Optical laminates and devices

Abstract

To provide an optical laminate used in devices such as displays, in which the occurrence of marks caused by deformation due to localized loads is suppressed. [Solution] An optical laminate in which a first member, a first adhesive layer, an intermediate layer, a second adhesive layer, and a second member are laminated in this order, wherein the hardness of the surface of the first member, as measured by an E-type durometer, is 96 or higher.

Description

Technical Field

[0001] The present invention relates to an optical laminate and a device.

Background Art

[0002] A display member having a liquid crystal element, a light emitting diode (LED) element, an organic electroluminescence (organic EL) element, etc. is laminated with another member (for example, a protective panel for protecting the display member) to constitute a display (display) of a device such as an electronic device.

[0003] Such a laminate of a display member and another member is generally formed by bonding the display member and another member using an adhesive layer of an adhesive sheet.

[0004] In recent years, as a display of an electronic device, a bendable display, so-called a flexible display, has been proposed. The flexible display is expected to have a wide range of applications, for example, for a stationary display installed on a cylindrical column by bending, or for a mobile display that can be carried by being folded or rolled up.

[0005] Examples of the flexible display include an organic electroluminescence (organic EL) display, an electrophoretic display (electronic paper), a liquid crystal display using a plastic film as a substrate, etc.

[0006] Examples of such a flexible display include a display that is bent during molding and maintains a bent state, a display that is repeatedly bent during use, etc.

[0007] Patent Document 1 discloses an optical laminate comprising a glass plate, an adhesive layer, and an optical member, and discloses that this optical laminate exhibits excellent impact resistance and bending resistance. Patent Document 2 discloses a flexible image display device comprising a window member, an optical film or touch sensor, and a panel member laminated via multiple adhesive members, and discloses that this flexible image display device can ensure high pencil hardness and high adhesion to repeated bending in high-temperature environments. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-7904 [Patent Document 2] Patent No. 6934996 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, Patent Documents 1 and 2 had the problem that they did not evaluate whether marks actually form when a localized load is applied to the surface of an optical laminate or a flexible image display device.

[0010] This invention has been made in view of the above circumstances, and aims to provide an optical laminate used in devices such as displays, in which the occurrence of marks caused by deformation due to localized loads is suppressed. [Means for solving the problem]

[0011] The embodiments of the present invention are as follows.

[0012] [1] An optical laminate in which a first member, a first adhesive layer, an intermediate layer, a second adhesive layer, and a second member are laminated in this order, The optical laminate is such that the hardness of the surface of the first component, as measured by an E-type durometer, is 96 or higher.

[0013] [2] The optical laminate is the optical laminate described in [1], wherein the optical laminate is bendable in the direction in which compressive stress is generated in the first member.

[0014] [3] The optical laminate according to [1] or [2], wherein the ratio (G'1 / G'2) of the storage modulus G'1 of the first adhesive constituting the first adhesive layer at 25°C to the storage modulus G'2 of the second adhesive constituting the second adhesive layer at 25°C is less than 0.133.

[0015] [4] An optical laminate according to any one of [1] to [3], wherein the ratio (tanδ1 / tanδ2) of the loss tangent tanδ1 of the first adhesive constituting the first adhesive layer at 25°C to the loss tangent tanδ2 of the second adhesive constituting the second adhesive layer at 25°C is greater than 1.1.

[0016] [5] An optical laminate according to any of [1] to [4], wherein the thickness of the optical laminate is 5 μm or more and 2500 μm or less.

[0017] [6] An optical laminate according to any one of [1] to [5], wherein the thickness of the first adhesive layer is 1 μm or more and 500 μm or less.

[0018] [7] An optical laminate according to any one of [1] to [6], wherein the thickness of the second adhesive layer is 1 μm or more and 500 μm or less.

[0019] The device comprises an optical laminate as described in any of [8], [1] to [7]. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide an optical laminate used in devices such as displays, in which the occurrence of marks caused by deformation due to localized loads is suppressed. [Brief explanation of the drawing]

[0021] [Figure 1] FIG. 1 is a cross-sectional view of an optical laminate according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a device according to an embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, the present invention will be described in detail based on specific embodiments.

[0023] (1. Optical laminate) As shown in FIG. 1, the optical laminate 1 according to the present embodiment preferably has a first member 31, a first adhesive layer 11, an intermediate layer 20, a second adhesive layer 12, and a second member 32 laminated in this order. Further, in a plane perpendicular to the lamination direction of the optical laminate 1 (in FIG. 1, the surface 31a of the first member or the surface 32a of the second member), the hardness measured by an E-type durometer is preferably 96 or more. By controlling the hardness of the optical laminate 1 within the above range, the generation of marks caused by deformation due to local load can be suppressed.

[0024] In the present embodiment, the above hardness is preferably 96 or more, more preferably 97 or more, and even more preferably 98 or more. On the other hand, the upper limit of the hardness is preferably 100 or less.

[0025] The thickness of the optical laminate according to this embodiment is preferably 5 to 2500 μm, more preferably 7 to 2500 μm, even more preferably 9 to 1800 μm, particularly preferably 11 to 1200 μm, and most preferably 12 to 600 μm or less. This contributes to miniaturization of the device on which the optical laminate is mounted. Furthermore, from the viewpoint of achieving both bendability and good flexibility in combination with the storage modulus ratio and loss tangent ratio described later, the thickness is preferably 20 to 250 μm, more preferably 30 to 200 μm, preferably 40 to 150 μm, particularly preferably 50 to 130 μm, and even more preferably 60 to 125 μm.

[0026] The optical laminate according to this embodiment is preferably bendable. Bendable means that it can be bent once during manufacturing and maintain that bent state without damage in the mounted device, or that repeated bending does not cause damage in the mounted device. The bending angle at the time of bending should be between 0° and 180°.

[0027] In this embodiment, when the optical laminate 1 shown in Figure 1 is bent such that the first member 31 is compressed and the second member 32 is stretched (when bent so that the ends of the first member come into contact with each other), it is preferable to control the physical properties of the adhesive layer as follows.

[0028] (1.1. Storage modulus ratio) In this embodiment, it is preferable to control the ratio of the storage modulus G'1 of the first adhesive layer at 25°C to the storage modulus G'2 of the second adhesive layer at 25°C. Specifically, it is preferable that the ratio of the storage modulus G'1 of the first adhesive layer at 25°C to the storage modulus G'2 of the second adhesive layer at 25°C (G'1 / G'2) is less than 0.133. That is, it is preferable that the storage modulus G'1 of the first adhesive layer is relatively smaller than the storage modulus G'2 of the second adhesive layer. This allows for a balanced relaxation of the compressive stress generated on the first adhesive layer side and the tensile stress generated on the second adhesive layer side. As a result, even when the ends of the first member are bent so that they come into contact with each other, damage or abnormal appearance at the bent portion can be suppressed. Furthermore, it is possible to make it easier to satisfy the hardness requirements mentioned above.

[0029] From the above viewpoint, the storage modulus ratio (G'1 / G'2) is preferably 0.0001 to 0.100, more preferably 0.0005 to 0.70, even more preferably 0.001 to 0.050, particularly preferably 0.002 to 0.030, and among these, preferably 0.003 to 0.020, and most preferably 0.004 to 0.010.

[0030] (1.2.Loss tangent ratio) In this embodiment, it is preferable to control the ratio of the loss tangent tanδ1 of the first adhesive layer at 25°C to the loss tangent tanδ2 of the second adhesive layer at 25°C. Specifically, it is preferable that the ratio of the loss tangent tanδ1 of the first adhesive layer at 25°C to the loss tangent tanδ2 of the second adhesive layer at 25°C (tanδ1 / tanδ2) is greater than 1.1. That is, it is preferable that the loss tangent tanδ1 of the first adhesive layer is relatively larger than the loss tangent tanδ2 of the second adhesive layer. This makes it easier to satisfy the hardness described above, and even if a localized load is applied to the first adhesive layer, that load can be distributed. As a result, the occurrence of marks caused by deformation due to localized loads can be suppressed.

[0031] From the above viewpoint, the loss tangent ratio (tanδ1 / tanδ2) is preferably 1.15 to 10, more preferably 1.2 to 7, even more preferably 1.25 to 4, particularly preferably 1.3 to 3, and most preferably 1.35 to 2.

[0032] (2. First adhesive layer and second adhesive layer) As shown in Figure 1, the first adhesive layer 11 bonds the intermediate layer 20 and the first member 31. When the optical laminate is bent, the first adhesive layer 11 is located on the inside compared to the second adhesive layer 12.

[0033] As shown in Figure 1, the second adhesive layer 12 bonds the intermediate layer 20 and the second member 32. When the optical laminate is bent, the second adhesive layer 12 is located on the outside compared to the first adhesive layer 11.

[0034] The first adhesive layer and the second adhesive layer may consist of one layer (single layer) or two or more layers. If the first adhesive layer has multiple layers, these layers may be identical or different from each other, and there are no particular restrictions on the combination of layers that make up these multiple layers.

[0035] The thickness of the first adhesive layer 11 is preferably 1 to 500 μm, more preferably 3 to 250 μm, and even more preferably 6 to 150 μm. This makes it easier to satisfy the hardness mentioned above. Furthermore, from the viewpoint of achieving a laminate that is both bendable and has good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, the thickness is preferably 9 to 90 μm, particularly preferably 12 to 60 μm, more preferably 15 to 45 μm, and even more preferably 18 to 30 μm.

[0036] The thickness of the second adhesive layer 12 is preferably 1 to 500 μm, more preferably 2 to 250 μm, even more preferably 3 to 100 μm, particularly preferably 4 to 50 μm, and most preferably 5 to 10 μm. This makes it easier to satisfy the hardness mentioned above. Furthermore, in addition to being bendable, this makes it easier to obtain a laminate that also has good flexibility, in combination with the storage modulus ratio and loss tangent ratio mentioned above.

[0037] In order to satisfy the above physical properties, it is preferable that the first adhesive layer, the first adhesive constituting the first adhesive layer, the second adhesive layer, and the second adhesive constituting the second adhesive layer satisfy the following physical properties.

[0038] (2.1. Storage Modulus) In this embodiment, the storage modulus G'1 of the first adhesive at 25°C is preferably 0.001 to 4 MPa. The storage modulus is one of the indicators of the ease of deformation (hardness) of the adhesive layer. This makes it easy to keep the storage modulus ratio and loss tangent ratio within the above range. It also makes it easier to satisfy the hardness mentioned above. From this viewpoint, the storage modulus of the first adhesive is more preferably 0.005 to 2 MPa, and even more preferably 0.008 to 1 MPa. Furthermore, from the viewpoint of achieving bendability and a laminate that also achieves good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, it is more preferably 0.01 to 0.6 MPa, particularly preferably 0.02 to 0.3 MPa, even more preferably 0.03 to 0.1 MPa, and most preferably 0.04 to 0.08 MPa.

[0039] In this embodiment, the storage modulus G'2 of the second adhesive at 25°C is preferably 0.01 to 100 MPa. This makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. It also makes it easier to satisfy the hardness mentioned above. From this viewpoint, the storage modulus of the second adhesive is preferably 0.01 to 100 MPa, preferably 0.1 to 50 MPa, and from the viewpoint of obtaining a laminate that also has flexibility, it is more preferably 0.5 to 20 MPa, particularly preferably 1 to 10 MPa, and even more preferably 3 to 8 MPa.

[0040] (2.2. Loss Modulus) In this embodiment, the loss modulus G"1 of the first adhesive at 25°C is preferably 0.001 to 2 MPa. The loss modulus is one indicator of the ease of deformation (hardness) of the adhesive layer. This makes it easier to keep the storage modulus ratio and the loss tangent ratio within the above range. It also makes it easier to satisfy the hardness mentioned above. From this viewpoint, the loss modulus of the first adhesive is more preferably 0.003 to 1 MPa, and even more preferably 0.006 to 0.6 MPa. Furthermore, from the viewpoint of achieving a laminate that is bendable and also has good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, it is more preferably 0.008 to 0.2 MPa, particularly preferably 0.009 to 0.1 MPa, and even more preferably 0.01 to 0.06 MPa.

[0041] In this embodiment, the loss modulus G"2 of the second adhesive at 25°C is preferably 0.001 to 10 MPa. This makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. It also makes it easier to satisfy the hardness mentioned above. From this viewpoint, the loss modulus of the second adhesive is more preferably 0.005 to 6 MPa, and even more preferably 0.01 to 3 MPa. Furthermore, from the viewpoint of achieving a laminate that is bendable and also has good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, it is more preferably 0.05 to 2 MPa, particularly preferably 0.1 to 1.5 MPa, and even more preferably 0.5 to 1 MPa.

[0042] (2.3. Loss tangent) In this embodiment, the loss tangent tanδ1 of the first adhesive at 25°C is preferably 0.1 to 2. The loss tangent is defined as "loss modulus / storage modulus" and is a value measured by a dynamic viscoelasticity measuring device based on the response to stress applied to the object. This makes it easy to keep the storage modulus ratio and the loss tangent ratio within the above range. From this viewpoint, the loss tangent of the first adhesive is preferably 0.2 to 1.5, and more preferably 0.22 to 1.2. Furthermore, from the viewpoint of achieving bendability and a laminate that also achieves good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, it is more preferably 0.24 to 1, even more preferably 0.25 to 0.7, particularly preferably 0.27 to 0.5 or less, and most preferably 0.28 to 0.4.

[0043] In this embodiment, the loss tangent tanδ2 of the second adhesive at 25°C is preferably 0.01 to 1. This makes it easier to keep the storage modulus ratio and the loss tangent ratio within the above range. From this viewpoint, the loss tangent of the second adhesive is more preferably 0.05 to 0.6, and even more preferably 0.08 to 0.3 or less. Furthermore, from the viewpoint of achieving a laminate that is both bendable and has good flexibility in combination with the storage modulus ratio and loss tangent ratio mentioned above, it is preferably 0.1 to 0.27, particularly preferably 0.15 to 0.25, and even more preferably 0.18 to 0.22.

[0044] Furthermore, the storage modulus, loss modulus, and loss tangent of the first and second adhesives can be adjusted, for example, by changing the composition of the first or second adhesive (type and amount of reactive functional groups, molecular structure of the monomer composition used, glass transition temperature, etc.), the molecular weight of the materials constituting the first or second adhesive, etc.

[0045] The storage modulus and loss modulus of the first and second adhesives can be measured by known methods. For example, the first or second adhesive can be prepared as a sample of a predetermined size, and the elastic modulus can be measured by applying strain to the sample at a predetermined frequency within a predetermined temperature range using a dynamic viscoelasticity measuring device. From the measured elastic modulus, the storage modulus and loss modulus under the above conditions can be calculated. The loss tangent can also be calculated from the storage modulus and loss modulus measured in the above-described method.

[0046] (2.4.Adhesion) In this embodiment, the adhesive strength of the first adhesive layer to the soda-lime glass is preferably 1 to 50 N / 25 mm. This allows for good adhesion between components and makes it easier to satisfy the hardness requirements mentioned above. It also makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. From this viewpoint, the adhesive strength of the first adhesive layer to the soda-lime glass is preferably 3 to 40 N / 25 mm, more preferably 5 to 30 N / 25 mm, and from the viewpoint of achieving a laminate with good flexibility, it is even more preferably 7 to 25 N / 25 mm, particularly preferably 8 to 20 N / 25 mm, and most preferably 8.5 to 15 N / 25 mm.

[0047] In this embodiment, the adhesive strength of the second adhesive layer to the soda-lime glass is preferably 0.2 to 50 N / 25 mm. This allows for good adhesion between the components and makes it easier to satisfy the hardness requirements mentioned above. It also makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. From this viewpoint, the adhesive strength of the second adhesive layer to the soda-lime glass is preferably 0.6 to 30 N / 25 mm, more preferably 1 to 10 N / 25 mm or less, and even more preferably 1.5 to 7 N / 25 mm, and particularly preferably 2 to 3.5 N / 25 mm, from the viewpoint of obtaining a laminate that also has good flexibility.

[0048] (2.5. Gel fraction) In this embodiment, the gel fraction of the first adhesive is preferably 30 to 99%. This makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. Furthermore, it is possible to achieve good adhesion between members, easily satisfy the hardness mentioned above, and easily form a laminate that also has good flexibility. From this viewpoint, the gel fraction of the first adhesive is more preferably 40 to 95%, even more preferably 50 to 90%, particularly preferably 60 to 85%, and most preferably 65 to 80%. The gel fraction of the first adhesive can be measured by the method shown in the test example described later.

[0049] In this embodiment, the gel fraction of the second adhesive is preferably 40 to 100%. This makes it easier to keep the storage modulus ratio and loss tangent ratio within the above range. Furthermore, it is possible to achieve good adhesion between members, easily satisfy the hardness mentioned above, and easily form a laminate that also has good flexibility. From this viewpoint, the gel fraction of the second adhesive is more preferably 60 to 99.9%, even more preferably 80 to 99%, particularly preferably 90 to 85%, and most preferably 95 to 98%. The gel fraction of the second adhesive can be measured by the method shown in the test example described later.

[0050] (2.6. Composition of the first and second adhesives) The composition of the first and second adhesives is not particularly limited, as long as the hardness measured by an E-type durometer is within the above range. The adhesive may be, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, etc. Furthermore, the adhesive may be an emulsion type, a solvent type, or a solvent-free type. In addition, the first and second adhesives may or may not have a cross-linked structure.

[0051] In this embodiment, from the viewpoint of ease of realizing the above-mentioned physical properties, and from the viewpoint of adhesive properties, optical properties, etc., an acrylic adhesive is preferred as the adhesive. Furthermore, the acrylic adhesive may be curable by active energy rays or not curable by active energy rays. Acrylic adhesives having a crosslinked structure are more preferred as the first and second adhesives.

[0052] Specifically, the first adhesive is preferably an adhesive obtained from an adhesive composition mainly composed of (meth)acrylic acid ester polymer (A) (hereinafter sometimes referred to as "adhesive composition P1"), and is particularly preferably an adhesive obtained by crosslinking adhesive composition P1 containing (meth)acrylic acid ester polymer (A) and a crosslinking agent (B). Furthermore, the second adhesive is preferably an adhesive formed from an adhesive composition mainly composed of (meth)acrylic acid ester polymer (A) and a crosslinking agent (B) (hereinafter sometimes referred to as "adhesive composition P2"), and is particularly preferably an adhesive obtained by crosslinking adhesive composition P2 containing (meth)acrylic acid ester polymer (A) and a crosslinking agent (B). Such adhesives are likely to satisfy the above-mentioned physical properties and easily provide good adhesive strength. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Also, the concept of "polymer" is included in the term "polymer".

[0053] The adhesives constituting the first adhesive and the adhesives constituting the second adhesive may be of the same type or of different types. For example, one may be an acrylic adhesive that is curable by active energy rays, and the other may be an acrylic adhesive that is not curable by active energy rays. Furthermore, even if both are acrylic adhesives that are curable by active energy rays or acrylic adhesives that are not curable by active energy rays, the composition of the adhesives and the monomer composition of the main polymer may be different.

[0054] (2.6.1. (meth)acrylic acid ester polymer) The (meth)acrylic acid ester polymer (A) preferably contains an alkyl (meth)acrylic acid ester and a monomer having a reactive functional group in its molecule (a monomer containing a reactive functional group) as monomer units constituting the polymer.

[0055] By including an alkyl (meth)acrylate ester, the resulting adhesive can exhibit desirable tackiness. Preferably, the alkyl (meth)acrylate ester has an alkyl group with 1 to 20 carbon atoms. The alkyl group may be linear, branched, or have a cyclic structure.

[0056] Examples of alkyl (meth)acrylate esters having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate.

[0057] Among these, (meth)acrylic acid esters with 1 to 8 carbon atoms in the alkyl group are preferred from the viewpoint of controlling the storage modulus, loss modulus, and loss tangent. Specifically, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These may be used individually or in combination of two or more.

[0058] The (meth)acrylic acid ester polymer (A) preferably contains 60 to 99.9% by mass, more preferably 70 to 99.5% by mass, even more preferably 80 to 99% by mass, and particularly preferably 85 to 98% by mass, of alkyl (meth)acrylic acid esters having 1 to 20 carbon atoms in the alkyl group as monomer units constituting the polymer. This allows for the imparting of suitable tackiness to the resulting first and second adhesives. In particular, it is possible to achieve good adhesion between components, easily satisfy the aforementioned hardness, and easily obtain laminates that also have good flexibility. Furthermore, other monomer components can be introduced into the (meth)acrylic acid ester polymer (A) in desired amounts, making it easier to design adhesives that exhibit desired performance.

[0059] The (meth)acrylic acid ester polymer (A) contains a monomer containing a reactive functional group as a monomer unit constituting the polymer. Through the reactive functional group derived from the reactive functional group containing the monomer, the (meth)acrylic acid ester polymer (A) reacts with the crosslinking agent (B) described later, forming a crosslinked structure (three-dimensional network structure) in the adhesive. As a result, an adhesive with the desired cohesive force is obtained.

[0060] Preferred monomers containing reactive functional groups include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers). These reactive functional group-containing monomers may be used individually or in combination of two or more.

[0061] Among the monomers containing reactive functional groups, monomers containing hydroxyl groups or monomers containing carboxyl groups are preferred. In particular, it is preferable that the first adhesive uses a monomer containing hydroxyl groups without containing a monomer containing carboxyl groups, and that the second adhesive uses a combination of monomers containing hydroxyl groups and monomers containing carboxyl groups. This makes it easier to satisfy the above-mentioned physical properties related to storage modulus, loss modulus, and loss tangent, and also makes it easier to fine-tune the storage modulus, loss modulus, and loss tangent. Furthermore, it is possible to achieve good adhesion between components, easily satisfy the hardness mentioned above, and easily obtain a laminate that also has good flexibility.

[0062] Examples of hydroxyl group-containing monomers include hydroxyalkyl esters of (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. Among these, hydroxyalkyl esters of (meth)acrylates having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred from the viewpoint of easily achieving the above-mentioned physical properties. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

[0063] 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 or methacrylic acid is preferred, and acrylic acid is particularly preferred, from the viewpoint of easily achieving the aforementioned physical properties related to storage modulus, loss modulus, loss tangent, and adhesive strength. These may be used alone or in combination of two or more.

[0064] The (meth)acrylic acid ester polymer (A) preferably contains 0.1 to 40% by mass of reactive functional group-containing monomers as monomer units constituting the polymer, more preferably 0.5 to 30% by mass, and even more preferably 1 to 20% by mass. Furthermore, the first adhesive more preferably contains 1.2 to 10% by mass of the reactive functional group-containing monomers, more preferably 1.5 to 4% by mass, and more preferably 1.8 to 3% by mass. On the other hand, the second adhesive more preferably contains 2 to 15% by mass of the reactive functional group-containing monomers, more preferably 3 to 12% by mass, and more preferably 4 to 8% by mass. As a result, the cohesive forces of the first and second adhesives obtained by the crosslinking reaction with the crosslinking agent (B) are appropriate, and the physical properties and adhesive strength related to the storage modulus, loss modulus, and loss tangent described above are easily satisfied. Furthermore, it is possible to achieve good adhesion between components, easily satisfy the aforementioned hardness requirements, and easily obtain a laminate that also possesses good flexibility.

[0065] It is also preferable that the (meth)acrylic acid ester polymer (A) does not contain carboxyl group-containing monomers as monomer units constituting the polymer. Since the carboxyl group is an acidic component, by not containing carboxyl group-containing monomers, it is possible to suppress problems caused by acid (corrosion, change in resistance, etc.) even when the object to which the adhesive is applied is a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, or a metal mesh.

[0066] Here, "carboxy group-containing monomer-free" means substantially free of carboxy group-containing monomers, including not only complete absence of carboxy group-containing monomers, but also the possibility of containing carboxy group-containing monomers to an extent that does not cause corrosion of transparent conductive films or metal wiring due to carboxyl groups. Specifically, it means that the (meth)acrylic acid ester polymer (A) may contain carboxy group-containing monomers as monomer units 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.

[0067] In this embodiment, the (meth)acrylic acid ester polymer may optionally contain other monomers as monomer units constituting the polymer. As the other monomers, monomers that do not contain reactive functional groups are preferred in order not to inhibit the effects of the reactive functional group-containing monomers described above. Examples of such monomers include unreactive nitrogen atom-containing monomers such as N-vinyl-2-pyrrolidone, alkoxyalkyl (meth)acrylate esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used individually or in combination of two or more.

[0068] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0069] The weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 100,000 to 3,000,000, and more preferably 200,000 to 2,500,000. In the case of the first adhesive, the weight-average molecular weight is even more preferably 400,000 to 2,000,000, particularly preferably 700,000 to 1,600,000, and most preferably 900,000 to 1,400,000. On the other hand, in the case of the second adhesive, the weight-average molecular weight is more preferably 500,000 to 2,300,000, even more preferably 800,000 to 2,100,000, even more preferably 1,200,000 to 2,000,000, and most preferably 1,600,000 to 1,900,000. As a result, the resulting adhesive is likely to satisfy the above-mentioned physical properties and adhesive strength related to storage modulus, loss modulus, and loss tangent. Furthermore, it is possible to achieve good adhesion between components, easily satisfy the aforementioned hardness, and easily obtain a laminate that also has good flexibility. Note that the weight-average molecular weight in this specification is the value on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0070] In adhesive compositions P1 and P2, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more types.

[0071] (2.6.2. Crosslinking agents) The crosslinking agent (B) crosslinks the (meth)acrylic acid ester polymer (A) upon heating of the adhesive composition P1 or P2 containing the crosslinking agent (B), forming a crosslinked structure (three-dimensional network structure). As a result, the cohesive force of the resulting adhesive is improved, making it easier to satisfy the aforementioned physical properties and adhesive strength related to the storage modulus, loss modulus, and loss tangent.

[0072] The crosslinking agent (B) can be any agent that reacts with the reactive groups of the (meth)acrylic acid ester polymer (A). Examples include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. Among these, it is preferable to use an isocyanate crosslinking agent or an epoxy crosslinking agent that has excellent reactivity with monomers containing reactive functional groups. Note that the crosslinking agent (B) can be used alone or in combination of two or more types.

[0073] Isocyanate-based crosslinking agents include 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 which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.

[0074] Examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxyl groups.

[0075] The content of the crosslinking agent (B) in adhesive composition P1 and adhesive composition P2 is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, even more preferably 0.1 to 1 part by mass, and particularly preferably 0.2 to 0.5 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A). This makes it easier to satisfy the physical properties and adhesive strength related to the storage modulus, loss modulus, and loss tangent mentioned above. Furthermore, it is possible to achieve good adhesion between members, easily satisfy the hardness mentioned above, and easily obtain a laminate that also has good flexibility.

[0076] (2.6.3. Other Additives) Adhesive composition P1 or adhesive composition P2 may optionally contain additives commonly used in acrylic adhesives. Examples of such additives include silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, colorants, infrared absorbers, light stabilizers, softeners, rust inhibitors, fillers, and refractive index modifiers. Polymerization solvents and diluent solvents described later are not included in the additives constituting adhesive composition P1 and adhesive composition P2.

[0077] In this embodiment, it is preferable that the adhesive composition P1 and adhesive composition P2 contain a silane coupling agent (C). This improves the adhesion between the first adhesive layer and the second adhesive layer obtained, resulting in a more desirable adhesive strength and excellent flexibility, as well as making it easier to obtain an optical laminate that easily satisfies the aforementioned hardness requirements.

[0078] The silane coupling agent (C) is preferably an organosilicon compound having at least one alkoxysilyl group in its molecule. Furthermore, the silane coupling agent (C) is preferably one that has good compatibility with the (meth)acrylic acid ester polymer (A) and is light-transmitting.

[0079] Examples of such silane coupling agents (C) include polymerizable unsaturated silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Examples include silicon compounds containing a lucapto group, amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, or condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used individually or in combination of two or more.

[0080] The content of the silane coupling agent (C) in adhesive composition P1 and adhesive composition P2 is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, even more preferably 0.1 to 1 part by mass, and particularly preferably 0.2 to 0.5 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A). As a result, the resulting first adhesive layer and second adhesive layer have improved adhesion to the adherend and greater adhesive strength. Furthermore, it is easier to obtain an optical laminate that easily satisfies the aforementioned hardness requirements.

[0081] In this embodiment, the adhesive composition P1 may also preferably include an energy-ray curable resin (D) and a photopolymerization initiator (E). As a result, the first adhesive obtained will have sufficient curing of the energy-ray curable resin, allowing for the acquisition of a highly elastic adhesive layer and an optical laminate that easily satisfies the hardness properties described above.

[0082] In this embodiment, the adhesive composition P2 preferably contains an energy-ray curable resin (D) and a photopolymerization initiator (E). This allows the second adhesive to cure sufficiently with respect to the energy-ray curable resin. As a result, the second adhesive is more likely to have a higher modulus of elasticity than the first adhesive, making it easier to keep the storage modulus ratio within the above range.

[0083] As the energy-ray curable resin (D), monomers or oligomers having unsaturated groups in the molecule and capable of polymerization curing by energy-ray irradiation are preferred.

[0084] Examples of energy-ray curable resins (D) include polyvalent (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate, as well as oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate. These may be used individually or in combination of two or more types.

[0085] The content of the energy-curable resin (D) in adhesive composition P1 is preferably 1 to 50 parts by mass, more preferably 8 to 40 parts by mass, and even more preferably 16 to 30 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A). On the other hand, the content of the energy-curable resin (D) in adhesive composition P2 is preferably 1 to 50 parts by mass, more preferably 4 to 38 parts by mass, even more preferably 8 to 28 parts by mass, and most preferably 12 to 18 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A).

[0086] Examples of photopolymerization initiators (E) include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and other photoinitiators, as well as photosensitizers such as amines and quinones. Specifically, examples include α-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, benzyl dimethyl ketal, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0087] The content of the photopolymerization initiator (E) in adhesive composition P1 and adhesive composition P2 is preferably 1 to 30 parts by mass, more preferably 4 to 20 parts by mass, and even more preferably 8 to 15 parts by mass, per 100 parts by mass of energy ray curable resin.

[0088] (3. Manufacturing of adhesive compositions) The adhesive composition P1 for preparing the first adhesive and the adhesive composition P2 for preparing the second adhesive can be produced, for example, by first producing a (meth)acrylic acid ester polymer (A), and then mixing the obtained (meth)acrylic acid ester polymer (A) with a crosslinking agent (B). Additives may be added as needed.

[0089] (Meth)acrylic acid ester polymer (A) can be produced, for example, by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. Polymerization of (meth)acrylic acid ester polymer (A) can be carried out by solution polymerization using a polymerization initiator as needed. Polymerizing (meth)acrylic acid ester polymer (A) using solution polymerization makes it easier to increase the molecular weight of the resulting polymer, adjust the molecular weight distribution, and further reduce the generation of low molecular weight products.

[0090] Examples of polymerization solvents used in solution polymerization include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone. One type of polymerization solvent may be used, or two or more types may be used in combination.

[0091] Examples of polymerization initiators include azo compounds and organic peroxides, and two or more may be used in combination. Furthermore, the weight-average molecular weight of the resulting polymer can be adjusted by incorporating a chain transfer agent such as 2-mercaptoethanol during the polymerization process.

[0092] Next, the crosslinking agent (B) and diluent are added to the solution of the obtained (meth)acrylic acid polymer (A) and thoroughly mixed to obtain adhesive composition P1 and adhesive composition P2 (coating solution) diluted with the solvent. Additives may be added as needed.

[0093] Furthermore, if any of the above components is a solid component, or if it precipitates when mixed with other components in an undiluted state, that component may be dissolved or diluted in a diluting solvent beforehand before being mixed with the other components.

[0094] Examples of diluent solvents include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride 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 solvents such as ethyl cellosolve.

[0095] The concentration and viscosity of the prepared coating solution can be selected as appropriate depending on the situation, as long as they are within the range of coating. For example, adhesive composition P1 and adhesive composition P2 are diluted to a concentration of 10 to 60% by mass, respectively. Note that the addition of diluent solvents is not a necessary condition when obtaining the coating solution; if adhesive composition P1 and adhesive composition P2 have a viscosity suitable for coating, diluent solvents may not be added. In this case, adhesive composition P1 and adhesive composition P2 become coating solutions in which the polymerization solvent of (meth)acrylic acid ester polymer (A) is used directly as the diluent.

[0096] (4. Manufacturing of adhesives) The adhesives (first adhesive and second adhesive) constituting the adhesive layers (first adhesive layer and second adhesive layer) are preferably obtained by crosslinking the adhesive composition P1 and adhesive composition P2 described above. Crosslinking of adhesive composition P1 and adhesive composition P2 can usually be carried out by heat treatment. This heat treatment can also be combined with the drying treatment used to volatilize diluent solvents, etc., from the coating films of adhesive composition P1 and adhesive composition P2 applied to the desired object.

[0097] The heating temperature for the heat treatment is preferably 50 to 150°C, and more preferably 70 to 120°C, for adhesive composition P1 and adhesive composition P2. The heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes, for adhesive composition P1 and adhesive composition P2.

[0098] After heat treatment, a curing period of 1 to 2 weeks at room temperature (e.g., 23°C, 50% RH) may be provided as needed. If curing is necessary, an adhesive with a cross-linked structure (first adhesive and second adhesive) will be obtained after the curing period. If curing is not necessary, an adhesive with a cross-linked structure (first adhesive and second adhesive) will be obtained after the heat treatment is completed.

[0099] In this embodiment, the first adhesive is preferably in the form of an adhesive sheet sandwiched between two release sheets. Specifically, a coating solution of adhesive composition P1 is applied to the release surface of one release sheet manufactured by a known method, and the adhesive composition P1 is crosslinked by heat treatment to form a coating layer. Subsequently, the coating layer and the release surface of the other release sheet are bonded together. If curing is required, after a predetermined curing period, the coating layer becomes the first adhesive layer. If curing is not required, the coating layer remains the first adhesive layer. The second adhesive is also preferably in the form of an adhesive sheet sandwiched between two release sheets, similar to the first adhesive.

[0100] Methods for applying the coating solutions of adhesive compositions P1 and P2 include bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0101] (5. Middle class) As shown in Figure 1, the intermediate layer 20 is sandwiched between the first adhesive layer 11 and the second adhesive layer 12. That is, one main surface of the intermediate layer 20 is attached to the first adhesive layer 11, and the other main surface is attached to the second adhesive layer 12. Furthermore, the intermediate layer 20 is attached to other members (first member 31 and second member 32) via the first adhesive layer 11 and the second adhesive layer 12.

[0102] Therefore, the optical laminate 1 integrates three components (intermediate layer 20, first component 31, and second component 32) via a first adhesive layer and a second adhesive layer.

[0103] The Young's modulus of the intermediate layer is preferably 0.01 to 100 GPa, more preferably 0.05 to 50 GPa, even more preferably 0.08 to 10 GPa, and particularly preferably 0.1 to 2 GPa. This, combined with the properties of the other components, makes it easier to achieve the aforementioned hardness and flexibility.

[0104] The thickness of the intermediate layer can be appropriately set according to the intended use, as long as the desired optical properties are obtained and bending does not cause damage or abnormal appearance. In this embodiment, from the viewpoint of making it easier to achieve the hardness and flexibility mentioned above in combination with the properties of the other components, the thickness of the intermediate layer is preferably 1 to 500 μm, more preferably 3 to 250 μm, even more preferably 6 to 150 μm, and particularly preferably 9 to 90 μm. From the viewpoint of thinning the optical laminate and optical performance, it is more preferably 12 to 60 μm, even more preferably 15 to 45 μm, and most preferably 18 to 30 μm.

[0105] (5.1. Material of the intermediate layer) The material of the intermediate layer can be appropriately selected according to the intended use, as long as the desired optical properties are obtained and no damage or cosmetic abnormalities occur when bending occurs. In this embodiment, a resin material can be suitably selected.

[0106] Examples of intermediate layer resin materials include films or laminated films made of polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, poly-methylpentene-1, and polybutene-1; polyurethane resins; polycarbonate resins; polyvinyl chloride resins; polyethersulfone resins; polyethylene sulfide resins; styrene resins; acrylic resins; polyamide resins; polyimide resins; and cellulose resins such as cellulose acetate. Among these, polyester resins, polyolefin resins, polycarbonate resins, acrylic resins, polyamide resins, polyimide resins, and cellulose resins are preferred, with polyester resins being more preferred from the viewpoint of handling and optical properties.

[0107] In this embodiment, it is also preferable to select a glass material in addition to a resin material. Glass materials are suitable as components included in an optical laminate because they have excellent optical properties and high hardness and transparency, but they are highly susceptible to breakage when bent. However, even when a glass material is used as an intermediate layer, in combination with the properties of the first adhesive layer and the second adhesive layer described above in this embodiment, it is possible to improve the physical properties related to the hardness of the optical laminate while reducing the risk of breakage. Therefore, when a glass material is included in the intermediate layer, the thickness of the glass material is preferably 1 to 2000 μm, more preferably 10 to 1500 μm, even more preferably 25 to 1000 μm, particularly preferably 40 to 500 μm, and most preferably 50 to 200 μm, from the viewpoint of thinning the optical laminate.

[0108] Examples of intermediate layers having the above materials include cover films, barrier films, hard coat films, polarizing films (polarizing plates), polarizers, phase difference films (phase difference plates), viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transparent reflective films, electrode films, transparent conductive films, metal mesh films, film sensors (touch sensor films), liquid crystal polymer films, light-emitting polymer films, film-type liquid crystal modules, organic EL modules (organic EL films, organic EL elements), electronic paper modules (film-type electronic paper), and TFT (Thin Film Transistor) substrates.

[0109] (6. First component) As shown in Figure 1, the first member 31 is attached to the first adhesive layer 11 and is attached to other members (intermediate layer 20 and second member 32) via the first adhesive layer 11 and the second adhesive layer 12. When the optical laminate 1 is bent, the first member 31 is located on the inside compared to the second member 32. Therefore, compressive stress acts on the bent portion of the first member 31.

[0110] The Young's modulus of the first member is preferably 0.01 to 100 GPa, and more preferably 0.05 to 50 GPa or less. If the first member does not have a hard coat layer, it is even more preferably 0.08 to 5 GPa, and particularly preferably 0.1 to 1 GPa. If the first member has a hard coat layer, it is even more preferably 0.1 to 20 GPa, and particularly preferably 1 to 10 GPa. This, combined with the properties of the members other than the first member, makes it easier to achieve the aforementioned hardness and flexibility.

[0111] The thickness of the first member can be appropriately set according to the intended use, as long as the desired optical properties are obtained and bending does not cause damage or abnormal appearance. In this embodiment, from the viewpoint of making it easier to achieve the hardness and flexibility mentioned above in combination with the properties of members other than the first member, the thickness of the first member is preferably 1 to 500 μm, more preferably 5 to 250 μm, even more preferably 10 to 180 μm, and from the viewpoint of thinning the optical laminate and optical performance, it is preferably 15 to 120 μm, particularly preferably 20 to 90 μm, and most preferably 30 to 60 μm.

[0112] (6.1. Material of the first component) The material of the first component can be appropriately selected according to the intended use, as long as the desired optical properties are obtained and no damage or cosmetic abnormalities occur when bent. In this embodiment, a resin material can be suitably selected.

[0113] Examples of the resin material for the first component include films made of the same resin materials as those listed above as the resin material for the intermediate layer, or laminated films thereof. Among these, polyester resins, polyolefin resins, acrylic resins, polyamide resins, and polyimide resins are preferred, and cellulose resins are more preferred from the viewpoint of ease of handling, optical properties, and ease of achieving the hardness mentioned above.

[0114] When an optical laminate is used in a device such as a display, examples of first components having the above-mentioned material include cover films, barrier films, hard coat films, polarizing films (polarizing plates), polarizers, phase difference films (phase difference plates), viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transparent reflective films, electrode films, transparent conductive films, metal mesh films, film sensors (touch sensor films), liquid crystal polymer films, light-emitting polymer films, film-type liquid crystal modules, organic EL modules (organic EL films, organic EL elements), electronic paper modules (film-type electronic paper), TFT (Thin Film Transistor) substrates, and the like.

[0115] (6.2.Functional layer) In this embodiment, a functional layer may be formed on the surface of the first member. Examples of functions of the functional layer include hard coating properties, anti-glare properties, fingerprint resistance, slipperiness, antistatic properties, improved writing feel, anti-Newton ring properties, high transparency, and antistatic properties. The functional layer may have multiple of these functions. Furthermore, these functions may differ depending on whether the functional layer is provided on the side of the first adhesive layer of the first member or on the opposite side (exposed to the outside). From the viewpoint of protecting the member placed directly beneath the functional layer, it is preferable that the functional layer be provided on the side of the first member opposite to the first adhesive layer. In particular, from the viewpoint of achieving the hardness described above, it is preferable that the functional layer be a hard coating layer, and it may also be a hard coating layer that has functions other than hard coating properties. Therefore, it is preferable that the hard coating layer be made of a material that is superior to the first member in terms of hardness, scratch resistance, weather resistance, etc.

[0116] When the functional layer is a hard coat layer, the thickness of the hard coat layer is preferably 1 to 50 μm, more preferably 2 to 25 μm, even more preferably 3 to 15 μm, and particularly preferably 4 to 8 μm. This improves the surface hardness and scratch resistance of the first component, and the resulting optical laminate is more likely to satisfy the hardness properties described above.

[0117] The constituent material of the hard coat layer is preferably a cured product of a hard coat layer forming composition containing a curable component such as an energy-ray curable resin or a thermosetting resin. From the viewpoint of easily achieving the hardness described above, it is preferable that the cured product is formed from a hard coat layer forming composition containing an energy-ray curable resin. The hard coat layer forming composition optionally contains a leveling agent, a filler, a photopolymerization initiator, etc. A polyfunctional (meth)acrylate is preferably used as the energy-ray curable resin.

[0118] (7. Second component) As shown in Figure 1, the second member 32 is attached to the second adhesive layer 12 and is attached to other members (intermediate layer 20 and first member 31) via the first adhesive layer 11 and the second adhesive layer 12. When the optical laminate 1 is bent, the second member 32 is located on the outside compared to the first member 31. Therefore, tensile stress acts on the bent portion of the second member 32.

[0119] The Young's modulus of the second member is preferably 0.01 to 100 GPa, more preferably 0.05 to 50 GPa, even more preferably 0.1 to 10 GPa, and particularly preferably 0.2 to 2 GPa. This, combined with the properties of the other members, makes it easier to achieve the aforementioned hardness and flexibility.

[0120] The thickness of the second member can be appropriately set according to the intended use, as long as the desired optical properties are obtained and bending does not cause damage or abnormal appearance. In this embodiment, from the viewpoint of making it easier to achieve the hardness and flexibility mentioned above in combination with the properties of the members other than the second member, the thickness of the second member is preferably 1 to 500 μm, more preferably 5 to 250 μm, even more preferably 10 to 150 μm, and from the viewpoint of thinning the optical laminate and optical performance, it is preferably 15 to 100 μm, particularly preferably 20 to 80 μm, and most preferably 25 to 60 μm.

[0121] (7.1. Material of the second component) The material of the second component can be appropriately selected according to the intended use, as long as the desired optical properties are obtained and no damage or cosmetic abnormalities occur when bent. In this embodiment, a resin material can be suitably selected.

[0122] Examples of the resin material for the second component include films made of the same resin materials as those listed above as the resin material for the intermediate layer, or laminated films thereof. Among these, polyester resins, polyolefin resins, acrylic resins, polyamide resins, and polyimide resins are preferred, and from the viewpoint of ease of handling, optical properties, and ease of achieving the hardness mentioned above, polyamide resins and polyimide resins are more preferred, with polyimide resins being particularly preferred.

[0123] When an optical laminate is used in a device such as a display, examples of second components having the above-mentioned material include cover films, barrier films, hard coat films, polarizing films (polarizing plates), polarizers, phase difference films (phase difference plates), viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transparent reflective films, electrode films, transparent conductive films, metal mesh films, film sensors (touch sensor films), liquid crystal polymer films, light-emitting polymer films, film-type liquid crystal modules, organic EL modules (organic EL films, organic EL elements), electronic paper modules (film-type electronic paper), and TFT (ThinFilmTransistor) substrates.

[0124] (8. Manufacturing of optical laminates) An example of manufacturing an optical laminate is shown. First, one release sheet is peeled off from an adhesive sheet having a first adhesive layer, and the exposed first adhesive layer is bonded to one side of the intermediate layer. Then, one release sheet is peeled off from an adhesive sheet having a second adhesive layer, and the exposed second adhesive layer is bonded to the other side of the intermediate layer.

[0125] Next, the other release sheet is peeled off from the first adhesive layer, and the exposed first adhesive layer is bonded to the first member. Then, the other release sheet is peeled off from the second adhesive layer, and the exposed second adhesive layer is bonded to the second member to form an optical laminate. Note that the bonding order of each member (intermediate layer, first member, and second member) may be changed.

[0126] (9. Devices) The device according to this embodiment comprises the optical laminate described above, and is preferably a display such as a display. Examples of such devices include organic electroluminescent (OLED) displays, electrophoretic displays (electronic paper), liquid crystal displays using a plastic substrate (film) as the substrate, light-emitting diode (LED) displays, foldable displays, and the like. The device may also include a touch panel.

[0127] Furthermore, the device may consist solely of optical laminates, or it may be composed of one or more optical laminates and other components. Because the hardness of the surface of the first component in the optical laminate is controlled within the above range, even if a localized load is applied to the first component, the load is distributed across the first component and the components located below it, thereby suppressing the formation and retention of marks on the surface of the first component.

[0128] Furthermore, if the device is a bendable device, since the components are bonded together by the first and second adhesive layers described above, damage and abnormal appearance at the bent portion can be suppressed even when repeatedly bent (for example, 100,000 times).

[0129] Figure 2 shows an example of a device according to this embodiment: a foldable device. However, the device according to the present invention is not limited to this device.

[0130] As shown in Figure 2, the bendable device 5 is constructed by laminating, from top to bottom, a cover film 51, an adhesive layer 52, a polarizing film 53, an adhesive layer 54, a touch sensor film 55, an adhesive layer 56, an organic EL element 57, an adhesive layer 58, and a TFT substrate 59. The cover film 51, polarizing film 53, touch sensor film 55, organic EL element 57, and TFT substrate 59 are bendable components. The adhesive layer 52 is the first adhesive layer described above, and the adhesive layer 58 is the second adhesive layer described above.

[0131] In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y."

[0132] Although embodiments of the present invention have been described above, the present invention is not limited in any way to the embodiments described above, and may be modified in various ways within the scope of the present invention. [Examples]

[0133] The invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0134] 1. Preparation of adhesive compositions A to D (Meth)acrylic acid ester polymer (A) was prepared by copolymerizing 49 parts by mass of 2-ethylhexyl acrylate, 49 parts by mass of n-butyl acrylate, and 2 parts by mass of 4-hydroxybutyl acrylate. The molecular weight of the obtained (meth)acrylic acid ester polymer (A) was measured by the method shown below, and the weight-average molecular weight (Mw) was 1 million.

[0135] The weight-average molecular weight (Mw) is the weight-average molecular weight on a polystyrene basis, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). (Measurement conditions) • GPC measuring device: Tosoh Corporation, HLC-8020 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Guard Column HXL-H TSK gel GMHXL (x2) TSK gel G2000HXL • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0136] 100 parts by mass (based on solid content; the same applies hereinafter) of the (meth)acrylic acid ester polymer (A) obtained above, 0.2 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), and 0.3 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of adhesive composition A.

[0137] The composition and weight-average molecular weight (Mw) of the (meth)acrylic acid ester polymer (A), the amount of crosslinking agent (B), and the amounts of other components (energy-ray curable resin (D) and photopolymerization initiator (E)) were changed to the formulations shown in Table 1 to obtain adhesive compositions B to D.

[0138] 2. Manufacturing of adhesive sheets for characteristic measurement The coating solution of the obtained adhesive composition was applied using a knife coater to the peeled surface of a release sheet 1, which was obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent. The coated layer was then heated at 90°C for 1 minute to promote a crosslinking reaction, forming a coating layer consisting of an adhesive having a crosslinked structure composed of a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B).

[0139] Next, the coating layer on the release sheet 1 obtained above was bonded to the release sheet 2, which had one side of a polyethylene terephthalate film peeled off with a silicone-based release agent, so that the peeled-off surface of the release sheet 2 was in contact with the coating layer. By curing under conditions of 23°C and 50% relative humidity for 7 days, an adhesive sheet having an adhesive layer with a thickness of 25 μm was produced. Release sheet 1 had a greater peeling force than release sheet 2.

[0140] For adhesive compositions B to D, the coating layer was cured by irradiation with ultraviolet light after formation. The ultraviolet irradiation conditions were as follows: <Ultraviolet irradiation conditions> • Use of high-pressure mercury lamps ·Illuminance 200mW / cm 2 , light intensity 1000mJ / cm 2 • The UV irradiance / light intensity meter used is the "UVPF-A1" manufactured by iGraphics Co., Ltd.

[0141] This adhesive sheet had the following configuration: release sheet 1 / adhesive layer (thickness: 25 μm) / release sheet 2. The thickness of the adhesive layer was measured in accordance with JIS K7130 using a constant-pressure thickness gauge (TECLOCK PG-02).

[0142] (Example 1) 1. Manufacturing of the first adhesive layer The coating solution of the adhesive composition A obtained above was applied using a knife coater to the release-treated surface of a release sheet 3, which had one side of a polyethylene terephthalate film released with a silicone-based release agent, so that the thickness after drying would be 25 μm. The coating layer was then heated at 90°C for 1 minute to promote a crosslinking reaction, forming a coating layer consisting of an adhesive having a crosslinked structure composed of a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B).

[0143] Next, the coating layer on the release sheet 3 obtained above was bonded to the release sheet 4, which had one side of a polyethylene terephthalate film peeled off with a silicone-based release agent, so that the peeled-off surface of the release sheet 4 was in contact with the coating layer. By curing the bonded bond for 7 days under conditions of 23°C and 50% relative humidity, an adhesive sheet having a first adhesive layer with a thickness of 25 μm was produced. This adhesive sheet had the following configuration: release sheet 3 / first adhesive layer (thickness: 25 μm) / release sheet 4. The thickness of the first adhesive layer was measured in accordance with JIS K7130 using a constant-pressure thickness gauge (Teclock PG-02). Furthermore, release sheet 3 had a greater peeling force than release sheet 4.

[0144] 2. Manufacturing of the second adhesive layer The coating solution of the adhesive composition C obtained above was applied using a knife coater to the peeled surface of a release sheet 5, which had one side of a polyethylene terephthalate film peeled with a silicone-based release agent, so that the thickness after drying would be 5 μm. The coated layer was then heated at 90°C for 1 minute to promote a crosslinking reaction, forming a coating layer consisting of an adhesive having a crosslinked structure composed of a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B).

[0145] Next, the coating layer on the release sheet 5 obtained above was bonded to the release sheet 6 (UV-insensitive), which had one side of the polyethylene terephthalate film peeled off with a silicone-based release agent, so that the peeled-off surface of the release sheet 6 was in contact with the coating layer. After that, the coating layer was cured by irradiating it with ultraviolet light through the release sheet 6. The ultraviolet irradiation conditions were as follows. <Ultraviolet irradiation conditions> • Use of high-pressure mercury lamps ·Illuminance 200mW / cm 2 , light intensity 1000mJ / cm 2 • The UV irradiance / light intensity meter used is the "UVPF-A1" manufactured by iGraphics Co., Ltd.

[0146] Then, by curing the material for 7 days under conditions of 23°C and 50% relative humidity, an adhesive sheet with a second adhesive layer of 5 μm thickness was produced. This adhesive sheet had the following configuration: release sheet 5 / second adhesive layer (thickness: 5 μm) / release sheet 6. The thickness of the second adhesive layer was measured in accordance with JIS K7130 using a constant-pressure thickness gauge (TECLOCK PG-02). Furthermore, release sheet 5 had a greater peeling force than release sheet 6.

[0147] 3. Manufacturing of optical laminates The release sheet 4 was peeled off from the adhesive sheet having the first adhesive layer, and one main surface of polyethylene terephthalate (PET) (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100", thickness: 25 μm) as an intermediate layer was attached to the exposed surface of the first adhesive layer. Subsequently, the release sheet 6 was peeled off from the adhesive sheet having the second adhesive layer, and the other main surface of the polyethylene terephthalate was attached to the exposed surface of the second adhesive layer, thereby forming a laminate having the configuration of release sheet 3 / first adhesive layer / intermediate layer / second adhesive layer / release sheet 5.

[0148] Next, the release sheet 3 on the first adhesive layer side was peeled off from the obtained laminate, and one main surface of triacetylcellulose (TAC) (manufactured by Konica Minolta, product name "Konica Minolta Tack KC4UAW", thickness: 40 μm), which is the first component, was attached to the exposed surface of the first adhesive layer. Subsequently, the release sheet 5 on the second adhesive layer side was peeled off from the obtained laminate, and one main surface of polyimide (PI) film (manufactured by Mitsubishi Gas Chemical Company, product name "NeoPrim(r) L-3450", thickness: 50 μm), which is the second component, was attached to the exposed surface of the second adhesive layer, thereby forming an optical laminate having the configuration of first component / first adhesive layer / intermediate layer / second adhesive layer / second component.

[0149] (Examples 2-5, Comparative Examples 1 and 2) An optical laminate was manufactured in the same manner as in Example 1, except that the adhesive compositions constituting the first adhesive layer and the adhesive compositions constituting the second adhesive layer were in the combinations shown in Table 2, and the thicknesses of the first and second adhesive layers were as shown in Table 2.

[0150] In Examples 3 and 5, a hard coat (HC) layer with a thickness of 5 μm was formed on the surface of the first member. The hard coat layer was formed by mixing 100 parts by mass of polyfunctional (meth)acrylate (manufactured by Shin Nakamura Chemical Industry, product name "NK Ester A-DPH") (this value is calculated on a solid content basis; the same applies to other components below), 4.3 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator, 11 parts by mass of silica microparticles (manufactured by Fuji Silysia Chemical Co., Ltd., product name "Silohobic 702", average particle size 4.1 μm), 0.01 parts by mass of a leveling agent (manufactured by Toray Dow Corning, product name "SH28"), and 8.3 parts by mass of silica nanoparticles (manufactured by Nissan Chemical Industries, Ltd., product name "MIBK-ST", average particle size: 10 nm), diluting the mixture with propylene glycol monomethyl ether to prepare a hard coat layer forming composition. The coating solution of this composition was applied to the surface of the first member, the diluting solvent was removed by heating, and then the hard coat layer forming composition was cured by irradiation with ultraviolet light. Furthermore, ultraviolet irradiation was performed under a nitrogen atmosphere using a high-pressure mercury lamp at an illuminance of 200 mW / cm². 2 , light intensity 300mJ / cm 2 The procedure was performed under the following ultraviolet irradiation conditions.

[0151] [Table 1]

[0152] Details of the abbreviations and other terms listed in Table 1 are as follows: ((meth)acrylic acid ester polymer (A)) 2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate 4HBA: 4-hydroxybutyl acrylate AAc: Acrylic acid (Crosslinking agent (B)) B1: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") (Silane coupling agent (C)) C1:3-Glycidoxypropyltrimethoxysilane (Activated energy ray curable resin (D)) D1: ε-Caprolactone-modified tris-(2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300-1CL") (Photopolymerization initiator (E)) E1: 2,4,6-trimethylbenzoyl diphenyl phosphine oxide

[0153] (Storage modulus, loss modulus, and loss tangent of the adhesive layer) Multiple layers of the adhesive sheet prepared above were laminated to form a 3mm thick laminate. From the resulting laminate of adhesive layers, a cylindrical body with a diameter of 8mm (height 3mm) was punched out to be used as a sample for measuring the storage modulus, loss modulus, and loss tangent.

[0154] For the samples used for measurement, the storage modulus, loss modulus, and loss tangent were measured using the torsional shear method with a viscoelasticity analyzer (Anton-Paar, MCR302) in accordance with JIS K7244-6, under the conditions of a measurement temperature of 25°C, a measurement frequency of 1 Hz, and a heating rate of 4°C / min. The results are shown in Table 1.

[0155] For the optical laminates obtained in the examples and comparative examples, the ratio (G'1 / G'2) of the storage modulus G'1 of the first adhesive constituting the first adhesive layer at 25°C to the storage modulus G'2 of the second adhesive constituting the second adhesive layer at 25°C was calculated. In addition, the ratio (tanδ1 / tanδ2) of the loss tangent tanδ1 of the first adhesive constituting the first adhesive layer at 25°C to the loss tangent tanδ2 of the second adhesive constituting the second adhesive layer at 25°C was calculated. The results are shown in Table 2.

[0156] (Measurement of adhesive strength of the adhesive layer) The release sheet 4 was peeled off from the adhesive sheet having the first adhesive layer (adhesive composition A: thickness 25 μm) obtained in Example 1. The exposed first adhesive layer was laminated to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4160", thickness: 100 μm) having an easy-adhesion layer, to obtain a laminate of release sheet 3 / adhesive layer / PET film. The obtained laminate was cut into strips 25 mm wide and 100 mm long, and these were used as samples.

[0157] Under conditions of 23°C and 50% relative humidity, the release sheet 3 was peeled off the above sample, and the exposed adhesive layer 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 in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. After that, it was left for 24 hours under conditions of 23°C and 50% relative humidity, and the adhesive strength (N / 25mm) was measured using a tensile testing machine (manufactured by Orientec Co., Ltd., product name "Tensilon") under conditions of peeling speed of 300 mm / min and peeling angle of 180 degrees. Measurements under conditions other than those described herein were performed in accordance with JIS Z 0237:2009. The results are shown in Table 1.

[0158] Similarly, the adhesive strength was measured for the second adhesive layer obtained in Example 1 (adhesive composition C: thickness 5 μm), the second adhesive layer obtained in Example 2 (adhesive composition D: thickness 5 μm), the second adhesive layer obtained in Example 4 (adhesive composition D: thickness 15 μm), and the second adhesive layer obtained in Comparative Example 1 (adhesive composition B: thickness 5 μm). The results are shown in Table 1.

[0159] (Evaluation of the gel fraction of the adhesive) The adhesive layers, each composed of adhesive compositions A to D prepared in the examples, were cut to a size of 80 mm x 80 mm. These adhesive layers were then wrapped in a polyester mesh (product name: Tetron Mesh #200), and their mass was weighed using a precision balance. The mass of the adhesive alone was calculated by subtracting the mass of the mesh alone from the weighed value. This mass was designated as M1.

[0160] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. The mesh was then removed and air-dried for 24 hours at 23°C and 50% relative humidity, followed by 12 hours of drying in an oven at 80°C. After drying, its mass was weighed using a precision balance. The mass of the adhesive alone was calculated by subtracting the mass of the mesh alone from the weighed value. This mass was designated M2. Using the obtained M1 and M2, the gel fraction was calculated using the following formula. The results are shown in Table 1. Gel fraction (%) = (M2 / M1) × 100

[0161] Next, the characteristics of the optical laminate were evaluated as follows.

[0162] (hardness) Eight optical laminates prepared in the examples and comparative examples were stacked to create a sample for measurement. The surface hardness of the first component of the obtained sample was measured using an E-type durometer (Muratec KDS Co., Ltd., product name "Rubber Hardness Tester DM-207E") under conditions of 23°C and 50% relative humidity. The results are shown in Table 2.

[0163] (Evaluation of indentation) The surfaces of the second members of the optical laminates prepared in the examples and comparative examples were attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) using an adhesive (Lintec Corporation, product name "NCF D692(5)").

[0164] Next, the surface of the first component of the optical laminate was pressed with the tip of a stylus pen (Apple Pencil, manufactured by Apple Inc.) with a load of 500g for 10 seconds. The pressed area was visually observed 1 minute, 5 minutes, and 15 minutes after the stylus pen press was stopped, and evaluated according to the following criteria. The results are shown in Table 2. ◎: No indentations left ○: An indentation is visible after 1 minute, but not after 5 minutes or 15 minutes. △: Indentations are visible after 1 minute and 5 minutes, but not after 15 minutes. ×: Indentations were still visible after 15 minutes.

[0165] (flexibility) The optical laminates prepared in the examples and comparative examples were cut into 50 mm wide and 200 mm long pieces, and these were used as samples. The obtained samples were repeatedly bent using a durability tester (Yuasa System Equipment Co., Ltd., product name "Surface Condition No-Load U-Shape Expansion Tester Model: DLDMLH-FS") under the following conditions. After the test, the interface between the first adhesive layer and the intermediate layer, and between the second adhesive layer and the intermediate layer in the bent portion was visually inspected for any abnormalities such as lifting or peeling, and the repeated bending performance was evaluated according to the following criteria. The results are shown in Table 2. <Test Conditions> Bending direction: The first member bends so that it faces the opposite side. Minimum bending diameter: φ3mm and φ2mm Number of flexions: 200,000 Bending speed: 60rpm <Evaluation Criteria for Repeated Flexibility> A... No abnormalities in the appearance of the bent part. B... Although there are no visible abnormalities in the bent area, a crease remains. C... Abnormal appearance at the bend. <Comprehensive evaluation criteria for repeated bending resistance> ◎...No abnormalities were found in the appearance of the bent portion in tests with a minimum bending diameter of φ3mm and φ2mm. ○...In the test with a minimum bending diameter of φ3mm, there were no abnormalities in the appearance of the bent part, but in the test with a minimum bending diameter of φ2mm, although there were no abnormalities in the appearance of the bent part, a crease remained. △...In the test with a minimum bending diameter of φ3mm, there were no abnormalities in the appearance of the bent part, but in the test with a minimum bending diameter of φ2mm, a crease remained in the bent part. ×...Abnormal appearance of the bent portion was observed in tests with minimum bending diameters of φ3mm and φ2mm.

[0166] [Table 2]

[0167] Table 2 confirms that the occurrence of indentations is suppressed in optical laminates with hardness within the above range. [Industrial applicability]

[0168] The optical laminate of the present invention can be suitably used in devices such as displays. [Explanation of symbols]

[0169] 1...Optical laminate 11...First adhesive layer 12…Second adhesive layer 20…Middle class 31...First component 32...Second component 5. Flexible devices 51…Cover film 52…Adhesive layer 53…Polarizing film 54…Adhesive layer 55... Touch sensor film 56…Adhesive layer 57…Organic EL elements 58…Adhesive layer 59…TFT substrate

Claims

1. An optical laminate in which a first member, a first adhesive layer, an intermediate layer, a second adhesive layer, and a second member are laminated in this order, An optical laminate in which the hardness of the surface of the first member, as measured by an E-type durometer, is 96 or higher.

2. The optical laminate according to claim 1, wherein the optical laminate is bendable in a direction in which compressive stress is generated in the first member.

3. Storage modulus G' of the second adhesive constituting the second adhesive layer at 25°C 2 Storage modulus G' of the first adhesive constituting the first adhesive layer at 25°C. 1 The ratio (G' 1 / G' 2 The optical laminate according to claim 1 or 2, wherein the coefficient of

4. The loss tangent tanδ of the second adhesive constituting the second adhesive layer at 25°C 2 The loss tangent tanδ of the first adhesive constituting the first adhesive layer at 25°C relative to the first adhesive layer. 1 The ratio (tanδ 1 / tanδ 2 The optical laminate according to claim 1 or 2, wherein the coefficient of

5. The optical laminate according to claim 1 or 2, wherein the thickness of the optical laminate is 5 μm or more and 2500 μm or less.

6. The optical laminate according to claim 1 or 2, wherein the thickness of the first adhesive layer is 1 μm or more and 500 μm or less.

7. The optical laminate according to claim 1 or 2, wherein the thickness of the second adhesive layer is 1 μm or more and 500 μm or less.

8. A device comprising the optical laminate according to claim 1 or 2.

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