Adhesive sheet, laminate, and display

Abstract

The present invention is an adhesive sheet having an adhesive layer for bonding a first member and a second member, the adhesive layer containing an adhesive component, a coloring component, and a light diffusion component, and the total light transmittance of the adhesive layer being 5% or more and 95% or less. The adhesive layer may be a single layer or two or more layers. The haze value of the adhesive layer is preferably from 5% to 99.9% (inclusive). Provided is an adhesive sheet capable of providing both seamlessness and concealment of a display body.

Description

Technical Field

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

[0002] A display (display) of a device such as an electronic device is formed by laminating a display member including a liquid crystal element, a light-emitting diode (LED) element, an organic electroluminescent (organic EL) element, and other members (e.g., a protective panel for protecting the display member). This laminate of the display member and other members is typically formed by laminating the display member and other members using an adhesive layer of an adhesive sheet.

[0003] In recent years, in order to improve the design of displays, efforts have been made to make the boundaries between components constituting the display less visible in order to give the display's peripheral components (such as a frame) and the display a sense of unity (seamlessness) when the display is off.

[0004] Patent Document 1 discloses that a colored adhesive layer composed of a colored adhesive is used to control the total light transmittance of the adhesive layer, thereby imparting seamless properties.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-169262 Summary of the Invention

[0008] (1) Technical issues to be resolved

[0009] Such displays are often used as touch panels with position input tools. For example, a patterned transparent conductive film is used in the position input detection component that constitutes the position input tool. This can cause the circuit pattern of the transparent conductive film to be visible from the outside, revealing the transparent conductive film. This visual visibility of the circuit pattern detracts from the appearance of the display and is therefore undesirable. In such cases, even with a colored adhesive layer, as disclosed in Patent Document 1, the circuit pattern cannot be concealed.

[0010] In addition, regarding liquid crystal display devices that are mostly used as displays, since the display portion composed of a liquid crystal panel and the like does not emit light itself, the display device using this display portion is equipped with a backlight element that illuminates the display portion. The configuration method of the light source of the backlight element in such a display device is usually a side-light type in which the light source is configured on the side of the light guide plate, but recently, from the perspective of the brightness and contrast of the screen, research has been conducted on direct-type backlight elements in which the light source is configured directly below the display portion. For example, in order to increase the amount of light in a direct-type backlight element and make the amount of light uniform between the center and the ends of the screen when used as a display device, research has been conducted on arranging multiple light-emitting bodies (typically light-emitting diodes (LEDs)) on a substrate.

[0011] When a display device is manufactured using a backlight element having multiple light emitters as a light source, it is undesirable that the light source arrangement pattern formed by the presence and absence of the light emitters is visually discernible, as this would result in a poor appearance of the display. In such a case, even if a colored adhesive layer such as that disclosed in Patent Document 1 is used, the poor appearance caused by the presence and absence of the light emitters cannot be concealed.

[0012] As described above, it is considered difficult to reliably conceal an internal structure (circuit pattern, light source arrangement pattern, etc.) that should not be visually recognized from the outside.

[0013] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide an adhesive sheet that can achieve both seamlessness and concealment.

[0014] (2) Technical solution

[0015] The scheme of the present invention is as follows.

[0016] [1] An adhesive sheet having an adhesive layer for bonding a first member and a second member,

[0017] The adhesive layer contains an adhesive component, a coloring component and a light diffusion component.

[0018] The total light transmittance of the adhesive layer is 5% or more and 95% or less.

[0019] [2] The adhesive sheet according to [1], wherein the adhesive layer is composed of two or more layers.

[0020] [3] The adhesive sheet according to [1], wherein the adhesive layer is a single layer.

[0021] [4] The adhesive sheet according to any one of [1] to [3], wherein the haze value of the adhesive layer is 5% or more and 99.9% or less.

[0022] [5] The adhesive sheet according to any one of [1] to [4], wherein the light diffusion component is light diffusion particles.

[0023] [6] The adhesive sheet according to any one of [1] to [5], wherein the adhesive component is an acrylic adhesive component.

[0024] [7] A laminate comprising a first member, a second member, and an adhesive layer for bonding the first member and the second member to each other,

[0025] The adhesive layer is an adhesive layer included in the adhesive sheet according to any one of [1] to [6].

[0026] [8] A display comprising the laminate according to [7].

[0027] (3) Beneficial effects

[0028] According to the present invention, it is possible to provide an adhesive sheet that can achieve both seamlessness and concealment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A This is a cross-sectional view of an example of the adhesive sheet according to this embodiment.

[0030] Figure 1B This is a cross-sectional view of another example of the adhesive sheet according to this embodiment.

[0031] Figure 2 It is a cross-sectional view of the laminated body of this embodiment.

[0032] Figure 3 This is a cross-sectional view of an example of the display body of this embodiment.

[0033] Figure 4 This is a cross-sectional view of another example of the display body of this embodiment. DETAILED DESCRIPTION

[0034] The present invention is described in detail below based on specific embodiments.

[0035] (1. Adhesive sheet)

[0036] The adhesive sheet of this embodiment has an adhesive layer. The adhesive layer bonds the first member and the second member together. In this embodiment, the first member and the second member are preferably members constituting a display (display constituting members).

[0037] The display is constructed by stacking display components with specified functions, each of which is bonded together via an adhesive layer. To enhance the design of such a display, the boundaries between the display components are made less visible, and when the display is off, the display frame and the display are given a sense of unity (seamlessness).

[0038] Seamlessness can be easily achieved by, for example, coloring the adhesive layer to control the total light transmittance or brightness of the adhesive layer.

[0039] However, the display body is not only required to be seamless, but also required to be concealed so that the internal structure (circuit pattern, light source arrangement pattern, etc.) should not be visually recognizable from the outside. In particular, when the display body is a touch panel, the so-called bone-seeing phenomenon caused by the circuit pattern sometimes occurs, so good concealment is sought. In addition, when the display body uses a backlight element with multiple light-emitting bodies as a light source, due to the large amount of light, although a high-brightness and high-precision image can be obtained, the light source arrangement pattern formed by the presence area and the non-presence area of ​​the light-emitting body will become easy to visually recognize. Furthermore, the boundary between the components of the display body will also become easy to visually recognize. Therefore, in such a case, good concealment is also sought.

[0040] Such concealment has been addressed by, for example, adjusting the haze value of the adhesive layer, a method previously implemented. However, if the content of the coloring component (e.g., pigment) contained in the adhesive layer increases, the haze value tends to increase, while the total light transmittance tends to decrease. Therefore, if the haze value is controlled by adjusting the content of the coloring component in the adhesive layer to control concealment, the total light transmittance cannot be controlled, and thus good seamlessness cannot be achieved. In other words, controlling the haze value will have a significant impact on the total light transmittance.

[0041] To address the above-mentioned issues, the inventors of this application conducted extensive research and discovered that, in this embodiment, the adhesive layer is configured as the adhesive layer described below. As a result, the adhesive layer of the adhesive sheet of this embodiment can independently control the total light transmittance and haze value. Therefore, a display including this adhesive layer can achieve both seamlessness and concealment.

[0042] (2. Adhesive layer)

[0043] The adhesive layer of the adhesive sheet of this embodiment includes an adhesive component, a coloring component, and a light-diffusing component. The details of the adhesive component, the coloring component, and the light-diffusing component will be described later. In addition, the adhesive layer can be composed of one layer (single layer) or a plurality of layers of two or more layers.

[0044] The thickness of the adhesive layer is preferably 1 to 1000 μm, more preferably 5 to 700 μm, further preferably 10 to 500 μm, particularly preferably 30 to 300 μm, particularly preferably 45 to 200 μm, and most preferably 60 to 120 μm. This facilitates satisfying the optical properties described below while also providing excellent unevenness embedding properties. When the adhesive layer is composed of multiple layers, the aforementioned thickness refers to the total thickness of the multiple layers.

[0045] When the adhesive layer is composed of multiple layers, the thickness of each adhesive layer is preferably 1 to 1000 μm, more preferably 5 to 700 μm, further preferably 10 to 500 μm, particularly preferably 15 to 200 μm, especially 20 to 100 μm, and most preferably 25 to 60 μm. This makes it easier to meet the optical properties described below while also providing excellent unevenness embedding properties.

[0046] Figure 1A FIG shows an adhesive sheet 1 having two adhesive layers. Figure 1B ] shows an adhesive sheet 1 having a single adhesive layer.

[0047] Figure 1A The adhesive sheet 1 shown comprises an adhesive layer 10 (a first adhesive layer 11 and a second adhesive layer 12) and release sheets 20a and 20b. The principal surfaces 11a and 12a of the first adhesive layer 11 and the second adhesive layer 12 are in contact with each other. Furthermore, the release sheet 20a is arranged such that its release surface contacts the principal surface 11b of the first adhesive layer 11; and the release sheet 20b is arranged such that its release surface contacts the principal surface 12b of the second adhesive layer 12.

[0048] Figure 1B The adhesive sheet 1 shown includes an adhesive layer 10 and release sheets 20 a and 20 b . The release sheets 20 a and 20 b are arranged so that their release surfaces come into contact with both main surfaces of the adhesive layer 10 .

[0049] In this specification, the release surface of the release sheet refers to a surface of the release sheet that has releasability, and includes both a surface that has been subjected to a release treatment and a surface that exhibits releasability even without being subjected to a release treatment.

[0050] (2.1. Physical Properties of Adhesive Layer)

[0051] The adhesive layer of this embodiment preferably has the following physical properties: When the adhesive layer is composed of multiple layers, the physical properties shown below are the physical properties exhibited by the adhesive layer as a whole.

[0052] (2.1.1. Total light transmittance of adhesive layer)

[0053] The total light transmittance of the adhesive layer of this embodiment is preferably 5% or more and 95% or less. This allows for both seamlessness and visibility of images displayed on the display.

[0054] From the viewpoint of visibility, the total light transmittance is preferably 10% or more, more preferably 15% or more, further preferably 20% or more, and particularly preferably 25% or more.

[0055] Furthermore, from the perspectives of seamlessness and concealment, the total light transmittance is preferably 85% or less, more preferably 75% or less, even more preferably 65% ​​or less, particularly preferably 55% or less, and even more preferably 46% or less. The total light transmittance in this specification is the value measured in accordance with JIS K7361-1:1997.

[0056] (2.1.2. Haze value of adhesive layer)

[0057] The haze value of the adhesive layer of this embodiment is preferably 5% or more and 99.9% or less. This allows for both concealment and visibility to be achieved.

[0058] From the viewpoint of concealment, the haze value is preferably 10% or more, more preferably 15% or more, further preferably 25% or more, particularly preferably 35% or more, and particularly preferably 45% or more.

[0059] Furthermore, from the perspective of image visibility and screen color tone displayed on the display, the haze value is preferably 98% or less, more preferably 96% or less, and even more preferably 94% or less. Furthermore, from the perspective of achieving both concealment and seamlessness, the haze value is preferably 90% or less, more preferably 80% or less, particularly preferably 70% or less, even more preferably 60% or less, and even more preferably 55% or less. The haze values ​​herein are values ​​measured in accordance with JIS K7136:2000.

[0060] (2.1.3. Lightness and chromaticity of adhesive layer)

[0061] The adhesive layer of this embodiment preferably has a lightness L* of 95 or less, as defined by the CIE 1976 L*a*b* color system. This facilitates satisfying the aforementioned total light transmittance while also achieving both seamlessness and concealment properties in combination with the aforementioned haze value. From this perspective, the lightness L* is preferably 1 to 90, more preferably 10 to 85, even more preferably 20 to 80, particularly preferably 30 to 75, and even more preferably 40 to 65.

[0062] The chromaticity a* defined by the CIE 1976 L*a*b* colorimetric system is preferably -30 to 30, more preferably -15 to 15, even more preferably -5 to 5, and particularly preferably -1 to 1. Furthermore, the chromaticity b* defined by the CIE 1976 L*a*b* colorimetric system is preferably -30 to 30, more preferably -15 to 15, even more preferably -8 to 8, and particularly preferably -4 to 4. By setting the chromaticity a* and chromaticity b* within the above ranges, the visibility and color rendering properties of the image displayed by the display are improved.

[0063] (2.1.4. Gel Fraction of Adhesive Layer)

[0064] The gel fraction of the adhesive layer of this embodiment is preferably 20-95%, more preferably 30-90%, further preferably 40-80%, particularly preferably 50-75%, and even more preferably 53-70%. As a result, the adhesive layer exhibits good cohesiveness while easily exhibiting the desired adhesive force, easily achieving excellent uneven embedding properties. For example, when multiple adhesive layers are stacked, the adhesive layers can be easily stacked together, resulting in a laminate that fully exhibits the desired optical properties. The method for measuring the gel fraction of the adhesive will be described in detail in the Examples described below.

[0065] When the adhesive layer of this embodiment is an active energy ray curable adhesive, the gel fraction of the adhesive layer before active energy ray irradiation is preferably 20 to 95%, more preferably 30 to 85%, further preferably 35 to 75%, particularly preferably 40 to 65%, and especially preferably 45 to 55%. In addition, the gel fraction of the adhesive layer after active energy ray irradiation is preferably 30 to 99%, more preferably 40 to 90%, further preferably 45 to 85%, and especially preferably 50 to 80%. It is particularly preferably 55 to 75%. Thus, the adhesive layer is easy to exert the desired adhesion while exerting good cohesion, and it is easy to become excellent in concave and convex embedding properties. For example, when multiple adhesive layers are stacked, since the adhesive layers are easy to stack well with each other, a laminate that fully exerts the desired optical properties can be obtained.

[0066] (2.1.5. Adhesion of the Adhesive Layer)

[0067] In this embodiment, the adhesion of the adhesive layer to the soda-lime glass is preferably 1 to 100 N / 25 mm. This ensures sufficient adhesion to the adhered object and makes it easy to achieve excellent concave-convex embedding properties. For example, when multiple adhesive layers are stacked, since the adhesive layers are easy to stack well with each other, a laminate that fully demonstrates the desired optical properties can be obtained. From the above perspectives, the adhesion is more preferably 4 to 70 N / 25 mm, further preferably 8 to 50 N / 25 mm, particularly preferably 12 to 40 N / 25 mm, and even more preferably 16 to 32 N / 25 mm. The method for measuring the adhesion of the adhesive layer will be described in detail in the examples described below.

[0068] When the adhesive layer of this embodiment is an active energy ray-curable adhesive, the adhesive strength of the adhesive layer to the soda-lime glass before irradiation with active energy rays is more preferably 1 to 100 N / 25 mm, further preferably 5 to 70 N / 25 mm, particularly preferably 10 to 50 N / 25 mm, and particularly preferably 15 to 35 N / 25 mm. Furthermore, the adhesive strength of the adhesive layer to the soda-lime glass after irradiation with active energy rays is more preferably 1 to 100 N / 25 mm, further preferably 6 to 80 N / 25 mm, particularly preferably 12 to 60 N / 25 mm, and particularly preferably 18 to 40 N / 25 mm. This ensures sufficient adhesion to the adherend and facilitates excellent uneven embedding properties. For example, when multiple adhesive layers are stacked, the adhesive layers can be easily stacked together, resulting in a laminate that fully exhibits the desired optical properties.

[0069] (2.1.6. Concave-convex embedding properties)

[0070] The degree to which the adhesive layer of the component of this embodiment embeds the unevenness, i.e., the unevenness embedding property, can be determined using the unevenness embedding rate (%) as an indicator. The unevenness embedding rate (%) of the adhesive layer, as expressed by the following formula, is preferably 10% or greater, more preferably 20% or greater, even more preferably 30% or greater, and particularly preferably 40% or greater as a lower limit. Furthermore, while there is no particular upper limit, the unevenness embedding rate is generally preferably 80% or less.

[0071] Concave-convex embedding rate (%) = {(height of the step that remains buried without bubbles, floating, peeling, etc. after the specified durability test (μm)) / (thickness of the adhesive layer (μm))}×100

[0072] The test method of the unevenness embedding ratio is shown in the test examples described later.

[0073] (2.2. Composition of Adhesive Layer)

[0074] The composition of the adhesive layer of this embodiment is not particularly limited as long as it contains the above-mentioned components and has the above-mentioned physical properties.

[0075] (2.2.1. Adhesive ingredients)

[0076] As the composition system of the adhesive component included in the adhesive layer, for example, acrylic adhesive, polyester adhesive, polyurethane adhesive, rubber adhesive, silicone adhesive can be exemplified. When the adhesive layer is composed of more than two layers, the composition system of the adhesive component can be the same or different in each adhesive layer. In addition, the form of the adhesive component can be any one of emulsion type, solvent type or solvent-free type. Further, the adhesive component can have a cross-linked structure or may not have a cross-linked structure.

[0077] In this embodiment, when the adhesive layer is composed of two or more layers, the adhesive components contained in each adhesive layer are preferably of the same composition system and the same form. In addition, from the perspective of the ease of achieving the above-mentioned physical properties, as well as the adhesive physical properties and optical characteristics, the adhesive component is preferably an acrylic adhesive, and more preferably an acrylic adhesive having a cross-linked structure.

[0078] The acrylic adhesive is preferably an adhesive obtained from an adhesive composition containing a (meth)acrylate polymer (A) as the main component (hereinafter sometimes referred to as "adhesive composition P"). In particular, the acrylic adhesive having a cross-linked structure is preferably an adhesive obtained by cross-linking an adhesive composition P containing a (meth)acrylate polymer (A) and a cross-linking agent (B). As long as this adhesive is used, it is easy to meet the above-mentioned physical properties and easy to obtain good adhesion. In addition, in this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are the same. In addition, the concept of "polymer" includes "copolymer".

[0079] (2.2.2. (Meth)acrylate polymers)

[0080] The (meth)acrylate polymer (A) preferably contains an alkyl (meth)acrylate and a monomer having a reactive functional group in the molecule (a monomer containing a reactive functional group) as monomer units constituting the polymer. This facilitates obtaining an adhesive having a cross-linked structure and excellent adhesion and optical properties. In particular, it tends to facilitate good dispersion of the coloring component (C) and light-diffusing component (D), described later, in the adhesive. The resulting adhesive becomes a suitable adhesive capable of exhibiting the desired adhesion, while also improving the aforementioned optical properties and exhibiting excellent seamlessness and concealing properties.

[0081] The (meth)acrylate polymer (A) preferably contains a nitrogen-containing monomer as a monomer unit constituting the polymer. This imparts a predetermined polarity to the adhesive, making it easier to obtain an adhesive with excellent affinity even for adherends with a certain degree of polarity, such as glass. Furthermore, the adhesive tends to have good dispersibility of the coloring component (C) and the light-diffusing component (D), described later, in the adhesive. The resulting adhesive exhibits both suitable adhesion and improved optical properties, demonstrating excellent seamlessness and concealment.

[0082] The (meth)acrylate polymer (A) preferably contains a monomer having an alicyclic structure in the molecule (a monomer containing an alicyclic structure) as a monomer unit constituting the polymer. Since the monomer containing an alicyclic structure is bulky, it is presumed that by allowing it to be present in the polymer, the intervals between the polymers will be widened, and the resulting adhesive will have excellent flexibility. Thus, the adhesion to the adhered object can be fully ensured. In addition, there is a tendency to be able to well combine the dispersibility of the coloring component (C) and the light diffusion component (D) described later in the adhesive. The resulting adhesive, while being able to exert suitable adhesion, has the above-mentioned optical properties improved, showing excellent seamlessness and concealment.

[0083] The (meth)acrylate polymer (A) preferably contains an aromatic ring-containing monomer as a monomer unit constituting the polymer. Thus, since the adhesive is given a predetermined rigidity and adhesion, it is easy to obtain an adhesive exhibiting good adhesion. Furthermore, there is a tendency to achieve good dispersibility of the coloring component (C) and the light-diffusing component (D) described later in the adhesive. The resulting adhesive exhibits good optical properties while exhibiting suitable adhesion, exhibiting excellent seamlessness and concealment.

[0084] The (meth)acrylate polymer (A) contains an alkyl (meth)acrylate as a monomer unit constituting the polymer, so that the resulting adhesive exhibits excellent adhesiveness. The alkyl (meth)acrylate is preferably one having an alkyl group with 1 to 20 carbon atoms. The alkyl group may be linear or branched, or may have a cyclic structure.

[0085] Examples of the alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms 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, and stearyl (meth)acrylate.

[0086] Among these, from the perspective of dispersibility of the coloring component (C) and light-diffusing component (D) described below in the adhesive and the ease with which the resulting adhesive can satisfy both adhesiveness and optical properties, (meth)acrylates having an alkyl group with 1 to 8 carbon atoms are preferred, and (meth)acrylates having an alkyl group with 4 to 8 carbon atoms are particularly preferred. Specifically, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate are preferred, with n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate being particularly preferred. These may be used alone or in combination of two or more.

[0087] The (meth)acrylate polymer (A) preferably contains 30 to 99.9% by mass of an alkyl (meth)acrylate having an alkyl group with 1 to 20 carbon atoms as monomer units constituting the polymer, and more preferably contains 40 to 99% by mass. Furthermore, when the (meth)acrylate polymer (A) contains a nitrogen-containing monomer or an alicyclic structure-containing monomer as monomer units constituting the polymer, it is further preferred that it contain 45 to 90% by mass of an alkyl (meth)acrylate having an alkyl group with 1 to 20 carbon atoms, particularly preferably 50 to 80% by mass, and even more preferably 55 to 70% by mass. Furthermore, when the (meth)acrylate polymer (A) contains an aromatic ring-containing monomer as monomer units constituting the polymer, it is further preferred that it contain 50 to 98% by mass of an alkyl (meth)acrylate having an alkyl group with 1 to 20 carbon atoms, and particularly preferably 60 to 97.5% by mass. This allows the (meth)acrylate polymer (A) to have suitable adhesiveness while exhibiting the aforementioned good optical properties. Furthermore, a desired amount of other monomer components can be introduced into the (meth)acrylate polymer (A), making it easy to design an adhesive that exhibits desired performance.

[0088] Since the (meth)acrylate polymer (A) contains a monomer containing a reactive functional group as a monomer unit constituting the polymer, the (meth)acrylate polymer (A) can react with the crosslinking agent (B) described below via the reactive functional groups derived from the reactive functional group-containing monomer, thereby forming a crosslinked structure (three-dimensional network structure) in the adhesive. As a result, an adhesive having the desired cohesive force can be obtained, and the adhesive can easily meet the desired adhesive strength.

[0089] As the monomer containing a reactive functional group, from the perspective of dispersibility of the coloring component (C) and the light diffusing component (D) described later in the adhesive, preferably a monomer containing a functional group exhibiting hydrophilicity is used, and particularly preferably a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. These monomers containing a reactive functional group may be used alone or in combination of two or more.

[0090] Among the monomers containing reactive functional groups, hydroxyl group-containing monomers or carboxyl group-containing monomers are preferred, with hydroxyl group-containing monomers being particularly preferred. The inclusion of hydroxyl group-containing monomers tends to improve the dispersibility of the coloring component (C) and light-diffusing component (D) described below in the adhesive, resulting in excellent seamlessness and concealing properties.

[0091] As the hydroxyl-containing monomer, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate can be exemplified. Among them, from the perspective of the dispersibility of the coloring component (C) and the light diffusion component (D) described later in the adhesive, hydroxyalkyl (meth)acrylates having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred. Specifically, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. can be preferably cited, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate can be particularly preferably cited. These can be used alone or in combination of two or more.

[0092] Examples of carboxyl group-containing monomers 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 perspective of the dispersibility of the coloring component (C) and the light-diffusing component (D) described below in the adhesive and the adhesive strength of the resulting adhesive. These monomers may be used alone or in combination of two or more.

[0093] The (meth)acrylate polymer (A) preferably contains 0.1 to 50% by mass of a monomer containing a reactive functional group as a monomer unit constituting the polymer. When not used simultaneously with an aromatic ring-containing monomer, the polymer preferably contains 4 to 40% by mass of the monomer containing a reactive functional group, more preferably 8 to 35% by mass, further preferably 12 to 30% by mass, and particularly preferably 15 to 25% by mass. Furthermore, when used simultaneously with an aromatic ring-containing monomer, the polymer preferably contains 0.3 to 30% by mass of the monomer containing a reactive functional group, more preferably 0.6 to 20% by mass, further preferably 0.8 to 10% by mass, and further preferably 1 to 3% by mass.

[0094] By setting the content of the reactive functional group-containing monomer within the above range, the cohesive force of the adhesive obtained through the crosslinking reaction with the crosslinking agent (B) becomes moderate, and the desired adhesive force is easily achieved. In addition, there is a tendency to improve the dispersibility of the coloring component (C) and the light-diffusing component (D) described later in the adhesive. The resulting adhesive can not only exhibit appropriate adhesiveness, but also improve the above-mentioned optical properties, showing excellent seamlessness and concealing properties.

[0095] The (meth)acrylate polymer (A) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since carboxyl groups are acid components, the absence of carboxyl group-containing monomers can suppress acid-induced adverse effects (corrosion, resistance change, etc.) even when the adhesive is applied to a target surface containing substances that can cause adverse effects due to acid, such as transparent conductive films such as tin-doped indium oxide (ITO), metal films, and metal meshes.

[0096] Here, "containing no carboxyl group-containing monomers" means substantially containing no carboxyl group-containing monomers, and includes not only cases in which no carboxyl group-containing monomers are contained at all but also cases in which carboxyl group-containing monomers are contained to such an extent that no corrosion of the transparent conductive film, metal wiring, etc. due to the carboxyl groups occurs. Specifically, the (meth)acrylate polymer (A) may contain a carboxyl group-containing monomer as a monomer unit in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

[0097] As the monomer containing nitrogen atoms, monomers having amino groups, monomers having amide groups, monomers having nitrogen-containing heterocycles, etc. can be cited. Among them, from the perspective of maintaining appropriate rigidity and polarity of the (meth)acrylate polymer (A) and the dispersibility of the coloring component (C) and the light diffusion component (D) described later in the adhesive, monomers having nitrogen-containing heterocycles are preferred. In addition, from the perspective of increasing the degree of freedom of the part of the nitrogen-containing monomer in the high-dimensional structure of the adhesive formed, it is preferred that the nitrogen-containing monomer does not contain a reactive unsaturated double bond group except for a polymerizable group used in the polymerization for forming the (meth)acrylate polymer (A). One type of nitrogen-containing monomer can be used alone, or two or more types can be used in combination.

[0098] Examples of the monomer having an amino group include monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, and dimethylaminoethyl (meth)acrylate.

[0099] Examples of the monomer having an amide group include (meth)acrylamide, N-methyl(meth)acrylamide, N-methylol(meth)acrylamide, N-tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-phenyl(meth)acrylamide, N-(n-butoxymethyl)(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, and N-vinylcaprolactam.

[0100] Examples of the nitrogen-containing heterocyclic monomer include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. N-(meth)acryloylmorpholine is preferred, and N-acryloylmorpholine is particularly preferred.

[0101] The (meth)acrylate polymer (A) preferably contains 1 to 20% by mass, more preferably 3 to 12% by mass, and even more preferably 4 to 8% by mass of a nitrogen-containing monomer as a monomer unit. This ensures sufficient adhesion to the adherend and simultaneously allows for good dispersibility of the coloring component (C) and light-diffusing component (D), described below, in the adhesive. Consequently, the resulting adhesive exhibits both suitable adhesion and excellent optical properties, including superior seamlessness and concealing properties.

[0102] The carbon ring of the alicyclic structure of the monomer containing the alicyclic structure may be a saturated structure or may have an unsaturated bond in a part. In addition, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure (polycyclic structure) such as a bicyclic or tricyclic alicyclic structure. From the perspective of making the distance between the obtained (meth)acrylate polymers (A) appropriate and imparting higher stress relaxation properties to the adhesive, the above-mentioned alicyclic structure is preferably a polycyclic structure. Furthermore, considering the compatibility of the (meth)acrylate polymer (A) with other components, the above-mentioned polycyclic structure is particularly preferably a bicyclic to tetracyclic structure. In addition, from the perspective 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 multiple rings exist independently, it refers to the total number of carbon atoms) is preferably 5 to 15, and more preferably 7 to 10.

[0103] Specific examples of the monomer containing an alicyclic structure include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among these, dicyclopentanyl (meth)acrylate (alicyclic structure with 10 carbon atoms), adamantyl (meth)acrylate (alicyclic structure with 10 carbon atoms), and isobornyl (meth)acrylate (alicyclic structure with 7 carbon atoms) are preferred, as they exhibit superior adhesion. Isobornyl (meth)acrylate is more preferred, and isobornyl acrylate is particularly preferred. These monomers may be used alone or in combination of two or more.

[0104] The (meth)acrylate polymer (A) preferably contains 1 to 30% by mass, more preferably 5 to 24% by mass, and even more preferably 10 to 18% by mass of a monomer containing an alicyclic structure as a monomer unit constituting the polymer. This improves the flexibility of the resulting adhesive, enabling the desired and appropriate adhesive properties to be exhibited. Furthermore, this tends to achieve good dispersibility of the coloring component (C) and the light-diffusing component (D), described below, in the adhesive, resulting in an adhesive having improved optical properties and exhibiting excellent seamlessness and concealing properties.

[0105] Examples of aromatic ring-containing monomers include phenyl (meth)acrylate, 2-phenylethyl (meth)acrylate, benzyl (meth)acrylate, naphthyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, phenoxybutyl (meth)acrylate, ethoxylated o-phenylphenol acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, biphenyl di(meth)acrylate, and pentafluorobenzyl (meth)acrylate. Among these, 2-phenoxyethyl (meth)acrylate is preferred, and 2-phenoxyethyl acrylate is particularly preferred, from the perspective of dispersibility of the coloring component (C) and the light-diffusing component (D) described below in the adhesive and the adhesiveness of the resulting adhesive. These monomers may be used alone or in combination of two or more.

[0106] The (meth)acrylate copolymer (A) preferably contains 0.1 to 10% by mass, more preferably 0.4 to 6% by mass, further preferably 0.8 to 3% by mass, and particularly preferably 1 to 2% by mass of an aromatic ring-containing monomer as a monomer unit constituting the polymer. Thus, since the adhesive is given the prescribed rigidity and adhesion, it is easy to obtain an adhesive exhibiting good adhesion. Furthermore, there is a tendency to achieve good dispersibility of the coloring component (C) and the light-diffusing component (D) described later in the adhesive. The resulting adhesive, while being able to exhibit appropriate adhesion, also exhibits good optical properties, showing excellent seamlessness and concealment.

[0107] In this embodiment, the (meth)acrylate polymer (A) may contain other monomers as monomer units constituting the polymer as desired. As other monomers, monomers that do not contain reactive functional groups are preferred so as not to hinder the aforementioned effects of the monomer containing a reactive functional group. Examples of such monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These monomers may be used alone or in combination of two or more.

[0108] The polymerization form of the (meth)acrylate polymer (A) may be a random copolymer or a block copolymer.

[0109] The weight average molecular weight of the (meth)acrylate polymer (A) is preferably 100,000 to 3,000,000, more preferably 200,000 to 2,400,000, and even more preferably 300,000 to 1,800,000. When the (meth)acrylate polymer (A) contains an aromatic ring-containing monomer as a monomer unit constituting the polymer, the weight average molecular weight is preferably 600,000 to 1,500,000, more preferably 800,000 to 1,300,000. In addition, when the (meth)acrylate polymer (A) does not contain an aromatic ring-containing monomer as a monomer unit constituting the polymer, the weight average molecular weight is preferably 350,000 to 1,200,000, more preferably 400,000 to 900,000, and even more preferably 450,000 to 700,000. Thus, the resulting adhesive exhibits the desired adhesiveness. In addition, it has a tendency to be able to well combine the dispersibility of the coloring component (C) and the light diffusion component (D) described later in the adhesive without damaging the adhesiveness, and the above-mentioned optical properties are good, showing excellent seamlessness and concealment. In addition, the weight average molecular weight in this specification is a value converted into standard polystyrene measured by gel permeation chromatography (GPC).

[0110] In the adhesive composition P, the (meth)acrylate polymer (A) may be used alone or in combination of two or more.

[0111] (2.2.3. Cross-linking agent (B))

[0112] When the adhesive composition P containing the crosslinking agent (B) is heated, for example, the crosslinking agent (B) crosslinks the (meth)acrylate polymer (A), forming a crosslinked structure (three-dimensional network structure). As a result, the cohesive force of the resulting adhesive is enhanced, making it easier to achieve the desired adhesive strength and achieving excellent adhesion to the adherend.

[0113] As crosslinking agent (B), it is sufficient to react with the reactive group possessed by (meth) acrylate polymer (A). For example, isocyanate crosslinking agent, epoxy crosslinking agent, amine crosslinking agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. can be illustrated. When the reactive functional group possessed by (meth) acrylate polymer (A) is hydroxyl, it is preferred to use an isocyanate crosslinking agent with excellent reactivity with hydroxyl. On the other hand, when the reactive functional group possessed by (meth) acrylate polymer (A) is carboxyl, it is preferred to use an epoxy crosslinking agent with excellent reactivity with carboxyl. In addition, crosslinking agent (B) can be used alone or in combination of two or more.

[0114] Isocyanate-based crosslinking agents contain at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret and isocyanurate forms, as well as adducts thereof with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates are preferred due to their reactivity with hydroxyl groups.

[0115] Examples of epoxy crosslinking agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidol, and amines. Among these, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane and N,N,N',N'-tetraglycidyl-m-xylenediamine are preferred from the perspective of reactivity with carboxyl groups.

[0116] The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass, and particularly preferably 0.04 to 1 part by mass relative to 100 parts by mass of the (meth)acrylate polymer (A). When a hydroxyl group is included as the reactive group possessed by the (meth)acrylate polymer (A), the content is further preferably 0.07 to 0.7 parts by mass, and particularly preferably 0.1 to 0.4 parts by mass. In addition, when a carboxyl group is included as the reactive group possessed by the (meth)acrylate polymer (A), the content is further preferably 0.04 to 0.5 parts by mass, and particularly preferably 0.05 to 0.1 parts by mass. Thus, it is easy to obtain an adhesive having a desired crosslinked structure and cohesive force. In particular, since the desired cross-linked structure can be easily formed while maintaining the dispersibility of the coloring component (C) and the light-diffusing component (D) described later in the adhesive, the resulting adhesive, while exhibiting the desired adhesiveness, satisfies the above-mentioned optical properties and shows excellent seamlessness and concealment.

[0117] (2.2.4. Coloring ingredient (C))

[0118] In this embodiment, the adhesive layer as a whole preferably contains a coloring component. When the adhesive layer is composed of two or more layers, it is preferred that at least one layer contains a coloring component. In addition, the coloring component can be used alone or in combination of two or more. In addition, when multiple layers contain a coloring component, the coloring components of each layer can be the same or different. When the adhesive layer is one layer, the adhesive layer can contain one coloring component or two or more coloring components.

[0119] By including a coloring component, the optical properties of the adhesive layer (total light transmittance, lightness L* specified by the CIE1976 L*a*b* color system, chromaticity a* and chromaticity b*, etc.) can be adjusted to the desired range, thereby improving the design of the display body to which the adhesive layer is bonded, especially its seamlessness.

[0120] The coloring component may be a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. Inorganic pigments are preferred from the perspective of the durability of the resulting adhesive and the ease with which the aforementioned optical properties are met. The color of the coloring component can be appropriately selected to match the color of the display components, taking into account factors such as seamlessness and the color tone of the image. However, dark or deep colors such as black, brown, navy blue, purple, and blue are generally preferred, with black being particularly preferred.

[0121] Examples of the inorganic pigments include carbon black, cobalt pigments, iron pigments, chromium pigments, titanium pigments, vanadium pigments, zirconium pigments, molybdenum pigments, ruthenium pigments, platinum pigments, indium tin oxide (ITO) pigments, and antimony tin oxide (ATO) pigments.

[0122] Examples of organic pigments and organic dyes include amine pigments, cyanine pigments, merocyanine pigments, croconium pigments, squarylium pigments, azulenium pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, phthalocyanine pigments, naphthalocyanine pigments, naphtholactam pigments, azo pigments, condensed azo pigments, indigo pigments, perinone pigments, perylene pigments, and dioxazine pigments. , quinacridone pigments, isoindolinone pigments, quinolinone pigments, pyrrole pigments, thioindigo pigments, metal complex pigments (metal complex salt dyes), dithiol metal complex pigments, indoxyl pigments, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, naphthol pigments, azomethine pigments, benzimidazolone pigments, pyranthron pigments and threne pigments, etc.

[0123] Examples of black pigments include carbon black, copper oxide, ferrosoferric oxide, manganese dioxide, aniline black, activated carbon, etc. Examples of black dyes include high-concentration plant dyes and azo dyes.

[0124] The above-mentioned pigments or dyes can be appropriately mixed and used so as to obtain target physical properties in the adhesive layer.

[0125] Among the aforementioned coloring components, black pigments or dyes are preferred from the perspectives of easily satisfying the aforementioned physical properties, seamlessness, and color tone of the image. Carbon black, nigrosine-based black dyes, and chromate-based black dyes are particularly preferred. The surface of the carbon black may or may not be subjected to a prescribed treatment (e.g., solvophilic treatment).

[0126] From the perspective of optical properties, the coloring component (C) preferably satisfies the following properties. By using a suitable amount of a coloring component that satisfies the following properties, the optical properties (total light transmittance, haze, brightness, chromaticity, etc.) of the adhesive layer can be easily satisfied. Furthermore, in combination with the effect of the light-diffusing component (D) described below, the optical properties of the resulting adhesive layer can be adjusted to facilitate concealment.

[0127] Regarding the coloring component (C), the average haze, which is the average of the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm, of a solution prepared by diluting the coloring component 10,000 times with ethyl acetate is preferably 1 to 60%, particularly preferably 2 to 40%, and further preferably 3 to 30%. From the perspective of easily achieving both seamless properties and color tone, it is particularly preferably 3.5 to 20%, and even more preferably 4 to 10%.

[0128] Regarding the coloring component (C), the difference between the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm of a solution prepared by diluting the coloring component 10,000 times with ethyl acetate is preferably 0 to 30 percentage points, more preferably 1 to 20 percentage points. From the perspective of easily achieving both seamless properties and color tone, it is particularly preferably 2 to 10 percentage points, and even more preferably 3 to 8 percentage points.

[0129] The haze value at a wavelength of 780 nm of a solution prepared by diluting the coloring component (C) 10,000 times with ethyl acetate is preferably 0.1 to 50%, more preferably 0.5 to 30%, particularly preferably 1 to 20%, and even more preferably 2 to 10%, from the perspective of easily achieving both seamlessness and color tone. Furthermore, the haze value at a wavelength of 380 nm of a solution prepared by diluting the coloring component 10,000 times with ethyl acetate is preferably 1 to 60%, more preferably 3 to 40%, and particularly preferably 6 to 30%, and even more preferably 10 to 20%, from the perspective of easily achieving both seamlessness and color tone.

[0130] The standard deviation of the haze value of a solution prepared by diluting the coloring component (C) 10,000 times with ethyl acetate at each wavelength of 5 nm intervals in the wavelength range of 380 nm to 780 nm (i.e., 380 nm, 385 nm, 390 nm, ..., 775 nm, 780 nm) is preferably 0.1 to 10, more preferably 0.4 to 7, and particularly preferably 0.8 to 4, and even more preferably 1 to 2, from the perspective of easily achieving both seamlessness and color tone.

[0131] The content of the coloring component (C) relative to 100 parts by mass of the (meth)acrylate polymer (A) is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, further preferably 0.05 to 2 parts by mass, particularly preferably 0.1 to 1 part by mass, particularly preferably 0.2 to 0.6 parts by mass, and most preferably 0.3 to 0.45 parts by mass. This makes it easier to satisfy the aforementioned optical properties (total light transmittance, haze, brightness, chromaticity, etc.). Furthermore, combined with the effect of the light-diffusing component (D) described later, the resulting adhesive layer can be adjusted to exhibit optical properties that facilitate concealment.

[0132] The content of the coloring component in the adhesive layer (the content of the coloring component in the entire plurality of layers, if the adhesive layer is composed of multiple layers): α (mass %) is preferably 0.01 to 10, more preferably 0.05 to 5, even more preferably 0.1 to 1, particularly preferably 0.12 to 0.6, especially preferably 0.13 to 0.3, and most preferably 0.15 to 0.22. By designing the adhesive layer to meet these values, combined with the effect of the light-diffusing component (D) described below, the optical properties of the resulting adhesive layer can be adjusted to facilitate seamlessness and concealment. Furthermore, the visual recognition of the image as a display and the color tone of the screen are easily improved.

[0133] When the total thickness of the adhesive layer (or the total thickness of the multiple layers if the adhesive layer is composed of multiple layers) is T (μm), the product of this value and the above-mentioned α (mass %) (α×T) is preferably 0.1 to 1000, more preferably 0.5 to 500, even more preferably 1 to 200, particularly preferably 5 to 100, especially preferably 10 to 60, and most preferably 20 to 30. By designing the adhesive layer to satisfy this product value, combined with the effect of the light-diffusing component (D) described below, the optical properties of the resulting adhesive layer can be adjusted so that it easily exhibits seamlessness and concealment. In addition, the visibility of the image as a display and the color tone of the screen are easily improved.

[0134] (2.2.5. Light Diffusing Component (D))

[0135] In the present embodiment, as the adhesive layer as a whole, it is preferred to include a light diffusion component. When the adhesive layer is composed of more than two layers, it is preferred that at least one layer includes a light diffusion component. In addition, the light diffusion component can be used alone or in combination with two or more. In addition, when multiple layers include light diffusion components, the light diffusion components of each layer can be the same or different. When the adhesive layer is one layer, the adhesive layer can include one light diffusion component or two or more light diffusion components.

[0136] By including a light-diffusing component, the total light transmittance of the adhesive layer can be maintained while the haze value can be easily adjusted to a desired range, thereby improving the concealment of the display body to which the adhesive layer is applied. In other words, by including a coloring component and a light-diffusing component throughout the adhesive layer, the total light transmittance and haze value of the adhesive layer can be easily and effectively controlled.

[0137] As the light diffusion component, light diffusion particles are preferred. As light diffusion particles, for example, inorganic particles such as silicon dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, titanium dioxide, etc.; organic light-transmitting particles such as acrylic resin, polystyrene resin, polyethylene resin, epoxy resin, etc.; particles composed of silicon-containing compounds with an intermediate structure between inorganic and organic, such as silicone resin (for example, the TOSPEARL series manufactured by Momentive Performance Materials Japan), etc. Among them, acrylic resin particles and particles composed of silicon-containing compounds with an intermediate structure between inorganic and organic, are preferred because they have excellent dispersibility in the above-mentioned adhesive components and can obtain uniform optical properties. Light diffusion particles can be used alone or in combination of two or more.

[0138] The shape of the light-diffusing particles may be either fixed or irregular, but from the viewpoint of excellent dispersibility in the above-mentioned adhesive component, fixed-shaped particles are preferred, spherical particles are more preferred, and round spherical particles are particularly preferred.

[0139] The average particle size of the light-diffusing particles is preferably 0.1 to 20 μm, more preferably 1 to 16 μm. When the light-diffusing particles are particles composed of a silicon-containing compound, the average particle size is further preferably 2 to 12 μm, particularly preferably 3 to 10 μm, and even more preferably 4 to 8 μm. This makes it easier to adjust the haze value to the above range without hindering the light transmittance of the adhesive layer. In particular, combined with the effect of the coloring component (C), the optical properties of the resulting adhesive layer can be adjusted to further enhance its concealing properties.

[0140] The average particle size of the light-diffusing particles is preferably smaller than the thickness of the adhesive layer (single layer) containing the light-diffusing particles. Specifically, when the average particle size of the light-diffusing particles is set to X (μm) and the thickness of the adhesive layer (single layer) containing the light-diffusing particles is set to Y (μm), the ratio (X / Y) is preferably 0.001 to 0.8, more preferably 0.01 to 0.4, further preferably 0.02 to 0.5, particularly preferably 0.04 to 0.2, and especially preferably 0.07 to 0.15. Thus, the light-diffusing particles do not protrude from the obtained adhesive layer to form a good adhesive surface, thereby exhibiting the desired adhesive force and achieving good adhesion to the adherend. In addition, it is easy to form a uniformly dispersed state in the adhesive layer, thereby forming an adhesive layer that exhibits the above-mentioned optical properties.

[0141] The average particle size can be measured by a centrifugal sedimentation light transmission method using a centrifugal automatic particle size distribution analyzer (CAPA-700 manufactured by HORIBA, Ltd.) using a mixture obtained by thoroughly stirring 1.2 g of the particles with 98.8 g of isopropyl alcohol as a measurement sample.

[0142] The refractive index of the light-diffusing particles is preferably 1.20 to 1.80, more preferably 1.30 to 1.70, further preferably 1.35 to 1.60, and particularly preferably 1.40 to 1.50. This makes it easier to satisfy the aforementioned optical properties. The refractive index of the light-diffusing particles can be measured, for example, by the following method. Specifically, the particles are placed on a glass slide, a refractive index standard solution is dripped onto the particles, and a cover glass is placed on the surface to prepare a sample. The sample is observed under a microscope, and the refractive index of the refractive index standard solution at which the particle outline is least visible is taken as the refractive index of the particles.

[0143] When the adhesive composition P contains a (meth)acrylate polymer (A) as an adhesive component, the content of the light-diffusing particles is preferably 0.1 to 50 parts by mass, more preferably 0.4 to 30 parts by mass, and even more preferably 0.8 to 20 parts by mass relative to 100 parts by mass of the (meth)acrylate polymer (A). When the light-diffusing particles are composed of a silicon-containing compound having an intermediate structure between organic and inorganic, such as a silicone resin, the content is more preferably 1 to 15 parts by mass, more preferably 1.4 to 10 parts by mass, particularly preferably 1.7 to 5 parts by mass, and even more preferably 2 to 3 parts by mass. In addition, when the light-transmitting particles are organic, the content is more preferably 1.1 to 10 parts by mass, further preferably 1.2 to 5 parts by mass, and even more preferably 1.3 to 2 parts by mass. By making the content of the light-diffusing particles within the above range, the haze value of the adhesive layer can be made within the above range, and good concealment can be obtained. Moreover, when the adhesive component is other than an acrylic adhesive component, the content of the light-diffusing particles is preferably within the above-mentioned range relative to 100 parts by mass of the adhesive component.

[0144] The light-diffusing component content in the adhesive layer (when the adhesive layer is composed of multiple layers, the light-diffusing component content of the multiple layers as a whole): β (mass %) is preferably 0.01 to 100, more preferably 0.05 to 50, even more preferably 0.1 to 20, particularly preferably 0.3 to 10, especially preferably 0.6 to 5, and most preferably 0.8 to 1.5. By designing the adhesive layer to meet these values, combined with the effects of the coloring component (C), the optical properties of the resulting adhesive layer can be adjusted to facilitate seamlessness and concealment. Furthermore, the visual recognition of the image as a display and the color tone of the screen are easily improved.

[0145] When the total thickness of the adhesive layer (the total thickness of the multiple layers when the adhesive layer is composed of multiple layers) is represented by T (μm), the product of this value and the above-mentioned β (mass %) (β×T) is preferably 1 to 10,000, more preferably 5 to 5,000, even more preferably 10 to 2,000, particularly preferably 30 to 1,000, especially preferably 60 to 600, and most preferably 80 to 150. By designing the adhesive layer to satisfy this product value, combined with the effect of the above-mentioned coloring component (C), the optical properties of the resulting adhesive layer can be adjusted to facilitate seamlessness and concealment. In addition, the visibility of the image as a display and the color tone of the screen are easily improved.

[0146] The ratio of α (mass %) to β (mass %) (β / α) is preferably 0.1 to 100, more preferably 0.5 to 80, even more preferably 1 to 60, particularly preferably 2 to 40, especially preferably 3 to 20, and most preferably 4 to 10. By designing the adhesive layer to satisfy this ratio, combined with the effect of the coloring component (C), the resulting adhesive layer can be adjusted to exhibit optical properties such as seamlessness and concealment. Furthermore, the visibility of the image displayed and the color tone of the screen are likely to be improved.

[0147] In addition, the coloring component (C) and the light diffusion component (D) can be distinguished by the method shown below. To 100 parts by mass of a (meth)acrylate polymer (weight average molecular weight Mw = 400,000) obtained by copolymerizing 99 parts by mass of n-butyl acrylate and 1 part by mass of acrylic acid, 1 part by mass of an additional component is added and mixed to obtain a coating solution of an adhesive composition. The obtained coating solution is applied to a substrate and dried to form an adhesive layer having a thickness of 50 μm. The lightness L* of the surface of the formed adhesive layer is measured. When the lightness L* is 90 or less, the added component is a coloring component, and when the lightness L* is greater than 90, the added component is a light diffusion component.

[0148] (2.2.6. Other additives)

[0149] The adhesive composition P may contain additives commonly used in adhesive components as needed. Examples of such additives include silane coupling agents, antistatic agents, active energy ray-curable components, photopolymerization initiators, ultraviolet absorbers, infrared absorbers, tackifiers, antioxidants, light stabilizers, softeners, rust inhibitors, fillers, and refractive index modifiers. Furthermore, the polymerization solvent or dilution solvent described below is not included in the additives constituting the adhesive composition P.

[0150] (2.2.7. Silane coupling agent (E))

[0151] Among the above additives, the adhesive composition P preferably contains a silane coupling agent (E). This not only improves adhesion to the adherend but also prevents positional shifts at the interfaces between the adhesive layers when laminating multiple adhesive layers, enabling good lamination.

[0152] As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, good compatibility with the adhesive component, particularly the (meth)acrylate polymer (A), and light transparency is preferred.

[0153] Examples of such silane coupling agents include silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having epoxy structures such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and silicon compounds containing mercapto groups such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Silicon compounds containing amino groups; Silicon compounds containing amino groups such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; condensates of 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these with methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more.

[0154] The content of the silane coupling agent in the adhesive composition P is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1 part by mass, further preferably 0.1 to 0.7 part by mass, further preferably 0.15 to 0.5 part by mass, and particularly preferably 0.2 to 0.3 part by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A).

[0155] (2.2.8. Antistatic agent (F))

[0156] Among the above additives, the adhesive composition P preferably contains an antistatic agent (F) within a range that does not impair the above optical properties and adhesive properties. This allows the adhesive layer to exhibit excellent antistatic performance.

[0157] As antistatic agent, as long as antistatic property can be given to the adhesive layer, for example, ionic compounds, nonionic compounds etc. can be listed, preferably ionic compounds. Ionic compounds can be liquid (ionic liquid) or solid (ionic solid) at room temperature. Wherein, the ionic compound in this specification refers to the compound that cation and anion are mainly combined by electrostatic attraction. In addition, antistatic agent can be used alone or in combination of two or more.

[0158] Preferred ionic compounds include nitrogen-containing onium salts, sulfur-containing onium salts, phosphonium salts, alkali metal salts, and alkaline earth metal salts. Nitrogen-containing onium salts and alkali metal salts are particularly preferred from the perspective of easily imparting good antistatic properties to the resulting adhesive layer while maintaining the aforementioned optical and adhesive properties. The nitrogen-containing onium salt is preferably an ionic compound composed of a nitrogen-containing heterocyclic cation and a corresponding anion.

[0159] The content of the antistatic agent (F) in the adhesive composition P is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, further preferably 1 to 10 parts by mass, and particularly preferably 1.5 to 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylate polymer (A).

[0160] (2.2.9. Active Energy Ray-Curable Component (G))

[0161] When the adhesive component constituting the adhesive layer is active energy ray-curable, the adhesive composition P preferably contains an active energy ray-curable component (G). It is speculated that when the adhesive composition P, crosslinked, is subjected to active energy ray curing, the active energy ray-curable components (G) polymerize with each other, and the polymerized active energy ray-curable components (G) become entangled in the crosslinked structure (three-dimensional network structure) of the (meth)acrylate polymer (A). An adhesive having this high-dimensional structure can exhibit extremely excellent durability.

[0162] The active energy ray curable component (G) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays and can obtain the above-mentioned effects and the above-mentioned optical properties, adhesion properties, etc., and can be any one of a monomer, an oligomer or a polymer, or a mixture thereof. Among them, monofunctional acrylate monomers and multifunctional acrylate monomers can be preferably listed. From the perspective of the obtained adhesive maintaining the above-mentioned optical properties, adhesion properties, etc. while also exerting excellent adhesion, durability, etc., multifunctional acrylate monomers are preferred. From the perspective of compatibility with the adhesive component, especially the (meth)acrylate polymer (A), or the perspective of the dispersibility of the coloring component and the light diffusion component in the adhesive, the multifunctional acrylate monomer is preferably a substance with a molecular weight of less than 1000.

[0163] As the multifunctional acrylate monomer, preferably a difunctional, trifunctional, tetrafunctional, pentafunctional, or hexafunctional acrylate monomer is used. Among these, from the perspective of dispersibility of the coloring component and light-diffusing component in the adhesive, preferably, a multifunctional acrylate monomer containing an isocyanurate structure in the molecule, such as di(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)isocyanurate, or ε-caprolactone-modified tris-(2-(meth)acryloyloxyethyl)isocyanurate, or a multifunctional acrylate monomer containing a cyclic structure (particularly a cycloalkane structure) in the molecule, such as tricyclodecane dimethanol (meth)acrylate is used. These monomers may be used alone or in combination of two or more.

[0164] From the perspective of durability, the content of the active energy ray-curable component (G) in the adhesive composition P is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 35 parts by mass, and even more preferably 1 to 20 parts by mass per 100 parts by mass of the (meth)acrylate polymer (A). On the other hand, from the perspective of achieving both good dispersibility of the coloring component and the light-diffusing component, the content is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 6 parts by mass.

[0165] (2.2.10. Photopolymerization initiator (H))

[0166] When ultraviolet rays are used as the active energy rays for curing the adhesive composition P, it is preferred that the adhesive composition P further contain a photopolymerization initiator (H) in addition to the active energy ray-curable component (G). This allows efficient polymerization of the active energy ray-curable component (G) while reducing the polymerization curing time and the irradiation dose of active energy rays.

[0167] Examples of the photopolymerization initiator (H) 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-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, and p-phenylenediol. Ketone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, 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, etc. These photopolymerization initiators may be used alone or in combination of two or more.

[0168] Among the above, from the perspective of being easy to decompose when irradiated with ultraviolet light and being easy to reliably cure the adhesive, a phosphine oxide-based photopolymerization initiator is preferred. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. are preferred. Among the optical components as adherends, although there are also components with ultraviolet light concealing properties, even when irradiated with ultraviolet light through such ultraviolet light concealing components that are difficult for ultraviolet light to pass, as long as the above-mentioned phosphine oxide-based photopolymerization initiator is used, curing of the active energy ray curable component (G) can be performed.

[0169] The content of the photopolymerization initiator (H) in the 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 16 parts by mass, relative to 100 parts by mass of the active energy ray-curable component (G).

[0170] (2.3. Preparation of Adhesive Composition)

[0171] The adhesive composition P can be prepared, for example, by first preparing a (meth)acrylate polymer (A), then mixing the obtained (meth)acrylate polymer (A), a crosslinking agent (B), and, if necessary, a coloring component (C) and a light-diffusing component (D). Furthermore, a silane coupling agent (E), an antistatic agent (F), an active energy ray-curable component (G), and a photopolymerization initiator (H) may be added.

[0172] When there are two or more adhesive layers, adhesive compositions for forming each adhesive layer may be prepared separately. In this case, the coloring component (C) and the light diffusing component (D) may be blended so as to be contained in at least one adhesive composition.

[0173] The (meth)acrylate polymer (A) can be prepared, for example, by polymerizing a mixture of monomers constituting the polymer using a conventional free radical polymerization method. The polymerization of the (meth)acrylate polymer (A) can be carried out using a solution polymerization method using a polymerization initiator as needed. By using a solution polymerization method to polymerize the (meth)acrylate polymer (A), it is easier to increase the molecular weight of the resulting polymer and adjust the molecular weight distribution, thereby further reducing the formation of low molecular weight products.

[0174] Examples of the polymerization solvent used in the solution polymerization method include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone. A single polymerization solvent may be used, or two or more may be used simultaneously. Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more may be used simultaneously. Furthermore, in the polymerization step, the weight-average molecular weight of the resulting polymer may be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

[0175] Next, a crosslinking agent (B), a coloring component (C) as needed, and a light-diffusing component (D) are added to the resulting solution of the (meth)acrylate polymer (A), and the mixture is thoroughly mixed to obtain an adhesive composition P (coating solution) diluted with a solvent. Furthermore, a silane coupling agent (E), an antistatic agent (F), an active energy ray-curable component (G), and a photopolymerization initiator (H) may be added.

[0176] When any of the above components is a solid component or a component that precipitates when mixed with other components in an undiluted state, the component may be dissolved or diluted in a diluting solvent before mixing with the other components.

[0177] Examples of the diluent solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0178] The concentration and viscosity of the prepared coating solution can be appropriately selected according to the conditions as long as they are within the range that can be applied. For example, the adhesive composition P is diluted so that the concentration is 10 to 60% by mass. In addition, when obtaining the coating solution, it is not necessary to add a dilution solvent. As long as the adhesive composition P has a viscosity that can be applied, no dilution solvent may be added. In this case, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is directly used as the dilution solvent.

[0179] (2.4. Preparation of Adhesive)

[0180] The adhesive constituting the adhesive layer is preferably obtained by crosslinking the adhesive composition P. Crosslinking of the adhesive composition P can generally be performed by heat treatment. Alternatively, the drying process for volatilizing the diluting solvent or the like from the film of the adhesive composition P applied to the desired object may also serve as the heat treatment.

[0181] The heating temperature of the heat treatment is preferably 50 to 150° C., more preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

[0182] After the heat treatment, an aging period of approximately 1 to 2 weeks at room temperature (e.g., 23°C, 50% relative humidity (RH)) may be provided as needed. If aging is required, a cross-linked adhesive can be obtained after the aging period. If aging is not required, a cross-linked adhesive can be obtained after the heat treatment is completed.

[0183] (2.5. Peel Sheet)

[0184] The release sheets 20a and 12b protect the adhesive layer 11 until the adhesive sheet 1 is used, and are peeled off when the adhesive sheet 1 (adhesive layer 10) is used. In the adhesive sheet 1 of this embodiment, one or both of the release sheets 20a and 20b are not essential.

[0185] As the release sheets 20a and 20b, for example, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. can be used. In addition, cross-linked films of these release films can also be used. Furthermore, laminated films of these release films can also be used.

[0186] The release surfaces of the release sheets 20a and 20b (particularly the surface in contact with the adhesive layer 10) are preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Furthermore, the release force of one release sheet 20a and 20b is preferably smaller than that of the other release sheet.

[0187] The thickness of the release sheets 20a and 20b is not particularly limited, but is generally about 20 to 150 μm.

[0188] (2.6. Production of Adhesive Sheet)

[0189] There is no particular limitation on the method for manufacturing the adhesive sheet 1, but it can be manufactured by a known method. For example, a coating liquid of the adhesive composition P is applied to the release surface of a first release sheet 20a (or a second release sheet 20b), and the adhesive composition P is cross-linked by heat treatment to form a coating layer with a specified thickness. The release surface of another second release sheet 20b (or the first release sheet 20a) is overlapped on the formed coating layer. When aging is required, after a specified aging period, the coating layer becomes the adhesive layer 10. In addition, when aging is not required, the coating layer directly becomes the adhesive layer 10. Thus, an adhesive sheet 1 having a single-layer adhesive layer can be obtained.

[0190] When the adhesive layer is two layers, for example, a coating liquid of an adhesive composition P for forming one adhesive layer (e.g., the first adhesive layer 11) is applied to the release surface of one release sheet, and a heat treatment is performed to crosslink the adhesive composition to form a coating layer, thereby obtaining a release sheet with a coating layer. Furthermore, a coating liquid of an adhesive composition P for forming another adhesive layer (e.g., the second adhesive layer 12) is applied to the release surface of another release sheet, and a heat treatment is performed to crosslink the adhesive composition to form a coating layer, thereby obtaining a release sheet with a coating layer. Subsequently, the release sheet with a coating layer is bonded to the release sheet with a coating layer so that the two coating layers are in contact with each other.

[0191] When the adhesive layer has three or more layers, a plurality of release sheets with coating layers may be prepared, and the coating layers may be laminated in a desired number and in a desired lamination order.

[0192] When aging is required, the coating layer becomes the adhesive layer after a predetermined aging period. Otherwise, when aging is not required, the coating layer directly becomes the adhesive layer. Thus, an adhesive sheet 1 having multiple adhesive layers is obtained.

[0193] Examples of a method for applying the coating liquid of the adhesive composition P include a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.

[0194] (3. Laminated body)

[0195] like Figure 2 As shown, the stacked body 3 of this embodiment is composed of a first component 31 (a display component), a second component 32 (another display component), and an adhesive layer 10, wherein the adhesive layer 10 is located between the first component 31 and the second component 32 and adheres the first component 31 and the second component 32 to each other.

[0196] The adhesive layer 10 in the laminate 3 is the adhesive layer 10 of the adhesive sheet 1 described above.

[0197] The laminate 3 is the display itself or a component that constitutes a portion of the display. Examples of the display include organic electroluminescent (OLED) displays, electrophoretic displays (electronic paper), liquid crystal displays using plastic substrates (films) as substrates, and foldable displays. These may include touch panels for position input tools.

[0198] An example of manufacturing the laminated body 3 is shown. First, one release sheet 20 b of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 10 of the adhesive sheet 1 is attached to one surface of the first member 31 .

[0199] Then, another release sheet 20a is peeled off from the adhesive layer 10 of the adhesive sheet 1, and the exposed adhesive layer 10 of the adhesive sheet 1 is bonded to the second member 32 to obtain the laminate 3. As another example, the order of bonding the first member 31 and the second member 32 may be reversed.

[0200] When the adhesive layer 10 is active energy ray-curable, after the adhesive layer 10, the first member 31, and the second member 32 are bonded together, the adhesive layer 10 is irradiated with active energy rays. This polymerizes the active energy ray-curable component (G) in the adhesive layer 10, thereby obtaining a laminate 2 in which the adhesive layer 10 is cured.

[0201] (4. Display body)

[0202] The display of this embodiment includes the above-mentioned laminate 3. It may be composed solely of the laminate 3 or may include one or more laminates 3 and other components. When laminating one laminate 3 with another laminate 3, or laminating a laminate 3 with another component, the lamination is preferably performed via the adhesive layer 10 of the adhesive sheet 1.

[0203] A touch panel as an example of a display body of this embodiment is shown in FIG. Figure 3 .like Figure 3As shown, the touch panel 5 of this embodiment includes a display module 51, a first film sensor 52 laminated thereon via an adhesive layer 61, a second film sensor 53 laminated thereon via an adhesive layer 62, and a cover material 54 laminated thereon via an adhesive layer 63.

[0204] Preferably, at least one of the three adhesive layers 61 to 63 in the touch panel 5 is the adhesive layer 10 of the adhesive sheet 1 of this embodiment, and most preferably, all of the adhesive layers 61 to 63 are the adhesive layers 10 of the adhesive sheet 1 of this embodiment.

[0205] Examples of the display module 51 include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

[0206] The first film sensor 52 and the second film sensor 53 are generally composed of respective base films 55 and patterned transparent conductive films 56. The base film 55 is not particularly limited, but for example, polyethylene terephthalate film, polycarbonate film, polymethyl methacrylate film, polycycloolefin film, polyolefin film, triacetyl cellulose film, etc. can be used.

[0207] As the transparent conductive film 56, for example, there can be listed metals such as platinum, gold, silver, and copper; oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc dioxide; composite oxides such as tin-doped indium oxide (ITO), zinc oxide-doped indium oxide, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide; and non-oxidizing compounds such as chalcogenides, lanthanum hexaboride, titanium nitride, and titanium carbide, and it is particularly preferred that it is composed of tin-doped indium oxide (ITO).

[0208] The cover material 54 is generally composed primarily of a glass plate or a plastic plate. The glass plate is not particularly limited, but examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate glass. The plastic plate is not particularly limited, but examples thereof include acrylic plates made of polymethyl methacrylate and the like, and polycarbonate plates.

[0209] Furthermore, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on one or both surfaces of the glass plate or plastic plate, or an optical member such as a hard coat layer, an antireflection layer, or an antiglare layer may be laminated.

[0210] In this embodiment, the cover material 54 has a step on the adhesive layer 10 side, specifically, a step due to the presence or absence of the printed layer 57. The printed layer 57 is generally formed on the adhesive layer 10 side of the cover material 54 in a frame shape.

[0211] The material constituting the printed layer 57 is not particularly limited, and known materials for printing can be used. The thickness of the printed layer 57, i.e., the height of the step, is preferably 3 to 45 μm, more preferably 5 to 35 μm, further preferably 7 to 25 μm, and particularly preferably 7 to 15 μm.

[0212] The touch panel 5 has various components bonded together via the adhesive layer, and thus has both seamlessness and concealment, and thus has excellent visibility and design as a display.

[0213] Another example of the display of this embodiment is shown in Figure 4 .like Figure 4 As shown, the display 7 of this embodiment comprises a substrate 71 (backlight element 70) having a plurality of light-emitting elements 72, an adhesive layer 81 laminated on the substrate 71, and a display portion 73. This display is a display having a direct-type backlight element. Preferably, the adhesive layer 81 in the display 7 is the adhesive layer 10 of the adhesive sheet 1 of this embodiment.

[0214] Examples of the display 7 include a liquid crystal display (LCD), a light emitting diode (LED) display, and an organic electroluminescent (organic EL) display. The display may also be a touch panel. Among these, a liquid crystal display (liquid crystal display device) is preferred, as it requires a backlight element.

[0215] The backlight element 70 is composed of one or more substrates 71 and a plurality of light-emitting bodies 72 arranged on the substrates. The backlight element 70 has unevenness caused by the plurality of light-emitting bodies 72. Preferably, these unevenness are directly embedded by the adhesive layer 81 of this embodiment. On the other hand, when these unevenness are already embedded in the sealing resin, they are preferably laminated on the sealing resin. In the former case, the adhesive layer 81 not only embeds the unevenness well but also exhibits seamlessness and concealment. In the latter case, the adhesive layer 81 is well laminated while exhibiting seamlessness and concealment.

[0216] The substrate 71 is not particularly limited, but a substrate commonly used in backlight devices can be used. The substrate 71 is generally a printed circuit board (PCB).

[0217] The substrate 71 may be integrally formed so as to carry a plurality of light-emitting bodies 72 together, or may be separately formed so as to carry a single light-emitting body 72 on each substrate 71. In the case of separate formation, each substrate 71 is usually fixed to a frame, a support, a housing, etc. In this embodiment, from the perspective of reducing the thickness of the display body 7 or simplifying the display body manufacturing process, it is preferred to integrally form the substrate 71 so as to carry a plurality of light-emitting bodies 72 together.

[0218] A reflective layer or a reflective member may be formed on the adhesive layer 81 side surface of the substrate 71. This effectively increases the brightness of the backlight element 70. Known materials can be used for the reflective layer and the reflective member.

[0219] Examples of the light emitting body 72 include light emitting diodes (LEDs), laser diodes (LDs), organic electroluminescent elements, and inorganic electroluminescent elements. Among them, LEDs are preferred, and mini-LEDs or micro-LEDs are particularly preferred, from the perspective of embedding the unevenness formed by the adhesive layer 81 .

[0220] The thickness of the light emitting body 72 is preferably 1 to 1000 μm, more preferably 10 to 700 μm, particularly preferably 20 to 400 μm, further preferably 30 to 300 μm, and particularly preferably 40 to 200 μm.

[0221] The width of the gap between adjacent light emitters 72 is preferably 0.01 to 100 mm, particularly preferably 0.1 to 10 mm, further preferably 0.3 to 4 mm, and even more preferably 0.5 to 2 mm.

[0222] The shape of the luminous body 72 is not particularly limited, but is generally a rectangular parallelepiped, hemispherical, etc. The size of the luminous body 72 is not particularly limited, but from the perspective of luminous body embedding properties, a side or diameter in a plan view is preferably 0.01 to 100 mm, more preferably 0.1 to 10 mm, particularly preferably 0.2 to 5 mm, and even more preferably 0.5 to 2 mm.

[0223] Since the display body 7 is formed by laminating with the adhesive layer 81, it has both seamlessness and concealment, and thus has excellent visibility and design properties as a display body.

[0224] In this specification, the phrase "X to Y" (X and Y are arbitrary numbers) includes, unless otherwise specified, the meaning of "X or greater and Y or less," and also includes the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, the phrase "X or greater" (X is an arbitrary number) includes, unless otherwise specified, the meaning of "preferably greater than X," and the phrase "Y or less" (Y is an arbitrary number) includes, unless otherwise specified, the meaning of "preferably less than Y."

[0225] While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways within the scope of the present invention.

[0226] Example

[0227] (Example 1)

[0228] 1. Preparation of (meth)acrylate polymers

[0229] 27.5 parts by mass of n-butyl acrylate, 27.5 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of N-acryloylmorpholine, 15 parts by mass of isobornyl acrylate, and 25 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylate polymer (A). The molecular weight of the obtained (meth)acrylate polymer (A) was measured by the method shown below, and the weight average molecular weight (Mw) was 500,000.

[0230] The weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

[0231] (Measurement conditions)

[0232] GPC measurement apparatus: HLC-8020 manufactured by Tosoh Corporation

[0233] GPC columns (passed in the following order): manufactured by Tosoh Corporation

[0234] TSK guard column HXL-H

[0235] TSK gel GMHXL (×2)

[0236] TSK gel G2000HXL

[0237] ·Test solvent: tetrahydrofuran

[0238] ·Measurement temperature: 40℃

[0239] 2. Preparation of Adhesive Composition A

[0240] 100 parts by mass of the (meth)acrylate polymer (A) obtained above (solid content conversion value; the same below) was mixed with 0.15 parts by mass of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E") as a crosslinking agent (B), 0.26 parts by mass of a black pigment as a coloring component (C), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (E), and the mixture was thoroughly stirred and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition A.

[0241] 3. Preparation of Adhesive Composition B

[0242] 100 parts by mass (solid content conversion) of the (meth)acrylate polymer (A) obtained above, 0.15 parts by mass of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E") as a crosslinking agent (B), 2 parts by mass of microparticles composed of a silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "TOSPEARL 145", shape: spherical, average particle size: 4.5 μm, refractive index: 1.43) as a light diffusion component (D), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (E) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition B.

[0243] 4. Manufacturing of adhesive sheets

[0244] The resulting coating solution of adhesive composition A was applied using a doctor blade coating method onto the release-treated surface of a release sheet 1, one side of which was release-treated with a silicone release agent. The coating layer was then heat-treated at 90°C for 1 minute to induce a crosslinking reaction, forming a coating layer A.

[0245] Next, the coating layer A on the release sheet 1 obtained above was laminated so that the release-treated surface of the release sheet 2, made of a polyethylene terephthalate film with a release treatment on one side using a silicone release agent, came into contact with the coating layer A. The laminate was aged for 7 days under conditions of 23°C and 50% RH to produce a laminate having a 50 μm thick adhesive layer A. The release force of the release sheet 1 was greater than that of the release sheet 2.

[0246] Next, using a knife coater, the resulting coating solution of adhesive composition B was applied to the release-treated surface of a release sheet 3, one side of which was release-treated with a silicone release agent. The coating layer was then heat-treated at 90°C for 1 minute to induce a crosslinking reaction, forming coating layer B.

[0247] Next, the coating layer A on the release sheet 3 obtained above was laminated so that the release-treated surface of the release sheet 4, made of a polyethylene terephthalate film with a release treatment on one side using a silicone release agent, came into contact with the coating layer A. The laminate was aged for 7 days under conditions of 23°C and 50% RH to produce a laminate having a 50 μm thick adhesive layer B. The release force of the release sheet 3 was greater than that of the release sheet 4.

[0248] The release sheet 2 is peeled off from the laminate having the adhesive layer A to expose the adhesive layer A. Next, the release sheet 4 is peeled off from the laminate having the adhesive layer B to expose the adhesive layer B.

[0249] The exposed main surface of the adhesive layer A and the exposed main surface of the adhesive layer B were bonded together to obtain an adhesive sheet in which the adhesive layer A and the adhesive layer B were laminated in contact with each other and sandwiched between two release sheets.

[0250] The thickness of the adhesive layer is a value measured using a constant pressure thickness gauge (PG-02, manufactured by TECLOCK Co., Ltd.) in accordance with JIS K7130.

[0251] (Examples 2 to 15, Comparative Examples 1 to 4)

[0252] The adhesive layer A was manufactured by the same method as in Example 1, except that the composition and molecular weight of the (meth)acrylate polymer (A), the type and amount of the crosslinking agent (B), the type and amount of the coloring component (C), the type and amount of the light diffusion component (D), the amount of the silane coupling agent (E), the amount of the antistatic agent (F), the amount of the active energy ray-curable component (G), the amount of the photopolymerization initiator (H), and the thickness of the adhesive layer A were changed as shown in Table 1.

[0253] Separately, an adhesive layer B was produced in the same manner as in Example 1, except that the composition and molecular weight of the (meth)acrylate polymer (A), the type and amount of the crosslinking agent (B), the type and amount of the coloring component (C), the type and amount of the light-diffusing component (D), the amount of the silane coupling agent (E), the amount of the antistatic agent (F), the amount of the active energy ray-curable component (G), the amount of the photopolymerization initiator (H), and the thickness of the adhesive layer B were changed as shown in Table 2. In Example 6, no adhesive layer B was produced.

[0254] Using the prepared adhesive layer A and adhesive layer B, adhesive sheets were prepared in the same manner as in Example 1. The adhesive sheets of Examples 1 to 5, 7 to 15, and Comparative Examples 1 to 4 had two adhesive layers, while the adhesive sheet of Example 6 had a single adhesive layer (one layer).

[0255] In Tables 1 and 2, the amounts of the crosslinking agent (B), coloring component (C), light diffusing component (D), silane coupling agent (E), antistatic agent (F), active energy ray-curable component (G), and photopolymerization initiator (H) added are relative to 100 parts by mass (solid content conversion) of the (meth)acrylate polymer (A).

[0256] [Table 1]

[0257]

[0258] [Table 2]

[0259]

[0260] The details of the abbreviations listed in Tables 1 and 2 are as follows. Regarding the coloring component (C), the optical properties of solutions prepared by diluting the coloring components C1 and C2 listed in Tables 1 and 2 10,000 times with ethyl acetate are shown in Table 3. The optical properties shown in Table 3 were calculated based on the haze values ​​(%) measured on the diluted solutions using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000. The haze difference 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 of the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm. The standard deviation of the haze value is the standard deviation of the haze value at each 5 nm interval in the wavelength range of 380 nm to 780 nm.

[0261] ((Meth)acrylate copolymer (A))

[0262] BA: n-butyl acrylate

[0263] 2EHA: 2-ethylhexyl acrylate

[0264] ACMO: N-acryloylmorpholine

[0265] IBXA: Isobornyl acrylate

[0266] HEA: 2-Hydroxyethyl Acrylate

[0267] PhEA: 2-Phenoxyethyl acrylate

[0268] 4HBA: 4-Hydroxybutyl acrylate

[0269] AA: Acrylic acid

[0270] (Crosslinking agent (B))

[0271] B1: Isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E")

[0272] B2: 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane

[0273] (Coloring ingredient (C))

[0274] C1, C2: Carbon black pigments

[0275] (Light diffusion component (D))

[0276] D1: Microparticles composed of silicone resin (a silicon-containing compound with an intermediate structure between inorganic and organic) (Momentive Performance Materials Japan, product name "TOSPEARL 145," shape: spherical, average particle size: 4.5 μm, refractive index: 1.43)

[0277] D2: Spherical polymethyl methacrylate-polystyrene copolymer microparticles (manufactured by Sekisui Kasei Co., Ltd., product name "XX-17LA", average particle size: 3 μm, refractive index: 1.56)

[0278] (Silane coupling agent (E))

[0279] E1: 3-glycidoxypropyltrimethoxysilane

[0280] (Antistatic agent (F))

[0281] F1: Onium salt antistatic agent (manufactured by DKS Co. Ltd., product name "AS-804")

[0282] (Active energy ray-curable component (G))

[0283] G1: ε-caprolactone-modified tris-(2-acryloyloxyethyl) isocyanurate (manufactured by SHIN-NAKAMURA CHEMICALCO, LTD., product name "NK ESTER A-9300-1CL")

[0284] (Photopolymerization initiator (H))

[0285] H1: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide

[0286] [Table 3]

[0287] Table 3

[0288]

[0289] (Lightness L*, chromaticity a*, and chromaticity b* of the adhesive layer)

[0290] The lightness L*, chromaticity a*, and chromaticity b* of the adhesive layer A-side surfaces of the adhesive sheets obtained in the Examples and Comparative Examples were measured using a simultaneous spectrophotometric colorimeter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "SQ2000") according to the CIE 1976 L*a*b* colorimetric system. The results are shown in Table 4.

[0291] (Evaluation of Gel Fraction of Adhesive)

[0292] The adhesive layers produced in the Examples and Comparative Examples were cut into 80 mm x 80 mm pieces. The colored adhesive layers were wrapped in a polyester mesh (product name: Tetron Mesh #200) and weighed using a precision balance. The mass of the mesh alone was subtracted from the weight to calculate the mass of the adhesive alone. This mass was recorded as M1.

[0293] Next, at room temperature (23°C), the adhesive wrapped in the polyester mesh is immersed in ethyl acetate for 24 hours. Then, the mesh is taken out and air-dried for 24 hours 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 is weighed with a precision balance. The mass of the adhesive itself is calculated by subtracting the mass of the mesh alone from the weighed value. The mass at this time is recorded as M2. Using the obtained M1 and M2, the gel fraction is calculated according to the following formula. The results are shown in Table 4.

[0294] Gel fraction (%) = (M2 / M1) × 100

[0295] The adhesive sheet of Example 7 was irradiated with active energy rays (ultraviolet rays; UV) through a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "iupilon-sheet MR58U," thickness: 0.7 mm, containing a UV absorber) comprising a polymethyl methacrylate resin (PMMA) layer laminated on a polycarbonate resin (PC) sheet. The gel fraction was measured before and after irradiation using the same method as above. The irradiation conditions for the active energy rays are shown below.

[0296] <Active Energy Ray Irradiation Conditions>

[0297] Use high-pressure mercury lamp

[0298] Illumination 200mW / cm 2 , light intensity 2000mJ / cm 2

[0299] The UV illuminance and light meter used was the UVPF-A1 manufactured by Eye Graphics Co., Ltd.

[0300] (Measurement of Adhesive Strength of Adhesive Layer)

[0301] Release sheet 3 was removed from the adhesive sheets obtained in the Examples and Comparative Examples, and the exposed adhesive layer B was bonded to the adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "PETA4300," thickness: 100 μm) having an adhesive layer. This resulted in a laminate of release sheet 1 / adhesive layer A / adhesive layer B / PET film. The resulting laminate was cut into pieces 25 mm wide and 100 mm long to prepare a sample.

[0302] At 23°C and 50% relative humidity, the release sheet 1 was peeled off from the sample, and the exposed adhesive layer A was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The sample was then pressurized at 0.5 MPa and 50°C for 20 minutes using an autoclave manufactured by Kurihara Manufactory Co., Ltd. After standing for 24 hours at 23°C and 50% relative humidity, the adhesive strength (N / 25 mm) was measured using a tensile testing machine (manufactured by ORIENTEC CORPORATION, product name "TENSILON") at a peel speed of 300 mm / min and a peel angle of 180 degrees. Conditions not described here were measured in accordance with JIS Z0237:2009. The results are shown in Table 4.

[0303] The adhesive sheet of Example 7 was irradiated with active energy rays (ultraviolet rays; UV) through the plastic plate in the same manner as for the gel fraction measurement, and the adhesive strength before and after irradiation was measured in the same manner as above. The active energy ray irradiation conditions were the same as described above.

[0304] (Determination of total light transmittance)

[0305] The adhesive layer A of the adhesive sheet obtained in the Examples and Comparative Examples was bonded to glass to serve as a measurement sample. After background measurement using the glass, the total light transmittance (%) of the measurement sample was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH-5000") in accordance with JIS K7361-1:1997. The results are shown in Table 4.

[0306] (Determination of Haze Value)

[0307] The haze values ​​(%) of the adhesive layers of the adhesive sheets obtained in Examples and Comparative Examples were measured from the adhesive layer A side using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH-5000") in accordance with JIS K7136:2000. The obtained haze values ​​(%) are shown in Table 4.

[0308] (Evaluation of screen design: seamlessness)

[0309] The adhesive sheets obtained in the Examples and Comparative Examples were cut into 70 mm long by 70 mm wide. The adhesive layers of the adhesive sheets were sandwiched between two sheets of soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd., 70 mm long by 70 mm wide by 1.1 mm thick) to form a laminated product. This was used as a sample. For the adhesive sheet of Example 7, after the laminated product was obtained, the plastic plate used in the gel fraction evaluation was placed on the soda-lime glass. Active energy rays (ultraviolet rays; UV) were irradiated through the plastic plate and the soda-lime glass. The adhesive layer after active energy ray irradiation was used as a sample. The active energy ray irradiation conditions were as described above.

[0310] The resulting sample was placed directly in front of a monitor (Fujitsu Limited, product name "LITEBOOK A574 / H," 15.6 inches, 1366×768 resolution) with the lights off. The sample was placed so that its perimeter was adjacent to the monitor's frame. The visual appearance of the boundary with the frame was visually assessed, and the design quality was evaluated for seamlessness using the following criteria. The results are shown in Table 4.

[0311] A: Unable to visually identify the boundary

[0312] B: The boundary is slightly discernible, but not obvious

[0313] F: The boundary can be clearly identified visually

[0314] (Evaluation of screen design: screen color tone)

[0315] The sample was placed so that its surrounding area was adjacent to the frame of the display. The sample's color tone (black and white) was visually assessed under a three-wavelength fluorescent lamp (200 cm from the lamp). The design quality of the screen's color tone was evaluated using the following criteria. The results are shown in Table 4.

[0316] A: Deep black under fluorescent light

[0317] B: White can be seen under fluorescent light, but the degree of black is large.

[0318] C: White is visible under fluorescent light, with little black.

[0319] F: Under fluorescent light, the overall whiteness can be seen, and no blackness can be felt.

[0320] (concealment)

[0321] A white paper with characters of the following two sizes printed in black was placed 3 cm away from the sample surface.

[0322] 1: Font size: 16pt, font: Ms Gothic, text: リンテック

[0323] 2: Font size: 8pt, font: Ms Gothic, text: リンテック

[0324] The characters were observed from the adhesive layer side, and whether or not the characters were visually recognizable was evaluated based on the following criteria. The results are shown in Table 4.

[0325] A: Can visually identify 1, but not 2

[0326] B: Able to visually identify 1, but difficult to visually identify 2

[0327] F1: Both 1 and 2 can be easily visually identified

[0328] F2: Both 1 and 2 cannot be visually identified

[0329] (Concave-convex embedding property)

[0330] A glass plate (manufactured by Nippon Sheet Glass Co., Ltd., material: soda-lime glass, 182 mm long x 112 mm wide x 1.1 mm thick) was screen-printed with a thermosetting ink (manufactured by Seiko Advance Ltd., product name "HS-GC3M3066 Black") in a cross pattern (25 mm long x 25 mm wide, 7 mm wide). The thermosetting ink was then cured by heating (temperature: 120°C, 30 minutes) to produce a glass plate with stepped prints (step height: 15 μm, 20 μm, 25 μm, 40 μm, or 50 μm).

[0331] The release sheet is peeled off from the adhesive sheet manufactured in the examples and comparative examples, and the exposed adhesive layer A is attached to the easy-adhesive layer of a polyethylene terephthalate film (manufactured by TOYOBO CO., LTD., product name "COSMOSHINE A4160", thickness: 100 μm) having an easy-adhesive layer. Then, the release sheet is peeled off to reveal the adhesive layer. Next, the above-mentioned laminate is laminated on each glass plate with a step difference using a laminator (manufactured by FUJIPLA Inc., product name "LPD3214") in such a way that the adhesive layer covers the entire cross-shaped printing. Furthermore, after performing a heat treatment at 50°C and 0.5 MPa for 30 minutes, it is placed at normal pressure, 23°C, and a relative humidity of 50% for 24 hours to serve as an evaluation sample. In Example 7, the plastic plate used in the gel fraction evaluation was further stacked on soda-lime glass. Active energy rays (ultraviolet rays; UV) were irradiated through the plastic plate and soda-lime glass to prepare evaluation samples. The active energy ray irradiation conditions were the same as those described above.

[0332] Next, the evaluation sample was stored under high temperature and high humidity conditions of 85°C and 85% relative humidity for 72 hours (durability test) to evaluate the concave-convex embedding property. The concave-convex embedding property is judged by whether the adhesive layer completely embeds the printed step difference (concave-convex). When bubbles, floating, peeling, etc. are observed at the interface between the printed step difference and the adhesive layer, it is judged that the adhesive layer does not embed the printed step difference (concave-convex). Among them, the concave-convex embedding property is calculated by the concave-convex embedding rate (%) shown in the following formula and evaluated according to the following benchmarks. The results are shown in Table 4.

[0333] Concave-convex embedding rate (%) = {(height of the step that remains embedded without bubbles, floating, peeling, etc. after the durability test (μm)) / (thickness of the adhesive layer (μm)}×100

[0334] <Evaluation criteria for uneven embedding properties>

[0335] ◎…Concave and convex embedding rate is more than 30%

[0336] ○…The concave-convex embedding rate is less than 30% and is 20% or more

[0337] ×…Concave and convex embedding rate is less than 20%

[0338] [Table 4]

[0339]

[0340] From Table 4, it can be confirmed that the adhesive sheets of Examples 1 to 15 have both seamlessness and concealing properties.

[0341] Industrial Applicability

[0342] The adhesive sheet of the present invention is suitably used for laminating members constituting a display, for example.

[0343] Description of Reference Numerals

[0344] 1: Adhesive sheet; 10: Adhesive layer; 11: First adhesive layer; 12: Second adhesive layer; 20a, 20b: Release sheet; 3: Laminated body; 31: First component; 32: Second component; 5: Touch panel; 51: Display module; 52: First film sensor; 53: Second film sensor; 54: Covering material; 55: Base film; 56: Transparent conductive film; 57: Printed layer; 61, 62, 63: Adhesive layer; 7: Display; 70: Backlight element; 71: Substrate; 72: Light-emitting body; 73: Display unit; 81: Adhesive layer.

Claims

1. An adhesive sheet having an adhesive layer for bonding a first member and a second member, wherein: The adhesive layer comprises an adhesive component, a coloring component and a light diffusion component, The total light transmittance of the adhesive layer is greater than or equal to 5% and less than or equal to 95%.

2. The adhesive sheet according to claim 1, wherein The adhesive layer is composed of two or more layers.

3. The adhesive sheet according to claim 1, wherein The adhesive layer is a single layer.

4. The adhesive sheet according to any one of claims 1 to 3, wherein The adhesive layer has a haze value of 5% or more and 99.9% or less.

5. The adhesive sheet according to any one of claims 1 to 3, wherein The light diffusion component is light diffusion particles.

6. The adhesive sheet according to any one of claims 1 to 3, wherein The adhesive component is an acrylic adhesive component.

7. A laminate comprising a first member, a second member, and an adhesive layer for bonding the first member and the second member to each other, wherein: The adhesive layer is an adhesive layer included in the adhesive sheet according to any one of claims 1 to 3. A display comprising the laminate according to claim 7 .

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