JP2022137720A - Adhesive sheet, repeated bending laminate member and repeated bending device - Google Patents

Abstract

To provide an adhesive sheet capable of suppressing generation of peeling in an interface between an adhesive layer and an adherent, even when applying to a repeated bending device to bend for a long time, a repeated bending laminate member capable of suppressing generation of peeling in the interface between the adhesive layer and the adherent even when bending for a long time, and a repeated bending device.SOLUTION: An adhesive sheet 1 having an adhesive layer 11 for bonding one flexible member and another flexible member constituting a device that is repeatedly bent, where the adhesive layer 11 is formed by laminating a first adhesive layer 111 and a second adhesive layer 112, and the adhesive strength of the second adhesive layer 112 side at 23°C. is relatively greater than the adhesive strength of the first adhesive layer 111 side. The storage elastic modulus G'(-20) of the adhesive as a whole of the adhesive layer 11 at -20°C. is 0.1 MPa or less, and the adhesive layer 1 is formed such that the first adhesive layer 111 is outside and the second adhesive layer 112 is inside.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet for repeatedly bending devices, a repeatedly bending laminated member, and a repeatedly bending device.

In recent years, bendable displays have been proposed as display bodies (displays) for electronic equipment, which are a type of device. As the bendable display, in addition to a display that is curved only once, a repeatedly bendable display that is repeatedly bent (bent) has been proposed.

In the repeatedly bending display as described above, it is conceivable to bond one bendable member (flexible member) constituting the bendable display and another bendable member with the adhesive layer of the adhesive sheet. be done. However, when a conventional pressure-sensitive adhesive sheet is used for repeatedly bending displays, there arises a problem that peeling occurs at the interface between the pressure-sensitive adhesive layer and the adherend at the bending portion.

Patent Document 1 discloses a pressure-sensitive adhesive intended to suppress the occurrence of peeling during repeated bending, but the effect was not necessarily sufficient.

JP 2016-108555 A

The present invention has been made in view of the actual situation as described above. Provided are a pressure-sensitive adhesive sheet that can be suppressed, and a repeatedly bending laminate member and a repeatedly bending device that can suppress the occurrence of peeling at the interface between an adhesive layer and an adherend even when bent for a long time. for the purpose.

In order to achieve the above objects, firstly, the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one flexible member and another flexible member constituting a device that is repeatedly bent. The adhesive layer is formed by laminating a first adhesive layer and a second adhesive layer, and the adhesive strength of the second adhesive layer side at 23 ° C. is equal to the first adhesive layer. Relatively larger than the adhesive strength of the adhesive layer side, the storage elastic modulus G' (-20) of the adhesive as the entire adhesive layer at -20 ° C. is 0.1 MPa or less, and the first adhesive Provided is a pressure-sensitive adhesive sheet characterized by being bent so that the agent layer is on the outside and the second pressure-sensitive adhesive layer is on the inside (Invention 1).

In the above invention (Invention 1), by having the above configuration and physical properties, the laminate obtained by bonding one flexible member and another flexible member with the above adhesive layer is formed as the first adhesive. When placed in a bent state for a long time with the adhesive layer on the outside and the second adhesive layer on the inside, peeling at the interface between the adhesive layer and the adherend at the bent portion is suppressed. , excellent bending resistance can be obtained.

In the above invention (invention 1), the storage elastic modulus G'(-20) at -20°C of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer is 0.040 MPa or more and 0.1 MPa or less. Preferred (Invention 2).

In the above inventions (inventions 1 and 2), the storage elastic modulus G'(-20) at -20°C of the adhesive constituting the second adhesive layer is 0.100 MPa or more and 0.500 MPa or less. is preferable (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that the adhesive strength of the second pressure-sensitive adhesive layer side to the triacetyl cellulose film at 23° C. is 1 N/25 mm or more and 30 N/25 mm or less (Invention 4). .

In the above inventions (Inventions 1 to 4), it is preferable that the adhesive layer as a whole has a gel fraction of 40% or more and 99% or less (Invention 5).

In the above inventions (Inventions 1 to 5), the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are preferably acrylic adhesives (Invention 6 ).

In the above inventions (Inventions 1 to 6), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. (Invention 7).

Secondly, the present invention provides a flexible member and another flexible member that constitute a device that is repeatedly bent, and an adhesive layer that adheres the one flexible member and the other flexible member to each other. and wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (inventions 1 to 7) (invention 8).

Secondly, the present invention provides a repeatedly bending device (invention 9) comprising the bending laminated member (invention 8).

According to the pressure-sensitive adhesive sheet of the present invention, it is possible to suppress the occurrence of peeling at the interface between the pressure-sensitive adhesive layer and the adherend even when repeatedly applied to a bending device and bent for a long time. Further, according to the repeatedly bending laminate member and the repeatedly bending device according to the present invention, it is possible to suppress the occurrence of peeling at the interface between the pressure-sensitive adhesive layer and the adherend even when bent for a long time.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention; FIG. 1 is a cross-sectional view of a repeatedly flexed laminate member according to an embodiment of the present invention; FIG. 1 is a cross-sectional view of a repeat bending device according to one embodiment of the present invention; FIG. It is an explanatory view (side view) explaining a static bending test.

Embodiments of the present invention will be described below.
[Adhesive sheet]
A pressure-sensitive adhesive sheet according to an embodiment of the present invention has a pressure-sensitive adhesive layer for bonding one flexible member and another flexible member that constitute a repeated bending device. A release sheet is laminated on one side or both sides of the agent layer. Repeat bending devices and bending members are described below.

The pressure-sensitive adhesive layer is formed by laminating a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer. When the pressure-sensitive adhesive sheet according to this embodiment is repeatedly applied to a bending device, the pressure-sensitive adhesive sheet is bent so that the first pressure-sensitive adhesive layer is on the outside and the second pressure-sensitive adhesive layer is on the inside. It is preferable that the adhesive strength of the second adhesive layer side of the adhesive sheet according to the present embodiment at 23° C. is relatively greater than the adhesive strength of the first adhesive layer side. In addition, in the pressure-sensitive adhesive sheet according to the present embodiment, the storage elastic modulus G'(-20) of the pressure-sensitive adhesive layer as a whole at -20°C is preferably 0.1 MPa or less. In addition, the method for measuring the storage elastic modulus in the present specification is as shown in the test examples described later.

In the pressure-sensitive adhesive sheet according to the present embodiment, the storage elastic modulus G′ (−20) of the pressure-sensitive adhesive layer as a whole at −20° C. has a low value as described above, so that the strain generated by repeated bending, That is, the stress (which becomes particularly large at low temperatures) can be suppressed to a low level, and the adhesive exhibits the property of being easily bent and following the bending of the adherend. On the other hand, simply lowering the storage modulus tends to reduce the adhesion to the adherend. In particular, when the adhesiveness to the adherend located inside the bend is lowered, the interface between the pressure-sensitive adhesive layer and the adherend is likely to be peeled off. Therefore, in the pressure-sensitive adhesive sheet according to the present embodiment, the pressure-sensitive adhesive layer has a structure in which a first pressure-sensitive adhesive layer positioned on the outer side of the bend and a second pressure-sensitive adhesive layer positioned on the inner side of the bend are laminated to form the second pressure-sensitive adhesive layer. The adhesive strength on the side of the adhesive layer is relatively greater than the adhesive strength on the side of the first adhesive layer. As a result, while the storage elastic modulus G′ (−20) of the entire adhesive layer is low, the adhesion of the adhesive layer (second adhesive layer) on the side that is in contact with the adherend on the side where peeling is likely to occur due to bending power can be increased. As a result, when a laminate obtained by laminating one flexible member and another flexible member with the adhesive layer in the present embodiment is placed in a bent state for a long period of time, the adhesive layer and the cover at the bent portion The occurrence of peeling at the interface with the adherend is suppressed, and excellent flex resistance is obtained. In particular, even when placed in a bent state for a long period of time under low temperature conditions (eg -20°C) or under endurance conditions (eg 80°C/DRY), excellent flex resistance is exhibited.

In order to make the adhesive strength of the second adhesive layer side at 23° C. relatively larger than the adhesive strength of the first adhesive layer side, as an example, the storage elastic modulus G of the entire adhesive layer '(−20) can be maintained at the above value, the storage elastic modulus G'(−20) of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is reduced to the storage of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer It can be achieved by making the elastic modulus higher than G'(-20). In order to make the storage elastic modulus G' (-20) of the adhesive constituting the second adhesive layer higher than the storage elastic modulus G' (-20) of the adhesive constituting the first adhesive layer, As an example, the glass transition temperature (Tg) of the main polymer (especially (meth)acrylic acid ester polymer) of the adhesive constituting the second adhesive layer is set to It can be achieved by making it higher than the glass transition temperature (Tg) of (especially the (meth)acrylic acid ester polymer). However, it is not limited to this.

From the viewpoint of the above-described flex resistance, the storage elastic modulus G'(-20) of the pressure-sensitive adhesive layer as a whole at -20°C is preferably 0.1 MPa or less, and is 0.090 MPa or less. is more preferably 0.085 MPa or less, and more preferably 0.080 MPa or less. In addition, from the viewpoint of cohesive force, the storage elastic modulus G′ (−20) of the adhesive as the entire adhesive layer is preferably 0.040 MPa or more, more preferably 0.050 MPa or more. In particular, it is preferably 0.060 MPa or more, more preferably 0.070 MPa or more.

In order to set the storage elastic modulus G' (-20) of the adhesive as the entire adhesive layer to the above value, the storage elastic modulus G' (-20) of the adhesive constituting the first adhesive layer is It is preferably 0.1 MPa or less, more preferably 0.090 MPa or less, particularly preferably 0.085 MPa or less, further preferably 0.080 MPa or less. In addition, from the viewpoint of cohesive force, the storage elastic modulus G' (-20) of the adhesive constituting the first adhesive layer is preferably 0.040 MPa or more, more preferably 0.050 MPa or more. It is preferably 0.060 MPa or more, more preferably 0.070 MPa or more.

On the other hand, in order to make the adhesive force of the second adhesive layer side at 23° C. relatively larger than the adhesive force of the first adhesive layer side, the adhesive constituting the second adhesive layer The storage modulus G′ (−20) is preferably 0.100 MPa or more, more preferably 0.105 MPa or more, particularly preferably 0.110 MPa or more, and further preferably 0.115 MPa or more. Preferably. In addition, in order to set the storage elastic modulus G'(-20) of the adhesive as the entire adhesive layer to the above value, the storage elastic modulus G'(-20) of the adhesive constituting the second adhesive layer is preferably 0.500 MPa or less, more preferably 0.300 MPa or less, particularly preferably 0.200 MPa or less, further preferably 0.140 MPa or less.

From the viewpoint of the bending resistance described above, the storage elastic modulus G′(25) of the adhesive as the entire adhesive layer at 25° C. is preferably 0.080 MPa or less, more preferably 0.060 MPa or less. It is more preferably 0.040 MPa or less, and more preferably 0.030 MPa or less. Further, from the viewpoint of cohesive force, the storage elastic modulus G′(25) of the adhesive as the entire adhesive layer is preferably 0.010 MPa or more, more preferably 0.014 MPa or more, particularly It is preferably 0.018 MPa or more, more preferably 0.020 MPa or more.

In order to set the storage elastic modulus G'(25) of the adhesive as the whole adhesive layer to the above value, the storage elastic modulus G'(25) of the adhesive constituting the first adhesive layer is set to 0.5. It is preferably 080 MPa or less, more preferably 0.060 MPa or less, particularly preferably 0.040 MPa or less, further preferably 0.025 MPa or less. From the viewpoint of cohesive force, the storage elastic modulus G'(25) of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer is preferably 0.010 MPa or more, more preferably 0.012 MPa or more. , particularly preferably 0.016 MPa or more, more preferably 0.018 MPa or more.

From the viewpoint of exerting the adhesive strength of the second pressure-sensitive adhesive layer, the storage elastic modulus G'(25) of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is preferably 0.200 MPa or less, and 0.200 MPa or less. It is more preferably 100 MPa or less, particularly preferably 0.080 MPa or less, further preferably 0.050 MPa or less. From the viewpoint of cohesion, the storage elastic modulus G'(25) of the adhesive constituting the second adhesive layer is preferably 0.012 MPa or more, more preferably 0.020 MPa or more. , particularly preferably 0.031 MPa or more, more preferably 0.036 MPa or more.

The storage elastic modulus G'(85) of the adhesive as a whole at 85°C is 0.060 MPa or less from the viewpoint of preventing the storage elastic modulus G' at -20°C from becoming too high. , more preferably 0.040 MPa or less, particularly preferably 0.020 MPa or less, and further preferably 0.018 MPa or less. In addition, the storage elastic modulus G′(85) of the pressure-sensitive adhesive layer as a whole is preferably 0.005 MPa or more, more preferably 0.008 MPa or more, and particularly 0.010 MPa or more. is preferable, and more preferably 0.012 MPa or more. Thereby, it becomes excellent in flex resistance under high temperature.

In order to set the storage elastic modulus G'(85) of the adhesive as the whole adhesive layer to the above value, the storage elastic modulus G'(85) of the adhesive constituting the first adhesive layer is set to 0.5. It is preferably 060 MPa or less, more preferably 0.030 MPa or less, particularly preferably 0.018 MPa or less, further preferably 0.012 MPa or less. From the viewpoint of cohesion, the storage elastic modulus G'(85) of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer is preferably 0.002 MPa or more, more preferably 0.004 MPa or more. , particularly preferably 0.006 MPa or more, more preferably 0.008 MPa or more.

From the viewpoint of preventing the low-temperature storage modulus G' of the second pressure-sensitive adhesive layer from becoming too high, the storage modulus G' (85) of the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is set to 0.5. It is preferably 100 MPa or less, more preferably 0.080 MPa or less, particularly preferably 0.040 MPa or less, further preferably 0.030 MPa or less. In addition, from the viewpoint of flex resistance at high temperatures, the storage elastic modulus G'(85) of the adhesive constituting the second adhesive layer is preferably 0.006 MPa or more, and is 0.012 MPa or more. is more preferably 0.019 MPa or more, and more preferably 0.021 MPa or more.

The gel fraction of the adhesive as the entire adhesive layer is preferably 40% or more, more preferably 50% or more, particularly preferably 60% or more, and further preferably 70% or more. Preferably. In addition, the gel fraction of the adhesive as the entire adhesive layer is preferably 99% or less, more preferably 95% or less, particularly preferably 90% or less, further preferably 85%. or less, and most preferably 80% or less. As a result, the pressure-sensitive adhesive as the whole pressure-sensitive adhesive layer easily satisfies the physical properties described above. In addition, the method for measuring the gel fraction in the present specification is as shown in the test examples described later.

FIG. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to this embodiment.
As shown in FIG. 1, the adhesive sheet 1 is sandwiched between two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. and an adhesive layer 11 . In this specification, the release surface of the release sheet refers to the surface of the release sheet that has releasability, and includes both the surface that has been subjected to release treatment and the surface that exhibits releasability without being subjected to release treatment. .

The pressure-sensitive adhesive layer 11 in this embodiment is a laminate of a first pressure-sensitive adhesive layer 111 and a second pressure-sensitive adhesive layer 112 . However, the present invention is not limited to this.

1. Component 1-1. Adhesive layer When the adhesive sheet 1 according to the present embodiment is repeatedly applied to a bending device, it is bent such that the first adhesive layer 111 is on the outside and the second adhesive layer 112 is on the inside. is. The adhesive strength of the adhesive sheet 1 according to the present embodiment at 23° C. on the second adhesive layer 112 side shows a relatively larger value than the adhesive strength on the first adhesive layer 111 side.

The adhesive constituting the first adhesive layer 111 and the adhesive constituting the second adhesive layer 112 are not particularly limited as long as they satisfy the physical properties described above. Any adhesive, polyurethane-based adhesive, rubber-based adhesive, silicone-based adhesive, or the like may be used. The adhesive may be emulsion type, solvent type or non-solvent type, and may be crosslinked or non-crosslinked. Among them, acrylic pressure-sensitive adhesives that easily satisfy the physical properties described above and are excellent in adhesive physical properties, optical properties, etc. are preferable, and solvent-type acrylic pressure-sensitive adhesives are particularly preferable. Further, the acrylic pressure-sensitive adhesive is preferably of a cross-linking type, more preferably of a thermal cross-linking type.

The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 111 and the pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer 112 may be of the same type or different types. A pressure-sensitive adhesive is preferred, a solvent-type acrylic pressure-sensitive adhesive is particularly preferred, and a heat cross-linking type acrylic pressure-sensitive adhesive is more preferred. On the other hand, the adhesive constituting the first adhesive layer 111 and the adhesive constituting the second adhesive layer 112 have a monomer composition of the main polymer ((meth)acrylic acid ester polymer) in the acrylic adhesive. It is preferable to express the difference in physical properties described above by making them different.

Hereinafter, the case where the adhesive constituting the first adhesive layer 111 and the adhesive constituting the second adhesive layer 112 are both acrylic adhesives will be described, but the present invention is not limited thereto. not something.

Specifically, the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 111 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 112 are each an adhesive composition containing a (meth)acrylic acid ester polymer (A). It is preferably an adhesive obtained from a product, and an adhesive composition containing a (meth) acrylic acid ester polymer (A) and a cross-linking agent (B) (hereinafter sometimes referred to as "adhesive composition P" is particularly preferable. With such an adhesive, it is easy to satisfy the physical properties described above, and good adhesive strength is easy to obtain. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. In addition, the concept of "copolymer" is also included in "polymer".

(1) Component of adhesive composition P (1-1) (meth)acrylic acid ester polymer (A)
The (meth)acrylic acid ester polymer (A) comprises a (meth)acrylic acid alkyl ester and a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer) as monomer units constituting the polymer. and is preferably contained.

The (meth)acrylic acid ester polymer (A) can express preferable adhesiveness by containing a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferable. Alkyl groups may be linear or branched, or may have a cyclic structure.

Examples of (meth)acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-(meth)acrylate, Butyl, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylic acid Examples include n-dodecyl, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. In addition, these may be used independently and may be used in combination of 2 or more type.

In the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 111, the glass transition temperature It is preferred to use monomers with fairly low (Tg). Specifically, it is preferable to use a monomer having a glass transition temperature (Tg) of −55° C. or less, more preferably a monomer of −60° C. or less, and particularly a monomer of −65° C. or less. more preferably -70° C. or lower monomers. Monomers having such a low glass transition temperature (Tg) include, for example, 2-ethylhexyl acrylate (Tg: -70°C), ethyl carbitol acrylate (Tg: -67°C), etc. Among them, acrylic acid 2-ethylhexyl is preferred. Although the lower limit of the glass transition temperature (Tg) is not particularly limited, it is about -100°C.

In the adhesive constituting the second adhesive layer 112, the storage elastic modulus G' (-20) of the adhesive as the entire adhesive layer is set to the above value, and the second adhesive layer at 23 ° C. From the viewpoint of making the adhesive strength of the first adhesive layer side relatively larger than the adhesive strength of the first adhesive layer side, among the above monomers, a monomer having a considerably low glass transition temperature (Tg) (hereinafter referred to as "extremely low Tg monomer" ) and a monomer having a relatively low glass transition temperature (Tg) and capable of exhibiting high adhesiveness (hereinafter sometimes referred to as “low Tg monomer”). Very low Tg monomers are as described above as monomers with a fairly low glass transition temperature (Tg). As the low Tg monomer, it is preferable to use a monomer having a glass transition temperature (Tg) of -10 to -65°C, more preferably a monomer of -20 to -60°C, particularly -25 to - It is preferred to use 55°C monomers, more preferably -30 to -55°C monomers. Low Tg monomers include, for example, n-butyl acrylate (Tg: -54°C), methoxytriethylene glycol acrylate (Tg: -57°C), lauryl acrylate (Tg: -27°C), and the like. n-Butyl acid is preferred.

The blending ratio (by mass) of the ultra-low Tg monomer and the low Tg monomer is preferably 90:10 to 10:90, more preferably 80:20 to 20:80, particularly 70:30 to It is preferably 30:70, more preferably 60:40 to 40:60. Thereby, the balance between the storage elastic modulus G' and the adhesive force of the pressure-sensitive adhesive layer to be obtained can be favorably achieved.

The (meth)acrylic acid ester polymer (A) preferably contains 60% by mass or more of a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer. , more preferably 80% by mass or more, particularly preferably 90% by mass or more, and more preferably 96% or more. If the amount of the (meth)acrylic acid alkyl ester is the above amount or more, the storage elastic modulus G' can be easily adjusted to a lower value while imparting a predetermined adhesiveness to the (meth)acrylic acid ester polymer (A). . In addition, it preferably contains 99.9% by mass or less, particularly preferably 99.5% by mass or less, more preferably 99.0% by mass or less of a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms. It is preferable to contain not more than mass %. By setting the (meth)acrylic acid alkyl ester to the above amount or less, a desired amount of other monomer components can be introduced into the (meth)acrylic acid ester polymer (A).

(Meth)acrylic acid ester polymer (A) contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, so that through the reactive functional group derived from the reactive functional group-containing monomer , reacts with a cross-linking agent (B), which will be described later, to form a cross-linked structure (three-dimensional network structure) and obtain a pressure-sensitive adhesive having desired cohesive strength. The adhesive easily satisfies the physical properties (and gel fraction) related to the storage modulus G' described above.

The (meth)acrylic acid ester polymer (A) contains reactive functional group-containing monomers as monomer units constituting the polymer, including monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), carboxyl groups in the molecule, A monomer having a group (carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), and the like are preferable. One of these reactive functional group-containing monomers may be used alone, or two or more thereof may be used in combination.

Among the reactive functional group-containing monomers, hydroxyl group-containing monomers or carboxy group-containing monomers are preferred, and hydroxyl group-containing monomers are particularly preferred. As a result, the physical properties related to the storage elastic modulus G' described above can be easily satisfied.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, (meth) ) hydroxyalkyl (meth)acrylates such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate; Among these, hydroxyalkyl (meth)acrylic acid having a hydroxyalkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of ease of satisfying the physical properties related to the storage elastic modulus G′ described above. Specifically, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like are preferred, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are particularly preferred. be done. These may be used alone or in combination of two or more.

Carboxy group-containing monomers include, for example, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of adhesive strength of the resulting (meth)acrylic acid ester polymer (A). These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) preferably contains 0.1% by mass or more, particularly 0.4% by mass or more, of a reactive functional group-containing monomer as a monomer unit constituting the polymer. It is preferably contained, more preferably 0.8% by mass or more. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 10% by mass or less, and 6% by mass or less, of a reactive functional group-containing monomer as a monomer unit constituting the polymer. is more preferable, particularly preferably 3% by mass or less, more preferably 2% by mass or less, and most preferably 1.4% by mass or less.

When the (meth)acrylic acid ester polymer (A) contains the reactive functional group-containing monomer in the above amount as a monomer unit, the cohesive force of the obtained adhesive is moderate due to the crosslinking reaction with the crosslinking agent (B). The physical properties (and gel fraction) relating to the storage elastic modulus G' described above, especially the storage elastic modulus G' (80) at 80°C, are easily satisfied.

It is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxy group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, the absence of a carboxyl group-containing monomer causes problems with the adhesive to which the adhesive is attached, such as transparent conductive films such as tin-doped indium oxide (ITO), metal films, and the like. Even when a metal mesh or the like is present, it is possible to suppress the problems (corrosion, resistance value change, etc.) caused by acid.

Here, "not containing a carboxyl group-containing monomer" means that it does not substantially contain a carboxyl group-containing monomer. It is allowed to contain a carboxyl group-containing monomer to the extent that corrosion of the metal does not occur. Specifically, the (meth)acrylic acid ester polymer (A) contains, as a monomer unit, a carboxy group-containing monomer of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001% by mass. It is allowed to be contained in an amount of mass % or less.

The (meth)acrylic acid ester polymer (A) may optionally contain other monomers as monomer units constituting the polymer. As other monomers, monomers containing no reactive functional group are preferred so as not to inhibit the above-described effects of the reactive functional group-containing monomer. Examples of such monomers include non-reactive nitrogen atom-containing monomers such as N-acryloylmorpholine and N-vinyl-2-pyrrolidone, and (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate. Examples include alkoxyalkyl acrylates, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

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

The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 600,000 or more, more preferably 800,000 or more, particularly preferably 1,000,000 or more, and further preferably 1,200,000. It is preferable that it is above. In addition, the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 2.5 million or less, more preferably 2 million or less, particularly preferably 1.7 million or less, and further It is preferably 1.4 million or less. When the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is within the above range, the physical properties (and gel fraction) related to the storage elastic modulus G′ described above, especially the storage elastic modulus G′ at 25° C. ( 25) and storage modulus G'(85) at 85°C. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

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

(1-2) Crosslinking agent (B)
The cross-linking agent (B) cross-links the (meth)acrylic acid ester polymer (A) with heating of the adhesive composition P containing the cross-linking agent (B) as a trigger to form a three-dimensional network structure. . As a result, the cohesive strength of the resulting pressure-sensitive adhesive is improved, and the physical properties and gel fraction regarding the storage elastic modulus G' described above are easily satisfied.

The cross-linking agent (B) may be one that reacts with the reactive groups of the (meth)acrylic acid ester polymer (A). Examples include isocyanate cross-linking agents, epoxy cross-linking agents, and amine cross-linking agents. , melamine cross-linking agent, aziridine cross-linking agent, hydrazine cross-linking agent, aldehyde cross-linking agent, oxazoline cross-linking agent, metal alkoxide cross-linking agent, metal chelate cross-linking agent, metal salt cross-linking agent, ammonium salt cross-linking agent, etc. is mentioned. Among the above, it is preferable to use an isocyanate-based cross-linking agent that has excellent reactivity with the reactive functional group-containing monomer. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. , and their biuret, isocyanurate, and adducts which are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate or trimethylolpropane-modified xylylene diisocyanate, is preferable from the viewpoint of reactivity with hydroxyl groups and carboxy groups.

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.01 part by mass, based on 100 parts by mass of the (meth)acrylic acid ester polymer (A). 06 parts by mass or more, and more preferably 0.12 parts by mass or more. The content is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.4 parts by mass or less. is preferred. When the content of the cross-linking agent (B) is within the above range, the physical properties and gel fraction regarding the storage elastic modulus G' described above are easily satisfied. The content of the cross-linking agent in the first pressure-sensitive adhesive layer 111 is preferably higher than the content of the cross-linking agent in the second pressure-sensitive adhesive layer 112 .

(1-3) Various Additives The pressure-sensitive adhesive composition P may optionally contain various additives commonly used in acrylic pressure-sensitive adhesives, such as silane coupling agents, ultraviolet absorbers, antistatic agents, and tackifiers. Agents, antioxidants, light stabilizers, softeners, fillers, refractive index modifiers and the like can be added. It should be noted that a polymerization solvent and a dilution solvent, which will be described later, are not included in the additives constituting the adhesive composition P.

The adhesive composition P preferably contains the above silane coupling agent. As a result, the resulting pressure-sensitive adhesive layer has improved adhesion to the flexible member, which is the adherend, and has a more favorable adhesive strength.

As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the (meth)acrylic acid ester polymer (A), and having optical transparency. preferable.

Examples of such silane coupling agents include silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as sidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyl Mercapto group-containing silicon compounds such as dimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl Amino group-containing silicon compounds such as dimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of these, methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltriethoxysilane Examples include condensates with alkyl group-containing silicon compounds such as methoxysilane. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the silane coupling agent in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.05 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is preferably at least 0.1 part by mass, more preferably at least 0.1 part by mass. Also, the content is preferably 1 part by mass or less, particularly preferably 0.5 parts by mass or less, and further preferably 0.3 parts by mass or less. When the content of the silane coupling agent is within the above range, the pressure-sensitive adhesive layer to be obtained has improved adhesion to the flexible member, which is the adherend, and has greater adhesive strength.

(2) Production of adhesive composition P The adhesive composition P is produced by producing a (meth)acrylic acid ester polymer (A), and the obtained (meth)acrylic acid ester polymer (A) and a cross-linking agent. It can be produced by mixing (B) and optionally adding an additive.

The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. Polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, optionally using a polymerization initiator. By polymerizing the (meth)acrylic acid ester polymer (A) by a solution polymerization method, it becomes easy to increase the molecular weight of the resulting polymer and adjust the molecular weight distribution, and furthermore, the production of low molecular weight products is reduced. becomes possible. Therefore, even when the gel fraction is relatively small and the degree of cross-linking is moderated, the pressure-sensitive adhesive is less likely to be biased due to repeated bending, and a pressure-sensitive adhesive with excellent bending resistance can be easily obtained. However, the present invention is not limited to this, and may be polymerized without a solvent.

Polymerization solvents used in the solution polymerization method include, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like, and two or more of them may be used in combination.

Examples of polymerization initiators include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane 1-carbonitrile), 2 ,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate) , 4,4′-azobis(4-cyanovaleric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), 2,2′-azobis[2-(2-imidazolin-2-yl) propane] and the like.

Examples of organic peroxides include benzoyl peroxide, t-butylperbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxy dicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide and the like.

The weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

After the (meth)acrylic acid ester polymer (A) is obtained, the solution of the (meth)acrylic acid ester polymer (A) is added with the cross-linking agent (B) and, if desired, the additive and the diluent solvent, and sufficiently By mixing, the adhesive composition P (coating solution) diluted with a solvent is obtained.

In any of the above components, if a solid one is used, or if precipitation occurs when mixed with other components in an undiluted state, the component is added alone in advance to a dilution solvent. It may be dissolved or diluted prior to mixing with other ingredients.

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

The concentration/viscosity of the coating solution thus prepared is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected according to the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 60% by mass. When obtaining the coating solution, the addition of a diluent solvent or the like is not a necessary condition, and the diluent solvent may not be added as long as the viscosity of the adhesive composition P allows coating. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) is used as the diluting solvent.

(3) Production of Adhesive The adhesive constituting the first adhesive layer 111 and the adhesive constituting the second adhesive layer 112 in the present embodiment are obtained by cross-linking the adhesive composition P, respectively. is preferably Crosslinking of the adhesive composition P can usually be performed by heat treatment. This heat treatment can also serve as a drying treatment for volatilizing the diluent solvent and the like from the coating film of the adhesive composition P applied to a desired object.

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

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (eg, 23° C., 50% RH). If the curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, the adhesive is formed after the heat treatment is completed.

By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is sufficiently crosslinked via the crosslinking agent (B) to form a crosslinked structure, thereby obtaining the pressure-sensitive adhesive.

Here, an example of a design guideline for separately producing the adhesive that forms the first adhesive layer 111 and the adhesive that forms the second adhesive layer 112 will be described. The adhesive constituting the first adhesive layer 111 can crosslink the (meth)acrylic ester polymer (A) with a fairly low glass transition temperature (Tg) at a high crosslink density with the crosslinker (B). preferable. On the other hand, the adhesive constituting the second adhesive layer 112 is a (meth)acrylic acid ester polymer (A) whose glass transition temperature (Tg) is not so low, and is slightly crosslinked by a crosslinking agent (B). Density cross-linking is preferred. As a result, in the adhesive constituting the first adhesive layer 111, the glass transition temperature (Tg) of the (meth)acrylic acid ester polymer (A) is considerably low, so that the storage elastic modulus G' at low temperature is goes down. In addition, the high crosslink density suppresses a decrease in the storage elastic modulus G' at high temperatures. On the other hand, the pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer 112 has a slightly low cross-linking density, so that the pressure-sensitive adhesive strength is improved.

(4) Thickness of adhesive layer The thickness of the adhesive layer 11 in the adhesive sheet 1 according to the present embodiment (value measured according to JIS K7130) is preferably 1 μm or more as a lower limit, and is preferably 5 μm or more. is more preferable, particularly preferably 10 μm or more, and further preferably 15 μm or more. When the lower limit value of the thickness of the pressure-sensitive adhesive layer 11 is within the above range, the desired adhesive strength is easily exhibited, and the flex resistance is more excellent.

In addition, the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 300 μm or less, more preferably 150 μm or less, and particularly preferably 90 μm or less, so that a thinner repeatedly bending device can be obtained. From the point of view, it is more preferably 40 μm or less. When the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is above, the stress generated in the pressure-sensitive adhesive layer due to repeated bending can be suppressed from becoming too large, and the bending resistance can be improved.

The lower limit of the thickness of the first adhesive layer 111 is preferably 0.5 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more, and further preferably 8 μm or more. is preferred. When the lower limit value of the thickness of the first adhesive layer 111 is above, the storage elastic modulus G′ (−20) of the adhesive as a whole of the adhesive layer easily satisfies the above value.

In addition, the upper limit of the thickness of the first pressure-sensitive adhesive layer 111 is preferably 150 μm or less, more preferably 75 μm or less, and particularly preferably 45 μm or less, to obtain a thinner repeatedly bending device. From the viewpoint of being able to When the upper limit value of the thickness of the first pressure-sensitive adhesive layer 111 is the above, it is possible to suppress excessive increase in the stress generated in the pressure-sensitive adhesive layer due to repeated bending, and to improve the bending resistance. can. Note that the first adhesive layer 111 may be formed as a single layer, or may be formed by laminating a plurality of layers.

The lower limit of the thickness of the second adhesive layer 112 is preferably 0.5 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more, and further preferably 8 μm or more. is preferred. When the lower limit of the thickness of the second pressure-sensitive adhesive layer 112 is above, the adhesive strength of the second pressure-sensitive adhesive layer 112 can be easily adjusted to a desired level.

In addition, the upper limit of the thickness of the second pressure-sensitive adhesive layer 112 is preferably 150 μm or less, more preferably 75 μm or less, and particularly preferably 45 μm or less, to obtain a thinner repeatedly bending device. From the viewpoint of being able to When the upper limit of the thickness of the second pressure-sensitive adhesive layer 112 is the above, it is possible to suppress excessive increase in the stress generated in the pressure-sensitive adhesive layer due to repeated bending, and to improve the bending resistance. can. In addition, the second adhesive layer 112 may be formed as a single layer, or may be formed by laminating a plurality of layers.

The ratio of the thickness of the first adhesive layer 111 to the thickness of the second adhesive layer 112 is preferably 90:10 to 10:90, particularly preferably 80:20 to 20:80. , 70:30 to 30:70, more preferably 60:40 to 40:60. This makes it easier to satisfy the physical properties of the storage elastic modulus G' and adhesive strength described above.

1-2. Release Sheet The release sheets 12a and 12b protect the adhesive layer 11 until the adhesive sheet 1 is used, and are peeled off when the adhesive sheet 1 (adhesive layer 11) is used. In the adhesive sheet 1 according to this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. Crosslinked films of these are also used. Furthermore, a laminated film of these may be used.

The release surfaces of the release sheets 12a and 12b (especially the surfaces in contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

Of the release sheets 12a and 12b, it is preferable that one of the release sheets is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force. In particular, the release sheet 12a in contact with the first pressure-sensitive adhesive layer 111 with relatively low adhesive strength is a light-release type release sheet, and the release sheet 12b in contact with the second pressure-sensitive adhesive layer 112 with relatively high adhesive strength is a heavy-release type. A release sheet is preferred. As a result, the difference in release force between the release sheet 12a and the release sheet 12b can be increased, resulting in excellent handleability. Specifically, when the release sheet 12a on the side to be released first is peeled off from the first adhesive layer 111, the second adhesive layer 112 and the release sheet 12b are peeled off. can be effectively suppressed.

Although the thickness of the release sheets 12a and 12b is not particularly limited, it is usually about 20 to 150 μm.

2. Physical Properties (1) Haze Value The haze value of the pressure-sensitive adhesive layer 11 at 25° C. is preferably 10% or less, more preferably 5% or less, particularly preferably 3% or less, and further preferably 1%. % or less. When the haze value of the pressure-sensitive adhesive layer 11 is in the above range, the adhesive layer 11 has excellent light transmittance and is suitable for repeated bending displays. The lower limit of the haze value is not particularly limited, and is preferably 0% or more, more preferably 0.1% or more. A haze value in this specification is a value measured according to JIS K7136:2000.

(2) Adhesive strength The adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass on the second adhesive layer 112 side at 23° C. is preferably 0.5 N/25 mm or more as a lower limit. It is more preferably 0 N/25 mm or more, particularly preferably 2.0 N/25 mm or more, further preferably 3.0 N/25 mm or more. When the lower limit of the adhesive strength of the adhesive sheet 1 to soda-lime glass is above, the flex resistance becomes more excellent. On the other hand, the upper limit of the adhesive strength is not particularly limited, but reworkability may be required in some cases. From such a viewpoint, the adhesive strength is preferably 20 N/25 mm or less, more preferably 15 N/25 mm or less, and particularly preferably 10 N/25 mm or less. The adhesive strength in this specification basically refers to the adhesive strength measured by the 180 degree peeling method according to JIS Z0237:2009, and the specific test method is as shown in the test examples described later.

In addition, the adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass on the first adhesive layer 111 side at 23° C. is preferably 0.1 N/25 mm or more from the viewpoint of bending resistance. It is more preferably 0.4 N/25 mm or more, particularly preferably 0.8 N/25 mm or more, and even more preferably 1.2 N/25 mm or more. On the other hand, the upper limit is not particularly limited, but from the viewpoint of compatibility with other physical property values, it is preferably 18 N/25 mm or less, more preferably 10 N/25 mm or less, and 5 N/25 mm or less. is particularly preferable, and 2.5 N/25 mm or less is most preferable.

The adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass on the side of the second adhesive layer 112 at 23° C. is higher than the adhesive strength of the adhesive sheet 1 on the side of the first adhesive layer 111 to soda lime glass at 23° C. also shows a large value.

The lower limit of the adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment to the triacetyl cellulose film on the side of the second pressure-sensitive adhesive layer 112 at 23° C. is preferably 1 N/25 mm or more, and is 2 N/25 mm or more. is more preferable, particularly preferably 3 N/25 mm or more, further preferably 5 N/25 mm or more. When the lower limit of the adhesive force of the adhesive sheet 1 to the triacetyl cellulose film is above, the flex resistance becomes more excellent. On the other hand, the upper limit of the adhesive strength is not particularly limited, but reworkability may be required in some cases. From such a viewpoint, the adhesive strength is preferably 30 N/25 mm or less, more preferably 25 N/25 mm or less, and particularly preferably 20 N/25 mm or less.

In addition, the adhesive force of the first adhesive layer 111 side of the adhesive sheet 1 according to the present embodiment to the triacetyl cellulose film at 23° C. is preferably 0.5 N/25 mm or more from the viewpoint of bending resistance. , more preferably 1.0 N/25 mm or more, particularly preferably 1.5 N/25 mm or more, and even more preferably 2.0 N/25 mm or more. On the other hand, the upper limit is not particularly limited, but from the viewpoint of compatibility with other physical property values, it is preferably 27 N/25 mm or less, more preferably 16 N/25 mm or less, and 11 N/25 mm or less. is particularly preferred, and 6 N/25 mm or less is most preferred.

The adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment to the triacetylcellulose film on the second pressure-sensitive adhesive layer 112 side at 23°C is indicates a value greater than the force.

Regardless of whether the soda-lime glass or the triacetylcellulose film is used as the adherend, the adhesive strength on the second adhesive layer 112 side is 1.1 times the adhesive strength on the first adhesive layer 111 side. It is preferably 1.5 times or more, more preferably 1.5 times or more, and particularly preferably 1.8 times or more. The upper limit is not particularly limited, but considering compatibility with other physical properties, it is preferably 10 times or less, more preferably 5 times or less, and particularly preferably 3 times or less.

3. Production of Adhesive Sheet As one production example of the adhesive sheet 1, the case where the adhesive composition P is used will be described. As an example of manufacturing the adhesive sheet 1, a coating solution of the adhesive composition P for forming the first adhesive layer 111 is applied to the release surface of one release sheet 12a, and heat treatment is performed to adhere. The adhesive composition P is thermally crosslinked to form a coating layer to obtain a release sheet 12a with a coating layer. Further, a coating solution of the adhesive composition P for forming the second adhesive layer 112 is applied to the release surface of the other release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P. , a coating layer is formed to obtain a release sheet 12b with a coating layer. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are pasted together so that both coating layers are in contact with each other. Here, a plurality of release sheets with coating layers may be prepared, and the coating layers may be pasted together in a desired number and in a desired lamination order. If a curing period is required, the curing period is set, and if the curing period is not required, the laminated coating layers become the first adhesive layer 111 and the second adhesive layer 112, respectively. . As a result, the pressure-sensitive adhesive sheet 1 having the pressure-sensitive adhesive layer 11 that is a laminate of the first pressure-sensitive adhesive layer 111 and the second pressure-sensitive adhesive layer 112 is obtained. The conditions for heat treatment and curing are as described above.

Note that the coating layer for forming the first adhesive layer 111 and the coating layer for forming the second adhesive layer 112 may each be sandwiched between two release sheets. When the coating layer for forming the agent layer 111 and the coating layer for forming the second pressure-sensitive adhesive layer 112 are laminated, one of the release sheets may be peeled off.

As a method for applying the coating liquid of the adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

[Repeated bending laminated member]
As shown in FIG. 2, the repeatedly bending laminate member 2 according to the present embodiment includes a first bending member 21 (one bending member) and a second bending member 22 (another bending member). , and an adhesive layer 11 positioned therebetween for adhering the first flexible member 21 and the second flexible member 22 to each other.

The pressure-sensitive adhesive layer 11 in the repeatedly bending laminate member 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 described above. The pressure-sensitive adhesive layer 11 is arranged such that when the bending laminate member 2 is repeatedly bent, the first pressure-sensitive adhesive layer 111 is on the outside of the bend and the second pressure-sensitive adhesive layer 112 is on the inside of the bend. Located between the flexing member 21 and the second flexing member 22 .

The repeat bending laminate member 2 is either the repeat bending device itself or a member forming part of the repeat bending device. The repeatedly bending device is preferably, but not limited to, a display capable of repeatedly bending (including bending) (a repeatedly bending display). Examples of such repeatedly bending devices include organic electroluminescence (organic EL) displays, electrophoretic displays (electronic paper), liquid crystal displays using a plastic substrate (film) as a substrate, foldable displays, and the like. may be

The first flexible member 21 and the second flexible member 22 are members capable of repeated bending (including bending), and examples thereof include cover films, gas barrier films, hard coat films, and polarizing films (polarizing plates). , polarizer, retardation film (retardation plate), viewing angle compensation film, brightness enhancement film, contrast enhancement film, diffusion film, transflective film, electrode film, transparent conductive film, metal mesh film, flexible glass, film Sensor (touch sensor film), liquid crystal polymer film, luminescent polymer film, film-like liquid crystal module, organic EL module (organic EL film, organic EL element), electronic paper module (film-like electronic paper), TFT (Thin Film Transistor) substrate etc.

At least one of the first flexible member 21 and the second flexible member 22 may be a triacetylcellulose film or a laminate having a triacetylcellulose film on the adhesive layer 11 side. A triacetyl cellulose film generally has low adhesion to an adhesive layer, but according to the adhesive layer 11 of the present embodiment, even if the triacetyl cellulose film is an adherend, it has excellent flex resistance. is obtained.

The Young's moduli of the first flexible member 21 and the second flexible member 22 are preferably 0.1 to 10 GPa, particularly preferably 0.5 to 7 GPa, and further preferably 1.0 to 1.0. It is preferably 5 GPa. Since the Young's moduli of the first bending member 21 and the second bending member 22 are within such ranges, each bending member can be easily bent repeatedly.

The thickness of each of the first bending member 21 and the second bending member 22 is preferably 10 to 3000 μm, particularly preferably 25 to 1000 μm, further preferably 50 to 500 μm. . Since the thicknesses of the first bending member 21 and the second bending member 22 are within such ranges, each bending member can be easily bent repeatedly.

In order to manufacture the repeatedly bending laminated member 2, as an example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 (first adhesive layer 111 or second adhesive layer 111) of the adhesive sheet 1 is removed. The pressure-sensitive adhesive layer 112 ) of is adhered to one surface of the first flexible member 21 .

After that, the other release sheet 12b is peeled from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 (second adhesive layer 112 or first adhesive layer 111) of the adhesive sheet 1 and the first adhesive layer 111 are separated. 2 and the flexible member 22 of No. 2 are pasted together to obtain the repeatedly bent laminated member 2 . As another example, the lamination order of the first flexible member 21 and the second flexible member 22 may be changed.

[Repeated bending device]
The repeatedly bending device according to the present embodiment includes the repeatedly bending laminated member 2 described above, and may consist of only the repeatedly bending laminated member 2, or may consist of one or a plurality of repeatedly bending laminated members 2 and another device. and a flexible member. When laminating one repeatedly bending laminated member 2 and another repeatedly bending laminated member 2, or when laminating the repeatedly bending laminated member 2 and another flexible member, the adhesive layer 11 of the adhesive sheet 1 described above is It is preferable to laminate the film through the film.

In the repeatedly bending device according to the present embodiment, since the adhesive layer is made of the above-described adhesive, the adhesive layer and the adherend at the bending portion can be easily bent even when repeatedly bent or when left in a bent state for a long period of time. It is difficult for peeling to occur at the interface with.

An example repetitive bending device according to this embodiment is shown in FIG. The repeated bending device according to the present invention is not limited to the repeated bending device.

As shown in FIG. 3, the repeatedly bending device 3 according to the present embodiment includes, in order from the top, a cover film 31, a first adhesive layer 32, a polarizing film 33, and a second adhesive layer 34. , a touch sensor film 35, a third adhesive layer 36, an organic EL element 37, a fourth adhesive layer 38, and a TFT substrate 39 are laminated. The cover film 31, the polarizing film 33, the touch sensor film 35, the organic EL element 37, and the TFT substrate 39 described above correspond to flexible members. The repeatedly bending device 3 according to the present embodiment may be bent with the cover film 31 side inside, or may be bent with the cover film 31 side outside.

At least one of the first pressure-sensitive adhesive layer 32, the second pressure-sensitive adhesive layer 34, the third pressure-sensitive adhesive layer 36, and the fourth pressure-sensitive adhesive layer 38 is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet 1 described above. It is the agent layer 11 . Any two or more layers of the first adhesive layer 32, the second adhesive layer 34, the third adhesive layer 36, and the fourth adhesive layer 38 are the adhesive of the adhesive sheet 1 described above. It is preferably the layer 11 , and most preferably all the adhesive layers 32 , 34 , 36 , 38 are the adhesive layers 11 of the adhesive sheet 1 . When the adhesive layer 11 is used, it is arranged so that the first adhesive layer 111 is positioned on the outer side of the bending direction of the repeatedly bending device 3 and the second adhesive layer 112 is positioned on the inner side.

Here, for example, when a triacetylcellulose film is laminated on one side or both sides of the polarizing film 33, the first pressure-sensitive adhesive layer 32 and/or the second pressure-sensitive adhesive layer contacting the triacetylcellulose film 34 is preferably the adhesive layer 11 of the adhesive sheet 1 described above.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, or a desired flexible member may be laminated instead of the release sheets 12a and/or 12b.

EXAMPLES The present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
1. Preparation of (meth)acrylic acid ester polymer (A) (1) Preparation of (meth)acrylic acid ester polymer (A1) for first pressure-sensitive adhesive layer 99 parts by weight of 2-ethylhexyl acrylate and 4-acrylic acid A (meth)acrylate polymer (A1) was prepared by copolymerizing 1 part by mass of hydroxybutyl by a solution polymerization method. When the molecular weight of this (meth)acrylic acid ester polymer (A1) was measured by the method described later, the weight average molecular weight (Mw) was 1,200,000.

(2) Preparation of (meth)acrylate polymer (A2) for second pressure-sensitive adhesive layer 49 parts by weight of n-butyl acrylate, 50 parts by weight of 2-ethylhexyl acrylate, and 1 part of 4-hydroxybutyl acrylate Parts by mass were copolymerized by a solution polymerization method to prepare a (meth)acrylic acid ester polymer (A2). When the molecular weight of this (meth)acrylic acid ester polymer (A2) was measured by the method described later, the weight average molecular weight (Mw) was 1,200,000.

2. Preparation of adhesive composition (1) Preparation of adhesive composition for first adhesive layer 100 parts by mass (solid content 0.25 parts by mass of trimethylolpropane-modified xylylene diisocyanate (XDI; manufactured by Soken Chemical Co., Ltd., product name “TD-75”) as a cross-linking agent (B), and a silane coupling agent and 0.20 parts by mass of 3-glycidoxypropyltrimethoxysilane, stirred sufficiently, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition for the first adhesive layer. rice field.

(2) Preparation of the adhesive composition for the second adhesive layer 100 parts by mass of the (meth)acrylic acid ester polymer (A2) obtained in the above step 1 (2), and as a cross-linking agent (B) 0.14 parts by mass of trimethylolpropane-modified xylylene diisocyanate (XDI; product name “TD-75” manufactured by Soken Chemical Co., Ltd.) and 0.20 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition for the second adhesive layer.

3. Production of pressure-sensitive adhesive sheet (1) Formation of coating layer for first pressure-sensitive adhesive layer The coating solution of the pressure-sensitive adhesive composition for the first pressure-sensitive adhesive layer obtained in the above step 2 (1) was coated on one side of a polyethylene terephthalate film. was applied with a knife coater to the release-treated surface of a light-release type release sheet (manufactured by Lintec, product name "SP-PET381031") that had been release-treated with a silicone-based release agent. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer.

(2) Formation of a coating layer for the second pressure-sensitive adhesive layer The coating solution of the pressure-sensitive adhesive composition for the second pressure-sensitive adhesive layer obtained in the above step 2 (2) is applied to one side of the polyethylene terephthalate film, followed by silicone-based peeling. It was applied with a knife coater to the release treated surface of a heavy release type release sheet (manufactured by Lintec, product name "SP-PET752150") treated with a release agent. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer.

(3) Production of adhesive sheet The exposed surface of the coating layer obtained in the above step 3(1) and the exposed surface of the coating layer obtained in the step 3(2) are laminated so that they are in contact with each other. A pressure-sensitive adhesive sheet was obtained by curing for 7 days under conditions of 50% RH. That is, an adhesive with a total thickness of 25 μm consisting of a light release release sheet / first adhesive layer (thickness: 12 μm) / second adhesive layer (thickness: 13 μm) / heavy release release sheet A sticky sheet was obtained. The thickness of the pressure-sensitive adhesive layer is a value measured in accordance with JIS K7130 using a constant pressure thickness measuring instrument (manufactured by Teclock, product name "PG-02").

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth)acrylic acid ester polymer (A) is 100 parts by mass (solid content conversion value). Details of abbreviations and the like in Table 1 are as follows.
[(Meth) acrylic ester polymer (A)]
2EHA: 2-ethylhexyl acrylate 4HBA: 4-hydroxybutyl acrylate BA: n-butyl acrylate

[Comparative Example 1]
A pressure-sensitive adhesive sheet having a single pressure-sensitive adhesive layer (thickness: 25 μm) was prepared in the same manner as in Example 1 using only the coating solution of the pressure-sensitive adhesive composition for the second pressure-sensitive adhesive layer of Example 1. made.

[Comparative Example 2]
100 parts by mass of the (meth)acrylic acid ester polymer (A1) obtained in step 1 (1) of Example 1, and trimethylolpropane-modified xylylene diisocyanate (XDI; manufactured by Soken Chemical Co., Ltd.) as a cross-linking agent (B) , product name “TD-75”) and 0.20 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent are mixed, thoroughly stirred, and diluted with methyl ethyl ketone. By doing so, a coating solution of the adhesive composition was obtained.

A pressure-sensitive adhesive sheet having a single pressure-sensitive adhesive layer (thickness: 25 μm) was prepared in the same manner as in Example 1 using the coating solution of the pressure-sensitive adhesive composition.

[Comparative Example 3]
A pressure-sensitive adhesive sheet having a single pressure-sensitive adhesive layer (thickness: 25 μm) was prepared in the same manner as in Example 1 using only the coating solution of the pressure-sensitive adhesive composition for the first pressure-sensitive adhesive layer of Example 1. made.

The weight average molecular weight (Mw) described above is a polystyrene-equivalent weight average molecular weight measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement).
<Measurement conditions>
・ GPC measurement device: HLC-8020 manufactured by Tosoh Corporation
・ GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
・Measurement solvent: tetrahydrofuran ・Measurement temperature: 40°C

[Test Example 1] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (product name: Tetoron mesh #200), and the mass was weighed with a precision balance, By subtracting the mass of the mesh alone, the mass of the pressure-sensitive adhesive alone was calculated. Let the mass at this time be M1.

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23° C.) for 24 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in an environment of a temperature of 23° C. and a relative humidity of 50%, and further dried in an oven of 80° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. A gel fraction (%) is represented by (M2/M1)×100. Table 2 shows the results.

[Test Example 2] (Measurement of storage elastic modulus G')
A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were laminated to form a laminate having a thickness of 0.2 mm. A 1 cm-square piece was cut out of the obtained laminate of pressure-sensitive adhesive layers, and this was used as a sample.

For the above sample, according to JIS K7244-1, the storage elastic modulus G' was measured under the following conditions by a torsional shear method using a viscoelasticity measuring device (manufactured by Anton paar, product name "MCR301"), The storage modulus G'(-20) at 20°C, the storage modulus G'(25) at 25°C and the storage modulus G'(85) at 85°C (MPa) were obtained. Table 2 shows the results.
Measurement frequency: 1Hz
Nomar Force: 1N
Measurement temperature: -20°C to 100°C

[Test Example 3] (Measurement of haze value)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were attached to glass to prepare measurement samples. After performing background measurement on glass, the haze value (%) was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") according to JIS K7136: 2000 for the measurement sample. It was measured. Table 2 shows the results.

[Test Example 4] (Measurement of adhesive strength)
One of the release sheets was peeled off from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was covered with a polyethylene terephthalate (PET) film having an easy-adhesion layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) to obtain a laminate of release sheet/adhesive layer/PET film. The laminate thus obtained was cut to a width of 25 mm and a length of 110 mm.

On the other hand, the following two types of adherends were prepared.
(1) Soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., product name “soda lime glass”, thickness: 1.1 mm)
(2) Triacetyl cellulose (TAC) film (manufactured by Konica Minolta, product name “KC8UAW”, thickness: 80 μm)

In an environment of 23 ° C. and 50% RH, the release sheet was peeled off from the laminate, and the exposed adhesive layer was attached to each adherend, and was subjected to 0.5 MPa and 50 pressure in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. °C and pressurized for 20 minutes. Then, after leaving it for 24 hours under conditions of 23 ° C. and 50% RH, using a tensile tester (manufactured by Orientec, Tensilon), under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees, the PET film and The adhesive force (N/25 mm) was measured when the laminate with the adhesive layer was peeled off from the adherend. Conditions other than those described here were measured according to JIS Z0237:2009. For the pressure-sensitive adhesive sheet produced in Example 1, both the pressure-sensitive adhesive strength on the first pressure-sensitive adhesive layer side and the pressure-sensitive adhesive strength on the second pressure-sensitive adhesive layer side were measured. Table 2 shows the results.

[Test Example 5] (Evaluation of bending resistance)
In an environment of 23° C. and 50% RH, one of the release sheets was peeled off from the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer in Example 1) was A polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name “PET50TA063”, thickness: 100 μm) was laminated on one side. Next, the other release sheet was peeled off, and the exposed adhesive layer (the second adhesive layer in Example 1) was covered with a triacetyl cellulose (TAC) film (manufactured by Konica Minolta, product name “KC8UAW”, thickness : 80 μm). Then, after pressurizing at 0.5 MPa and 50° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho, it was allowed to stand for 24 hours under conditions of 23° C. and 50% RH. The thus-obtained laminate of PET film/adhesive layer/TAC film was cut to a width of 50 mm and a length of 200 mm, and this was used as a sample.

The obtained sample was placed under an environment of −20° C./50% RH and an environment of 80° C./DRY, as shown in FIG. 4 mm), the film was held for 480 hours while being bent so that the PET film was on the outside and the TAC film was on the inside. After conducting this static bending test, it was visually confirmed whether or not there was peeling at the interface between the pressure-sensitive adhesive layer and the adherend at the bent portion of the test piece. Then, the bending resistance was evaluated based on the following criteria. Table 2 shows the results.
〇: No peeling △: Partial peeling (bubble generation)
×: peeling

As can be seen from Table 2, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the example peeled off at the interface between the pressure-sensitive adhesive layer and the flexible member when the two flexible members were laminated and left in a bent state for a long time. did not occur and had excellent flex resistance. This effect was sufficiently exhibited under the environment of −20° C./50% RH and under the environment of 80° C./DRY.

INDUSTRIAL APPLICABILITY The present invention is suitable for bonding one flexible member (in particular, a triacetylcellulose film or a laminate containing a triacetylcellulose film) and another flexible member constituting a repeatedly bending device.

DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11... Adhesive layer 111... 1st adhesive layer 112... 2nd adhesive layer 12a, 12b... Release sheet 2... Repetitive bending laminated member 21... First flexible member 22... Second adhesive layer Flexible member 3 Repeated bending device 31 Cover film 32 First adhesive layer 33 Polarizing film 34 Second adhesive layer 35 Touch sensor film 36 Third adhesive layer 37 Organic EL element 38... Fourth adhesive layer 39... TFT substrate S... Specimen P... Holding plate

Claims (9)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer for bonding one flexible member and another flexible member constituting a device that is repeatedly bent,
The pressure-sensitive adhesive layer is formed by laminating a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer,
The adhesive strength on the side of the second adhesive layer at 23° C. is relatively greater than the adhesive strength on the side of the first adhesive layer,
The storage elastic modulus G' (-20) of the adhesive as a whole at -20 ° C. is 0.1 MPa or less,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet is bent so that the first pressure-sensitive adhesive layer faces outward and the second pressure-sensitive adhesive layer faces inside. The storage elastic modulus G'(-20) at -20°C of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer is 0.040 MPa or more and 0.1 MPa or less. adhesive sheet. The storage elastic modulus G' (-20) at -20 ° C. of the adhesive constituting the second adhesive layer is 0.100 MPa or more and 0.500 MPa or less. Adhesive sheet described. 4. The adhesive according to any one of claims 1 to 3, wherein the adhesive strength of the second adhesive layer to the triacetyl cellulose film at 23°C is 1 N/25 mm or more and 30 N/25 mm or less. adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer as a whole has a gel fraction of 40% or more and 99% or less. 6. The adhesive according to any one of claims 1 to 5, wherein the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are acrylic adhesives. adhesive sheet. The adhesive sheet comprises two release sheets,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. one flexible member and another flexible member that constitute a device that is repeatedly bent;
A repeatedly bending laminated member comprising an adhesive layer for bonding the one flexible member and the other flexible member to each other,
A repeatedly bending laminate member, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 7. A repeatedly bending device comprising the repeatedly bending laminate member according to claim 8 .

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