WO2022181656A1 - Adhesive-layer-equipped elastic sheet, and flexible display device in which same is used - Google Patents

Adhesive-layer-equipped elastic sheet, and flexible display device in which same is used Download PDF

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Publication number
WO2022181656A1
WO2022181656A1 PCT/JP2022/007470 JP2022007470W WO2022181656A1 WO 2022181656 A1 WO2022181656 A1 WO 2022181656A1 JP 2022007470 W JP2022007470 W JP 2022007470W WO 2022181656 A1 WO2022181656 A1 WO 2022181656A1
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layer
adhesive layer
elastic
adhesive
mpa
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PCT/JP2022/007470
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French (fr)
Japanese (ja)
Inventor
翔 英
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パナソニックＩｐマネジメント株式会社
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Priority to CN202280015843.1A priority Critical patent/CN117062887A/en
Priority to JP2023502463A priority patent/JPWO2022181656A1/ja
Priority to KR1020237028053A priority patent/KR20230151998A/en
Publication of WO2022181656A1 publication Critical patent/WO2022181656A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/022—Mechanical properties
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature

Definitions

  • the present disclosure relates to an adhesive layer-attached elastic sheet and a flexible display device, and more specifically, to an adhesive layer-attached elastic sheet including an elastic layer and an adhesive layer, and a flexible display device using the same.
  • the optical film, etc. provided on the front side of the display may cause defects in appearance.
  • a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer in which the occurrence of lifting and peeling is suppressed even in a high-temperature environment has been investigated (see Patent Document 1).
  • An object of the present disclosure is to provide an adhesive layer-attached elastic sheet capable of suppressing the occurrence of wrinkles in a bent portion when a display or the like is bent with a very small bending radius, and a flexible display device using the same. to do.
  • An elastic sheet with an adhesive layer includes an elastic layer having a tensile modulus of elasticity of 80 MPa or more and less than 1500 MPa at 20°C and a modulus of elasticity in tension of 40 MPa or more and less than 1000 MPa at 85°C; and an adhesive layer overlying the layers.
  • the thickness of the adhesive layer is 2 ⁇ m or more and 15 ⁇ m or less.
  • the adhesive layer has an adhesive strength of 10 N/25 mm or more to the polyethylene terephthalate film.
  • the elastic sheet with an adhesive layer is attached to the front side of a flexible display.
  • FIG. 1 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to one embodiment of the present disclosure.
  • FIG. 2 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure.
  • FIG. 3 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure.
  • the adhesive layer-attached elastic sheet (hereinafter also referred to as elastic sheet 1) according to the present embodiment has a tensile modulus of elasticity of 80 MPa or more and less than 1500 MPa at 20°C and a tensile modulus of elasticity of 40 MPa or more and less than 1000 MPa at 85°C.
  • a body layer and an adhesive layer overlapping the elastic layer are provided.
  • the thickness of the adhesive layer is 2 ⁇ m or more and 15 ⁇ m or less.
  • the adhesive layer has an adhesive strength of 10 N/25 mm or more to the polyethylene terephthalate film.
  • a bendable display when a thin film such as polyethylene terephthalate or polyimide placed on the front side of the display (the display surface side of the display) is bent, the tensile stress and the compressive stress concentrate at the same time, and the thin film Structural deformation and peeling of films and the like occur, and wrinkles occur.
  • the present inventors arranged an elastic sheet with an adhesive layer around the thin film or the like to reduce tensile stress and compressive stress in bending, thereby suppressing structural deformation and peeling of the thin film or the like. , it was found that the occurrence of wrinkles can be suppressed.
  • the present inventors also found that there is a relationship between the relaxation of tensile stress and compressive stress and the tensile elastic 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., the stress during bending can be well dispersed under each temperature condition. It is believed that tensile stress and compressive stress can be sufficiently relieved. If the tensile elastic modulus is outside the above range at either one of 20°C and 85°C, there is a possibility that tensile stress and compressive stress cannot be sufficiently relaxed.
  • the adhesive layer of the elastic sheet 1 needs to have a thickness of 2 ⁇ m or more and 15 ⁇ m or less and an adhesive force to the polyethylene terephthalate film of 10 N/25 mm or more. . If the thickness of the adhesive layer is less than 2 ⁇ m, peeling may occur in the adhesive layer, and if it exceeds 15 ⁇ m, structural deformation of the flexible adhesive layer may occur. If the adhesive strength is less than 10 N/25 mm, the adhesive layer may peel off. By satisfying all of these, the elastic sheet 1 can suppress the generation of wrinkles at a bending portion with a severe radius of curvature up to ⁇ 1.5 mm, for example. As described above, according to the present disclosure, it is possible to provide an adhesive layer-attached elastic sheet that can suppress the occurrence of wrinkles at the bent portion when bent with a very small bending radius by being used for a display or the like. can.
  • FIG. 1 shows an example of the elastic sheet of this embodiment.
  • the elastic sheet 1 of FIG. 1 includes an elastic layer 2 and an adhesive layer 3 directly overlapping the elastic layer 2 .
  • 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, still 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 900 MPa or less, more preferably 800 MPa or less, and even more preferably 700 MPa or less.
  • the elastic sheet 1 may have one elastic layer 2 or two or more layers, but usually has one layer.
  • the shape of the elastic layer 2 is, for example, film-like, sheet-like, or plate-like.
  • the tensile elastic modulus of the elastic layer 2 is a value measured by performing a dynamic viscoelasticity test.
  • a test piece is prepared from the 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.
  • MPa tensile modulus
  • the flexural modulus of the material forming 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 more relaxed, and as a result, the occurrence of wrinkles can be further suppressed.
  • the bending elastic modulus is more preferably 300 MPa or more, further preferably 500 MPa or more, and particularly preferably 650 MPa or more.
  • the bending elastic modulus is more preferably 2300 MPa or less, further preferably 2100 MPa or less, and particularly preferably 1500 MPa or less.
  • the flexural modulus of the material forming the elastic layer 2 is a value measured in accordance with JIS-K7171 under conditions of an indenter radius of 5 mm and a compression rate of 2 mm/min. A method for measuring the flexural modulus will be described in the Examples section below.
  • the thickness of the elastic layer 2 is preferably 30 ⁇ m 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 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the thickness of the elastic layer 2 is preferably 290 ⁇ m or less. In this case, the thickness of the elastic sheet 1 can be further reduced. This thickness is more preferably 200 ⁇ m or less, and even more preferably 100 ⁇ m or less.
  • the material constituting the elastic layer 2 is not particularly limited as long as the elastic modulus in tension of the elastic layer 2 is within the above range, and examples thereof include the following elastomers.
  • elastomers examples include acrylic elastomers, urethane elastomers, olefin elastomers, amide elastomers, styrene elastomers, and ester elastomers.
  • acrylic elastomers include copolymers in which the hard segment contains (meth)acrylic acid ester units and the soft segment contains acrylonitrile units, ethylene units, (meth)acrylic acid ester units, and the like.
  • the (meth)acrylic acid ester unit includes both an acrylic acid ester unit and a methacrylic acid ester unit.
  • urethane-based elastomers include copolymers in which the hard segment includes a polyurethane structure and the soft segment includes a polyester structure, polyether structure, polycaprolactone structure, or the like.
  • olefinic elastomer for example, a polymer alloy obtained by finely dispersing an olefinic rubber such as an ethylene/propylene rubber or an ethylene/propylene/diene terpolymer in a matrix of an olefinic resin such as polypropylene or polyethylene; contains a polybutadiene structure, and the soft segment contains a polyether structure, a polyester structure, or the like.
  • amide-based elastomers include copolymers in which the hard segment contains a polyamide structure and the soft segment contains a polyether structure, polyester structure, or the like.
  • styrene-based 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.
  • ester-based elastomers include copolymers in which the hard segment contains a polyester structure and the soft segment contains a polyether structure, polyester structure, or the like.
  • the material constituting the elastic layer 2 preferably contains an elastomer, and preferably contains an acrylic elastomer from the viewpoint of adhesiveness, transparency and weather resistance.
  • Examples of the (meth)acrylic acid ester units of the acrylic elastomer include methyl (meth)acrylate units; ethyl (meth)acrylate units; n-propyl (meth)acrylate units, iso-propyl (meth)acrylate units and other 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, tert-butyl (meth)acrylate units; pentyl (Meth) acrylate units; hexyl (meth) acrylate units; cyclohexyl (meth) acrylate units; heptyl (meth) acrylate units; ) acrylate unit; nonyl (meth) acrylate unit; decyl (meth) acrylate unit; undecyl (meth) acrylate unit
  • the acrylic elastomer may have units derived from other monomers in addition to the (meth)acrylic acid ester units.
  • Other monomers include, for example, 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, fumaric acid and the like.
  • the monomer that provides the hard segment of the acrylic elastomer preferably has a homopolymer glass transition temperature (Tg) of 60°C or higher.
  • the monomer that provides the soft segment of the acrylic elastomer preferably has a homopolymer Tg of -10°C or lower.
  • Monomers whose homopolymer Tg is 60° C. or higher include, for example, methyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate.
  • n-butyl acrylate 2-ethylhexyl acrylate, isooctyl acrylate, n-octyl acrylate, isononyl acrylate, lauryl methacrylate and the like.
  • the ratio of the 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, further preferably 40% by mass or more, and 50% by mass or more. % by mass or more is particularly preferred. This proportion 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.
  • the acrylic elastomer preferably contains a resin having a butyl acrylate unit and a methyl methacrylate unit from the viewpoint of superior adhesiveness, transparency, and weather resistance, the soft segment containing the butyl acrylate unit, and the hard segment containing methyl methacrylate. It more preferably contains a block copolymer containing units, and more preferably contains a triblock copolymer composed of a methyl methacrylate block-butyl acrylate block-methyl methacrylate block.
  • the ratio of butyl acrylate units to all units of the resin is preferably 10% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less.
  • the ratio of methyl methacrylate units to all units of the resin is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 75% by mass or less.
  • acrylic elastomers include Clarity LA4286, LA2250 and LA2270 manufactured by Kuraray Co., Ltd., for example.
  • the method of forming the elastic layer 2 is not particularly limited. Examples include a method of obtaining a film by molding by a die method, an inflation film forming method, or the like.
  • the adhesive layer 3 is placed over the elastic layer 2 .
  • the elastic sheet 1 may have one adhesive layer 3, two layers, or three or more layers.
  • the shape of the adhesive layer 3 is, for example, film-like, sheet-like, or plate-like.
  • the thickness of the adhesive layer 3 is 2 ⁇ m or more and 15 ⁇ m or less.
  • the thickness of the adhesive layer 3 is preferably 4 ⁇ m or more, more preferably 6 ⁇ m or more, still more preferably 8 ⁇ m or more, and particularly preferably 9 ⁇ m 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.
  • the thickness of the adhesive layer 3 is preferably 12 ⁇ m or less, more preferably 10 ⁇ m or less.
  • the thickness of the adhesive layer 3 refers to the thickness of one adhesive layer.
  • the adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film is 10 N/25 mm or more.
  • the adhesive strength is preferably 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.
  • the adhesive layer 3 can be formed, for example, from an adhesive. Any adhesive can be used without particular limitation as long as the adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film can be within the above range.
  • adhesives examples include acrylic adhesives, urethane adhesives, and polyester adhesives.
  • the adhesive preferably contains an acrylic adhesive from the viewpoint of increasing the adhesive strength.
  • acrylic adhesives examples include methyl (meth) acrylate; ethyl (meth) acrylate; butyl (meth) acrylate such as n-butyl (meth) acrylate and iso-butyl (meth) acrylate; 2-ethylhexyl (meth) acrylate.
  • dodecyl (meth)acrylate alkyl (meth)acrylates such as octadecyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; methoxyethyl (meth)acrylate, butoxymethyl (meth)acrylate alkoxyalkyl (meth)acrylates such as; cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, vinyl acetate; (meth)acrylamides such as (meth)acrylamide and N-methylol (meth)acrylamide; styrene , acrylonitrile, vinylpyridine, vinylpyrrolidone, vinylalkyl ether, and the like.
  • the method of forming the adhesive layer 3 is not particularly limited, but for example, a method of applying an adhesive to the surface of the elastic layer 2 to form it, or a method of co-extrusion of the material constituting the elastic layer 2 and an adhesive. and methods to do so.
  • the elastic sheet 1 may include other layers in addition to the elastic layer 2 and the adhesive layer 3 .
  • the elastic sheet 1 may comprise one or more other layers.
  • the shape of other layers is, for example, film-like, sheet-like, or plate-like.
  • the elastic sheet 1 may include, as another layer, a shock absorbing layer 5 for absorbing shock and vibration between the elastic layer 2 and the adhesive layer 3, for example.
  • the elastic sheet 1 may also include a protective layer such as a separator on the side of the adhesive layer 3 opposite to the elastic layer 2 as another layer.
  • Examples of the layer structure of the adhesive layer-attached elastic sheet according to the present embodiment include the following (a) to (l).
  • the notation of A/B/C indicates that layers are laminated in order of A, B, and C from the front surface of the display device, for example.
  • Adhesive layer/elastic layer Adhesive layer/elastic layer
  • Adhesive layer/elastic layer/adhesive layer Adhesive layer/shock absorbing layer/elastic layer/adhesive layer
  • Adhesive layer/shock-absorbing layer/elastic layer/shock-absorbing layer Adhesive layer/shock-absorbing layer/elastic layer/shock-absorbing layer/adhesive layer
  • Adhesive layer/shock-absorbing layer/elastic layer/shock-absorbing layer/adhesive layer Adhesive layer/shock-absorbing layer/elastic layer/shock-absorbing layer/adhesive layer
  • g) Separator/adhesive layer/elastic layer Separator/Adhesive layer/Elastic layer/Adhesive layer/Separator
  • FIG. 2 shows an elastic sheet with an adhesive layer having the layer structure (h).
  • FIG. 3 shows an elastic sheet with an adhesive layer having the layer structure (j).
  • the total thickness of the elastic layer 2 and the adhesive layer 3 in the elastic sheet 1 is preferably 50 ⁇ m 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 ⁇ m or more, and even more preferably 70 ⁇ m or more. This sum is preferably less than or equal to 300 ⁇ m. In this case, it is possible to further reduce the thickness of the display device including the display. More preferably, the total is 200 ⁇ m or less, and even more preferably 100 ⁇ m or less.
  • the thickness of the elastic sheet 1 is preferably 50 ⁇ m or more. In this case, the strength of the elastic sheet 1 can be further improved. This thickness is more preferably 60 ⁇ m or more, and even more preferably 70 ⁇ m or more.
  • the thickness of the elastic sheet 1 is preferably 300 ⁇ m or less. In this case, it is possible to further reduce the thickness of the display device including the display. This thickness is more preferably 200 ⁇ m or less, and even more preferably 100 ⁇ m or less.
  • the elastic sheet 1 according to this embodiment can be suitably used for flexible displays.
  • the elastic sheet 1 is arranged 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. It is more preferable to be used by being directly laminated on a protective film, coating layer, or the like.
  • Materials constituting the elastic layer and the adhesive layer are as follows.
  • - Material of elastic layer Resin A Methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer.
  • a mixed resin of methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer and polymethyl methacrylate was obtained by dissolving pellets of Clarity (manufactured by Kuraray Co., Ltd.) product numbers LA4285, LA2250, and LA2270 and Dianal (manufactured by Mitsubishi Chemical Co., Ltd.) product number BR-87 in a solvent.
  • the adhesive layer 1 having the thickness shown in Table 1 was formed by applying a material for the adhesive layer (acrylic adhesive) to one surface of the elastic layer and drying it. Then, the adhesive layer having the thickness shown in Table 1 was formed by applying the acrylic adhesive to the surface of the elastic layer opposite to the adhesive layer 1 in the same manner as described above and drying it. Thus, an elastic sheet with an adhesive layer was produced.
  • Adhesive strength of the adhesive layer to the polyethylene terephthalate film was determined by attaching a polyethylene terephthalate film (thickness 25 ⁇ m, manufactured by Toyobo Co., Ltd., product number E5100) to the adhesive layer 1 of the elastic sheet with adhesive layer. Combined, a test piece with a width of 25 mm ⁇ length of 100 mm was prepared, and a method conforming to JIS-Z0237: 2009 "Adhesive tape/adhesive sheet test method" (bonding conditions: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min , peeling angle: 180°) under an environment of 23°C.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)
  • Electroluminescent Light Sources (AREA)
  • Adhesive Tapes (AREA)

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

粘着層付弾性シート及びそれを用いた可撓性ディスプレイ装置ELASTIC SHEET WITH ADHESIVE LAYER AND FLEXIBLE DISPLAY DEVICE USING SAME
　本開示は、粘着層付弾性シート及び可撓性ディスプレイ装置に関し、詳しくは、弾性体層と、粘着層とを備える粘着層付弾性シート、及びそれを用いた可撓性ディスプレイ装置に関する。 The present disclosure relates to an adhesive layer-attached elastic sheet and a flexible display device, and more specifically, to an adhesive layer-attached elastic sheet including an elastic layer and an adhesive layer, and a flexible display device using the same.
　スマートフォン、タブレット型端末、ノートパソコン等の各種電子機器に用いられる表示装置においては、ディスプレイの前面側に設けられる光学フィルム等において、外観に不具合を生じることがある。このような不具合に関し、例えば高温環境下においても、浮きや剥がれ等の発生が抑制された粘着層を形成することができる粘着剤組成物が検討されている（特許文献１参照）。 In the display devices used in various electronic devices such as smartphones, tablet terminals, and laptop computers, the optical film, etc. provided on the front side of the display may cause defects in appearance. Regarding such problems, for example, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer in which the occurrence of lifting and peeling is suppressed even in a high-temperature environment has been investigated (see Patent Document 1).
　最近では、フォルダブル端末や電子ペーパー等において、有機ＥＬ等の可撓性を有するディスプレイが用いられるようになってきている。しかし、このような可撓性ディスプレイは、屈曲半径の非常に小さい折り曲げを行う際に、折り曲げ箇所において、ディスプレイの前面側にシワが発生するという問題があった。 Recently, flexible displays such as organic EL have been used in foldable terminals and electronic paper. However, such a flexible display has a problem that when it is bent with a very small bending radius, wrinkles are generated on the front side of the display at the bending point.
特開２０１７－５７３８２号公報JP 2017-57382 A
　本開示の課題は、ディスプレイ等の屈曲半径が非常に小さい折り曲げに対して、曲げ部におけるシワの発生を抑制することができる粘着層付弾性シート、及びそれを用いた可撓性ディスプレイ装置を提供することにある。 An object of the present disclosure is to provide an adhesive layer-attached elastic sheet capable of suppressing the occurrence of wrinkles in a bent portion when a display or the like is bent with a very small bending radius, and a flexible display device using the same. to do.
　本開示の一態様に係る粘着層付弾性シートは、２０℃における引張弾性率が８０ＭＰａ以上１５００ＭＰａ未満であり、且つ８５℃における引張弾性率が４０ＭＰａ以上１０００ＭＰａ未満である弾性体層と、前記弾性体層に重なる粘着層とを備える。前記粘着層の厚みは２μｍ以上１５μｍ以下である。前記粘着層のポリエチレンテレフタレートフィルムに対する粘着力は、１０Ｎ／２５ｍｍ以上である。 An elastic sheet with an adhesive layer according to an aspect of the present disclosure includes an elastic layer having a tensile modulus of elasticity of 80 MPa or more and less than 1500 MPa at 20°C and a modulus of elasticity in tension of 40 MPa or more and less than 1000 MPa at 85°C; and an adhesive layer overlying the layers. The thickness of the adhesive layer is 2 μm or more and 15 μm or less. The adhesive layer has an adhesive strength of 10 N/25 mm or more to the polyethylene terephthalate film.
　本開示の一態様に係る可撓性ディスプレイ装置は、前記粘着層付弾性シートが可撓性を有するディスプレイの前面側に貼着されたものである。 In a flexible display device according to one aspect of the present disclosure, the elastic sheet with an adhesive layer is attached to the front side of a flexible display.
図１は、本開示の一実施形態に係る粘着層付弾性シートの概略の断面図である。FIG. 1 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to one embodiment of the present disclosure. 図２は、本開示の他の実施形態に係る粘着層付弾性シートの概略の断面図である。FIG. 2 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure. 図３は、本開示の他の実施形態に係る粘着層付弾性シートの概略の断面図である。FIG. 3 is a schematic cross-sectional view of an elastic sheet with an adhesive layer according to another embodiment of the present disclosure.
＜粘着層付弾性シート＞
　本実施形態に係る粘着層付弾性シート（以下、弾性シート１ともいう）は、２０℃における引張弾性率が８０ＭＰａ以上１５００ＭＰａ未満であり、且つ８５℃における引張弾性率が４０ＭＰａ以上１０００ＭＰａ未満である弾性体層と、前記弾性体層に重なる粘着層とを備える。前記粘着層の厚みは２μｍ以上１５μｍ以下である。前記粘着層のポリエチレンテレフタレートフィルムに対する粘着力は、１０Ｎ／２５ｍｍ以上である。 <Elastic sheet with adhesive layer>
The adhesive layer-attached elastic sheet (hereinafter also referred to as elastic sheet 1) according to the present embodiment has a tensile modulus of elasticity of 80 MPa or more and less than 1500 MPa at 20°C and a tensile modulus of elasticity of 40 MPa or more and less than 1000 MPa at 85°C. A body layer and an adhesive layer overlapping the elastic layer are provided. The thickness of the adhesive layer is 2 μm or more and 15 μm or less. The adhesive layer has an adhesive strength of 10 N/25 mm or more to the polyethylene terephthalate film.
　折り曲げ可能なディスプレイにおいて、ディスプレイの前面側（ディスプレイの表示面側）に配置されるポリエチレンテレフタレートやポリイミド等の薄膜フィルムなどが湾曲された際、引張応力と圧縮応力とが同時に集中することで、薄膜フィルム等の構造変形や剥離が起こり、シワが発生する。本発明者らは、この薄膜フィルム等の周辺に、粘着層付弾性シートを配置させ、湾曲における引張応力と圧縮応力とを緩和することにより、薄膜フィルム等の構造変形や剥離の発生を抑制し、シワの発生を抑制できることを見出した。また、本発明者らは、引張応力及び圧縮応力の緩和と、弾性シート１の弾性体層の引張弾性率との間に関連があることを見出した。すなわち、引張弾性率が２０℃において８０ＭＰａ以上１５００ＭＰａ未満であり、且つ８５℃において４０ＭＰａ以上１０００ＭＰａ未満であれば、それぞれの温度条件で、屈曲時の応力を良好に分散させることができ、湾曲部において引張応力及び圧縮応力を十分に緩和することができると考えられる。引張弾性率が２０℃及び８５℃のいずれか一方において前記範囲外であると、引張応力及び圧縮応力を十分に緩和することができない恐れがある。また、これらに加えて、弾性シート１の粘着層には、その厚みが２μｍ以上１５μｍ以下であること、及びポリエチレンテレフタレートフィルムに対する粘着力が１０Ｎ／２５ｍｍ以上であることが必要であることも見出した。粘着層の厚みが２μｍ未満であると、粘着層において剥離が発生する恐れがあり、１５μｍを超えると、柔軟な粘着層の構造変形が起こる恐れがある。粘着力が１０Ｎ／２５ｍｍ未満であると、粘着層において剥離が発生する恐れがある。弾性シート１は、これらを全て満たすことにより、例えばΦ１．５ｍｍまでの厳しい曲率半径の曲げ部におけるシワの発生を抑制できる。このように、本開示によれば、ディスプレイ等に用いることにより、屈曲半径が非常に小さい折り曲げに対して、曲げ部におけるシワの発生を抑制することができる粘着層付弾性シートを提供することができる。 In a bendable display, when a thin film such as polyethylene terephthalate or polyimide placed on the front side of the display (the display surface side of the display) is bent, the tensile stress and the compressive stress concentrate at the same time, and the thin film Structural deformation and peeling of films and the like occur, and wrinkles occur. The present inventors arranged an elastic sheet with an adhesive layer around the thin film or the like to reduce tensile stress and compressive stress in bending, thereby suppressing structural deformation and peeling of the thin film or the like. , it was found that the occurrence of wrinkles can be suppressed. The present inventors also found that there is a relationship between the relaxation of tensile stress and compressive stress and the tensile elastic 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., the stress during bending can be well dispersed under each temperature condition. It is believed that tensile stress and compressive stress can be sufficiently relieved. If the tensile elastic modulus is outside the above range at either one of 20°C and 85°C, there is a possibility that tensile stress and compressive stress cannot be sufficiently relaxed. In addition to these, the inventors have also found that the adhesive layer of the elastic sheet 1 needs to have a thickness of 2 μm or more and 15 μm or less and an adhesive force to the polyethylene terephthalate film of 10 N/25 mm or more. . If the thickness of the adhesive layer is less than 2 μm, peeling 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, the adhesive layer may peel off. By satisfying all of these, the elastic sheet 1 can suppress the generation of wrinkles at a bending portion with a severe radius of curvature up to Φ1.5 mm, for example. As described above, according to the present disclosure, it is possible to provide an adhesive layer-attached elastic sheet that can suppress the occurrence of wrinkles at the bent portion when bent with a very small bending radius by being used for a display or the like. can.
　図１に、本実施形態の弾性シートの一例を示す。図１の弾性シート１は、弾性体層２と、弾性体層２に直接重なる粘着層３とを備えている。 FIG. 1 shows an example of the elastic sheet of this embodiment. The elastic sheet 1 of FIG. 1 includes an elastic layer 2 and an adhesive layer 3 directly overlapping the elastic layer 2 .
［弾性体層］
　弾性体層２は、引張弾性率が２０℃において８０ＭＰａ以上１５００ＭＰａ未満であり、且つ８５℃において４０ＭＰａ以上１０００ＭＰａ未満である。２０℃における引張弾性率は、１００ＭＰａ以上であることが好ましく、１５０ＭＰａ以上であることがより好ましく、２００ＭＰａ以上であることがさらに好ましく、３００ＭＰａ以上であることが特に好ましい。２０℃における引張弾性率は、１４５０ＭＰａ以下であることが好ましく、１４００ＭＰａ以下であることがより好ましく、１３５０ＭＰａ以下であることがさらに好ましく、１３００ＭＰａ以下であることが特に好ましい。８５℃における引張弾性率は、７０ＭＰａ以上であることが好ましく、１００ＭＰａ以上であることがより好ましく、１５０ＭＰａ以上であることがさらに好ましい。８５℃における引張弾性率は、９００ＭＰａ以下であることが好ましく、８００ＭＰａ以下であることがより好ましく、７００ＭＰａ以下であることがさらに好ましい。引張弾性率を前記範囲とすることで、引張応力及び圧縮応力をより緩和することができ、その結果、シワの発生をより抑制することができる。 [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, still 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 higher, more preferably 100 MPa or higher, and even more preferably 150 MPa or higher. 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, the tensile stress and compressive stress can be further reduced, and as a result, the occurrence of wrinkles can be further suppressed.
　弾性シート１は、弾性体層２を１層有しても、２層以上有してもよいが、通常１層である。弾性体層２の形状は、例えばフィルム状、シート状、板状等である。 The elastic sheet 1 may have one elastic layer 2 or two or more layers, but usually has one layer. The shape of the elastic layer 2 is, for example, film-like, sheet-like, or plate-like.
　ここで、弾性体層２の引張弾性率は、動的粘弾性試験を行うことにより測定した値である。動的粘弾性試験では、弾性体層２から試験片を作製し、周波数１０Ｈｚ、昇温速度５℃／ｍｉｎの条件で、２０℃及び８５℃における引張弾性率（ＭＰａ）を測定する。引張弾性率の測定方法は、後掲の実施例の欄で説明する。 Here, the tensile elastic modulus of the elastic layer 2 is a value measured by performing a dynamic viscoelasticity test. In the dynamic viscoelasticity test, a test piece is prepared from the 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. A method for measuring the tensile modulus will be described in the Examples section below.
　弾性体層２を構成する材料の曲げ弾性率は、１００ＭＰａ以上２５００ＭＰａ以下であることが好ましい。この場合、引張応力及び圧縮応力をより緩和することができ、その結果、シワの発生をより抑制することができる。曲げ弾性率は、３００ＭＰａ以上であることがより好ましく、５００ＭＰａ以上であることがさらに好ましく、６５０ＭＰａ以上であることが特に好ましい。曲げ弾性率は、２３００ＭＰａ以下であることがより好ましく、２１００ＭＰａ以下であることがさらに好ましく、１５００ＭＰａ以下であることが特に好ましい。 The flexural modulus of the material forming 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 more relaxed, and as a result, the occurrence of wrinkles can be further suppressed. The bending elastic modulus is more preferably 300 MPa or more, further preferably 500 MPa or more, and particularly preferably 650 MPa or more. The bending elastic modulus is more preferably 2300 MPa or less, further preferably 2100 MPa or less, and particularly preferably 1500 MPa or less.
　ここで、弾性体層２を構成する材料の曲げ弾性率は、ＪＩＳ－Ｋ７１７１に準拠して、圧子半径５ｍｍ、圧縮速度２ｍｍ／ｍｉｎの条件で測定した値である。曲げ弾性率の測定方法は、後掲の実施例の欄で説明する。 Here, the flexural modulus of the material forming the elastic layer 2 is a value measured in accordance with JIS-K7171 under conditions of an indenter radius of 5 mm and a compression rate of 2 mm/min. A method for measuring the flexural modulus will be described in the Examples section below.
　弾性体層２の厚みは、３０μｍ以上であることが好ましい。この場合、応力緩和能がより向上し、シワの発生をより抑制することができる。この厚みは、４０μｍ以上であることがより好ましく、５０μｍ以上であることがさらに好ましい。弾性体層２の厚みは、２９０μｍ以下であることが好ましい。この場合、弾性シート１の薄型化をより図ることができる。この厚みは、２００μｍ以下であることがより好ましく、１００μｍ以下であることがさらに好ましい。 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 thickness of the elastic sheet 1 can be further reduced. This thickness is more preferably 200 μm or less, and even more preferably 100 μm or less.
　弾性体層２を構成する材料は、弾性体層２の引張弾性率が前記範囲であれば特に限定されず用いることができ、例えば以下のエラストマー等が挙げられる。 The material constituting the elastic layer 2 is not particularly limited as long as the elastic modulus in tension of the elastic layer 2 is within the above range, and examples thereof include the following elastomers.
　エラストマーとしては、アクリル系エラストマー、ウレタン系エラストマー、オレフィン系エラストマー、アミド系エラストマー、スチレン系エラストマー、エステル系エラストマー等が挙げられる。 Examples of elastomers include acrylic elastomers, urethane elastomers, olefin elastomers, amide elastomers, styrene elastomers, and ester elastomers.
　アクリル系エラストマーとしては、例えばハードセグメントが（メタ）アクリル酸エステル単位を含み、ソフトセグメントがアクリロニトリル単位、エチレン単位、（メタ）アクリル酸エステル単位等を含む共重合体などが挙げられる。なお、（メタ）アクリル酸エステル単位は、アクリル酸エステル単位及びメタクリル酸エステル単位の両方を含む。 Examples of acrylic elastomers include copolymers in which the hard segment contains (meth)acrylic acid ester units and the soft segment contains acrylonitrile units, ethylene units, (meth)acrylic acid ester units, and the like. In addition, the (meth)acrylic acid ester unit includes both an acrylic acid ester unit and a methacrylic acid ester unit.
　ウレタン系エラストマーとしては、例えばハードセグメントがポリウレタン構造を含み、ソフトセグメントがポリエステル構造、ポリエーテル構造、ポリカプロラクトン構造等を含む共重合体などが挙げられる。 Examples of urethane-based elastomers include copolymers in which the hard segment includes a polyurethane structure and the soft segment includes a polyester structure, polyether structure, polycaprolactone structure, or the like.
　オレフィン系エラストマーとしては、例えばポリプロピレン、ポリエチレン等のオレフィン系樹脂のマトリックスに、例えばエチレン・プロピレンゴム、エチレン・プロピレン・ジエン三元共重合体等のオレフィン系ゴムを微分散させたポリマーアロイ；ハードセグメントがポリブタジエン構造を含み、ソフトセグメントがポリエーテル構造、ポリエステル構造等を含む共重合体などが挙げられる。 As the olefinic elastomer, for example, a polymer alloy obtained by finely dispersing an olefinic rubber such as an ethylene/propylene rubber or an ethylene/propylene/diene terpolymer in a matrix of an olefinic resin such as polypropylene or polyethylene; contains a polybutadiene structure, and the soft segment contains a polyether structure, a polyester structure, or the like.
　アミド系エラストマーとしては、例えばハードセグメントがポリアミド構造を含み、ソフトセグメントがポリエーテル構造、ポリエステル構造等を含む共重合体などが挙げられる。 Examples of amide-based elastomers include copolymers in which the hard segment contains a polyamide structure and the soft segment contains a polyether structure, polyester structure, or the like.
　スチレン系エラストマーとしては、例えばハードセグメントがスチレン単位を含み、ソフトセグメントがブタジエン単位若しくは水添ブタジエン単位、又はイソプレン単位若しくは水添イソプレン単位等を含む共重合体などが挙げられる。 Examples of styrene-based 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.
　エステル系エラストマーとしては、例えばハードセグメントがポリエステル構造を含み、ソフトセグメントがポリエーテル構造、ポリエステル構造等を含む共重合体などが挙げられる。 Examples of ester-based elastomers include copolymers in which the hard segment contains a polyester structure and the soft segment contains a polyether structure, polyester structure, or the like.
　弾性体層２を構成する材料は、エラストマーを含むことが好ましく、粘着性、透明性及び耐候性の観点から、アクリル系エラストマーを含むことが好ましい。 The material constituting the elastic layer 2 preferably contains an elastomer, and preferably contains an acrylic elastomer from the viewpoint of adhesiveness, transparency and weather resistance.
　アクリル系エラストマーの（メタ）アクリル酸エステル単位としては、例えばメチル（メタ）アクリレート単位；エチル（メタ）アクリレート単位；ｎ－プロピル（メタ）アクリレート単位、ｉｓｏ－プロピル（メタ）アクリレート単位等のプロピル（メタ）アクリレート単位；ｎ－ブチル（メタ）アクリレート単位、ｉｓｏ－ブチル（メタ）アクリレート単位、ｓｅｃ－ブチル（メタ）アクリレート単位、ｔｅｒｔ－ブチル（メタ）アクリレート単位等のブチル（メタ）アクリレート単位；ペンチル（メタ）アクリレート単位；ヘキシル（メタ）アクリレート単位；シクロヘキシル（メタ）アクリレート単位；へプチル（メタ）アクリレート単位；ｎ－オクチル（メタ）アクリレート単位、２－エチルヘキシル（メタ）アクリレート単位等のオクチル（メタ）アクリレート単位；ノニル（メタ）アクリレート単位；デシル（メタ）アクリレート単位；ウンデシル（メタ）アクリレート単位；ドデシル（メタ）アクリレート単位；トリデシル（メタ）アクリレート単位；テトラデシル（メタ）アクリレート単位；ヘキサデシル（メタ）アクリレート単位；オクタデシル（メタ）アクリレート単位；イコシル（メタ）アクリレート単位等のアルキル（メタ）アクリレートなどが挙げられる。 Examples of the (meth)acrylic acid ester units of the acrylic elastomer include methyl (meth)acrylate units; ethyl (meth)acrylate units; n-propyl (meth)acrylate units, iso-propyl (meth)acrylate units and other 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, tert-butyl (meth)acrylate units; pentyl (Meth) acrylate units; hexyl (meth) acrylate units; cyclohexyl (meth) acrylate units; heptyl (meth) acrylate units; ) acrylate unit; nonyl (meth) acrylate unit; decyl (meth) acrylate unit; undecyl (meth) acrylate unit; dodecyl (meth) acrylate unit; tridecyl (meth) acrylate unit; Acrylate units; octadecyl (meth)acrylate units; and alkyl (meth)acrylates such as icosyl (meth)acrylate units.
　アクリル系エラストマーは、（メタ）アクリル酸エステル単位以外に、他の単量体に由来する単位を有していてもよい。他の単量体としては、例えば２－ヒドロキシエチル（メタ）アクリレート等のヒドロキシアルキル（メタ）アクリレート；グリセリンジ（メタ）アクリレート、グリシジル（メタ）アクリレート、２－（メタ）アクリロイルオキシエチルイソシアネート、（メタ）アクリル酸、イタコン酸、無水マレイン酸、クロトン酸、マレイン酸、フマル酸などが挙げられる。 The acrylic elastomer may have units derived from other monomers in addition to the (meth)acrylic acid ester units. Other monomers include, for example, 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, fumaric acid and the like.
　アクリル系エラストマーのハードセグメントを与える単量体は、ホモポリマーのガラス転移温度（Ｔｇ）が６０℃以上であることが好ましい。アクリル系エラストマーのソフトセグメントを与える単量体は、ホモポリマーのＴｇが－１０℃以下であることが好ましい。ホモポリマーのＴｇが６０℃以上である単量体としては、例えばメチルメタクリレート、シクロヘキシルメタクリレート、イソボルニルメタクリレート等が挙げられる。ホモポリマーのＴｇが－１０℃以下である単量体としては、例えばｎ－ブチルアクリレート、２－エチルヘキシルアクリレート、イソオクチルアクリレート、ｎ－オクチルアクリレート、イソノニルアクリレート、ラウリルメタクリレート等が挙げられる。 The monomer that provides the hard segment of the acrylic elastomer preferably has a homopolymer glass transition temperature (Tg) of 60°C or higher. The monomer that provides the soft segment of the acrylic elastomer preferably has a homopolymer Tg of -10°C or lower. Monomers whose homopolymer Tg is 60° C. or higher include, for example, methyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate. Monomers whose homopolymer Tg is -10° C. or less include, for example, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-octyl acrylate, isononyl acrylate, lauryl methacrylate and the like.
　アクリル系エラストマーの全単位に対するハードセグメントを構成する単位の割合は、５質量％以上であることが好ましく、２０質量％以上であることがより好ましく、４０質量％以上であることがさらに好ましく、５０質量％以上であることが特に好ましい。この割合は、９５質量％以下であることが好ましく、９０質量％以下であることがより好ましく、８０質量％以下であることがさらに好ましく、７５質量％以下であることが特に好ましい。ハードセグメントの割合を前記範囲とすることで、弾性層の引張弾性率をより適度なものに調整することができ、その結果、シワの発生をより抑制することができる。 The ratio of the 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, further preferably 40% by mass or more, and 50% by mass or more. % by mass or more is particularly preferred. This proportion 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 proportion of the hard segment within the above range, the tensile modulus of elasticity of the elastic layer can be adjusted to a more moderate one, and as a result, the occurrence of wrinkles can be further suppressed.
　アクリル系エラストマーは、粘着性、透明性及び耐候性により優れる観点から、ブチルアクリレート単位と、メチルメタクリレート単位とを有する樹脂を含むことが好ましく、ソフトセグメントがブチルアクリレート単位を含み、ハードセグメントがメチルメタクリレート単位を含むブロック共重合体を含むことがより好ましく、メチルメタクリレートブロック－ブチルアクリレートブロック－メチルメタクリレートブロックで構成されるトリブロック共重合体を含むことがさらに好ましい。前記樹脂の全単位に対するブチルアクリレート単位の割合は、１０質量％以上６０質量％以下であることが好ましく、２５質量％以上５０質量％以下であることがより好ましい。前記樹脂の全単位に対するメチルメタクリレート単位の割合は、４０質量％以上９０質量％以下であることが好ましく、５０質量％以上７５質量％以下であることがより好ましい。 The acrylic elastomer preferably contains a resin having a butyl acrylate unit and a methyl methacrylate unit from the viewpoint of superior adhesiveness, transparency, and weather resistance, the soft segment containing the butyl acrylate unit, and the hard segment containing methyl methacrylate. It more preferably contains a block copolymer containing units, and more preferably contains a triblock copolymer composed of a methyl methacrylate block-butyl acrylate block-methyl methacrylate block. The ratio of butyl acrylate units to all units of the resin is preferably 10% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less. The ratio of methyl methacrylate units to all units of the resin is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 75% by mass or less.
　アクリル系エラストマーの市販品としては、例えばクラレ社製のクラリティＬＡ４２８６、ＬＡ２２５０、ＬＡ２２７０等が挙げられる。 Commercially available acrylic elastomers include Clarity LA4286, LA2250 and LA2270 manufactured by Kuraray Co., Ltd., for example.
　弾性体層２の形成方法は、特に限定されないが、例えば弾性体層２を構成する材料を溶媒に溶解させて塗布し乾燥させてキャストフィルムを得る方法、弾性体層２を構成する材料をＴダイ法やインフレーション成膜法等により成形してフィルムを得る方法などが挙げられる。 The method of forming the elastic layer 2 is not particularly limited. Examples include a method of obtaining a film by molding by a die method, an inflation film forming method, or the like.
［粘着層］
　粘着層３は、弾性体層２に重ねて配置される。弾性シート１は、粘着層３を１層備えてもよく、２層備えてもよく、３層以上備えてもよい。 [Adhesive layer]
The adhesive layer 3 is placed over the elastic layer 2 . The elastic sheet 1 may have one adhesive layer 3, two layers, or three or more layers.
　粘着層３の形状は、例えばフィルム状、シート状、板状等である。 The shape of the adhesive layer 3 is, for example, film-like, sheet-like, or plate-like.
　粘着層３の厚みは、２μｍ以上１５μｍ以下である。粘着層３の厚みは、４μｍ以上であることが好ましく、６μｍ以上であることがより好ましく、８μｍ以上であることがさらに好ましく、９μｍ以上であることが特に好ましい。この場合、弾性シート１の応力緩和能がより向上し、その結果、シワの発生をより抑制することができる。粘着層３の厚みは、１２μｍ以下であることが好ましく、１０μｍ以下であることがより好ましい。この粘着層３の厚みは、粘着層１層の厚みをいう。 The thickness of the adhesive layer 3 is 2 μm or more and 15 μm or less. The thickness of the adhesive layer 3 is preferably 4 µm or more, more preferably 6 µm or more, still 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. The thickness of the adhesive layer 3 is preferably 12 μm or less, more preferably 10 μm or less. The thickness of the adhesive layer 3 refers to the thickness of one adhesive layer.
　粘着層３のポリエチレンテレフタレートフィルムに対する粘着力は、１０Ｎ／２５ｍｍ以上である。粘着力は１２Ｎ／２５ｍｍ以上であることが好ましく、１４Ｎ／２５ｍｍ以上であることがより好ましく、１５Ｎ／２５ｍｍ以上であることがさらに好ましい。この場合、シワの発生をより抑制することができる。 The adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film is 10 N/25 mm or more. The adhesive strength is preferably 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.
　粘着層３は、例えば粘着剤から形成することができる。この粘着剤は、粘着層３のポリエチレンテレフタレートフィルムに対する粘着力を前記範囲とすることができるものであれば特に限定されず用いることができる。 The adhesive layer 3 can be formed, for example, from an adhesive. Any adhesive can be used without particular limitation as long as the adhesive strength of the adhesive layer 3 to the polyethylene terephthalate film can be within the above range.
　粘着剤としては、例えばアクリル系粘着剤、ウレタン系粘着剤、ポリエステル粘着剤等が挙げられる。粘着剤は、粘着力をより大きくできる観点から、アクリル系粘着剤を含むことが好ましい。 Examples of adhesives include acrylic adhesives, urethane adhesives, and polyester adhesives. The adhesive preferably contains an acrylic adhesive from the viewpoint of increasing the adhesive strength.
　アクリル系粘着剤としては、例えばメチル（メタ）アクリレート；エチル（メタ）アクリレート；ｎ－ブチル（メタ）アクリレート、ｉｓｏ－ブチル（メタ）アクリレート等のブチル（メタ）アクリレート；２－エチルヘキシル（メタ）アクリレート；ドデシル（メタ）アクリレート；オクタデシル（メタ）アクリレートなどのアルキル（メタ）アクリレート；２－ヒドロキシエチル（メタ）アクリレート等のヒドロキシアルキル（メタ）アクリレート；メトキシエチル（メタ）アクリレート、ブトキシメチル（メタ）アクリレート等のアルコキシアルキル（メタ）アクリレート；シクロヘキシル（メタ）アクリレート、フェニル（メタ）アクリレート、ベンジル（メタ）アクリレート、ビニルアセテート；（メタ）アクリルアミド、Ｎ－メチロール（メタ）アクリルアミド等の（メタ）アクリルアミド；スチレン、アクリロニトリル、ビニルピリジン、ビニルピロリドン、ビニルアルキルエーテルなどの単量体の単独重合体又は共重合体などが挙げられる。 Examples of acrylic adhesives include methyl (meth) acrylate; ethyl (meth) acrylate; butyl (meth) acrylate such as n-butyl (meth) acrylate and iso-butyl (meth) acrylate; 2-ethylhexyl (meth) acrylate. dodecyl (meth)acrylate; alkyl (meth)acrylates such as octadecyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; methoxyethyl (meth)acrylate, butoxymethyl (meth)acrylate alkoxyalkyl (meth)acrylates such as; cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, vinyl acetate; (meth)acrylamides such as (meth)acrylamide and N-methylol (meth)acrylamide; styrene , acrylonitrile, vinylpyridine, vinylpyrrolidone, vinylalkyl ether, and the like.
　粘着層３の形成方法は、特に限定されないが、例えば弾性体層２の面に粘着剤を塗布して形成する方法、弾性体層２を構成する材料と粘着剤とを共押出することにより形成する方法などが挙げられる。 The method of forming the adhesive layer 3 is not particularly limited, but for example, a method of applying an adhesive to the surface of the elastic layer 2 to form it, or a method of co-extrusion of the material constituting the elastic layer 2 and an adhesive. and methods to do so.
［他の層］
　弾性シート１は、弾性体層２及び粘着層３以外に、他の層を備えてもよい。弾性シート１は、他の層を１層又は２層以上備えてもよい。他の層の形状は、例えばフィルム状、シート状、板状等である。 [Other layers]
The elastic sheet 1 may include other layers in addition to the elastic layer 2 and the adhesive layer 3 . The elastic sheet 1 may comprise one or more other layers. The shape of other layers is, for example, film-like, sheet-like, or plate-like.
　弾性シート１は、他の層として、例えば弾性体層２と粘着層３との間に、衝撃や振動を吸収するための衝撃吸収層５を備えてもよい。また、弾性シート１は、他の層として、粘着層３の弾性体層２とは反対側に、セパレーター等の保護層などを備えてもよい。 The elastic sheet 1 may include, as another layer, a shock absorbing layer 5 for absorbing shock and vibration between the elastic layer 2 and the adhesive layer 3, for example. The elastic sheet 1 may also include a protective layer such as a separator on the side of the adhesive layer 3 opposite to the elastic layer 2 as another layer.
［層構成］
　本実施形態に係る粘着層付弾性シートの層構成としては、例えば下記（ａ）～（ｌ）等が挙げられる。以下において、Ａ／Ｂ／Ｃの表記は、例えば表示装置の最前面から、Ａ、Ｂ、Ｃの順に積層していることを示す。
（ａ）粘着層／弾性体層
（ｂ）粘着層／弾性体層／粘着層
（ｃ）粘着層／衝撃吸収層／弾性体層
（ｄ）粘着層／衝撃吸収層／弾性体層／粘着層
（ｅ）粘着層／衝撃吸収層／弾性体層／衝撃吸収層
（ｆ）粘着層／衝撃吸収層／弾性体層／衝撃吸収層／粘着層
（ｇ）セパレーター／粘着層／弾性体層
（ｈ）セパレーター／粘着層／弾性体層／粘着層／セパレーター
（ｉ）セパレーター／粘着層／衝撃吸収層／弾性体層
（ｊ）セパレーター／粘着層／衝撃吸収層／弾性体層／粘着層／セパレーター
（ｋ）セパレーター／粘着層／衝撃吸収層／弾性体層／衝撃吸収層
（ｌ）セパレーター／粘着層／衝撃吸収層／弾性体層／衝撃吸収層／粘着層／セパレーター [Layer structure]
Examples of the layer structure of the adhesive layer-attached elastic sheet according to the present embodiment include the following (a) to (l). In the following, the notation of A/B/C indicates that layers are laminated in order of A, B, and C from the front surface of the display device, for example.
(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/Impact absorption layer/Elastic layer/Impact absorption layer (l) Separator/Adhesive layer/Impact absorption layer/Elastic layer/Impact absorption layer/Adhesive layer/Separator
　図２は、前記（ｈ）の層構成を有する粘着層付弾性シートを示す。図２の弾性シート１は、弾性体層２と、弾性体層２の両面に直接積層される２つの粘着層３，３と、これらの粘着層３，３に直接積層される２つのセパレーター４，４とを備えている。 FIG. 2 shows an elastic sheet with an adhesive layer having the layer structure (h). Elastic sheet 1 in FIG. , 4.
　図３は、前記（ｊ）の層構成を有する粘着層付弾性シートを示す。図３の弾性シート１は、弾性体層２と、弾性体層２の一方の面に直接積層される衝撃吸収層５と、弾性体層２の一方の面及び衝撃吸収層５の一方の面に直接積層される２つの粘着層３，３と、これらの粘着層３，３に直接積層される２つのセパレーター４，４とを備えている。 FIG. 3 shows an elastic sheet with an adhesive layer having the layer structure (j). The elastic sheet 1 shown in FIG. and two separators 4, 4 directly laminated on the adhesive layers 3, 3.
　弾性シート１における弾性体層２の厚み及び粘着層３の厚みの総計は、５０μｍ以上であることが好ましい。この場合、弾性シート１の応力緩和能をより向上させることができ、その結果、シワの発生をより抑制することができる。この厚みは、６０μｍ以上であることがより好ましく、７０μｍ以上であることがさらに好ましい。この総計は、３００μｍ以下であることが好ましい。この場合、ディスプレイを含む表示装置の薄型化をより図ることができる。この総計は、２００μｍ以下であることがより好ましく、１００μｍ以下であることがさらに好ましい。 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. This sum is preferably less than or equal to 300 μm. In this case, it is possible to further reduce the thickness of the display device including the display. More preferably, the total is 200 μm or less, and even more preferably 100 μm or less.
　弾性シート１の厚みは、５０μｍ以上であることが好ましい。この場合、弾性シート１の強度をより向上させることができる。この厚みは、６０μｍ以上であることがより好ましく、７０μｍ以上であることがさらに好ましい。弾性シート１の厚みは、３００μｍ以下であることが好ましい。この場合、ディスプレイを含む表示装置の薄型化をより図ることができる。この厚みは、２００μｍ以下であることがより好ましく、１００μｍ以下であることがさらに好ましい。 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, it is possible to further reduce the thickness of the display device including the display. This thickness is more preferably 200 μm or less, and even more preferably 100 μm or less.
　本実施形態に係る弾性シート１は、可撓性ディスプレイ用に好適に用いることができる。弾性シート１は、可撓性ディスプレイの前面側に配置され、すなわち、可撓性ディスプレイの前面側に貼着されて用いられることが好ましく、表示装置の最前面に配置されるポリエチレンテレフタレート、ポリイミド等の保護フィルム、コーティング層などに直接積層されて用いられることがより好ましい。本実施形態に係る弾性シート１を、可撓性ディスプレイを含む表示装置のディスプレイの前面側に配置することにより、表示装置の屈曲半径が非常に小さい折り曲げに対して、曲げ部におけるシワの発生が抑制された可撓性ディスプレイ装置を提供することができる。 The elastic sheet 1 according to this embodiment can be suitably used for flexible displays. The elastic sheet 1 is arranged 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. It is more preferable to be used by being directly laminated on a protective film, coating layer, or the like. By arranging the elastic sheet 1 according to the present embodiment on the front side of the display of a display device including a flexible display, wrinkles are not generated at the bent portion when the display device is bent with a very small bending radius. A constrained flexible display device can be provided.
　以下、本開示を実施例によってさらに詳しく説明するが、本開示はこれらの実施例に何ら限定されるものではない。 The present disclosure will be described in more detail below with reference to Examples, but the present disclosure is not limited to these Examples.
１．粘着層付弾性シートの作製
　弾性体層及び粘着層を構成する材料は下記の通りである。
－弾性体層の材料
・樹脂Ａ：メチルメタクリレート－ｎ－ブチルアクリレート－メチルメタクリレート・トリブロック共重合体。または、メチルメタクリレート－ｎ－ブチルアクリレート－メチルメタクリレート・トリブロック共重合体とポリメチルメタクリレートの混合樹脂。
　各実施例で用いる樹脂Ａの溶液は、クラリティ（クラレ社製）の品番ＬＡ４２８５、ＬＡ２２５０、ＬＡ２２７０及びダイヤナール(三菱ケミカル社製)の品番ＢＲ－８７のペレットをそれぞれ溶媒に溶解させ、得られた各溶媒のうちの２種を、表１に示すＢＡ単位（ｎ－ブチルアクリレート単位）及びＭＭＡ単位（メチルメタクリレート単位）の各割合（質量％）となるように混合して調製した。
－粘着層の材料
・アクリル系粘着剤。綜研化学製。品名ＳＫダイン。品番ＳＫ１７１７ＤＴ。２－エチルヘキシルアクリレート、ブチルアクリレート及び２－ヒドロキシエチルアクリレート含有。 1. Preparation of Elastic Sheet with Adhesive Layer Materials constituting the elastic layer and the adhesive layer are as follows.
- Material of elastic layer Resin A: Methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer. Alternatively, a mixed resin of methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer and polymethyl methacrylate.
The resin A solution used in each example was obtained by dissolving pellets of Clarity (manufactured by Kuraray Co., Ltd.) product numbers LA4285, LA2250, and LA2270 and Dianal (manufactured by Mitsubishi Chemical Co., Ltd.) product number BR-87 in a solvent. Two kinds of each solvent were mixed and prepared so that each ratio (% by mass) of BA units (n-butyl acrylate units) and MMA units (methyl methacrylate units) shown in Table 1 was obtained.
- Adhesive layer material/acrylic adhesive. Manufactured by Soken Chemical. Product name: SK dyne. Product number SK1717DT. Contains 2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate.
　前記調製した弾性体層の材料（樹脂Ａ）の溶液を塗布し乾燥させることで、表１に示す弾性体層の厚みのキャストフィルムを作製し、弾性体層を得た。次に、この弾性体層の一方の面に、粘着層の材料（アクリル系粘着剤）を塗布し乾燥させることで、表１に示す厚みの粘着層１を形成した。次いで、弾性体層の粘着層１とは反対側の面に、前記同様に、前記アクリル系粘着剤を塗布し乾燥させることで、表１に示す厚みの粘着層を形成した。このようにして、粘着層付弾性シートを作製した。 By coating and drying the solution of the material (resin A) for the elastic layer prepared above, a cast film having the thickness of the elastic layer shown in Table 1 was produced to obtain the elastic layer. Next, the adhesive layer 1 having the thickness shown in Table 1 was formed by applying a material for the adhesive layer (acrylic adhesive) to one surface of the elastic layer and drying it. Then, the adhesive layer having the thickness shown in Table 1 was formed by applying the acrylic adhesive to the surface of the elastic layer opposite to the adhesive layer 1 in the same manner as described above and drying it. Thus, an elastic sheet with an adhesive layer was produced.
２．評価
（１）弾性体層の引張弾性率
　粘着層付弾性シートから弾性体層を得、この弾性体層から、幅１０ｍｍ、長さ２０ｍｍの試験片を作製した。この試験片について、動的粘弾性測定装置（アイティー計測制御社製、ＤＶＡ－２００）を用い、周波数１０Ｈｚ、昇温速度５℃／分の条件で、２０℃及び８５℃における引張弾性率（ＭＰａ）を測定した。 2. Evaluation (1) Tensile Modulus of Elastic Layer An elastic layer was obtained from the adhesive layer-attached elastic sheet, and a test piece having a width of 10 mm and a length of 20 mm was produced from the elastic layer. For this test piece, using a dynamic viscoelasticity measuring device (DVA-200, manufactured by IT Keisoku Co., Ltd.), under the conditions of a frequency of 10 Hz and a heating rate of 5 ° C./min, the tensile modulus at 20 ° C. and 85 ° C. ( MPa) was measured.
（２）弾性体層を構成する材料の曲げ弾性率
　粘着層付弾性シートから弾性体層を得、この弾性体層から、幅１０ｍｍ、長さ８０ｍｍの試験片を作製した。この試験片について、ＪＩＳ－Ｋ７１７１（プラスチック－曲げ特性の求め方）に準拠し、圧子半径５ｍｍ、圧縮速度２ｍｍ／ｍｉｎの条件で、２３℃における曲げ弾性率（ＭＰａ）を測定した。 (2) Flexural Elastic Modulus of Material Constituting Elastic Layer An elastic layer was obtained from the adhesive layer-attached elastic sheet, and a test piece having a width of 10 mm and a length of 80 mm was produced from the elastic layer. For this test piece, the flexural modulus (MPa) at 23° C. was measured under conditions of an indenter radius of 5 mm and a compression rate of 2 mm/min in accordance with JIS-K7171 (Plastics—Determination of flexural properties).
（３）粘着層のポリエチレンテレフタレートフィルムに対する粘着力
　粘着層のポリエチレンテレフタレートフィルムに対する粘着力は、粘着層付弾性シートにおける粘着層１に、ポリエチレンテレフタレートフィルム（厚み２５μｍ、東洋紡社製、品番Ｅ５１００）を貼合し、幅２５ｍｍ×長さ１００ｍｍの試験片を作製し、ＪＩＳ－Ｚ０２３７：２００９「粘着テープ・粘着シート試験方法」に準拠した方法（貼り合わせ条件：２ｋｇローラー１往復、剥離速度：３００ｍｍ／ｍｉｎ、剥離角度：１８０°）に準拠した方法により、２３℃の環境下で測定した。 (3) Adhesive strength of the adhesive layer to the polyethylene terephthalate film The adhesive strength of the adhesive layer to the polyethylene terephthalate film was determined by attaching a polyethylene terephthalate film (thickness 25 μm, manufactured by Toyobo Co., Ltd., product number E5100) to the adhesive layer 1 of the elastic sheet with adhesive layer. Combined, a test piece with a width of 25 mm × length of 100 mm was prepared, and a method conforming to JIS-Z0237: 2009 "Adhesive tape/adhesive sheet test method" (bonding conditions: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min , peeling angle: 180°) under an environment of 23°C.
（４）屈曲試験
　粘着層付弾性シートの両面に、ポリエチレンテレフタレートフィルム（厚み２５μｍ、東洋紡社製、品番Ｅ５１００）を貼合して、幅２０ｍｍ、長さ１５０ｍｍの屈曲試験用サンプルを作製した。この屈曲試験用サンプルについて、屈曲試験装置（ユアサ社製）を用いて、屈曲試験を行った。屈曲試験条件は、曲率半径Ｒ＝２．５ｍｍ、屈曲速度９０回／分とし、屈曲回数を１万回とした。屈曲試験後のサンプルを、目視で観察し、シワの発生の有無を調べた。シワが発生していない場合は「ＯＫ」と、シワが発生した場合は「ＮＧ」と評価した。 (4) Bending Test A polyethylene terephthalate film (thickness: 25 μm, manufactured by Toyobo Co., Ltd., product number E5100) was laminated on both sides of the adhesive layer-attached elastic sheet to prepare a bending test sample with a width of 20 mm and a length of 150 mm. A bending test was performed on this bending test sample using a bending tester (manufactured by Yuasa Corporation). The bending test conditions were a radius of curvature R of 2.5 mm, a bending rate of 90 times/minute, and a number of times of bending of 10,000 times. After the bending test, the samples were visually observed to check for wrinkles. When wrinkles were not generated, it was evaluated as "OK", and when wrinkles were generated, it was evaluated as "NG".
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　１　粘着層付弾性シート
　２　弾性体層
　３　粘着層
　４　セパレーター
　５　衝撃吸収層 REFERENCE SIGNS LIST 1 elastic sheet with adhesive layer 2 elastic layer 3 adhesive layer 4 separator 5 impact absorption layer

Claims (6)

  1. 　２０℃における引張弾性率が８０ＭＰａ以上１５００ＭＰａ未満であり、且つ８５℃における引張弾性率が４０ＭＰａ以上１０００ＭＰａ未満である弾性体層と、
    　前記弾性体層に重なる粘着層と
    　を備え、
    　前記粘着層の厚みが２μｍ以上１５μｍ以下であり、
    　前記粘着層のポリエチレンテレフタレートフィルムに対する粘着力が、１０Ｎ／２５ｍｍ以上である粘着層付弾性シート。     an elastic layer having a tensile modulus of elasticity of 80 MPa or more and less than 1500 MPa at 20° C. and a tensile modulus of elasticity of 40 MPa or more and less than 1000 MPa at 85° C.;
    and an adhesive layer overlapping the elastic layer,
    The adhesive layer has a thickness of 2 μm or more and 15 μm or less,
    The adhesive layer-attached elastic sheet, wherein the adhesive layer has an adhesive strength of 10 N/25 mm or more to the polyethylene terephthalate film.
  2. 　前記弾性体層の厚みが５０μｍ以上２９０μｍ以下である請求項１に記載の粘着層付弾性シート。 The elastic sheet with an adhesive layer according to claim 1, wherein the elastic layer has a thickness of 50 µm or more and 290 µm or less.
  3. 　前記弾性体層の厚み及び前記粘着層の厚みの総計が５０μｍ以上３００μｍ以下である請求項１又は２に記載の粘着層付弾性シート。 The elastic sheet with an 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. 　前記弾性体層が、ブチルアクリレート単位と、メチルメタクリレート単位とを有する樹脂を含む請求項１から３のいずれか一項に記載の粘着層付弾性シート。 The adhesive layer-attached elastic sheet according to any one of claims 1 to 3, wherein the elastic layer contains a resin having butyl acrylate units and methyl methacrylate units.
  5. 　可撓性ディスプレイ用である請求項１から４のいずれか一項に記載の粘着層付弾性シート。 The elastic sheet with an adhesive layer according to any one of claims 1 to 4, which is for flexible displays.
  6. 　請求項１から４のいずれか一項に記載の粘着層付弾性シートが可撓性を有するディスプレイの前面側に貼着された可撓性ディスプレイ装置。 A flexible display device in which the adhesive layer-attached elastic sheet according to any one of claims 1 to 4 is attached to the front side of a flexible display.
PCT/JP2022/007470 2021-02-25 2022-02-24 Adhesive-layer-equipped elastic sheet, and flexible display device in which same is used WO2022181656A1 (en)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
JP2014115468A (en) * 2012-12-10 2014-06-26 Nitto Denko Corp Optical film having adhesive agent on both sides, and manufacturing method of image display unit using the same
JP2015178575A (en) * 2014-03-19 2015-10-08 リンテック株式会社 Substrate-less double-sided adhesive tape and method of producing the same
JP2018028087A (en) * 2013-06-19 2018-02-22 エルジー・ケム・リミテッド Pressure-sensitive adhesive composition
JP2018524425A (en) * 2015-06-03 2018-08-30 スリーエム イノベイティブ プロパティズ カンパニー Acrylic block copolymer-based assembly layer for flexible displays
JP2021138934A (en) * 2020-02-28 2021-09-16 日東電工株式会社 Adhesive sheet and use thereof

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JP6725373B2 (en) 2015-09-16 2020-07-15 日東電工株式会社 Adhesive composition, adhesive layer, optical film with adhesive layer, optical member, and image display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014115468A (en) * 2012-12-10 2014-06-26 Nitto Denko Corp Optical film having adhesive agent on both sides, and manufacturing method of image display unit using the same
JP2018028087A (en) * 2013-06-19 2018-02-22 エルジー・ケム・リミテッド Pressure-sensitive adhesive composition
JP2015178575A (en) * 2014-03-19 2015-10-08 リンテック株式会社 Substrate-less double-sided adhesive tape and method of producing the same
JP2018524425A (en) * 2015-06-03 2018-08-30 スリーエム イノベイティブ プロパティズ カンパニー Acrylic block copolymer-based assembly layer for flexible displays
JP2021138934A (en) * 2020-02-28 2021-09-16 日東電工株式会社 Adhesive sheet and use thereof

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