WO2023276655A1

WO2023276655A1 - Optical layered body

Info

Publication number: WO2023276655A1
Application number: PCT/JP2022/023780
Authority: WO
Inventors: 美菜子野田; 大生三浦; 翔寳田
Original assignee: 日東電工株式会社
Priority date: 2021-06-30
Filing date: 2022-06-14
Publication date: 2023-01-05
Also published as: CN117642288A; KR20240028348A; TW202311027A; JP2023006652A

Abstract

This optical layered body (X) includes: an optical film (10); a pressure-sensitive adhesive layer (20, 30); a substrate (40); and a release film (50). The optical film (10) has a thickness of 100 μｍ or less. The optical layered body (X) includes a lateral-surface uneven edge section (E). In the lateral-surface uneven edge section (E), the end edge (32) of the pressure-sensitive adhesive layer (30) is retracted more than the end edges of the optical film (10) and the release film (50), in a surface direction (D) orthogonal to the thickness direction (T) of the optical film (10).

Description

optical laminate

The present invention relates to an optical laminate.

A display panel has a laminated structure including, for example, a pixel panel, a touch panel, and a surface protective film. An optical film having a predetermined optical function is provided in the laminated structure of the display panel. Examples of optical films include film-like polarizing plates and retardation films. In the process of manufacturing a display panel, for example, an optical laminate in which an optical film is provided on a pixel panel is produced as an intermediate product. The optical laminate includes a pixel panel, an adhesive layer, an optical film, an adhesive layer, and a release film in order in the thickness direction. Further, in the manufacturing process of the display panel, for example, an optical laminate having a surface protective film, an adhesive layer, an optical film, an adhesive layer, and a release film in order in the thickness direction is produced as an intermediate product. be done. Such an optical layered body is described, for example, in Patent Document 1 below.

JP 2020-190754 A

FIG. 8 is a schematic cross-sectional view of an optical layered body Z as an example of a conventional optical layered body. The optical laminate Z includes a substrate 91, an adhesive layer 92, an optical film 93, an adhesive layer 94, and a release film 95 in the thickness direction T in this order. The substrate 91 is, for example, a pixel panel. One surface of the optical film 93 in the thickness direction T is bonded to the substrate 91 via the adhesive layer 92 . The adhesive layer 94 is adhered to the other surface of the optical film 93 . The release film 95 is attached to the adhesive layer 94 in a detachable manner. At the edge E′ of the optical layered body Z, the edge 91e of the substrate 91, the edge 92e of the adhesive layer 92, the edge 93e of the optical film 93, the edge 94e of the adhesive layer 94, and the peeling The edge 95e of the film 95 is flush with each other.

When such an optical laminate Z is used in the manufacturing process of a display panel, the peeling film 95 is peeled off from the adhesive layer 94 (peeling step). In this step, first, at the end E′ of the optical layered body Z, a force for peeling up the release film 95 from the adhesive layer 94 is applied to the release film 95 as a load for starting peeling. This load includes the force required to sufficiently deform the release film 95 at the end E′ and the force required to separate the release film 95 from the adhesive layer 94 elastically deforming following the deformation of the release film 95. are included together. At the end E′, the end of the release film 95 is deformed so as to be separated from the edge 94 e of the pressure-sensitive adhesive layer 94 by applying such a load. Subsequently, the end of the release film 95 is pulled away from the edge 94 e so that the separation between the release film 95 and the adhesive layer 94 progresses, and the release film 95 is separated from the adhesive layer 94 . removed. After that, an adherend (not shown) such as a surface protection film and the optical film 93 are bonded through the exposed adhesive layer 94 .

On the other hand, the development of display panels that can be repeatedly folded (foldable) for smartphones and tablet terminals, for example, is progressing. Foldable display panels require that each element in the laminate structure be thin and flexible.

However, in the conventional optical laminate Z, the thinner the optical film 93 is, the more likely the load for starting peeling in the peeling process described above causes significant deformation of the end portion of the optical film 93 . Deformation of the edge of the optical film 93 causes cracks at the edge, which is not preferable.

The present invention provides an optical laminate suitable for peeling a release film from a thin optical film with an adhesive layer while suppressing edge cracks in the optical film.

The present invention [1] is an optical laminate comprising a substrate, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a release film in this order in the thickness direction, The optical film has a thickness of 100 μm or less, and the edge of the second pressure-sensitive adhesive layer is closer than the edges of the optical film and the release film in the plane direction perpendicular to the thickness direction of the optical film. includes an optical stack having a ridged side edge with a retracted .

As described above, at the uneven side edge of the optical laminate of the present invention, the edge of the second pressure-sensitive adhesive layer is retreated from the edges of the optical film and the release film in the surface direction of the optical film. there is At such a side uneven end portion, the release film has a free portion to which the second pressure-sensitive adhesive layer is not adhered. Therefore, when peeling the release film from the second adhesive layer, the free part of the release film is first turned up and deformed, and then the end of the release film that has already been turned up and deformed. can be pulled to separate the release film from the edge of the second adhesive layer. That is, in the peeling initiation process, the force (first force) for sufficiently deforming the end of the release film, and the peeling film from the edge of the second adhesive layer that elastically deforms following the deformation of the release film (In contrast, the above-described optical layered body Z requires the first force and the second force at the same time. the force required for the initiation process is large). Such an optical laminate is suitable for reducing the force required for the peel initiation process. The smaller this force is, the less the deformation of the edge of the thin optical film with a thickness of 100 μm or less is in the starting process of peeling of the release film, and the less the generation of cracks at the edge of the film. Thus, the optical laminate of the present invention is suitable for peeling a release film from a thin optical film with an adhesive layer while suppressing edge cracks in the optical film.

The present invention [2] is the above-mentioned [1], wherein, at the side uneven end portion, the retraction length of the edge of the second pressure-sensitive adhesive layer from the edge of the release film is 20 μm or more in the surface direction. The optical laminate described in .

In such a configuration, in the process of starting peeling of the release film, before the release film is separated from the edge of the second pressure-sensitive adhesive layer, the end of the release film (the free portion) is sufficiently turned up and deformed. and therefore to reduce the force required to initiate peeling of the release film.

The present invention [3] is the above [ 1] or includes the optical layered body according to [2].

With such a configuration, when the second force for separating the release film from the edge of the second pressure-sensitive adhesive layer acts on the optical layered body in the process of starting peeling of the release film, the first pressure-sensitive adhesive layer is preferable for suppressing the deformation of the first pressure-sensitive adhesive layer, and therefore it is preferable for suppressing separation of the edge of the first pressure-sensitive adhesive layer from the optical film and the substrate.

The present invention [4] is characterized in that, in the side uneven end portion, the distance from the edge of the optical film is less than the retraction length of the edge of the first pressure-sensitive adhesive layer from the edge of the optical film in the plane direction. The optical layered product according to [3] above, in which the edge of the second pressure-sensitive adhesive layer has a small withdrawal length.

The present invention [5] is the above [1] to [4], wherein the distance between the edge of the first adhesive layer and the edge of the second adhesive layer in the surface direction is 1 μm or more. The optical laminated body as described in any one is included.

Such a configuration is preferable for suppressing the above-described deformation of the first pressure-sensitive adhesive layer in the process of starting peeling of the release film. preferred to suppress.

In the present invention [6], the ratio of the retracted length of the edge of the second pressure-sensitive adhesive layer from the edge of the release film to the thickness of the second pressure-sensitive adhesive layer is 0.4 or more and 8 or less. The optical laminate according to any one of [1] to [5] above is included.

In such a configuration, in the process of starting peeling of the release film, before the release film is separated from the edge of the second pressure-sensitive adhesive layer, the end of the release film (the free portion) is sufficiently turned up and deformed. Therefore, it is preferable to reduce the force (total force) required to initiate peeling of the release film.

The present invention [7] is any one of [1] to [6] above, wherein the peel initiation force for starting the peeling of the release film from the second pressure-sensitive adhesive layer is 800 gf / 25 mm or less. The described optical laminate is included.

Such a configuration is preferable for reducing the load on the optical film in the process of starting to peel the release film from the second pressure-sensitive adhesive layer.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of one Embodiment of the optical laminated body of this invention. FIG. 2 is a partially enlarged cross-sectional schematic diagram of an example of an uneven side surface end portion of the optical layered body shown in FIG. 1 ; In this example, the retraction length (d2) of the edge of the second adhesive layer is shorter than the retraction length (d1) of the edge of the first adhesive layer. 2 is a partially enlarged schematic cross-sectional view of another example of the uneven side surface end portion of the optical layered body shown in FIG. 1. FIG. In this example, the retraction length (d2) of the edge of the second adhesive layer is longer than the retraction length (d1) of the edge of the first adhesive layer. 2 is a partially enlarged schematic cross-sectional view of another example of the uneven side surface end portion of the optical layered body shown in FIG. 1. FIG. In this example, the edge of the first pressure-sensitive adhesive layer is not retracted in the plane direction from the edge of the optical film. An example of how to use the optical layered body of the present invention is shown. FIG. 5A shows a peeling step of peeling the peeling film, and FIG. 5B shows a bonding step of bonding the optical film and the adherend via the second pressure-sensitive adhesive layer. FIG. 4 is a schematic diagram for explaining the blade angle of the rotary blades used in the contouring process in Examples and Comparative Examples. An example of the graph obtained by the peeling test which peels the peeling film on an adhesive layer from an adhesive layer is represented. It is a cross-sectional schematic diagram of the conventional optical laminated body.

As shown in FIG. 1, an optical laminate X as an embodiment of the optical laminate of the present invention includes an optical film 10, an adhesive layer 20 (first adhesive layer), and an adhesive layer 30 (second adhesive layer), a substrate 40, and a release film 50. The optical layered body X has a sheet shape with a predetermined thickness and spreads in a direction perpendicular to the thickness direction T (surface direction D). Specifically, the optical laminate X includes a substrate 40, an adhesive layer 20, an optical film 10, an adhesive layer 30, and a release film 50 in the thickness direction T in this order.

The optical film 10 is a functional optical film. Functional optical films include, for example, film-like polarizing plates (polarizing films) and retardation films. The optical film 10 is a film incorporated in the laminated structure of the foldable display panel in this embodiment. A foldable display panel has a laminated structure including, for example, a pixel panel and a touch panel. The optical film 10 has a first surface 11 as one surface in the thickness direction and a second surface 12 opposite to the first surface 11 . The optical film 10 has a thickness of 100 μm or less. The adhesive layer 20 is adhered to the first surface 11 . The base material 40 is bonded to the first surface 11 via the adhesive layer 20 . Substrates 40 include pixel panels and plastic films for foldable displays. The adhesive layer 30 adheres to the second surface 12 and has an adhesive surface 31 on the side opposite to the optical film 10 . The peel film 50 is arranged on the adhesive surface 31 so as to be peelable. The release film 50 has flexibility. In the optical layered body X, the optical film 10 has an edge 13, the adhesive layer 20 has an edge 22, and the adhesive layer 30 has an edge 32 as edges that define the outline shape in plan view. , the substrate 40 has an edge 42 and the release film 50 has an edge 52 . Such an optical layered body X is a layered body incorporated in the layered structure of the foldable display panel.

The optical layered body X has an uneven side edge E on all or part of the outer peripheral edge of the film. At the uneven side edge E, the edge 32 of the pressure-sensitive adhesive layer 30 is retreated from the

edges

13 and 52 of the optical film 10 and the release film 50 in the surface direction D. 2 to 4 are partially enlarged cross-sectional schematic diagrams of examples of the side uneven end portion E of the optical layered body X, respectively. 2 and 3, the edge 22 of the pressure-sensitive adhesive layer 20 retreats in the plane direction D from the edge 13 of the optical film 10. As shown in FIGS. 4, the edge 22 of the pressure-sensitive adhesive layer 20 and the edge 13 of the optical film 10 are flush with each other.

At such an uneven side edge E, the release film 50 has a free portion 50a to which the adhesive layer 30 is not attached. Therefore, in the uneven side edge portion E, when peeling the release film 50 from the adhesive layer 30, first, the free portion 50a of the release film 50 is turned up and deformed, and then the already deformed release film is turned up. The release film 50 can be separated from the edge 32 of the adhesive layer 30 by pulling the free portion 50a of 50 . That is, in the process of starting peeling of the release film 50, the force (first force) for sufficiently deforming the end of the release film 50 and the pressure-sensitive adhesive layer 30 that elastically deforms following the deformation of the release film 50. A force (second force) for pulling the release film 50 away from the edge 32 is not required at the same time. Such an optical layered body X is suitable for reducing the force required for the peeling start process of the peeling film 50 . The smaller this force is, the more the deformation of the thin optical film 10 with a thickness of 100 μm or less is suppressed in the process of starting the peeling of the release film 50 , and the crack generation at the edge of the film is suppressed.

As described above, the optical laminate X is suitable for peeling the release film 50 from the thin optical film 10 with an adhesive layer while suppressing edge cracks in the optical film 10 .

The retraction length of the edge 32 of the adhesive layer 30 from the edge 52 of the release film 50 in the surface direction D is preferably 20 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more. In such a configuration, the free portion 50a of the release film 50 is fully turned up and deformed before the release film 50 is separated from the edge 32 of the adhesive layer 30 in the process of starting the release of the release film 50 described above. Therefore, it is preferable to reduce the force (total force) required to start the peeling of the peeling film 50 . The retraction length is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less. As a method for adjusting the retraction length, for example, adjustment of cutting conditions in a cutting step, which will be described later, which is performed using a rotary blade to form the side uneven end portion E, can be mentioned. The cutting conditions include, for example, the taper angle of the cutting edge of the rotary blade, the number of rotations of the rotary blade, the incident direction of the rotary blade with respect to the surface of the optical film laminate described later, and the displacement of the rotary blade for cutting the optical film laminate. speed. Methods for adjusting the retraction length include, for example, adjusting the thickness and modulus of the adhesive layer 30 .

The ratio of the retraction length to the thickness of the adhesive layer 30 is preferably 0.5 or more, more preferably 0.8 or more, and even more preferably 1 or more. The ratio is preferably 8 or less, more preferably 6 or less. These configurations are preferable for sufficiently turning up and deforming the free portion 50a of the release film 50 before the release film 50 is separated from the edge 32 of the adhesive layer 30 in the process of starting the release of the release film 50. Therefore, it is preferable to reduce the force required to start the peeling of the peeling film 50 .

2 and 3, the edge 22 of the pressure-sensitive adhesive layer 20 retreats in the plane direction D from the edge 13 of the optical film 10 and the edge 42 of the substrate 40. preferably With such a configuration, when the second force for separating the release film 50 from the edge 32 of the adhesive layer 30 acts on the optical layered body X in the process of starting peeling of the release film 50, the pressure-sensitive adhesive It is preferable for suppressing deformation of the layer 20 , and therefore preferable for suppressing separation of the edge 22 of the pressure-sensitive adhesive layer 20 from the optical film 10 and the substrate 40 .

The retraction length (retraction length d1) of the edge 22 of the adhesive layer 20 from the edge 13 of the optical film 10 in the plane direction D is preferably 20 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more. is. Such a configuration is preferable for suppressing deformation of the pressure-sensitive adhesive layer 20 when the second force is applied to the optical layered body X. It is preferable to suppress leaving from. The retraction length d1 is preferably 500 μm or less, more preferably 400 μm or less, still more preferably 300 μm or less. As a method for adjusting the retraction length d1, for example, adjustment of cutting conditions in a cutting step performed using a rotary blade to form the side uneven end portion E, which will be described later, is exemplified. The cutting conditions include, for example, the taper angle of the cutting edge of the rotary blade, the number of rotations of the rotary blade, the incident direction of the rotary blade with respect to the surface of the optical film laminate described later, and the displacement of the rotary blade for cutting the optical film laminate. speed. Methods for adjusting the retraction length d1 include, for example, adjustment of the thickness of the pressure-sensitive adhesive layer 20 and adjustment of the elastic modulus.

At the uneven side edge E, the retraction length d2 of the edge 32 of the adhesive layer 30 from the edge 13 of the optical film 10 is preferably smaller than the retraction length d1 as shown in FIG. That is, retraction length d1 is preferably greater than retraction length d2. Also, the ratio (d1/d2) of the retraction length d1 to the retraction length d2 is preferably 1.1 or more, more preferably 1.2 or more. These configurations are preferable for suppressing the above-described deformation of the adhesive layer 20 in the process of starting peeling of the release film 50, so that the edge 22 of the adhesive layer 20 is separated from the optical film 10 and the substrate 40. preferred to suppress. The ratio (d1/d2) is, for example, 5 or less.

The distance between the

edges

22, 32 in the plane direction D (that is, the difference between the retraction length d1 and the retraction length d2) is preferably 1 µm or more, more preferably 5 µm or more, and even more preferably 10 µm or more. Such a configuration is preferable for suppressing the above-described deformation of the adhesive layer 20 in the above-described separation initiation process of the release film 50. It is preferable to suppress leaving from. Also, the distance between the

edges

22 and 32 in the surface direction D is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 220 μm or less. Such a configuration is preferable for suppressing damage to the edges of the optical film 10, and also increases the durability of the edges of the optical film 10 due to a decrease in the adhesion area between the optical film 10 and the pressure-sensitive adhesive layers 20 and 30. It is preferable for suppressing a decrease in sexuality.

The peel initiation force F1 for starting peeling of the release film 50 from the adhesive surface 31 of the adhesive layer 30 is preferably 800 gf/25 mm or less, more preferably 700 gf/25 mm or less, and still more preferably 600 gf/25 mm or less. . Such a configuration is preferable for suppressing separation of the edge 32 of the adhesive layer 30 from the optical film 10 and reducing the load on the optical film 10 in the process of starting peeling of the peeling film 50 . Also, the peel initiation force F1 is preferably 10 gf/25 mm or more, more preferably 20 gf/25 mm or more, and even more preferably 30 gf/25 mm or more. Such a configuration is preferable for suppressing lifting (partial peeling) of the release film 50 from the adhesive layer 30 during transportation and handling of the optical layered body X, for example.

In the present embodiment, the peel initiation force is the force required in the peel initiation process when peeling the release film releasably attached to the adhesive layer from the adhesive layer. In the peel initiation process, a force is applied to the release film so that the release film deforms in a direction away from the pressure-sensitive adhesive layer. As a result, the edge of the pressure-sensitive adhesive layer attached to the release film and its vicinity are once elastically deformed so as to follow the deformation of the release film. Then, when the release film is pulled with such a large force that the release film is pulled away from the elastically deformed end of the pressure-sensitive adhesive layer, the separation occurs between the edge of the pressure-sensitive adhesive layer and the vicinity thereof and the release film. occurs and peeling starts. That is, the peel initiation force is the force required to separate the release film from the elastically deformed end of the pressure-sensitive adhesive layer and start peeling of the release film from the pressure-sensitive adhesive layer in the peel initiation process. Such a peel initiation force can be measured by the method described below with respect to the examples below. Methods for adjusting the peel initiation force include, for example, adjusting the thickness of the release film and selecting the type of release treatment agent on the pressure-sensitive adhesive layer side surface of the release film.

The peeling force F2 for peeling the peeling film 50 from the adhesive surface 31 of the adhesive layer 30 after the peeling of the peeling film 50 from the adhesive layer 30 is started is preferably 0.1 gf/25 mm or more, more preferably 0.1 gf/25 mm or more. It is 3 gf/25 mm or more, more preferably 0.5 gf/25 mm or more. The peel force F2 is preferably 5 gf/25 mm or less, more preferably 4 gf/25 mm or less, still more preferably 3 gf/25 mm or less.

When the optical film 10 is a film-shaped polarizing plate (polarizing film), examples of the polarizing film include a polarizing film comprising a polarizer and a transparent protective film attached to one or both sides of the polarizer. . Polarizers include, for example, uniaxially stretched hydrophilic polymer films to which a dichroic substance is adsorbed, and oriented polyene films. Hydrophilic polymer films include, for example, polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films. Dichroic substances include, for example, iodine and dichroic dyes. Examples of oriented polyene films include dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.

A thin polarizer with a thickness of 10 μm or less may be used as the polarizer. Examples of thin polarizers include polarizers described in JP-A-51-069644, JP-A-2000-338329, WO2010/100917, Japanese Patent No. 4691205, and Japanese Patent No. 4751481. .

As the transparent protective film for the polarizing plate, a film that is excellent in transparency, mechanical strength, thermal stability, water barrier properties, and optical isotropy is preferred. Materials for such transparent protective films include, for example, cellulose resins, cyclic polyolefin resins, acrylic resins, phenylmaleimide resins, and polycarbonate resins.

From the viewpoint of flexibility, the thickness of the polarizing plate is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less.

The adhesive layer 20 is a pressure-sensitive adhesive layer formed from the first adhesive composition. The adhesive layer 20 has transparency (visible light transmittance). The first PSA composition contains at least a base polymer.

The base polymer is an adhesive component that makes the adhesive layer 20 exhibit adhesiveness. Base polymers include, for example, acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. The base polymer may be used alone or in combination of two or more. From the viewpoint of ensuring good transparency and adhesiveness in the pressure-sensitive adhesive layer 20, an acrylic polymer is preferably used as the base polymer.

The acrylic polymer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester. "(Meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms is preferably used. The (meth)acrylic acid alkyl ester may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.

Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylate Heptyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) ) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (that is, lauryl acrylate), isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, (meth) Pentadecyl acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and tricyclic (Meth)acrylic acid esters having the above aliphatic hydrocarbon ring can be mentioned. Cycloalkyl (meth)acrylates include, for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. (Meth)acrylic esters having a tricyclic or higher aliphatic hydrocarbon ring include, for example, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate , 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

As the (meth)acrylic acid alkyl ester, an acrylate alkyl ester having an alkyl group having 3 to 15 carbon atoms is preferably used, and more preferably n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. At least one selected from the group consisting of dodecyl is used.

The ratio of the (meth)acrylic acid alkyl ester in the monomer component is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably from the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer 20. is 70% by mass or more. The same ratio is, for example, 99% by mass or less.

The monomer component may contain a copolymerizable monomer that can be copolymerized with the (meth)acrylic acid alkyl ester. Examples of copolymerizable monomers include monomers having a polar group. Polar group-containing monomers include, for example, nitrogen atom-containing ring-containing monomers, hydroxy group-containing monomers, and carboxy group-containing monomers. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing cross-linking points into the acrylic polymer and securing the cohesive strength of the acrylic polymer.

Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N -vinylthiazole, and N-vinylisothiazole. N-vinyl-2-pyrrolidone is preferably used as the monomer having a nitrogen atom-containing ring.

The ratio of the monomer having a nitrogen atom-containing ring in the monomer component is preferably 0.1 mass from the viewpoint of ensuring the cohesive force in the adhesive layer 20 and ensuring the adhesive strength of the adhesive layer 20 to the adherend. % or more, more preferably 0.3 mass % or more, and still more preferably 0.55 mass % or more. The same ratio is preferably 30% by mass from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the adhesive layer 20). Below, more preferably 20% by mass or less.

Examples of hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, ( 4-hydroxybutyl meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxy group-containing monomer, 4-hydroxybutyl (meth)acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.

The ratio of the hydroxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the pressure-sensitive adhesive layer 20. It is at least 0.8% by mass, more preferably at least 0.8% by mass. The same ratio is preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the pressure-sensitive adhesive layer 20). .

Carboxy group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The ratio of the carboxyl group-containing monomer in the monomer component is preferable from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer 20, and ensuring adhesion to the adherend in the adhesive layer 20. is 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 0.8% by mass or more. The same ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of acid corrosion of the adherend.

In order to prevent metal elements such as electrodes in a foldable display panel from being corroded by acid components, the adhesive layer 20 preferably has a small acid content. Moreover, when the adhesive layer 20 is used for bonding polarizing plates, the acid content of the adhesive layer 20 is preferably low in order to suppress polyene formation of the polyvinyl alcohol polarizer due to the acid component. The content of organic acid monomers (for example, (meth)acrylic acid and carboxyl group-containing monomers) in such an acid-free pressure-sensitive adhesive layer 20 is preferably 100 ppm or less, more preferably 70 ppm or less, and still more preferably 50 ppm or less. be. The organic acid monomer content of the adhesive layer 20 is obtained by quantifying the acid monomer extracted into water by immersing the adhesive layer 20 in pure water and heating at 100° C. for 45 minutes by ion chromatography. is required by

From the standpoint of acid-free, it is preferable that the base polymer in the pressure-sensitive adhesive layer 20 does not substantially contain an organic acid monomer as a monomer component. From the viewpoint of acid-free, the ratio of the organic acid monomer in the monomer component is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.05% by mass. is 0% by mass.

The monomer component may contain other copolymerizable monomers. Other copolymerizable monomers include, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. be done. These other copolymerizable monomers may be used alone, or two or more of them may be used in combination.

The base polymer has a crosslinked structure in this embodiment. As a method for introducing a crosslinked structure into the base polymer, the base polymer having a functional group capable of reacting with the crosslinker and the crosslinker are blended in the first adhesive composition, and the base polymer and the crosslinker are added to the adhesive layer 20. A base in which a polyfunctional monomer is included in the monomer components forming the base polymer and a branched structure (crosslinked structure) is introduced into the polymer chain by polymerization of the monomer components. A method of forming a polymer (second method) is included. These methods may be used in combination.

Examples of the cross-linking agent used in the first method include compounds that react with functional groups (hydroxy groups, carboxy groups, etc.) contained in the base polymer. Such crosslinkers include, for example, isocyanate crosslinkers, peroxide crosslinkers, epoxy crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, carbodiimide crosslinkers, and metal chelate crosslinkers. The cross-linking agents may be used alone, or two or more of them may be used in combination. As the cross-linking agent, an isocyanate cross-linking agent, a peroxide cross-linking agent, and an epoxy cross-linking agent are preferably used because they are highly reactive with the hydroxy groups and carboxy groups in the base polymer and facilitate the introduction of a cross-linked structure. be done.

Examples of isocyanate cross-linking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, isocyanates, and polymethylene polyphenyl isocyanates. The isocyanate cross-linking agent also includes derivatives of these isocyanates. Examples of the isocyanate derivative include isocyanurate-modified products and polyol-modified products. Commercially available isocyanate cross-linking agents include, for example, Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), Coronate HX (hexa isocyanurate of methylene diisocyanate, manufactured by Tosoh), and Takenate D110N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals).

Peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t- butyl peroxyneodecanoate, t-hexyl peroxypivalate, and t-butyl peroxypivalate.

Examples of epoxy cross-linking agents include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether. , diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

An isocyanate cross-linking agent (especially a bifunctional isocyanate cross-linking agent) and a peroxide cross-linking agent are preferable from the viewpoint of ensuring appropriate flexibility (thus flexibility) of the pressure-sensitive adhesive layer 20 . An isocyanate cross-linking agent (especially a trifunctional isocyanate cross-linking agent) is preferable from the viewpoint of ensuring the durability of the pressure-sensitive adhesive layer 20 . In the base polymer, difunctional isocyanate and peroxide crosslinkers form softer two-dimensional crosslinks, while trifunctional isocyanate crosslinkers form stronger three-dimensional crosslinks. From the viewpoint of achieving both durability and flexibility of the pressure-sensitive adhesive layer 20, it is preferable to use a trifunctional isocyanate cross-linking agent together with a peroxide cross-linking agent and/or a bifunctional isocyanate cross-linking agent.

From the viewpoint of ensuring the cohesive strength of the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and more preferably 100 parts by mass of the base polymer. is 0.07 parts by mass or more. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent blended with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less. is.

In the second method, the monomer components (including the polyfunctional monomer for introducing the crosslinked structure and other monomers) may be polymerized at once or in multiple stages. In the multi-stage polymerization method, first, a monofunctional monomer for forming the base polymer is polymerized (prepolymerization), thereby containing a partially polymerized product (a mixture of a polymerized product with a low degree of polymerization and an unreacted monomer). A prepolymer composition is prepared. Next, after adding a polyfunctional monomer to the prepolymer composition, the partial polymer and the polyfunctional monomer are polymerized (main polymerization).

Examples of polyfunctional monomers include polyfunctional (meth)acrylates containing two or more ethylenically unsaturated double bonds in one molecule. As the polyfunctional monomer, a polyfunctional acrylate is preferable from the viewpoint that a crosslinked structure can be introduced by active energy ray polymerization (photopolymerization).

Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional or higher polyfunctional (meth)acrylates.

Examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol di (meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, Examples include di(meth)acryloyl isocyanurate and alkylene oxide-modified bisphenol di(meth)acrylate.

Examples of trifunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate.

Tetrafunctional or higher polyfunctional (meth)acrylates include, for example, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol pentaacrylate. , and dipentaerythritol hexa(meth)acrylate.

The molecular weight of the polyfunctional monomer is preferably 1500 or less, more preferably 1000 or less. Also, the functional group equivalent (g/eq) of the polyfunctional monomer is preferably 50 or more, more preferably 70 or more, and even more preferably 80 or more. The functional group equivalent weight is preferably 500 or less, more preferably 300 or less, still more preferably 200 or less. These configurations are preferable from the viewpoint of appropriately adjusting viscoelasticity (for example, storage elastic modulus G' and loss tangent tan ?) by introducing a crosslinked structure in the base polymer.

The acrylic polymer can be formed by polymerizing the above monomer components. Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization. Solution polymerization and UV polymerization are preferred from the viewpoints of transparency, water resistance, and cost of the pressure-sensitive adhesive layer 20 . Ethyl acetate and toluene, for example, are used as solvents for solution polymerization. Moreover, as a polymerization initiator, for example, a thermal polymerization initiator and a photopolymerization initiator are used. The amount of the polymerization initiator to be used is, for example, 0.05 parts by mass or more and, for example, 1 part by mass or less with respect to 100 parts by mass of the monomer component.

Thermal polymerization initiators include, for example, azo polymerization initiators and peroxide polymerization initiators. Examples of azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2- imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride mentioned. Peroxide polymerization initiators include, for example, dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxide.

Examples of photopolymerization initiators include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, and benzoin photopolymerization initiators. Initiators include benzyl photoinitiators, benzophenone photoinitiators, ketal photoinitiators, thioxanthone photoinitiators, and acylphosphine oxide photoinitiators.

In polymerization, a chain transfer agent and/or a polymerization inhibitor (polymerization retarder) may be used for the purpose of molecular weight adjustment. Chain transfer agents include α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and α-methylstyrene. Dimers are included.

The molecular weight of the base polymer can be adjusted by adjusting the type and/or amount of the polymerization initiator. For example, in radical polymerization, the larger the amount of the polymerization initiator, the higher the radical concentration in the reaction system, the higher the density of reaction initiation points, and the smaller the molecular weight of the base polymer formed. On the other hand, the smaller the amount of the polymerization initiator, the lower the density of the reaction initiation points, the easier it is for the polymer chain to extend, and the greater the molecular weight of the base polymer formed.

The weight-average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more, from the viewpoint of securing the cohesive force in the pressure-sensitive adhesive layer 20 . The weight-average molecular weight is preferably 5 million or less, more preferably 3 million or less, still more preferably 2 million or less. The weight average molecular weight of the acrylic polymer is calculated by measuring by gel permeation chromatography (GPC) and converting to polystyrene.

The glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. The glass transition temperature is, for example, −80° C. or higher.

For the glass transition temperature (Tg) of the base polymer, the glass transition temperature (theoretical value) obtained based on the following Fox formula can be used. The Fox equation is a relational expression between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of a homopolymer of monomers constituting the polymer. In the Fox formula below, Tg represents the glass transition temperature (° C.) of the polymer, Wi represents the weight fraction of the monomer i constituting the polymer, and Tgi represents the glass transition of the homopolymer formed from the monomer i. Indicates temperature (°C). Literature values can be used for the glass transition temperature of homopolymers. For example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Bunko 7 Introduction to Synthetic Resins for Paints" (Kyozo Kitaoka, Kobunshi Publications, 1995) , which lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of a homopolymer of a monomer can also be determined by the method specifically described in JP-A-2007-51271.

Fox's formula 1/(273+Tg)=Σ[Wi/(273+Tgi)]

The first adhesive composition may contain one or more oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, preferably an acrylic oligomer is used as the oligomer. The acrylic oligomer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.

The glass transition temperature of the acrylic oligomer is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 110°C or higher. The glass transition temperature of the acrylic oligomer is, for example, 200° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower. The combined use of a low-Tg acrylic polymer (base polymer) introduced with a cross-linked structure and a high-Tg acrylic oligomer can increase the adhesive strength of the pressure-sensitive adhesive layer 20, especially at high temperatures. The glass transition temperature of the acrylic oligomer is calculated by the above Fox formula.

The acrylic oligomer having a glass transition temperature of 60° C. or higher is preferably a (meth)acrylic acid alkyl ester having a chain alkyl group (chain alkyl (meth)acrylate) and a (meth)acrylic acid having an alicyclic alkyl group. It is a polymer of a monomer component containing an acid alkyl ester (alicyclic alkyl (meth)acrylate). Specific examples of these (meth)acrylic acid alkyl esters include, for example, the (meth)acrylic acid alkyl esters described above as the monomer component of the acrylic polymer.

As the chain alkyl (meth)acrylate, methyl methacrylate is preferable because it has a high glass transition temperature and excellent compatibility with the base polymer. Preferred alicyclic alkyl (meth)acrylates are dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate. That is, the acrylic oligomer is a monomer component containing methyl methacrylate and at least one selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate. A coalescence is preferred.

The proportion of the alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more. The same ratio is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less. The proportion of chain alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less. The ratio is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more.

The weight average molecular weight of the acrylic oligomer is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. The molecular weight is preferably 30,000 or less, more preferably 10,000 or less, still more preferably 8,000 or less. Such a molecular weight range of the acrylic oligomer is preferable for ensuring the adhesive strength and adhesive holding power of the pressure-sensitive adhesive layer 20 .

The acrylic oligomer is obtained by polymerizing the monomer component of the acrylic oligomer. Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization. In the polymerization of the acrylic oligomer, a polymerization initiator may be used, and a chain transfer agent may be used for the purpose of adjusting the molecular weight.

The content of the acrylic oligomer in the pressure-sensitive adhesive layer 20 is preferably 0.5 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the base polymer, in order to sufficiently increase the adhesive strength of the pressure-sensitive adhesive layer 20 . It is 8 parts by mass or more, more preferably 1 part by mass or more. On the other hand, from the viewpoint of ensuring the transparency of the adhesive layer 20, the content of the acrylic oligomer in the adhesive layer 20 is preferably 5 parts by mass or less, more preferably 4 parts by mass with respect to 100 parts by mass of the base polymer. 3 parts by mass or less, more preferably 3 parts by mass or less. In the pressure-sensitive adhesive layer 20, when the content of the acrylic oligomer is too large, the haze tends to increase and the transparency tends to decrease due to the decrease in compatibility of the acrylic oligomer.

The first adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the first pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

The first adhesive composition may contain other components as necessary. Other ingredients include, for example, tackifiers, plasticizers, softeners, antidegradants, fillers, colorants, UV absorbers, antioxidants, surfactants, and antistatic agents.

The thickness of the adhesive layer 20 is preferably 10 μm or more, more preferably 15 μm or more, from the viewpoint of ensuring sufficient adhesion to the adherend. The thickness of the pressure-sensitive adhesive layer 20 is preferably 300 μm or less, more preferably 200 μm or less, still more preferably 100 μm or less, and particularly preferably 50 μm or less, from the viewpoint of handling.

The haze of the adhesive layer 20 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less. The haze of the pressure-sensitive adhesive layer 20 can be measured using a haze meter according to JIS K7136 (2000). Examples of the haze meter include "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd. and "HM-150 type" manufactured by Murakami Color Research Laboratory.

The total light transmittance of the adhesive layer 20 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher. The total light transmittance of the adhesive layer 20 is, for example, 100% or less. The total light transmittance of the adhesive layer 20 can be measured according to JIS K 7375 (2008).

The adhesive layer 30 is a pressure-sensitive adhesive layer formed from the second adhesive composition. The adhesive layer 30 has transparency. The second PSA composition contains at least a base polymer. Examples of the base polymer contained in the second pressure-sensitive adhesive composition include the base polymers described above with respect to the first pressure-sensitive adhesive composition. The base polymer in the first PSA composition and the base polymer in the second PSA composition may be the same or different. The second PSA composition may contain components other than the base polymer. Examples of the components contained in the second pressure-sensitive adhesive composition include the components other than the base polymer described above for the first pressure-sensitive adhesive composition. The composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition may be the same or different.

The thickness H of the adhesive layer 30 may be the same as or different from the thickness of the adhesive layer 20. The thickness H of the pressure-sensitive adhesive layer 30 is preferably 10 μm or more, more preferably 15 μm or more, from the viewpoint of ensuring sufficient adhesion to the adherend. The thickness of the pressure-sensitive adhesive layer 30 is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less, from the viewpoint of handling. Also, the ratio of the thickness H of the adhesive layer 30 to the thickness of the adhesive layer 20 is, for example, 0.2 or more and 5 or less.

The haze of the adhesive layer 30 is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. The haze of the adhesive layer 30 can be measured using a haze meter according to JIS K7136 (2000).

The total light transmittance of the adhesive layer 30 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher. The total light transmittance of the adhesive layer 30 is, for example, 100% or less. The total light transmittance of the adhesive layer 30 can be measured according to JIS K 7375 (2008).

As the substrate 40, in this embodiment, a pixel panel for a foldable display can be used. Pixel panels include organic EL panels and liquid crystal panels. When the base material 40 is a pixel panel, the thickness of the base material 40 is, for example, 10 μm or more and, for example, 150 μm or less. The substrate 40 may be, for example, a flexible plastic film. As the plastic film, for example, a plastic film to be described later regarding the release film 50 can be used.

Examples of the release film 50 include a flexible plastic film. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. The thickness of the release film 50 is preferably 5 μm or more, more preferably 10 μm or more, and preferably 200 μm or less, more preferably 150 μm or less. The surface of the release film 50 is preferably release-treated. Release treatments include, for example, silicone release treatments and fluorine release treatments. The peel starting force F1 and the peel force F2 for peeling the peel film 50 from the pressure-sensitive adhesive layer 30 can be adjusted by the presence or absence of the peel treatment, selection of the type, and adjustment of the conditions.

The optical laminate X can be manufactured, for example, as follows.

First, the optical film 10, the adhesive layer 20 with the first release film, and the adhesive layer 30 with the second release film are prepared (preparation step).

The pressure-sensitive adhesive layer 20 with the first release film can be formed by applying the first pressure-sensitive adhesive composition (varnish) on the first release film to form a coating film, and then drying the coating film. Examples of the method of applying the first pressure-sensitive adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, Lip coating and die coating can be mentioned (the same applies to the method of applying the second pressure-sensitive adhesive composition, which will be described later). Another release film may be laminated on the adhesive layer 20 on the first release film. This peeling film is peeled off before bonding the optical film 10 and the pressure-sensitive adhesive layer 20 together.

The pressure-sensitive adhesive layer 30 with the second release film can be formed by applying the second pressure-sensitive adhesive composition (varnish) on the second release film to form a coating film, and then drying the coating film. Another release film may be laminated on the adhesive layer 30 on the second release film. This peeling film is peeled off before bonding the optical film 10 and the adhesive layer 30 together.

Next, the first surface 11 of the optical film 10 and the pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 with the first release film are bonded together (first bonding step). Next, the second surface 12 of the optical film 10 and the pressure-sensitive adhesive layer 30 side of the pressure-sensitive adhesive layer 30 with the second release film are bonded together (second bonding step). As a result, a layered body as the optical layered body X with an unprocessed outer peripheral edge is obtained. Preferably, the first surface 11 and the second surface 12 of the optical film 10, the exposed surface of the first release film-attached pressure-sensitive adhesive layer 20, and the second release film-attached pressure-sensitive adhesive layer 30 are exposed before the bonding. A face is plasma treated.

Next, the laminate is held by a jig that sandwiches the laminate in the thickness direction. It is adjusted so that it protrudes from the side end face of , to a predetermined extent (pressurization and holding step). By adjusting the applied pressure, the degree of elastic deformation of the pressure-sensitive adhesive layers 20 and 30 can be adjusted, and therefore the length protruding from the side end face of the laminate can be adjusted.

Next, while the pressure-sensitive adhesive layers 20 and 30 are elastically deformed so as to protrude from the side end face of the laminate, all or part of the outer peripheral end of the laminate is newly formed inside a predetermined length from the side end face of the laminate. (cutting step). The predetermined length is, for example, 0.1 mm or more and, for example, 1 mm or less. After that, the laminate is released from the pressurized state by the jig. As a result, the

adhesive layers

20 and 30 are elastically restored, and the

edges

22 and 32 of the

adhesive layers

20 and 30 are separated from the

edges

13, 42 and 52 of the optical film 10, the substrate 40 and the release film 50. also retreat inward in the surface direction D. In this way, the uneven side edge E is formed.

In such a cutting step, by adjusting the pressure applied to the laminate in the thickness direction, the length of the

adhesive layers

20 and 30 protruding from the side end surfaces of the laminate can be adjusted. Retraction lengths d1 and d2 of the

edges

22 and 32 after pressure release can be adjusted. As described above, adjustment of the thickness and elastic modulus of the pressure-sensitive adhesive layer 20 can also be exemplified as a method for adjusting the retraction length d1. Methods for adjusting the retraction length d2 include adjusting the thickness and elastic modulus of the pressure-sensitive adhesive layer 30, as described above. In addition, as a method for adjusting the distance between the

edges

22 and 32 in the surface direction D (that is, the difference between the retraction length d1 and the retraction length d2), as described above, the side uneven end portion E is formed. Adjustment of the cutting conditions in the cutting step, which will be described later, is carried out using a rotary blade. The cutting conditions include, for example, the taper angle of the cutting edge of the rotary blade, the number of rotations of the rotary blade, the incident direction of the rotary blade with respect to the surface of the optical film laminate described later, and the displacement of the rotary blade for cutting the optical film laminate. speed.

Next, after peeling the first release film from the adhesive layer 20 of the optical film laminate, the substrate 40 is bonded to the adhesive layer 20 exposed by the peeling (third bonding step).

As described above, the optical layered body X (optical layered body) described above can be manufactured.

The optical layered body X may be manufactured in the same manner as the above manufacturing method except for the following. In the preparation step, instead of the adhesive layer 20 with the first release film, the adhesive layer 20 with the substrate 40 is prepared, and in the first bonding step, the first surface 11 of the optical film 10 and the substrate 40 are attached. The pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 is bonded together, and the third bonding step is not performed. The optical layered body X can also be manufactured by such a method.

5A and 5B show an example of how the optical laminate X is used.

In this method, first, the release film 50 is peeled off from the adhesive layer 30 of the optical laminate X as shown in FIG. 5A. For example, with the substrate 40 side of the optical layered body X fixed on a worktable, a force is applied to the edge of the release film 50 at the uneven side edge E to release the release film 50 from the adhesive layer 30. do. Thereby, the adhesive surface 31 of the adhesive layer 30 is exposed.

At the uneven side edge E, the edge 32 of the adhesive layer 30 is retreated from the

edges

13 and 52 of the optical film 10 and the release film 50 in the surface direction D as described above. At such a side uneven end portion E, the release film 50 has a free portion 50a to which the pressure-sensitive adhesive layer 30 is not adhered, as described above with reference to FIG. Therefore, when peeling the release film 50 from the adhesive layer 30, the free portion 50a of the release film 50 is first turned up and deformed as shown by the phantom lines in FIG. In addition, the release film 50 can be separated from the edge 32 of the pressure-sensitive adhesive layer 30 by pulling the free portion 50a that has already been turned up and deformed. That is, in the peeling start process, the force (first force) for sufficiently deforming the free portion 50a of the release film 50 and the edge 32 of the adhesive layer 30 elastically deforming following the deformation of the release film 50 are applied. A force (second force) for pulling the release film 50 away from is not required at the same time. Such an optical layered body X is suitable for reducing the force required for the peel initiation process. The smaller this force is, the more the deformation of the thin optical film 10 with a thickness of 100 μm or less is suppressed in the process of starting the peeling of the release film 50 , and the crack generation at the edge of the film is suppressed.

Next, as shown in FIG. 5B, the optical film 10 and the member M (adherend) are bonded with the adhesive layer 30 interposed therebetween. The member M is, for example, one element in the laminated structure of the flexible panel. Such elements include, for example, pixel panels, touch panels, and surface protective films.

For example, in the manufacturing process of flexible panels, the optical laminate X is used as described above.

The present invention will be specifically described below with reference to examples. The invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), physical property values, parameters, etc. described below are the corresponding compounding amounts ( content), physical properties, parameters, etc., upper limits (values defined as “less than” or “less than”) or lower limits (values defined as “greater than” or “greater than”).

[Example 1]
<Production of first adhesive sheet>
A first pressure-sensitive adhesive sheet in Example 1 was produced as follows.

<Preparation of acrylic oligomer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 95 parts by mass of cyclohexyl methacrylate (CHMA), 5 parts by mass of acrylic acid (AA), and α- A mixture containing 10 parts by mass of methylstyrene dimer and 120 parts by mass of toluene as a solvent was stirred at room temperature for 1 hour under a nitrogen atmosphere. After that, 10 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator is added to the mixture to prepare a reaction solution, which is reacted at 85° C. for 5 hours under a nitrogen atmosphere. (formation of acrylic oligomers). As a result, an oligomer solution containing an acrylic oligomer (solid concentration: 50% by mass) was obtained. The acrylic oligomer had a weight average molecular weight of 4,300. Moreover, the glass transition temperature (Tg) of the acrylic oligomer was 84°C.

<Preparation of first acrylic base polymer>
70 parts by mass of 2-ethylhexyl acrylate (2EHA), 20 parts by mass of n-butyl acrylate (BA), and lauryl acrylate were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. (LA) 8 parts by mass, 4-hydroxybutyl acrylate (4HBA) 1 part by mass, N-vinyl-2-pyrrolidone (NVP) 0.6 parts by mass, and 2,2′- as a thermal polymerization initiator A mixture containing 0.1 part by mass of azobisisobutyronitrile (AIBN) and ethyl acetate as a solvent (solid concentration: 47% by mass) was stirred under a nitrogen atmosphere at 56°C for 6 hours (polymerization reaction ). This gave a first polymer solution containing the first acrylic base polymer. The weight average molecular weight of the first acrylic base polymer in this polymer solution was about 2 million.

<Preparation of first adhesive composition>
To the first polymer solution, 1.5 parts by mass of acrylic oligomer per 100 parts by mass of the solid content of the polymer solution and 0.5 parts by mass of the first cross-linking agent (product name "Nyper BMT-40SV", dibenzoyl peroxide, manufactured by NOF) were added. 26 parts by mass, a second cross-linking agent (product name "Coronate L", trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Tosoh) 0.02 parts by mass, a silane coupling agent (product name "KBM403", Shin-Etsu Kagaku Kogyo Co., Ltd.) was added and mixed to prepare a first adhesive composition.

<Formation of first adhesive sheet>
A coating film was formed by applying the first pressure-sensitive adhesive composition onto the release-treated surface of release film L1, one surface of which had been subjected to silicone release treatment. The release film L1 is a polyethylene terephthalate (PET) film (product name “Diafoil MRF50”, thickness 50 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the release-treated surface of the release film L2, one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L1. The release film L2 is a PET film (product name: “DIAFOIL MRV75”, thickness: 75 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the coating film sandwiched between the release film L1 and the release film L2 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to form a transparent first adhesive having a thickness of 50 μm. A first pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the first pressure-sensitive adhesive sheets with release films L1 and L2 were produced.

<Production of second adhesive sheet>
A second pressure-sensitive adhesive sheet in Example 1 was produced as follows.

<Preparation of second acrylic base polymer>
99 parts by mass of butyl acrylate (BA), 1 part by mass of 4-hydroxybutyl acrylate (4HBA), and thermal polymerization start in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube. A mixture containing 0.3 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as an agent and ethyl acetate as a solvent was stirred at 60° C. for 4 hours under a nitrogen atmosphere (polymerization reaction ). This gave a second polymer solution containing a second acrylic base polymer. The weight average molecular weight of the second acrylic base polymer in this polymer solution was 1,650,000.

<Preparation of second adhesive composition>
In the second polymer solution, 0.3 parts by mass of the first cross-linking agent (product name "Niper BMT-40SV", dibenzoyl peroxide, manufactured by NOF) per 100 parts by mass of the solid content of the polymer solution, and the third cross-linking agent (product name “Takenate D110N”, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals) 0.1 parts by mass and 0.3 parts by mass of a silane coupling agent (product name “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) are added and mixed. Then, a second adhesive composition was prepared.

<Formation of second adhesive sheet>
A coating film was formed by applying the second pressure-sensitive adhesive composition onto the release-treated surface of release film L3, one surface of which had been subjected to silicone release treatment. The release film L3 is a polyethylene terephthalate (PET) film (product name: "Diafoil MRF50", thickness: 50 µm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the release-treated surface of the release film L4, one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L3. The release film L4 is a PET film (product name: "DIAFOIL MRV75", thickness: 75 µm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the coating film sandwiched between the release film L3 and the release film L4 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to obtain a transparent second adhesive having a thickness of 50 μm. A second pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the second adhesive sheets with release films L3 and L4 were produced.

<Preparation of optical laminate>
First, the release film L2 was peeled off from the first pressure-sensitive adhesive sheet with a double-sided release film, and the exposed surface thereby exposed was plasma-treated. On the other hand, both surfaces (first surface and second surface) of the polarizing plate having a thickness of 31 μm were also plasma-treated. In each plasma treatment, a plasma irradiation device (product name “AP-TO5”, manufactured by Sekisui Kogyo Co., Ltd.) was used, the voltage was 160 V, the frequency was 10 kHz, and the treatment speed was 5000 mm / min (also in the plasma treatment described later similar). Then, the exposed surface of the first adhesive sheet and the first surface of the polarizing plate were bonded together. In this bonding, the first pressure-sensitive adhesive sheet with the release film L1 and the polarizing plate were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C.

Next, the release film L3 was peeled off from the second adhesive sheet with the release films L3 and L4, and the exposed surface was plasma-treated. Then, the exposed surface of the second adhesive sheet and the second surface of the polarizing plate were bonded together. In this bonding, the second pressure-sensitive adhesive sheet with the release film L4 and the polarizing plate were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C. As a result, a laminated film having a laminated configuration of a first adhesive sheet with a release film L1 (thickness of 50 μm), a polarizing plate, and a second adhesive sheet with a release film L4 (thickness of 75 μm) was obtained.

Next, using a punching machine and a Thomson blade, the laminated film was punched into a size of 150 mm x 120 mm (punching process).

Next, the outer shape was processed as follows (outer shape processing process). First, a laminate was obtained by stacking 50 laminate films punched into the same size. Specifically, in adjacent laminated films, 50 laminated films are laminated so that the release film L1 (first release film) of one laminated film and the release film L4 (second release film) of the other laminated film are in contact. The films were stacked to obtain a laminate. This laminate has one surface in the thickness direction (first surface layer surface) on which the first release film is arranged, and the other surface in the thickness direction (second surface layer surface) on which the second release film is arranged. ) and Next, this laminate was held by jigs that sandwiched in the thickness direction. Next, the pressure applied to the laminate in the thickness direction by the jig was adjusted so that each pressure-sensitive adhesive layer protrudes from the end face of the laminate to a predetermined extent. In this state, 0.5 mm inside from the end face of the laminate was cut in the thickness direction so that the outer peripheral edge of the laminate was newly formed. For cutting, a predetermined cutting machine and a first rotary blade attached to the machine were used. This rotary blade has a disk portion and a plurality of projecting blades projecting in the disk radial direction from the peripheral edge of the disk portion. As shown in FIGS. 6A and 6B, the protruding blade 70 has a linear knife edge 71 (length 6 mm) that cuts the object 80 at the edge on the front side when the rotary blade rotates. In the outer shape processing step, the rotary blades are rotated with respect to the laminate so that each protruding blade 70 cuts into the laminate (cutting target 80) from the second surface side, and the rotation speed of the rotary blade is set to 4500 rpm. , the displacement speed of the rotary blade with respect to the laminated body is 1000 mm/min, and the elevation angle (blade angle θ) of the knife edge 71 facing the laminated body just before cutting is +5° (blade angle θ) with respect to the laminated body surface (second surface layer surface) 6A) (when the blade angle θ opens outward in the disk radial direction as shown in FIG. 6A, the blade angle θ is positive, and when the blade angle θ opens inward in the disk radial direction as shown in FIG. 6B, the blade angle θ is negative. is the blade angle θ). After the outer shape processing, the laminate was released from the pressurized state by the jig.

Next, after peeling off the release film L1 from the first pressure-sensitive adhesive layer of the optical film laminate, a polyimide film (product name “Kapton”, thickness 50 μm, thickness 50 μm, Toray DuPont Co.) was pasted together.

The optical laminate of Example 1 was manufactured as described above. The optical laminate of Example 1 includes a polyimide film (thickness of 50 μm) as a substrate, a first adhesive layer (thickness of 50 μm), a polarizing plate (thickness of 31 μm) as an optical film, and a second adhesive An agent layer (thickness 50 μm) and a release film L4 (thickness 75 μm) are provided in order in the thickness direction. At the uneven side edges, the edges of the first and second pressure-sensitive adhesive layers are retreated from the edges of the films in the film surface direction. In the optical film laminate thus produced, the edges of the substrate, the optical film, and the release film are substantially at the same position in the in-plane direction of the film. Therefore, the retraction length d2′ of the edge of the second adhesive layer from the edge of the release film is substantially equal to the retraction length d2 of the edge of the second adhesive layer from the edge of the optical film. .

[Examples 2 to 4]
Optical laminates of Examples 2 to 4 were produced in the same manner as the optical laminate of Example 1 except for the following.

In Example 2, the above-described blade angle θ during contour processing was adjusted so that the absolute value was larger on the positive side than in Example 1. In Example 3, the above-mentioned blade angle θ during outer shape processing is adjusted to be more negative than in Example 1, and the above-mentioned rotary blade rotation speed during the same processing is adjusted to be lower than in Example 1. I adjusted it to be late. In Example 4, the layout of the laminate with respect to the rotary blade was reversed from that of Example 3 in the outer shape processing.

[Comparative Example 1]
An optical layered body of Comparative Example 1 was produced in the same manner as the optical layered body of Example 1, except that the outer shape processing step was not performed.

<Retraction length>
For each optical layered body in Examples 1 to 4 and Comparative Example 1, the retraction length d1 (distance from the edge of the optical film in the surface direction) of the edge of the first adhesive layer at the side uneven edge The withdrawal length d2 of the edge of the pressure-sensitive adhesive layer (the distance from the edge of the optical film in the surface direction) was examined as follows.

First, after peeling the base material from the optical laminate, the laminate (first adhesive layer/optical film/second adhesive layer/release film) is removed from the glass via the first adhesive layer exposed by the peeling. pasted on the plate. Next, the release film was peeled off from the laminate on the glass plate. A predetermined portion selected from the outer peripheral edge of the laminate (first pressure-sensitive adhesive layer/optical film/second pressure-sensitive adhesive layer) on the glass plate was observed with an optical microscope. Specifically, the laminate was observed and photographed in the thickness direction with an optical microscope from the side opposite to the glass plate. Then, in the photographed image, the retraction length d1 of the edge of the first adhesive layer from the edge of the optical film and the retraction length of the edge of the second adhesive layer from the same edge of the optical film d2 was measured. Table 1 shows the measurement results.

<Peeling initiation force and peeling force>
For each of the optical laminates in Examples 1 to 4 and Comparative Example 1, the force required for peeling the release film (the peel initiation force and the subsequent peel force) was examined.

First, a test piece for measurement (approximately 25 mm short side x 150 mm long side) was cut out from the optical layered body. Specifically, a test piece having a length of about 150 mm and a width of 25 mm was cut from the same film from the edge of the uneven side surface of the optical layered body.

Next, the test piece was fixed to the fixing table of the tensile tester (product name "Autograph", manufactured by Shimadzu Corporation). Specifically, after peeling and removing the substrate from the test piece, the test piece (first adhesive layer / optical film / second adhesive layer / release film) was attached to the fixing table.

Next, a gripping tape was attached to the short side of the release film located on the exposed surface side of the test piece, on the side of the uneven end of the side surface. This gripping tape had a strong adhesive surface, and the gripping tape was attached to the release film of the test piece via the strong adhesive surface.

Next, using a tensile tester, a peel test was conducted in which the release film on the second adhesive layer of the test piece was peeled off from the adhesive layer, and the force required for peeling was measured as the peel strength. In this measurement, the measurement temperature was 25° C., the peeling film was peeled off by pulling the gripping tape, the peeling angle was 180°, the pulling speed was 300 mm/min, and the peeling length was 100 mm. An example of a graph obtained by such a peeling test is shown in FIG. In the graph of FIG. 7, the horizontal axis represents the peel length (mm), the vertical axis represents the peel strength (gf), and Fm represents the maximum value of the peel strength.

Table 1 shows the peel starting force F1 (gf/25 mm) and the peel force F2 (gf/25 mm) determined by the above peel test. The peel starting force F1 is the maximum value of the peel strength within a peel length of 20 mm when the peel film is peeled from the second adhesive layer, and the peel force F2 is the peel length of 20 to 100 mm (the peel strength is It is the average value of the peel strength when the peel strength is stable after passing through the peel initiation force F1 at the start of peeling. In addition, regarding the suppression of the peel initiation force, the case where the peel initiation force F1 is 600 gf / 25 mm or less is evaluated as "excellent", and the case where the peel initiation force F1 exceeds 600 gf / 25 mm and is 800 gf / 25 mm or less is evaluated as "good". ", and the case where the peel initiation force F1 exceeded 800 gf/25 mm was evaluated as "poor". The evaluation results are also shown in Table 1.

<Suppression of edge cracks in optical film>
For each of the optical laminates in Examples 1 to 4 and Comparative Example 1, the resistance to crack generation at the edge of the optical film when the release film was peeled off was examined. Specifically, first, an evaluation sample was produced for each optical layered body. Next, the release film of the evaluation sample was manually peeled off. Next, the outer peripheral portion of the optical film (1 mm region from the edge) was observed with an optical microscope. A case where no crack with a length of 100 μm or more occurred in the outer peripheral portion of the optical film after peeling of the release film was evaluated as “excellent”, and a case where a crack with a length of 100 μm or more and less than 200 μm occurred was evaluated as “ It was evaluated as "good", and a case where a crack with a length of 200 μm or more was generated was evaluated as "bad". Table 1 shows the evaluation results.

<Blocking at the edge>
For each optical layered body in Examples 1 to 4 and Comparative Example 1, the difficulty of blocking at the ends was examined. Specifically, first, 10 evaluation samples were produced for each optical layered body, and the 10 evaluation samples were stacked to form a film pile (first step). Next, the adhesive surface at the tip of a cylindrical rod (10 mm in diameter) having an adhesive surface at the tip is pressed from above against the optical layered body positioned at the top of the film pile, and then the rod is pulled upward, The number of optical laminates lifted by the rod was counted (second step). A trial consisting of the first step and the subsequent second step was performed 10 times for each optical layered body. In 10 trials, the number of trials in which only one optical layered body was lifted with the rod was evaluated as "excellent" when the number of trials was 10, and when the number was 6 to 9, it was evaluated as "good". A score of 5 or less was evaluated as "poor". Table 1 shows the evaluation results.

The above-described embodiments are examples of the present invention, and the present invention should not be construed to be limited by the embodiments. Variations of the invention that are obvious to those skilled in the art are included in the following claims.

The optical layered body of the present invention is used, for example, in the manufacture of foldable display panels.

X optical film (optical laminate)
Y: optical film with adhesive layer E side uneven edge T thickness direction 10 optical film 11 first surface 12 second surface 13

edge

20, 30

adhesive layer

21, 31 adhesive surface 22 edge (first edge)
32 edge (second edge)
40 Base material 42 Edge 50 Release film 52 Edge

Claims

An optical laminate comprising a substrate, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a release film in this order in the thickness direction,
The optical film has a thickness of 100 μm or less,
In the surface direction perpendicular to the thickness direction of the optical film, the edge of the second pressure-sensitive adhesive layer is retreated from the edges of the optical film and the release film, and has a side uneven edge. , an optical laminate.
2. The optical layered body according to claim 1, wherein at the uneven side surface edge portion, the retraction length of the edge of the second pressure-sensitive adhesive layer from the edge of the release film in the surface direction is 20 μm or more.
2. The optical layered body according to claim 1, wherein at the uneven side edge portion, the edge of the first pressure-sensitive adhesive layer is receded from the edge of each of the optical film and the substrate in the planar direction. .
In the uneven end portion of the side surface, in the surface direction, the edge of the second adhesive layer from the edge of the optical film is less than the retracted length of the edge of the first adhesive layer from the edge of the optical film. 4. The optical stack of claim 3, wherein the edges have a small retraction length.
2. The optical laminate according to claim 1, wherein the distance between the edge of the first pressure-sensitive adhesive layer and the edge of the second pressure-sensitive adhesive layer in the planar direction is 1 μm or more.
2. The method according to claim 1, wherein the ratio of the retracted length of the edge of the second pressure-sensitive adhesive layer from the edge of the release film to the thickness of the second pressure-sensitive adhesive layer is 0.4 or more and 8 or less. optical laminate.
The optical layered body according to claim 1, wherein a peel initiation force for starting peeling of the release film from the second pressure-sensitive adhesive layer is 800 gf/25 mm or less.