Elastic sheet with adhesive layer and flexible display device using the same

Abstract

The present disclosure addresses the problem of providing an adhesive-layer-equipped elastic sheet with which it is possible to suppress the occurrence of wrinkling in a curved section with respect to a bend at which the bending radius of a display, etc., is very small. This adhesive-layer-equipped elastic sheet (1) comprises: an elastic body layer (2) in which the tensile elasticity at 20°C is at least 80 MPa and less than 1,500 MPa, and in which the tensile elasticity at 85°C is at least 40 MPa and less than 1,000 MPa; and an adhesive layer (3) overlapping the elastic body layer (2). The thickness of the adhesive layer (3) is 2-15 μm. The adhesive force of the adhesive layer (3) with respect to a polyethylene terephthalate film is at least 10 N / 25 mm.

Description

Technical Field

[0001] The present disclosure relates to an elastic sheet with an adhesive layer and a flexible display device, and more particularly to an elastic sheet with an adhesive layer including an elastomer layer and an adhesive layer, and a flexible display device using the same.

Background Art

[0002] In display devices used in various electronic devices such as smartphones, tablet terminals, and notebook personal computers, defects may occur in the appearance of optical films or the like provided on the front side of the display. Regarding such defects, for example, an adhesive composition capable of forming an adhesive layer in which the occurrence of floating or peeling is suppressed even in a high-temperature environment has been studied (see Patent Document 1).

[0003] Recently, in foldable terminals, electronic papers, and the like, flexible displays such as organic ELs have come to be used. However, such flexible displays have a problem that when performing a fold with a very small bending radius, wrinkles occur on the front side of the display at the bending portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] An object of the present disclosure is to provide an elastic sheet with an adhesive layer capable of suppressing the occurrence of wrinkles at the bending portion with respect to a fold having a very small bending radius such as a display, and a flexible display device using the same.

[0006] An elastic sheet with an adhesive layer according to one aspect of the present disclosure comprises an elastic layer having a tensile modulus of 80 MPa or more and less than 1500 MPa at 20°C, and a tensile modulus of 40 MPa or more and less than 1000 MPa at 85°C, and an adhesive layer overlapping the elastic layer. The thickness of the adhesive layer is 2 μm or more and 15 μm or less. The adhesive strength of the adhesive layer to the polyethylene terephthalate film is 10 N / 25 mm or more.

[0007] A flexible display device according to one aspect of the present disclosure is characterized in that the elastic sheet with an adhesive layer is attached to the front side of a flexible display. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure. [Figure 3] Figure 3 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] <Elastic sheet with adhesive layer> The elastic sheet with an adhesive layer according to this embodiment (hereinafter also referred to as elastic sheet 1) comprises an elastic layer having a tensile modulus of 80 MPa or more and less than 1500 MPa at 20°C, and a tensile modulus of 40 MPa or more and less than 1000 MPa at 85°C, and an adhesive layer overlapping the elastic layer. The thickness of the adhesive layer is 2 μm or more and 15 μm or less. The adhesive strength of the adhesive layer to the polyethylene terephthalate film is 10 N / 25 mm or more.

[0010] In a foldable display, when a thin film such as polyethylene terephthalate or polyimide, placed on the front side (display surface side) of the display, is bent, tensile and compressive stresses concentrate simultaneously, causing structural deformation and delamination of the thin film, resulting in wrinkles. The inventors have found that by placing an elastic sheet with an adhesive layer around the thin film, the tensile and compressive stresses during bending are relieved, thereby suppressing structural deformation and delamination of the thin film and preventing wrinkle formation. Furthermore, the inventors have found a relationship between the relief of tensile and compressive stresses and the tensile modulus of the elastic layer of the elastic sheet 1. That is, if the tensile modulus is 80 MPa or more and less than 1500 MPa at 20°C and 40 MPa or more and less than 1000 MPa at 85°C, it is considered that the stress during bending can be well distributed under each temperature condition, and the tensile and compressive stresses can be sufficiently relieved in the bent portion. If the tensile modulus is outside the above range at either 20°C or 85°C, there is a risk that the tensile and compressive stresses cannot be sufficiently relieved. Furthermore, it was found that the adhesive layer of the elastic sheet 1 must have a thickness of 2 μm or more and 15 μm or less, and an adhesive strength of 10 N / 25 mm or more to polyethylene terephthalate film. If the thickness of the adhesive layer is less than 2 μm, delamination may occur in the adhesive layer, and if it exceeds 15 μm, structural deformation of the flexible adhesive layer may occur. If the adhesive strength is less than 10 N / 25 mm, delamination may occur in the adhesive layer. By satisfying all of these conditions, the elastic sheet 1 can suppress the occurrence of wrinkles in bent sections with a tight radius of curvature, for example, up to Φ1.5 mm. Thus, according to this disclosure, it is possible to provide an elastic sheet with an adhesive layer that can suppress the occurrence of wrinkles in bent sections when used in displays, etc., even when bending with a very small bending radius.

[0011] Figure 1 shows an example of the elastic sheet of this embodiment. The elastic sheet 1 in Figure 1 comprises an elastic layer 2 and an adhesive layer 3 that directly overlaps the elastic layer 2.

[0012] [Elastic layer] The elastic layer 2 has a tensile modulus of 80 MPa or more and less than 1500 MPa at 20°C, and 40 MPa or more and less than 1000 MPa at 85°C. The tensile modulus at 20°C is preferably 100 MPa or more, more preferably 150 MPa or more, even more preferably 200 MPa or more, and particularly preferably 300 MPa or more. The tensile modulus at 20°C is preferably 1450 MPa or less, more preferably 1400 MPa or less, even more preferably 1350 MPa or less, and particularly preferably 1300 MPa or less. The tensile modulus at 85°C is preferably 70 MPa or more, more preferably 100 MPa or more, and even more preferably 150 MPa or more. The tensile modulus at 85°C is preferably 900 MPa or less, more preferably 800 MPa or less, and even more preferably 700 MPa or less. By setting the tensile modulus within the above range, tensile stress and compressive stress can be further relaxed, and as a result, the occurrence of wrinkles can be further suppressed.

[0013] The elastic sheet 1 may have one elastic layer 2 or two or more layers, but usually it has one layer. The shape of the elastic layer 2 may be, for example, a film, a sheet, a plate, etc.

[0014] Here, the tensile modulus of elastic layer 2 is a value measured by performing a dynamic viscoelasticity test. In the dynamic viscoelasticity test, a test specimen is prepared from elastic layer 2, and the tensile modulus (MPa) is measured at 20°C and 85°C under the conditions of a frequency of 10 Hz and a heating rate of 5°C / min. The method for measuring the tensile modulus will be explained in the Examples section below.

[0015] The flexural modulus of the material constituting the elastic layer 2 is preferably 100 MPa or more and 2500 MPa or less. In this case, tensile stress and compressive stress can be further relaxed, and as a result, the occurrence of wrinkles can be further suppressed. The flexural modulus is more preferably 300 MPa or more, even more preferably 500 MPa or more, and particularly preferably 650 MPa or more. The flexural modulus is more preferably 2300 MPa or less, even more preferably 2100 MPa or less, and particularly preferably 1500 MPa or less.

[0016] Here, the flexural modulus of the material constituting the elastic layer 2 is the value measured in accordance with JIS-K7171, under conditions of an indenter radius of 5 mm and a compression speed of 2 mm / min. The method for measuring the flexural modulus will be explained in the Examples section below.

[0017] The thickness of the elastic layer 2 is preferably 30 μm or more. In this case, the stress relaxation ability is further improved and the occurrence of wrinkles can be further suppressed. This thickness is more preferably 40 μm or more, and even more preferably 50 μm or more. The thickness of the elastic layer 2 is preferably 290 μm or less. In this case, the elastic sheet 1 can be made thinner. This thickness is more preferably 200 μm or less, and even more preferably 100 μm or less.

[0018] The material constituting the elastic layer 2 is not particularly limited as long as the tensile modulus of the elastic layer 2 is within the aforementioned range, and examples include the following elastomers.

[0019] Examples of elastomers include acrylic elastomers, urethane elastomers, olefin elastomers, amide elastomers, styrene elastomers, and ester elastomers.

[0020] Examples of acrylic elastomers include copolymers in which the hard segment contains (meth)acrylate units and the soft segment contains acrylonitrile units, ethylene units, (meth)acrylate units, etc. The (meth)acrylate units include both acrylate units and methacrylate units.

[0021] Examples of urethane elastomers include copolymers in which the hard segment contains a polyurethane structure and the soft segment contains a polyester structure, a polyether structure, a polycaprolactone structure, etc.

[0022] Examples of olefin elastomers include polymer alloys in which an olefin rubber such as ethylene - propylene rubber or ethylene - propylene - diene terpolymer is finely dispersed in a matrix of an olefin resin such as polypropylene or polyethylene; copolymers in which the hard segment contains a polybutadiene structure and the soft segment contains a polyether structure, a polyester structure, etc.

[0023] Examples of amide elastomers include copolymers in which the hard segment contains a polyamide structure and the soft segment contains a polyether structure, a polyester structure, etc.

[0024] Examples of styrene elastomers include copolymers in which the hard segment contains styrene units and the soft segment contains butadiene units or hydrogenated butadiene units, or isoprene units or hydrogenated isoprene units, etc.

[0025] Examples of ester elastomers include copolymers in which the hard segment contains a polyester structure and the soft segment contains a polyether structure, a polyester structure, etc.

[0026] The material constituting the elastic layer 2 preferably contains an elastomer, and from the viewpoint of adhesion, transparency, and weather resistance, it is preferable that it contains an acrylic elastomer.

[0027] Examples of (meth)acrylic acid ester units in acrylic elastomers include methyl (meth)acrylate units; ethyl (meth)acrylate units; propyl (meth)acrylate units such as n-propyl (meth)acrylate units and iso-propyl (meth)acrylate units; butyl (meth)acrylate units such as n-butyl (meth)acrylate units, iso-butyl (meth)acrylate units, sec-butyl (meth)acrylate units and tert-butyl (meth)acrylate units; pentyl (meth)acrylate units; hexyl (meth)acrylate units; and cyclohexyl (meth)acrylate units. Examples include alkyl(meth)acrylates such as acrylate units; heptyl(meth)acrylate units; n-octyl(meth)acrylate units, 2-ethylhexyl(meth)acrylate units, etc.; nonyl(meth)acrylate units; decyl(meth)acrylate units; undecyl(meth)acrylate units; dodecyl(meth)acrylate units; tridecyl(meth)acrylate units; tetradecyl(meth)acrylate units; hexadecyl(meth)acrylate units; octadecyl(meth)acrylate units; and icosyl(meth)acrylate units.

[0028] Acrylic elastomers may have units derived from other monomers in addition to (meth)acrylic acid ester units. Examples of other monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; glycerin di(meth)acrylate, glycidyl (meth)acrylate, 2-(meth)acryloyloxyethyl isocyanate, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, and fumaric acid.

[0029] For monomers that provide hard segments of acrylic elastomers, it is preferable that the homopolymer has a glass transition temperature (Tg) of 60°C or higher. For monomers that provide soft segments of acrylic elastomers, it is preferable that the homopolymer has a Tg of -10°C or lower. Examples of monomers with a homopolymer Tg of 60°C or higher include methyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate. Examples of monomers with a homopolymer Tg of -10°C or lower include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-octyl acrylate, isononyl acrylate, and lauryl methacrylate.

[0030] The ratio of units constituting the hard segment to the total units of the acrylic elastomer is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more. This ratio is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less. By setting the ratio of hard segments within the above range, the tensile modulus of the elastic layer can be adjusted to a more appropriate level, and as a result, the occurrence of wrinkles can be further suppressed.

[0031] From the viewpoint of superior adhesiveness, transparency, and weather resistance, the acrylic elastomer preferably contains a resin having butyl acrylate units and methyl methacrylate units, more preferably a block copolymer in which the soft segment contains butyl acrylate units and the hard segment contains methyl methacrylate units, and even more preferably a triblock copolymer composed of methyl methacrylate block-butyl acrylate block-methyl methacrylate block. The ratio of butyl acrylate units to the total units of the resin is preferably 10% by mass or more and 60% by mass or less, and more preferably 25% by mass or more and 50% by mass or less. The ratio of methyl methacrylate units to the total units of the resin is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 75% by mass or less.

[0032] Examples of commercially available acrylic elastomers include Clarity LA4286, LA2250, and LA2270 from Kuraray Co., Ltd.

[0033] The method for forming the elastic layer 2 is not particularly limited, but examples include a method in which the material constituting the elastic layer 2 is dissolved in a solvent, coated, and dried to obtain a cast film, or a method in which the material constituting the elastic layer 2 is formed by a T-die method or an inflation deposition method to obtain a film.

[0034] [Adhesive layer] The adhesive layer 3 is placed on top of the elastic layer 2. The elastic sheet 1 may have one, two, or three or more layers of the adhesive layer 3.

[0035] The shape of the adhesive layer 3 can be, for example, a film, a sheet, or a plate.

[0036] The thickness of the adhesive layer 3 is 2 μm or more and 15 μm or less. Preferably, the thickness of the adhesive layer 3 is 4 μm or more, more preferably 6 μm or more, even more preferably 8 μm or more, and particularly preferably 9 μm or more. In this case, the stress relaxation ability of the elastic sheet 1 is further improved, and as a result, the occurrence of wrinkles can be further suppressed. Preferably, the thickness of the adhesive layer 3 is 12 μm or less, and more preferably 10 μm or less. This thickness of the adhesive layer 3 refers to the thickness of one adhesive layer.

[0037] The adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film is 10 N / 25 mm or more. Preferably, the adhesive strength is 12 N / 25 mm or more, more preferably 14 N / 25 mm or more, and even more preferably 15 N / 25 mm or more. In this case, the occurrence of wrinkles can be further suppressed.

[0038] The adhesive layer 3 can be formed from, for example, an adhesive. This adhesive is not particularly limited and can be used as long as it can provide the adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film within the aforementioned range.

[0039] Examples of adhesives include acrylic adhesives, urethane adhesives, and polyester adhesives. From the viewpoint of achieving greater adhesive strength, it is preferable that the adhesive includes an acrylic adhesive.

[0040] Examples of acrylic adhesives include methyl (meth)acrylate; ethyl (meth)acrylate; butyl (meth)acrylates such as n-butyl (meth)acrylate and iso-butyl (meth)acrylate; alkyl (meth)acrylates such as 2-ethylhexyl (meth)acrylate; dodecyl (meth)acrylate; octadecyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and butoxymethyl (meth)acrylate; cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, vinyl acetate; (meth)acrylamides such as (meth)acrylamide and N-methylol (meth)acrylamide; and homopolymers or copolymers of monomers such as styrene, acrylonitrile, vinylpyridine, vinylpyrrolidone, and vinyl alkyl ethers.

[0041] The method for forming the adhesive layer 3 is not particularly limited, but examples include a method of forming it by applying an adhesive to the surface of the elastic layer 2, or a method of forming it by co-extruding the material constituting the elastic layer 2 and the adhesive.

[0042] [Other layers] The elastic sheet 1 may include other layers besides the elastic layer 2 and the adhesive layer 3. The elastic sheet 1 may include one or more of these other layers. The shape of the other layers may be, for example, a film, a sheet, a plate, etc.

[0043] The elastic sheet 1 may also include other layers, such as an impact-absorbing layer 5 between the elastic layer 2 and the adhesive layer 3 to absorb shocks and vibrations. Furthermore, the elastic sheet 1 may also include other layers, such as a protective layer like a separator on the side of the adhesive layer 3 opposite to the elastic layer 2.

[0044] [Layer composition] Examples of the layer configuration of the adhesive elastic sheet according to this embodiment include (a) to (l) below. In the following, the notation A / B / C indicates, for example, that the layers are stacked in the order of A, B, and C from the frontmost surface of the display device. (a) Adhesive layer / elastic layer (b) Adhesive layer / Elastic layer / Adhesive layer (c) Adhesive layer / Shock absorbing layer / Elastic layer (d) Adhesive layer / Shock-absorbing layer / Elastic layer / Adhesive layer (e) Adhesive layer / Shock absorbing layer / Elastic layer / Shock absorbing layer (f) Adhesive layer / Shock-absorbing layer / Elastic layer / Shock-absorbing layer / Adhesive layer (g) Separator / Adhesive layer / Elastic layer (h) Separator / Adhesive layer / Elastic layer / Adhesive layer / Separator (i) Separator / Adhesive layer / Shock-absorbing layer / Elastic layer (j) Separator / Adhesive layer / Shock absorbing layer / Elastic layer / Adhesive layer / Separator (k) Separator / Adhesive layer / Shock absorbing layer / Elastic layer / Shock absorbing layer (l) Separator / Adhesive layer / Shock absorbing layer / Elastic layer / Shock absorbing layer / Adhesive layer / Separator

[0045] Figure 2 shows an elastic sheet with an adhesive layer having the layer configuration described in (h) above. The elastic sheet 1 in Figure 2 comprises an elastic body layer 2, two adhesive layers 3, 3 directly laminated on both sides of the elastic body layer 2, and two separators 4, 4 directly laminated on these adhesive layers 3, 3.

[0046] Figure 3 shows an elastic sheet with an adhesive layer having the layer configuration of (j) described above. The elastic sheet 1 in Figure 3 comprises an elastic body layer 2, an impact absorbing layer 5 directly laminated to one side of the elastic body layer 2, two adhesive layers 3, 3 directly laminated to one side of the elastic body layer 2 and one side of the impact absorbing layer 5, and two separators 4, 4 directly laminated to these adhesive layers 3, 3.

[0047] The total thickness of the elastic layer 2 and the adhesive layer 3 in the elastic sheet 1 is preferably 50 μm or more. In this case, the stress relaxation ability of the elastic sheet 1 can be further improved, and as a result, the occurrence of wrinkles can be further suppressed. This thickness is more preferably 60 μm or more, and even more preferably 70 μm or more. The total thickness is preferably 300 μm or less. In this case, the display device, including the display, can be made thinner. The total thickness is more preferably 200 μm or less, and even more preferably 100 μm or less.

[0048] The thickness of the elastic sheet 1 is preferably 50 μm or more. In this case, the strength of the elastic sheet 1 can be further improved. This thickness is more preferably 60 μm or more, and even more preferably 70 μm or more. The thickness of the elastic sheet 1 is preferably 300 μm or less. In this case, the display device including the display can be made thinner. This thickness is more preferably 200 μm or less, and even more preferably 100 μm or less.

[0049] The elastic sheet 1 according to this embodiment can be suitably used for flexible displays. The elastic sheet 1 is preferably placed on the front side of the flexible display, that is, it is preferably used by being attached to the front side of the flexible display, and more preferably it is used by being directly laminated to a protective film, coating layer, etc., made of polyethylene terephthalate or polyimide, which is placed at the very front of the display device. By placing the elastic sheet 1 according to this embodiment on the front side of the display of a display device including a flexible display, it is possible to provide a flexible display device in which the occurrence of wrinkles at the bent portion is suppressed even when the bending radius of the display device is very small. [Examples]

[0050] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to these examples.

[0051] 1. Preparation of an elastic sheet with an adhesive layer The materials constituting the elastic layer and the adhesive layer are as follows: -Material of the elastic layer • Resin A: Methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer. Or, a mixed resin of methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer and polymethyl methacrylate. The resin A solutions used in each example were prepared by dissolving pellets of Clarity (manufactured by Kuraray Co., Ltd.) product numbers LA4285, LA2250, LA2270 and Dianal (manufactured by Mitsubishi Chemical Corporation) product number BR-87 in a solvent, and the resulting solutions were prepared accordingly. solution Two of these were mixed to prepare the mixture in the proportions (mass%) of BA units (n-butyl acrylate units) and MMA units (methyl methacrylate units) shown in Table 1. - Material of the adhesive layer • Acrylic adhesive. Manufactured by Soken Chemical Co., Ltd. Product name: SK Dyne. Part number: SK1717DT. Contains 2-ethylhexyl acrylate, butyl acrylate, and 2-hydroxyethyl acrylate.

[0052] A cast film with the thickness of the elastic layer shown in Table 1 was produced by applying a solution of the prepared elastic layer material (resin A) and drying it, thereby obtaining the elastic layer. Next, an adhesive layer 1 with the thickness shown in Table 1 was formed by applying an adhesive layer material (acrylic adhesive) to one side of this elastic layer and drying it. Then, an adhesive layer with the thickness shown in Table 1 was formed on the side of the elastic layer opposite to adhesive layer 1 in the same manner as above by applying the acrylic adhesive and drying it. In this way, an elastic sheet with an adhesive layer was produced.

[0053] 2. Evaluation (1) Tensile modulus of elastic layer An elastic layer was obtained from an elastic sheet with an adhesive layer, and a test specimen measuring 10 mm in width and 20 mm in length was prepared from this elastic layer. The tensile modulus (MPa) of this test specimen was measured at 20°C and 85°C using a dynamic viscoelasticity measuring device (DVA-200, manufactured by IT Measurement Control Co., Ltd.) under the conditions of a frequency of 10 Hz and a heating rate of 5°C / min.

[0054] (2) Flexural modulus of the material constituting the elastic layer An elastic layer was obtained from an elastic sheet with an adhesive layer, and a test specimen measuring 10 mm in width and 80 mm in length was prepared from this elastic layer. The flexural modulus (MPa) of this test specimen was measured at 23°C in accordance with JIS-K7171 (Plastics - Method for determining bending properties), under conditions of an indenter radius of 5 mm and a compression speed of 2 mm / min.

[0055] (3) Adhesion of the adhesive layer to the polyethylene terephthalate film The adhesive strength of the adhesive layer to the polyethylene terephthalate film was measured in an environment of 23°C by preparing a test piece measuring 25 mm wide x 100 mm long by laminating a polyethylene terephthalate film (25 μm thick, manufactured by Toyobo Co., Ltd., product number E5100) to the adhesive layer 1 of an elastic sheet with an adhesive layer, and using a method compliant with JIS-Z0237:2009 "Test Method for Adhesive Tapes and Adhesive Sheets" (lamination conditions: 2 kg roller, 1 back-and-forth, peeling speed: 300 mm / min, peeling angle: 180°).

[0056] (4) Flexion test A flexural test sample measuring 20 mm in width and 150 mm in length was prepared by laminating polyethylene terephthalate film (25 μm thick, manufactured by Toyobo Co., Ltd., product number E5100) to both sides of an adhesive-backed elastic sheet. A flexural test was performed on this sample using a flexural test apparatus (manufactured by Yuasa Corporation). The flexural test conditions were a radius of curvature R = 2.5 mm, a flexural speed of 90 cycles / minute, and a total of 10,000 flexural cycles. After the flexural test, the sample was visually inspected to check for the presence or absence of wrinkles. If no wrinkles were present, it was evaluated as "OK"; if wrinkles were present, it was evaluated as "NG".

[0057] [Table 1] [Explanation of Symbols]

[0058] 1. Elastic sheet with adhesive layer 2 Elastic layer 3 Adhesive layer 4 Separators 5. Shock-absorbing layer

Claims

1. An elastic layer having a tensile modulus of 80 MPa or more and less than 1500 MPa at 20°C, and a tensile modulus of 40 MPa or more and less than 1000 MPa at 85°C, An adhesive layer overlapping the aforementioned elastic layer and Equipped with, The elastic layer comprises a resin having butyl acrylate units and methyl methacrylate units. The thickness of one layer of the adhesive layer is 2 μm or more and 15 μm or less. An elastic sheet with an adhesive layer, wherein the adhesive strength of the adhesive layer to the polyethylene terephthalate film is 10 N / 25 mm or more.

2. The elastic sheet with an adhesive layer according to claim 1, wherein the thickness of the elastic layer is 50 μm or more and 290 μm or less.

3. The elastic sheet with adhesive layer according to claim 1 or 2, wherein the total thickness of the elastic layer and the adhesive layer is 50 μm or more and 300 μm or less.

4. An elastic sheet with an adhesive layer according to any one of claims 1 to 3, for use in flexible displays.

5. A flexible display device in which an elastic sheet with an adhesive layer according to any one of claims 1 to 3 is attached to the front side of a flexible display.

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