Adhesive sheets and flexible devices

Abstract

Provided is an adhesive sheet 1 including a single-layered or multi-layered adhesive agent layer 11, in which at least one of layers constituting the adhesive agent layer 11 comprises an adhesive agent comprising a modified cyclodextrin. When a shear stress of 2000 kPa is applied to the adhesive agent layer 11 for 600 seconds, the creep amount is 5% or more relative to the thickness of the adhesive agent layer 11. When a creep amount obtained when a shear stress of 2000 kPa is applied to the adhesive agent layer 11 for 600 seconds is defined as C1 and a creep amount obtained when subsequently the shear stress applied to the adhesive agent layer 11 is changed to 0 kPa and the creep amount is measured after 20 seconds is defined as C2, the creep change ratio calculated in accordance with formula (I) is 60% or more. A flexible device in which the adhesive sheet 1 is used is less likely to have a curved mark left thereon when the flexible device is released from a curved state.　(I): Creep change ratio (%) = (1-C2 / C1)×100

Description

Technical Field

[0001] The present invention relates to an adhesive sheet and a flexible device using the adhesive sheet.

Background Art

[0002] In recent years, as a display of electronic devices, which is a type of device, a flexible display that can be curved has been proposed. Such a flexible display is expected to have a wide range of applications, for example, for a stationary display such as being curved and installed on a cylindrical pillar, or for a mobile display that can be carried by being bent, folded, or rolled up.

[0003] Examples of types of flexible displays include organic electroluminescence (organic EL) displays, electrophoretic displays (electronic paper), liquid crystal displays using a plastic film as a substrate, and the like.

[0004] In such a flexible display, flexible members constituting the flexible display may be bonded to each other by an adhesive layer of an adhesive sheet.

[0005] Here, a flexible display may not be curved only once, but may be repeatedly curved. Also, in such a flexible display, it may be fixed in a curved state for a long time. When a conventional adhesive sheet is used for a flexible display for such applications, even after being released from the curved state, deformation may occur in the adhesive layer and the flexible display may remain curved, and a curved mark may be left.

[0006] Adhesive sheets for flexible displays are disclosed, for example, in Patent Document 1 and Patent Document 2. In Patent Document 1, an adhesive layer is formed by blending urethane acrylate with an acrylic copolymer and irradiating it with ultraviolet light. In Patent Document 2, an adhesive layer is formed using two types of block copolymers. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2021 / 100635 [Patent Document 2] Special Publication No. 2018-524425 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the adhesive sheets disclosed in Patent Documents 1 and 2 did not necessarily have sufficient resilience from a bent state.

[0009] This invention has been made in view of the above-described circumstances, and aims to provide an adhesive sheet and a flexible device that are less likely to leave bending marks after being released from a bent state. [Means for solving the problem]

[0010] To achieve the above objective, firstly, the present invention provides an adhesive sheet comprising one or more adhesive layers, wherein at least one of the adhesive layers is made of an adhesive containing modified cyclodextrin, the amount of creep when a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds is 5% or more as a ratio to the thickness of the adhesive layer, and when the amount of creep when a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds is C1, and the amount of creep measured 20 seconds after the shear stress applied to the adhesive layer is then 0 kPa is C2, the creep change rate calculated from the following formula (I) is 60% or more (Invention 1). Creep rate (%) = (1 - C2 / C1) × 100 …(I)

[0011] The adhesive layer in the above invention (Invention 1) exhibits excellent relaxation properties against shear stress, and even when deformed by shear stress, it easily returns to its original shape due to its elastic behavior, exhibiting excellent resilience. Therefore, even after a flexible device using the above adhesive layer is bent for a predetermined time and then released from that bent state, the flexible device is less likely to leave bending marks.

[0012] In the above invention (Invention 1), it is preferable that the adhesive containing the modified cyclodextrin is a silicone-based adhesive (Invention 2).

[0013] In the above inventions (Inventions 1 and 2), it is preferable that the adhesive layer consists of multiple layers (Invention 3).

[0014] In the above invention (Invention 3), it is preferable that the thickness of the layer made of the adhesive containing the modified cyclodextrin is 10% or more and 80% or less of the total thickness of the adhesive layer (Invention 4).

[0015] In the above invention (Inventions 3 and 4), it is preferable that the layer made of the adhesive containing the modified cyclodextrin is made of a silicone-based adhesive, and the layer other than the layer made of the adhesive containing the modified cyclodextrin is made of an acrylic-based adhesive (Invention 5).

[0016] In the above invention (Invention 5), it is preferable that the layer made of the acrylic-based adhesive is located on both outermost layers of the adhesive layer (Invention 6).

[0017] In the above invention (Inventions 1 to 6), it is preferably for a flexible device (Invention 7).

[0018] In the above invention (Inventions 1 to 7), it is preferably for a rollable device (Invention 8).

[0019] In the above invention (Inventions 1 to 8), it is preferable that the adhesive sheet includes two release sheets, and the adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 9).

[0020] Second, the present invention provides a flexible device including an adhesive layer in the adhesive sheet (Inventions 1 to 9) (Invention 10).

Advantages of the Invention

[0021] The adhesive sheet and the flexible device according to the present invention are less likely to have bending marks after being released from a curved state.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view of a flexible device according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0023] Embodiments of the present invention will be described below. [Adhesive sheet] An adhesive sheet according to one embodiment of the present invention comprises an adhesive layer consisting of one or more layers, wherein at least one layer constituting the adhesive layer is made of an adhesive containing modified cyclodextrin. When a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds, the amount of creep is preferably 5% or more as a ratio to the thickness of the adhesive layer. Furthermore, when the amount of creep when a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds is C1 (μm), and then the amount of creep measured 20 seconds after applying a shear stress of 0 kPa to the adhesive layer is C2 (μm), the creep change rate calculated from the following formula (I) is preferably 60% or more. Details of the method for measuring the amount of creep are shown in the test examples described later. Creep rate (%) = (1 - C2 / C1) × 100 …(I)

[0024] An adhesive layer that satisfies the above requirements exhibits excellent relaxation properties against shear stress, and even when deformed by shear stress, it easily returns to its original shape due to its elastic behavior, exhibiting excellent resilience. Therefore, even after a flexible device using the above adhesive layer is bent for a predetermined time and then released from that bent state, the flexible device is less likely to leave a bending mark.

[0025] From the viewpoint of relaxation against the above-mentioned shear stress, the amount of creep when a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds is preferably 5% or more, more preferably 6% or more, particularly preferably 7% or more, and even more preferably 8% or more, as a ratio to the thickness of the adhesive layer. On the other hand, from the viewpoint of resilience, the upper limit of the above-mentioned amount of creep is preferably 50% or less, more preferably 40% or less, particularly preferably 30% or less, and even more preferably 20% or less, as a ratio to the thickness of the adhesive layer.

[0026] From the viewpoint of the above-mentioned restorability, the creep change rate is preferably 60% or more, more preferably 61.5% or more, particularly preferably 65% ​​or more, even more preferably 68% or more, and most preferably 72% or more. The upper limit of the creep change rate is 100%, and is not particularly limited, but in practice it is preferably 99% or less, more preferably 95% or less, particularly preferably 90% or less, and from the viewpoint of compatibility with the amount of creep mentioned above, it is even more preferably 80% or less, and most preferably 74% or less.

[0027] The adhesive layer in the adhesive sheet according to this embodiment may consist of one layer or multiple layers, but preferably multiple layers. In the case of one layer, the adhesive layer consists of an adhesive containing modified cyclodextrin.

[0028] In this embodiment, when the adhesive layer consists of multiple layers, the thickness of the layer containing the modified cyclodextrin adhesive is preferably 10-80%, more preferably 12-70%, particularly preferably 15-60%, even more preferably 20-50%, and most preferably 30-45% of the total thickness of the adhesive layer. The lower limit is set as described above, making it easier to satisfy the aforementioned physical properties and to recover from deformation. The upper limit is set as described above, making it easier to exhibit the desired adhesive strength.

[0029] The adhesive containing modified cyclodextrin is preferably a silicone-based adhesive. This allows for a more favorable balance between the ability to follow external forces such as bending and the cohesive force of the film itself, such as resilience.

[0030] In this embodiment, it is preferable that the layer containing the modified cyclodextrin adhesive is made of a silicone-based adhesive, and the layers other than the layer containing the modified cyclodextrin adhesive are made of an acrylic-based adhesive. This makes it easier to satisfy the aforementioned physical properties and to exhibit the desired adhesive strength. Furthermore, normally, an adhesive layer made of a silicone-based adhesive (silicone-based adhesive layer) and an adhesive layer made of an acrylic-based adhesive (acrylic-based adhesive layer) do not adhere well to each other and tend to peel off at their interface. However, by including modified cyclodextrin in the silicone-based adhesive layer, the adhesion between the silicone-based adhesive layer and the acrylic-based adhesive layer is improved, and peeling at their interface is effectively suppressed.

[0031] In this embodiment, if the adhesive layer comprises a silicone-based adhesive layer and an acrylic-based adhesive layer, it is preferable that the acrylic-based adhesive layer is located on both outermost layers of the adhesive layer in this embodiment. This configuration of the adhesive layer increases the adhesion strength between the adhesive layer and the adherend, particularly the components of a flexible device (flexible device member), resulting in a laminate with high durability, especially for the flexible device.

[0032] The following description will refer to the drawings and describe an embodiment in which the adhesive layer is formed by laminating an acrylic adhesive layer, a silicone adhesive layer, and an acrylic adhesive layer in that order, but the present invention is not limited thereto.

[0033] Figure 1 shows a specific configuration of an adhesive sheet as an example according to this embodiment. As shown in Figure 1, the adhesive sheet 1 consists of two release sheets 12a and 12b, and an adhesive layer 11 sandwiched between 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. In this specification, the release surface of a release sheet refers to the surface of the release sheet that has release properties, and includes both surfaces that have undergone a release treatment and surfaces that exhibit release properties even without a release treatment.

[0034] In this embodiment, the adhesive layer 11 is formed by laminating an acrylic adhesive layer 111, a silicone adhesive layer 112, and another acrylic adhesive layer 111 in that order, with the acrylic adhesive layer 111 located on both outermost layers of the adhesive layer 11.

[0035] 1. Components 1-1. Adhesive layer 1-1-1. Acrylic adhesive layer The acrylic adhesive constituting the acrylic adhesive layer 111 in this embodiment is not particularly limited and may be an emulsion type, solvent type, or solvent-free type. It may also be curable by active energy rays, non-curable by active energy rays, crosslinked, non-crosslinked, or a combination of these. Among these, non-curable by active energy rays is preferred in order to obtain good flexibility, and among these, crosslinked types are particularly preferred, and even more preferably, thermally crosslinked types.

[0036] The acrylic adhesive constituting the acrylic adhesive layer 111 is preferably an adhesive obtained by crosslinking an adhesive composition (hereinafter sometimes referred to as "acrylic adhesive composition P") containing a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B). Such an adhesive easily satisfies the aforementioned physical properties and provides good adhesive strength and a predetermined cohesive force, resulting in excellent durability. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "polymer" is also included in "polymer".

[0037] (1) Components of acrylic adhesive composition P (1-1)(meth)acrylic acid ester polymer (A) The (meth)acrylic acid ester polymer (A) preferably contains an alkyl (meth)acrylic acid ester and a monomer having a reactive functional group in its molecule (a monomer containing a reactive functional group) as monomer units constituting the polymer.

[0038] The (meth)acrylic acid ester polymer (A) can exhibit desirable tackiness by containing an alkyl (meth)acrylic acid ester as a monomer unit constituting the polymer. As the alkyl (meth)acrylic acid ester, an alkyl (meth)acrylic acid ester having 1 to 20 carbon atoms in the alkyl group is preferred. The alkyl group may be linear, branched, or have a cyclic structure.

[0039] Examples of alkyl (meth)acrylate esters having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among these, from the viewpoint of easily satisfying the aforementioned physical properties, (meth)acrylate esters having 1 to 12 carbon atoms in the alkyl group are preferred, (meth)acrylate esters having 1 to 8 carbon atoms in the alkyl group are particularly preferred, and (meth)acrylate esters having 1 to 6 carbon atoms in the alkyl group are even more preferred. Specifically, n-butyl (meth)acrylate is preferred, and n-butyl acrylate is particularly preferred. These can be used individually or in combination of two or more types.

[0040] The (meth)acrylic acid ester polymer (A) preferably contains 50 to 99.9% by mass of alkyl (meth)acrylic acid ester having 1 to 20 carbon atoms in the alkyl group as monomer units constituting the polymer, more preferably 65 to 99% by mass, particularly preferably 80 to 98% by mass, and even more preferably 88 to 96% by mass. This makes it easier for the adhesive layer in this embodiment to satisfy the above-mentioned physical properties. Furthermore, suitable tackiness can be imparted to the (meth)acrylic acid ester polymer (A), and other monomer components can be introduced into the (meth)acrylic acid ester polymer (A) in desired amounts.

[0041] The (meth)acrylic acid ester polymer (A) contains a monomer containing a reactive functional group as a monomer unit constituting the polymer. Through the reactive functional group derived from the monomer containing the reactive functional group, it reacts with the crosslinking agent (B) described later, thereby forming a crosslinked structure (three-dimensional network structure) and obtaining an adhesive with the desired cohesive force.

[0042] The (meth)acrylic acid ester polymer (A) contains, as monomer units, preferably, monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), monomers having a carboxyl group in the molecule (carboxyl group-containing monomer), and monomers having an amino group in the molecule (amino group-containing monomer). These reactive functional group-containing monomers may be used individually or in combination of two or more.

[0043] Among the above-mentioned reactive functional group-containing monomers, hydroxyl group-containing monomers or carboxyl group-containing monomers are preferred, and it is also preferable to use hydroxyl group-containing monomers and carboxyl group-containing monomers in combination.

[0044] Examples of hydroxyl group-containing monomers include hydroxyalkyl esters of (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, hydroxyalkyl esters of (meth)acrylates having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred from the viewpoint of how easily they satisfy the aforementioned physical properties. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, with 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate being particularly preferred, and 4-hydroxybutyl acrylate being even more preferred. These may be used alone or in combination of two or more.

[0045] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoint of the adhesiveness of the resulting (meth)acrylic acid ester polymer (A). These may be used individually or in combination of two or more.

[0046] The (meth)acrylic acid ester polymer (A) preferably contains 0.1 to 30% by mass of reactive functional group-containing monomers as monomer units constituting the polymer, in terms of total amount, from the viewpoint of the cohesive force and flexibility of the resulting adhesive, and from the viewpoint of making it easier for the adhesive layer in this embodiment to satisfy the above-mentioned physical properties. More preferably, it contains 0.5 to 20% by mass, more preferably, 1 to 15% by mass, and even more preferably, 3 to 8% by mass.

[0047] When a hydroxyl group-containing monomer and a carboxyl group-containing monomer are used in combination as the reactive functional group-containing monomer, the (meth)acrylic acid ester polymer (A) preferably contains 0.1 to 30% by mass of the hydroxyl group-containing monomer and the carboxyl group-containing monomer, more preferably 0.5 to 20% by mass, particularly preferably 1 to 12% by mass, and even more preferably 2 to 6% by mass, as monomer units constituting the polymer. This results in good cohesive strength and flexibility of the resulting adhesive, and makes it easier for the adhesive layer in this embodiment to satisfy the above-mentioned physical properties.

[0048] The (meth)acrylic acid ester polymer (A) may optionally contain other monomers as monomer units constituting the polymer. Among the other monomers, monomers that do not contain reactive functional groups are preferred in order not to inhibit the aforementioned effects of the reactive functional group-containing monomers. Examples of such monomers include unreactive nitrogen atom-containing monomers such as N-acryloylmorpholine and N-vinyl-2-pyrrolidone, alkoxyalkyl (meth)acrylate esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used individually or in combination of two or more.

[0049] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0050] The weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 500,000 to 3,000,000, more preferably 700,000 to 2,800,000, particularly preferably 900,000 to 2,600,000, and most preferably 1,100,000 to 2,400,000, from the viewpoint of making it easier for the adhesive layer in this embodiment to satisfy the above-mentioned physical properties, more preferably 1,400,000 to 2,200,000, and most preferably 1,700,000 to 2,000,000. The weight-average molecular weight in this specification is the value on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0051] In the acrylic adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more types.

[0052] (1-2) Crosslinking agent (B) The crosslinking agent (B) crosslinks the (meth)acrylic acid ester polymer (A) and forms a three-dimensional network structure when the acrylic adhesive composition P containing the crosslinking agent (B) is heated or otherwise triggered. This results in an adhesive with the desired cohesive force.

[0053] The above-mentioned crosslinking agent (B) can be any agent that reacts with the reactive groups of the (meth)acrylic acid ester polymer (A), and examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. Among the above, if the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, it is preferable to use an isocyanate-based crosslinking agent that has excellent reactivity with the hydroxyl group-containing monomer, and if it contains a carboxyl group-containing monomer, it is preferable to use an epoxy-based crosslinking agent that has excellent reactivity with the carboxyl group-containing monomer. Note that the crosslinking agent (B) can be used alone or in combination of two or more types.

[0054] The isocyanate-based crosslinking 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; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret and isocyanurate forms, as well as adducts which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate or trimethylolpropane-modified xylylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl and carboxyl groups.

[0055] Examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxyl groups.

[0056] The content of the crosslinking agent (B) in the acrylic adhesive composition P is preferably 0.01 to 2 parts by mass, more preferably 0.03 to 1 part by mass, particularly preferably 0.05 to 0.4 parts by mass, even more preferably 0.08 to 0.15 parts by mass, and most preferably 0.1 to 0.14 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer (A). When the content of the crosslinking agent (B) is within the above range, the resulting adhesive is more likely to have the desired cohesive force and flexibility. Furthermore, the adhesive layer in this embodiment is more likely to satisfy the above-mentioned physical properties.

[0057] (1-3) Various additives The acrylic adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, rust inhibitors, fillers, and refractive index modifiers. The polymerization solvent and diluent solvent described later are not included in the additives constituting the acrylic adhesive composition P.

[0058] The acrylic adhesive composition P preferably contains the above-mentioned silane coupling agent. This improves the adhesion between the resulting adhesive layer and the flexible member to be adhered, resulting in a more desirable adhesive strength.

[0059] As a silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in its molecule is preferred, which has good compatibility with the (meth)acrylic acid ester polymer (A) and is light-transmitting.

[0060] Examples of such silane coupling agents include polymerizable unsaturated silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Examples include silicon compounds containing a capto group, amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, or condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used individually or in combination of two or more.

[0061] The content of the silane coupling agent in the acrylic adhesive composition P is preferably 0.01 to 1 part by mass, particularly preferably 0.05 to 0.5 parts by mass, and even more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer (A). When the content of the silane coupling agent is within the above range, the resulting adhesive layer has improved adhesion to the flexible member that is adhered to, and the adhesive strength is greater.

[0062] (1-4) Preparation of acrylic adhesive composition P The acrylic adhesive composition P can be produced by manufacturing a (meth)acrylic acid ester polymer (A), mixing the obtained (meth)acrylic acid ester polymer (A) with a crosslinking agent (B), and optionally adding an additive.

[0063] (Meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. Polymerization of (meth)acrylic acid ester polymer (A) is preferably carried out by solution polymerization using a polymerization initiator if desired. Polymerizing (meth)acrylic acid ester polymer (A) by solution polymerization makes it easier to increase the molecular weight of the resulting polymer and adjust the molecular weight distribution, and further reduces the generation of low molecular weight products. This makes it easier for the adhesion to the flexible member to be bonded to to satisfy the desired physical properties. However, the present invention is not limited thereto, and polymerization may also be carried out without solvents.

[0064] Examples of polymerization solvents used in solution polymerization include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more types may be used in combination.

[0065] Examples of polymerization initiators include azo compounds and organic peroxides, and two or more may be used in combination. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonitride), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

[0066] Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

[0067] Furthermore, in the polymerization process described above, the weight-average molecular weight of the resulting polymer can be adjusted by incorporating a chain transfer agent such as 2-mercaptoethanol.

[0068] Once the (meth)acrylic acid ester polymer (A) is obtained, the crosslinking agent (B), and optionally additives and diluent solvents are added to the solution of the (meth)acrylic acid ester polymer (A), and the mixture is thoroughly mixed to obtain a solvent-diluted acrylic adhesive composition P (coating solution).

[0069] Furthermore, if any of the above components are used in solid form, or if precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted in a diluting solvent beforehand before mixing with the other components.

[0070] Examples of the diluent solvents used include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

[0071] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited, as long as they are within the range of coating, and can be appropriately selected depending on the situation. For example, the acrylic adhesive composition P is diluted to a concentration of 10 to 60% by mass. Note that the addition of a diluent is not a necessary condition when obtaining the coating solution; if the acrylic adhesive composition P has a viscosity suitable for coating, a diluent may not be added. In this case, the acrylic adhesive composition P becomes a coating solution in which the polymerization solvent of the (meth)acrylic acid ester polymer (A) is used directly as the diluent.

[0072] (2) Manufacturing of acrylic adhesives The acrylic adhesive constituting the acrylic adhesive layer 111 is preferably formed by crosslinking an acrylic adhesive composition P. Crosslinking of the acrylic adhesive composition P can usually be performed by heat treatment. This heat treatment can also be combined with the drying treatment used to volatilize diluent solvents, etc., from the coating film of the acrylic adhesive composition P applied to the desired object.

[0073] The heating temperature for the heat treatment is preferably 50 to 150°C, and more preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes.

[0074] After heat treatment, a curing period of 1 to 2 weeks at room temperature (e.g., 23°C, 50% RH) may be allowed if necessary. If a curing period is required, the adhesive will be formed after the curing period has elapsed; if a curing period is not required, the adhesive will be formed after the heat treatment is completed.

[0075] Through 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, and an adhesive is obtained. Such an adhesive will have a predetermined cohesive force.

[0076] (3) Thickness of the acrylic adhesive layer The thickness of the acrylic adhesive layer 111 (measured according to JIS K7130) is preferably 1 to 100 μm, more preferably 2 to 60 μm, particularly preferably 3 to 30 μm, even more preferably 4 to 15 μm, and most preferably 5 to 10 μm. By having the thickness of the acrylic adhesive layer 111 within the above range, the aforementioned physical properties are more easily satisfied, and the desired adhesive strength is more easily achieved.

[0077] The total thickness of the multiple acrylic adhesive layers 111 is preferably 2 to 200 μm, more preferably 4 to 120 μm, particularly preferably 6 to 60 μm, even more preferably 8 to 30 μm, and most preferably 10 to 20 μm, with 12 to 16 μm being the most preferred. Having the total thickness of the acrylic adhesive layers 111 within the above range makes it easier to satisfy the aforementioned physical properties.

[0078] (4) Physical properties of the acrylic adhesive layer (4-1) Adhesive strength The adhesive strength of the acrylic adhesive layer 111 to the soda-lime glass is preferably 0.1 N / 25 mm or more, more preferably 0.5 N / 25 mm or more, particularly preferably 1 N / 25 mm or more, and even more preferably 1.5 N / 25 mm or more. This ensures that when a flexible device to which a flexible member is bonded with the adhesive layer 11 is bent for a predetermined time, and even after being released from that bent state, the adhesion between the adhesive layer 11 and the flexible member is maintained. On the other hand, there is no particular limit to the upper limit of the adhesive strength, however reworkability may be required. From this viewpoint, the adhesive strength is preferably 50 N / 25 mm or less, more preferably 30 N / 25 mm or less, particularly preferably 20 N / 25 mm or less, even more preferably 10 N / 25 mm or less, and most preferably 4 N / 25 mm or less. In this specification, adhesive strength basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2009, and the specific test method is as shown in the test examples described later.

[0079] (4-2) Haze value The haze value of the acrylic adhesive layer 111 is preferably 2% or less, more preferably 1% or less, particularly preferably 0.5% or less, even more preferably 0.3% or less, most preferably 0.1% or less, and most preferably less than 0.1%. The above haze value of the acrylic adhesive layer 111 results in excellent light transmittance, making it suitable for flexible displays. The lower limit of the above haze value is not particularly limited and may be 0% or higher. The haze values ​​in this specification are measured in accordance with JIS K7136:2000.

[0080] (4-3) Total light transmittance The total light transmittance of the acrylic adhesive layer 111 is preferably 90% or higher, more preferably 92% or higher, particularly preferably 95% or higher, and even more preferably 98% or higher. The above-mentioned total light transmittance of the acrylic adhesive layer 111 results in excellent light transmittance, making it suitable for flexible displays. The upper limit of the above total light transmittance is not particularly limited and may be 100%. The total light transmittance in this specification is a value measured in accordance with JIS K7361-1:1997.

[0081] 1-1-2. Silicone-based adhesive layer In this embodiment, the silicone adhesive constituting the silicone adhesive layer 112 preferably contains a silicone adhesive main component and modified cyclodextrin.

[0082] (1) Components of silicone adhesive (1-1) Silicone-based adhesive main agent The silicone adhesive main component in this embodiment may be a condensation-type silicone adhesive or an addition-reaction type silicone adhesive, but an addition-reaction type silicone adhesive is preferred from the viewpoint of compatibility with modified cyclodextrin and processability.

[0083] The addition-reaction type silicone adhesive preferably contains an addition-reaction type silicone resin obtained from a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule, and a silicone resin.

[0084] Examples of alkenyl groups contained in the first polydimethylsiloxane include monovalent hydrocarbon groups such as vinyl group, allyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, and octenyl group, with vinyl group being particularly preferred.

[0085] The content of alkenyl groups in the first polydimethylsiloxane (the ratio of the number of alkenyl groups to the number of methyl groups bonded to silicon atoms) is preferably 0.005 to 0.1 mol%, and particularly preferably 0.01 to 0.05 mol%. The alkenyl groups are preferably located at both ends of the molecular chain, and may also be located in the side chain. When one molecule of the first polydimethylsiloxane contains at least two alkenyl groups, and the content of alkenyl groups is within the above range, a crosslinked structure with high crosslink density is formed, making it easier to satisfy the aforementioned physical properties.

[0086] The degree of polymerization (number of siloxane bonds) of the first polydimethylsiloxane is preferably 200 to 5,000, and particularly preferably 500 to 3,000. The hydrosilyl group content in the second polydimethylsiloxane is preferably 2 to 300 per molecule, and particularly preferably 4 to 200. The degree of polymerization of the second polydimethylsiloxane is preferably 50 to 2,000, and particularly preferably 100 to 1,500. Furthermore, the blending ratio of the second polydimethylsiloxane to 100 parts by mass of the first polydimethylsiloxane is preferably 0.01 to 20 parts by mass, and particularly preferably 0.1 to 10 parts by mass. By keeping the content of each functional group and the blending ratio of the second polydimethylsiloxane to the first polydimethylsiloxane within the above ranges, the addition reaction between the first polydimethylsiloxane and the second polydimethylsiloxane proceeds smoothly.

[0087] Furthermore, it is preferable that the first polydimethylsiloxane does not have a hydrosilyl group, and it is preferable that the second polydimethylsiloxane does not have an alkenyl group.

[0088] Examples of silicone resins include monofunctional siloxane units [(CH3)3SiO 1 / 2 The M unit is [SiO], and the tetrafunctional siloxane unit is [SiO]. 4 / 2MQ resin, which is composed of Q units, can be used. The molar ratio of M units to Q units is preferably 0.6 to 1.7. This silicone resin has the role of imparting tackiness to the silicone adhesive.

[0089] The amount of silicone resin blended with 100 parts by mass of addition-reaction type silicone resin is preferably 1 to 200 parts by mass, more preferably 5 to 120 parts by mass, particularly preferably 10 to 80 parts by mass, and even more preferably 20 to 40 parts by mass. This results in a silicone film with excellent flexibility and cohesiveness.

[0090] The above-mentioned addition-reaction type silicone adhesive preferably contains a catalyst. The catalyst is not particularly limited as long as it can cure the addition-reaction type silicone resin (addition reaction between the first polydimethylsiloxane and the second polydimethylsiloxane), but platinum group metal compounds are particularly preferred. Examples of platinum group metal compounds include particulate platinum, particulate platinum adsorbed on a carbon powder support, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, and rhodium. By including such a catalyst, the curing reaction of the addition-reaction type silicone resin can be carried out more efficiently.

[0091] The amount of catalyst blended with 100 parts by mass of the above-mentioned addition-reaction type silicone resin is preferably 0.01 to 3 parts by mass of platinum, particularly preferably 0.05 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass. This enables stable production in the process described later.

[0092] The above-mentioned addition-reaction type silicone adhesive may also contain various additives other than the above-mentioned components, such as crosslinking agents, reaction inhibitors, colorants, and adhesion enhancers.

[0093] (1-2) Modified cyclodextrins In this embodiment, the modified cyclodextrin is a cyclodextrin in which at least some of the hydroxyl groups are substituted with other functional groups.

[0094] Generally, cyclodextrins with 5 or more glucose units are known. The cyclodextrin that forms the backbone of the modified cyclodextrin in this embodiment may be a cyclodextrin with 5 glucose units, an α-cyclodextrin with 6 glucose units, a β-cyclodextrin with 7 glucose units, or a γ-cyclodextrin with 8 glucose units. Among these, the modified cyclodextrin in this embodiment is preferably at least one of a β-cyclodextrin that has been modified (modified β-cyclodextrin) and a γ-cyclodextrin that has been modified (modified γ-cyclodextrin), from the viewpoint of easily satisfying the aforementioned physical properties.

[0095] In the modified cyclodextrin of this embodiment, examples of functional groups that modify the cyclodextrin (functional groups substituted with hydroxyl groups) include alkoxy groups such as methoxy groups and ethoxy groups, and acyl groups such as acetyl groups. Among these, acyl groups are preferred, and acetyl groups are particularly preferred, from the viewpoint of easily satisfying the aforementioned physical properties.

[0096] In this embodiment, the degree of modification of the modified cyclodextrin is preferably greater than 2.5, particularly preferably 2.7 or higher, and even more preferably 2.8 or higher. On the other hand, the upper limit of the degree of modification is not particularly limited, but may be 3.0 or less, particularly 2.99 or less, and even more preferably 2.98 or less. In this specification, the degree of modification of the modified cyclodextrin refers to the number of hydroxyl groups substituted by other functional groups per glucose constituent unit. Therefore, if all three hydroxyl groups in one glucose constituent unit are substituted, the degree of modification is 3.0.

[0097] In the silicone-based adhesive according to this embodiment, one modified cyclodextrin may be used alone, or two or more may be used in combination.

[0098] The content of modified cyclodextrin in the silicone adhesive according to this embodiment is preferably 0.1 to 30% by mass, more preferably 0.3 to 20% by mass, particularly preferably 0.5 to 15% by mass, and even more preferably 1 to 10% by mass. By having the content of modified cyclodextrin within the above range, good adhesion with the acrylic adhesive layer 111 is achieved, and the aforementioned physical properties are more easily satisfied.

[0099] (2) Manufacturing of silicone-based adhesives Silicone-based adhesives can be manufactured by applying a silicone-based adhesive coating solution, which is a mixture of the components of the aforementioned silicone-based adhesive main agent, modified cyclodextrin, and optionally a diluent, and then curing it.

[0100] When the silicone-based adhesive is an addition-reaction type silicone adhesive, it is preferable to heat-cur the applied adhesive solution. In this case, the heating temperature is preferably 80 to 180°C, and the heating time is preferably about 30 to 240 seconds.

[0101] (3) Thickness of the silicone adhesive layer The thickness of the silicone adhesive layer 112 (measured according to JIS K7130) is preferably 0.5 to 100 μm, more preferably 1 to 60 μm, particularly preferably 3 to 30 μm, even more preferably 4 to 25 μm, and most preferably 5 to 20 μm, with the most preferred being 8 to 15 μm. By having the thickness of each of the silicone adhesive layers 112 within the above range, the aforementioned physical properties are more easily satisfied, and good adhesion with the acrylic adhesive layer 111 is ensured.

[0102] (4) Physical properties of the silicone adhesive layer (4-1) Adhesive strength The adhesive strength of the silicone adhesive layer 112 to the soda-lime glass is preferably 0.001 N / 25 mm or more, more preferably 0.01 N / 25 mm or more, particularly preferably 0.03 N / 25 mm or more, even more preferably 0.05 N / 25 mm or more, and most preferably 0.1 N / 25 mm or more. This ensures that when a flexible device to which components are bonded by the adhesive layer 11 is bent for a predetermined time, and even after being released from the bent state, the adhesion between the silicone adhesive layer 112 and the acrylic adhesive layer 111 is maintained. On the other hand, there is no particular limit to the upper limit of the adhesive strength, but it is usually preferably 10 N / 25 mm or less, more preferably 5 N / 25 mm or less, particularly preferably 1 N / 25 mm or less, even more preferably 0.5 N / 25 mm or less, and most preferably 0.16 N / 25 mm or less.

[0103] (4-2) Haze value The haze value of the silicone adhesive layer 112 is preferably 2% or less, more preferably 1% or less, particularly preferably 0.5% or less, even more preferably 0.3% or less, and most preferably 0.2% or less. The above haze value of the silicone adhesive layer 112 results in excellent light transmittance, making it suitable for flexible displays. The lower limit of the above haze value is not particularly limited and may be 0% or higher.

[0104] (4-3) Total light transmittance The total light transmittance of the silicone adhesive layer 112 is preferably 90% or more, more preferably 92% or more, particularly preferably 95% or more, and even more preferably 98% or more. The above-mentioned total light transmittance of the silicone adhesive layer 112 results in excellent light transmittance, making it suitable for flexible displays. The upper limit of the above-mentioned total light transmittance is not particularly limited and may be 100%.

[0105] 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.

[0106] It is preferable to use plastic films as the release sheets 12a and 12b. Examples of plastic films that can be used include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin film. These plastic films may be single layers or multilayer films of two or more layers of the same or different types. Furthermore, these plastic films may be uniaxially oriented or biaxially oriented. Among these, polyester film is preferred, and polyethylene terephthalate film is particularly preferred. Polyethylene terephthalate film is less likely to generate dust during processing and use, for example, it can effectively prevent coating defects caused by dust, and is also relatively inexpensive, thus contributing to cost reduction in production.

[0107] It is preferable that the release surfaces of the above-mentioned release sheets 12a and 12b (especially the surfaces in contact with the adhesive layer 11) are subjected to a release treatment. Examples of release agents used in the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax-based release agents. It is preferable that one of the release sheets 12a and 12b be a heavy-release type release sheet with a high release force, and the other release sheet be a light-release type release sheet with a low release force.

[0108] There are no particular restrictions on the thickness of the release sheets 12a and 12b, but they are usually around 20 to 150 μm.

[0109] 2. Manufacturing of adhesive sheets As one example of manufacturing the adhesive sheet 1, a coating solution of an acrylic adhesive composition P is applied to the release surface of one release sheet 12a, and a heat treatment is performed to thermally crosslink the acrylic adhesive composition P, forming a coating layer to obtain a release sheet 12a with an acrylic adhesive coating layer. Similarly, a coating solution of the acrylic adhesive composition P is applied to the release surface of the other release sheet 12b, and a heat treatment is performed to thermally crosslink the acrylic adhesive composition P, forming a coating layer to obtain a release sheet 12b with an acrylic adhesive coating layer. Separately, the aforementioned silicone adhesive coating solution is applied to the release surface of a release sheet (not shown), and then dried and cured to form a silicone adhesive layer 112, thereby obtaining a release sheet with a silicone adhesive layer. Note that the release sheet for the silicone adhesive layer may be a plastic film that has not been treated for release, or it may be a plastic film that has been treated for release. Unless there is a particular problem, a plastic film that has been treated for release may be used.

[0110] Next, the silicone adhesive layer 112 of the release sheet with the silicone adhesive layer is laminated onto the acrylic adhesive layer of the release sheet 12a (or release sheet 12b) with the acrylic adhesive layer, and the release sheet is peeled off. Then, the exposed silicone adhesive layer 112 is laminated onto the acrylic adhesive layer of the release sheet 12b (or release sheet 12a) with the acrylic adhesive layer. If a curing period is required, a curing period is allowed; if a curing period is not required, the acrylic adhesive layers become the acrylic adhesive layer 111. This results in an adhesive sheet 1 consisting of release sheet 12a / acrylic adhesive layer 111 / silicone adhesive layer 112 / acrylic adhesive layer 111 / release sheet 12b. The conditions for the heat treatment, curing, and curing are as described above.

[0111] For example, methods such as bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating can be used to apply the acrylic adhesive composition P and the silicone adhesive coating.

[0112] Flexible devices A flexible device according to one embodiment of the present invention is equipped with an adhesive layer 11 in the adhesive sheet 1 described above, and has a configuration in which desired flexible members are bonded together by the adhesive layer 11.

[0113] Examples of flexible devices according to this embodiment include flexible displays such as organic electroluminescent (OLED) displays, electrophoretic displays (electronic paper), liquid crystal displays, micro-LED displays, and quantum dot displays, as well as flexible printed circuit boards and flexible sensors.

[0114] The flexible device according to this embodiment is preferably a rollable device that can be repeatedly rolled up and flattened. When rolling up the flexible device according to this embodiment, the diameter of the flexible device is preferably 0.1 to 10 cm, more preferably 0.5 to 7.5 cm, particularly preferably 0.8 to 6 cm, and even more preferably 1 to 5 cm. Even after being rolled up as described above, the flexible device according to this embodiment is less likely to leave a curvature mark and easily returns to a flat state.

[0115] Figure 2 shows a specific configuration as an example of a flexible device according to this embodiment. As shown in Figure 2, the flexible device 2 is composed of a first flexible member 21, a second flexible member 22, and an adhesive layer 11 located between them that bonds the first flexible member 21 and the second flexible member 22 to each other.

[0116] The adhesive layer 11 in the flexible device 2 described above is the adhesive layer 11 of the adhesive sheet 1 described above. Although not shown in Figure 2, the adhesive layer 11 in this embodiment consists of a three-layer structure in which an acrylic adhesive layer 111, a silicone adhesive layer 112, and an acrylic adhesive layer 111 are laminated in that order.

[0117] The first flexible member 21 and the second flexible member 22 are members that can be repeatedly bent (including rounded), and examples include cover films, barrier films, polarizing films, polarizers, phase difference films, viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transparent reflective films, electrode films, transparent conductive films, metal mesh films, film sensors, liquid crystal polymer films, light-emitting polymer films, film-type liquid crystal modules, organic EL modules (organic EL films), electronic paper modules (film-type electronic paper), and the like.

[0118] Among the above, it is preferable that at least one of the first flexible member 21 and the second flexible member 22 is a display element that can be repeatedly bent, specifically a liquid crystal polymer film, a light-emitting polymer film, a film-type liquid crystal module, an organic EL module (organic EL film), or an electronic paper module (film-type electronic paper).

[0119] The Young's moduli of the first flexible member 21 and the second flexible member 22 are preferably 0.05 to 10 GPa, particularly preferably 0.1 to 8 GPa, and even more preferably 1 to 6 GPa. Having the Young's moduli of the first flexible member 21 and the second flexible member 22 within this range makes it easy to repeatedly bend each flexible member.

[0120] The thickness of the first flexible member 21 and the second flexible member 22 is preferably 5 to 3000 μm, particularly preferably 10 to 1000 μm, and even more preferably 10 to 500 μm. Having the thicknesses of the first flexible member 21 and the second flexible member 22 within this range makes it easy to repeatedly bend each flexible member.

[0121] To manufacture the flexible device 2 described above, one example is to peel off one of the release sheets 12a of the adhesive sheet 1 and adhere the exposed adhesive layer 11 of the adhesive sheet 1 to one side of the first flexible member 21.

[0122] Subsequently, the release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second flexible member 22 to obtain the flexible device 2. Alternatively, as another example, the bonding order of the first flexible member 21 and the second flexible member 22 may be reversed.

[0123] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0124] For example, the adhesive layer 11 does not have to be a three-layer structure, there may be multiple silicone-based adhesive layers 112, and the acrylic-based adhesive layer 111 may be a single layer or have three or more layers. Also, either one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, and a desired component may be laminated in place of the release sheets 12a and / or 12b.

[0125] In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y." [Examples]

[0126] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0127] [Preparation Example 1] 1.8 g of β-cyclodextrin (manufactured by Nacalai Tesque) and 47 mg of p-toluenesulfonic acid monohydrate as a catalyst were added to 8.5 ml of isopropenyl acetate as a solvent, and the mixture was reacted at 70°C for 16 hours. The reaction solution was removed by distillation under reduced pressure, and the resulting solid was washed with a 10% by mass aqueous solution of sodium carbonate. After extraction with chloroform, the mixture was recrystallized with acetone to obtain 2.5 g of acetylated β-cyclodextrin (PAcβCD) as a white solid.

[0128] A portion of the obtained acetylated β-cyclodextrin is dissolved in deuterated chloroform. 1 The analysis was performed using 1H-NMR (JEOL Ltd., product name "Nuclear Magnetic Resonance Spectrometer JNM-LA400 / WB"). The results of the analysis showed that 1 The degree of modification was calculated to be 2.98 based on the integral ratio of the peak derived from the proton attached to the carbon atom at position 1 of the glucose ring at approximately 5.1 ppm in the 1H-NMR chart and the peak derived from the acetyl group at approximately 2.1 ppm.

[0129] [Preparation Example 2] Two g of γ-cyclodextrin (manufactured by Nacalai Tesque) and 47 mg of p-toluenesulfonic acid monohydrate as a catalyst were added to 8.5 ml of isopropenyl acetate as a solvent, and the mixture was reacted at 70°C for 16 hours. The reaction solution was removed by distillation under reduced pressure, and the resulting solid was washed with a 10% by mass aqueous solution of sodium carbonate. After extraction with chloroform, the mixture was recrystallized with acetone to obtain 2.5 g of acetylated γ-cyclodextrin (PAcγCD) as a white solid.

[0130] A portion of the obtained acetylated γ-cyclodextrin is dissolved in deuterated chloroform. 1 The analysis was performed using 1H-NMR (JEOL Ltd., product name "Nuclear Magnetic Resonance Spectrometer JNM-LA400 / WB"). The results of the analysis showed that 1 The degree of modification was calculated to be 2.97 based on the integral ratio of the peak derived from the proton attached to the carbon atom at position 1 of the glucose ring at approximately 5.1 ppm in the 1H-NMR chart and the peak derived from the acetyl group at approximately 2.1 ppm.

[0131] [Manufacturing Example 1] (Manufacturing of Silicone-based Adhesive Sheet I) 1. Preparation of silicone adhesive coating solution 100 parts by mass (based on solid content; the same applies hereafter) of addition-reaction type silicone resin (Shin-Etsu Chemical Co., Ltd., "KS-847H"), 30 parts by mass of silicone resin (Dow-Toray Ltd., "SD-4584"), 2 parts by mass of platinum catalyst (Dow-Toray Ltd., "SRX 212 CATALYST"), 1 part by mass of acetylated γ-cyclodextrin prepared in Preparation Example 2, and methyl ethyl ketone as a diluent were mixed to make a silicone-based adhesive coating solution.

[0132] 2. Preparation of silicone adhesive sheets The silicone-based adhesive coating solution obtained in step 1 above was applied to one side of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100-50S", thickness 50 μm) as a second release sheet using a knife coater. The coated layer was then heat-treated at 120°C for 2 minutes to form silicone-based adhesive layers with thicknesses of 5 μm and 10 μm, respectively.

[0133] Next, the silicone adhesive layer on the second release sheet obtained above was laminated with a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T100-50S", thickness 50 μm) as the first release sheet to produce silicone adhesive sheets having silicone adhesive layers of thickness 5 μm and 10 μm, respectively. Specifically, silicone adhesive sheet I-5 was produced, consisting of a first release sheet / silicone adhesive layer (thickness: 5 μm) / second release sheet, and silicone adhesive sheet I-10 was produced, consisting of a first release sheet / silicone adhesive layer (thickness: 10 μm) / second release sheet. The adhesive layer of silicone adhesive sheet I-5 is referred to as "silicone adhesive layer I-5," and the adhesive layer of silicone adhesive sheet I-10 is referred to as "silicone adhesive layer I-10." The thickness of the adhesive layer was measured in accordance with JIS K7130 using a constant-pressure thickness measuring instrument (TECLOCK Co., Ltd., product name "PG-02").

[0134] [Manufacturing Example 2] (Manufacturing of Silicone-based Adhesive Sheet II) A silicone-based adhesive coating solution was obtained in the same manner as in Production Example 1, except that acetylated β-cyclodextrin prepared in Production Example 1 was used instead of acetylated γ-cyclodextrin. Next, using this silicone-based adhesive coating solution, a silicone-based adhesive sheet II-5 was prepared in the same manner as in Production Example 1, consisting of a first release sheet / silicone-based adhesive layer (thickness: 5 μm) / second release sheet. The adhesive layer of the above silicone-based adhesive sheet II-5 is referred to as the "silicone-based adhesive layer II-5".

[0135] [Manufacturing Example 3] (Manufacturing of Silicone-based Adhesive Sheet III) A silicone-based adhesive coating solution was obtained in the same manner as in Production Example 1, except that acetylated γ-cyclodextrin was not included. Next, using this silicone-based adhesive coating solution, a silicone-based adhesive sheet III-10 was prepared in the same manner as in Production Example 1, consisting of a first release sheet / silicone-based adhesive layer (thickness: 10 μm) / second release sheet. The adhesive layer of the above silicone-based adhesive sheet III-10 is referred to as "silicone-based adhesive layer III-10".

[0136] [Manufacturing Example 4] (Manufacturing of Acrylic Adhesive Sheet IV) 1. Preparation of (meth)acrylic acid ester polymer (A) (Meth)acrylic acid ester polymer (A) was prepared by copolymerizing 95 parts by mass of n-butyl acrylate and 5 parts by mass of 4-hydroxybutyl acrylate by solution polymerization. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later and found to be 1.9 million by weight-average molecular weight (Mw).

[0137] 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in step 1 above, 0.14 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as an isocyanate-based crosslinking agent (B), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0138] 3. Manufacturing of acrylic adhesive sheets The adhesive composition coating solution obtained in step 2 above was applied using a knife coater to the peeled surface of a heavy-peel type release sheet (Lintec Corporation, product name "SP-PET382150"), which had one side of a polyethylene terephthalate film peeled with a silicone-based release agent. The coated layer was then heated at 90°C for 1 minute to form a coating layer.

[0139] Next, the coating layer on the heavy-peel release sheet obtained above and a light-peel release sheet (Lintec Corporation, product name "SP-PET381031"), which was obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent, were laminated so that the peeled surface of the light-peel release sheet was in contact with the coating layer. By curing under conditions of 23°C and 50% RH for 7 days, adhesive sheets with adhesive layers of thickness 5 μm, 10 μm, and 25 μm were produced. Specifically, acrylic adhesive sheet IV-5 consisting of a heavy-peel release sheet / adhesive layer (thickness: 5 μm) / light-peel release sheet, acrylic adhesive sheet IV-10 consisting of a heavy-peel release sheet / adhesive layer (thickness: 10 μm) / light-peel release sheet, and acrylic adhesive sheet IV-25 consisting of a heavy-peel release sheet / adhesive layer (thickness: 25 μm) / light-peel release sheet were produced. The adhesive layer of the acrylic adhesive sheet IV-5 is referred to as "acrylic adhesive layer IV-5," the adhesive layer of the acrylic adhesive sheet IV-10 is referred to as "acrylic adhesive layer IV-10," and the adhesive layer of the acrylic adhesive sheet IV-25 is referred to as "acrylic adhesive layer IV-25."

[0140] [Manufacturing Example 5] (Manufacturing of acrylic adhesive sheet V) 1. Preparation of (meth)acrylic acid ester polymer (A) (Meth)acrylic acid ester polymer (A) was prepared by copolymerizing 90 parts by mass of n-butyl acrylate, 5 parts by mass of 4-hydroxybutyl acrylate, and 5 parts by mass of acrylic acid using a solution polymerization method. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later and found to be a weight-average molecular weight (Mw) of 1.6 million.

[0141] 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in step 1 above, 0.05 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane as an epoxy crosslinking agent (B), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0142] 3. Manufacturing of acrylic adhesive sheets Using the coating solution of the adhesive composition obtained in step 2 above, acrylic adhesive sheets V-5 consisting of a heavy-peel release sheet / adhesive layer (thickness: 5 μm) / light-peel release sheet, acrylic adhesive sheet V-10 consisting of a heavy-peel release sheet / adhesive layer (thickness: 10 μm) / light-peel release sheet, and acrylic adhesive sheet V-25 consisting of a heavy-peel release sheet / adhesive layer (thickness: 25 μm) / light-peel release sheet were prepared in the same manner as in manufacturing example 1. The adhesive layer of acrylic adhesive sheet V-5 is referred to as "acrylic adhesive layer V-5", the adhesive layer of acrylic adhesive sheet V-10 is referred to as "acrylic adhesive layer V-10", and the adhesive layer of acrylic adhesive sheet V-25 is referred to as "acrylic adhesive layer V-25".

[0143] [Manufacturing Example 6] (Manufacturing of acrylic adhesive sheet VI) 1. Preparation of (meth)acrylic acid ester polymer (A) (Meth)acrylic acid ester polymer (A) was prepared by copolymerizing 55 parts by mass of n-butyl acrylate, 40 parts by mass of 2-ethylhexyl acrylate, and 5 parts by mass of 4-hydroxybutyl acrylate by solution polymerization. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later and found to be a weight-average molecular weight (Mw) of 1 million.

[0144] 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in step 1 above, 0.15 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as an isocyanate-based crosslinking agent (B), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0145] 3. Manufacturing of acrylic adhesive sheets Using the coating solution of the adhesive composition obtained in step 2 above, an acrylic adhesive sheet VI-25 consisting of a heavy-peel release sheet / adhesive layer (thickness: 25 μm) / light-peel release sheet was prepared in the same manner as in manufacturing example 1. The adhesive layer of this acrylic adhesive sheet VI-25 is referred to as the "acrylic adhesive layer VI-25".

[0146] [Manufacturing Example 7] (Manufacturing of Acrylic Adhesive Sheet VII) 1. Preparation of (meth)acrylic acid ester polymer (A) (Meth)acrylic acid ester polymer (A) was prepared by copolymerizing 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid using a solution polymerization method. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later and found to be 1.8 million in weight-average molecular weight (Mw).

[0147] 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in step 1 above, 0.08 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane as an epoxy crosslinking agent (B), 15 parts by mass of an active energy ray curable resin (a 10:1 mixture (by mass ratio) of "Aronics M-315" manufactured by Toagosei Co., Ltd. and "OMNIRAD 184" manufactured by IGM resins), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

[0148] 3. Manufacturing of acrylic adhesive sheets The adhesive composition coating solution obtained in step 2 above was applied using a knife coater to the peeled surface of a heavy-peel type release sheet (Lintec Corporation, product name "SP-PET382150"), which had one side of a polyethylene terephthalate film peeled with a silicone-based release agent. The coated layer was then heated at 90°C for 1 minute to form a coating layer.

[0149] Next, the coating layer on the heavy-peel release sheet obtained above and a light-peel release sheet (Lintec Corporation, product name "SP-PET381031"), which had one side of a polyethylene terephthalate film peeled off with a silicone-based release agent, were laminated so that the peeled surface of the light-peel release sheet was in contact with the coating layer. Then, ultraviolet light was irradiated onto the coating layer through the light-peel release sheet under the following conditions to cure the coating layer and form an adhesive layer with a thickness of 25 μm. As a result, an acrylic adhesive sheet VII-25 was produced consisting of a heavy-peel release sheet / adhesive layer (thickness: 25 μm) / light-peel release sheet. The adhesive layer of this acrylic adhesive sheet VII-25 is called the "acrylic adhesive layer VII-25". <Ultraviolet irradiation conditions> • Use of high-pressure mercury lamps ·Illuminance 200mW / cm 2 ,Light intensity 200mJ / cm 2 • The UV irradiance / light intensity meter used is the "UVPF-36" manufactured by iGraphics Co., Ltd.

[0150] Table 2 shows the composition of the (meth)acrylic acid ester polymer (A) in Production Examples 4 to 7 and the amount of each component (parts by mass per 100 parts by mass of (meth)acrylic acid ester polymer (A)). The abbreviations in Table 2 are as follows. [(meth)acrylic acid ester polymer (A)] BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate 4HBA: 4-hydroxybutyl acrylate AA: Acrylic acid [Crosslinking agent (B)] Isocyanate-based crosslinking agent: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Mitsui Chemicals, product name "Takenate D-101E") Epoxy crosslinking agent: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane

[0151] The weight-average molecular weight (Mw) mentioned above is the weight-average molecular weight in polystyrene terms, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> • GPC measuring device: Tosoh Corporation, HLC-8020 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Guard Column HXL-H TSK gel GMHXL (x2) TSK gel G2000HXL • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0152] [Example 1] Using one silicone-based adhesive sheet II-5 obtained in Manufacturing Example 2 and two acrylic-based adhesive sheets IV-10 obtained in Manufacturing Example 4, an adhesive sheet with a three-layer adhesive structure and a simulated flexible device were manufactured.

[0153] Specifically, the light-peel release liner of one acrylic adhesive sheet IV-10 was peeled off, and the first release liner of the silicone adhesive sheet II-5 was peeled off, and the exposed acrylic adhesive layer and the silicone adhesive layer were bonded together. Next, the second release liner was peeled off from the silicone adhesive layer, and the light-peel release liner of the other acrylic adhesive sheet IV-10 was peeled off, and the exposed silicone adhesive layer and the acrylic adhesive layer were bonded together. As a result, an adhesive sheet consisting of a heavy-peel release liner / acrylic adhesive layer IV-10 (10 μm) / silicone adhesive layer II-5 (5 μm) / acrylic adhesive layer IV-10 (10 μm) / heavy-peel release liner was obtained.

[0154] Furthermore, each double-peel release sheet was peeled off from the obtained adhesive sheet, and polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360 100μm", thickness 100μm) was attached to both sides of the exposed adhesive layer. This resulted in obtaining a simulated flexible device consisting of a laminate of PET film (100μm) / acrylic adhesive layer IV-10 (10μm) / silicone adhesive layer II-5 (5μm) / acrylic adhesive layer IV-10 (10μm) / PET film (100μm).

[0155] [Example 2] Using one silicone-based adhesive sheet I-5 obtained in Manufacturing Example 1 and two acrylic-based adhesive sheets IV-10 obtained in Manufacturing Example 4, an adhesive sheet having a three-layer adhesive structure and a simulated flexible device were manufactured in the same manner as in Example 1. Specifically, an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer IV-10 (10 μm) / silicone-based adhesive layer I-5 (5 μm) / acrylic adhesive layer IV-10 (10 μm) / double-peel release sheet was obtained, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer IV-10 (10 μm) / silicone-based adhesive layer I-5 (5 μm) / acrylic adhesive layer IV-10 (10 μm) / PET film (100 μm) was obtained.

[0156] [Example 3] Using one silicone-based adhesive sheet I-10 obtained in Manufacturing Example 1, one acrylic-based adhesive sheet IV-10 obtained in Manufacturing Example 4, and one acrylic-based adhesive sheet IV-5 obtained in Manufacturing Example 4, an adhesive sheet having a three-layer adhesive structure and a simulated flexible device were manufactured in the same manner as in Example 1. Specifically, an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer IV-10 (10 μm) / silicone-based adhesive layer I-10 (10 μm) / acrylic adhesive layer IV-5 (5 μm) / double-peel release sheet was obtained, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer IV-10 (10 μm) / silicone-based adhesive layer I-10 (10 μm) / acrylic adhesive layer IV-5 (5 μm) / PET film (100 μm) was obtained.

[0157] [Example 4] Using one silicone-based adhesive sheet I-10 obtained in Manufacturing Example 1, one acrylic-based adhesive sheet V-10 obtained in Manufacturing Example 5, and one acrylic-based adhesive sheet V-5 obtained in Manufacturing Example 5, an adhesive sheet having a three-layer adhesive structure and a simulated flexible device were manufactured in the same manner as in Example 1. Specifically, an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer V-10 (10 μm) / silicone-based adhesive layer I-10 (10 μm) / acrylic adhesive layer V-5 (5 μm) / double-peel release sheet was obtained, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer V-10 (10 μm) / silicone-based adhesive layer I-10 (10 μm) / acrylic adhesive layer V-5 (5 μm) / PET film (100 μm) was obtained.

[0158] [Example 5] Using one silicone-based adhesive sheet I-5 obtained in Manufacturing Example 1 and two acrylic-based adhesive sheets V-10 obtained in Manufacturing Example 5, an adhesive sheet having a three-layer adhesive structure and a simulated flexible device were manufactured in the same manner as in Example 1. Specifically, an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer V-10 (10 μm) / silicone-based adhesive layer I-5 (5 μm) / acrylic adhesive layer V-10 (10 μm) / double-peel release sheet was obtained, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer V-10 (10 μm) / silicone-based adhesive layer I-5 (5 μm) / acrylic adhesive layer V-10 (10 μm) / PET film (100 μm) was obtained.

[0159] [Comparative Example 1] Using one silicone-based adhesive sheet III-10 obtained in Manufacturing Example 3, one acrylic-based adhesive sheet IV-10 obtained in Manufacturing Example 4, and one acrylic-based adhesive sheet IV-5 obtained in Manufacturing Example 4, an attempt was made to manufacture an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer IV-10 (10 μm) / silicone-based adhesive layer III-10 (10 μm) / acrylic adhesive layer IV-5 (5 μm) / double-peel release sheet, in the same manner as in Example 1. However, the acrylic adhesive layer IV-10 and the silicone-based adhesive layer III-10 could not adhere to each other, and the silicone-based adhesive layer III-10 and the acrylic adhesive layer IV-5 could not adhere to each other, so the above adhesive sheet could not be manufactured.

[0160] [Comparative Example 2] Instead of a silicone adhesive sheet, one sheet of PET film (Unitika Corporation, product name "Emblet PET-12", thickness 12 μm), one sheet of acrylic adhesive sheet IV-10 obtained in Manufacturing Example 4, and one sheet of acrylic adhesive sheet IV-5 obtained in Manufacturing Example 4 were used, and an adhesive sheet and a simulated flexible device were manufactured in the same manner as in Example 1. Specifically, an adhesive sheet consisting of a laminate of a double-peel release sheet / acrylic adhesive layer IV-10 (10 μm) / PET film (12 μm) / acrylic adhesive layer IV-5 (5 μm) / double-peel release sheet was obtained, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer IV-10 (10 μm) / PET film (12 μm) / acrylic adhesive layer IV-5 (5 μm) / PET film (100 μm) was obtained.

[0161] [Comparative Example 3] The acrylic adhesive sheet IV-25 obtained in Manufacturing Example 4 was used as the adhesive sheet for Comparative Example 3, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer IV-25 (25 μm) / PET film (100 μm) was obtained using this adhesive sheet.

[0162] [Comparative Example 4] The acrylic adhesive sheet V-25 obtained in Manufacturing Example 5 was used as the adhesive sheet for Comparative Example 4, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer V-25 (25 μm) / PET film (100 μm) was obtained using this adhesive sheet.

[0163] [Comparative Example 5] The acrylic adhesive sheet VI-25 obtained in Manufacturing Example 6 was used as the adhesive sheet for Comparative Example 5, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer VI-25 (25 μm) / PET film (100 μm) was obtained using this adhesive sheet.

[0164] [Comparative Example 6] The acrylic adhesive sheet VII-25 obtained in Manufacturing Example 7 was used as the adhesive sheet for Comparative Example 6, and a simulated flexible device consisting of a laminate of PET film (100 μm) / acrylic adhesive layer VII-25 (25 μm) / PET film (100 μm) was obtained using this adhesive sheet.

[0165] [Test Example 1] (Measurement of haze value) The adhesive layer of the adhesive sheet produced in each manufacturing example was bonded to glass, and this was used as a measurement sample. After background measurements were performed on the glass, the haze value (%) of the above measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") in accordance with JIS K7136:2000. The results are shown in Tables 1 and 2.

[0166] [Test Example 2] (Measurement of total light transmittance) The adhesive layer of the adhesive sheet produced in each manufacturing example was bonded to glass, and this was used as a measurement sample. After background measurements were performed on the glass, the total light transmittance (%) of the above measurement samples was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7361-1:1997. The results are shown in Tables 1 and 2.

[0167] [Test Example 3] (Measurement of Adhesion) The light-peel release sheet or the first release sheet was peeled off from the adhesive sheet produced in each manufacturing example, and the exposed adhesive layer was laminated to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) having an easy-adhesion layer, to obtain a laminate of heavy-peel release sheet / adhesive layer / PET film. The obtained laminate was cut to a width of 25 mm and a length of 110 mm.

[0168] Under conditions of 23°C and 50%RH, the double-peel release sheet or the second release sheet was peeled from the laminate, and the exposed adhesive layer was attached to a soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., product name "Soda-lime Glass", thickness: 1.1 mm). The plate was then pressurized at 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. After leaving it for 24 hours under conditions of 23°C and 50%RH, the adhesive strength (N / 25 mm) of the laminate of PET film and adhesive layer when peeled from the substrate was measured using a tensile testing machine (manufactured by Orientec, Tensilon) under conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Measurements other than those described herein were performed in accordance with JIS Z0237:2009. The results are shown in Tables 1 and 2.

[0169] [Test Example 4] (Measurement of creep amount) For the adhesive layers of the adhesive sheets in the examples and comparative examples, the creep amount (C1; μm) was measured using a viscoelasticity measuring device (Anton Paar, product name "MCR302") when a shear stress of 2000 kPa was applied for 600 seconds under the following conditions. Subsequently, the creep amount (C2; μm) was measured 20 seconds later with the shear stress applied to the adhesive layer set to 0 kPa. In cases where the adhesive layer contained acrylic adhesive layers of different thicknesses, the shear stress was applied from the side of the thicker acrylic adhesive layer. Measurement temperature: 25℃ Measurement points: 1 point every 20 seconds

[0170] The ratio (%) (C1 / thickness of adhesive layer) × 100) of the creep amount (C1) measured above to the thickness of the adhesive layer (μm) was calculated. Furthermore, based on the creep amounts (C1) and (C2) measured above, the creep change rate (%) was calculated using the following formula (I). The results are shown in Table 3. Creep rate (%) = (1 - C2 / C1) × 100 …(I)

[0171] [Test Example 5] (Wrapping Test) The simulated flexible devices manufactured in the examples and comparative examples were cut to a width of 2.5 cm and a length of 15 cm, and these were used as samples. These samples were wrapped around a cylinder with a diameter of 2.5 cm and left to stand at 23°C for 1 minute. If the adhesive layer of the simulated flexible device contained acrylic adhesive layers of different thicknesses, the thinner acrylic adhesive layer was placed on the inside when wrapping it around the cylinder. At this time, it was visually determined whether delamination occurred between the adhesive layer and the PET film. Based on the results, the wrapping (curvature) was evaluated according to the following criteria. The results are shown in Table 3. ○... No peeling occurred. ×... Delamination occurred.

[0172] Subsequently, the sample was released from the cylinder, one longitudinal end of the sample was fixed to a flat surface, and the height (cm) of the other longitudinal end of the sample from the flat surface was measured. Based on these results, the degree of recovery from curling (bending) was evaluated according to the following criteria. The results are shown in Table 3. ◎...less than 2cm ○...2cm or more, less than 5cm △...5cm or more, less than 7cm ×…7cm or more

[0173] [Table 1]

[0174] [Table 2]

[0175] [Table 3]

[0176] As can be seen from Table 3, the simulated flexible devices manufactured in the examples showed excellent recovery from winding (bending) and were less prone to leaving bending marks. [Industrial applicability]

[0177] The adhesive sheet according to the present invention can be suitably used in rollable displays and the like, and the flexible device according to the present invention can be suitably used as a rollable display and the like. [Explanation of Symbols]

[0178] 1…Adhesive sheet 11…Adhesive layer 111...Acrylic adhesive layer 112…Silicone adhesive layer 12a, 12b… Release sheets 2… Flexible devices 21...First flexible member 22...Second flexible member

Claims

1. An adhesive sheet comprising one or more adhesive layers, At least one layer constituting the adhesive layer is made of an adhesive containing modified cyclodextrin, The adhesive containing the modified cyclodextrin is a silicone-based adhesive. When a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds, the amount of creep is 5% or more as a ratio to the thickness of the adhesive layer. When a shear stress of 2000 kPa is applied to the adhesive layer for 600 seconds, the amount of creep is C1. Then, when the shear stress applied to the adhesive layer is reduced to 0 kPa, the amount of creep measured 20 seconds later is C2. The creep change rate calculated from the following formula (I) is 60% or more. An adhesive sheet characterized by the following features. Creep rate (%) = (1 - C2 / C1) × 100 … (I)

2. The adhesive sheet according to claim 1, characterized in that the adhesive layer consists of multiple layers.

3. The adhesive sheet according to claim 2, characterized in that the thickness of the layer comprising the adhesive containing the modified cyclodextrin is 10% or more and 80% or less of the total thickness of the adhesive layer.

4. The layer comprising the adhesive containing the modified cyclodextrin is made of a silicone-based adhesive. The layers other than the layer containing the modified cyclodextrin adhesive are made of an acrylic adhesive. The adhesive sheet according to feature 2.

5. The adhesive sheet according to claim 4, characterized in that the layer made of the acrylic adhesive is located on both outermost layers of the adhesive layer.

6. The adhesive sheet according to claim 1, characterized in that it is for use with flexible devices.

7. The adhesive sheet according to claim 1, characterized in that it is for use in a rollable device.

8. The adhesive sheet comprises two release sheets. The adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. The adhesive sheet according to feature 1.

9. A flexible device comprising an adhesive layer in an adhesive sheet according to any one of claims 1 to 8.

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