agents include quaternary ammonium salts, pyridinium salts, cationic antistatic agents having cationic functional groups such as primary, secondary, and tertiary amino groups, sulfonates, sulfuric acid esters, phosphonates, and phosphoric acid esters. anionic antistatic agents having an anionic functional group, alkyl betaine and its derivatives, imidazoline and its derivatives, amphoteric antistatic agents such as alanine and its derivatives, amino alcohol and its derivatives, glycerin and its derivatives, polyethylene glycol and its derivatives. Nonionic antistatic agents such as derivatives, and furthermore, ionic conductive polymers obtained by polymerizing or copolymerizing monomers having the above-mentioned cationic, anionic, or zwitterionic ionic conductive groups.

When the adhesive layer of the present invention contains an antistatic agent, the content of the antistatic agent in the adhesive layer of the present invention is not particularly limited, but is preferably 0.01 part by weight or more with respect to 100 parts by weight of the base polymer, More preferably, it is 0.02 parts by weight or more. Additionally, the upper limit of the content of the antistatic agent is preferably 1 part by weight or less, more preferably 0.5 part by weight or less, based on 100 parts by weight of the base polymer.

The adhesive layer of the present invention may contain a colorant. Additionally, the colorant can be used individually or in combination of two or more types. It is preferable that the adhesive layer contains a colorant because reflection by metal wiring, ITO wiring, etc. disposed on the substrate of the image display device of the present invention can be prevented.

The colorant may be a dye or a pigment as long as it can be dissolved or dispersed in the adhesive layer of the present invention. Dye is preferable because low haze can be achieved even with a small amount of addition, and it is easy to distribute uniformly without settling like a pigment. In addition, pigments are also preferable because color expression is high even when added in a small amount. When using a pigment as a colorant, it is preferable that it has low or no electrical conductivity. In addition, when using dye, it is preferable to use it together with the above-mentioned light stabilizer.

The colorant may be used without limitation as long as it absorbs visible light (wavelength 400 to 700 nm), is transparent to ultraviolet rays (wavelength 330 to 400 nm), or absorbs ultraviolet rays. , It is also desirable to have ultraviolet ray transparency. That is, the colorant is preferably a colorant whose maximum transmittance at a wavelength of 330 to 400 nm is larger than the maximum transmittance at a wavelength of 400 to 700 nm. In addition, the colorant preferably has an average transmittance of 330 to 400 nm with a wavelength greater than that of the coloring agent with a wavelength of 400 to 700 nm. The transmittance of the colorant is diluted with an appropriate solvent or dispersion medium (organic solvent with low absorption in the wavelength range of 330 to 700 nm) such as tetrahydrofuran (THF) so that the transmittance at a wavelength of 400 nm is approximately 50 to 60%. Measurements are made using solutions or dispersions.

Carbon black and titanium black, which are commonly used as black colorants, absorb ultraviolet rays more than they absorb visible light (their ultraviolet ray transmittance is smaller than the visible light transmittance). Therefore, when a colorant such as carbon black is added to an active energy ray-curable acrylic adhesive composition, many of the ultraviolet rays irradiated for photocuring are absorbed by the colorant, the amount of light absorbed by the photopolymerization initiator is small, and photocuring takes time. (the accumulated amount of irradiated light increases). In addition, when the thickness of the adhesive layer is large, there is a tendency for photocuring to become insufficient even if light irradiation is performed for a long period of time because there is little ultraviolet rays reaching the surface opposite to the light irradiation surface. In contrast, by using a colorant that has a higher transmittance of ultraviolet rays compared to visible light, curing inhibition due to the colorant can be suppressed.

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

The content of the colorant in the adhesive layer of the present invention is, for example, about 0.01 to 20 parts by weight based on 100 parts by weight of the base polymer, and is appropriately set depending on the type of colorant, the color tone and light transmittance of the adhesive layer, etc. do. The colorant may be added to the composition as a solution or dispersion dissolved or dispersed in an appropriate solvent.

The adhesive layer of the present invention may further contain a crosslinking accelerator, tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), anti-aging agent, filler, antioxidant, chain transfer agent, plasticizer, softener, and interface as necessary. Additives such as activators may be contained within a range that does not impair the effect of the present invention. In addition, these additives can be used individually or in combination of two or more types.

The haze of the adhesive layer of the present invention is not particularly limited, but is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less from the viewpoint of appearance characteristics, transparency, and optical properties. . In addition, in this specification, the haze of the adhesive layer can be measured according to JIS K 7136, for example, using a haze meter.

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

The thickness of the adhesive layer of the present invention is not particularly limited, but is preferably 12 μm or more, preferably 15 μm or more, more preferably 20 μm or more, especially preferably 70 μm or more, from the viewpoint of obtaining sufficient adhesive reliability. It is more than ㎛. The thickness of 12 μm or more is preferable because the adhesive layer can sufficiently follow the contraction or expansion under the usage environment of the image display device of the present invention and can suppress lifting or peeling. Additionally, from the viewpoint of optical properties, the thickness is preferably 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less.

<Manufacture of optical adhesive tape>

The adhesive tape for optics of the present invention can be prepared by laminating the adhesive layer of the present invention on the first side of the base material of the present invention.

The method of laminating the pressure-sensitive adhesive layer of the present invention on the first side of the substrate of the present invention is not particularly limited. For example, the pressure-sensitive adhesive composition is applied (coated) on a separator, and the obtained pressure-sensitive adhesive composition layer is dried and cured. Alternatively, the pressure-sensitive adhesive composition is applied (coated) on a separator, the resulting pressure-sensitive adhesive composition layer is cured by irradiating active energy rays, thereby forming a sheet-like pressure-sensitive adhesive layer on the separator, and the adhesive composition layer is formed on the first side of the base material of the present invention. This can be done by bonding the adhesive layer to the. Additionally, if necessary, it may be further heated and dried.

When curing by irradiation of active energy rays, a separator is placed on the surface of the coating film, and the adhesive composition is supported between two separators while irradiating active energy rays to prevent polymerization inhibition by oxygen. It is desirable.

Another method of laminating the pressure-sensitive adhesive layer of the present invention on the first side of the base material of the present invention is, for example, applying (coating) the above-described pressure-sensitive adhesive composition onto the first side of the base material of the present invention, and applying the obtained pressure-sensitive adhesive composition layer. Dry curing may be performed, or the adhesive composition may be applied (coated) on the first side of the base material of the present invention, and the obtained adhesive composition layer may be cured by irradiating active energy rays. Additionally, if necessary, it may be further heated and dried.

When curing is performed by irradiation of active energy rays, a separator is laid on the surface of the coating film, and the adhesive composition is irradiated with active energy rays while sandwiched and supported between the base material of the present invention and the separator to prevent polymerization inhibition by oxygen. It is desirable to do so.

Before irradiation with active energy rays, the sheet-like coating film may be heated for the purpose of removing the solvent, etc. When removing solvents, etc. by heating, it is preferable to carry out the removal before laying the separator.

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

The adhesive composition can be produced by known or common methods. For example, a solvent-type acrylic adhesive composition can be produced by mixing additives (for example, ultraviolet absorbers, etc.) into a solution containing the acrylic polymer as needed. For example, an active energy ray-curable acrylic pressure-sensitive adhesive composition can be produced by mixing additives (for example, ultraviolet absorbers, etc.) with the mixture of the above-described acrylic monomers or a partial polymerization thereof, if necessary.

Additionally, a known coating method may be used to apply the adhesive composition. For example, coaters such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, and direct coater may be used.

In particular, when forming a pressure-sensitive adhesive layer using an active energy ray-curable pressure-sensitive adhesive composition, it is preferable that the active energy ray-curable pressure-sensitive adhesive composition contains a photopolymerization initiator. In addition, when the active energy ray-curable adhesive composition contains an ultraviolet absorber, it is preferable to include at least a photopolymerization initiator having light absorption characteristics in a wide wavelength range as the photopolymerization initiator. For example, it is preferable to include at least a photopolymerization initiator that has light absorption properties not only in ultraviolet light but also in visible light. This is because there is a concern that curing by active energy rays may be inhibited by the action of the ultraviolet absorber, and it is easy to obtain high photocurability in the adhesive composition if it contains a photopolymerization initiator with light absorption characteristics in a wide wavelength range.

<Anti-static layer>

The optical adhesive tape of the present invention may have an antistatic layer on the surface or between arbitrary layers. Because the optical 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 conductive coating liquid containing a conductive polymer on a separator. Specifically, it is an antistatic layer formed by coating, for example, a conductive coating liquid containing a conductive polymer on the first side of the base material of the present invention. Specific coating methods include roll coating, bar coating, and gravure coating.

Examples of the conductive polymer include a conductive polymer in which a π-conjugated conductive polymer is doped with a polyanion. Examples of the π-conjugated conductive polymer include chain-shaped conductive polymers such as polythiophene, polypyrrole, polyaniline, and polyacetylene. Examples of polyanions include polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyethyl sulfonic acid, and polymethacryl carboxylic acid.

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

<Separator>

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

As the separator, common release papers, etc. can be used. Specifically, for example, in addition to a base material 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-adhesion substrate containing a non-polar polymer (e.g., 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 side of the separator base material can be suitably used. Examples of such separator substrates include polyester films (polyethylene terephthalate films, etc.), olefin resin films (polyethylene films, polypropylene films, etc.), polyvinyl chloride films, polyimide films, polyamide films (nylon films), and rayon films. In addition to plastic base films (synthetic resin films) and papers (fine paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top coated paper, etc.), these are multi-layered (2 to 3 layers) by lamination or co-extrusion, etc. complex), etc.

The peeling agent constituting the peeling layer is not particularly limited, but for example, a silicone-based peeling agent, a fluorine-based peeling agent, a long-chain alkyl-based peeling agent, etc. can be used. The peeling treatment agent can be used individually or in combination of two or more types.

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

The separator may have an antistatic layer formed on at least one side of the separator base material to prevent damage to adherends such as image display panels. The antistatic layer may be formed on one side of the separator (the peeled surface or the untreated side), or may be formed on both sides of the separator (the peeled surface and the untreated side).

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

As the conductive polymer, one similar to the conductive polymer constituting the antistatic layer constituting the optical adhesive tape of the present invention can be used.

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

<Surface protection film>

In the optical adhesive tape of the present invention, the second surface of the base material of the present invention may be protected by a surface protection film. The surface protection film is used as a protective material for the second side of the base material of the present invention during production or transportation of the optical adhesive tape of the present invention, the image display device of the present invention, or the tiling display of the present invention.

As forming materials for the surface protection film, ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, and polycarbonate resins. , their copolymer resins, etc. Preferably, it is an ester-based resin (especially polyethylene terephthalate-based resin).

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

The surface protection film is bonded in a peelable manner to the second side of the substrate of the present invention via any suitable adhesive. Preferably, a surface protection film with an adhesive layer is formed, and this is bonded to the second side of the base material of the present invention of the optical adhesive tape of the present invention. The adhesive used for lamination of the surface protection film includes, for example, an acrylic resin, a styrene resin, a silicone resin, etc. as a base resin, and a crosslinking agent selected from isocyanate compounds, epoxy compounds, aziridine compounds, etc. to this base resin. Furthermore, an adhesive composition containing a silane coupling agent or the like can be mentioned. The thickness of the adhesive layer is usually 1 μm to 60 μm, preferably 3 μm to 30 μm. If the adhesive layer is too thin, there is a risk that problems such as lowered adhesiveness and air bubbles become more likely to occur, and if it is too thick, there is a risk that problems such as the adhesive protruding out may occur. From the viewpoint of chemical resistance, adhesion, etc., an acrylic adhesive is preferably used.

<Image display device>

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

Since the image display device of the present invention has the optical adhesive tape of the present invention in a laminated structure, shrinkage or expansion under a use environment can be suppressed, and transparency can be maintained without change. Additionally, the pressure-sensitive adhesive layer of the present invention sufficiently follows the contraction or expansion of the image display device, so that lifting or peeling is unlikely to occur. Additionally, when the image display panel has uneven steps due to wiring or the like, the adhesive layer of the present invention sufficiently follows the steps and can be filled without leaving bubbles or the like.

The image display panel is not particularly limited, and includes, for example, a liquid crystal image display panel, a self-luminous image display panel (e.g., an organic EL (electroluminescence) image display panel, an LED image display panel), etc. I can hear it.

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

The image display device of the present invention may be provided with optical members other than the optical adhesive tape of the present invention and the image display panel on the surface or between arbitrary layers. The optical member is not particularly limited, but includes a polarizing plate, a retardation plate, an anti-reflection film, a viewing angle adjustment film, and an optical compensation film. In addition, the optical member shall also include members (design film, decorative film, surface protection plate, etc.) that play a role of decoration or protection while maintaining visibility of the image display device or input device.

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

Specifically, the attachment of the image display panel and the optical adhesive tape of the present invention can be performed by laminating them under heating and/or pressure. After laminating under heating and/or pressure, curing may be performed by irradiating active energy rays. Irradiation of active energy rays can be performed similarly to the formation of the adhesive layer of the present invention.

<Tiling display>

The tiling display of the present invention is formed by arranging a plurality of image display devices of the present invention. In FIG. 4, the tiling display 30 is formed by arranging nine image display devices 20 (stacked structure not shown) in a 3×3 arrangement on a support substrate 31 in a tile shape. and the image display devices 20 are in contact with each other at the gap 32. As the support substrate, a glass plate or plastic film similar to 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, gaps or overlaps are unlikely to occur between a plurality of image display devices in the tiling display of the present invention, and gaps are less likely to be noticeable. It is difficult and a good appearance is maintained. Additionally, there is little shrinkage or expansion, and transparency can be maintained without change. Additionally, the adhesive layer of the present invention sufficiently follows the contraction or expansion of the image display device and can prevent problems caused by lifting or peeling.

Additionally, in the tiling display of the present invention, when anti-reflection treatment and/or anti-glare treatment is applied to the second side of the substrate of the present invention, the metal wiring or ITO disposed on the substrate of the image display device of the present invention This is desirable because it can prevent reflection due to wiring, etc. Additionally, in a tiling display, it is also preferable in that gaps between the image display devices of the present invention become difficult to be recognized.

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

The tiling display of the present invention can be manufactured by arranging a plurality of sheets of the image display device of the present invention on the support substrate without gaps and fixing the outermost surface by sealing with glass or the like.

Example

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

Manufacturing Example 1

(Preparation of anti-glare film 1)

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

The resin contained in the anti-glare layer forming material contains 40 parts by weight of ultraviolet curable urethane acrylate resin (manufactured by Shinnakamura Chemical Company, brand name "NK Oligo UA-53H-80BK") and pentaerythritol triacrylate as main components. 57.5 parts by weight of functional acrylate (manufactured by Osaka Yuki Chemical Co., Ltd., brand name "Viscott #300") and a diluent of a composition for an optical adjustment layer containing zirconia particles and ultraviolet curable resin ("Obster Z7540", JSR 2.5 parts by weight of silicon particles (made by Momentive Performance Materials Japan Godo Kaisha, brand name “Tospearl 130ND”), 2.8 parts by weight of synthetic smectite, an organic clay as a thixotropy imparting agent (Kunimine High School Gabbu) 2.5 parts by weight of Shiki Kaisha, brand name “Smekuton SAN”), 3 parts by weight of a photopolymerization initiator (manufactured by BASF, brand name “OMNIRAD907”), and fine particles of cross-linked acrylic styrene copolymer resin (product name “SSX-, manufactured by Sekisui Chemical Industries, Ltd.) 6.5 parts by weight of “103DXE”) and 0.1 part by weight of leveling agent (manufactured by Kyoesha Chemical Co., Ltd., brand name “LE-303”) were mixed. In addition, the organic clay was diluted with toluene so that the solid content was 6% by weight. This mixture was diluted with a toluene/cyclopentanone (CPN) mixed solvent (weight ratio 64/36) so that the solid concentration was 38% by weight, and an anti-glare layer forming material (coating liquid) was prepared using an ultrasonic disperser. .

[Formation of anti-glare layer 1]

As a substrate, a transparent plastic film substrate (PET film, Toray Co., Ltd. product name “38U413”, thickness: 38 μm) was prepared. The anti-glare layer forming material (coating solution) was applied to one side of the transparent plastic film substrate using a wire bar to form a coating film (coating process). Subsequently, the coating film was dried by heating at 95°C for 1 minute (drying process). Afterwards, ultraviolet rays with a cumulative amount of 300 mJ/cm2 were irradiated with a high-pressure mercury lamp, and the coating film was cured to form an anti-glare layer with a thickness of 6.5 μm. In this way, a laminate of the light-transmitting substrate and the anti-glare layer 1 was obtained.

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

100 parts by weight of a multifunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by Osaka Yuki Chemical Industries, Ltd., brand name "Viscott #300"), and hollow nanosilica particles (Nikki Shokubai Kasei Industries, Ltd.) 100 parts by weight of solid nanosilica particles (manufactured by Nissan Chemical Industries, Ltd., brand name "MIBK-ST", solid content 30% by weight, weight average particle diameter 10nm), 100 parts by weight, , 12 parts by weight of a fluorine element-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., brand name “KY-1203”), 5 parts by weight of a photopolymerization initiator (manufactured by BASF, brand name “OMNIRAD907”), and a photopolymerization initiator (manufactured by BASF). , brand name “OMNIRAD2959”) were mixed. To this mixture, a mixed solvent of MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) in a 70:30 weight ratio was added as a diluting solvent, so that the total solid content was 1.5% by weight, and stirred. A coating liquid for forming an antireflection layer was prepared.

[Formation of anti-reflection layer 1]

The coating liquid for forming an anti-reflection layer was applied to the anti-glare layer surface of the laminate of the light-transmitting substrate and the anti-glare layer 1 using a wire bar (coating process). The above-described coating liquid was heated at 80°C for 1 minute and dried to form a coating film (drying process). The dried coating film was cured by irradiating ultraviolet rays with an accumulated light amount of 300 mJ/cm2 using a high-pressure mercury lamp (curing process). As a result, the coating film was cured to form an anti-reflection layer 1 with a thickness of 0.1 μm (anti-reflection layer forming step). As described above, anti-glare film 1 of this Production Example 1 was manufactured.

Production example 2

(Preparation of anti-glare film 2)

[Formation of anti-glare layer 2]

In the preparation of a coating solution for forming an anti-glare layer, the blending amount of the polyfunctional acrylate containing pentaerythritol triacrylate as a main component was changed to 60 parts by weight, the blending amount of silicon particles was changed to 0.9 parts by weight, and thixotropy Production Example 1, except that 1.5 parts by weight of synthetic smectite, an organic clay, was changed as an imparting agent, a diluent of the composition for an optical adjustment layer containing zirconia particles and an ultraviolet curable resin, and fine particles of a crosslinked acrylic styrene copolymer resin were not used. A laminate of the light-transmitting substrate and anti-glare layer 2 was manufactured in the same manner as above.

[Formation of anti-reflection layer 2]

In preparing the coating solution for forming an anti-reflection layer, anti-reflection layer 2 was formed in the same manner as in Production Example 1, except that the mixing amount of the hollow nano-silica particles was changed to 240 parts by weight. As described above, anti-glare film 2 of Production Example 2 was manufactured.

Production example 3

(Preparation of anti-glare film 3)

In the formation of the anti-glare layer, this production example was carried out in the same manner as production example 1, except that a transparent plastic film substrate (COP film, manufactured by Nippon Zeon Co., Ltd., brand name “ZF14”, thickness: 50 μm) was used as the substrate. Anti-glare film 3 of 3 was prepared.

Production example 4

(Preparation of anti-glare film 4)

In the formation of the anti-glare layer, this production example was carried out in the same manner as production example 1, except that a transparent plastic film substrate (PEN film, manufactured by Toyobo Co., Ltd., brand name “Q51”, thickness: 25 μm) was used as the substrate. Anti-glare film 4 of 4 was prepared.

Production example 5

(Preparation of anti-glare film 5)

In the formation of the anti-glare layer, this production example was carried out in the same manner as production example 1, except that a transparent plastic film substrate (PEEK film, manufactured by Kurabo Co., Ltd., brand name “EXPEEK”, thickness: 50 μm) was used as the substrate. Anti-glare film 5 of 5 was prepared.

Production example 6

(Manufacture of transparent plastic film substrate)

For 81.98 parts by mass of isosorbide (hereinafter sometimes abbreviated as “ISB”), 47.19 parts by mass of tricyclodecane dimethanol (hereinafter sometimes abbreviated as “TCDDM”), diphenyl carbonate (hereinafter as “TCDDM”) 175.1 parts by mass and 0.979 parts by mass of a 0.2 mass% aqueous solution of cesium carbonate as a catalyst are charged into a reaction vessel, and in a nitrogen atmosphere, as the first step of the reaction, the heating tank temperature is set to 150°C. While heating and stirring as necessary, the raw materials were dissolved (about 15 minutes). Next, the pressure was set to 13.3 kPa from normal pressure, and the heating tank temperature was raised to 190°C for 1 hour, while the generated phenol was discharged outside the reaction vessel. After maintaining the entire reaction vessel at 190°C for 15 minutes, as a second stage process, the pressure inside the reaction vessel is set to 6.67 kPa, the heating bath temperature is raised to 230°C for 15 minutes, and the generated phenol is transferred to the reaction vessel. It was released outside. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and in order to remove the generated phenol, the pressure in the reaction vessel was brought to 0.200 kPa or less. After reaching a predetermined stirring torque, the reaction was terminated, and the resulting reaction product was extruded into water to obtain polycarbonate resin pellets. After vacuum drying the obtained polycarbonate resin at 80°C for 5 hours, it was extruded into a single screw extruder (manufactured by Shibaura Kikai Co., Ltd., cylinder set temperature: 250°C) and T die (width 300 mm, set temperature: 250°C). , a transparent plastic film base material composed of polycarbonate resin with a thickness of 40 μm was produced using a film forming apparatus equipped with a cooling roll (set temperature: 120 to 130° C.) and a winder.

(Preparation of anti-glare film 6)

In forming the anti-glare layer, anti-glare film 6 of Production Example 6 was produced in the same manner as Production Example 1, except that the transparent plastic film base material made of the polycarbonate resin obtained above was used as the base material.

Production example 7

(Preparation of anti-glare film 7)

In the formation of the anti-glare layer, the anti-glare properties of Preparation Example 7 were obtained in the same manner as Preparation Example 1, except that a transparent plastic film base material (CPI film, manufactured by KOLON, brand name "C_50_D", thickness: 50 μm) was used as the base material. Film 7 was prepared.

Production example 8

(Preparation of anti-glare film 8)

In the formation of the anti-glare layer, this production example was carried out in the same manner as production example 1, except that a transparent plastic film substrate (TAC film, manufactured by Fujifilm Co., Ltd., brand name “TD80UL”, thickness: 80 μm) was used as the substrate. Anti-glare film 8 was prepared.

Production example 9

(Preparation of acrylic 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 were mixed under a nitrogen atmosphere. It was stirred at 70°C for 1 hour. Next, 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, and reaction was performed at 70°C for 2 hours, then the temperature was raised to 80°C and reaction was performed for 2 hours. Thereafter, the reaction solution was heated to 130°C, toluene, chain transfer agent, and unreacted monomer were removed by drying, and a solid acrylic oligomer (acrylic oligomer A) was obtained. The weight average molecular weight of acrylic oligomer A was 5100, and the glass transition temperature (Tg) was 130°C.

[Preparation of prepolymer and acrylic adhesive composition 1]

As a monomer component for forming a prepolymer, 60 parts by weight of lauryl acrylate (LA), 22 parts by weight of 2-ethylhexyl acrylate (2EHA), 8 parts by weight of 4-hydroxybutylacrylate (4HBA), and N-vinyl-2 - 10 parts by weight of pyrrolidone (NVP) and 0.1 part by weight of “Omnirad184” manufactured by BASF and 0.1 part by weight of “Omnirad651” manufactured by BASF as photopolymerization initiators were mixed, polymerization was performed by irradiation with ultraviolet rays, and a prepolymer composition was obtained. To 100 parts by weight of the above prepolymer composition, as post-addition components, 37 parts by weight of 2-ethylhexyl acrylate (2EHA) and 1,6-hexanediol diacrylate (product name "A-HD-N", Shinnakamura Chemical) After adding 0.08 parts by weight of the acrylic oligomer A (manufactured by Shin-Etsu Chemical Co., Ltd.), 6 parts by weight of the above-described acrylic oligomer A, and 0.3 parts by weight of a silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical), they were mixed uniformly to prepare acrylic adhesive composition 1. did.

Production example 10

(Preparation of prepolymer and acrylic adhesive composition 2)

As the monomer component for forming the prepolymer, 67 parts by weight of butylacrylate (BA), 14 parts by weight of cyclohexyl acrylate (“Viscott #155” manufactured by Osaka Yuki Chemical Co., Ltd.), and 19 parts by weight of 4-hydroxybutylacrylate (4HBA) parts by weight, and as a photopolymerization initiator, 0.09 parts by weight of "Omnirad184" manufactured by BASF and 0.09 parts by weight of "Omnirad651" manufactured by BASF were mixed, polymerization was performed by irradiation with ultraviolet rays, and a prepolymer composition was obtained. In 100 parts by weight of the above prepolymer composition, post-addition components include 9 parts by weight of hydroxylethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutylacrylate (4HBA), and dipentaerythritol hexaacrylate (DPHA). After adding 0.02 parts by weight, 0.3 parts by weight of a photopolymerization initiator (“Omnirad651” manufactured by BASF), and 0.35 parts by weight of a silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical), they were mixed uniformly to prepare an acrylic adhesive composition 2. .

Production example 11

(Preparation of prepolymer and acrylic adhesive composition 3)

As a monomer component for forming a prepolymer, 78 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of hydroxylethyl acrylate (HEA), and 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and photopolymerization. As an initiator, 0.035 parts by weight of "Omnirad184" manufactured by BASF and 0.035 parts by weight of "Omnirad651" manufactured by BASF were blended, polymerization was performed by irradiation with ultraviolet rays, and a prepolymer composition was obtained. In 100 parts by weight of the above prepolymer composition, as post-addition components, 17.6 parts by weight of hydroxylethyl acrylate (HEA) and 1,6-hexanediol diacrylate (product name "A-HD-N", Shinnakamura Chemical Co., Ltd. After adding 0.294 parts by weight of Shikigai Co., Ltd., 11.8 parts by weight of the above-described acrylic oligomer A, and 0.35 parts by weight of a silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical), they were mixed uniformly to prepare an acrylic adhesive composition 3. .

Example 1

(Preparation of inorganic adhesive layer 1)

A polyethylene terephthalate (PET) film (“Diafoil MRF75” manufactured by Mitsubishi Chemical) with a thickness of 75 μm provided with a silicone-based release layer on the surface was used as a substrate (double-release film), and the above-mentioned acrylic adhesive composition 1 was applied on the release layer of the substrate. It was applied to a thickness of 25㎛ to form an application layer. On this application layer, a release layer of PET film (“Diafoil MRE75” manufactured by Mitsubishi Chemical Company) with a thickness of 75 μm, one side of which had been treated with silicone peeling, was bonded as a cover sheet (combined peeling film). This laminate was photocured by irradiating ultraviolet rays from the cover sheet side with a black light whose position was adjusted so that the irradiation intensity on the irradiation surface immediately below the lamp was 5 mW/cm2, and an inorganic material with a thickness of 25 μm was formed. Adhesive layer 1 was obtained.

(Preparation of adhesive tape 1)

By peeling off one side of the release film from the inorganic adhesive layer 1 obtained above and attaching the exposed adhesive side to the non-glare layer side of the anti-glare film 1 shown in Production Example 1, anti-glare film 1/adhesive layer 1/release film is obtained. Adhesive tape 1 containing was obtained.

Example 2

(Preparation of adhesive tape 2)

In the same manner as in Example 1 except that the anti-glare film 2 described above was used, adhesive tape 2 comprising anti-glare film 2/adhesive layer 1/release film was obtained.

Example 3

(Preparation of inorganic adhesive layer 2)

Except for using the acrylic adhesive composition 2 described above, the same procedure as in Example 1 was performed to obtain an inorganic adhesive layer 2 with a thickness of 25 μm.

(Preparation of adhesive tape 3)

In the same manner as in Example 1, except that the inorganic adhesive layer 2 obtained above was used, adhesive tape 3 comprising anti-glare film 1/adhesive layer 2/release film was obtained.

Example 4

(Preparation of adhesive tape 4)

In the same manner as in Example 1, except that the anti-glare film 3 described above was used, adhesive tape 4 comprising anti-glare film 3/adhesive layer 1/release film was obtained.

Example 5

(Preparation of adhesive tape 5)

In the same manner as in Example 1, except that the anti-glare film 4 described above was used, adhesive tape 5 comprising anti-glare film 4/adhesive layer 1/release film was obtained.

Example 6

(Preparation of adhesive tape 6)

In the same manner as in Example 1, except that the anti-glare film 5 described above was used, adhesive tape 6 comprising anti-glare film 5/adhesive layer 1/release film was obtained.

Example 7

(Preparation of adhesive tape 7)

In the same manner as in Example 1, except that the anti-glare film 6 described above was used, adhesive tape 7 comprising anti-glare film 6/adhesive layer 1/release film was obtained.

Example 8

(Preparation of adhesive tape 8)

In the same manner as in Example 1, except that the anti-glare film 7 described above was used, adhesive tape 8 comprising anti-glare film 7/adhesive layer 1/release film was obtained.

Comparative Example 1

(Preparation of adhesive tape 9)

In the same manner as in Example 1, except that the anti-glare film 8 described above was used, adhesive tape 9 comprising anti-glare film 8/adhesive layer 1/release film was obtained.

Comparative Example 2

(Preparation of inorganic adhesive layer 3)

Except for using the acrylic adhesive composition 3 described above, the same procedure as in Example 1 was performed to obtain an inorganic adhesive layer 3 with a thickness of 25 μm.

(Preparation of adhesive tape 10)

Except for using the anti-glare film 8 and the inorganic adhesive layer 3 described above, the same procedure as in Example 1 was performed to obtain adhesive tape 10 including anti-glare film 8/adhesive layer 3/release film.

(evaluation)

The following evaluations were performed using the adhesive tapes obtained in the above examples and comparative examples. The evaluation method is shown below. The results are shown in Table 2.

(1) Average dimensional change rate

The adhesive tape prepared in each example and each comparative example was cut into a roughly square shape when viewed from the plane of 100 mm in the MD direction x 100 mm in the TD direction, and scratches in a cross pattern were created at each of the four corners to produce a test piece.

In the test piece before heating (25°C), the distance (length) between the MD direction of the scratch (cross pattern center) and the distance (length) between the TD direction were measured using a CNC three-dimensional measuring machine (Mittoyo Corporation, “LEGEX774”). It was measured at room temperature (25°C) using . As a result, the length before heating was obtained in each of the MD and TD directions.

Next, the test piece was heated for 500 hours in an environment of 60°C and 90% relative humidity, and then allowed to cool at room temperature (25°C) for 1 hour. After that, the distance between the MD and TD directions of the scratches was measured using a CNC three-dimensional measuring machine. As a result, the length after heating was obtained in each of the MD and TD directions. Next, the dimensional change rates A1 and A2 were calculated in each of the MD and TD directions using the following formula, and the average value was taken as the average dimensional change rate (%). Additionally, the ratio (A1/A2) of the dimensional change rate in the MD direction to the dimensional change rate in the TD direction was obtained.

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

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

(2) Maximum curl amount

The release film of the adhesive tape prepared in each example and each comparative example was peeled off, a PET film (manufactured by Mitsubishi Chemical Co., Ltd., brand name “Diafoil T100E50”, thickness: 50 μm) was attached, and the obtained laminate was formed into a 100 mm It was cut into a roughly square shape when viewed from a 100 mm plane, and a test piece was produced.

Next, the test piece was heated for 500 hours in an environment of 60°C and 90% relative humidity, 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 surface where the curl was convex was at the bottom, the distance from the horizontal surface at each of the four points was measured, and the distance of the longest point from the horizontal surface was taken as the maximum amount of curl (mm).

In addition, the maximum curl amount measured with the PET film side of the laminate placed on a horizontal plane is +, and the maximum curl amount measured with the substrate side of the laminate (opposite side of the PET film) placed on a horizontal plane is placed on the bottom side. The maximum curl amount was set to -.

(3) Reflectance

The adhesive surface of the adhesive tape obtained in each example and each comparative example was affixed to a black acrylic board to serve as a test piece. The obtained test piece was placed on a spectrophotometer U4100 (manufactured by Hitachi High-Technologies) with the adhesive tape side facing the light source, and the reflectance (%) in the visible light region at 5° regular reflection was measured.

(4) Haze

The 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 Shikisai Kensho Co., Ltd.). Measurements were repeated three times, and the average value was taken as the measured value.

(5) Shear force of adhesive layer

The adhesive tapes obtained in each Example and Comparative Example were cut to a size of 10 mm in width and 100 mm in length, and after peeling off the separator, an acrylic resin plate was placed so that the adhesion (adhesion) area of the adhesive layer of the adhesive tape was 1 cm2. It was bonded to Acrylite (manufactured by Mitsubishi Chemical) and pulled in the shear direction at a peeling speed of 0.06 mm/min at 23°C, and the maximum load (N/cm2) at that time was used 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 to produce a test sample with a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, inserted into a parallel plate, and dynamic viscoelasticity measurement was performed using the “Advanced Rheometric Expansion System (ARES)” manufactured by Rheometric Scientific under the following conditions, and the measurement results were obtained. From this, the storage elastic modulus G' and loss tangent tanδ at each temperature were read. In addition, the temperature at which tan δ reached its maximum was set as the glass transition temperature of the adhesive layer.

(Measuring conditions)

Deformation Mode: Torsion

Measurement frequency: 1Hz

Measurement temperature: -70℃ to 150℃

(7) 300% tensile residual stress value of adhesive layer

The adhesive layer obtained in each example and comparative example was cut to a size of 40 mm By bonding them together, an adhesive layer sample with a size of about 10 mm x 40 mm and a thickness of about 400 μm was produced. The adhesive layer sample was set in a tensile tester with the distance between chucks set to 20 mm, and stretched by 60 mm (300%) at a tensile speed of 200 mm/min (the distance between chucks after tensioning was 80 mm). The 60 mm tensioned position was held fixed for 300 seconds, the subsequent stress value was measured, and the “300% tensile residual stress value” was calculated using the following formula.

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

(8) Deformation A, Deformation B, and Restoration Rate

The separator was peeled from the adhesive layer obtained in each example and comparative example, and a plurality of adhesive layers were laminated to produce a test sample with a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm and used as a sample. did. The shear test to determine “strain amount A”, “strain amount B”, and “recovery rate” was conducted in the form shown in FIG. 5. Specifically, using the "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific, which has parallel plates 41 and 42 with a diameter of 7.9 mm, the upper surface of the parallel plate 41 and the bottom surface of the parallel plate 42 are, Each sample was aligned and brought into contact with the bottom and top surfaces of the adhesive layer (Figure 5(b)). Next, dynamic viscoelasticity was measured under the following measurement conditions, and the deformation amount A was measured at 500 Pa and 600 seconds (Figure 5(c)), and then maintained at 0 Pa and 1800 seconds (Figure 5(d)). The amount of deformation B was read, and the restoration rate was calculated using the following equation.

(Measuring conditions)

Deformation Mode: Torsion

Measurement program: 500Pa, hold for 600 seconds, then 0Pa, hold for 1800 seconds.

Measurement temperature: 60℃

Axial Force: 0.2N

Restoration rate: (strain amount A-strain amount B)/strain amount A×100

(9) Humidity expansion rate

The adhesive tapes obtained in each Example and Comparative Example were cut to a width of 2 mm in the TD direction and a length of 20 mm in the MD direction, and measurement was performed under the following conditions using a HC-TMA4000SA type manufactured by Bruker AXS Co., Ltd.

(Measuring conditions)

Deformation Mode: Tensile

Load: 2g

Holding time: 5 hours

Temperature increase rate: 5% RH/min

Measurement atmosphere: Maintained at 60°C with 30% relative humidity until saturated, controlled at 60°C with 60% relative humidity.

(10) Humidity expansion coefficient of the substrate

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

The humidity expansion coefficient (α) was calculated using the following equation.

α=ΔL/{(T2-T1)×L}

T1: Low humidity side humidity (%RH) to calculate humidity expansion coefficient

T2: Humidity on the high humidity side (%RH) to determine the humidity expansion coefficient

ΔL: Difference between the length at T1 and the length at T2 regarding the test piece (㎛)

L: Length of test piece at room temperature (60℃) (㎛)

(11) Glass transition point (Tg) of the substrate

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

Device: Q-2000 from TA Instruments

Container: Aluminum container

Temperature program: -30℃→300℃

Temperature increase rate: 10℃/min

Atmospheric gas: N ₂ (50ml/min)

(12) Check the gap between adhesive tapes

Four adhesive tapes obtained in Examples and Comparative Examples were cut into 5 cm x 5 cm pieces and attached to glass without gaps, heated for 500 hours in an environment of 60°C and 90% relative humidity, and then allowed to cool at room temperature (25°C) for 1 hour. Thereafter, the glass was placed on the backlight, and the gap between the adhesive tapes when irradiated with light from the backlight was visually observed and evaluated based on the following criteria.

○… Gaps between the adhesive tapes were not confirmed.

×… Gaps between the adhesive tapes were confirmed.

(13) Confirmation of peeling of adhesive

The end of the adhesive tape of the sample heated at 60°C and 90% relative humidity for 500 hours, used to confirm the gap between the adhesive tapes, was confirmed under an optical microscope and evaluated based on the following criteria.

○… No peeling was observed in the adhesive tape.

×… Peeling was confirmed in the adhesive tape.

Below, variations of the present invention are added.

[Appendix 1] An optical adhesive tape having a laminated structure in which a substrate having a first side and a second side, and an adhesive layer is laminated on the first side of the substrate,

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

An optical adhesive tape, characterized in that 1 cm 2 of the adhesive layer of the adhesive layer is bonded to a resin plate and the shear force is 20 N/cm 2 or less when stretched in the shear direction at 23°C at a tensile speed of 0.06 mm/min.

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

The maximum curl amount shown below when the adhesive layer of the optical adhesive tape is bonded to a PET film with a thickness of 50 μm and then cut into 10 cm squares and heated for 500 hours in an environment of 60°C and 90% relative humidity is calculated as D[ mm], the optical adhesive tape described in Appendix 1 satisfies the following formula.

|C×D|≤3

· Maximum curl amount: The laminate is placed on a horizontal surface so that the convex curled surface is at the bottom, and the highest curl amount among the four corners is taken as the maximum curl amount D [mm]. The maximum amount of curl measured with the PET film side of the above-mentioned laminate placed on a horizontal plane facing down is +, and the maximum curl amount measured with the base material side of the above-mentioned laminate placed on a horizontal surface facing down is taken as -.

[Appendix 3] The optical adhesive tape according to Supplementary Note 1 or 2, wherein the glass transition point (Tg) of the above description is 60°C or higher.

[Appendix 4] The optical adhesive tape according to any one of Appendices 1 to 3, wherein the adhesive layer has a glass transition point (Tg) of -10°C or lower.

[Appendix 5] The optical adhesive tape according to any one of Appendices 1 to 4, wherein the optical adhesive tape has a humidity expansion rate of 0.1% or less when the optical adhesive tape is humidified from a relative humidity of 30% at 60°C to a relative humidity of 60% at 60°C.

[Appendix 6] The optical adhesive tape according to any one of Appendices 1 to 5, wherein the humidity expansion coefficient of the above description is 5×10 ^-5 /%RH or less.

[Supplementary Note 7] The optical adhesive tape according to any one of Supplementary Notes 1 to 6, wherein the second side of the substrate is subjected to anti-reflection treatment and/or anti-glare treatment.

[Appendix 8] The optical adhesive tape according to any one of Appendices 1 to 7, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer.

[Appendix 9] An image display device in which the optical adhesive tape according to any one of Appendices 1 to 8 and an image display panel are laminated.

[Supplementary Note 10] A tiling display in which a plurality of image display devices described in Supplementary Note 9 are arranged.

10A, 10B: Optical adhesive tape
1: Description
1a: first side of substrate
1b: Second side of substrate
2: Adhesive layer
3: Anti-reflective and/or anti-glare treatment
20: Image display device
4: Image display panel
30: Tiling display
31: support substrate
40: Adhesive layer
41, 42: Parallel plate

Claims (10)

An optical adhesive tape having a laminated structure in which a substrate having a first side and a second side, and an adhesive layer is laminated on the first side of the substrate,
When the optical adhesive tape is heated for 500 hours in an environment of 60°C and 90% relative humidity, the average dimensional change rate in the width direction and machine direction is within ±0.15%,
An optical adhesive tape, characterized in that 1 cm 2 of the adhesive layer of the adhesive layer is bonded to a resin plate and the shear force is 20 N/cm 2 or less when stretched in the shear direction at 23°C at a tensile speed of 0.06 mm/min. The method of claim 1, wherein the average dimensional change rate in the width direction and machine direction when the optical adhesive tape is heated for 500 hours in an environment of 60° C. and 90% relative humidity is set to C [%],
The maximum curl amount shown below when the adhesive layer of the optical adhesive tape is bonded to a PET film with a thickness of 50 μm and then cut into 10 cm squares and heated for 500 hours in an environment of 60°C and 90% relative humidity is calculated as D[ mm], an optical adhesive tape that satisfies the following formula.
|C×D|≤3
· Maximum curl amount: The laminate is placed on a horizontal surface so that the convex curled surface is at the bottom, and the highest curl amount among the four corners is taken as the maximum curl amount D [mm]. The maximum amount of curl measured with the PET film side of the above-mentioned laminate placed on a horizontal plane facing down is +, and the maximum curl amount measured with the base material side of the above-mentioned laminate placed on a horizontal surface facing down is taken as -. The optical adhesive tape according to claim 1 or 2, wherein the substrate has a glass transition point (Tg) of 60°C or higher. The optical adhesive tape according to any one of claims 1 to 3, wherein the 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 optical adhesive tape has a humidity expansion rate of 0.1% or less when the optical adhesive tape is humidified from a relative humidity of 30% at 60°C to a relative humidity of 60% at 60°C. The optical adhesive tape according to any one of claims 1 to 5, wherein the substrate has a humidity expansion coefficient of 5×10 ^-5 /%RH or less. The optical adhesive tape according to any one of claims 1 to 6, wherein the second surface of the substrate is treated with anti-reflection treatment and/or anti-glare treatment. The optical adhesive tape according to any one of claims 1 to 7, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer. An image display device in which the optical adhesive tape according to any one of claims 1 to 8 and an image display panel are laminated. A tiling display in which a plurality of image display devices according to claim 9 are arranged in a row.