Adhesive Sheet, Laminate, and Display Body

Abstract

To provide an adhesive sheet equipped with an adhesive layer in which the adhesive layer follows unevenness in a good condition, which has excellent blister resistance, and does not generate optical irregularity.SOLUTION: An adhesive sheet has an adhesive layer for bonding a first member and a second member, where the total light transmittance of the adhesive layer is 85% or less. In the case where one principal surface of the adhesive layer is surface A and the other principal surface is surface B, surface A unevenness followability (%) showing the followability of the surface A to unevenness when the surface A is bonded to an adherend having unevenness, and surface B unevenness followability (%) showing the followability of the surface B to unevenness when the surface B is bonded to an adherend having unevenness are different, and the surface A unevenness followability and the surface B unevenness followability exceed 0%.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to an adhesive sheet, a laminate, and a display body.

Background Art

[0002] In recent years, various instruments provided on the instrument panel of an automobile, a car navigation system, a console, or various mobile electronic devices such as a smartphone and a tablet terminal are equipped with a display (display body) using a display body module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, or the like.

[0003] Such a display body module, or a laminate of the display body module and other members, is generally formed by bonding a display body component and other members using an adhesive layer of an adhesive sheet.

[0004] For such a display, when the display is turned off, it is required to impart a sense of unity between the peripheral members of the display, for example, a frame material and the display, to enhance the design property of the display.

[0005] Patent Document 1 discloses that an optical filter laminated on a plasma display panel main body has a colored layer, and the colored layer has an adhesive and a coloring dye.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the invention described in Patent Document 1, the colored layer is provided so as to be in contact with a transparent substrate and a shielding layer formed in a frame shape on the transparent substrate. Therefore, the adhesive that constitutes the colored layer needs to sufficiently follow the unevenness caused by the shielding layer and fill the unevenness so that gaps or the like do not occur in the vicinity of the unevenness.

[0008] However, when the adhesive follows the unevenness, the adhesive may be deformed. When such deformation occurs, there is a problem that changes occur in the optical properties of the adhesive, and optical unevenness (for example, color unevenness) occurs in the light passing through the adhesive layer. As a result, optical unevenness also occurs in the image displayed on the display body.

[0009] In view of such a situation, the present invention aims to provide an adhesive sheet including an adhesive layer that can well follow unevenness, has excellent blister resistance, and further does not cause optical unevenness.

Means for Solving the Problems

[0010] Aspects of the present invention are as follows.

[0011] [1] An adhesive sheet having an adhesive layer for bonding a first member and a second member, The total light transmittance of the adhesive layer is 85% or less, When one main surface of the adhesive layer is defined as surface A and the other main surface is defined as surface B, the A-surface unevenness followability (%) indicating the followability of surface A with respect to the unevenness when surface A is bonded to an adherend having unevenness, and the B-surface unevenness followability (%) indicating the followability of surface B with respect to the unevenness when surface B is bonded to an adherend having unevenness are different, An adhesive sheet in which the A-surface unevenness followability and the B-surface unevenness followability are more than 0%.

[0012] [2] The adhesive sheet according to [1], wherein the adhesive layer is composed of two or more layers.

[0013] [3] The value obtained by subtracting the unevenness followability of the B side from the unevenness followability of the A side is from -20 points to -1 point, and it is the pressure-sensitive adhesive sheet according to [1] or [2].

[0014] [4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the pressure-sensitive adhesive layer contains a coloring component.

[0015] [5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive having a crosslinked structure.

[0016] [6] A laminate including a first member, a second member, and a pressure-sensitive adhesive layer that bonds the first member and the second member to each other, At least one of the first member and the second member has unevenness, The pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to [5].

[0017] [7] A display body including the laminate according to [6].

Advantages of the Invention

[0018] According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer that follows unevenness well, has excellent blister resistance, and further does not cause optical unevenness.

Brief Description of the Drawings

[0019]

Figure 1A

Figure 1B

Figure 2

Modes for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described in detail based on specific embodiments.

[0021] (1. Adhesive sheet) As shown in Fig. 1A, the adhesive sheet 1 according to the present embodiment has an adhesive layer 10 and release sheets 21 and 22. The adhesive layer bonds a first member and a second member. In the present embodiment, the first member and the second member are members (display body constituent members) that constitute a display body.

[0022] The display body is configured by laminating display body constituent members having a predetermined function, and each display body constituent member is bonded via an adhesive layer. At this time, the display body constituent member itself may have unevenness, or unevenness may be formed on the display body constituent member. When the adhesive layer cannot follow the unevenness, the adhesive layer floats in the vicinity of the unevenness and gaps are generated, leading to a deterioration in the image quality of the display body. Therefore, it is required that the adhesive layer sufficiently follows the unevenness and is bonded.

[0023] In addition, among the display body constituent members, there are also members whose material is changed from glass to plastic. When the material is changed to plastic, when the display body constituent member bonded by the adhesive layer is exposed to a high-temperature and high-humidity environment, outgas is generated from the plastic, and there is also a problem that blisters such as bubbles, floating, and peeling occur. Therefore, the adhesive layer is also required to have blister resistance.

[0024] On the other hand, with respect to the display body, in order to enhance the design property, for example, the boundary between the display body constituent members is made less visible, and when the display body is turned off, a sense of unity between the frame material of the display body and the display body is imparted. Such imparting of a sense of unity is performed by controlling the optical properties (for example, total light transmittance) of the adhesive layer.

[0025] However, in the vicinity of unevenness, the adhesive layer may deform in order to follow the unevenness. When such deformation occurs, the optical properties of the adhesive layer change, and the optical properties may differ between the deformed part and the non-deformed part. As a result, the light passing through the adhesive layer is affected, and optical unevenness may occur in the display body. Examples of such optical unevenness include color unevenness when the adhesive layer is colored. The occurrence of optical unevenness such as color unevenness is not preferable because it deteriorates the design and image quality of the display body.

[0026] In order to address the above problems, in this embodiment, the adhesive layer is as described below. The adhesive layer of the adhesive sheet according to this embodiment can suppress optical unevenness even in the vicinity of unevenness while sufficiently following the unevenness, and further improve blister resistance.

[0027] (2. Adhesive layer) The adhesive layer of the adhesive sheet according to this embodiment is composed of an adhesive described later. Further, the adhesive layer may be composed of one layer (single layer) or may be composed of two or more layers. In this embodiment, from the viewpoint of easily realizing the physical properties described later, it is preferable that the adhesive layer has two or more layers.

[0028] The thickness of the adhesive layer is preferably 1 to 2000 μm, more preferably 10 to 1200 μm, still more preferably 40 to 900 μm, particularly preferably 80 to 600 μm, and among them, still more preferably 100 to 400 μm, and most preferably 150 to 250 μm. The above thickness is the total thickness of the plurality of layers when the adhesive layer is composed of a plurality of layers.

[0029] When the adhesive layer is composed of a plurality of layers, the thickness of each adhesive layer is preferably 1 to 1000 μm, more preferably 10 to 600 μm, still more preferably 20 to 300 μm, and particularly preferably 25 to 200 μm.

[0030] (2.1. Physical properties of the adhesive layer) The adhesive layer according to this embodiment has the physical properties as shown below. When the adhesive layer has a plurality of layers, the physical properties shown below are the physical properties shown by the entire adhesive layer.

[0031] (2.1.1. Unevenness followability of the adhesive layer) In this embodiment, of the main surfaces of the adhesive layer, one main surface of the adhesive layer is defined as surface A, and the other main surface is defined as surface B. In FIG. 1A, the main surface 10a of the adhesive layer 10 is surface A, and the main surface 10b is surface B. Also, surface A and surface B are the surfaces that are bonded to the display body constituent member.

[0032] In this embodiment, the unevenness followability on surface A (surface A unevenness followability) and the unevenness followability on surface B (surface B unevenness followability) are controlled. The unevenness followability is an index indicating to what extent the adhesive layer follows the unevenness such as steps of the adherend (display body constituent member) when the adhesive layer is bonded to the adherend. The higher the unevenness followability, the more the unevenness is sufficiently embedded in the adhesive layer even in the vicinity of unevenness with a large height difference, and the bonding can be achieved without forming gaps or the like at the interface between the adhesive layer and the unevenness. The unevenness followability can be calculated by the following formula. Unevenness followability (%) = {(height of the step (μm) where the state of being filled without bubbles, floating, peeling, etc. is maintained after a predetermined durability test) / (thickness of the adhesive layer (μm))} × 100

[0033] Note that the test method for the unevenness followability is as shown in the test examples described later. Also, when the adhesive layer is composed of an active energy ray curable adhesive, the unevenness followability is the unevenness followability when cured with active energy rays after attaching the adherend.

[0034] In this embodiment, the A-side unevenness followability of the adhesive layer and the B-side unevenness followability of the adhesive layer are different, and the A-side unevenness followability and the B-side unevenness followability are greater than 0%. By satisfying the above relationship between the unevenness followability of the A side and the unevenness followability of the B side of the adhesive layer, the adhesive layer can sufficiently follow the unevenness and suppress unevenness in optical properties caused by the unevenness. Furthermore, the blister resistance is also improved.

[0035] The A-side unevenness followability and the B-side unevenness followability are preferably 1% to 50%, more preferably 2% to 40%, still more preferably 3% to 30%, and particularly preferably 4% to 20%.

[0036] Also, the difference between the A-side unevenness followability and the B-side unevenness followability (A-side unevenness followability - B-side unevenness followability) is preferably -20 to -1 point, more preferably -15 to -1.5 points, and still more preferably -10 to -2 points.

[0037] (2.1.2. Total light transmittance of the adhesive layer) The total light transmittance of the adhesive layer according to this embodiment is 85% or less. Thereby, the design property of the display body is improved.

[0038] From the viewpoint of visibility, the total light transmittance is preferably 3% or more, more preferably 10% or more, still more preferably 25% or more, particularly preferably 30% or more, and most preferably 35% or more. From the viewpoint of design property, the total light transmittance is preferably 75% or less, more preferably 65% or less, still more preferably 55% or less, and particularly preferably 50% or less. The total light transmittance in this specification is a value measured according to JIS K7361-1:1997. Further, when the adhesive layer is composed of an active energy ray curable adhesive, the total light transmittance is the total light transmittance when cured with active energy rays after attaching to the adherend.

[0039] (2.1.3. Haze value of the adhesive layer) From the viewpoint that the haze value of the pressure-sensitive adhesive layer according to this embodiment easily satisfies the desired total light transmittance and can achieve both concealability and visibility, it is preferably 0 to 80%, more preferably 0.1 to 60%, still more preferably 0.5 to 40%, particularly preferably 1 to 20%, and most preferably 1.5 to 10%. The haze value in this specification is a value measured in accordance with JIS K7136:2000. Further, when the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, the haze value is the haze value when cured with active energy rays after being attached to the adherend.

[0040] (2.1.4. Adhesion of the pressure-sensitive adhesive layer) In this embodiment, the adhesion of the A surface of the pressure-sensitive adhesive layer to soda-lime glass (hereinafter also referred to as the A surface adhesion) is preferably 1 N / 25 mm or more and 100 N / 25 mm or less. Thereby, sufficient adhesion to the adherend to be bonded can be ensured, and it becomes easy to achieve good step followability and good blister resistance.

[0041] From the above viewpoints, the A surface adhesion is more preferably 5 to 70 N / 25 mm, and still more preferably 10 to 50 N / 25 mm.

[0042] In this embodiment, the adhesion of the B surface of the pressure-sensitive adhesive layer to soda-lime glass (hereinafter also referred to as the B surface adhesion) is preferably 1 N / 25 mm or more and 100 N / 25 mm or less. Thereby, sufficient adhesion to the adherend to be bonded can be ensured, and it becomes easy to achieve good step followability and good blister resistance.

[0043] From the above viewpoints, the B surface adhesion is more preferably 5 to 70 N / 25 mm, and still more preferably 10 to 50 N / 25 mm.

[0044] The above adhesion may be measured by the 180-degree peel method according to JIS Z0237:2009. The specific measurement method is as shown in the test examples described later.

[0045] (When the adhesive layer has two layers) As described above, the adhesive layer according to the present embodiment is preferably two or more layers. Therefore, hereinafter, the case where the adhesive layer has two layers will be described. When the adhesive layer has two layers, as shown in FIG. 1B, the adhesive sheet 1 according to the present embodiment includes an adhesive layer 10 (a first adhesive layer 11 and a second adhesive layer 12), and release sheets 21 and 22.

[0046] The first adhesive layer 11 and the second adhesive layer 12 are laminated to form the adhesive layer 10. In the present embodiment, the main surface 11a that is bonded to the adherend in the first adhesive layer 11 is defined as the A surface, and the main surface 12a that is bonded to the adherend in the second adhesive layer 12 is defined as the B surface.

[0047] (2.3. Physical properties of the first adhesive layer and the second adhesive layer) The physical properties of the first adhesive layer and the second adhesive layer are not particularly limited as long as the physical properties of the entire adhesive layer satisfy the above-described physical properties.

[0048] (2.3.1. Total light transmittance) In the present embodiment, when the first adhesive layer and the second adhesive layer are layers for facilitating satisfaction of the visibility of the entire adhesive layer, the total light transmittance is preferably 85 to 100%, more preferably 88 to 96%, and even more preferably 90 to 93%. When the first adhesive layer and the second adhesive layer are layers for facilitating satisfaction of the design property of the entire adhesive layer, the total light transmittance is preferably 3 to 85%, more preferably 10 to 80%, even more preferably 30 to 75%, particularly preferably 50 to 70%, and preferably 55 to 68% among them. When the first adhesive layer and the second adhesive layer are active energy ray curable, the total light transmittance before and after active energy ray irradiation is preferably within the above range. This makes it easier to satisfy the optical physical properties required for the entire adhesive layer.

[0049] (2.3.2. Haze value) In this embodiment, the haze values of the first adhesive layer and the second adhesive layer are preferably from 0 to 80%, more preferably from 0.01 to 40%, still more preferably from 0.05 to 10%, and even more preferably from 0.1 to 2%. When the first adhesive layer and the second adhesive layer are curable by active energy rays, the haze values before and after irradiation with active energy rays are preferably within the above ranges. This makes it easier to satisfy the optical physical properties required for the entire adhesive layer.

[0050] (2.3.3. Storage Elastic Modulus) In this embodiment, the storage elastic modulus G' at 25°C of the first adhesive layer and the second adhesive layer is preferably from 0.01 to 10 MPa, more preferably from 0.04 to 5 MPa, still more preferably from 0.08 to 2 MPa, particularly preferably from 0.1 to 1.5 MPa, and most preferably from 0.15 to 1.1 MPa.

[0051] When the first adhesive layer and the second adhesive layer are curable by active energy rays, the storage elastic modulus Gb' at 25°C before irradiation with active energy rays is preferably from 0.01 to 1 MPa, more preferably from 0.03 to 0.5 MPa, and still more preferably from 0.05 to 0.2 MPa. On the other hand, the storage elastic modulus Ga' at 25°C after irradiation with active energy rays is preferably from 0.01 to 10 MPa, more preferably from 0.04 to 5 MPa, still more preferably from 0.08 to 1 MPa, and particularly preferably from 0.1 to 0.5 MPa.

[0052] As a result, the first adhesive layer and the second adhesive layer have suitable viscoelasticity, and the adhesion to an adherend such as a display body component becomes good. At the same time, it becomes easier to adjust the above-described adhesive force and the like to a desired range, and good unevenness followability and blister resistance are exhibited. In particular, it becomes easier to satisfy the ratio of the storage elastic modulus described later, and in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0053] In addition, in the case where one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contains a coloring component described later and the other pressure-sensitive adhesive layer does not contain the coloring component, the storage elastic modulus G1b' of the pressure-sensitive adhesive layer containing the coloring component at 25°C before active energy ray irradiation and the storage elastic modulus G2b' of the pressure-sensitive adhesive layer not containing the coloring component at 25°C before active energy ray irradiation, the ratio (G1b' / G2b') is preferably from 1.1 to 10000, more preferably from 1.2 to 1000, still more preferably from 1.3 to 100, even more preferably from 1.4 to 50, particularly preferably from 1.5 to 25, and most preferably from 1.6 to 15.

[0054] In the case where one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contains a coloring component described later and the other pressure-sensitive adhesive layer does not contain the coloring component, the storage elastic modulus G1a' of the pressure-sensitive adhesive layer containing the coloring component at 25°C after active energy ray irradiation and the storage elastic modulus G2a' of the pressure-sensitive adhesive layer not containing the coloring component at 25°C before active energy ray irradiation, the ratio (G1a' / G2a') is preferably from 1.11 to 10000, more preferably from 1.15 to 1000, still more preferably from 1.2 to 100, even more preferably from 1.24 to 50, particularly preferably from 1.28 to 25, and most preferably from 1.3 to 15.

[0055] By satisfying the above-described ranges for G1b' / G2b' and G1a' / G2a', the resulting pressure-sensitive adhesive sheet is likely to exhibit desired physical properties and exhibits good unevenness followability and blister resistance. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0056] (2.3.4. Gel fraction) In the present embodiment, the gel fraction of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably from 30 to 99%, more preferably from 40 to 90%, still more preferably from 45 to 85%, and particularly preferably from 50 to 80%.

[0057] When the first adhesive layer and the second adhesive layer are curable by active energy rays, the gel fraction before irradiation with active energy rays is preferably 20 to 80%, more preferably 30 to 70%, still more preferably 40 to 60%, and particularly preferably 45 to 53%. On the other hand, the gel fraction after irradiation with active energy rays is preferably 40 to 99%, more preferably 50 to 95%, still more preferably 55 to 90%, and particularly preferably 60 to 80%.

[0058] Thereby, the first adhesive layer and the second adhesive layer have suitable cohesiveness, and it becomes easy to adjust the above-described adhesive force and storage elastic modulus to a desired range, and good unevenness followability and blister resistance are exhibited. Further, it is easy to satisfy the above-described ratio of the storage elastic modulus, and in the vicinity of the unevenness, optical unevenness is suppressed while favorably following the unevenness.

[0059] (2.3.5. Adhesive force) In the present embodiment, as described above, since the A surface is the main surface of the first adhesive layer and the B surface is the main surface of the second adhesive layer, the adhesive force of the first adhesive layer preferably satisfies the range of the A surface adhesive force described above, and the adhesive force of the second adhesive layer preferably satisfies the range of the B surface adhesive force described above.

[0060] (2.4. Composition of the first adhesive layer and the second adhesive layer) If the pressure-sensitive adhesive layer according to the present embodiment is configured to have the above physical properties, the compositions of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are not particularly limited. For example, acrylic pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, rubber pressure-sensitive adhesives, and silicone pressure-sensitive adhesives are exemplified. Further, the pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solvent-free type. Furthermore, the pressure-sensitive adhesive may be curable by active energy rays or may not be curable by active energy rays. Furthermore, the pressure-sensitive adhesive may have a crosslinked structure or may not have a crosslinked structure. And, as the material constituting the pressure-sensitive adhesive, from the perspective of SDGs, a material with a high biomass content may be used, a recyclable or reusable material may be used, or a recycled or reused material may be used. Note that the pressure-sensitive adhesives constituting the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the same or different.

[0061] In the present embodiment, from the viewpoint of ease of realizing the above-described physical properties and from the viewpoints of adhesive physical properties, optical properties, etc., as the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, an acrylic pressure-sensitive adhesive is preferable, and an acrylic pressure-sensitive adhesive having a crosslinked structure is more preferable.

[0062] However, from the viewpoint of controlling so that the A-side unevenness followability and the B-side unevenness followability are different, the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer preferably have different adhesive compositions, and more preferably have different monomer compositions of the main polymer.

[0063] The acrylic pressure-sensitive adhesive having a crosslinked structure is preferably an adhesive obtained by crosslinking a pressure-sensitive adhesive composition (hereinafter sometimes referred to as "pressure-sensitive adhesive composition P") containing a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B). With such an adhesive, it is easy to satisfy the above-described physical properties, and a good adhesive force is easily obtained. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Also, the concept of "copolymer" is included in "polymer".

[0064] (2.4.1. (Meth)acrylate polymer) (Meth)acrylate polymer (A) preferably contains a reactive functional group-containing monomer having a reactive functional group that reacts with a crosslinking agent (B) described later in the molecule as a monomer unit constituting the polymer. The reactive functional group derived from this reactive functional group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and an adhesive having a desired cohesive force can be obtained.

[0065] (2.4.1.1. Reactive functional group-containing monomer) Examples of the reactive functional group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer or a carboxy group-containing monomer having excellent reactivity with the crosslinking agent (B) is preferable. Further, a hydroxyl group-containing monomer and a carboxy group-containing monomer may be used in combination.

[0066] Among these, from the viewpoints of the reactivity of the hydroxyl group in the obtained (meth)acrylate polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers, (meth)acrylic acid hydroxyalkyl esters having a hydroxyalkyl group having 1 to 4 carbon atoms are preferable. Specifically, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. are preferably mentioned, and particularly, 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate is preferably mentioned. These may be used alone or in combination of two or more.

[0067] Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoints of the reactivity with the crosslinking agent (B) exhibited by the carboxy group in the resulting (meth)acrylate polymer (A) and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0068] Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, and the like. These may be used alone or in combination of two or more. Note that the nitrogen atom-containing monomer described later is excluded from this amino group-containing monomer.

[0069] When the (meth)acrylate polymer (A) contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, the (meth)acrylate polymer (A) preferably contains the reactive functional group-containing monomer in an amount of 1 to 40% by mass, more preferably 2 to 35% by mass. In particular, when the reactive functional group-containing monomer is a hydroxyl group-containing monomer, the (meth)acrylate polymer (A) preferably contains the hydroxyl group-containing monomer in an amount of 5 to 32% by mass, more preferably 10 to 30% by mass, still more preferably 15 to 28% by mass, and particularly preferably 18 to 26% by mass. Further, when the reactive functional group-containing monomer is a carboxy group-containing monomer, the (meth)acrylate polymer (A) preferably contains the carboxy group-containing monomer in an amount of 3 to 25% by mass, more preferably 4 to 15% by mass, still more preferably 5 to 10% by mass. Thereby, a good crosslinked structure is formed in the resulting adhesive, and an adhesive having a relatively high cohesive force and excellent blister resistance can be obtained. In addition, the resulting adhesive is likely to satisfy desired adhesive physical properties, optical properties, etc. In particular, in the vicinity of unevenness, although it follows the unevenness well, optical unevenness is suppressed.

[0070] The (meth)acrylic acid ester polymer (A) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, by not containing a carboxyl group-containing monomer, even when there are substances that cause problems due to acid on the adhesion target of the adhesive, such as a transparent conductive film or a metal film like indium tin oxide (ITO), etc., it is possible to suppress problems caused by acid to them (corrosion, change in resistance value, etc.).

[0071] Here, "not containing a carboxyl group-containing monomer" means substantially not containing a carboxyl group-containing monomer. In addition to not containing a carboxyl group-containing monomer at all, it also allows containing a carboxyl group-containing monomer to such an extent that corrosion of a transparent conductive film, metal wiring, etc. by the carboxyl group does not occur. Specifically, in the (meth)acrylic acid ester polymer (A), as a monomer unit, it is allowed to contain a carboxyl group-containing monomer in an amount of less than 0.1% by mass, preferably 0.05% by mass or less, more preferably 0.01% by mass or less.

[0072] (2.4.1.2. (Meth)acrylic acid alkyl ester) The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms as a monomer unit constituting the polymer. Thereby, the adhesive can exhibit preferable adhesiveness. Further, from the viewpoint that a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms can exhibit more preferable adhesiveness, it preferably has a linear or branched structure.

[0073] Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, and the like.

[0074] Among these, from the viewpoint of further improving the adhesiveness, (meth)acrylic acid esters having 1 to 12 carbon atoms in the alkyl group are preferred, and (meth)acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are more preferred. Specifically, methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate are preferred, and methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

[0075] The (meth)acrylic acid ester polymer (A) preferably contains 30 to 99% by mass, more preferably 40 to 90% by mass, still more preferably 50 to 80% by mass, and particularly preferably 55 to 70% by mass of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Thereby, other monomer components for developing desired properties can be introduced in a desired amount into the (meth)acrylic acid ester polymer (A), and it becomes easy to impart suitable adhesive physical properties, optical properties, etc. to the resulting adhesive. In particular, it is excellent in unevenness followability and blister resistance, and in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0076] (Meta)acrylic acid ester polymer (A) preferably contains, as a monomer unit constituting the polymer, a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer). Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of this in the polymer widens the distance between the polymers, and the resulting pressure-sensitive adhesive can be made excellent in flexibility. As a result, it becomes easier to satisfy physical properties such as the unevenness followability and adhesive strength described above, and the unevenness followability becomes good.

[0077] The carbocyclic ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond in part. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure (polycyclic structure) such as a bicyclic or tricyclic structure. From the viewpoint of appropriately setting the distance between the obtained (meta)acrylic acid ester polymers (A) and imparting high stress relaxation properties to the pressure-sensitive adhesive, the above alicyclic structure is preferably a polycyclic structure. Further, in consideration of the compatibility between the (meta)acrylic acid ester polymer (A) and other components, the above polycyclic structure is particularly preferably a bicyclic to tetracyclic structure. Also, from the viewpoints of imparting stress relaxation properties and compatibility as described above, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the part forming the ring, and when a plurality of rings exist independently, referring to the total number of carbon atoms thereof) is usually preferably 5 to 15, and more preferably 7 to 10.

[0078] Examples of the alicyclic structure-containing monomer specifically include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, and the like. Among these, dicyclopentanyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10), adamantyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10), or isobornyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 7), which exhibit more excellent unevenness followability, are preferred. Particularly, isobornyl (meth)acrylate is preferred, and isobornyl acrylate is more preferred. These may be used alone or in combination of two or more.

[0079] (Meth)acrylate polymer (A) preferably contains 1 to 30% by mass, more preferably 3 to 26% by mass, still more preferably 6 to 22% by mass, and particularly preferably 9 to 18% by mass of the alicyclic structure-containing monomer when the polymer contains the alicyclic structure-containing monomer as a monomer unit constituting the polymer. Thereby, it becomes easier to satisfy the physical properties such as the unevenness followability and the adhesive strength described above, and the unevenness followability is improved. Particularly, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0080] (Meta)acrylic acid ester polymer (A) preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By incorporating the nitrogen atom-containing monomer as a constituent unit into the polymer, a predetermined polarity can be imparted to the adhesive, making it excellent in affinity even for a substrate having a certain degree of polarity. From the viewpoint of imparting appropriate rigidity to the (meta)acrylic acid ester polymer (A), a monomer having a nitrogen-containing heterocyclic ring is preferred as the nitrogen atom-containing monomer. Further, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the resulting adhesive, it is preferable that the nitrogen atom-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used for the polymerization to form the (meta)acrylic acid ester polymer (A).

[0081] Examples of the monomer having a nitrogen-containing heterocyclic ring include N-(meta)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meta)acryloylpyrrolidone, N-(meta)acryloylpiperidine, N-(meta)acryloylpyrrolidine, N-(meta)acryloylaziridine, aziridinylethyl (meta)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N-(meta)acryloylmorpholine, which exhibits more excellent adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred. These may be used alone or in combination of two or more.

[0082] When the (meta)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, it is preferably contained in an amount of 1 to 20% by mass, more preferably 2 to 16% by mass, still more preferably 3 to 12% by mass, and particularly preferably 4 to 8% by mass. Thereby, it becomes easier to satisfy the physical properties such as the unevenness followability and adhesive strength described above, and the unevenness followability becomes good. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0083] (Meta)acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As other monomers, monomers not containing reactive functional groups are preferred in order not to inhibit the above-described actions of the reactive functional group-containing monomers. Examples of such monomers include (meta)acrylic acid alkoxyalkyl esters such as methoxyethyl (meta)acrylate and ethoxyethyl (meta)acrylate, vinyl acetate, styrene, and the like. These may be used alone or in combination of two or more.

[0084] (Meta)acrylic acid ester polymer (A) is preferably a linear polymer. Thereby, entanglement of molecular chains is likely to occur, and improvement in cohesive force can be expected. Therefore, it becomes easier to satisfy physical properties such as the above-described uneven following rate and adhesive force, and the uneven following property becomes good.

[0085] (Meta)acrylic acid ester polymer (A) is preferably a solution polymer obtained by a solution polymerization method. Thereby, it becomes easier to obtain a polymer of high molecular weight, and improvement in cohesive force can be expected. Therefore, it becomes easier to satisfy physical properties such as the above-described uneven following rate and adhesive force, and the uneven following property becomes good. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0086] (Meta)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer in terms of the polymerization mode.

[0087] The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably from 100,000 to 3,000,000, more preferably from 200,000 to 2,500,000. When the monomer unit constituting the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer without containing a carboxy group, the weight average molecular weight is preferably from 300,000 to 1,800,000, more preferably from 350,000 to 1,200,000, still more preferably from 400,000 to 900,000, and particularly preferably from 450,000 to 750,000. When the monomer unit constituting the (meth)acrylic acid ester polymer (A) contains a carboxy group without containing a hydroxyl group-containing monomer, the weight average molecular weight is preferably from 500,000 to 2,300,000, more preferably from 1,000,000 to 2,200,000, still more preferably from 1,500,000 to 2,100,000. Thereby, it becomes easier to satisfy the physical properties such as the unevenness followability and adhesiveness described above, and the unevenness followability becomes good. In particular, in the vicinity of the unevenness, while following the unevenness well, optical unevenness is suppressed. The weight average molecular weight in this specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC) method.

[0088] In the pressure-sensitive adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more.

[0089] (2.4.2. Crosslinking agent (B)) The crosslinking agent (B) can crosslink the (meth)acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P and can favorably form a three-dimensional network structure. Thereby, the cohesive force of the obtained pressure-sensitive adhesive is improved, it becomes easier to satisfy the physical properties such as the unevenness followability and adhesiveness described above, and the unevenness followability becomes good. In particular, in the vicinity of the unevenness, while following the unevenness well, optical unevenness is suppressed.

[0090] As the crosslinking agent (B), any substance can be used as long as it reacts with the reactive group of the (meth)acrylate polymer (A). For example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. are exemplified. When the reactive functional group of the (meth)acrylate polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. On the other hand, when the reactive functional group of the (meth)acrylate polymer (A) is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group, and it is also preferable to use an isocyanate-based crosslinking agent from the viewpoint of easily obtaining a desired crosslinked structure. Note that the crosslinking agent (B) can be used alone or in combination of two or more.

[0091] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, etc., and their biuret forms, isocyanurate forms, and further adduct forms which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Among these, from the viewpoint of reactivity with the hydroxyl group, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable.

[0092] Examples of the epoxy crosslinking agent include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, and the like. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with the carboxy group.

[0093] The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 to 10 parts by mass, more preferably 0.04 to 5 parts by mass, still more preferably 0.08 to 1 part by mass, and particularly preferably 0.12 to 0.5 part by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A). Thereby, the resulting pressure-sensitive adhesive exhibits good cohesive force, easily satisfies physical properties such as the unevenness followability and adhesive strength described above, and has good unevenness followability. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0094] (2.4.3. Actinic energy ray curable component (C)) In the present embodiment, when the pressure-sensitive adhesives constituting the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are curable by actinic energy rays, the pressure-sensitive adhesive composition P preferably contains an actinic energy ray curable component (C). In a pressure-sensitive adhesive obtained by further curing a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P with actinic energy rays, the actinic energy ray curable components (C) polymerized with each other are presumed to be entangled with the crosslinked structure (three-dimensional network structure) formed by the crosslinking of the (meth)acrylate polymer (A) and the crosslinking agent (B). A pressure-sensitive adhesive having such a higher-order structure easily satisfies physical properties such as the unevenness followability and adhesive strength described above, and is excellent in unevenness followability and blister resistance. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0095] The active energy ray curable component (C) is not particularly limited as long as it cures upon irradiation with active energy rays and can provide the above-described effects, and may be any of a monomer, an oligomer, or a polymer, or a mixture thereof. Among these, from the viewpoint of easily satisfying physical properties such as the above-described unevenness followability and adhesiveness, and from the viewpoint of being more excellent in blister resistance, polyfunctional acrylate monomers are preferably mentioned. Further, from the viewpoint of compatibility with the (meth)acrylate polymer (A), polyfunctional acrylate monomers having a molecular weight of less than 1000 are preferred.

[0096] As the polyfunctional acrylate monomer, difunctional, trifunctional, tetrafunctional, pentafunctional, and hexafunctional acrylate monomers are preferred.

[0097] Examples of the difunctional acrylate monomer include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, and the like.

[0098] Examples of trifunctional acrylate monomers include trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate, and the like.

[0099] Examples of tetrafunctional acrylate monomers include diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and the like. Examples of pentafunctional acrylate monomers include propionic acid-modified dipentaerythritol penta(meth)acrylate, and the like. Examples of hexafunctional acrylate monomers include dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and the like.

[0100] Among these, from the viewpoint of the blister resistance of the resulting adhesive, polyfunctional acrylate monomers containing an isocyanurate structure in the molecule, such as di(acryloxyethyl) isocyanurate, tris(acryloxyethyl) isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate, or polyfunctional acrylate monomers containing a cyclic structure (particularly a cycloalkane structure) in the molecule, such as tricyclodecane dimethanol (meth)acrylate, are preferred. Polyfunctional acrylate monomers having three or more functional groups and containing an isocyanurate structure in the molecule, or polyfunctional acrylate monomers having two or more functional groups and containing a polycyclic structure (particularly a polycyclic structure of cycloalkane) in the molecule, are more preferred. ε-Caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate or tricyclodecane dimethanol (meth)acrylate is particularly preferred, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate or tricyclodecane dimethanol acrylate is more preferred, and ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate is most preferred. These may be used alone or in combination of two or more.

[0101] The content of the active energy ray curable component (C) in the pressure-sensitive adhesive composition P is preferably 1 to 40 parts by mass, more preferably 3 to 32 parts by mass, still more preferably 6 to 24 parts by mass, and particularly preferably 9 to 16 parts by mass or less, based on 100 parts by mass of the (meth)acrylate polymer (A). Thereby, after irradiation with active energy rays, the cohesive force and the like are improved, and it becomes easier to satisfy the physical properties such as the unevenness followability and the adhesive force described above, and the blister resistance and the unevenness followability are more excellent. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0102] (2.4.4. Photoinitiator (D)) In this embodiment, when the pressure-sensitive adhesive composition P contains an active energy ray curable component (C) and uses ultraviolet rays as the active energy ray, the pressure-sensitive adhesive composition P preferably contains a photoinitiator (D). Thereby, the active energy ray curable component (C) can be cured efficiently, and the polymerization curing time and the irradiation amount of ultraviolet rays can be reduced.

[0103] Examples of the photoinitiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin - n - butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2 - dimethoxy - 2 - phenylacetophenone, 2,2 - diethoxy - 2 - phenylacetophenone, 2 - hydroxy - 2 - methyl - 1 - phenylpropan - 1 - one, 1 - hydroxycyclohexyl phenyl ketone, 2 - methyl - 1 - [4 - (methylthio)phenyl] - 2 - morpholino - propan - 1 - one, 4 - (2 - hydroxyethoxy)phenyl - 2 - (hydroxy - 2 - propyl)ketone, benzophenone, p - phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2 - methylanthraquinone, 2 - ethylanthraquinone, 2 - tertiary - butylanthraquinone, 2 - aminoanthraquinone, 2 - methylthioxanthone, 2 - ethylthioxanthone, 2 - chlorothioxanthone, 2,4 - dimethylthioxanthone, 2,4 - diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p - dimethylaminobenzoic acid ester, oligo[2 - hydroxy - 2 - methyl - 1[4 - (1 - methylvinyl)phenyl]propanone], 2,4,6 - trimethylbenzoyl - diphenyl - phosphine oxide, bis(2,4,6 - trimethylbenzoyl)phenylphosphine oxide, and the like. These may be used alone or in combination of two or more.

[0104] Among these, from the viewpoints of being easily cleaved upon ultraviolet irradiation and easily and surely curing the adhesive, a phosphine oxide-based photoinitiator is preferable. Specifically, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. are preferable. Among the optical members serving as adherends, there are members having ultraviolet shielding properties. However, even when irradiating ultraviolet rays through such ultraviolet ray-shielding members that are difficult to transmit ultraviolet rays, if it is the above-mentioned phosphine oxide-based photoinitiator, the curing of the active energy ray-curable component (C) can proceed.

[0105] The content of the photoinitiator (D) in the pressure-sensitive adhesive composition P is preferably 1 to 30 parts by mass, more preferably 4 to 22 parts by mass, and even more preferably 8 to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (C). Thereby, the obtained pressure-sensitive adhesive sheet is likely to satisfy desired physical properties and is likely to be excellent in unevenness followability and blister resistance. In particular, in the vicinity of the unevenness, while following the unevenness well, optical unevenness is suppressed.

[0106] (2.4.5. Coloring component (E)) In the present embodiment, it is preferable that at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contains the coloring component (E). When a plurality of layers contain the coloring component (E), the coloring components may be the same or different. By including the coloring component (E), the total light transmittance and haze value of the pressure-sensitive adhesive layer can be adjusted to a desired range, and the designability of the display body to which the pressure-sensitive adhesive layer is bonded can be enhanced. When the pressure-sensitive adhesive layer is one layer, it is preferable that the pressure-sensitive adhesive layer contains the coloring component (E). When the pressure-sensitive adhesive layer is composed of three or more layers, it is preferable that at least one layer contains the coloring component (E).

[0107] The coloring component (E) may be a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. From the viewpoint of the durability of the resulting adhesive, an inorganic pigment is preferred. The color of the coloring component (E) can be appropriately selected according to the purpose, but generally, it is preferably a dark or intense color such as black, brown, navy, purple, blue, etc., and black is particularly preferred.

[0108] Examples of the inorganic pigment include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, ATO (antimony tin oxide)-based pigments, etc.

[0109] Examples of the organic pigment and the organic dye include ammonium-based pigments, cyanine-based pigments, merocyanine-based pigments, croconium-based pigments, squarium-based pigments, azulenium-based pigments, polymethine-based pigments, naphthoquinone-based pigments, pyrylium-based pigments, phthalocyanine-based pigments, naphthalocyanine-based pigments, naphtholactam-based pigments, azo-based pigments, condensed azo-based pigments, indigo-based pigments, perinone-based pigments, perylene-based pigments, dioxazine-based pigments, quinacridone-based pigments, isoindolinone-based pigments, quinophthalone-based pigments, pyrrole-based pigments, thioindigo-based pigments, metal complex-based pigments (metal complex dyes), dithiol metal complex-based pigments, indole phenol-based pigments, triallylmethane-based pigments, anthraquinone-based pigments, dioxazine-based pigments, naphthol-based pigments, azomethine-based pigments, benzimidazolone-based pigments, pyranthrone-based pigments, and threne-based colors, etc.

[0110] Examples of the black pigment include carbon black, copper oxide, iron sesquioxide, manganese dioxide, aniline black, activated carbon, etc. Examples of the black dye include high-concentration vegetable dyes, azo-based dyes, etc.

[0111] The above pigments or dyes can be appropriately mixed and used so as to obtain the desired physical properties in the adhesive layer.

[0112] Among the above coloring components (E), from the viewpoint of easily satisfying the above-described physical properties and enhancing the design property of the display body, carbon black, nigrosine-based black dyes, and chromate-based black dyes are preferable. Note that the carbon black may or may not be subjected to a predetermined treatment (for example, a solvent-loving treatment) on its surface.

[0113] Also, from the viewpoint of optical properties, the above coloring component (E) preferably satisfies the following characteristics.

[0114] The coloring component (E) preferably has an average haze, which is the average value of the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm of a solution obtained by diluting the coloring component 10,000 times with ethyl acetate, in the range of 1 to 60%, more preferably 2 to 40%, still more preferably 3 to 20%, and particularly preferably 4 to 10%. By using such a coloring component (E) in an appropriate amount, it becomes easier to satisfy the above-described optical physical properties (total light transmittance, haze value, etc.) of the adhesive layer.

[0115] Also, the coloring component (E) preferably has a difference value between the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm of a solution obtained by diluting the coloring component 10,000 times with ethyl acetate in the range of 0 to 30 points, more preferably 0.1 to 22 points, particularly preferably 0.5 to 14 points, and still more preferably 1 to 8 points. By using such a coloring component in an appropriate amount, it becomes easier to satisfy the above-described optical physical properties (total light transmittance, haze value, etc.) of the adhesive layer.

[0116] The haze value at a wavelength of 780 nm of a solution obtained by diluting the coloring component (E) 10,000-fold with ethyl acetate is preferably from 0.1 to 50%, more preferably from 0.5 to 35%, particularly preferably from 1 to 20%, and still more preferably from 2 to 10%. Further, the haze value at a wavelength of 380 nm of a solution obtained by diluting the coloring component 10,000-fold with ethyl acetate is preferably from 1 to 60%, more preferably from 3 to 45%, particularly preferably from 6 to 30%, and still more preferably from 10 to 20%. This makes it easier to satisfy the optical physical properties (total light transmittance, haze value, etc.) of the pressure-sensitive adhesive layer.

[0117] Furthermore, the standard deviation of the haze values at each wavelength (i.e., 380 nm, 385 nm, 390 nm, ···, 775 nm, 780 nm) with a 5-nm pitch in the wavelength region of 380 nm to 780 nm of a solution obtained by diluting the coloring component (E) 10,000-fold with ethyl acetate is preferably from 0.1 to 10, more preferably from 0.5 to 6, and particularly preferably from 1 to 3. This makes it easier to satisfy the optical physical properties (total light transmittance, haze value, etc.) of the pressure-sensitive adhesive layer described above.

[0118] The content of the coloring component (E) is preferably from 0.01 to 10 parts by mass, more preferably from 0.05 to 5 parts by mass, still more preferably from 0.1 to 1 part by mass, and particularly preferably from 0.2 to 0.5 part by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A). This makes it easier to satisfy the optical physical properties described above and, since the desired adhesive force and cohesive force are maintained, it becomes easier to satisfy the unevenness followability. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0119] (2.4.6. Other Additives) The pressure-sensitive adhesive composition P may contain other additives as necessary. Examples of such additives include silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, rust preventives, infrared absorbers, softeners, fillers, refractive index modifiers, and the like. Note that the polymerization solvent and dilution solvent described later are not included in the additives constituting the pressure-sensitive adhesive composition P.

[0120] (2.5. Other Constituents of the Adhesive Layer) As shown in FIG. 1A, when the adhesive layer 10 is composed of a single layer, the pressure-sensitive adhesive constituting the adhesive layer 10 may be formed using the above-described pressure-sensitive adhesive composition P. Further, as a method for making the A-side unevenness followability and the B-side unevenness followability different, for example, a method of forming an inclined structure in which the hardness of the pressure-sensitive adhesive changes in the thickness direction from the A-side to the B-side is exemplified.

[0121] Further, as a case where the adhesive layer is composed of two layers, as shown in FIG. 1B, the configuration in which the first adhesive layer and the second adhesive layer are in contact has been described, but a configuration in which the first adhesive layer and the second adhesive layer are not in contact may also be used. Examples of such a configuration include a configuration in which the first adhesive layer and the second adhesive layer are laminated via a member having no adhesiveness. Specifically, a configuration in which a first adhesive layer is formed on one main surface of a base material composed of a resin film or the like and a second adhesive layer is formed on the other main surface is exemplified.

[0122] When the adhesive layer is composed of three or more layers, each layer of the pressure-sensitive adhesive constituting the adhesive layer may be formed using the above-described pressure-sensitive adhesive composition P so that the entire adhesive layer satisfies the above-described physical properties.

[0123] (2.6. Release Sheet) The release sheets 21 and 22 protect the adhesive layer 10 until the adhesive sheet 1 is used and are peeled off when the adhesive sheet 1 is used. In the adhesive sheet 1 according to the present embodiment, one or both of the release sheets 21 and 22 are not necessarily required.

[0124] Examples of the release sheet include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, an ethylene-(meth)acrylic acid copolymer film, an ethylene-(meth)acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, and the like. Further, crosslinked films of these may also be used. Furthermore, laminated films of these may also be used. From the perspective of SDGs, as the material constituting the release sheet, a material with a high biomass content may be used, a material that can be recycled or reused may be used, or a recycled or reused material may be used.

[0125] It is preferable that the release surface of the release sheet (particularly the surface in contact with the pressure-sensitive adhesive layer) is subjected to a release treatment. Examples of the release agent used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Among the release sheets, it is preferable that one release sheet is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force.

[0126] There is no particular limitation on the thickness of the release sheet, but it is usually about 20 to 150 μm.

[0127] (3. Production of the pressure-sensitive adhesive composition) The pressure-sensitive adhesive composition P can be produced, for example, by first producing a (meth)acrylate polymer (A) and then mixing the obtained (meth)acrylate polymer (A) with a crosslinking agent (B). If necessary, it can be produced by mixing an active energy ray curable component (C), a photopolymerization initiator (D), and a coloring component (E).

[0128] (Meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of (meth)acrylic acid ester polymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc., and two or more of them may be used in combination. Examples of the polymerization initiator include azo compounds, organic peroxides, etc., and two or more of them may be used in combination. In the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

[0129] Once the (meth)acrylic acid ester polymer (A) is obtained, a crosslinking agent (B), and if necessary, an active energy ray curable component (C), a photopolymerization initiator (D), a coloring component (E), other additives, a diluting solvent, etc. are added to the solution of the (meth)acrylic acid ester polymer (A) and thoroughly mixed to obtain a pressure-sensitive adhesive composition P (coating solution) diluted with a solvent. In the case where any of the above components is in a solid state, or precipitation occurs when mixed with other components in an undiluted state, the component may be dissolved or diluted in a diluting solvent alone in advance and then mixed with other components.

[0130] Examples of the diluting solvent used include aliphatic hydrocarbons such as hexane, heptane, cyclohexane, aromatic hydrocarbons such as toluene, xylene, halogenated hydrocarbons such as methylene chloride, ethylene chloride, alcohols such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone, esters such as ethyl acetate, butyl acetate, and cellosolve solvents such as ethyl cellosolve.

[0131] The concentration and viscosity of the coating solution prepared in this way may be within the coatable range, without particular limitation, and can be appropriately selected according to the situation. For example, it is diluted so that the concentration of the pressure-sensitive adhesive composition P is 10 to 60% by mass. In addition, when obtaining the coating solution, the addition of a diluting solvent or the like is not a necessary condition. If the pressure-sensitive adhesive composition P has a viscosity or the like that allows coating, it is not necessary to add a diluting solvent. In this case, the pressure-sensitive adhesive composition P becomes a coating solution using the polymerization solvent of the (meth)acrylate polymer (A) as the diluting solvent as it is.

[0132] (4. Manufacture of Adhesive) The adhesive constituting the adhesive layer is preferably obtained by crosslinking the above-described pressure-sensitive adhesive composition P. The crosslinking of the pressure-sensitive adhesive composition P can usually be carried out by heat treatment. In addition, this heat treatment can also be combined with the drying treatment for volatilizing the diluting solvent or the like from the coating film of the pressure-sensitive adhesive composition P applied to the desired object. Further, such an adhesive layer can also be preferably formed by applying the pressure-sensitive adhesive composition P to a desired object, performing heat treatment, and then curing the pressure-sensitive adhesive composition P by irradiation with active energy rays.

[0133] In the case of the pressure-sensitive adhesive composition P, the heating temperature of the heat treatment is preferably 50 to 150°C, more preferably 70 to 120°C. Further, in the case of the pressure-sensitive adhesive composition P, the heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

[0134] Here, the active energy rays refer to those having energy quanta among electromagnetic waves or charged particle beams, and specifically include ultraviolet rays, electron beams, and the like. Among the active energy rays, ultraviolet rays that are easy to handle are particularly preferable. Irradiation with ultraviolet rays can be carried out using a high-pressure mercury lamp, an H lamp manufactured by Heraeus, a xenon lamp, or the like.

[0135] When the pressure-sensitive adhesive composition P is cured by irradiation with active energy rays after heat treatment, the irradiation amount of ultraviolet rays is such that the illuminance is 50 to 1000 mW / cm 2It is preferably at such a level. Also, the light quantity is preferably 50 to 10,000 mJ / cm 2 and more preferably 80 to 5,000 mJ / cm 2 and particularly preferably 200 to 2,000 mJ / cm 2 On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation dose of the electron beam is preferably about 10 to 1,000 krad.

[0136] If necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23°C, relative humidity 50%). When curing is necessary, an adhesive having a crosslinked structure can be obtained after the curing period has elapsed. When curing is not required, an adhesive having a crosslinked structure can be obtained after the heat treatment is completed.

[0137] (5. Manufacture of the adhesive sheet) The method for manufacturing the adhesive sheet is not particularly limited, and it may be manufactured by a known method. For example, a coating solution of the above-described adhesive composition P is applied to the release surface of one release sheet, and heat treatment is performed to crosslink the adhesive composition P to form a coating layer having a predetermined thickness. The release surface of the other release sheet is superposed on the formed coating layer. When curing is necessary, the coating layer becomes an adhesive layer after a predetermined curing period has elapsed. Also, when curing is not required, the coating layer directly becomes the adhesive layer. Thereby, an adhesive sheet is obtained.

[0138] Also, when there are two adhesive layers, for example, a coating solution of an adhesive composition P for forming one adhesive layer (for example, the first adhesive layer) is applied to the release surface of one release sheet, heat treatment is performed to crosslink the adhesive composition, a coating layer is formed, and a release sheet with a coating layer is obtained. Further, a coating solution of an adhesive composition P for forming another adhesive layer (for example, the second adhesive layer) is applied to the release surface of the other release sheet, heat treatment is performed to crosslink the adhesive composition, a coating layer is formed, and a release sheet with a coating layer is obtained. Then, the release sheet with a coating layer and the release sheet with a coating layer are bonded together so that both coating layers are in contact with each other.

[0139] When there are three or more adhesive layers, a plurality of release sheets with coating layers may be produced, and the coating layers may be laminated in a desired number and in a desired lamination order.

[0140] When curing is required, after a predetermined curing period, the coating layer becomes an adhesive layer. Also, when curing is not required, the coating layer remains as the adhesive layer. Further, when the adhesive layer is curable by active energy rays, the adhesive layer may be irradiated with active energy rays as needed to cure the adhesive layer. Through the above steps, the adhesive sheet 1 is obtained.

[0141] Examples of the method for applying the coating liquid of the pressure-sensitive adhesive composition P include a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, and the like.

[0142] (6. Use of the Adhesive Sheet) The adhesive sheet according to this embodiment is used as follows. First, one release sheet is removed from the adhesive sheet, and the exposed adhesive layer is bonded to the first member (or the second member). Subsequently, the other release sheet is peeled off, and the exposed adhesive layer is bonded to the second member. Thereby, a laminate in which the first member and the second member are laminated and integrated via the adhesive layer is obtained.

[0143] Also, when the adhesive layer is curable by active energy rays, if necessary, the adhesive layer of the obtained laminate may be irradiated with a predetermined active energy ray to cure the adhesive layer to form a cured adhesive layer.

[0144] When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains an active energy ray curable component, before irradiating the active energy ray, since the pressure-sensitive adhesive layer is bonded to the first member or the second member, the pressure-sensitive adhesive layer is relatively soft while containing a crosslinked structure, and even if irregularities are formed on the first member and / or the second member, it sufficiently follows the irregularities, and it is possible to suppress the occurrence of gaps, floating, etc. in the vicinity of the irregularities.

[0145] After the adhesive layer is bonded to the optical member in a relatively soft state, the adhesive layer is irradiated with predetermined active energy rays to cure the adhesive layer. Therefore, the cohesive force of the cured adhesive layer can be increased in a state where the unevenness followability is good, so that both the unevenness followability and the blister resistance can be achieved. In particular, in the vicinity of the unevenness, optical unevenness is suppressed while following the unevenness well.

[0146] (7. Laminated body) As shown in FIG. 2, the laminated body 3 according to the present embodiment includes a first member 31 (one display body constituent member) having unevenness 41, a second member 32 (another display body constituent member), and an adhesive layer 10 that is located between them and bonds the first member 31 and the second member 32 to each other.

[0147] Since the adhesive layer 10 in the laminated body 3 is the adhesive layer 10 or the cured adhesive layer of the above-described adhesive sheet 1, it is bonded while sufficiently following the unevenness 41. Therefore, the unevenness followability and the blister resistance are good. Also, optical unevenness is suppressed even in the vicinity of the unevenness.

[0148] The laminated body 3 is preferably the display body itself or a member constituting a part of the display body. Examples of the display body include in-vehicle display bodies in automotive instrument panels, car navigation systems, various instruments provided on consoles, etc., display bodies for general users such as smartphones and tablet terminals, display bodies for commercial tablet terminals and digital signage, and display bodies for outdoor digital signage. Examples of the type of display body include an organic electroluminescence (organic EL) display, an electrophoretic display (electronic paper), a liquid crystal display using a plastic substrate (film) as a substrate, and a light-emitting diode (LED) display. These may be touch panels provided with position input means.

[0149] These display bodies may also be flexible displays. The flexible display may be a display including a member that is bent once during manufacturing and maintains the bent state, or a display including a member that can be repeatedly bent (including folding). Examples of the flexible display include a foldable display, a rollable display, a stretchable display, and the like.

[0150] When the laminate 3 is the display body itself or a member (display body component) constituting a part of the display body, the unevenness 41 in the laminate 3 may be the unevenness of the display body component itself, or the unevenness caused by other components formed in the display body component. Examples of the unevenness caused by such other components include steps caused by a printing layer, steps caused by a light-emitting body, and the like.

[0151] When the unevenness is a step caused by a printing layer, the display body component on which the printing layer is formed is exemplified by a protective panel made of a glass plate, a plastic plate, or a laminate including them. The printing layer is generally formed in a frame shape on the protective panel. The material constituting the printing layer is not particularly limited, and known materials for printing are used. The thickness of the printing layer, that is, the height of the step, is preferably 3 to 40 μm, more preferably 5 to 35 μm, still more preferably 7 to 30 μm, and even more preferably 10 to 25 μm. Thereby, the adhesive layer can sufficiently follow the step.

[0152] The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, and the like. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

[0153] The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

[0154] In addition, various functional layers (such as a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an optical adjustment layer, an ultraviolet absorption layer, and a writing quality improvement layer) may be provided on one or both sides of the glass plate or the plastic plate, or an optical member may be laminated. Further, the transparent conductive film and the metal layer may be patterned.

[0155] The display body component is preferably an optical member, a display body module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, an electrophoretic display, etc.), an optical member as a part of the display body module, or a laminate including the display body module. Examples of the optical member include an anti-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, a transflective film, and a transparent conductive film. Examples of the anti-scattering film include a hard coat film formed by forming a hard coat layer on one side of a base film.

[0156] When the unevenness is a step caused by the light emitter, examples of the display body component on which the light emitter is formed include a substrate provided with the light emitter. Such a substrate may be a direct-lit backlight. For example, the backlight of a liquid crystal display is exemplified. Examples of the light emitter include a light emitting diode (LED), a laser diode (LD), an organic electroluminescence light emitting element, and an inorganic electroluminescence light emitting element. Among these, from the viewpoint of the sealing property by the adhesive layer, an LED is preferable, and particularly, a mini LED or a micro LED is preferable.

[0157] The thickness of the light-emitting body is preferably 10 to 300 μm, more preferably 30 to 200 μm, still more preferably 50 to 150 μm, and particularly preferably 80 to 120 μm. When a plurality of light-emitting bodies are provided, the width of the gap between adjacent light-emitting bodies is preferably 0.01 to 100 mm, more preferably 0.1 to 10 mm, and still more preferably 0.5 to 4 mm. The shape of the light-emitting body is not particularly limited, but is usually a rectangular parallelepiped shape, a hemispherical shape, or the like. The size of the light-emitting body is not particularly limited, but from the viewpoint of the light-emitting body sealing property, one side or the diameter in a plan view is preferably 0.01 to 100 mm, and more preferably 0.1 to 10 mm.

[0158] An example of manufacturing the laminate 3 is shown. First, one release sheet 21 of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 10 of the adhesive sheet 1 is bonded to one surface of the first member 31.

[0159] Thereafter, the other release sheet 22 is peeled off from the adhesive layer 10 of the adhesive sheet 1, and the exposed adhesive layer 10 of the adhesive sheet 1 and the second member 32 are bonded together to obtain the laminate 3. As another example, the bonding order of the first member 31 and the second member 32 may be reversed.

[0160] When the adhesive layer 10 is curable by active energy rays, if necessary, after bonding the adhesive layer 10, the first member 31, and the second member 32, active energy rays are irradiated to the adhesive layer 10. Thereby, the active energy ray curable component (C) in the adhesive layer 10 is polymerized, and the laminate 3 in which the adhesive layer 10 is cured is obtained.

[0161] (8. Display body) The display body according to this embodiment includes the above-described laminate, and may consist only of the laminate, or may be configured to include one or more laminates and other members. When laminating one laminate and another laminate, or when laminating a laminate and other members, it is preferable to laminate them through the adhesive layer of the above-described adhesive sheet. Therefore, the display body according to this embodiment is excellent in unevenness followability, blister resistance, and design, and moreover, optical unevenness is suppressed.

[0162] In addition, in this specification, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also the meaning of "preferably larger than X" or "preferably smaller than Y". Further, when described as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably larger than X", and when described as "Y or less" (Y is an arbitrary number), unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

[0163] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments at all, and may be modified in various ways within the scope of the present invention.

[0164] (Production Example 1) 1. Preparation of (meth)acrylate polymer 25 parts by mass of n-butyl acrylate, 30 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of N-acryloylmorpholine, 10 parts by mass of isobornyl acrylate, 5 parts by mass of methyl methacrylate, and 25 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylate polymer (A). When the molecular weight of the obtained (meth)acrylate polymer (A) was measured by the method shown below, the weight average molecular weight (Mw) was 500,000.

[0165] The weight average molecular weight (Mw) is the weight average molecular weight in terms of polystyrene measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement). (Measurement Conditions) ·GPC measuring device: manufactured by Tosoh Corporation, HLC-8020 ·GPC column (passing in the following order): manufactured by Tosoh Corporation TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL ·Measurement solvent: tetrahydrofuran ·Measurement temperature: 40 °C

[0166] 2. Preparation of the pressure-sensitive adhesive composition 100 parts by mass of the (meth)acrylate copolymer (A) obtained above (in terms of solid content; the same shall apply hereinafter), 0.2 part by mass of an isocyanate-based crosslinking agent as the crosslinking agent (B) (manufactured by Mitsui Chemicals, product name "Takenate D-101E", isocyanate type: tolylene diisocyanate, modified form: trimethylolpropane adduct), and 0.25 part by mass of a black pigment as the coloring component (E) were mixed, stirred well, and diluted with methyl ethyl ketone to obtain a coating solution of the pressure-sensitive adhesive composition.

[0167] 3. Manufacture of the pressure-sensitive adhesive layer The obtained coating solution of the pressure-sensitive adhesive composition was applied with a knife coater to the release-treated surface of a release sheet obtained by subjecting one side of a polyethylene terephthalate film to a release treatment with a silicone-based release agent. Then, the coating layer was heat-treated at 90 °C for 1 minute to allow the crosslinking reaction to proceed, thereby forming a coating layer.

[0168] Next, the coating layer on the release sheet obtained above was laminated to the release-treated surface of a release sheet obtained by subjecting one side of a polyethylene terephthalate film to a release treatment with a silicone-based release agent so that the coating layer was in contact therewith, and cured for 7 days under the conditions of 23 °C and a relative humidity of 50% to produce a pressure-sensitive adhesive layer (non-curable by active energy rays) having a thickness of 25 μm.

[0169] The thickness of the pressure-sensitive adhesive layer is a value measured using a constant-pressure thickness measuring instrument (PG-02 manufactured by Teclock Corporation) in accordance with JIS K7130.

[0170] (Production Examples 2 to 7) The pressure-sensitive adhesive layer was produced in the same manner as in Production Example 1, except that the composition of the (meth)acrylic acid ester polymer (A), the type and blending amount of the crosslinking agent (B), the type and blending amount of the active energy ray curable component (C), the type and blending amount of the photopolymerization initiator (D), the blending amount of the coloring component (E), and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. For Production Examples 4 and 5, the coating layer was irradiated with active energy rays (ultraviolet rays; UV) through the release sheet for curing. The irradiation conditions of the active energy rays are shown below. Also, for the dyed PET film, for convenience, it is shown in Table 1. <Irradiation conditions of active energy rays (hereinafter referred to as "Condition A")> ·Using a high-pressure mercury lamp ·Illuminance 200 mW / cm 2 , light quantity 2000 mJ / cm 2 ·As the UV illuminance and light quantity meter, "UVPF-A1" manufactured by Aigraphics Co., Ltd. was used

[0171] In Table 1, the blending amounts of the crosslinking agent (B), the active energy ray curable component (C), the photopolymerization initiator (D), and the coloring component (E) were amounts (in terms of solid content) relative to 100 parts by mass (in terms of solid content) of the (meth)acrylic acid ester polymer (A). Also, the pressure-sensitive adhesives of Production Examples 1, 4, 5, and 7 were non-curable by active energy rays, and the pressure-sensitive adhesives of Production Examples 2, 3, and 6 were curable by active energy rays.

[0172]

Table 1

[0173] Details of the abbreviations and the like described in Table 1 are as follows. Regarding the coloring component (E), Table 2 shows the optical properties of a solution obtained by diluting the coloring component E1 described in Table 1 10,000-fold with ethyl acetate. The optical properties shown in Table 2 were calculated from the haze value (%) obtained using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000 for the above dilution solution. The difference from the haze value is the difference between the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm, the average haze is the average value of the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm, and the standard deviation of the haze value is the standard deviation of the haze values at each wavelength with a 5 nm pitch in the wavelength region of 380 nm to 780 nm. ((Meth)acrylate polymer (A)) BA: n-Butyl acrylate 2EHA: 2-Ethylhexyl acrylate ACMO: N-Acryloylmorpholine IBXA: Isobornyl acrylate MMA: Methyl methacrylate HEA: 2-Hydroxyethyl acrylate 4HBA: 4-Hydroxybutyl acrylate AAc: Acrylic acid (Crosslinking agent (B)) B1: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E", isocyanate type: tolylene diisocyanate, modified form: trimethylolpropane adduct) B2: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-110N", isocyanate type: xylylene diisocyanate, modified form: trimethylolpropane adduct) (Active energy ray curable component (C)) C1: ε-Caprolactone-modified tris-(2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300-1CL") C2: Tris-(2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300") (Photoinitiator (D)) D1: 2,4,6-Trimethylbenzoyl diphenyl phosphine oxide D2: A mixture of 1-hydroxycyclohexyl phenyl ketone and benzophenone in a mass ratio of 1:1 (Coloring component (E)) E1: Carbon black-based black pigment

[0174]

Table 2

[0175] (Measurement of total light transmittance) The adhesive layers obtained in Production Examples 1 to 7 were bonded to glass to obtain measurement samples. After performing background measurement with glass, the total light transmittance (%) of the above measurement samples was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7361-1:1997. The results are shown in Table 3. For Production Examples 2, 3, and 6, the total light transmittance before and after irradiation with active energy rays (ultraviolet rays; UV) was measured by the same method as above. The irradiation conditions of the active energy rays were the above Condition A.

[0176] (Measurement of haze value) For the adhesive layers obtained in Production Examples 1 to 7, the haze value (%) was measured from the adhesive layer side using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000. The obtained haze values (%) are shown in Table 3. For Production Examples 2, 3, and 6, the haze values before and after irradiation with active energy rays (ultraviolet rays; UV) were measured by the same method as above. The irradiation conditions of the active energy rays were the above Condition A.

[0177] (Measurement of adhesive strength of adhesive layer) The release sheet was peeled off from the pressure-sensitive adhesive layers obtained in Production Examples 1 to 7, and the exposed pressure-sensitive adhesive layers were laminated onto the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4160", thickness: 100 μm) having an easy-adhesion layer to obtain a laminate of release sheet / pressure-sensitive adhesive layer / PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

[0178] In an environment of 23°C and a relative humidity of 50%, the release sheet was peeled off from the above sample, and the exposed pressure-sensitive adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). Then, it was pressurized at 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. Thereafter, after leaving it to stand for 24 hours under the conditions of 23°C and a relative humidity of 50%, using a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon"), the adhesive strength (N / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. The measurement was carried out in accordance with JIS Z0237:2009 except for the conditions described here. The results are shown in Table 3. For Production Examples 2, 3, and 6, the adhesive strength before and after irradiation with active energy rays (ultraviolet rays; UV) was measured by the same method as above. The active energy ray irradiation conditions were the above Condition A.

[0179] (Storage elastic modulus of the pressure-sensitive adhesive layer) The pressure-sensitive adhesive layers obtained in Production Examples 1 to 7 were laminated in a plurality of layers to form a laminate with a thickness of 3 mm. From the obtained laminate of the pressure-sensitive adhesive layer, a cylinder with a diameter of 8 mm (height: 3 mm) was punched out and used as a sample for measuring the storage elastic modulus.

[0180] Regarding the measurement sample, in accordance with JIS K7244-6, using a viscoelasticity measuring device (MCR301 manufactured by Anton Paar), the storage elastic modulus was measured by the torsional shear method under the conditions of a measurement temperature of 25°C and a measurement frequency of 1 Hz. The results are shown in Table 3. For Production Examples 2, 3, and 6, the storage elastic modulus before and after irradiation with active energy rays (ultraviolet rays; UV) was measured by the same method as above. The active energy ray irradiation conditions were the above Condition A.

[0181] (Evaluation of the gel fraction of the pressure-sensitive adhesive) The pressure-sensitive adhesive layers obtained in Production Examples 1 to 7 were cut into a size of 80 mm × 80 mm, and the colored pressure-sensitive adhesive layers were wrapped with a polyester mesh (product name: Tetoron Mesh #200), and their masses were weighed using an analytical balance. By subtracting the mass of the above mesh alone from the weighed value, the mass of only the pressure-sensitive adhesive was calculated. The mass at this time was designated as M1.

[0182] Next, the pressure-sensitive adhesive wrapped with the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Then, the mesh was taken out and air-dried for 24 hours in an environment at a temperature of 23°C and a relative humidity of 50%, and further dried in an oven at 80°C for 12 hours. After drying, its mass was weighed using an analytical balance. By subtracting the mass of the above mesh alone from the weighed value, the mass of only the pressure-sensitive adhesive was calculated. The mass at this time was designated as M2. Using the obtained M1 and M2, the gel fraction was calculated from the following formula. The results are shown in Table 3. Gel fraction (%) = (M2 / M1) × 100 Regarding Production Examples 2, 3, and 6, in the same manner as the measurement of the total light transmittance, the gel fractions before and after irradiation with active energy rays (ultraviolet rays; UV) were measured by the same method as above. The active energy ray irradiation conditions were the above Condition A.

[0183] [Table 3]

[0184] (Example 1) Two pressure-sensitive adhesive layers obtained in Production Example 2 were laminated to form a first pressure-sensitive adhesive layer with a thickness of 50 μm. Subsequently, six pressure-sensitive adhesive layers obtained in Production Example 6 were laminated to form a second pressure-sensitive adhesive layer with a thickness of 150 μm. The main surface of the obtained first pressure-sensitive adhesive layer and the main surface of the second pressure-sensitive adhesive layer were bonded together to obtain a pressure-sensitive adhesive sheet having the configuration shown in Table 4.

[0185] (Examples 2 to 5 and Comparative Examples 1 to 3) The pressure-sensitive adhesive layers of Production Examples 1 to 7 were selected so that the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer would have the combinations shown in Table 4, and they were laminated to have the thicknesses shown in Table 4 to obtain a pressure-sensitive adhesive sheet. In Example 5, the pressure-sensitive adhesive layer had three layers. Further, in Comparative Example 3, the pressure-sensitive adhesive layer of Production Example 3 was formed on both main surfaces of a dyed PET film (dyed PET). For the dyed PET, the thickness is shown in Table 1, and the storage elastic modulus, total light transmittance, haze, and gel fraction are shown in Table 3 for convenience.

[0186]

Table 4

[0187] (Conformability) Ultraviolet curable ink (manufactured by Teikoku Ink Co., Ltd., product name "POS-911 Ink") was screen-printed in a frame shape (outer shape: 90 mm in length × 50 mm in width, 5 mm in width) on the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning Glass Eagle XG", 90 mm in length × 50 mm in width × 0.5 mm in thickness). Next, ultraviolet rays were irradiated (80 W / cm 2 , two metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m / min) to cure the printed ultraviolet curable ink, and a stepped glass plate having a step (step height: any one of 5 μm, 10 μm, 15 μm, 20 μm, and 25 μm) due to printing was produced.

[0188] From the pressure-sensitive adhesive sheets produced in the examples and comparative examples, the release sheet was peeled off so that the main surface of the second pressure-sensitive adhesive layer was exposed. The exposed second pressure-sensitive adhesive layer was bonded to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4160", thickness: 100 μm) having an easy-adhesion layer. Next, the other release sheet was peeled off to expose the main surface (A surface) of the first pressure-sensitive adhesive layer. Then, using a laminator (manufactured by Fujiplas Co., Ltd., product name "LPD3214"), the pressure-sensitive adhesive layer was laminated to each stepped glass plate so that the main surface (A surface) of the first pressure-sensitive adhesive layer covered the entire printed surface in a frame shape, and this was used as a sample for evaluation.

[0189] The obtained evaluation sample was subjected to autoclave treatment at 50 °C and 0.5 MPa for 30 minutes, and then left standing for 24 hours at normal pressure, 23 °C, and a relative humidity of 50%. For the pressure-sensitive adhesive sheets prepared in Examples 1 and 3 and Comparative Examples 1 to 3, active energy rays were irradiated under the above Condition A through the PET film to cure the pressure-sensitive adhesive layer.

[0190] Next, it was stored for 72 hours under high-temperature and high-humidity conditions of 85 °C and a relative humidity of 85% (durability test), and then the unevenness followability of the A side was evaluated. The unevenness followability was judged by whether the printing step was completely filled by the pressure-sensitive adhesive layer. When bubbles, lifting, peeling, etc. were observed at the interface between the printing step and the pressure-sensitive adhesive layer, it was judged that the unevenness of the printing step could not be followed. Here, the unevenness followability was evaluated as the unevenness followability rate (%) shown by the following formula. The results are shown in Table 5. Unevenness followability rate (%) = {(height of the step (μm) where the state of being filled without bubbles, lifting, peeling, etc. was maintained after the durability test) / (thickness of the pressure-sensitive adhesive layer)} × 100

[0191] Also, in the same manner as above, the unevenness followability of the B side was evaluated. The results are shown in Table 5. Further, from the obtained A-side unevenness followability rate and B-side unevenness followability rate, the difference in the unevenness followability rate (A-side unevenness followability rate - B-side unevenness followability rate) was calculated. The results are shown in Table 5.

[0192] (Total light transmittance) For the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets prepared in the examples and comparative examples, the total light transmittance was measured in the same manner as the above measurement of the total light transmittance. The results are shown in Table 5. For the pressure-sensitive adhesive sheets prepared in Examples 1 and 3 and Comparative Examples 1 to 3, active energy rays were irradiated under the above Condition A through the PET film to cure the pressure-sensitive adhesive layer.

[0193] (Haze value) For the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets prepared in the examples and comparative examples, the total light transmittance was measured in the same manner as the measurement of the total light transmittance described above. The results are shown in Table 5. For the pressure-sensitive adhesive sheets prepared in Examples 1 and 3 and Comparative Examples 1 to 3, the active energy rays were irradiated through the PET film under the above Condition A to cure the pressure-sensitive adhesive layer.

[0194] (Ratio of storage elastic modulus of colored pressure-sensitive adhesive layer to storage elastic modulus of transparent pressure-sensitive adhesive layer) In the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets prepared in the examples and comparative examples, the ratio of the storage elastic modulus (G1b') of the colored pressure-sensitive adhesive layer (pressure-sensitive adhesive layer containing carbon black) to the storage elastic modulus (G2b') of the transparent pressure-sensitive adhesive layer (pressure-sensitive adhesive layer not containing carbon black) was calculated. The results are shown in Table 5. For the pressure-sensitive adhesive sheets prepared in Examples 1 and 3 and Comparative Examples 1 to 3, the above ratio was also calculated for the storage elastic moduli (G1a' and G2a') after irradiating the active energy rays through the PET film under the above Condition A to cure the pressure-sensitive adhesive layer.

[0195] (Evaluation 1 of unevenness followability and color unevenness) As adherends, a stepped glass (step height: 25 μm) prepared in the same manner as the stepped glass plate prepared in the measurement of the unevenness followability rate and a glass plate without steps (manufactured by NSG Precision, product name "Corning Glass Eagle XG", vertical 90 mm × horizontal 50 mm × thickness 0.5 mm) were prepared. In Table 5, the stepped glass is described as the unevenness plate, and the glass plate without steps is described as the smooth plate.

[0196] The release sheet was peeled off from the pressure-sensitive adhesive sheets prepared in the examples and comparative examples, and the exposed first pressure-sensitive adhesive layer was attached to the smooth plate. Next, the release sheet was peeled off from the pressure-sensitive adhesive sheet, and the exposed second pressure-sensitive adhesive layer was bonded to the unevenness plate.

[0197] With the uneven plate side of the structure obtained in this way facing downwards, it was placed on top of a tablet terminal (manufactured by Apple Inc., product name "iPad (registered trademark)", resolution: 264 ppi). Regarding this sample, the tablet terminal was set to display a full white screen, and the vicinity of the step was visually observed to evaluate the unevenness followability according to the following criteria. The results are shown in Table 5. ○... No lifting or peeling ×... Lifting or peeling occurred

[0198] Furthermore, the vicinity of the step was visually observed to evaluate color unevenness according to the following criteria. The results are shown in Table 5. ◎: Color unevenness cannot be visually recognized either from an angle of 60 degrees obliquely or from the front. ○: Color unevenness can be visually recognized when viewed from an angle of 60 degrees obliquely, but not when viewed from the front. ×: Color unevenness can be visually recognized from the front.

[0199] (Evaluation of unevenness followability and color unevenness 2) The unevenness followability and color unevenness were evaluated in the same manner as above, except that the second adhesive layer was attached to the uneven plate and then the first adhesive layer was attached to the smooth plate. The results are shown in Table 5.

[0200] (Evaluation of blister resistance) The release sheet was peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was attached to an ITO-deposited film (manufactured by Oike Kogyo Co., Ltd., product name "Tetrite TCFKH150NMH2 - 125 - U6 / T2"). Furthermore, the release sheet was peeled off from the adhesive sheet, and the exposed adhesive layer was attached to the polycarbonate side of a resin plate (manufactured by Mitsubishi Gas Chemical Company, Inc., product name "Iupilon Sheet MR58U", containing an ultraviolet absorber, thickness: 1 mm) in which a polymethyl methacrylate resin layer was laminated on a polycarbonate resin plate, thereby obtaining an evaluation sample. For the adhesive sheets manufactured in Examples 1, 3 and Comparative Examples 1 - 3, the adhesive layer was irradiated with active energy rays under the same conditions as in Production Example 1 through a plastic plate to cure the adhesive layer.

[0201] Thereafter, the evaluation sample was autoclaved at 50°C and 0.5 MPa for 20 minutes, left standing at normal pressure, 23°C, and 50% relative humidity for 12 hours, and then stored under high-temperature and high-humidity conditions of 85°C and 85% relative humidity for 72 hours. Thereafter, the state at the interface between the adhesive layer and the adherend was visually confirmed, and the blister resistance was evaluated according to the following criteria. The results are shown in Table 5. ◎… No bubbles, lifting, or peeling ○… No lifting or peeling, and although a few bubbles occurred, it was at an acceptable level ×… Lifting or peeling occurred

[0202]

Table 5

[0203] From Table 5, it was confirmed that the adhesive sheets of Examples 1 to 5 can achieve both unevenness followability and blister resistance while suppressing color unevenness caused by unevenness.

Industrial Applicability

[0204] The adhesive sheet of the present invention can be suitably used, for example, for bonding members constituting a display body.

Explanation of Signs

[0205] 1... Adhesive sheet 10... Adhesive layer 11... First adhesive layer 12... Second adhesive layer 10a(11a)... A side 10b(12a)... B side 21, 22... Release sheet 3... Laminate 31... First member 32... Second member

Claims

1. An adhesive sheet having an adhesive layer for bonding a first member and a second member, wherein the adhesive layer is composed of two or more layers including a first adhesive layer having a total light transmittance of 3% or more and 85% or less, and a second adhesive layer having a total light transmittance of more than 85% and 100% or less, when one main surface of the adhesive layer is defined as surface A and the other main surface is defined as surface B, the A-surface unevenness followability (%) indicating the followability of surface A to the unevenness when surface A is bonded to an adherend having unevenness, and the B-surface unevenness followability (%) indicating the followability of surface B to the unevenness when surface B is bonded to an adherend having unevenness, are different, the A-surface unevenness followability is 1 to 7.5%, and the B-surface unevenness followability is 3 to 20%, the value obtained by subtracting the B-surface unevenness followability from the A-surface unevenness followability is -10 points or more and -2 points or less, and the adhesive sheet wherein surface B is the main surface of the second adhesive layer.

2. The adhesive sheet according to claim 1, wherein the adhesive layer contains a coloring component.

3. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer is an acrylic adhesive having a crosslinked structure.

4. A laminate including a first member, a second member, and an adhesive layer for bonding the first member and the second member to each other, wherein at least one of the first member and the second member has unevenness, the adhesive layer is the adhesive layer of the adhesive sheet according to claim 1 or 2, and the second adhesive layer of the adhesive layer is bonded along the unevenness.

5. A display body including the laminate according to claim 4.

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