WO2023276653A1

WO2023276653A1 - Optical film with release film

Info

Publication number: WO2023276653A1
Application number: PCT/JP2022/023778
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: JP2023006650A; KR20240028347A; TW202309562A; CN117580708A

Abstract

An optical film (X) with a release film according to the present invention is provided with an optical film (Y) with an adhesive layer, a light release film (40), and a heavy release film (50). The optical film (Y) with the adhesive layer is provided with an optical film (10) having a first surface (11) and a second surface (12) and having a thickness of 100 μm or less, an adhesive layer (20) affixed to the first surface (11) and having an adhesive surface (21), and an adhesive layer (30) affixed to the second surface (12) and having an adhesive surface (31). The light release film (40) is arranged on the adhesive surface (21), and the heavy release film (50) is arranged on the adhesive surface (31). In a lateral surface irregularity end (E) of the optical film (X), end edges (22, 32) of the adhesive layers (20, 30) are withdrawn further than end edges of the films (10, 40, 50) in an in-plane direction (D), wherein a first withdrawn length d1 of the end edge (22) is smaller than a second withdrawn length d2 of the end edge (32).

Description

Optical film with release film

The present invention relates to an optical film with a release film.

A display panel has a laminated structure including, for example, a pixel panel, a touch panel, and a transparent cover 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. The optical film is produced, for example, as an optical film with a release film in which a pressure-sensitive adhesive layer and a release film are provided on both sides of the optical film. An optical film with a release film is described, for example, in Patent Document 1 below.

JP 2020-190754 A

FIG. 6 is a schematic cross-sectional view of a film Z as an example of a conventional optical film with a release film. The film Z includes a release film 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 adhesive layer 92 is adhered to one surface of the optical film 93 . The adhesive layer 94 is adhered to the other surface of the optical film 93 . The release film 91 is attached to the adhesive layer 92 in a detachable manner. The release film 95 is attached to the adhesive layer 94 in a detachable manner. At the edge E' of the film Z, the edge 91e of the release film 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 release film 95 are flush with each other.

When such a film Z is used in the manufacturing process of a display panel, first, the peeling film 91 is peeled off from the adhesive layer 92 (first peeling step). In this step, first, at the end E′ of the film Z, a force for peeling up the release film 91 from the adhesive layer 92 is applied to the release film 91 as a load for starting peeling. This load includes the force required to sufficiently deform the release film 91 at the end E′ and the force required to separate the release film 91 from the adhesive layer 92 elastically deforming following the deformation of the release film 91. are included together. At the end E′, the end of the release film 91 is deformed so as to be separated from the edge 92 e of the pressure-sensitive adhesive layer 92 by applying such a load. Subsequently, the end of the release film 91 is pulled away from the edge 92 e so that the separation between the release film 91 and the adhesive layer 92 progresses, and the release film 91 is separated from the adhesive layer 92 . removed. After that, the optical film 93 and a first adherend (not shown) such as a pixel panel are bonded through the exposed adhesive layer 92 . Next, the release film 95 is peeled off from the adhesive layer 94 (second peeling step). Next, the optical film 93 and the second adherend (not shown) are bonded via the adhesive layer 94 exposed by the peeling.

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 film Z, the thinner the optical film 93, the easier the load for starting peeling in the first peeling step causes significant deformation of the optical film 93 at the edge E' of the film Z. Such deformation of the optical film 93 causes deformation of the adhesive layer 94 attached to the optical film 93 , and the edge 94 e of the adhesive layer 94 is separated from the release film 95 . Once the edge 94e is separated from the release film 95, separation between the adhesive layer 94 and the release film 95 tends to progress. In the first peeling step, if the separation between the adhesive layer 94 and the peeling film 95 progresses, the next step cannot be performed.

The present invention provides an optical film with a release film that is suitable for releasing a light release film from a thin optical film with a double-sided adhesive layer while suppressing release of a heavy release film.

The present invention [1] comprises an optical film having a first surface and a second surface opposite to the first surface; A pressure-sensitive adhesive layer-attached optics comprising a first pressure-sensitive adhesive layer having a surface, and a second pressure-sensitive adhesive layer attached to the second surface and having a second pressure-sensitive adhesive surface on the side opposite to the optical film a film, a light release film disposed on the first adhesive surface, and a heavy release film disposed on the second adhesive surface, wherein the optical film has a thickness of 100 μm or less, and the In the in-plane direction perpendicular to the thickness direction of the optical film, the first edge of the first pressure-sensitive adhesive layer and the The second pressure-sensitive adhesive layer has an uneven side edge where the second edge is retracted, and at the uneven side edge, the first edge is retracted from the edge of the light release film by a first retraction length. An optical film with a release film having a length smaller than a second withdrawal length of the second edge from the edge of the heavy release film.

As described above, at the side uneven end portion of the optical film with a release film of the present invention, the first adhesive is more likely than the edges of the optical film, the light release film, and the heavy release film in the in-plane direction of the optical film. A first edge of the agent layer is retracted. At such an uneven side edge, the light release film has a free portion to which the first pressure-sensitive adhesive layer is not adhered. Therefore, at the uneven end of the side surface, when peeling the light release film from the first adhesive layer, first, the free part of the light release film is turned up and deformed, and then the light release film that has already been turned up and deformed. The easy release film can be separated from the first edge of the first adhesive layer by pulling the edge of the adhesive layer. That is, in the peeling initiation process, a force (first force) for sufficiently deforming the end of the light release film, and the first end of the first adhesive layer that elastically deforms following the deformation of the light release film The force (second force) for pulling the light release film away from the edge is not required at the same time (in contrast to the film Z described above, the first force and the second force are required at the same time, Therefore, a large force is required for the peel initiation process). Such an optical film with a release film is suitable for reducing the force required for the release initiation process. The smaller this force is, the more the deformation of the thin optical film with a thickness of 100 μm or less is suppressed and the deformation of the second adhesive layer is suppressed in the process of starting the peeling of the light release film. The edge is suppressed from separating from the heavy release film.

In addition, at the side uneven end portion of the optical film with this release film, as described above, the first retraction length (from the edge of the light release film in the in-plane direction of the film to the first edge of the first adhesive layer) distance) is smaller than the second withdrawal length (the distance from the edge of the heavy release film to the second edge of the second pressure-sensitive adhesive layer in the in-plane direction of the film). That is, at the uneven side edge, the second edge of the second pressure-sensitive adhesive layer is retreated from the first edge of the first pressure-sensitive adhesive layer in the in-plane direction of the film. In such a configuration, in the process of starting peeling of the light release film, the second force for separating the light release film from the first edge of the first adhesive layer acts on the optical film with the release film. Sometimes, it is suitable for suppressing deformation of the second pressure-sensitive adhesive layer, and therefore suitable for suppressing separation of the second edge of the second pressure-sensitive adhesive layer from the heavy release film.

The present invention [2] includes the optical film with a release film according to [1] above, wherein the distance between the first edge and the second edge in the in-plane direction is 1 μm or more.

Such a configuration is preferable for suppressing the above-described deformation of the second adhesive layer in the process of starting peeling of the light release film, so that the second edge of the second adhesive layer is separated from the heavy release film. is preferable for suppressing

The present invention [3] includes the optical film with a release film according to the above [1] or [2], wherein the first withdrawal length is 20 μm or more.

In such a configuration, in the process of starting peeling of the light release film, before the light release film is separated from the first edge of the first adhesive layer, the end of the light release film (the free portion) is sufficiently It is suitable for turning up and deforming, and is therefore preferable for reducing the force (total force) required to initiate peeling of a light release film.

The present invention [4] is any one of [1] to [3] above, wherein the ratio of the first withdrawal length to the thickness of the first pressure-sensitive adhesive layer is 0.4 or more and 8 or less. including optical films with release films.

In such a configuration, in the process of starting peeling of the light release film, before the light release film is separated from the first edge of the first adhesive layer, the end of the light release film (the free portion) is sufficiently It is suitable for flipping up and deforming, and is therefore preferred for reducing the force required to initiate peeling of a light release film.

In the present invention [5], the first peel initiation force for initiating peeling of the light release film from the first adhesive surface is a force for initiating peeling of the heavy release film from the second adhesive surface. The optical film with a release film according to any one of the above [1] to [4] having a force smaller than the second release initiation force is included.

The present invention [6] includes the optical film with a release film according to [5] above, wherein the ratio of the first peel initiation force to the second peel initiation force is 0.8 or less.

The present invention [7] includes the optical film with a release film according to [6] above, wherein the first peel initiation force is less than 800 gf/25 mm.

Such a configuration is preferable for suppressing the separation of the second edge of the second pressure-sensitive adhesive layer from the heavy release film and reducing the load on the optical film in the process of starting the release of the light release film.

The present invention [8] includes the optical film with a release film according to [6] or [7] above, wherein the second peel initiation force is 800 gf/25 mm or less.

Such a configuration prevents the second edge of the second adhesive layer from separating from the heavy release film in the process of starting peeling of the light release film, while peeling the heavy release film from the second adhesive layer. It is preferable to reduce the load on the optical film during the initiation process.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of one Embodiment of the optical film with a peeling film of this invention. 2 is a partially enlarged cross-sectional schematic view of the optical film with a release film shown in FIG. 1. FIG. An example of how to use the optical film with a release film of the present invention is shown. 3A shows the first peeling step of peeling the light release film, FIG. 3B shows the first bonding step of bonding the optical film and the first adherend via the first adhesive layer, and FIG. 3C. represents the second peeling step of peeling the heavy release film, and FIG. 3D represents the second bonding step of bonding the optical film and the second 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 film with a peeling film.

Optical film X as an embodiment of the optical film with release film of the present invention comprises, as shown in FIG. (heavy release liner) are provided in order in the thickness direction T. The optical film X extends in an in-plane direction D perpendicular to the thickness direction T. As shown in FIG. The pressure-sensitive adhesive layer-attached optical film Y is an element arranged at a light-passing position in the foldable device. Foldable devices include, for example, foldable display panels. A foldable display panel has a laminated structure including, for example, a pixel panel, a touch panel, a cover film, and the like. An optical film having a predetermined optical function may be provided in the laminated structure of the foldable display panel. Examples of optical films include film-like polarizing plates and retardation films. The pressure-sensitive adhesive layer-attached optical film Y is used as a supply material for the optical films included in the laminate structure in the process of manufacturing a foldable display panel.

The optical film Y with an adhesive layer includes an optical film 10 having a thickness of 100 μm or less, an adhesive layer 20 (first adhesive layer), and an adhesive layer 30 (second adhesive layer). The optical film 10 has a first surface 11 and a second surface 12 opposite to the first surface 11 . The adhesive layer 20 adheres to the first surface 11 and has an adhesive surface 21 (first adhesive surface) on the side opposite to the optical film 10 . A light release film 40 is arranged on the adhesive surface 21 . The adhesive layer 30 adheres to the second surface 12 and has an adhesive surface 31 (second adhesive surface) on the side opposite to the optical film 10 . The heavy release film 50 is arranged on the adhesive surface 31 . In addition, as edges that define the outline shape in plan view, the optical film 10 has an edge 13, the adhesive layer 20 has an edge 22 (first edge), and the adhesive layer 30 has an edge 32 (second edge), the light release film 40 has an edge 42 and the heavy release film 50 has an edge 52 .

The optical film X has a side uneven edge E as shown in FIG. 2 on all or part of the outer peripheral edge of the film. At the side surface uneven edge E, the

edges

22, 32 of the

adhesive layers

20, 30 are positioned more than the

edges

13, 42, 52 of the optical film 10, the light release film 40, and the heavy release film 50 in the in-plane direction D. is evacuating. In addition, at the uneven side edge E, the first withdrawal length d1 of the edge 22 of the adhesive layer 20 from the edge 42 of the light release film 40 is the same as the edge 52 of the heavy release film 50. is smaller than the second retraction length d2 of the edge 32 of the . The first retraction length d1 is the distance between the

edges

22, 42 in the in-plane direction D. As shown in FIG. The second retraction length d2 is the distance between the

edges

32, 52 in the in-plane direction D. As shown in FIG. Methods for adjusting the first retraction length d1 include, for example, adjusting the thickness of the pressure-sensitive adhesive layer 20 and adjusting the elastic modulus. Methods for adjusting the second retraction length d2 include, for example, adjusting the thickness and modulus of the adhesive layer 30 . Further, as a method of adjusting the distance between the

edges

22 and 32 in the in-plane direction D (that is, the difference between the first retraction length d1 and the second retraction length d2), for example, forming the uneven side edge E Adjustment of the cutting conditions in the cutting step, which will be described later, is carried out using a rotary blade in order to achieve this. 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.

At the side uneven edge E of the optical film X, as described above, in the in-plane direction D, the pressure-sensitive adhesive layer is formed more than the

edges

13, 42, 52 of the optical film 10, the light release film 40, and the heavy release film 50. The edge 22 of 20 is retracted. At such a side uneven end portion E, the light release film 40 has a free portion 40a to which the pressure-sensitive adhesive layer 20 is not adhered. Therefore, when peeling the light release film 40 from the adhesive layer 20 at the uneven side edge E, first, the free portion 40a of the light release film 40 is turned up and deformed as shown by the phantom lines in FIG. After that, the free portion 40a that has already been turned up and deformed can be pulled to separate the light release film 40 from the edge 22 of the pressure-sensitive adhesive layer 20.例文帳に追加That is, in the process of starting peeling, the force (first force) for sufficiently deforming the free portion 40a of the light release film 40 and the edge of the adhesive layer 20 that elastically deforms following the deformation of the light release film 40 A force (second force) for pulling the light release film 40 away from the edge 22 is not required at the same time. Such an optical film 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 and the deformation of the adhesive layer 30 is suppressed in the peeling start process of the light release film 40. Therefore, the edge of the adhesive layer 30 is suppressed. 32 is suppressed from separating from the heavy release film 50 .

Also, at the side uneven end portion E of the optical film X, the first retraction length d1 is smaller than the second retraction length d2 as described above. That is, the edge 32 of the adhesive layer 30 is retreated from the edge 22 of the adhesive layer 20 in the in-plane direction D at the uneven side edge portion E. With this configuration, when the second force for separating the light release film 40 from the edge 22 of the adhesive layer 20 acts on the optical film X in the process of starting peeling of the light release film 40, the adhesive It is suitable for suppressing deformation of the adhesive layer 30 and therefore suitable for suppressing separation of the edge 32 of the pressure-sensitive adhesive layer 30 from the heavy release film 50 .

As described above, the optical film X is suitable for peeling the light release film 40 from the thin optical film 10 with the

adhesive layers

20 and 30 while suppressing the peeling of the heavy release film 50 .

In the optical film X, the distance between the

edges

22 and 32 in the in-plane direction D 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 detachment initiation process of the light release film 40, and therefore the edge 42 of the adhesive layer 40 separates from the heavy release film 50. It is preferable to suppress Also, the distance between the

edges

22 and 32 in the in-plane 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 reduces 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 first withdrawal length d1 is preferably 20 μm or longer, more preferably 40 μm or longer, and even more preferably 60 μm or longer. In such a configuration, the free portion 40a of the light release film 40 is sufficiently turned over before the light release film 40 is separated from the edge 22 of the adhesive layer 20 in the process of starting the peeling of the light release film 40. It is suitable for raising and deforming, and is therefore preferable for reducing the force (total force) required to start peeling the light release film 40 . Also, the first withdrawal length d1 is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less. The second retraction length d2 is preferably 21 μm or more, more preferably 41 μm or more, and even more preferably 61 μm or more, as long as it is greater than the first retraction length d1. The second retraction length d2 is preferably 550 μm or less, more preferably 450 μm or less, and even more preferably 350 μm or less, as long as it is greater than the first retraction length d1. The ratio (d2/d1) of the second retraction length d2 to the first retraction length d1 is preferably 1.1 or more, more preferably 1.2 or more. The ratio (d2/d1) is preferably 5 or less, more preferably 4 or less.

The first peel starting force F1 for starting peeling of the light release film 40 from the adhesive surface 21 of the adhesive layer 20 preferably starts peeling of the heavy release film 50 from the adhesive surface 31 of the adhesive layer 30. is smaller than the second peel initiation force F2 for The ratio (F1/F2) of the first peel initiation force F1 to the second peel initiation force F2 is preferably 0.8 or less, more preferably 0.78 or less. The ratio (F1/F2) is preferably 0.1 or more, more preferably 0.15 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 light release film 40, and therefore suppress the edge 32 of the adhesive layer 30 from separating from the heavy release film 50. preferred.

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 first peel initiation force F1 is preferably less than 800 gf/25 mm, more preferably 500 gf/25 mm or less, even more preferably 400 gf/25 mm or less. Such a configuration is preferable for suppressing separation of the edge 32 of the adhesive layer 30 from the heavy release film 50 and reducing the load on the optical film 10 in the process of starting the release of the light release film 40 . Also, the first peel initiation force F1 is preferably 5 gf/25 mm or more, more preferably 10 gf/25 mm or more, and even more preferably 20 gf/25 mm or more. Such a configuration is preferable for suppressing lifting (partial peeling) of the light release film 40 from the adhesive layer 20 during transportation and handling of the optical film X, for example.

The peeling force f1 for peeling the light release film 40 from the adhesive surface 21 of the adhesive layer 20 after the peeling of the light release film 40 from the adhesive layer 20 is started is preferably 0.1 gf/25 mm or more, more preferably It is 0.3 gf/25 mm or more, more preferably 0.5 gf/25 mm or more. The peel force f1 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.

The second peel initiation force F2 is preferably 800 gf/25 mm or less, more preferably 700 gf/25 mm or less, still more preferably 600 gf/25 mm or less. Such a configuration suppresses separation of the edge 32 of the adhesive layer 30 from the heavy release film 50 in the peeling start process of the light release film 40, while peeling the heavy release film 50 from the adhesive layer 30. It is preferable to reduce the load on the optical film 10 during the starting process. Also, the second peel initiation force F2 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 heavy release film 50 from the adhesive layer 30 during transportation and handling of the optical film X, for example.

The peeling force f2 for peeling the heavy release film 50 from the adhesive surface 31 of the adhesive layer 30 after the heavy release film 50 starts to be peeled from the adhesive layer 30 is preferably 0.1 gf/25 mm or more, more preferably It is 0.3 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. Also, the ratio (f1/f2) of the above-mentioned peeling force f1 to the peeling force f2 is preferably 0.8 or less, more preferably 0.7 or less. The ratio (f1/f2) is preferably 0.1 or more, more preferably 0.2 or more.

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, 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 device from being corroded by acid components, the adhesive layer 20 preferably has a low 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 H 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 H 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 ratio (d1/H) of the first withdrawal length d1 to the thickness H is preferably 0.4 or more, more preferably 0.6 or more. The ratio (d1/H) is preferably 8 or less, more preferably 6 or less. In these configurations, in the process of starting peeling of the light release film 40, before the light release film 40 is separated from the edge 22 of the pressure-sensitive adhesive layer 20, the ends of the light release film 40 (the above-mentioned free portions 40a) are sufficiently peeled off. It is suitable for turning up and deforming, and is therefore preferable for reducing the force required to initiate peeling of the light release film 40 .

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. From the viewpoint of adjusting the peel initiation forces F1 and F2 and the peel forces f1 and f2 described above, it is preferable that the composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition are different.

The thickness of the adhesive layer 30 may be the same as or different from the thickness of the adhesive layer 20. The thickness 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 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).

Examples of the light release film 40 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 light release film 40 is preferably 5 μm or more, more preferably 10 μm or more, and is preferably 200 μm or less, more preferably 150 μm or less. The surface of the light release film 40 is preferably release treated. Examples of the release treatment include silicone release treatment and fluorine release treatment (the same applies to the release treatment described below). The above-described first peel starting force F1 and peeling force f1 for peeling the light release film 40 from the adhesive layer 20 can be adjusted by adjusting the presence or absence of the peeling treatment, the type of peeling treatment, and the adjustment of the conditions.

Examples of the heavy release film 50 include the plastic films described above with respect to the light release film 40 . The thickness of the heavy release film 50 is preferably 5 μm or more, more preferably 10 μm or more, and is preferably 200 μm or less, more preferably 150 μm or less. The surface of the heavy release film 50 is preferably release treated. The above-described second peel starting force F2 and peeling force f2 for peeling the heavy release film 50 from the pressure-sensitive adhesive layer 30 can be adjusted by selecting the presence or absence of the peeling treatment, selecting the type, and adjusting the conditions.

The optical film X can be produced, for example, as follows.

First, the optical film 10, the adhesive layer 20 with the light release film 40, and the adhesive layer 30 with the heavy release film 50 are prepared (preparation step).

The adhesive layer 20 with the light release film 40 can be formed by applying the first adhesive composition (varnish) on the light release film 40 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 light release film 40 . 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 heavy release film 50 can be formed by applying the second pressure-sensitive adhesive composition (varnish) on the heavy release film 50 to form a coating film, and then drying the coating film. Another release film may be laminated on the adhesive layer 30 on the heavy release film 50 . 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 adhesive layer 20 side of the adhesive layer 20 with the light release film 40 are laminated together (first laminating 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 heavy release film 50 are pasted together (second pasting step). As a result, a laminate as the optical film X with an unprocessed outer peripheral edge is obtained. Preferably, before these bonding, the first surface 11 and the second surface 12 of the optical film 10, the exposed surface of the adhesive layer 20 with the light release film 40, and the exposure of the adhesive layer 30 with the heavy release film 50 are exposed. 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 aligned with the

edges

13 and 42 of the optical film 10, the light release film 40, and the heavy release film 50. It retreats inward in the in-plane direction D from 52 . 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. Further, as a method for adjusting the first retraction length d1, adjustment of the thickness and adjustment of the elastic modulus of the pressure-sensitive adhesive layer 20 can be mentioned as described above. Methods for adjusting the second 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 in-plane direction D (that is, the difference between the first retraction length d1 and the second retraction length d2), the side uneven end portion Adjustment of the cutting conditions in the cutting step, which is performed using a rotating blade to form 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.

As described above, the above optical film X (optical film with release film) can be produced.

In the above-described preparation step, the release film for the first process is used instead of the light release film 40 to prepare the adhesive layer 20 with the release film for the first process, and the heavy release film 50 is replaced by the second process. You may prepare the adhesive layer 30 with a peeling film for a 2nd process using the peeling film for. In this case, in the above-described first bonding step, 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 release film for the first step are bonded together. In the second bonding step, 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 a release film for the second step are bonded together (preferably before bonding, performs the plasma treatment described above). As a result, a laminate having the first process release film, the pressure-sensitive adhesive layer 20, the optical film 10, the pressure-sensitive adhesive layer 30, and the second process release film in order in the thickness direction is obtained. Then, in the laminate, after peeling off the first process release film from the adhesive layer 20, the light release film 40 is attached to the exposed surface of the adhesive layer 20, and the second process release film is attached to the adhesive layer. After peeling from the layer 30 , the heavy release film 50 is attached to the exposed surface of the pressure-sensitive adhesive layer 30 . As described above, a laminate as the optical film X having an unprocessed outer peripheral edge may be obtained. After that, the laminate is subjected to the pressure holding step and the cutting step described above, whereby the optical film X (the optical film with the release film) can be produced.

In the manufacturing process of the optical film X, in the first lamination step, the pressure-sensitive adhesive layer 20 with the release film for the first step is laminated to the first surface 11 of the optical film 10, while in the second lamination step, The pressure-sensitive adhesive layer 30 with the release film 50 may be laminated to the second surface 12 of the optical film 10 (preferably, the above-described plasma treatment is performed before lamination). As a result, a laminate having the release film for the first process, the adhesive layer 20, the optical film 10, the adhesive layer 30, and the heavy release film 50 in order in the thickness direction is obtained. Then, in the laminate, after peeling off the first process release film from the adhesive layer 20 , the light release film 40 is attached to the exposed surface of the adhesive layer 20 . As described above, a laminate as the optical film X having an unprocessed outer peripheral edge may be obtained. After that, the laminate is subjected to the pressure holding step and the cutting step described above, whereby the optical film X (the optical film with the release film) can be produced.

In the manufacturing process of the optical film X, in the first bonding step, the pressure-sensitive adhesive layer 20 with the light release film 40 is bonded to the first surface 11 of the optical film 10, while in the second bonding step, the second step The pressure-sensitive adhesive layer 30 with a release film for optical film 10 may be laminated to the second surface 12 of the optical film 10 (preferably, the plasma treatment described above is performed before lamination). As a result, a laminate having the light release film 40, the adhesive layer 20, the optical film 10, the adhesive layer 30, and the second process release film in order in the thickness direction is obtained. Then, in the laminate, after peeling the second process release film from the adhesive layer 30 , the heavy release film 50 is attached to the exposed surface of the adhesive layer 30 . As described above, a laminate as the optical film X having an unprocessed outer peripheral edge may be obtained. After that, the laminate is subjected to the pressure holding step and the cutting step described above, whereby the optical film X (the optical film with the release film) can be produced.

In the process of manufacturing the optical film X, the

adhesive layers

20 and 30 may be formed using a photocurable adhesive composition as the adhesive composition. Examples of the photocurable pressure-sensitive adhesive composition include an ultraviolet-curable pressure-sensitive adhesive composition in which the polymerization reaction of the contained monomer component proceeds upon irradiation with ultraviolet light. For example, when a photocurable adhesive composition is used as the second adhesive composition, first, the second adhesive composition is applied onto the release film for the second step to form a coating film. Next, the heavy release film 50 is laminated on the coating film on the release film for the second step. Next, by irradiating the coating film between the release films with light of a predetermined wavelength (such as ultraviolet rays), the coating film is photocured. Thereby, the pressure-sensitive adhesive layer 30 is formed between the release films. Next, the release film for the second process is peeled off from the adhesive layer 30 on the heavy release film 50 . Using the pressure-sensitive adhesive layer 30 with the heavy release film 50 thus obtained, the above-described second bonding step may be performed.

3A to 3D show an example of how the optical film X is used.

In this method, first, the light release film 40 is peeled off from the adhesive layer 20 of the optical film X as shown in FIG. 3A. For example, with the heavy release film 50 side of the optical film X fixed on a worktable, a force is applied to the end of the light release film 40 at the side uneven end E to remove the light release film 40 from the adhesive layer 20. peel off. Thereby, the adhesive surface 21 of the adhesive layer 20 is exposed.

As described above, in the in-plane direction D, the edges of the pressure-sensitive adhesive layer 20 are more likely than the

edges

13, 42, and 52 of the optical film 10, the light release film 40, and the heavy release film 50 at the uneven side edge E. 22 are evacuated. At such a side uneven end portion E, the light release film 40 has a free portion 40a to which the pressure-sensitive adhesive layer 20 is not adhered, as described above with reference to FIG. Therefore, when peeling the light release film 40 from the adhesive layer 20 at the uneven side edge E, first, the free portion 40a of the light release film 40 is turned up and deformed as shown by the phantom lines in FIG. After that, the free portion 40a that has already been turned up and deformed can be pulled to separate the light release film 40 from the edge 22 of the pressure-sensitive adhesive layer 20.例文帳に追加That is, in the process of starting peeling, the force (first force) for sufficiently deforming the free portion 40a of the light release film 40 and the edge of the adhesive layer 20 that elastically deforms following the deformation of the light release film 40 A force (second force) for pulling the light release film 40 away from the edge 22 is not required at the same time. Such an optical film 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 and the deformation of the adhesive layer 30 is suppressed in the peeling start process of the light release film 40. Therefore, the edge of the adhesive layer 30 is suppressed. 32 is suppressed from separating from the heavy release film 50 .

In addition, at the side uneven end portion E, as shown in FIG. 2, the first retraction length d1 is smaller than the second retraction length d2. That is, the edge 32 of the adhesive layer 30 is retreated from the edge 22 of the adhesive layer 20 in the in-plane direction D at the uneven side edge portion E. With this configuration, when the second force for separating the light release film 40 from the edge 22 of the adhesive layer 20 acts on the optical film X in the process of starting peeling of the light release film 40, the adhesive It is suitable for suppressing deformation of the adhesive layer 30 and therefore suitable for suppressing separation of the edge 32 of the pressure-sensitive adhesive layer 30 from the heavy release film 50 .

Next, as shown in FIG. 3B, the optical film 10 and the first member M1 (first adherend) are bonded with the adhesive layer 20 interposed therebetween. The first member M1 is, for example, one element in the laminated structure of the flexible panel. Examples of such elements include a pixel panel, a touch panel, and a transparent cover film (the same applies to the second member M2 described later).

Next, as shown in FIG. 3C, the heavy release film 50 is peeled off from the adhesive layer 30. Thereby, the adhesive surface 31 of the adhesive layer 30 is exposed.

Next, as shown in FIG. 3D, the optical film 10 and the second member M2 (second adherend) are bonded with the adhesive layer 30 interposed therebetween.

For example, in the manufacturing process of flexible panels, the optical film 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>
The first pressure-sensitive adhesive composition was applied onto the release-treated surface of release film L1, one surface of which was subjected to silicone release treatment, to form a coating film. 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 film with release film>
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. 4A and 4B, 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 (object to be cut 80) so that each projecting blade 70 cuts into the laminate (cutting object 80) from the first 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 immediately before cutting is -5° with respect to the laminated body surface (first surface layer surface). (Fig. 4B). (assuming a negative blade angle θ). After the outer shape processing, the laminate was released from the pressurized state by the jig.

An optical film with a release film of Example 1 was produced as described above. This optical film with a release film includes a first release film (release film L1) as a light release film, a first adhesive layer (first adhesive sheet), a polarizing plate as an optical film, and a second adhesive layer. (Second adhesive sheet) and a second release film (release film L4) as a heavy release film are provided in order in the thickness direction, and have uneven side edges over the entire outer peripheral edge. At the uneven side edge, the edges of the first and second pressure-sensitive adhesive layers are retreated from the edges of each film in the in-plane direction of the film. Further, in the optical film with a release film produced as described above, the edges of the first release film, the optical film, and the second release film are substantially at the same position in the in-plane direction of the film. . That is, at the side uneven end portion of the optical film with the release film, the first withdrawal length d1 of the first edge of the first pressure-sensitive adhesive layer from the edge of the first release film is the distance from the edge of the optical film. The retraction length d1′ of the first edge of the first adhesive layer is substantially equal, and the second retraction length d2 of the second edge of the second adhesive layer from the edge of the second release film is It is substantially equal to the retraction length d2' of the second edge of the second pressure-sensitive adhesive layer from the edge of the optical film.

[Examples 2 to 6]
Optical films with release films of Examples 2 to 6 were produced in the same manner as the optical film with release film of Example 1 except for the following.

Regarding the above-mentioned blade angle θ during external machining, in Examples 3 and 4, the absolute value was adjusted to be larger on the negative side than in Example 1, and in Example 2, it was adjusted to be further on the negative side than in Examples 3 and 4. The absolute value was adjusted to be larger, and in Example 6, the absolute value was adjusted to be larger on the negative side than in Example 2. Further, in Example 5, the above-mentioned blade angle θ during contour processing was adjusted to be more positive than in Example 1, and the above-described rotary blade displacement speed during the same processing was adjusted to adjusted to be slower than

[Example 7]
An optical film with a release film of Example 7 was produced in the same manner as the optical film with a release film of Example 1, except that a polarizing plate with a thickness of 80 µm was used instead of the polarizing plate with a thickness of 31 µm.

[Example 8]
An optical film with a release film of Example 7 was produced in the same manner as the optical film with a release film of Example 1, except that a polarizing plate with a thickness of 100 µm was used instead of the polarizing plate with a thickness of 31 µm.

[Comparative Example 1]
An optical film with a release film of Comparative Example 1 was produced in the same manner as the optical film with a release film of Example 1, except that the operations after the punching process described above were not performed.

[Comparative Example 2]
An optical film with a release film of Comparative Example 2 was produced in the same manner as the optical film with a release film of Example 1 except for the following.

A second rotary blade was used in place of the first rotary blade. 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. In the outer shape processing step, the rotary blade is rotated with respect to the laminate so that each projecting blade 70 cuts into the laminate (cutting object 80) from the second surface side (that is, the laminate with respect to the rotary blade The arrangement mode is opposite to that of Example 1), the rotation speed of the rotary blade is 4500 rpm, the displacement speed of the rotary blade with respect to the laminate is 1000 mm / min, and the knife edge faces the laminate immediately before cutting. 71 (length 6 mm) with respect to the laminate surface (second surface layer surface) (blade angle θ) was set to +5° (Fig. 4A).

<Retraction length>
For each optical film with a release film (optical film with a double-sided release film) in Examples 1 to 8 and Comparative Examples 1 and 2, the first withdrawal length d1 of the first edge of the first adhesive layer and the second adhesive The second withdrawal length d2 of the second edge of the agent layer was examined as follows.

First, after peeling off the first release film from the optical film with double-sided release film, the optical film with single-sided release film was attached to the glass plate via the first adhesive layer exposed by the peeling. Next, the second release film was peeled off from the optical film (optical film with double-sided pressure-sensitive adhesive layer) on the glass plate. A predetermined portion selected from the outer peripheral edge of the optical film with the double-sided pressure-sensitive adhesive layer on the glass plate was observed with an optical microscope. Specifically, the optical film with double-sided pressure-sensitive adhesive layers was observed and photographed with an optical microscope from the side opposite to the glass plate in the thickness direction of the optical film with double-sided pressure-sensitive adhesive layers. Then, in the photographed image, the retraction length d1 ' of the first edge of the first adhesive layer from the edge of the optical film and the second edge of the second adhesive layer from the same edge of the optical film The edge retraction length d2' was measured. The measurement results are shown in Table 1 as retracted length d1 (μm) and retracted length d2 (μm) (as described above, retracted length d1′ is substantially equal to retracted length d1 and retracted length d2' is substantially equal to the retraction length d2).

<Peeling initiation force and peeling force>
For each optical film with a release film in Examples 1 to 8 and Comparative Examples 1 and 2, the force required for peeling each release film (peeling initiation force and subsequent peeling 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 film with the release film. Specifically, a test piece having a length of about 150 mm and a width of 25 mm was cut from the optical film with a release film from the edge of the uneven side surface.

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 one release film (first release film or second release film) from the test piece, the test piece is fixed to the table through the adhesive layer exposed by the peeling. pasted on.

Next, a gripping tape was attached to the short side of the side uneven end portion of the other release film (second release film or first release film) located on the exposed surface side of the test piece. 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 peeling test was conducted in which the peeling film of the pressure-sensitive adhesive layer of the test piece was peeled off from the pressure-sensitive 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. 5, 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.

The peel initiation forces F1, F2 (gf/25 mm) and the peel strengths f1, f2 (gf/25 mm) determined by the above peel tests are shown in Table 1 (however, the peel initiation forces for Examples 7 and 8 F1 and F2 are unmeasured). The peel initiation force F1 is the maximum value of the peel strength within a peel length of 20 mm when the first peel film is peeled from the first adhesive layer, and the peel force f1 is the peel length of 20 to 100 mm (peel strength is stable after passing through the peel initiation force F1 at the start of peeling). The peel starting force F2 is the maximum value of the peel strength within a peel length of 20 mm when the second peel film is peeled from the second adhesive layer, and the peel force f2 is the peel length of 20 to 100 mm (peel strength is stable after passing through the peel initiation force F2 at the start of peeling).

<Suppression of peeling of heavy release film when peeling off light release film>
For each optical film with a release film in Examples 1 to 8 and Comparative Examples 1 and 2, the difficulty of peeling the heavy release film when peeling off the light release film was examined. Specifically, first, 10 sheets of evaluation samples were produced for each optical film with a release film. Next, the light release film of each evaluation sample was peeled off. For peeling, a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation) was used. For peeling, the peeling angle was 180° and the tensile speed was 300 mm/min. Then, when the number of evaluation samples in which only the light release film could be properly peeled without causing the peeling of the heavy release film was 10, it was evaluated as “excellent”, and when it was 7 to 9, it was evaluated as “good”. A score of 0 to 6 was evaluated as "poor". Table 1 shows the evaluation results.

<Suppression of edge cracks in optical film>
For each optical film with a release film in Examples 1 to 8 and Comparative Examples 1 and 2, the resistance to occurrence of cracks at the edges of the optical film was examined when the light release film was peeled off. Specifically, first, an evaluation sample was produced for each optical film with a release film. Next, the light 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. Then, a case where a crack with a length of 200 μm or more did not occur in the outer peripheral portion of the optical film after peeling of the light release film was evaluated as “excellent”, and a case where a crack with a length of 200 μm or more occurred was evaluated as “bad”. ” was evaluated.

<Blocking at the edge>
For each optical film with a release film in Examples 1 to 8 and Comparative Examples 1 and 2, the difficulty of blocking at the edges was examined. Specifically, first, ten evaluation samples were produced for each optical film with a release film, and the ten 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 film with a release film positioned at the top of the film pile, and then the rod is pulled upward. Then, the number of the release film-attached optical films lifted up 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 film with a release film. In 10 trials, the number of trials in which only one optical film with a release film was lifted with the rod was evaluated as "excellent" when the number of trials was 10, and "good" when the number was 6 to 9. , and the case 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 film with a release film of the present invention is used, for example, as a supply material for the optical film included in the laminated structure of the foldable display panel in the manufacturing process of the same panel.

X optical film (optical film with release film)
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 light release film 42 edge 50 heavy release film 52 edge

Claims

an optical film having a first surface and a second surface opposite the first surface;
a first pressure-sensitive adhesive layer attached to the first surface and having a first pressure-sensitive adhesive surface on the side opposite to the optical film;
an optical film with an adhesive layer, comprising: a second adhesive layer attached to the second surface and having a second adhesive surface on the opposite side of the optical film;
A light release film disposed on the first adhesive surface;
and a heavy release film disposed on the second adhesive surface,
The optical film has a thickness of 100 μm or less,
In the in-plane direction perpendicular to the thickness direction of the optical film, the first edge of the first pressure-sensitive adhesive layer and the Having a side uneven edge where the second edge of the second adhesive layer is retracted,
In the uneven side surface portion, the first retraction length of the first edge from the edge of the light release film is smaller than the second retraction length of the second edge from the edge of the heavy release film. , optical film with release film.
The optical film with a release film according to claim 1, wherein the distance between the first edge and the second edge in the in-plane direction is 1 µm or more.
The optical film with a release film according to claim 1, wherein the first withdrawal length is 20 µm or more.
The optical film with a release film according to claim 1, wherein the ratio of the first withdrawal length to the thickness of the first pressure-sensitive adhesive layer is 0.4 or more and 8 or less.
A first peel initiation force for starting peeling of the light release film from the first adhesive surface is smaller than a second peel initiation force for starting peeling of the heavy release film from the second adhesive surface. The optical film with a release film according to any one of claims 1 to 4.
The optical film with a release film according to claim 5, wherein the ratio of said first peel initiation force to said second peel initiation force is 0.8 or less.
The optical film with a release film according to claim 6, wherein the first peel initiation force is less than 800 gf/25 mm.
The optical film with a release film according to claim 6, wherein the second peel initiation force is 800 gf/25 mm or less.