WO2023276654A1 - Optical film with cover film - Google Patents

Optical film with cover film Download PDF

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Publication number
WO2023276654A1
WO2023276654A1 PCT/JP2022/023779 JP2022023779W WO2023276654A1 WO 2023276654 A1 WO2023276654 A1 WO 2023276654A1 JP 2022023779 W JP2022023779 W JP 2022023779W WO 2023276654 A1 WO2023276654 A1 WO 2023276654A1
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WO
WIPO (PCT)
Prior art keywords
film
adhesive layer
cover film
less
pressure
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PCT/JP2022/023779
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French (fr)
Japanese (ja)
Inventor
大生 三浦
美菜子 野田
翔 寳田
Original Assignee
日東電工株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to KR1020237044074A priority Critical patent/KR20240027606A/en
Priority to CN202280046835.3A priority patent/CN117580709A/en
Publication of WO2023276654A1 publication Critical patent/WO2023276654A1/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
    • 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
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • 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
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material 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
    • 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
    • B32B7/023—Optical 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
    • 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]
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering

Definitions

  • the present invention relates to an optical film with a cover film.
  • a display panel has a laminated structure including, for example, a pixel panel, a touch panel, and a transparent cover film.
  • An optical film having a predetermined optical function is provided in the laminated structure of the display panel.
  • optical films include film-like polarizing films and retardation films.
  • the optical film is produced, for example, as an optical film with an adhesive layer in which an adhesive layer is provided on each of both surfaces of the optical film.
  • the optical film with a pressure-sensitive adhesive layer is manufactured as an optical film with a cover film in which the pressure-sensitive adhesive layer is covered with a cover film, for example.
  • Such an optical film with a cover film is described, for example, in Patent Document 1 below.
  • Foldable display panels require that each element in the laminate structure be thin and flexible.
  • Optical films for foldable display panels are also required to be thin and flexible.
  • the thinner the optical film with an adhesive layer the more the load for starting peeling when one cover film is peeled from the adhesive layer at the end of the optical film. It tends to cause significant deformation of the optical film. Therefore, when one cover film is peeled off, the other cover film is likely to be peeled off. In addition, cracks are likely to occur at the edges of the optical film when one of the cover films is peeled off.
  • optical films with pressure-sensitive adhesive layers for foldable display panels are required to exhibit sufficient adhesion reliability of the pressure-sensitive adhesive layer to the optical film even when folded.
  • the pressure-sensitive adhesive layer tends to peel off from the optical film at the bending portion of the device. This is because when the device is folded, stress such as shear stress locally acts on the pressure-sensitive adhesive layer at the folded portion. Occurrence of the peeling causes malfunction of the device and is not preferable.
  • the present invention is suitable for peeling one cover film from a thin optical film with an adhesive layer while suppressing peeling of the other cover film and cracking at the edge of the optical film, and is suitable for peeling the optical film during bending.
  • the present invention [1] provides a cover film-attached optical film comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction.
  • the second pressure-sensitive adhesive layer has a third thickness of 5 ⁇ m or more and 100 ⁇ m or less, and the second pressure-sensitive adhesive layer has a thickness of 20 kPa or more and 100 kPa at 25 ° C. having the following second shear storage modulus, the first cover film having a fourth thickness of 40 ⁇ m or more and 80 ⁇ m or less, the second cover film having a fifth thickness of 40 ⁇ m or more and 80 ⁇ m or less, The ratio of the fourth thickness to the fifth thickness is 1 or less, and the second cover film has a first peel force for peeling the first cover film from the first pressure-sensitive adhesive layer. It includes an optical film with a cover film, wherein the ratio to the second peeling force for peeling from the two pressure-sensitive adhesive layers is 0.9 or less, and the first peeling force is 10 gf/25 mm or less.
  • the present invention [2] includes the optical film with a cover film according to [1] above, wherein the ratio of the third thickness to the third thickness is 0.1 or more and 2 or less.
  • the present invention [3] includes the optical film with a cover film according to [1] or [2] above, wherein the ratio of the first shear storage modulus to the second shear storage modulus is 0.5 or more. .
  • the present invention [4] is an optical film with a cover film, comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction.
  • the second pressure-sensitive adhesive layer has a first shear storage modulus of 20 kPa or more and 100 kPa or less at , the second pressure-sensitive adhesive layer has a third thickness of 5 ⁇ m or more and 30 ⁇ m or less, and the second pressure-sensitive adhesive layer has a viscosity of 150 kPa or more at 25 ° C.
  • the first cover film has a fourth thickness of 40 ⁇ m or more and 80 ⁇ m or less
  • the second cover film has a fifth thickness of 40 ⁇ m or more and 80 ⁇ m or less
  • the 5 The ratio of the fourth thickness to the thickness is 1 or more
  • the second pressure-sensitive adhesive layer and the second cover film form a second pressure-sensitive adhesive layer-attached second cover film
  • the first cover film The ratio of the first peel force for peeling from the first pressure-sensitive adhesive layer to the second peel force for peeling the second cover film with the second pressure-sensitive adhesive layer from the optical film is 0.9 or less. and wherein the first peel force is 10 gf/25 mm or less.
  • the present invention [5] includes the optical film with a cover film according to [4] above, wherein the ratio of the second thickness to the third thickness is 1 or more and 100 or less.
  • the present invention [6] includes the optical film with a cover film according to [4] or [5] above, wherein the ratio of the first shear storage modulus to the second shear storage modulus is 0.5 or less. .
  • the present invention [7] includes the optical film with a cover film according to any one of [1] to [6] above, wherein the optical film is a polarizing film.
  • the present invention [8] is the optical film with a cover film according to any one of [1] to [7] above, wherein the polarizing film has a third shear storage elastic modulus of 1.0 ⁇ 10 6 kPa or more. including.
  • the optical film with a cover film of the present invention is suitable for peeling one cover film from a thin optical film with an adhesive layer while suppressing peeling of the other cover film and cracking at the edge of the optical film. .
  • the optical film with a cover film of the present invention is suitable for suppressing peeling of the adhesive layer from the optical film during folding.
  • FIG. 1 represents the first peeling step of peeling the first cover film
  • FIG. 2B represents the first bonding step of bonding the optical film and the first adherend via the first pressure-sensitive adhesive layer
  • 2C represents a second peeling step of peeling the second cover film
  • FIG. 2D represents a second bonding step of bonding the optical film and the second adherend via the second adhesive layer.
  • 2nd Embodiment of the optical film with a cover film of this invention It is a cross-sectional schematic diagram of 2nd Embodiment of the optical film with a cover film of this invention.
  • FIG. 4A shows a peeling step of peeling the first cover film
  • FIG. 4B shows a bonding step of bonding the optical film and the first adherend via the first pressure-sensitive adhesive layer.
  • Optical film X1 as a first embodiment of the optical film with a cover film of the present invention comprises, as shown in FIG. (second adhesive layer), cover film 40 (first cover film), and cover film 50 (second cover film).
  • the optical film X1 has a sheet shape with a predetermined thickness and spreads in a direction orthogonal to the thickness direction T (surface direction).
  • the optical film X1 includes a cover film 50, an adhesive layer 30, an optical film 10, an adhesive layer 20, and a cover film 40 in the thickness direction T in this order.
  • the optical film 10 is a functional optical film in this embodiment.
  • Functional optical films include, for example, film-like polarizing plates (polarizing films) and retardation films.
  • the optical film 10 has a first surface 11 as one surface in the thickness direction and a second surface 12 opposite to the first surface 11 .
  • the adhesive layer 20 adheres to the first surface 11 and has an adhesive surface 21 (first adhesive surface) on the side opposite to the optical film 10 .
  • the adhesive layer 30 adheres to the second surface 12 and has an adhesive surface 31 (second adhesive surface) on the side opposite to the optical film 10 .
  • the optical film 10 and the pressure-sensitive adhesive layers 20 and 30 form the pressure-sensitive adhesive layer-attached optical film Y1.
  • the pressure-sensitive adhesive layer-attached optical film Y1 is an optical film to be incorporated into the laminated structure of the foldable display panel.
  • the optical film X1 includes such an optical film Y1 with an adhesive layer and cover films 40 and 50.
  • the cover film 40 is releasably arranged on the adhesive surface 21 of the optical film Y1 with an adhesive layer.
  • the cover film 50 is releasably arranged on the adhesive surface 31 .
  • the cover films 40, 50 have flexibility.
  • Such an optical film X1 is used as a supply material for the pressure-sensitive adhesive layer-attached optical film Y1 incorporated in the laminated structure of the foldable display panel in the manufacturing process of the same panel.
  • the cover films 40 and 50 are each peeled off from the pressure-sensitive adhesive layer-attached optical film Y1 at a predetermined timing during the manufacturing process of the foldable display panel.
  • the cover film 40 is peeled off before the cover film 50 is removed. That is, in the optical film X1, the cover film 40 is the pre-release film and the cover film 50 is the post-release film.
  • the optical film 10 has a thickness H1 (first thickness) of 100 ⁇ m or less.
  • the thickness H1 is preferably 80 ⁇ m or less, more preferably 60 ⁇ m or less, and even more preferably 40 ⁇ m or less.
  • the thickness H1 is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and even more preferably 10 ⁇ m or more.
  • the adhesive layer 20 has a thickness H2 (second thickness) of 5 ⁇ m or more and 100 ⁇ m or less.
  • the thickness H2 is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and even more preferably 30 ⁇ m or more.
  • the thickness H2 is preferably 90 ⁇ m or less, more preferably 80 ⁇ m or less, and even more preferably 70 ⁇ m or less.
  • the adhesive layer 20 has a shear storage modulus M1 (first shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C.
  • the shear storage elastic modulus M1 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less.
  • the shear storage modulus M1 can be measured with a dynamic viscoelasticity measuring device.
  • the measurement mode is the torsion mode
  • the measurement temperature range is -50 ° C. to 150 ° C.
  • the temperature increase rate is 5 ° C./min
  • the frequency is 1 Hz (also in the measurement of the shear storage elastic modulus M2 described later) similar).
  • Methods for adjusting the shear storage modulus M1 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 20, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
  • the adhesive layer 30 has a thickness H3 (third thickness) of 5 ⁇ m or more and 100 ⁇ m or less.
  • the thickness H3 is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and even more preferably 30 ⁇ m or more.
  • the thickness H3 is preferably 90 ⁇ m or less, more preferably 80 ⁇ m or less, and even more preferably 70 ⁇ m or less.
  • the adhesive layer 30 has a shear storage modulus M2 (second shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C.
  • the shear storage elastic modulus M2 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less.
  • Methods for adjusting the shear storage modulus M2 include, for example, selection of the type of base polymer for the adhesive layer 30, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
  • the cover film 40 has a thickness H4 (fourth thickness) of 40 ⁇ m or more and 80 ⁇ m or less. From the viewpoint of ensuring the flexibility of the cover film 40, the thickness H4 is preferably 75 ⁇ m or less, more preferably 70 ⁇ m or less. From the viewpoint of strength of the cover film 40, the thickness H4 is preferably 45 ⁇ m or more, more preferably 48 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the cover film 50 has a thickness H5 (fifth thickness) of 40 ⁇ m or more and 80 ⁇ m or less.
  • the thickness H5 is preferably 75 ⁇ m or less, more preferably 70 ⁇ m or less, from the viewpoint of ensuring the flexibility of the cover film 50 and from the viewpoint of suppressing cracks at the ends of the optical film 10 when the cover film is peeled off.
  • the thickness H5 is preferably 45 ⁇ m or more, more preferably 48 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the ratio (H4/H5) of the thickness H4 to the thickness H5 is 1 or less in this embodiment. From the viewpoint of suppressing peeling of the cover film 50 when the cover film 40 is peeled off, the ratio (H4/H5) is preferably 0.9 or less, more preferably 0.8 or less. The ratio (H4/H5) is, for example, 0.1 or more.
  • the ratio (F1 /F2) is 0.9 or less. From the viewpoint of suppressing peeling of the cover film 50 when the cover film 40 is peeled off, the ratio (F1/F2) is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.6 or less. The ratio (F1/F2) is, for example, 0.1 or more.
  • the peel force F1 and the peel force F2 are each measured in a peel test under conditions of a measurement temperature of 25° C., a peel angle of 180°, and a tensile speed of 300 mm/min.
  • the peeling force F1 is 10 gf/25 mm or less. From the viewpoint of ensuring a good peeling operation when peeling the cover film 40 from the adhesive layer 20, the peeling force F1 is preferably 7 gf/25 mm or less, more preferably 5 gf/25 mm or less, and even more preferably 3 gf/25 mm or less. Particularly preferably, it is 2.5 gf/25 mm or less. From the viewpoint of suppressing unintended peeling of the cover film 40 from the adhesive layer 20, the peel force F1 is preferably 0.1 gf/25 mm or more, more preferably 0.3 gf/25 mm or more, and still more preferably 0.5 gf/25 mm or more. 25 mm or more.
  • Methods for adjusting the peel force F1 include, for example, selection of the type of base polymer for the adhesive layer 20, adjustment of the molecular weight, and adjustment of the blending amount.
  • Selection of the type of base polymer includes selection of the type (structure) of the main chain in the base polymer, and selection of the type and adjustment of the amount of functional groups (the selection of the type of base polymer described later also includes similar).
  • Methods for adjusting the peeling force F1 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 20 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
  • the thickness H1 of the optical film 10 is 100 ⁇ m or less
  • the thickness H2 of the adhesive layer 20 is 5 ⁇ m or more and 100 ⁇ m or less
  • the thickness H3 of the adhesive layer 30 is the adhesive layer 20 has a shear storage modulus M1 of 20 kPa or more and 100 kPa or less
  • the adhesive layer 30 has a shear storage modulus M2 of 20 kPa or more and 100 kPa or less
  • the cover film 40 has a thickness H4.
  • Such an optical film X1 is obtained by removing the cover film 50 from the optical film Y1 (the thin optical film 10 with the pressure-sensitive adhesive layers 20 and 30) and the edge of the optical film 10, as shown in Examples and Comparative Examples below. It is suitable for peeling off the cover film 40 while suppressing cracks in the film.
  • the ratio of the thickness H2 of the adhesive layer 20 to the thickness H3 of the adhesive layer 30 depends on the ease of folding (bendability) of the optical film X1 and the adherence of the adhesive layer. From the viewpoint of followability (step absorbability) when there is a step on the body surface, it is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.3 or more. From the viewpoint of bendability and step absorbability, the ratio (H2/H3) is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.
  • the ratio (M1/M2) of the shear storage modulus M1 of the adhesive layer 20 to the shear storage modulus M2 of the adhesive layer 30 is preferably 0.5 or more, more preferably It is 1 or more, more preferably 1.3 or more, and particularly preferably 1.5 or more.
  • the ratio (M1/M2) is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less, from the viewpoint of bendability and step absorbability.
  • the peel force F2 of the cover film 50 is preferably 0.11 gf/25 mm or more, more preferably 0.33 gf/25 mm or more, and still more preferably 0.55gf/25mm or more.
  • the peeling force F2 is preferably 10 gf/25 mm or less, more preferably 8 gf/25 mm or less, and even more preferably 6 gf/25 mm or less. Particularly preferably, it is 5 gf/25 mm or less.
  • Methods for adjusting the peel force F2 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 30, adjustment of the molecular weight, and adjustment of the blending amount.
  • Methods for adjusting the peel force F2 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 30 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
  • the polarizing film includes, for example, a polarizing film including a polarizer and a transparent protective film attached to one or both sides of the polarizer.
  • Polarizers include, for example, uniaxially stretched hydrophilic polymer films to which a dichroic substance is adsorbed, and oriented polyene films.
  • Hydrophilic polymer films include, for example, polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films.
  • Dichroic substances include, for example, iodine and dichroic dyes.
  • Examples of oriented polyene films include dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.
  • a thin polarizer with a thickness of 10 ⁇ m or less may be used as the polarizer.
  • Examples of thin polarizers include polarizers described in JP-A-51-069644, JP-A-2000-338329, WO2010/100917, Japanese Patent No. 4691205, and Japanese Patent No. 4751481. .
  • the transparent protective film a film that is excellent in transparency, mechanical strength, thermal stability, water barrier properties, and optical isotropy is preferred.
  • Materials for such transparent protective films include, for example, cellulose resins, cyclic polyolefin resins, acrylic resins, phenylmaleimide resins, and polycarbonate resins.
  • the adhesive layer 20 is a pressure-sensitive adhesive layer formed from the first adhesive composition.
  • the adhesive layer 20 has transparency (visible light transmittance).
  • the first PSA composition contains at least a base polymer.
  • the base polymer is an adhesive component that makes the adhesive layer 20 exhibit adhesiveness.
  • Base polymers include, for example, acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers.
  • the base polymer may be used alone or in combination of two or more. From the viewpoint of ensuring good transparency and adhesiveness in the pressure-sensitive adhesive layer 20, an acrylic polymer is preferably used as the base polymer.
  • the acrylic polymer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester.
  • (Meth)acrylic acid means acrylic acid and/or methacrylic acid.
  • the (meth)acrylic acid alkyl ester a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms is preferably used.
  • the (meth)acrylic acid alkyl ester may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.
  • Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate.
  • Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and tricyclic (Meth)acrylic acid esters having the above aliphatic hydrocarbon ring can be mentioned.
  • Cycloalkyl (meth)acrylates include, for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate.
  • Examples of (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate.
  • (Meth)acrylic esters having a tricyclic or higher aliphatic hydrocarbon ring include, for example, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate , 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.
  • an acrylate alkyl ester having an alkyl group having 3 to 15 carbon atoms is preferably used, and more preferably n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. At least one selected from the group consisting of dodecyl is used.
  • the ratio of the (meth)acrylic acid alkyl ester in the monomer component is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably from the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer 20. is 70% by mass or more. The same ratio is, for example, 99% by mass or less.
  • the monomer component may contain a copolymerizable monomer that can be copolymerized with the (meth)acrylic acid alkyl ester.
  • copolymerizable monomers include monomers having a polar group.
  • Polar group-containing monomers include, for example, nitrogen atom-containing ring-containing monomers, hydroxy group-containing monomers, and carboxy group-containing monomers.
  • the polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing cross-linking points into the acrylic polymer and securing the cohesive strength of the acrylic polymer.
  • Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N -vinylthiazole,
  • the ratio of the monomer having a nitrogen atom-containing ring in the monomer component is preferably 0.1 mass from the viewpoint of ensuring the cohesive force in the adhesive layer 20 and ensuring the adhesive strength of the adhesive layer 20 to the adherend. % or more, more preferably 0.3 mass % or more, and still more preferably 0.55 mass % or more.
  • the same ratio is preferably 30% by mass from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the adhesive layer 20). Below, more preferably 20% by mass or less.
  • hydroxy group-containing monomers examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, ( 4-hydroxybutyl meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.
  • 4-hydroxybutyl (meth)acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.
  • the ratio of the hydroxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the pressure-sensitive adhesive layer 20. It is at least 0.8% by mass, more preferably at least 0.8% by mass. The same ratio is preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the pressure-sensitive adhesive layer 20). .
  • Carboxy group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.
  • the ratio of the carboxyl group-containing monomer in the monomer component is preferable from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer 20, and ensuring adhesion to the adherend in the adhesive layer 20. is 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 0.8% by mass or more.
  • the same ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of acid corrosion of the adherend.
  • the adhesive layer 20 preferably has a small acid content.
  • the acid content of the adhesive layer 20 is preferably small in order to suppress polyene formation of the polyvinyl alcohol polarizer due to the acid component.
  • the content of organic acid monomers (for example, (meth)acrylic acid and carboxyl group-containing monomers) in such an acid-free pressure-sensitive adhesive layer 20 is preferably 100 ppm or less, more preferably 70 ppm or less, and still more preferably 50 ppm or less. be.
  • the organic acid monomer content of the adhesive layer 20 is obtained by quantifying the acid monomer extracted into water by immersing the adhesive layer 20 in pure water and heating at 100° C. for 45 minutes by ion chromatography. is required by
  • the base polymer in the pressure-sensitive adhesive layer 20 does not substantially contain an organic acid monomer as a monomer component.
  • the ratio of the organic acid monomer in the monomer component is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.05% by mass. is 0% by mass.
  • the monomer component may contain other copolymerizable monomers.
  • Other copolymerizable monomers include, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. be done. These other copolymerizable monomers may be used alone, or two or more of them may be used in combination.
  • the base polymer has a crosslinked structure in this embodiment.
  • the base polymer having a functional group capable of reacting with the crosslinker and the crosslinker are blended in the first adhesive composition, and the base polymer and the crosslinker are added to the adhesive layer 20.
  • a base in which a polyfunctional monomer is included in the monomer components forming the base polymer and a branched structure (crosslinked structure) is introduced into the polymer chain by polymerization of the monomer components.
  • a method of forming a polymer (second method) is included. These methods may be used in combination.
  • cross-linking agent used in the first method examples include compounds that react with functional groups (hydroxy groups, carboxy groups, etc.) contained in the base polymer.
  • Such crosslinkers include, for example, isocyanate crosslinkers, peroxide crosslinkers, epoxy crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, carbodiimide crosslinkers, and metal chelate crosslinkers.
  • the cross-linking agents may be used alone, or two or more of them may be used in combination.
  • an isocyanate cross-linking agent As the cross-linking agent, an isocyanate cross-linking agent, a peroxide cross-linking agent, and an epoxy cross-linking agent are preferably used because they are highly reactive with the hydroxy groups and carboxy groups in the base polymer and facilitate the introduction of a cross-linked structure. be done.
  • isocyanate cross-linking agents examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, isocyanates, and polymethylene polyphenyl isocyanates.
  • the isocyanate cross-linking agent also includes derivatives of these isocyanates.
  • isocyanate derivative examples include isocyanurate-modified products and polyol-modified products.
  • Commercially available isocyanate cross-linking agents include, for example, Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), Coronate HX (hexa isocyanurate of methylene diisocyanate, manufactured by Tosoh), and Takenate D110N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals).
  • Peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t- butyl peroxyneodecanoate, t-hexyl peroxypivalate, and t-butyl peroxypivalate.
  • epoxy cross-linking agents include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether. , diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.
  • An isocyanate cross-linking agent (especially a bifunctional isocyanate cross-linking agent) and a peroxide cross-linking agent are preferable from the viewpoint of ensuring appropriate flexibility (thus flexibility) of the pressure-sensitive adhesive layer 20 .
  • An isocyanate cross-linking agent (especially a trifunctional isocyanate cross-linking agent) is preferable from the viewpoint of ensuring the durability of the pressure-sensitive adhesive layer 20 .
  • difunctional isocyanate and peroxide crosslinkers form softer two-dimensional crosslinks, while trifunctional isocyanate crosslinkers form stronger three-dimensional crosslinks.
  • a trifunctional isocyanate cross-linking agent together with a peroxide cross-linking agent and/or a bifunctional isocyanate cross-linking agent.
  • the amount of the cross-linking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and more preferably 100 parts by mass of the base polymer. is 0.07 parts by mass or more.
  • the amount of the cross-linking agent blended with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less. is.
  • the monomer components may be polymerized at once or in multiple stages.
  • a monofunctional monomer for forming the base polymer is polymerized (prepolymerization), thereby containing a partially polymerized product (a mixture of a polymerized product with a low degree of polymerization and an unreacted monomer).
  • a prepolymer composition is prepared.
  • the partial polymer and the polyfunctional monomer are polymerized (main polymerization).
  • polyfunctional monomers examples include polyfunctional (meth)acrylates containing two or more ethylenically unsaturated double bonds in one molecule.
  • a polyfunctional acrylate is preferable from the viewpoint that a crosslinked structure can be introduced by active energy ray polymerization (photopolymerization).
  • Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional or higher polyfunctional (meth)acrylates.
  • bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol di (meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, Examples include di(meth)acryloyl isocyanurate and alkylene oxide-modified bisphenol di(meth)acrylate.
  • trifunctional (meth)acrylates examples include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate.
  • Tetrafunctional or higher polyfunctional (meth)acrylates include, for example, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol pentaacrylate. , and dipentaerythritol hexa(meth)acrylate.
  • the molecular weight of the polyfunctional monomer is preferably 1500 or less, more preferably 1000 or less.
  • the functional group equivalent (g/eq) of the polyfunctional monomer is preferably 50 or more, more preferably 70 or more, and even more preferably 80 or more.
  • the functional group equivalent weight is preferably 500 or less, more preferably 300 or less, still more preferably 200 or less.
  • the acrylic polymer can be formed by polymerizing the above monomer components.
  • Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization.
  • Solution polymerization and UV polymerization are preferred from the viewpoints of transparency, water resistance, and cost of the pressure-sensitive adhesive layer 20 .
  • Ethyl acetate and toluene for example, are used as solvents for solution polymerization.
  • a polymerization initiator for example, a thermal polymerization initiator and a photopolymerization initiator are used as a polymerization initiator.
  • the amount of the polymerization initiator to be used is, for example, 0.05 parts by mass or more and, for example, 1 part by mass or less with respect to 100 parts by mass of the monomer component.
  • Thermal polymerization initiators include, for example, azo polymerization initiators and peroxide polymerization initiators.
  • azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2- imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride mentioned.
  • Peroxide polymerization initiators include, for example, dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxid
  • photopolymerization initiators examples include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, ⁇ -ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, and benzoin photopolymerization initiators.
  • Initiators include benzyl photoinitiators, benzophenone photoinitiators, ketal photoinitiators, thioxanthone photoinitiators, and acylphosphine oxide photoinitiators.
  • a chain transfer agent and/or a polymerization inhibitor may be used for the purpose of molecular weight adjustment.
  • Chain transfer agents include ⁇ -thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and ⁇ -methylstyrene. Dimers are included.
  • the molecular weight of the base polymer can be adjusted by adjusting the type and/or amount of the polymerization initiator.
  • the type and/or amount of the polymerization initiator For example, in radical polymerization, the larger the amount of the polymerization initiator, the higher the radical concentration in the reaction system, the higher the density of reaction initiation points, and the smaller the molecular weight of the base polymer formed.
  • the smaller the amount of the polymerization initiator the lower the density of the reaction initiation points, the easier it is for the polymer chain to extend, and the greater the molecular weight of the base polymer formed.
  • the weight-average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more, from the viewpoint of securing the cohesive force in the pressure-sensitive adhesive layer 20 .
  • the weight-average molecular weight is preferably 5 million or less, more preferably 3 million or less, still more preferably 2 million or less.
  • the weight average molecular weight of the acrylic polymer is calculated by measuring by gel permeation chromatography (GPC) and converting to polystyrene.
  • the glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower.
  • the glass transition temperature is, for example, ⁇ 80° C. or higher.
  • the glass transition temperature (Tg) of the base polymer the glass transition temperature (theoretical value) obtained based on the following Fox formula can be used.
  • the Fox equation is a relational expression between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of a homopolymer of monomers constituting the polymer.
  • Tg represents the glass transition temperature (° C.) of the polymer
  • Wi represents the weight fraction of the monomer i constituting the polymer
  • Tgi represents the glass transition of the homopolymer formed from the monomer i.
  • Literature values can be used for the glass transition temperature of homopolymers.
  • glass transition temperature of a homopolymer of a monomer can also be determined by the method specifically described in JP-A-2007-51271.
  • the first adhesive composition may contain one or more oligomers in addition to the base polymer.
  • an acrylic polymer is used as the base polymer, preferably an acrylic oligomer is used as the oligomer.
  • the acrylic oligomer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.
  • the glass transition temperature of the acrylic oligomer is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 110°C or higher.
  • the glass transition temperature of the acrylic oligomer is, for example, 200° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower.
  • the combined use of a low-Tg acrylic polymer (base polymer) introduced with a cross-linked structure and a high-Tg acrylic oligomer can increase the adhesive strength of the pressure-sensitive adhesive layer 20, especially at high temperatures.
  • the glass transition temperature of the acrylic oligomer is calculated by the above Fox formula.
  • the acrylic oligomer having a glass transition temperature of 60° C. or higher is preferably a (meth)acrylic acid alkyl ester having a chain alkyl group (chain alkyl (meth)acrylate) and a (meth)acrylic acid having an alicyclic alkyl group. It is a polymer of a monomer component containing an acid alkyl ester (alicyclic alkyl (meth)acrylate). Specific examples of these (meth)acrylic acid alkyl esters include, for example, the (meth)acrylic acid alkyl esters described above as the monomer component of the acrylic polymer.
  • methyl methacrylate is preferable because it has a high glass transition temperature and excellent compatibility with the base polymer.
  • Preferred alicyclic alkyl (meth)acrylates are dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate. That is, the acrylic oligomer is a monomer component containing methyl methacrylate and at least one selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate. A coalescence is preferred.
  • the proportion of the alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more.
  • the same ratio is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less.
  • the proportion of chain alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less.
  • the ratio is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more.
  • the weight average molecular weight of the acrylic oligomer is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more.
  • the molecular weight is preferably 30,000 or less, more preferably 10,000 or less, still more preferably 8,000 or less.
  • Such a molecular weight range of the acrylic oligomer is preferable for ensuring the adhesive strength and adhesive holding power of the pressure-sensitive adhesive layer 20 .
  • the acrylic oligomer is obtained by polymerizing the monomer component of the acrylic oligomer.
  • Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization.
  • a polymerization initiator may be used, and a chain transfer agent may be used for the purpose of adjusting the molecular weight.
  • the content of the acrylic oligomer in the pressure-sensitive adhesive layer 20 is preferably 0.5 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the base polymer, in order to sufficiently increase the adhesive strength of the pressure-sensitive adhesive layer 20 . It is 8 parts by mass or more, more preferably 1 part by mass or more.
  • the content of the acrylic oligomer in the adhesive layer 20 is preferably 5 parts by mass or less, more preferably 4 parts by mass with respect to 100 parts by mass of the base polymer. 3 parts by mass or less, more preferably 3 parts by mass or less.
  • the pressure-sensitive adhesive layer 20 when the content of the acrylic oligomer is too large, the haze tends to increase and the transparency tends to decrease due to the decrease in compatibility of the acrylic oligomer.
  • the first adhesive composition may contain a silane coupling agent.
  • the content of the silane coupling agent in the first pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the base polymer.
  • the content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.
  • the first adhesive composition may contain other components as necessary.
  • Other ingredients include, for example, tackifiers, plasticizers, softeners, antidegradants, fillers, colorants, UV absorbers, antioxidants, surfactants, and antistatic agents.
  • the haze of the adhesive layer 20 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less.
  • the haze of the pressure-sensitive adhesive layer 20 can be measured using a haze meter according to JIS K7136 (2000). Examples of the haze meter include "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd. and "HM-150 type” manufactured by Murakami Color Research Laboratory.
  • the total light transmittance of the adhesive layer 20 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher.
  • the total light transmittance of the adhesive layer 20 is, for example, 100% or less.
  • the total light transmittance of the adhesive layer 20 can be measured according to JIS K 7375 (2008).
  • the adhesive layer 30 is a pressure-sensitive adhesive layer formed from the second adhesive composition.
  • the adhesive layer 30 has transparency.
  • the second PSA composition contains at least a base polymer. Examples of the base polymer contained in the second pressure-sensitive adhesive composition include the base polymers described above with respect to the first pressure-sensitive adhesive composition.
  • the base polymer in the first PSA composition and the base polymer in the second PSA composition may be the same or different.
  • the second PSA composition may contain components other than the base polymer. Examples of the components contained in the second pressure-sensitive adhesive composition include the components other than the base polymer described above for the first pressure-sensitive adhesive composition.
  • the composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition may be the same or different. From the viewpoint of adjusting the peeling forces F1 and F2 described above, it is preferable that the composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition are different.
  • the haze of the adhesive layer 30 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less.
  • the haze of the adhesive layer 30 can be measured using a haze meter according to JIS K7136 (2000).
  • the total light transmittance of the adhesive layer 30 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher.
  • the total light transmittance of the adhesive layer 30 is, for example, 100% or less.
  • the total light transmittance of the adhesive layer 30 can be measured according to JIS K 7375 (2008).
  • cover film 40 examples include a flexible plastic film.
  • plastic film examples include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film.
  • the surface of the cover film 40 on the pressure-sensitive adhesive layer 20 side is preferably subjected to release treatment.
  • release treatment examples include silicone release treatment and fluorine release treatment (the same applies to the release treatment described below).
  • the peeling force F1 for peeling the cover film 40 from the pressure-sensitive adhesive layer 20 can be adjusted by adjusting the presence or absence of the peeling treatment, the selection of the type, and the conditions.
  • cover film 50 examples include the plastic films described above with respect to the cover film 40 .
  • the surface of the cover film 50 on the pressure-sensitive adhesive layer 30 side is preferably subjected to release treatment.
  • the peeling force F2 for peeling the cover film 50 from the pressure-sensitive adhesive layer 30 can be adjusted by the presence or absence of the peeling treatment, selection of the type, and adjustment of the conditions.
  • the optical film X1 can be produced, for example, as follows.
  • the optical film 10, the adhesive layer 20 with the cover film 40, and the adhesive layer 30 with the cover film 50 are prepared (preparation step).
  • the adhesive layer 20 with the cover film 40 can be formed by applying the first adhesive composition (varnish) on the cover film 40 to form a coating film, and then drying the coating film.
  • first adhesive composition varnish
  • Examples of the method of applying the first pressure-sensitive adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, Lip coating and die coating can be mentioned (the same applies to other methods of applying other pressure-sensitive adhesive compositions described below).
  • Another release film may be laminated on the adhesive layer 20 on the cover film 40 . This peeling film is peeled off before bonding the optical film 10 and the pressure-sensitive adhesive layer 20 together.
  • the adhesive layer 30 with the cover film 50 can be formed by applying the second adhesive composition (varnish) on the cover film 50 to form a coating film, and then drying the coating film.
  • Another release film may be laminated on the adhesive layer 30 on the cover film 50 . This peeling film is peeled off before bonding the optical film 10 and the adhesive layer 30 together.
  • the first surface 11 of the optical film 10 and the pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 with the cover film 40 are pasted together (first pasting step).
  • the second surface 12 of the optical film 10 and the pressure-sensitive adhesive layer 30 side of the pressure-sensitive adhesive layer 30 with the cover film 50 are pasted together (second pasting step).
  • the first surface 11 and the second surface 12 of the optical film 10, the exposed surface of the pressure-sensitive adhesive layer 20 with the cover film 40, and the exposed surface of the pressure-sensitive adhesive layer 30 with the cover film 50 are preferably attached before the bonding. is plasma treated.
  • the optical film X1 (optical film with cover film) can be manufactured.
  • the optical film X1 may be formed by punching. In punching, for example, a punching machine and a Thomson blade are used.
  • 2A to 2D show an example of how to use the optical film X1.
  • the cover film 40 is peeled off from the adhesive layer 20 of the optical film X1.
  • the cover film 50 side of the optical film X1 is fixed on a work table, force is applied to the edge of the cover film 40 to separate the cover film 40 from the adhesive layer 20 .
  • the adhesive surface 21 of the adhesive layer 20 is exposed.
  • the optical film X1 is formed from the thin optical film 10 with the pressure-sensitive adhesive layers 20 and 30 as described above, while suppressing peeling of the cover film 50 and cracks at the edges of the optical film 10. suitable for stripping.
  • the first member M1 is, for example, one element in the laminated structure of the flexible panel. Examples of such elements include a pixel panel, a touch panel, and a transparent cover film (the same applies to the second member M2 described later).
  • the cover film 50 is peeled off from the adhesive layer 30 as shown in FIG. 2C. Thereby, the adhesive surface 31 of the adhesive layer 30 is exposed.
  • the optical film 10 and the second member M2 are bonded with the adhesive layer 30 interposed therebetween.
  • the optical film X1 is used as described above.
  • Optical film X2 as a second embodiment of the optical film with a cover film of the present invention comprises, as shown in FIG. (second adhesive layer), cover film 40 (first cover film), and cover film 60 (second cover film).
  • the optical film X2 has a sheet shape with a predetermined thickness and spreads in a direction orthogonal to the thickness direction T (surface direction).
  • the optical film X2 includes a cover film 60, an adhesive layer 30, an optical film 10, an adhesive layer 20, and a cover film 40 in the thickness direction T in this order.
  • the optical film X2 differs from the optical film X1 in that it includes an optical film Y2 with an adhesive layer and a cover film 60 with an adhesive layer 30 instead of the optical film Y1 with an adhesive layer and the cover films 40 and 50.
  • the pressure-sensitive adhesive layer-attached optical film Y2 is the same as the pressure-sensitive adhesive layer-attached optical film Y1 except that the pressure-sensitive adhesive layer 30 is not provided.
  • the cover film 60 with the adhesive layer 30 includes the cover film 60 and the adhesive layer 30 on one side of the cover film 60 in the thickness direction T.
  • the cover film 60 is a flexible, transparent surface protection film.
  • the adhesive layer 30 contacts the second surface 12 of the optical film 10 of the optical film Y2 with an adhesive layer.
  • the cover film 60 with the adhesive layer 30 is a surface protective film with an adhesive layer that is detachably arranged on the second surface 12 of the optical film Y2 with the adhesive layer.
  • Other configurations of the optical film X2 are the same as those of the optical film X1.
  • Such an optical film X2 is used as a supply material for the pressure-sensitive adhesive layer-attached optical film Y2 incorporated in the laminated structure of the foldable display panel in the manufacturing process of the same panel.
  • the cover film 40 is peeled off from the pressure-sensitive adhesive layer-attached optical film Y2 at a predetermined timing during the manufacturing process of the foldable display panel.
  • the cover film 60 with the adhesive layer 30 may not be peeled off from the optical film Y2 with the adhesive layer.
  • the optical film 10 has a thickness H1 (first thickness) of 100 ⁇ m or less.
  • the thickness H1 is preferably 80 ⁇ m or less, more preferably 60 ⁇ m or less, and even more preferably 40 ⁇ m or less.
  • the thickness H1 is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and even more preferably 10 ⁇ m or more.
  • the adhesive layer 20 has a thickness H2 (second thickness) of 5 ⁇ m or more and 100 ⁇ m or less.
  • the thickness H2 is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and even more preferably 30 ⁇ m or more.
  • the thickness H2 is preferably 90 ⁇ m or less, more preferably 80 ⁇ m or less, and even more preferably 70 ⁇ m or less.
  • the adhesive layer 20 has a shear storage modulus M1 (first shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C.
  • the shear storage elastic modulus M1 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less.
  • the shear storage modulus M1 can be measured with a dynamic viscoelasticity measuring device.
  • the measurement mode is the torsion mode
  • the measurement temperature range is -50 ° C. to 150 ° C.
  • the temperature increase rate is 5 ° C./min
  • the frequency is 1 Hz (also in the measurement of the shear storage elastic modulus M2 described later) similar).
  • Methods for adjusting the shear storage modulus M1 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 20, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
  • the adhesive layer 30 has a thickness H3 (third thickness) of 5 ⁇ m or more and 30 ⁇ m or less. From the viewpoint of ensuring sufficient adhesive strength in the adhesive layer 30, the thickness H3 is preferably 7 ⁇ m or more, more preferably 10 ⁇ m or more. The thickness H3 is preferably 25 ⁇ m or less, more preferably 20 ⁇ m or less, from the viewpoint of suppressing the peeling force for peeling the cover film 60 with the pressure-sensitive adhesive layer 30 from the optical film 10 .
  • the adhesive layer 30 has a shear storage modulus M2 (second shear storage modulus) of 150 kPa or more at 25°C.
  • the shear storage elastic modulus M2 is preferably 500 kPa or more, more preferably It is 1500 kPa or more, more preferably 2000 kPa or more, and preferably 5000 kPa or less, more preferably 4500 kPa or less, and still more preferably 4000 kPa or less.
  • Methods for adjusting the shear storage modulus M2 include, for example, selection of the type of base polymer for the adhesive layer 30, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
  • the cover film 40 has a thickness H4 (fourth thickness) of 40 ⁇ m or more and 80 ⁇ m or less. From the viewpoint of ensuring the flexibility of the cover film 40, the thickness H4 is preferably 75 ⁇ m or less, more preferably 70 ⁇ m or less. From the viewpoint of strength of the cover film 40, the thickness H4 is preferably 45 ⁇ m or more, more preferably 48 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the cover film 60 has a thickness H5 (fifth thickness) of 40 ⁇ m or more and 80 ⁇ m or less.
  • the thickness H5 is preferably 75 ⁇ m or less, more preferably 70 ⁇ m or less, from the viewpoint of ensuring the flexibility of the cover film 60 and from the viewpoint of suppressing cracks at the edges of the optical film 10 when the cover film is peeled off.
  • the thickness H5 is preferably 45 ⁇ m or more, more preferably 48 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the ratio (H4/H5) of the thickness H4 to the thickness H5 is 1 or more in this embodiment. From the viewpoint of suppressing peeling of the cover film 60 with the adhesive layer 30 when the cover film 40 is peeled off, the ratio (H4/H5) is preferably 1.1 or more, more preferably 1.2 or more. The ratio (H4/H5) is, for example, 5 or less.
  • the peeling force F1 (first peeling force) for peeling the cover film 40 from the adhesive layer 20, and the peeling force F2 (second peeling force) for peeling the cover film 60 with the adhesive layer 30 from the optical film 10 ratio (F1/F2) to is 0.9 or less.
  • the ratio (F1/F2) is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.7. 6 or less.
  • the ratio (F1/F2) is, for example, 0.1 or more.
  • the peel force F1 and the peel force F2 are each measured in a peel test under conditions of a measurement temperature of 25° C., a peel angle of 180°, and a tensile speed of 300 mm/min.
  • the peeling force F1 is 10 gf/25 mm or less. From the viewpoint of ensuring a good peeling operation when peeling the cover film 40 from the adhesive layer 20, the peeling force F1 is preferably 7 gf/25 mm or less, more preferably 5 gf/25 mm or less, and even more preferably 3 gf/25 mm or less. Particularly preferably, it is 2.5 gf/25 mm or less. From the viewpoint of suppressing unintended peeling of the cover film 40 from the adhesive layer 20, the peel force F1 is preferably 0.1 gf/25 mm or more, more preferably 0.3 gf/25 mm or more, and still more preferably 0.5 gf/25 mm or more. 25 mm or more.
  • Methods for adjusting the peel force F1 include, for example, selection of the type of base polymer for the adhesive layer 20, adjustment of the molecular weight, and adjustment of the blending amount.
  • Selection of the type of base polymer includes selection of the type (structure) of the main chain in the base polymer, and selection of the type and adjustment of the amount of functional groups (the selection of the type of base polymer described later also includes similar).
  • Methods for adjusting the peeling force F1 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 20 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
  • the thickness H1 of the optical film 10 is 100 ⁇ m or less
  • the thickness H2 of the adhesive layer 20 is 5 ⁇ m or more and 100 ⁇ m or less
  • the thickness H3 of the adhesive layer 30 is the adhesive layer 20 has a shear storage modulus M1 of 20 kPa or more and 100 kPa or less
  • the adhesive layer 30 has a shear storage modulus M2 of 150 kPa or more
  • the thickness H4 of the cover film 40 is 40 ⁇ m.
  • the thickness H5 of the cover film 60 is 40 ⁇ m or more and 80 ⁇ m or less, the ratio (H4/H5) is 1 or more, and the ratio of the peel force F1 of the cover film 40 to the peel force F2 of the cover film 60 (F1/F2) is 0.9 or less, and the peel force F1 is 10 gf/25 mm or less.
  • Such an optical film X2 is obtained by peeling the cover film 60 with the pressure-sensitive adhesive layer 30 from the optical film Y2 (thin optical film 10 with the pressure-sensitive adhesive layer 20) and the optical film 10 Suitable for peeling off the cover film 40 while suppressing cracks at the ends.
  • the ratio (H2/H3) of the thickness H2 of the pressure-sensitive adhesive layer 20 to the thickness H3 of the pressure-sensitive adhesive layer 30 is preferably 1 or more, more preferably 2, from the viewpoint of bendability and step absorption. Above, more preferably 3 or more, particularly preferably 5 or more. From the viewpoint of bendability and step absorbability, the ratio (H2/H3) is preferably 100 or less, more preferably 50 or less, even more preferably 30 or less, and particularly preferably 20 or less.
  • the ratio (M1/M2) of the shear storage modulus M1 of the adhesive layer 20 to the shear storage modulus M2 of the adhesive layer 30 is preferably 0.5 or less, more preferably It is 0.2 or less, more preferably 0.1 or less, particularly preferably 0.05 or less, particularly preferably 0.02 or less.
  • the ratio (M1/M2) is preferably 0.005 or more, more preferably 0.01 or more, and still more preferably 0.015 or more, from the viewpoint of bendability and step absorbability.
  • the peeling force F2 of the cover film 60 with the adhesive layer 30 is preferably 0.11 gf/25 mm or more, more preferably 0. It is 33 gf/25 mm or more, more preferably 0.55 gf/25 mm or more. From the viewpoint of ensuring a good peeling operation when peeling the cover film 60 from the adhesive layer 30, the peeling force F2 is preferably 20 gf/25 mm or less, more preferably 19 gf/25 mm or less, and even more preferably 18 gf/25 mm or less. be.
  • Methods for adjusting the peel force F2 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 30, adjustment of the molecular weight, and adjustment of the blending amount.
  • Methods for adjusting the peel force F2 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 30 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
  • cover film 60 surface protection film
  • plastic film having both flexibility and transparency.
  • plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film.
  • the optical film X2 can be produced, for example, as follows.
  • the optical film 10, the adhesive layer 20 with the cover film 40, and the cover film 60 with the adhesive layer 30 are prepared (preparation step).
  • the method for forming the pressure-sensitive adhesive layer 20 with the cover film 40 is as described above for the first embodiment.
  • the cover film 60 with the adhesive layer 30 In forming the cover film 60 with the adhesive layer 30, first, the surface of the cover film 60 is plasma-treated. Next, a predetermined adhesive composition (varnish) is applied to the plasma-treated surface of the cover film 60 to form a coating film, and then the coating film is dried. Thereby, the cover film 60 with the adhesive layer 30 is obtained. Another release film may be laminated on the adhesive layer 30 on the cover film 60 . This peeling film is peeled off before bonding the optical film 10 and the adhesive layer 30 together.
  • a predetermined adhesive composition varnish
  • the first surface 11 of the optical film 10 and the pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 with the cover film 40 are pasted together (first pasting step).
  • the first surface 11 of the optical film 10 and the exposed surface of the pressure-sensitive adhesive layer 20 with the cover film 40 are plasma-treated prior to this lamination.
  • the optical film X2 (optical film with cover film) can be produced.
  • the optical film X2 may be formed by punching. In punching, for example, a punching machine and a Thomson blade are used.
  • 4A and 4B show an example of how to use the optical film X2.
  • the cover film 40 is peeled off from the adhesive layer 20 of the optical film X2.
  • the cover film 60 side of the optical film X2 is fixed on a work table, force is applied to the edge of the cover film 40 to separate the cover film 40 from the adhesive layer 20 .
  • the adhesive surface 21 of the adhesive layer 20 is exposed.
  • the optical film X2 suppresses peeling of the cover film 60 with the adhesive layer 30 from the thin optical film 10 with the adhesive layer 20 and cracks at the edges of the optical film 10. Suitable for peeling off the cover film 40 .
  • the first member M1 is, for example, one element in the laminated structure of the flexible panel.
  • Such elements include, for example, pixel panels and touch panels.
  • the optical film X2 is used as described above.
  • ⁇ Preparation of first acrylic base polymer > 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 27 parts by mass of n-butyl acrylate (BA), acrylic acid 7.5 parts by mass of 4-hydroxybutyl (4HBA), 1 part by mass of acrylic acid (AA), and 0.3 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator , and ethyl acetate as solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a first polymer solution containing the first acrylic base polymer. The weight average molecular weight of the first acrylic base polymer in this polymer solution was about 2 million.
  • 2EHA 2-ethylhexyl acrylate
  • BA n-butyl acrylate
  • lauryl acrylate lauryl acrylate
  • LA 8 parts by mass
  • 4-hydroxybutyl acrylate (4HBA) 1 part by mass
  • N-vinyl-2-pyrrolidone (NVP) 0.6 parts by mass
  • 2,2′- as a thermal polymerization initiator
  • a mixture containing 0.3 parts by mass of azobisisobutyronitrile (AIBN) and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction).
  • AIBN azobisisobutyronitrile
  • ethyl acetate 0.6 parts by mass
  • 2,2′- 2,2′- as a thermal polymerization initiator
  • ⁇ Preparation of the third acrylic base polymer 60 parts by mass of 2-ethylhexyl acrylate (2EHA), 36.5 parts by mass of lauryl acrylate (LA), and 4 parts by mass of acrylic acid were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. - 8 parts by weight of hydroxybutyl (4HBA), 2.5 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 0.5 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator. A mixture containing 3 parts by mass and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a third polymer solution containing a third acrylic base polymer. The weight average molecular weight of the third acrylic base polymer in this polymer solution was about 2 million.
  • ⁇ Preparation of the fourth acrylic base polymer 99 parts by mass of butyl acrylate (BA), 1 part by mass of 4-hydroxybutyl acrylate (4HBA), and thermal polymerization start in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube.
  • a mixture containing 0.3 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as an agent and ethyl acetate as a solvent was stirred at 60° C. for 4 hours under a nitrogen atmosphere (polymerization reaction ).
  • the weight average molecular weight of the fourth acrylic base polymer in this polymer solution was about 1.7 million.
  • ⁇ Preparation of the fifth acrylic base polymer > 66 parts by mass of 2-ethylhexyl acrylate (2EHA), 18 parts by mass of 2-hydroxyethyl acrylate (HEA), N - A mixture containing 15 parts by mass of vinyl-2-pyrrolidone (NVP), 0.3 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a fifth polymer solution containing the fifth acrylic base polymer. The weight average molecular weight of the fifth acrylic base polymer in this polymer solution was about 2 million.
  • ⁇ Preparation of the sixth acrylic base polymer 96.2 parts by mass of 2-ethylhexyl acrylate (2EHA) and 3.8 parts by mass of 2-hydroxyethyl acrylate (HEA) were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. parts, 0.3 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and 150 parts by mass of ethyl acetate as a solvent, at 65 ° C. for 6 hours, Stirred under a nitrogen atmosphere (polymerization reaction). This gave a sixth polymer solution containing a sixth acrylic base polymer. The weight average molecular weight of the sixth acrylic base polymer in this polymer solution was 540,000.
  • AIBN 2,2'-azobisisobutyronitrile
  • Example 1 ⁇ Production of first adhesive sheet> A first pressure-sensitive adhesive sheet in Example 1 was produced as follows.
  • first adhesive composition 1.5 parts by mass of an acrylic oligomer per 100 parts by mass of the first acrylic base polymer in the polymer solution, and a first cross-linking agent (product name "Niper BMT-40SV", dibenzoyl peroxide, NOF ), 0.3 parts by mass of the second cross-linking agent (product name "Coronate L", trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Tosoh) 0.02 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) (0.3 parts by mass) was added and mixed to prepare a first adhesive composition.
  • a first cross-linking agent product name "Niper BMT-40SV", dibenzoyl peroxide, NOF
  • second cross-linking agent product name "Coronate L", trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Tosoh
  • a coating film was formed by applying the first pressure-sensitive adhesive composition onto the release-treated surface of release film L1, one surface of which had been subjected to silicone release treatment.
  • the release film L1 is a polyethylene terephthalate (PET) film (product name “DIAFOIL MHE50”, thickness 50 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) with one side subjected to silicone release treatment.
  • PET polyethylene terephthalate
  • the release-treated surface of the release film L2 one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L1.
  • the release film L2 is a PET film (product name “DIAFOIL MRV75”, thickness 75 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
  • the coating film sandwiched between the release film L1 and the release film L2 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to form a transparent first adhesive having a thickness of 50 ⁇ m.
  • a first pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the first pressure-sensitive adhesive sheets with release films L1 and L2 were produced.
  • a second pressure-sensitive adhesive sheet in Example 1 was produced as follows.
  • ⁇ Preparation of second adhesive composition> 1.5 parts by mass of an acrylic oligomer per 100 parts by mass of the solid content of the polymer solution, 0.26 parts by mass of a first cross-linking agent (product name "Nyper BMT-40SV", manufactured by NOF), 0.02 parts by mass of a second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) and 0.3 parts by mass of a silane coupling agent (product name “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) are added and mixed, and the second An adhesive composition was prepared.
  • a first cross-linking agent product name "Nyper BMT-40SV”, manufactured by NOF
  • a second cross-linking agent product name “Coronate L”, manufactured by Tosoh
  • silane coupling agent product name “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.
  • a coating film was formed by applying the second pressure-sensitive adhesive composition onto the release-treated surface of release film L3, one surface of which had been subjected to silicone release treatment.
  • the release film L3 is a polyethylene terephthalate (PET) film (product name “DIAFOIL MHE50”, thickness 50 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) having one side subjected to silicone release treatment.
  • PET polyethylene terephthalate
  • the release-treated surface of the release film L4 one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L3.
  • the release film L4 is a PET film (product name “DIAFOIL MRV75”, thickness 75 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
  • the coating film sandwiched between the release film L3 and the release film L4 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to obtain a transparent second adhesive having a thickness of 50 ⁇ m.
  • a second pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the second adhesive sheets with release films L3 and L4 were produced.
  • the release film L2 was peeled off from the first pressure-sensitive adhesive sheet with a double-sided release film, and the exposed surface thereby exposed was plasma-treated.
  • both surfaces (first surface and second surface) of the polarizing film having a thickness of 31 ⁇ m were also plasma-treated.
  • a plasma irradiation device product name “AP-TO5”, manufactured by Sekisui Kogyo Co., Ltd.
  • the voltage was 160 V
  • the frequency was 10 kHz
  • the treatment speed was 5000 mm / min (also in the plasma treatment described later similar).
  • the exposed surface of the first adhesive sheet and the first surface of the polarizing film were bonded together.
  • the first pressure-sensitive adhesive sheet with the release film L1 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C.
  • the release film L3 was peeled off from the second adhesive sheet with the release films L3 and L4, and the exposed surface was plasma-treated. Then, the exposed surface of the second adhesive sheet and the second surface of the polarizing film were bonded together. In this bonding, the second pressure-sensitive adhesive sheet with the release film L4 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C. As a result, the release film L1 (thickness 50 ⁇ m), the first adhesive sheet (thickness 50 ⁇ m), the polarizing film (thickness 31 ⁇ m), the second adhesive sheet (thickness 50 ⁇ m), the release film L4 (thickness 75 ⁇ m) was obtained.
  • the laminated film was punched into a size of 150 mm x 120 mm (punching).
  • This optical film with a cover film of Example 1 was produced as described above.
  • This optical film with a cover film includes a release film L1 as a first cover film, a first adhesive layer (first adhesive sheet), a polarizing film as an optical film, and a second adhesive layer (second adhesive sheet ) and a release film L4 as a second cover film are provided in order in the thickness direction.
  • Example 2 a polarizing film with a thickness of 51 ⁇ m was used in place of the polarizing film with a thickness of 31 ⁇ m.
  • Example 3 a polarizing film with a thickness of 25 ⁇ m was used in place of the polarizing film with a thickness of 31 ⁇ m.
  • Example 4 the thickness of the first adhesive sheet was changed from 50 ⁇ m to 25 ⁇ m.
  • Example 5 the thickness of the first adhesive sheet was changed from 50 ⁇ m to 25 ⁇ m, and the thickness of the second adhesive sheet was changed from 50 ⁇ m to 75 ⁇ m.
  • Example 6 An optical film with a cover film of Example 6 was produced in the same manner as the optical film with a cover film of Example 1 except for the following.
  • a second polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
  • a third polymer solution was used instead of the second polymer solution, and a second pressure-sensitive adhesive sheet having a thickness of 75 ⁇ m was produced using the second pressure-sensitive adhesive composition.
  • the second polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the second acrylic base polymer in the polymer solution, 1 cross-linking agent (product name “Nyper BMT-40SV”, manufactured by NOF) 0.26 parts by mass, second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • 1 cross-linking agent product name “Nyper BMT-40SV”, manufactured by NOF
  • second cross-linking agent product name “Coronate L”, manufactured by Tosoh
  • silane coupling agent product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • the third polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the third acrylic base polymer in the polymer solution, 1 cross-linking agent (product name "Nyper BMT-40SV", manufactured by NOF) 0.08 parts by mass, second cross-linking agent (product name "Coronate L", manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • 1 cross-linking agent product name "Nyper BMT-40SV", manufactured by NOF
  • second cross-linking agent product name "Coronate L", manufactured by Tosoh
  • silane coupling agent product name 0.3 parts by mass of "KBM403” (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • Example 7 An optical film with a cover film of Example 7 was produced in the same manner as the optical film with a cover film of Example 1 except for the following.
  • a fourth polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
  • the thickness of the second adhesive sheet was changed from 50 ⁇ m to 75 ⁇ m.
  • the fourth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass were added and mixed.
  • a first cross-linking agent product name: Nyper BMT- 40SV", manufactured by NOF
  • a third cross-linking agent product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals
  • a silane coupling agent product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.
  • Comparative Examples 1 to 5 Optical films with cover films of Comparative Examples 1 to 5 were produced in the same manner as the optical film with cover film of Example 1 except for the following.
  • a release film L5 was used instead of the release film L4 (thickness 75 ⁇ m).
  • the release film L5 is a PET film (thickness: 125 ⁇ m) with one side subjected to silicone release treatment.
  • a release film L6 was used instead of the release film L1 (thickness 50 ⁇ m), and a release film L6 was used instead of the release film L4 (thickness 75 ⁇ m).
  • the release film L6 is a PET film (product name “Diafoil MRF38”, thickness 38 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
  • a fifth polymer solution was used in place of the first polymer solution in the preparation of the first pressure-sensitive adhesive composition, and the first pressure-sensitive adhesive composition was used to prepare the first pressure-sensitive adhesive sheet.
  • the fifth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd. ) and 0.3 parts by mass were added and mixed.
  • a first cross-linking agent product name: Nyper BMT- 40SV", manufactured by NOF
  • a third cross-linking agent product name "Takenate D110N", manufactured by Mitsui Chemicals
  • a silane coupling agent product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.
  • the release film L2 was used instead of the release film L1 (thickness 50 ⁇ m)
  • the release film L7 was used instead of the release film L4 (thickness 50 ⁇ m)
  • the thickness of the second adhesive sheet was was changed from 50 ⁇ m to 75 ⁇ m.
  • the release film L7 is a PET film (product name “Diafoil MRF50”, thickness 50 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
  • the release film L2 was used instead of the release film L1 (thickness of 50 ⁇ m)
  • the release film L2 was used instead of the release film L4 (thickness of 50 ⁇ m)
  • the second adhesive sheet was The thickness was changed from 50 ⁇ m to 75 ⁇ m.
  • Example 8 ⁇ Production of first adhesive sheet> A first pressure-sensitive adhesive sheet in Example 8 was produced in the same manner as the above-described first pressure-sensitive adhesive sheet in Example 1.
  • the first pressure-sensitive adhesive sheet in Example 8 is the same as the first pressure-sensitive adhesive sheet in Example 1, specifically the first pressure-sensitive adhesive sheet with release films L1 and L2.
  • This first pressure-sensitive adhesive sheet consists of a transparent first pressure-sensitive adhesive layer with a thickness of 50 ⁇ m.
  • This first pressure-sensitive adhesive layer is composed of 100 parts by mass of the first acrylic base polymer, 1.5 parts by mass of the above acrylic oligomer, and 0.3 parts by mass of the first cross-linking agent (product name "Niper BMT-40SV", manufactured by NOF).
  • a cover film with an adhesive layer in Example 8 was produced as follows.
  • a fourth cross-linking agent product name “Coronate HX”, isocyanurate of hexamethylene diisocyanate, manufactured by Tosoh
  • 0.03 parts by mass of dibutyltin dilaurate as a cross-linking catalyst was added and mixed to prepare a second pressure-sensitive adhesive composition in Example 8.
  • the second pressure-sensitive adhesive composition described above in Example 8 was applied on the corona-treated surface of a surface protective film (product name “T100C-38”, polyester film, thickness 38 ⁇ m, manufactured by Mitsubishi Chemical Corporation) one side of which was corona-treated.
  • a material was applied to form a coating film.
  • the release-treated surface of the release film L8 was attached to the coating film on the surface protection film.
  • the release film L8 is a polyester film (thickness: 25 ⁇ m) with one side subjected to silicone release treatment.
  • the coating film sandwiched between both films was dried by heating at 130° C. for 2 minutes to form a transparent second pressure-sensitive adhesive layer with a thickness of 10 ⁇ m. After that, the release film L8 was peeled off from the second pressure-sensitive adhesive layer.
  • a surface protective film with an adhesive layer cover film with an adhesive layer
  • the release film L2 was peeled off from the first pressure-sensitive adhesive sheet with the double-sided release films L1 and L2, and the exposed surface was plasma-treated.
  • both surfaces (first surface and second surface) of the polarizing film having a thickness of 31 ⁇ m were also plasma-treated.
  • the exposed surface of the first adhesive sheet and the first surface of the polarizing film were bonded together.
  • the first pressure-sensitive adhesive sheet with the release film L1 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C.
  • the pressure-sensitive adhesive layer side of the surface protective film with the pressure-sensitive adhesive layer and the second surface of the polarizing film were adhered together.
  • the pressure-sensitive adhesive layer-attached surface protective film and the polarizing film were pressure-bonded by reciprocating a 2-kg roller once in an environment of 25°C.
  • the release film L1 (thickness 50 ⁇ m), the first adhesive sheet (thickness 50 ⁇ m), the polarizing film (thickness 31 ⁇ m), and the surface protective film (thickness 38 ⁇ m) with the adhesive layer (thickness 10 ⁇ m)
  • the laminated film was punched into a size of 150 mm x 120 mm (punching).
  • This optical film with a cover film of Example 8 was produced as described above.
  • This optical film with a cover film includes a release film L1 as a first cover film, a first pressure-sensitive adhesive layer (first pressure-sensitive adhesive sheet), a polarizing film as an optical film, and a second cover film with a second pressure-sensitive adhesive layer.
  • Example 9 a polarizing film with a thickness of 51 ⁇ m was used in place of the polarizing film with a thickness of 31 ⁇ m.
  • Example 10 a polarizing film with a thickness of 25 ⁇ m was used in place of the polarizing film with a thickness of 31 ⁇ m.
  • Example 11 the thickness of the first adhesive sheet was changed from 50 ⁇ m to 25 ⁇ m.
  • Example 12 An optical film with a cover film of Example 12 was produced in the same manner as the optical film with a cover film of Example 8 except for the following.
  • a second polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
  • the second polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the second acrylic base polymer in the polymer solution, 1 cross-linking agent (product name “Nyper BMT-40SV”, manufactured by NOF) 0.26 parts by mass, second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • 1 cross-linking agent product name “Nyper BMT-40SV”, manufactured by NOF
  • second cross-linking agent product name “Coronate L”, manufactured by Tosoh
  • silane coupling agent product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
  • Example 13 An optical film with a cover film of Example 13 was produced in the same manner as the optical film with a cover film of Example 8 except for the following.
  • a fourth polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
  • the fourth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass were added and mixed.
  • a first cross-linking agent product name: Nyper BMT- 40SV", manufactured by NOF
  • a third cross-linking agent product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals
  • a silane coupling agent product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.
  • Comparative Examples 6 to 9 Optical films with cover films of Comparative Examples 6 to 9 were produced in the same manner as the optical film with cover film of Example 8 except for the following.
  • Comparative Example 6 a surface protection film with a thickness of 125 ⁇ m was used as the second cover film instead of the surface protection film with a thickness of 38 ⁇ m.
  • the surface protective film in Comparative Example 6 is a PET film (product name: "Lumirror S10", manufactured by Toray Industries, Inc.) on one side of which is subjected to release treatment with a silicone-based release agent.
  • a fifth polymer solution was used in place of the first polymer solution in the preparation of the first pressure-sensitive adhesive composition, and the first pressure-sensitive adhesive composition was used to prepare the first pressure-sensitive adhesive sheet.
  • the fifth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd. ) and 0.3 parts by mass were added and mixed.
  • a first cross-linking agent product name: Nyper BMT- 40SV", manufactured by NOF
  • a third cross-linking agent product name "Takenate D110N", manufactured by Mitsui Chemicals
  • a silane coupling agent product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.
  • the thickness of the second pressure-sensitive adhesive layer on the surface protection film with the pressure-sensitive adhesive layer was changed from 10 ⁇ m to 1 ⁇ m.
  • a release film L9 was used instead of the release film L1 (thickness: 50 ⁇ m).
  • the release film L9 is a PET film (product name “Diafoil MRF75”, thickness 75 ⁇ m, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
  • Shear storage modulus The shear storage elastic modulus at 25° C. was measured as follows for each pressure-sensitive adhesive layer in each optical film with a cover film of Examples 1 to 13 and Comparative Examples 1 to 9.
  • a sample for measurement we prepared a sample for measurement. Specifically, after laminating a plurality of adhesive layer pieces to prepare an adhesive sheet with a thickness of about 1.5 mm, the sheet is punched to obtain a cylindrical pellet (diameter 7 .9 mm). Then, the measurement sample was fixed to a parallel plate jig with a diameter of 7.9 mm using a dynamic viscoelasticity measuring device (trade name "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific). Dynamic viscoelasticity measurements were performed. In this measurement, the measurement mode was the torsion mode, the measurement temperature range was -50° C. to 150° C., the temperature increase rate was 5° C./min, and the frequency was 1 Hz.
  • AWS Advanced Rheometric Expansion System
  • the shear storage modulus G' at 25°C was read.
  • Tables 1 to 4 show the shear storage modulus G' of the first pressure-sensitive adhesive layer at 25°C as the storage modulus M1 (kPa) at 25°C, and the shear storage modulus of the second pressure-sensitive adhesive layer at 25°C.
  • the elastic modulus G′ is given as the storage modulus M2 (kPa) at 25° C. and the ratio of M1 to M2 is also given.
  • a test piece for measurement (about 25 mm short side x 150 mm long side) was cut out from the optical film with the cover film.
  • the test piece was fixed to a fixing table of a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation). Specifically, after peeling and removing one cover film (second cover film or first cover film) from the test piece, the test piece is fixed to the table through the adhesive layer exposed by the peeling. pasted on.
  • a gripping tape was attached to the other cover film (first cover film or second cover film) located on the exposed surface side of the test piece. This gripping tape had a strong adhesive surface, and the gripping tape was attached to the cover film of the test piece via the strong adhesive surface.
  • a peel test was conducted in which the cover film of the pressure-sensitive adhesive layer in the test piece was peeled off from the pressure-sensitive adhesive layer, and the peel strength was measured as the peel force.
  • the measurement temperature was 25° C.
  • the cover film was peeled off by pulling the gripping tape
  • the peeling angle was 180°
  • the pulling speed was 300 mm/min
  • the peeling length was 100 mm.
  • Tables 1 and 2 show the measured peel forces F1 and F2 (gf/25 mm).
  • Tables 1 and 2 also show the ratio of the peeling force F1 to the peeling force F2.
  • the peel strengths F1 and F2 are average values of the peel strength at a peel length of 20 to 100 mm (the peel strength is stable after passing through the peel initiation force at the start of peeling).
  • a test piece for measurement (about 25 mm short side x 150 mm long side) was cut out from the optical film with the cover film.
  • the test piece was fixed to a fixing table of a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation).
  • the second cover film side of the test piece for measuring the first peel strength was attached to a fixing table with a strong adhesive double-faced tape.
  • the test piece for measuring the second peel force after peeling and removing the first cover film from the test piece, the test piece is placed on the fixing table through the first adhesive layer exposed by the peeling. pasted.
  • a gripping tape was attached to the cover film (first cover film or second cover film) positioned on the exposed surface side of the test piece.
  • This gripping tape had a strong adhesive surface, and the gripping tape was attached to the cover film of the test piece via the strong adhesive surface.
  • a peel test was carried out by peeling the cover film (the first cover film or the second cover film with the pressure-sensitive adhesive layer), and the peel strength was measured as the peel force.
  • the measurement temperature was 25° C.
  • the cover film was peeled off by pulling the gripping tape
  • the peeling angle was 180°
  • the pulling speed was 300 mm/min
  • the peeling length was 100 mm.
  • Tables 1 and 2 show the measured peel forces F1 and F2 (gf/25 mm).
  • Tables 1 and 2 also show the ratio of the peeling force F1 to the peeling force F2.
  • the peel strengths F1 and F2 are average values of the peel strength at a peel length of 20 to 100 mm (the peel strength is stable after passing through the peel initiation force at the start of peeling).
  • samples for evaluation were cut out from the optical films (polarizing films) with double-sided cover films thus prepared. Specifically, a rectangular sample of 35 mm ⁇ 100 mm was cut out from the optical film with the cover film so that the absorption axis direction of the polarizing film was parallel to the long side direction in the sample cut out. The samples were then autoclaved at 35° C. and 0.35 MPa for 15 minutes. Next, the sample was subjected to a flexing test using a planar object no-load U-shaped stretching tester (manufactured by Yuasa System Co., Ltd.).
  • a bending jig was attached to a range of 20 mm from the edge of the sample to each of both ends of the sample in the long side direction, and the sample was fixed to the tester (region of 60 mm in the center of the long side of the sample is in an unfixed state).
  • the sample was bent with a bending radius of 1.3 mm and a bending angle of 180° (the axial direction of the bending moment acting on the sample and the absorption of the polarizing film).
  • the same sample was held in a form perpendicular to the axial direction), and the same sample in this state was held for 240 hours in a thermo-hygrostat at a temperature of 25° C. and a relative humidity of 95% (bending test).
  • the samples were visually observed to confirm the presence or absence of peeling between the optical film (polarizing film) and each cover film at the bent portion.
  • peeling occurred from the ends in the short side direction of the sample.
  • the length (mm) of the gap in the short side direction of the sample was measured.
  • the case where the length of the gap is less than 1 mm is defined as " A case where the length of the void was 1 mm or more and less than 2 mm was evaluated as “Good”, and a case where the length of the void was 2 mm or more was evaluated as "Poor”. Table 1 shows the evaluation results.
  • the optical film with cover film of the present invention is used, for example, as a supply material for the optical film included in the laminated structure of the foldable display panel in the manufacturing process of the same panel.
  • Optical film 11 First surface 12
  • Second surface 20 Adhesive layer (first adhesive layer) 21, 31 Adhesive surface 30

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Polarising Elements (AREA)
  • Laminated Bodies (AREA)
  • Adhesive Tapes (AREA)

Abstract

An optical film (X1) with a cover film according to the present invention is provided with an optical film (10), adhesive layers (20, 30), and cover films (40, 50). The optical film (10) has a thickness of 100 μm or less, the adhesive layers (20, 30) have a thickness of 5 to 100 μm, the cover film (40) has a thickness H4 of 40 to 80 μm, the cover film (50) has a thickness H5 of 40 to 80 μm, and a ratio (H4/H5) is 1 or less. The adhesive layers (20, 30) have a storage modulus of 20 to 100 kPa. The cover film (40) has a first release force of 10 gf/25 mm or less, and the ratio of the first release force to a second release force of the cover film (50) is 0.9 or less.

Description

カバーフィルム付き光学フィルムOptical film with cover film
　本発明は、カバーフィルム付き光学フィルムに関する。 The present invention relates to an optical film with a cover film.
　ディスプレイパネルは、例えば、画素パネル、タッチパネル、および透明カバーフィルムなどを含む積層構造を有する。ディスプレイパネルの積層構造中には、所定の光学機能を有する光学フィルムが設けられる。光学フィルムとしては、例えば、フィルム状の偏光フィルム、および位相差フィルムが挙げられる。光学フィルムは、例えば、光学フィルムの両面のそれぞれに粘着剤層が設けられた粘着剤層付き光学フィルムとして製造される。また、粘着剤層付き光学フィルムは、例えば、粘着剤層がカバーフィルムで覆われたカバーフィルム付き光学フィルムとして製造される。このようなカバーフィルム付き光学フィルムについては、例えば下記の特許文献１に記載されている。 A display panel has a laminated structure including, for example, a pixel panel, a touch panel, and a transparent cover film. An optical film having a predetermined optical function is provided in the laminated structure of the display panel. Examples of optical films include film-like polarizing films and retardation films. The optical film is produced, for example, as an optical film with an adhesive layer in which an adhesive layer is provided on each of both surfaces of the optical film. Moreover, the optical film with a pressure-sensitive adhesive layer is manufactured as an optical film with a cover film in which the pressure-sensitive adhesive layer is covered with a cover film, for example. Such an optical film with a cover film is described, for example, in Patent Document 1 below.
特開２０２０－１９０７５４号公報JP 2020-190754 A
　スマートフォン用およびタブレット端末用に、繰り返し折り曲げ可能（フォルダブル）なディスプレイパネルの開発が進んでいる。フォルダブルなディスプレイパネルでは、積層構造中の各要素が薄くてフレキシブルであることが求められる。フォルダブルディスプレイパネル用の光学フィルムも、薄くてフレキシブルであることが求められる。 The development of display panels that can be repeatedly folded (foldable) for smartphones and tablet terminals is progressing. Foldable display panels require that each element in the laminate structure be thin and flexible. Optical films for foldable display panels are also required to be thin and flexible.
　しかしながら、上述のカバーフィルム付き光学フィルムでは、従来、粘着剤層付き光学フィルムが薄いほど、一方のカバーフィルムを粘着剤層から剥離するときの剥離開始用の負荷が、光学フィルムの端部において、当該光学フィルムの有意な変形を引き起こしやすい。そのため、一方のカバーフィルムの剥離時に、他方のカバーフィルムの剥離も生じやすい。また、一方のカバーフィルムの剥離時に、光学フィルムの端部にクラックが生じやすい。 However, in the above-described optical film with a cover film, conventionally, the thinner the optical film with an adhesive layer, the more the load for starting peeling when one cover film is peeled from the adhesive layer at the end of the optical film. It tends to cause significant deformation of the optical film. Therefore, when one cover film is peeled off, the other cover film is likely to be peeled off. In addition, cracks are likely to occur at the edges of the optical film when one of the cover films is peeled off.
　また、フォルダブルディスプレイパネル用の粘着剤層付き光学フィルムには、折り曲げ時においても光学フィルムに対して粘着剤層が充分な接着信頼性を示すことが、求められる。しかしながら、デバイスの折り曲げ箇所では、従来、光学フィルムからの粘着剤層の剥がれが生じやすい。デバイスが折り曲げられたとき、当該折り曲げ箇所では、粘着剤層に対してせん断応力などの応力が局所的に作用するからである。当該剥がれの発生は、デバイスの機能不良の原因となり、好ましくない。 In addition, optical films with pressure-sensitive adhesive layers for foldable display panels are required to exhibit sufficient adhesion reliability of the pressure-sensitive adhesive layer to the optical film even when folded. However, conventionally, the pressure-sensitive adhesive layer tends to peel off from the optical film at the bending portion of the device. This is because when the device is folded, stress such as shear stress locally acts on the pressure-sensitive adhesive layer at the folded portion. Occurrence of the peeling causes malfunction of the device and is not preferable.
　本発明は、粘着剤層付きの薄い光学フィルムから、一方のカバーフィルムを、他方のカバーフィルムの剥離と光学フィルム端部のクラックとを抑制しつつ、剥離するのに適するとともに、折り曲げ時における光学フィルムからの粘着剤層の剥がれを抑制するのに適した、カバーフィルム付き光学フィルムを提供する。 INDUSTRIAL APPLICABILITY The present invention is suitable for peeling one cover film from a thin optical film with an adhesive layer while suppressing peeling of the other cover film and cracking at the edge of the optical film, and is suitable for peeling the optical film during bending. To provide an optical film with a cover film suitable for suppressing peeling of an adhesive layer from the film.
　本発明［１］は、第１カバーフィルムと、第１粘着剤層と、光学フィルムと、第２粘着剤層と、第２カバーフィルムとを厚さ方向にこの順で備える、カバーフィルム付き光学フィルムであって、前記光学フィルムが１００μｍ以下の第１厚さを有し、前記第１粘着剤層が５μｍ以上１００μｍ以下の第２厚さを有し、前記第１粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第１せん断貯蔵弾性率を有し、前記第２粘着剤層が５μｍ以上１００μｍ以下の第３厚さを有し、前記第２粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第２せん断貯蔵弾性率を有し、前記第１カバーフィルムが４０μｍ以上８０μｍ以下の第４厚さを有し、前記第２カバーフィルムが４０μｍ以上８０μｍ以下の第５厚さを有し、前記第５厚さに対する前記第４厚さの比率が１以下であり、前記第１カバーフィルムを前記第１粘着剤層から剥離するための第１剥離力の、前記第２カバーフィルムを前記第２粘着剤層から剥離するための第２剥離力に対する比率が、０.９以下であり、前記第１剥離力が１０ｇｆ/２５ｍｍ以下である、カバーフィルム付き光学フィルムを含む。 The present invention [1] provides a cover film-attached optical film comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction. A film, wherein the optical film has a first thickness of 100 µm or less, the first pressure-sensitive adhesive layer has a second thickness of 5 µm or more and 100 µm or less, and the first pressure-sensitive adhesive layer is heated at 25°C. has a first shear storage modulus of 20 kPa or more and 100 kPa or less at , the second pressure-sensitive adhesive layer has a third thickness of 5 μm or more and 100 μm or less, and the second pressure-sensitive adhesive layer has a thickness of 20 kPa or more and 100 kPa at 25 ° C. having the following second shear storage modulus, the first cover film having a fourth thickness of 40 μm or more and 80 μm or less, the second cover film having a fifth thickness of 40 μm or more and 80 μm or less, The ratio of the fourth thickness to the fifth thickness is 1 or less, and the second cover film has a first peel force for peeling the first cover film from the first pressure-sensitive adhesive layer. It includes an optical film with a cover film, wherein the ratio to the second peeling force for peeling from the two pressure-sensitive adhesive layers is 0.9 or less, and the first peeling force is 10 gf/25 mm or less.
　本発明［２］は、前記第３厚さに対する前記第３厚さの比率が０.１以上２以下である、上記［１］に記載のカバーフィルム付き光学フィルムを含む。 The present invention [2] includes the optical film with a cover film according to [1] above, wherein the ratio of the third thickness to the third thickness is 0.1 or more and 2 or less.
　本発明［３］は、前記第２せん断貯蔵弾性率に対する前記第１せん断貯蔵弾性率の比率が０.５以上である、上記［１］または［２］に記載のカバーフィルム付き光学フィルムを含む。 The present invention [3] includes the optical film with a cover film according to [1] or [2] above, wherein the ratio of the first shear storage modulus to the second shear storage modulus is 0.5 or more. .
　本発明［４］は、第１カバーフィルムと、第１粘着剤層と、光学フィルムと、第２粘着剤層と、第２カバーフィルムとを厚さ方向にこの順で備える、カバーフィルム付き光学フィルムであって、前記光学フィルムが１００μｍ以下の第１厚さを有し、前記第１粘着剤層が５μｍ以上１００μｍ以下の第２厚さを有し、前記第１粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第１せん断貯蔵弾性率を有し、前記第２粘着剤層が５μｍ以上３０μｍ以下の第３厚さを有し、前記第２粘着剤層が、２５℃において１５０ｋＰａ以上の第２せん断貯蔵弾性率を有し、前記第１カバーフィルムが４０μｍ以上８０μｍ以下の第４厚さを有し、前記第２カバーフィルムが４０μｍ以上８０μｍ以下の第５厚さを有し、前記第５厚さに対する前記第４厚さの比率が１以上であり、前記第２粘着剤層および前記第２カバーフィルムが、第２粘着剤層付き第２カバーフィルムを形成し、前記第１カバーフィルムを前記第１粘着剤層から剥離するための第１剥離力の、前記第２粘着剤層付き第２カバーフィルムを前記光学フィルムから剥離するための第２剥離力に対する比率が、０.９以下であり、前記第１剥離力が１０ｇｆ/２５ｍｍ以下である、カバーフィルム付き光学フィルムを含む。 The present invention [4] is an optical film with a cover film, comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction. A film, wherein the optical film has a first thickness of 100 µm or less, the first pressure-sensitive adhesive layer has a second thickness of 5 µm or more and 100 µm or less, and the first pressure-sensitive adhesive layer is heated at 25°C. has a first shear storage modulus of 20 kPa or more and 100 kPa or less at , the second pressure-sensitive adhesive layer has a third thickness of 5 μm or more and 30 μm or less, and the second pressure-sensitive adhesive layer has a viscosity of 150 kPa or more at 25 ° C. a second shear storage modulus, the first cover film has a fourth thickness of 40 μm or more and 80 μm or less, the second cover film has a fifth thickness of 40 μm or more and 80 μm or less, and the 5 The ratio of the fourth thickness to the thickness is 1 or more, the second pressure-sensitive adhesive layer and the second cover film form a second pressure-sensitive adhesive layer-attached second cover film, and the first cover film The ratio of the first peel force for peeling from the first pressure-sensitive adhesive layer to the second peel force for peeling the second cover film with the second pressure-sensitive adhesive layer from the optical film is 0.9 or less. and wherein the first peel force is 10 gf/25 mm or less.
　本発明［５］は、前記第３厚さに対する前記第２厚さの比率が１以上１００以下である、上記［４］に記載のカバーフィルム付き光学フィルムを含む。 The present invention [5] includes the optical film with a cover film according to [4] above, wherein the ratio of the second thickness to the third thickness is 1 or more and 100 or less.
　本発明［６］は、前記第２せん断貯蔵弾性率に対する前記第１せん断貯蔵弾性率の比率が０.５以下である、上記［４］または［５］に記載のカバーフィルム付き光学フィルムを含む。 The present invention [6] includes the optical film with a cover film according to [4] or [5] above, wherein the ratio of the first shear storage modulus to the second shear storage modulus is 0.5 or less. .
　本発明［７］は、前記光学フィルムが偏光フィルムである、上記［１］から［６］のいずれか一つに記載のカバーフィルム付き光学フィルムを含む。 The present invention [7] includes the optical film with a cover film according to any one of [1] to [6] above, wherein the optical film is a polarizing film.
　本発明［８］は、前記偏光フィルムが１.０×１０６ｋＰａ以上の第３せん断貯蔵弾性率を有する、上記［１］から［７］のいずれか一つに記載のカバーフィルム付き光学フィルムを含む。 The present invention [8] is the optical film with a cover film according to any one of [1] to [7] above, wherein the polarizing film has a third shear storage elastic modulus of 1.0×10 6 kPa or more. including.
　本発明のカバーフィルム付き光学フィルムは、粘着剤層付きの薄い光学フィルムから、一方のカバーフィルムを、他方のカバーフィルムの剥離と光学フィルム端部のクラックとを抑制しつつ、剥離するのに適する。加えて、本発明のカバーフィルム付き光学フィルムは、折り曲げ時において、光学フィルムからの粘着剤層の剥がれを抑制するのに適する。 The optical film with a cover film of the present invention is suitable for peeling one cover film from a thin optical film with an adhesive layer while suppressing peeling of the other cover film and cracking at the edge of the optical film. . In addition, the optical film with a cover film of the present invention is suitable for suppressing peeling of the adhesive layer from the optical film during folding.
本発明のカバーフィルム付き光学フィルムの第１の実施形態の断面模式図である。BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of 1st Embodiment of the optical film with a cover film of this invention. 図１に示すカバーフィルム付き光学フィルムの使用方法の一例を表す。図２Ａは、第１カバーフィルムを剥離する第１剥離工程を表し、図２Ｂは、第１粘着剤層を介して光学フィルムと第１被着体とを接合する第１接合工程を表し、図２Ｃは、第２カバーフィルムを剥離する第２剥離工程を表し、図２Ｄは、第２粘着剤層を介して光学フィルムと第２被着体とを接合する第２接合工程を表す。An example of the usage method of the optical film with a cover film shown in FIG. 1 is represented. 2A represents the first peeling step of peeling the first cover film, and FIG. 2B represents the first bonding step of bonding the optical film and the first adherend via the first pressure-sensitive adhesive layer. 2C represents a second peeling step of peeling the second cover film, and FIG. 2D represents a second bonding step of bonding the optical film and the second adherend via the second adhesive layer. 本発明のカバーフィルム付き光学フィルムの第２の実施形態の断面模式図である。It is a cross-sectional schematic diagram of 2nd Embodiment of the optical film with a cover film of this invention. 図３に示すカバーフィルム付き光学フィルムの使用方法の一例を表す。図４Ａは、第１カバーフィルムを剥離する剥離工程を表し、図４Ｂは、第１粘着剤層を介して光学フィルムと第１被着体とを接合する接合工程を表す。An example of the usage method of the optical film with a cover film shown in FIG. 3 is represented. FIG. 4A shows a peeling step of peeling the first cover film, and FIG. 4B shows a bonding step of bonding the optical film and the first adherend via the first pressure-sensitive adhesive layer.
　本発明のカバーフィルム付き光学フィルムの第１の実施形態としての光学フィルムＸ１は、図１に示すように、光学フィルム１０と、粘着剤層２０（第１粘着剤層）と、粘着剤層３０（第２粘着剤層）と、カバーフィルム４０（第１カバーフィルム）と、カバーフィルム５０（第２カバーフィルム）とを備える。光学フィルムＸ１は、所定の厚さのシート形状を有し、厚さ方向Ｔと直交する方向（面方向）に広がる。光学フィルムＸ１は、具体的には、カバーフィルム５０と、粘着剤層３０と、光学フィルム１０と、粘着剤層２０と、カバーフィルム４０とを、厚さ方向Ｔに順に備える。 Optical film X1 as a first embodiment of the optical film with a cover film of the present invention comprises, as shown in FIG. (second adhesive layer), cover film 40 (first cover film), and cover film 50 (second cover film). The optical film X1 has a sheet shape with a predetermined thickness and spreads in a direction orthogonal to the thickness direction T (surface direction). Specifically, the optical film X1 includes a cover film 50, an adhesive layer 30, an optical film 10, an adhesive layer 20, and a cover film 40 in the thickness direction T in this order.
　光学フィルム１０は、本実施形態では機能性光学フィルムである。機能性光学フィルムとしては、例えば、フィルム状の偏光板（偏光フィルム）および位相差フィルムが挙げられる。光学フィルム１０は、厚さ方向一方面としての第１面１１と、当該第１面１１とは反対側の第２面１２とを有する。粘着剤層２０は、第１面１１に貼着し、且つ、光学フィルム１０とは反対側に粘着面２１（第１粘着面）を有する。粘着剤層３０は、第２面１２に貼着し、且つ、光学フィルム１０とは反対側に粘着面３１（第２粘着面）を有する。このような光学フィルム１０および粘着剤層２０,３０は、粘着剤層付き光学フィルムＹ１を形成する。粘着剤層付き光学フィルムＹ１は、フォルダブルディスプレイパネルの積層構造中に組み込まれる光学フィルムである。光学フィルムＸ１は、このような粘着剤層付き光学フィルムＹ１と、カバーフィルム４０,５０とを備える。カバーフィルム４０は、粘着剤層付き光学フィルムＹ１における粘着面２１上に剥離可能に配置されている。カバーフィルム５０は、粘着面３１上に剥離可能に配置されている。カバーフィルム４０,５０は、可撓性を有する。 The optical film 10 is a functional optical film in this embodiment. Functional optical films include, for example, film-like polarizing plates (polarizing films) and retardation films. The optical film 10 has a first surface 11 as one surface in the thickness direction and a second surface 12 opposite to the first surface 11 . The adhesive layer 20 adheres to the first surface 11 and has an adhesive surface 21 (first adhesive surface) on the side opposite to the optical film 10 . The adhesive layer 30 adheres to the second surface 12 and has an adhesive surface 31 (second adhesive surface) on the side opposite to the optical film 10 . The optical film 10 and the pressure-sensitive adhesive layers 20 and 30 form the pressure-sensitive adhesive layer-attached optical film Y1. The pressure-sensitive adhesive layer-attached optical film Y1 is an optical film to be incorporated into the laminated structure of the foldable display panel. The optical film X1 includes such an optical film Y1 with an adhesive layer and cover films 40 and 50. As shown in FIG. The cover film 40 is releasably arranged on the adhesive surface 21 of the optical film Y1 with an adhesive layer. The cover film 50 is releasably arranged on the adhesive surface 31 . The cover films 40, 50 have flexibility.
　このような光学フィルムＸ１は、フォルダブルディスプレイパネルの製造過程において、同パネルの積層構造に組み込まれる粘着剤層付き光学フィルムＹ１の供給材として用いられる。カバーフィルム４０,５０は、それぞれ、フォルダブルディスプレイパネルの製造過程において、所定のタイミングで粘着剤層付き光学フィルムＹ１から剥がされる。カバーフィルム４０は、カバーフィルム５０よりも前のタイミングで剥がされる。すなわち、光学フィルムＸ１において、カバーフィルム４０は先剥離フィルムであり、カバーフィルム５０は後剥離フィルムである。 Such an optical film X1 is used as a supply material for the pressure-sensitive adhesive layer-attached optical film Y1 incorporated in the laminated structure of the foldable display panel in the manufacturing process of the same panel. The cover films 40 and 50 are each peeled off from the pressure-sensitive adhesive layer-attached optical film Y1 at a predetermined timing during the manufacturing process of the foldable display panel. The cover film 40 is peeled off before the cover film 50 is removed. That is, in the optical film X1, the cover film 40 is the pre-release film and the cover film 50 is the post-release film.
　光学フィルムＸ１において、光学フィルム１０は、１００μｍ以下の厚さＨ１（第１厚さ）を有する。光学フィルム１０および粘着剤層付き光学フィルムＹ１においてフレキシブルパネルに適した可撓性を確保する観点から、厚さＨ１は、好ましくは８０μｍ以下、より好ましくは６０μｍ以下、更に好ましくは４０μｍ以下である。光学フィルム１０の強度の観点から、厚さＨ１は、好ましくは３μｍ以上、より好ましくは５μｍ以上、更に好ましくは１０μｍ以上である。 In the optical film X1, the optical film 10 has a thickness H1 (first thickness) of 100 μm or less. From the viewpoint of ensuring flexibility suitable for a flexible panel in the optical film 10 and the pressure-sensitive adhesive layer-attached optical film Y1, the thickness H1 is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less. From the viewpoint of strength of the optical film 10, the thickness H1 is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more.
　粘着剤層２０は、５μｍ以上１００μｍ以下の厚さＨ２（第２厚さ）を有する。粘着剤層２０における充分な粘着力を確保する観点から、厚さＨ２は、好ましくは１０μｍ以上、より好ましくは２０μｍ以上、更に好ましくは３０μｍ以上である。粘着剤層２０からカバーフィルム４０を剥離するための剥離力を抑制する観点から、厚さＨ２は、好ましくは９０μｍ以下、より好ましくは８０μｍ以下、更に好ましくは７０μｍ以下である。 The adhesive layer 20 has a thickness H2 (second thickness) of 5 μm or more and 100 μm or less. From the viewpoint of ensuring sufficient adhesive strength in the adhesive layer 20, the thickness H2 is preferably 10 µm or more, more preferably 20 µm or more, and even more preferably 30 µm or more. From the viewpoint of suppressing the peeling force for peeling the cover film 40 from the adhesive layer 20, the thickness H2 is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less.
　粘着剤層２０は、２５℃において２０ｋＰａ以上１００ｋＰａ以下のせん断貯蔵弾性率Ｍ１（第１せん断貯蔵弾性率）を有する。粘着剤層２０の粘着力と、当該粘着剤層２０からカバーフィルム４０を剥離するための剥離力とのバランスの観点から、せん断貯蔵弾性率Ｍ１は、好ましくは３０ｋＰａ以上、より好ましくは４０ｋＰａ以上、更に好ましくは４５ｋＰａ以上であり、また、好ましくは９０ｋＰａ以下、より好ましくは８０ｋＰａ以下、更に好ましくは７５ｋＰａ以下である。せん断貯蔵弾性率Ｍ１は、動的粘弾性測定装置によって測定できる。その測定において、測定モードをねじりモードとし、測定温度範囲を－５０℃～１５０℃とし、昇温速度を５℃/分とし、周波数を１Ｈｚとする（後述のせん断貯蔵弾性率Ｍ２の測定においても同様である）。せん断貯蔵弾性率Ｍ１の調整方法としては、例えば、粘着剤層２０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整、並びに、前記ベースポリマーを架橋する架橋剤の種類の選択および配合量の調整が挙げられる。 The adhesive layer 20 has a shear storage modulus M1 (first shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C. From the viewpoint of the balance between the adhesive force of the adhesive layer 20 and the peeling force for peeling the cover film 40 from the adhesive layer 20, the shear storage elastic modulus M1 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less. The shear storage modulus M1 can be measured with a dynamic viscoelasticity measuring device. In the measurement, the measurement mode is the torsion mode, the measurement temperature range is -50 ° C. to 150 ° C., the temperature increase rate is 5 ° C./min, and the frequency is 1 Hz (also in the measurement of the shear storage elastic modulus M2 described later) similar). Methods for adjusting the shear storage modulus M1 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 20, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
　粘着剤層３０は、５μｍ以上１００μｍ以下の厚さＨ３（第３厚さ）を有する。粘着剤層３０における充分な粘着力を確保する観点から、厚さＨ３は、好ましくは１０μｍ以上、より好ましくは２０μｍ以上、更に好ましくは３０μｍ以上である。粘着剤層３０からカバーフィルム５０を剥離するための剥離力を抑制する観点から、厚さＨ３は、好ましくは９０μｍ以下、より好ましくは８０μｍ以下、更に好ましくは７０μｍ以下である。 The adhesive layer 30 has a thickness H3 (third thickness) of 5 μm or more and 100 μm or less. From the viewpoint of ensuring sufficient adhesive strength in the adhesive layer 30, the thickness H3 is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of suppressing the peeling force for peeling the cover film 50 from the adhesive layer 30, the thickness H3 is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less.
　粘着剤層３０は、２５℃において２０ｋＰａ以上１００ｋＰａ以下のせん断貯蔵弾性率Ｍ２（第２せん断貯蔵弾性率）を有する。粘着剤層３０の粘着力と、当該粘着剤層３０からカバーフィルム５０を剥離するための剥離力とのバランスの観点から、せん断貯蔵弾性率Ｍ２は、好ましくは３０ｋＰａ以上、より好ましくは４０ｋＰａ以上、更に好ましくは４５ｋＰａ以上であり、また、好ましくは９０ｋＰａ以下、より好ましくは８０ｋＰａ以下、更に好ましくは７５ｋＰａ以下である。せん断貯蔵弾性率Ｍ２の調整方法としては、例えば、粘着剤層３０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整、並びに、前記ベースポリマーを架橋する架橋剤の種類の選択および配合量の調整が挙げられる。 The adhesive layer 30 has a shear storage modulus M2 (second shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C. From the viewpoint of the balance between the adhesive force of the adhesive layer 30 and the peeling force for peeling the cover film 50 from the adhesive layer 30, the shear storage elastic modulus M2 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less. Methods for adjusting the shear storage modulus M2 include, for example, selection of the type of base polymer for the adhesive layer 30, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
　カバーフィルム４０は、４０μｍ以上８０μｍ以下の厚さＨ４（第４厚さ）を有する。カバーフィルム４０の可撓性を確保する観点から、厚さＨ４は、好ましくは７５μｍ以下、より好ましくは７０μｍ以下である。カバーフィルム４０の強度の観点から、厚さＨ４は、好ましくは４５μｍ以上、より好ましくは４８μｍ以上、更に好ましくは５０μｍ以上である。 The cover film 40 has a thickness H4 (fourth thickness) of 40 µm or more and 80 µm or less. From the viewpoint of ensuring the flexibility of the cover film 40, the thickness H4 is preferably 75 μm or less, more preferably 70 μm or less. From the viewpoint of strength of the cover film 40, the thickness H4 is preferably 45 μm or more, more preferably 48 μm or more, and even more preferably 50 μm or more.
　カバーフィルム５０は、４０μｍ以上８０μｍ以下の厚さＨ５（第５厚さ）を有する。カバーフィルム５０の可撓性を確保する観点、および、カバーフィルム剥離時における光学フィルム１０端部のクラック抑制の観点から、厚さＨ５は、好ましくは７５μｍ以下、より好ましくは７０μｍ以下である。カバーフィルム４０の強度の観点から、厚さＨ５は、好ましくは４５μｍ以上、より好ましくは４８μｍ以上、更に好ましくは５０μｍ以上である。 The cover film 50 has a thickness H5 (fifth thickness) of 40 μm or more and 80 μm or less. The thickness H5 is preferably 75 μm or less, more preferably 70 μm or less, from the viewpoint of ensuring the flexibility of the cover film 50 and from the viewpoint of suppressing cracks at the ends of the optical film 10 when the cover film is peeled off. From the viewpoint of strength of the cover film 40, the thickness H5 is preferably 45 μm or more, more preferably 48 μm or more, and even more preferably 50 μm or more.
　厚さＨ５に対する上述の厚さＨ４の比率（Ｈ４／Ｈ５）は、本実施形態では、１以下である。カバーフィルム４０の剥離時にカバーフィルム５０の剥離を抑制する観点から、比率（Ｈ４／Ｈ５）は、好ましくは０.９以下、より好ましくは０.８以下である。比率（Ｈ４／Ｈ５）は、例えば０.１以上である。 The ratio (H4/H5) of the thickness H4 to the thickness H5 is 1 or less in this embodiment. From the viewpoint of suppressing peeling of the cover film 50 when the cover film 40 is peeled off, the ratio (H4/H5) is preferably 0.9 or less, more preferably 0.8 or less. The ratio (H4/H5) is, for example, 0.1 or more.
　カバーフィルム４０を粘着剤層２０から剥離するための剥離力Ｆ１（第１剥離力）の、カバーフィルム５０を粘着剤層３０から剥離するための剥離力Ｆ２（第２剥離力）に対する比率（Ｆ１／Ｆ２）は、０.９以下である。カバーフィルム４０の剥離時にカバーフィルム５０の剥離を抑制する観点から、比率（Ｆ１／Ｆ２）は、好ましくは０.８以下、より好ましくは０.７以下、更に好ましくは０.６以下である。比率（Ｆ１／Ｆ２）は、例えば０.１以上である。剥離力Ｆ１および剥離力Ｆ２は、それぞれ、測定温度２５℃、剥離角度１８０°、および引張速度３００ｍｍ／分での条件での剥離試験において測定される。 The ratio (F1 /F2) is 0.9 or less. From the viewpoint of suppressing peeling of the cover film 50 when the cover film 40 is peeled off, the ratio (F1/F2) is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.6 or less. The ratio (F1/F2) is, for example, 0.1 or more. The peel force F1 and the peel force F2 are each measured in a peel test under conditions of a measurement temperature of 25° C., a peel angle of 180°, and a tensile speed of 300 mm/min.
　剥離力Ｆ１は、１０ｇｆ/２５ｍｍ以下である。粘着剤層２０からのカバーフィルム４０の剥離時に良好な剥離作業を確保する観点から、剥離力Ｆ１は、好ましくは７ｇｆ/２５ｍｍ以下、より好ましくは５ｇｆ/２５ｍｍ以下、更に好ましくは３ｇｆ/２５ｍｍ以下、特に好ましくは２.５ｇｆ/２５ｍｍ以下である。粘着剤層２０からのカバーフィルム４０の意図しない剥離を抑制する観点から、剥離力Ｆ１は、好ましくは０.１ｇｆ/２５ｍｍ以上、より好ましくは０.３ｇｆ/２５ｍｍ以上、更に好ましくは０.５ｇｆ/２５ｍｍ以上である。剥離力Ｆ１の調整方法としては、例えば、粘着剤層２０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整が挙げられる。ベースポリマーの種類の選択には、ベースポリマーにおける主鎖の種類（構成）の選択、並びに、官能基の種類の選択および量の調整が含まれる（後記の、ベースポリマーの種類の選択についても、同様である）。剥離力Ｆ１の調整方法としては、粘着剤層２０におけるベースポリマー以外の成分の種類の選択、および、当該成分の配合量の調整も挙げられる。当該成分としては、架橋剤、シランカップリング剤、およびオリゴマーが挙げられる。 The peeling force F1 is 10 gf/25 mm or less. From the viewpoint of ensuring a good peeling operation when peeling the cover film 40 from the adhesive layer 20, the peeling force F1 is preferably 7 gf/25 mm or less, more preferably 5 gf/25 mm or less, and even more preferably 3 gf/25 mm or less. Particularly preferably, it is 2.5 gf/25 mm or less. From the viewpoint of suppressing unintended peeling of the cover film 40 from the adhesive layer 20, the peel force F1 is preferably 0.1 gf/25 mm or more, more preferably 0.3 gf/25 mm or more, and still more preferably 0.5 gf/25 mm or more. 25 mm or more. Methods for adjusting the peel force F1 include, for example, selection of the type of base polymer for the adhesive layer 20, adjustment of the molecular weight, and adjustment of the blending amount. Selection of the type of base polymer includes selection of the type (structure) of the main chain in the base polymer, and selection of the type and adjustment of the amount of functional groups (the selection of the type of base polymer described later also includes similar). Methods for adjusting the peeling force F1 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 20 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
　そして、光学フィルムＸ１は、上述のように、光学フィルム１０の厚さＨ１が１００μｍ以下であり、粘着剤層２０の厚さＨ２が５μｍ以上１００μｍ以下であり、粘着剤層３０の厚さＨ３が５μｍ以上１００μｍ以下であり、粘着剤層２０のせん断貯蔵弾性率Ｍ１が２０ｋＰａ以上１００ｋＰａ以下であり、粘着剤層３０のせん断貯蔵弾性率Ｍ２が２０ｋＰａ以上１００ｋＰａ以下であり、カバーフィルム４０の厚さＨ４が４０μｍ以上８０μｍ以下であり、カバーフィルム５０の厚さＨ５が４０μｍ以上８０μｍ以下であり、比率（Ｈ４／Ｈ５）が１以下であり、カバーフィルム５０の剥離力Ｆ２に対するカバーフィルム４０の剥離力Ｆ１の比率（Ｆ１／Ｆ２）が０.９以下であり、且つ剥離力Ｆ１が１０ｇｆ/２５ｍｍ以下である。このような光学フィルムＸ１は、後記の実施例および比較例をもって示すように、光学フィルムＹ１（粘着剤層２０,３０付きの薄い光学フィルム１０）から、カバーフィルム５０の剥離と光学フィルム１０端部のクラックとを抑制しつつ、カバーフィルム４０を剥離するのに適する。 In the optical film X1, as described above, the thickness H1 of the optical film 10 is 100 μm or less, the thickness H2 of the adhesive layer 20 is 5 μm or more and 100 μm or less, and the thickness H3 of the adhesive layer 30 is the adhesive layer 20 has a shear storage modulus M1 of 20 kPa or more and 100 kPa or less; the adhesive layer 30 has a shear storage modulus M2 of 20 kPa or more and 100 kPa or less; and the cover film 40 has a thickness H4. is 40 μm or more and 80 μm or less, the thickness H5 of the cover film 50 is 40 μm or more and 80 μm or less, the ratio (H4/H5) is 1 or less, and the peel force F1 of the cover film 40 to the peel force F2 of the cover film 50 ratio (F1/F2) is 0.9 or less, and the peel force F1 is 10 gf/25 mm or less. Such an optical film X1 is obtained by removing the cover film 50 from the optical film Y1 (the thin optical film 10 with the pressure-sensitive adhesive layers 20 and 30) and the edge of the optical film 10, as shown in Examples and Comparative Examples below. It is suitable for peeling off the cover film 40 while suppressing cracks in the film.
　光学フィルムＸ１において、粘着剤層３０の厚さＨ３に対する粘着剤層２０の厚さＨ２の比率（Ｈ２／Ｈ３）は、光学フィルムＸ１の折り曲げやすさ（折り曲げ性）と、粘着剤層の被着体表面に段差がある場合の当該段差への追従性（段差吸収性）との観点から、好ましくは０.１以上、より好ましくは０.２以上、更に好ましくは０.３以上である。折り曲げ性および段差吸収性の観点から、比率（Ｈ２／Ｈ３）は、好ましくは２以下、より好ましくは１.５以下、更に好ましくは１.２以下である。 In the optical film X1, the ratio of the thickness H2 of the adhesive layer 20 to the thickness H3 of the adhesive layer 30 (H2/H3) depends on the ease of folding (bendability) of the optical film X1 and the adherence of the adhesive layer. From the viewpoint of followability (step absorbability) when there is a step on the body surface, it is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.3 or more. From the viewpoint of bendability and step absorbability, the ratio (H2/H3) is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.
　粘着剤層３０のせん断貯蔵弾性率Ｍ２に対する粘着剤層２０のせん断貯蔵弾性率Ｍ１の比率（Ｍ１／Ｍ２）は、折り曲げ性および段差吸収性の観点から、好ましくは０.５以上、より好ましくは１以上、更に好ましくは１.３以上、特に好ましくは１.５以上である。折り曲げ性および段差吸収性の観点から、比率（Ｍ１／Ｍ２）は、好ましくは５以下、より好ましくは４以下、更に好ましくは３以下である。 The ratio (M1/M2) of the shear storage modulus M1 of the adhesive layer 20 to the shear storage modulus M2 of the adhesive layer 30 is preferably 0.5 or more, more preferably It is 1 or more, more preferably 1.3 or more, and particularly preferably 1.5 or more. The ratio (M1/M2) is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less, from the viewpoint of bendability and step absorbability.
　カバーフィルム５０の剥離力Ｆ２は、粘着剤層２０からのカバーフィルム４０の意図しない剥離を抑制する観点から、好ましくは０.１１ｇｆ/２５ｍｍ以上、より好ましくは０.３３ｇｆ/２５ｍｍ以上、更に好ましくは０.５５ｇｆ/２５ｍｍ以上である。粘着剤層３０からのカバーフィルム５０の剥離時に良好な剥離作業を確保する観点から、剥離力Ｆ２は、好ましくは１０ｇｆ/２５ｍｍ以下、より好ましくは８ｇｆ/２５ｍｍ以下、更に好ましくは６ｇｆ/２５ｍｍ以下、特に好ましくは５ｇｆ/２５ｍｍ以下である。剥離力Ｆ２の調整方法としては、例えば、粘着剤層３０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整が挙げられる。剥離力Ｆ２の調整方法としては、粘着剤層３０におけるベースポリマー以外の成分の種類の選択、および、当該成分の配合量の調整も挙げられる。当該成分としては、架橋剤、シランカップリング剤、およびオリゴマーが挙げられる。 From the viewpoint of suppressing unintended peeling of the cover film 40 from the adhesive layer 20, the peel force F2 of the cover film 50 is preferably 0.11 gf/25 mm or more, more preferably 0.33 gf/25 mm or more, and still more preferably 0.55gf/25mm or more. From the viewpoint of ensuring a good peeling operation when peeling the cover film 50 from the pressure-sensitive adhesive layer 30, the peeling force F2 is preferably 10 gf/25 mm or less, more preferably 8 gf/25 mm or less, and even more preferably 6 gf/25 mm or less. Particularly preferably, it is 5 gf/25 mm or less. Methods for adjusting the peel force F2 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 30, adjustment of the molecular weight, and adjustment of the blending amount. Methods for adjusting the peel force F2 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 30 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
　光学フィルム１０が偏光フィルムである場合、当該偏光フィルムは、例えば、偏光子と、当該偏光子の片面または両面に貼り合わされた透明保護フィルムとを備える偏光フィルムが挙げられる。偏光子としては、例えば、二色性物質を吸着させた一軸延伸の親水性高分子フィルム、および、ポリエン配向フィルムが挙げられる。親水性高分子フィルムとしては、例えば、ポリビニルアルコールフィルム、部分ホルマール化ポリビニルアルコールフィルム、および、エチレン・酢酸ビニル共重合体部分ケン化フィルムが挙げられる。二色性物質としては、例えば、ヨウ素および二色性染料が挙げられる。ポリエン配向フィルムとしては、例えば、ポリビニルアルコールの脱水処理物、および、ポリ塩化ビニルの脱塩酸処理物が挙げられる。 When the optical film 10 is a polarizing film, the polarizing film includes, for example, a polarizing film including a polarizer and a transparent protective film attached to one or both sides of the polarizer. Polarizers include, for example, uniaxially stretched hydrophilic polymer films to which a dichroic substance is adsorbed, and oriented polyene films. Hydrophilic polymer films include, for example, polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films. Dichroic substances include, for example, iodine and dichroic dyes. Examples of oriented polyene films include dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.
　偏光子としては、厚さ１０μｍ以下の薄型偏光子を用いてもよい。薄型偏光子としては、例えば、特開昭５１－０６９６４４号公報、特開２０００－３３８３２９号公報、ＷＯ２０１０／１００９１７号、特許第４６９１２０５号、および特許第４７５１４８１号に記載されている偏光子が挙げられる。 A thin polarizer with a thickness of 10 μm or less may be used as the polarizer. Examples of thin polarizers include polarizers described in JP-A-51-069644, JP-A-2000-338329, WO2010/100917, Japanese Patent No. 4691205, and Japanese Patent No. 4751481. .
　透明保護フィルムとしては、透明性、機械強度、熱安定性、水分遮断性、および光学等方性に優れるフィルムが好ましい。そのような透明保護フィルムの材料としては、例えば、セルロース樹脂、環状ポリオレフィン樹脂、アクリル樹脂、フェニルマレイミド樹脂、およびポリカーボネート樹脂が挙げられる。 As the transparent protective film, a film that is excellent in transparency, mechanical strength, thermal stability, water barrier properties, and optical isotropy is preferred. Materials for such transparent protective films include, for example, cellulose resins, cyclic polyolefin resins, acrylic resins, phenylmaleimide resins, and polycarbonate resins.
　粘着剤層２０は、第１粘着剤組成物から形成された感圧粘着剤層である。粘着剤層２０は、透明性（可視光透過性）を有する。第１粘着剤組成物は、少なくともベースポリマーを含有する。 The adhesive layer 20 is a pressure-sensitive adhesive layer formed from the first adhesive composition. The adhesive layer 20 has transparency (visible light transmittance). The first PSA composition contains at least a base polymer.
　ベースポリマーは、粘着剤層２０において粘着性を発現させる粘着成分である。ベースポリマーとしては、例えば、アクリルポリマー、シリコーンポリマー、ポリエステルポリマー、ポリウレタンポリマー、ポリアミドポリマー、ポリビニルエーテルポリマー、酢酸ビニル／塩化ビニルコポリマー、変性ポリオレフィンポリマー、エポキシポリマー、フッ素ポリマー、およびゴムポリマーが挙げられる。ベースポリマーは、単独で用いられてもよいし、二種類以上が併用されてもよい。粘着剤層２０における良好な透明性および粘着性を確保する観点から、ベースポリマーとしては、好ましくはアクリルポリマーが用いられる。 The base polymer is an adhesive component that makes the adhesive layer 20 exhibit adhesiveness. Base polymers include, for example, acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. The base polymer may be used alone or in combination of two or more. From the viewpoint of ensuring good transparency and adhesiveness in the pressure-sensitive adhesive layer 20, an acrylic polymer is preferably used as the base polymer.
　アクリルポリマーは、（メタ）アクリル酸アルキルエステルを５０質量％以上の割合で含むモノマー成分の共重合体である。「（メタ）アクリル酸」は、アクリル酸および／またはメタクリル酸を意味する。 The acrylic polymer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester. "(Meth)acrylic acid" means acrylic acid and/or methacrylic acid.
　（メタ）アクリル酸アルキルエステルとしては、アルキル基の炭素数が１～２０である（メタ）アクリル酸アルキルエステルが、好適に用いられる。（メタ）アクリル酸アルキルエステルは、直鎖状または分岐状のアルキル基を有してもよく、脂環式アルキル基など環状のアルキル基を有してもよい。 As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms is preferably used. The (meth)acrylic acid alkyl ester may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.
　直鎖状または分岐状のアルキル基を有する（メタ）アクリル酸アルキルエステルとしては、例えば、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ブチル、（メタ）アクリル酸イソブチル、（メタ）アクリル酸ｓ－ブチル、（メタ）アクリル酸ｔ－ブチル、（メタ）アクリル酸ペンチル、（メタ）アクリル酸イソペンチル、（メタ）アクリル酸ネオペンチル、（メタ）アクリル酸ヘキシル、（メタ）アクリル酸ヘプチル、（メタ）アクリル酸２－エチルヘキシル、（メタ）アクリル酸オクチル、（メタ）アクリル酸イソオクチル、（メタ）アクリル酸ノニル、（メタ）アクリル酸イソノニル、（メタ）アクリル酸デシル、（メタ）アクリル酸イソデシル、（メタ）アクリル酸ウンデシル、（メタ）アクリル酸ドデシル（即ちラウリルアクリレート）、（メタ）アクリル酸イソトリデシル、（メタ）アクリル酸テトラデシル、（メタ）アクリル酸イソテトラデシル、（メタ）アクリル酸ペンタデシル、（メタ）アクリル酸セチル、（メタ）アクリル酸ヘプタデシル、（メタ）アクリル酸オクタデシル、（メタ）アクリル酸イソオクタデシル、および（メタ）アクリル酸ノナデシルが挙げられる。 Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylate Heptyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) ) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (that is, lauryl acrylate), isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, (meth) Pentadecyl acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.
　脂環式アルキル基を有する（メタ）アクリル酸アルキルエステルとしては、例えば、（メタ）アクリル酸シクロアルキルエステル、二環式の脂肪族炭化水素環を有する（メタ）アクリル酸エステル、および、三環以上の脂肪族炭化水素環を有する（メタ）アクリル酸エステルが挙げられる。（メタ）アクリル酸シクロアルキルエステルとしては、例えば、（メタ）アクリル酸シクロペンチル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸シクロヘプチル、および（メタ）アクリル酸シクロオクチルが挙げられる。二環式の脂肪族炭化水素環を有する（メタ）アクリル酸エステルとしては、例えば（メタ）アクリル酸イソボルニルが挙げられる。三環以上の脂肪族炭化水素環を有する（メタ）アクリル酸エステルとしては、例えば、ジシクロペンタニル（メタ）アクリレート、ジシクロペンタニルオキシエチル（メタ）アクリレート、トリシクロペンタニル（メタ）アクリレート、１－アダマンチル（メタ）アクリレート、２－メチル－２－アダマンチル（メタ）アクリレート、および、２－エチル－２－アダマンチル（メタ）アクリレートが挙げられる。 Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and tricyclic (Meth)acrylic acid esters having the above aliphatic hydrocarbon ring can be mentioned. Cycloalkyl (meth)acrylates include, for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. (Meth)acrylic esters having a tricyclic or higher aliphatic hydrocarbon ring include, for example, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate , 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.
　（メタ）アクリル酸アルキルエステルとしては、好ましくは、炭素数３～１５のアルキル基を有するアクリル酸アルキルエステルが用いられ、より好ましくは、アクリル酸ｎ－ブチル、アクリル酸２－エチルヘキシル、およびアクリル酸ドデシルからなる群より選択される少なくとも一つが用いられる。 As the (meth)acrylic acid alkyl ester, an acrylate alkyl ester having an alkyl group having 3 to 15 carbon atoms is preferably used, and more preferably n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. At least one selected from the group consisting of dodecyl is used.
　モノマー成分における（メタ）アクリル酸アルキルエステルの割合は、粘着剤層２０において粘着性等の基本特性を適切に発現させる観点から、好ましくは５０質量％以上、より好ましくは６０質量％以上、更に好ましくは７０質量％以上である。同割合は、例えば９９質量％以下である。 The ratio of the (meth)acrylic acid alkyl ester in the monomer component is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably from the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer 20. is 70% by mass or more. The same ratio is, for example, 99% by mass or less.
　モノマー成分は、（メタ）アクリル酸アルキルエステルと共重合可能な共重合性モノマーを含んでもよい。共重合性モノマーとしては、例えば、極性基を有するモノマーが挙げられる。極性基含有モノマーとしては、例えば、窒素原子含有環を有するモノマー、ヒドロキシ基含有モノマー、およびカルボキシ基含有モノマーが挙げられる。極性基含有モノマーは、アクリルポリマーへの架橋点の導入、アクリルポリマーの凝集力の確保など、アクリルポリマーの改質に役立つ。 The monomer component may contain a copolymerizable monomer that can be copolymerized with the (meth)acrylic acid alkyl ester. Examples of copolymerizable monomers include monomers having a polar group. Polar group-containing monomers include, for example, nitrogen atom-containing ring-containing monomers, hydroxy group-containing monomers, and carboxy group-containing monomers. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing cross-linking points into the acrylic polymer and securing the cohesive strength of the acrylic polymer.
　窒素原子含有環を有するモノマーとしては、例えば、Ｎ－ビニル－２－ピロリドン、Ｎ－メチルビニルピロリドン、Ｎ－ビニルピリジン、Ｎ－ビニルピペリドン、Ｎ－ビニルピリミジン、Ｎ－ビニルピペラジン、Ｎ－ビニルピラジン、Ｎ－ビニルピロール、Ｎ－ビニルイミダゾール、Ｎ－ビニルオキサゾール、Ｎ－(メタ)アクリロイル－２－ピロリドン、Ｎ－(メタ)アクリロイルピペリジン、Ｎ－(メタ)アクリロイルピロリジン、Ｎ－ビニルモルホリン、Ｎ－ビニル－３－モルホリノン、Ｎ－ビニル－２－カプロラクタム、Ｎ－ビニル－１,３－オキサジン－２－オン、Ｎ－ビニル－３,５－モルホリンジオン、Ｎ－ビニルピラゾール、Ｎ－ビニルイソオキサゾール、Ｎ－ビニルチアゾール、およびＮ－ビニルイソチアゾールが挙げられる。窒素原子含有環を有するモノマーとしては、好ましくはＮ－ビニル－２－ピロリドンが用いられる。 Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N -vinylthiazole, and N-vinylisothiazole. N-vinyl-2-pyrrolidone is preferably used as the monomer having a nitrogen atom-containing ring.
　モノマー成分における、窒素原子含有環を有するモノマーの割合は、粘着剤層２０における凝集力の確保、および、粘着剤層２０における対被着体密着力の確保の観点から、好ましくは０.１質量％以上、より好ましくは０.３質量％以上、更に好ましくは０.５５質量％以上である。同割合は、アクリルポリマーのガラス転移温度の調整、および、アクリルポリマーの極性（粘着剤層２０における各種添加剤成分とアクリルポリマーとの相溶性に関わる）の調整の観点から、好ましくは３０質量％以下、より好ましくは２０質量％以下である。 The ratio of the monomer having a nitrogen atom-containing ring in the monomer component is preferably 0.1 mass from the viewpoint of ensuring the cohesive force in the adhesive layer 20 and ensuring the adhesive strength of the adhesive layer 20 to the adherend. % or more, more preferably 0.3 mass % or more, and still more preferably 0.55 mass % or more. The same ratio is preferably 30% by mass from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the adhesive layer 20). Below, more preferably 20% by mass or less.
　ヒドロキシ基含有モノマーとしては、例えば、(メタ)アクリル酸２－ヒドロキシエチル、(メタ)アクリル酸２－ヒドロキシプロピル、(メタ)アクリル酸２－ヒドロキシブチル、(メタ)アクリル酸３－ヒドロキシプロピル、(メタ)アクリル酸４－ヒドロキシブチル、(メタ)アクリル酸６－ヒドロキシヘキシル、(メタ)アクリル酸８－ヒドロキシオクチル、(メタ)アクリル酸１０－ヒドロキシデシル、(メタ)アクリル酸１２－ヒドロキシラウリル、および(４－ヒドロキシメチルシクロへキシル)メチル(メタ)アクリレートが挙げられる。ヒドロキシ基含有モノマーとしては、好ましくは(メタ)アクリル酸４－ヒドロキシブチルが用いられ、より好ましくはアクリル酸４－ヒドロキシブチルが用いられる。 Examples of hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, ( 4-hydroxybutyl meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxy group-containing monomer, 4-hydroxybutyl (meth)acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.
　モノマー成分におけるヒドロキシ基含有モノマーの割合は、アクリルポリマーへの架橋構造の導入、および、粘着剤層２０における凝集力の確保の観点から、好ましくは０.１質量％以上、より好ましくは０.５質量％以上、更に好ましくは０.８質量％以上である。
同割合は、アクリルポリマーの極性（粘着剤層２０における各種添加剤成分とアクリルポリマーとの相溶性に関わる）の調整の観点から、好ましくは２０質量％以下、より好ましくは１０質量％以下である。 The ratio of the hydroxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the pressure-sensitive adhesive layer 20. It is at least 0.8% by mass, more preferably at least 0.8% by mass.
The same ratio is preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the pressure-sensitive adhesive layer 20). .
　カルボキシ基含有モノマーとしては、例えば、アクリル酸、メタクリル酸、カルボキシエチルアクリレート、カルボキシペンチルアクリレート、イタコン酸、マレイン酸、フマル酸、クロトン酸、およびイソクロトン酸が挙げられる。 Carboxy group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.
　モノマー成分におけるカルボキシ基含有モノマーの割合は、アクリルポリマーへの架橋構造の導入、粘着剤層２０における凝集力の確保、および、粘着剤層２０における対被着体密着力の確保の観点から、好ましくは０.１質量％以上、より好ましくは０.５質量％以上、更に好ましくは０.８質量％以上である。同割合は、アクリルポリマーのガラス転移温度の調整、および、酸による被着体の腐食リスクの回避の観点から、好ましくは３０質量％以下、より好ましくは２０質量％以下である。 The ratio of the carboxyl group-containing monomer in the monomer component is preferable from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer 20, and ensuring adhesion to the adherend in the adhesive layer 20. is 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 0.8% by mass or more. The same ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of acid corrosion of the adherend.
　フォルダブルディスプレイパネルにおける電極など金属要素が酸成分によって腐食することを防止するには、粘着剤層２０は、酸の含有量が小さいことが好ましい。また、粘着剤層２０が偏光フィルムの接着に用いられる場合、酸成分によるポリビニルアルコール偏光子のポリエン化を抑制するために、粘着剤層２０は、酸の含有量が小さいことが好ましい。このような酸フリーの粘着剤層２０における有機酸モノマー（例えば、（メタ）アクリル酸およびカルボキシル基含有モノマー）の含有量は、好ましくは１００ｐｐｍ以下、より好ましくは７０ｐｐｍ以下、更に好ましくは５０ｐｐｍ以下である。粘着剤層２０の有機酸モノマー含有量は、粘着剤層２０を純水中に浸漬して１００℃で４５分加温することによって水中に抽出された酸モノマーを、イオンクロマトグラフで定量することにより、求められる。 In order to prevent metal elements such as electrodes in a foldable display panel from being corroded by acid components, the adhesive layer 20 preferably has a small acid content. Moreover, when the adhesive layer 20 is used for bonding a polarizing film, the acid content of the adhesive layer 20 is preferably small in order to suppress polyene formation of the polyvinyl alcohol polarizer due to the acid component. The content of organic acid monomers (for example, (meth)acrylic acid and carboxyl group-containing monomers) in such an acid-free pressure-sensitive adhesive layer 20 is preferably 100 ppm or less, more preferably 70 ppm or less, and still more preferably 50 ppm or less. be. The organic acid monomer content of the adhesive layer 20 is obtained by quantifying the acid monomer extracted into water by immersing the adhesive layer 20 in pure water and heating at 100° C. for 45 minutes by ion chromatography. is required by
　酸フリーの観点からは、粘着剤層２０中のベースポリマーがモノマー成分として有機酸モノマーを実質的に含有しないことが好ましい。酸フリーの観点からは、モノマー成分における有機酸モノマーの割合は、好ましくは０.５質量％以下、より好ましくは０.１質量％以下、更に好ましくは０.０５質量％であり、理想的には０質量％である。 From the standpoint of acid-free, it is preferable that the base polymer in the pressure-sensitive adhesive layer 20 does not substantially contain an organic acid monomer as a monomer component. From the viewpoint of acid-free, the ratio of the organic acid monomer in the monomer component is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.05% by mass. is 0% by mass.
　モノマー成分は、他の共重合性モノマーを含んでいてもよい。他の共重合性モノマーとしては、例えば、酸無水物モノマー、スルホン酸基含有モノマー、リン酸基含有モノマー、エポキシ基含有モノマー、シアノ基含有モノマー、アルコキシ基含有モノマー、および芳香族ビニル化合物が挙げられる。これら他の共重合性モノマーは、単独で用いられてもよいし、二種類以上が併用されてもよい。 The monomer component may contain other copolymerizable monomers. Other copolymerizable monomers include, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. be done. These other copolymerizable monomers may be used alone, or two or more of them may be used in combination.
　ベースポリマーは、本実施形態では、架橋構造を有する。ベースポリマーへの架橋構造の導入方法としては、架橋剤と反応可能な官能基を有するベースポリマーと架橋剤とを第１粘着剤組成物に配合し、ベースポリマーと架橋剤とを粘着剤層２０中で反応させる方法（第１の方法）、および、ベースポリマーを形成するモノマー成分に多官能モノマーを含め、当該モノマー成分の重合により、ポリマー鎖に分枝構造（架橋構造）が導入されたベースポリマーを形成する方法（第２の方法）が、挙げられる。これら方法は、併用されてもよい。 The base polymer has a crosslinked structure in this embodiment. As a method for introducing a crosslinked structure into the base polymer, the base polymer having a functional group capable of reacting with the crosslinker and the crosslinker are blended in the first adhesive composition, and the base polymer and the crosslinker are added to the adhesive layer 20. A base in which a polyfunctional monomer is included in the monomer components forming the base polymer and a branched structure (crosslinked structure) is introduced into the polymer chain by polymerization of the monomer components. A method of forming a polymer (second method) is included. These methods may be used in combination.
　上記第１の方法で用いられる架橋剤としては、例えば、ベースポリマーに含まれる官能基（ヒドロキシ基およびカルボキシ基など）と反応する化合物が挙げられる。そのような架橋剤としては、例えば、イソシアネート架橋剤、過酸化物架橋剤、エポキシ架橋剤、オキサゾリン架橋剤、アジリジン架橋剤、カルボジイミド架橋剤、および金属キレート架橋剤が挙げられる。架橋剤は、単独で用いられてもよいし、二種類以上が併用されてもよい。架橋剤としては、ベースポリマーにおけるヒドロキシ基およびカルボキシ基との反応性が高くて架橋構造の導入が容易であることから、好ましくは、イソシアネート架橋剤、過酸化物架橋剤、およびエポキシ架橋剤が用いられる。 Examples of the cross-linking agent used in the first method include compounds that react with functional groups (hydroxy groups, carboxy groups, etc.) contained in the base polymer. Such crosslinkers include, for example, isocyanate crosslinkers, peroxide crosslinkers, epoxy crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, carbodiimide crosslinkers, and metal chelate crosslinkers. The cross-linking agents may be used alone, or two or more of them may be used in combination. As the cross-linking agent, an isocyanate cross-linking agent, a peroxide cross-linking agent, and an epoxy cross-linking agent are preferably used because they are highly reactive with the hydroxy groups and carboxy groups in the base polymer and facilitate the introduction of a cross-linked structure. be done.
　イソシアネート架橋剤としては、例えば、トリレンジイソシアネート、ヘキサメチレンジイソシアネート、イソホロンジイソシアネート、キシリレンジイソシアネート、水添キシリレンジイソシアネート、ジフェニルメタンジイソシアネート、水添ジフェニルメタンジイソシアネート、テトラメチルキシリレンジイソシアネート、ナフタリンジイソシアネート、トリフェニルメタントリイソシアネート、およびポリメチレンポリフェニルイソシアネートが挙げられる。また、イソシアネート架橋剤としては、これらイソシアネートの誘導体も挙げられる。当該イソシアネート誘導体としては、例えば、イソシアヌレート変性体およびポリオール変性体が挙げられる。イソシアネート架橋剤の市販品としては、例えば、コロネートＬ（トリレンジイソシアネートのトリメチロールプロパンアダクト体，東ソー製）、コロネートＨＬ（へキサメチレンジイソシアネートのトリメチロールプロパンアダクト体，東ソー製）、コロネートＨＸ（ヘキサメチレンジイソシアネートのイソシアヌレート体，東ソー製）、およびタケネートＤ１１０Ｎ（キシリレンジイソシアネートのトリメチロールプロパンアダクト体，三井化学製）が挙げられる。 Examples of isocyanate cross-linking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, isocyanates, and polymethylene polyphenyl isocyanates. The isocyanate cross-linking agent also includes derivatives of these isocyanates. Examples of the isocyanate derivative include isocyanurate-modified products and polyol-modified products. Commercially available isocyanate cross-linking agents include, for example, Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), Coronate HX (hexa isocyanurate of methylene diisocyanate, manufactured by Tosoh), and Takenate D110N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals).
　過酸化物架橋剤としては、ジベンゾイルパーオキシド、ジ（２－エチルヘキシル）パーオキシジカーボネート、ジ（４－ｔ－ブチルシクロヘキシル）パーオキシジカーボネート、ジ－ｓｅｃ－ブチルパーオキシジカーボネート、ｔ－ブチルパーオキシネオデカノエート、ｔ－ヘキシルパーオキシピバレート、およびｔ－ブチルパーオキシピバレートが挙げられる。 Peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t- butyl peroxyneodecanoate, t-hexyl peroxypivalate, and t-butyl peroxypivalate.
　エポキシ架橋剤としては、ビスフェノールＡ、エピクロルヒドリン型のエポキシ樹脂、エチレングリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、グリセリンジグリシジルエーテル、グリセリントリグリシジルエーテル、１,６-ヘキサンジオールグリシジルエーテル、トリメチロールプロパントリグリシジルエーテル、ジグリシジルアニリン、ジアミングリシジルアミン、Ｎ,Ｎ,Ｎ',Ｎ'-テトラグリシジル-ｍ-キシリレンジアミン、および１,３-ビス(Ｎ,Ｎ-ジグリシジルアミノメチル)シクロヘキサンが挙げられる。 Examples of epoxy cross-linking agents include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether. , diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.
　イソシアネート架橋剤(特に、二官能のイソシアネート架橋剤)および過酸化物架橋剤は、粘着剤層２０の適度な柔軟性（従って屈曲性）の確保の観点から好ましい。イソシアネート架橋剤（特に、三官能のイソシアネート架橋剤)は、粘着剤層２０の耐久性確保の観点から好ましい。ベースポリマーにおいて、二官能イソシアネート架橋剤および過酸化物架橋剤は、より柔軟な二次元架橋を形成するのに対し、三官能イソシアネート架橋剤は、より強固な三次元架橋を形成する。粘着剤層２０の耐久性と柔軟性との両立の観点からは、三官能イソシアネート架橋剤と、過酸化物架橋剤および／または二官能イソシアネート架橋剤との併用が、好ましい。 An isocyanate cross-linking agent (especially a bifunctional isocyanate cross-linking agent) and a peroxide cross-linking agent are preferable from the viewpoint of ensuring appropriate flexibility (thus flexibility) of the pressure-sensitive adhesive layer 20 . An isocyanate cross-linking agent (especially a trifunctional isocyanate cross-linking agent) is preferable from the viewpoint of ensuring the durability of the pressure-sensitive adhesive layer 20 . In the base polymer, difunctional isocyanate and peroxide crosslinkers form softer two-dimensional crosslinks, while trifunctional isocyanate crosslinkers form stronger three-dimensional crosslinks. From the viewpoint of achieving both durability and flexibility of the pressure-sensitive adhesive layer 20, it is preferable to use a trifunctional isocyanate cross-linking agent together with a peroxide cross-linking agent and/or a bifunctional isocyanate cross-linking agent.
　架橋剤の配合量は、粘着剤層２０の凝集力を確保する観点から、ベースポリマー１００質量部に対して、例えば０.０１質量部以上であり、好ましくは０.０５質量部以上、より好ましくは０.０７質量部以上である。粘着剤層２０において良好なタック性を確保する観点から、ベースポリマー１００質量部に対する架橋剤の配合量は、例えば１０質量部以下であり、好ましくは５質量部以下、より好ましくは３質量部以下である。 From the viewpoint of ensuring the cohesive strength of the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and more preferably 100 parts by mass of the base polymer. is 0.07 parts by mass or more. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 20, the amount of the cross-linking agent blended with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less. is.
　上記第２の方法では、モノマー成分（架橋構造を導入するための多官能モノマーと他のモノマーとを含む）は、一度で重合させてもよいし、多段階で重合させてもよい。多段階重合の方法では、まず、ベースポリマーを形成するための単官能モノマーを重合させ（予備重合）、これによって部分重合物（低重合度の重合物と未反応のモノマーとの混合物）を含有するプレポリマー組成物を調製する。次に、プレポリマー組成物に多官能モノマーを添加した後、部分重合物と多官能モノマーとを重合させる（本重合）。 In the second method, the monomer components (including the polyfunctional monomer for introducing the crosslinked structure and other monomers) may be polymerized at once or in multiple stages. In the multi-stage polymerization method, first, a monofunctional monomer for forming the base polymer is polymerized (prepolymerization), thereby containing a partially polymerized product (a mixture of a polymerized product with a low degree of polymerization and an unreacted monomer). A prepolymer composition is prepared. Next, after adding a polyfunctional monomer to the prepolymer composition, the partial polymer and the polyfunctional monomer are polymerized (main polymerization).
　多官能モノマーとしては、例えば、エチレン性不飽和二重結合を１分子中に２個以上含有する多官能（メタ）アクリレートが挙げられる。多官能モノマーとしては、活性エネルギー線重合（光重合）によって架橋構造を導入可能な観点から、多官能アクリレートが好ましい。 Examples of polyfunctional monomers include polyfunctional (meth)acrylates containing two or more ethylenically unsaturated double bonds in one molecule. As the polyfunctional monomer, a polyfunctional acrylate is preferable from the viewpoint that a crosslinked structure can be introduced by active energy ray polymerization (photopolymerization).
　多官能（メタ）アクリレートとしては、二官能（メタ）アクリレート、三官能（メタ）アクリレート、および、四官能以上の多官能（メタ）アクリレートが挙げられる。 Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional or higher polyfunctional (meth)acrylates.
　二官能（メタ）アクリレートとしては、例えば、エチレングリコールジ(メタ)アクリレート、ジエチレングリコールジ(メタ)アクリレート、トリエチレングリコールジ(メタ)アクリレート、テトラエチエレングルコールジメタクリレート、１,６－ヘキサンジオールジ(メタ)アクリレート、１,９－ノナンジオールジ(メタ)アクリレート、グリセリンジ(メタ)アクリレート、ネオペンチルグリコールジ(メタ)アクリレート、ステアリン酸変性ペンタエリスリトールジ(メタ)アクリレート、ジシクロペンテニルジアクリレート、ジ(メタ)アクリロイルイソシアヌレート、およびアルキレンオキサイド変性ビスフェノールジ(メタ)アクリレートが挙げられる。 Examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol di (meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, Examples include di(meth)acryloyl isocyanurate and alkylene oxide-modified bisphenol di(meth)acrylate.
　三官能（メタ）アクリレートとしては、例えば、トリメチロールプロパントリ(メタ)アクリレート、ペンタエリスリトールトリ(メタ)アクリレート、およびトリス（アクリロイルオキシエチル）イソシアヌレートが挙げられる。 Examples of trifunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate.
　四官能以上の多官能（メタ）アクリレートとしては、例えば、ジトリメチロールプロパンテトラ(メタ)アクリレート、ペンタエリスリトールテトラ(メタ)アクリレート、ジペンタエリスリトールモノヒドロキシペンタ(メタ)アクリレート、アルキル変性ジペンタエリスリトールペンタアクリレート、およびジペンタエリスリトールヘキサ(メタ)アクリレートが挙げられる。 Tetrafunctional or higher polyfunctional (meth)acrylates include, for example, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol pentaacrylate. , and dipentaerythritol hexa(meth)acrylate.
　多官能モノマーの分子量は、好ましくは１５００以下、より好ましくは１０００以下である。また、多官能モノマーの官能基当量（ｇ／ｅｑ）は、好ましくは５０以上、より好ましくは７０以上、更に好ましくは８０以上である。同官能基当量は、好ましくは５００以下、より好ましくは３００以下、更に好ましくは２００以下である。これら構成は、ベースポリマーにおいて架橋構造の導入により粘弾性（例えば、貯蔵弾性率Ｇ’および損失正接ｔａｎδ）を適切に調整する観点から好ましい。 The molecular weight of the polyfunctional monomer is preferably 1500 or less, more preferably 1000 or less. Also, the functional group equivalent (g/eq) of the polyfunctional monomer is preferably 50 or more, more preferably 70 or more, and even more preferably 80 or more. The functional group equivalent weight is preferably 500 or less, more preferably 300 or less, still more preferably 200 or less. These configurations are preferable from the viewpoint of appropriately adjusting viscoelasticity (for example, storage elastic modulus G' and loss tangent tan ?) by introducing a crosslinked structure in the base polymer.
　アクリルポリマーは、上述のモノマー成分を重合させることによって形成できる。重合方法としては、例えば、溶液重合、活性エネルギー線重合（例えばＵＶ重合）、塊状重合、および乳化重合が挙げられる。粘着剤層２０の透明性、耐水性、およびコストの観点から、溶液重合およびＵＶ重合が好ましい。溶液重合の溶媒としては、例えば、酢酸エチルおよびトルエンが用いられる。また、重合の開始剤としては、例えば、熱重合開始剤および光重合開始剤が用いられる。重合開始剤の使用量は、モノマー成分１００質量部に対して、例えば０.０５質量部以上であり、また、例えば１質量部以下である。 The acrylic polymer can be formed by polymerizing the above monomer components. Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization. Solution polymerization and UV polymerization are preferred from the viewpoints of transparency, water resistance, and cost of the pressure-sensitive adhesive layer 20 . Ethyl acetate and toluene, for example, are used as solvents for solution polymerization. Moreover, as a polymerization initiator, for example, a thermal polymerization initiator and a photopolymerization initiator are used. The amount of the polymerization initiator to be used is, for example, 0.05 parts by mass or more and, for example, 1 part by mass or less with respect to 100 parts by mass of the monomer component.
　熱重合開始剤としては、例えば、アゾ重合開始剤および過酸化物重合開始剤が挙げられる。アゾ重合開始剤としては、例えば、２,２'－アゾビスイソブチロニトリル、２,２'－アゾビス－２－メチルブチロニトリル、２,２'－アゾビス(２－メチルプロピオン酸)ジメチル、４,４'－アゾビス－４－シアノバレリアン酸、アゾビスイソバレロニトリル、２,２'－アゾビス(２－アミジノプロパン)ジヒドロクロライド、２,２'－アゾビス[２－(５－メチル－２－イミダゾリン－２－イル)プロパン]ジヒドロクロライド、２,２'－アゾビス(２－メチルプロピオンアミジン)二硫酸塩、および、２,２'－アゾビス(Ｎ,Ｎ'－ジメチレンイソブチルアミジン)ジヒドロクロライドが挙げられる。過酸化物重合開始剤としては、例えば、ジベンゾイルペルオキシド、ｔ－ブチルペルマレエ－ト、および過酸化ラウロイルが挙げられる。 Thermal polymerization initiators include, for example, azo polymerization initiators and peroxide polymerization initiators. Examples of azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2- imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride mentioned. Peroxide polymerization initiators include, for example, dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxide.
　光重合開始剤としては、例えば、ベンゾインエーテル光重合開始剤、アセトフェノン光重合開始剤、α－ケトール光重合開始剤、芳香族スルホニルクロリド光重合開始剤、光活性オキシム光重合開始剤、ベンゾイン光重合開始剤、ベンジル光重合開始剤、ベンゾフェノン光重合開始剤、ケタール光重合開始剤、チオキサントン光重合開始剤、およびアシルフォスフィンオキサイド光重合開始剤が挙げられる。 Examples of photopolymerization initiators include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, and benzoin photopolymerization initiators. Initiators include benzyl photoinitiators, benzophenone photoinitiators, ketal photoinitiators, thioxanthone photoinitiators, and acylphosphine oxide photoinitiators.
　重合においては、分子量調整等を目的として、連鎖移動剤および／または重合禁止剤（重合遅延剤）を用いてもよい。連鎖移動剤としては、α－チオグリセロール、ラウリルメルカプタン、グリシジルメルカプタン、メルカプト酢酸、２－メルカプトエタノール、チオグリコール酸、チオグルコール酸２－エチルヘキシル、２,３－ジメルカプト－１－プロパノール、およびα－メチルスチレン二量体が挙げられる。 In polymerization, a chain transfer agent and/or a polymerization inhibitor (polymerization retarder) may be used for the purpose of molecular weight adjustment. Chain transfer agents include α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and α-methylstyrene. Dimers are included.
　重合開始剤の種類および／または量の調整により、ベースポリマーの分子量を調整できる。例えば、ラジカル重合では、重合開始剤の量が多いほど、反応系のラジカル濃度が高いため、反応開始点の密度が高く、形成されるベースポリマーの分子量が小さくなる傾向がある。これに対し、重合開始剤の量が少ないほど、反応開始点の密度が低いためにポリマー鎖が伸長しやすく、形成されるベースポリマー分子量が大きくなる傾向がある。 The molecular weight of the base polymer can be adjusted by adjusting the type and/or amount of the polymerization initiator. For example, in radical polymerization, the larger the amount of the polymerization initiator, the higher the radical concentration in the reaction system, the higher the density of reaction initiation points, and the smaller the molecular weight of the base polymer formed. On the other hand, the smaller the amount of the polymerization initiator, the lower the density of the reaction initiation points, the easier it is for the polymer chain to extend, and the greater the molecular weight of the base polymer formed.
　アクリルポリマーの重量平均分子量は、粘着剤層２０における凝集力の確保の観点から、好ましくは１０万以上、より好ましくは３０万以上、更に好ましくは５０万以上である。同重量平均分子量は、好ましくは５００万以下、より好ましくは３００万以下、更に好ましくは２００万以下である。アクリルポリマーの重量平均分子量は、ゲル・パーミエーション・クロマトグラフ（ＧＰＣ）によって測定してポリスチレン換算により算出される。 The weight-average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more, from the viewpoint of securing the cohesive force in the pressure-sensitive adhesive layer 20 . The weight-average molecular weight is preferably 5 million or less, more preferably 3 million or less, still more preferably 2 million or less. The weight average molecular weight of the acrylic polymer is calculated by measuring by gel permeation chromatography (GPC) and converting to polystyrene.
　ベースポリマーのガラス転移温度（Ｔｇ）は、好ましくは０℃以下、より好ましくは－１０℃以下、更に好ましくは－２０℃以下である。同ガラス転移温度は、例えば－８０℃以上である。 The glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. The glass transition temperature is, for example, −80° C. or higher.
　ベースポリマーのガラス転移温度（Ｔｇ）については、下記のＦｏｘの式に基づき求められるガラス転移温度（理論値）を用いることができる。Ｆｏｘの式は、ポリマーのガラス転移温度Ｔｇと、当該ポリマーを構成するモノマーのホモポリマーのガラス転移温度Ｔｇｉとの関係式である。下記のＦｏｘの式において、Ｔｇはポリマーのガラス転移温度（℃）を表し、Ｗｉは当該ポリマーを構成するモノマーｉの重量分率を表し、Ｔｇｉは、モノマーｉから形成されるホモポリマーのガラス転移温度（℃）を示す。ホモポリマーのガラス転移温度については文献値を用いることができる。例えば、「Polymer Handbook」（第４版，John Wiley & Sons, Inc., 1999年）および「新高分子文庫７ 塗料用合成樹脂入門」（北岡協三著，高分子刊行会，1995年）には、各種のホモポリマーのガラス転移温度が挙げられている。一方、モノマーのホモポリマーのガラス転移温度については、特開２００７－５１２７１号公報に具体的に記載されている方法によって求めることも可能である。 For the glass transition temperature (Tg) of the base polymer, the glass transition temperature (theoretical value) obtained based on the following Fox formula can be used. The Fox equation is a relational expression between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of a homopolymer of monomers constituting the polymer. In the Fox formula below, Tg represents the glass transition temperature (° C.) of the polymer, Wi represents the weight fraction of the monomer i constituting the polymer, and Tgi represents the glass transition of the homopolymer formed from the monomer i. Indicates temperature (°C). Literature values can be used for the glass transition temperature of homopolymers. For example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Bunko 7 Introduction to Synthetic Resins for Paints" (Kyozo Kitaoka, Kobunshi Publications, 1995) , which lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of a homopolymer of a monomer can also be determined by the method specifically described in JP-A-2007-51271.
Ｆｏｘの式　　１／(２７３＋Ｔｇ)＝Σ［Ｗｉ／(２７３＋Ｔｇｉ)］ Fox's formula 1/(273+Tg)=Σ[Wi/(273+Tgi)]
　第１粘着剤組成物は、ベースポリマーに加えて、一種類または二種類以上のオリゴマーを含んでいてもよい。ベースポリマーとしてアクリルポリマーが用いられる場合、好ましくは、オリゴマーとしてアクリルオリゴマーが用いられる。アクリルオリゴマーは、（メタ）アクリル酸アルキルエステルを５０質量％以上の割合で含むモノマー成分の共重合体であり、重量平均分子量が例えば１０００以上３００００以下である。 The first adhesive composition may contain one or more oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, preferably an acrylic oligomer is used as the oligomer. The acrylic oligomer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.
　アクリルオリゴマーのガラス転移温度は、好ましくは６０℃以上、より好ましくは８０℃以上、更に好ましくは１００℃以上、特に好ましくは１１０℃以上である。アクリルオリゴマーのガラス転移温度は、例えば２００℃以下であり、好ましくは１８０℃以下、より好ましくは１６０℃以下である。架橋構造が導入された低Ｔｇのアクリルポリマー（ベースポリマー）と高Ｔｇのアクリルオリゴマーとの併用により、粘着剤層２０の接着力、特に高温での接着力を高められる。アクリルオリゴマーのガラス転移温度は、上記のＦｏｘの式により算出される。 The glass transition temperature of the acrylic oligomer is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 110°C or higher. The glass transition temperature of the acrylic oligomer is, for example, 200° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower. The combined use of a low-Tg acrylic polymer (base polymer) introduced with a cross-linked structure and a high-Tg acrylic oligomer can increase the adhesive strength of the pressure-sensitive adhesive layer 20, especially at high temperatures. The glass transition temperature of the acrylic oligomer is calculated by the above Fox formula.
　ガラス転移温度が６０℃以上のアクリルオリゴマーは、好ましくは、鎖状アルキル基を有する（メタ）アクリル酸アルキルエステル（鎖状アルキル（メタ）アクリレート）と、脂環式アルキル基を有する（メタ）アクリル酸アルキルエステル（脂環式アルキル（メタ）アクリレート）とを含むモノマー成分の重合体である。これら（メタ）アクリル酸アルキルエステルの具体例としては、例えば、アクリルポリマーのモノマー成分として上記した（メタ）アクリル酸アルキルエステルが挙げられる。 The acrylic oligomer having a glass transition temperature of 60° C. or higher is preferably a (meth)acrylic acid alkyl ester having a chain alkyl group (chain alkyl (meth)acrylate) and a (meth)acrylic acid having an alicyclic alkyl group. It is a polymer of a monomer component containing an acid alkyl ester (alicyclic alkyl (meth)acrylate). Specific examples of these (meth)acrylic acid alkyl esters include, for example, the (meth)acrylic acid alkyl esters described above as the monomer component of the acrylic polymer.
　鎖状アルキル（メタ）アクリレートとしては、ガラス転移温度が高く、ベースポリマーとの相溶性に優れることから、メタクリル酸メチルが好ましい。脂環式アルキル（メタ）アクリレートとしては、アクリル酸ジシクロペンタニル、メタクリル酸ジシクロペンタニル、アクリル酸シクロヘキシル、およびメタクリル酸シクロヘキシルが好ましい。すなわち、アクリルオリゴマーは、アクリル酸ジシクロペンタニル、メタクリル酸ジシクロペンタニル、アクリル酸シクロヘキシル、およびメタクリル酸シクロヘキシルからなる群より選択される１種以上と、メタクリル酸メチルとを含むモノマー成分の重合体であるのが好ましい。 As the chain alkyl (meth)acrylate, methyl methacrylate is preferable because it has a high glass transition temperature and excellent compatibility with the base polymer. Preferred alicyclic alkyl (meth)acrylates are dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate. That is, the acrylic oligomer is a monomer component containing methyl methacrylate and at least one selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate. A coalescence is preferred.
　アクリルオリゴマーのモノマー成分における脂環式アルキル（メタ）アクリレートの割合は、好ましくは１０重量％以上、より好ましくは２０重量％以上、更に好ましくは３０重量％以上である。同割合は、好ましくは９０重量％以下、より好ましくは８０重量％以下、更に好ましくは７０重量％以下である。アクリルオリゴマーのモノマー成分における鎖状アルキル（メタ）アクリレートの割合は、好ましくは９０重量％以下、より好ましくは８０重量％以下、更に好ましくは７０重量％以下である。同割合は、好ましくは１０重量％以上、より好ましくは２０重量％以上、更に好ましくは３０重量％以上である。 The proportion of the alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more. The same ratio is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less. The proportion of chain alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less. The ratio is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more.
　アクリルオリゴマーの重量平均分子量は、好ましくは１０００以上、より好ましくは１５００以上、更に好ましくは２０００以上である。同分子量は、好ましくは３００００以下、より好ましくは１００００以下、更に好ましくは８０００以下である。このようなアクリルオリゴマーの分子量範囲は、粘着剤層２０の接着力および接着保持力を確保するのに好ましい。 The weight average molecular weight of the acrylic oligomer is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. The molecular weight is preferably 30,000 or less, more preferably 10,000 or less, still more preferably 8,000 or less. Such a molecular weight range of the acrylic oligomer is preferable for ensuring the adhesive strength and adhesive holding power of the pressure-sensitive adhesive layer 20 .
　アクリルオリゴマーは、当該アクリルオリゴマーのモノマー成分を重合することによって得られる。重合方法としては、例えば、溶液重合、活性エネルギー線重合（例えばＵＶ重合）、塊状重合、および乳化重合が挙げられる。アクリルオリゴマーの重合においては、重合開始剤を用いてもよく、分子量の調整を目的として連鎖移動剤を用いてもよい。 The acrylic oligomer is obtained by polymerizing the monomer component of the acrylic oligomer. Polymerization methods include, for example, solution polymerization, active energy ray polymerization (eg, UV polymerization), bulk polymerization, and emulsion polymerization. In the polymerization of the acrylic oligomer, a polymerization initiator may be used, and a chain transfer agent may be used for the purpose of adjusting the molecular weight.
　粘着剤層２０におけるアクリルオリゴマーの含有量は、粘着剤層２０の接着力を充分に高めるためには、ベースポリマー１００質量部に対して、好ましくは０.５質量部以上、より好ましくは０.８質量部以上、更に好ましくは１質量部以上である。一方、粘着剤層２０の透明性の確保の観点からは、粘着剤層２０におけるアクリルオリゴマーの含有量は、ベースポリマー１００質量部に対して、好ましくは５質量部以下、より好ましくは４質量部以下、更に好ましくは３質量部以下である。粘着剤層２０においては、アクリルオリゴマーの含有量が大きすぎる場合、当該アクリルオリゴマーの相溶性の低下に起因して、ヘイズが上昇して透明性が低下する傾向がある。 The content of the acrylic oligomer in the pressure-sensitive adhesive layer 20 is preferably 0.5 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the base polymer, in order to sufficiently increase the adhesive strength of the pressure-sensitive adhesive layer 20 . It is 8 parts by mass or more, more preferably 1 part by mass or more. On the other hand, from the viewpoint of ensuring the transparency of the adhesive layer 20, the content of the acrylic oligomer in the adhesive layer 20 is preferably 5 parts by mass or less, more preferably 4 parts by mass with respect to 100 parts by mass of the base polymer. 3 parts by mass or less, more preferably 3 parts by mass or less. In the pressure-sensitive adhesive layer 20, when the content of the acrylic oligomer is too large, the haze tends to increase and the transparency tends to decrease due to the decrease in compatibility of the acrylic oligomer.
　第１粘着剤組成物は、シランカップリング剤を含有してもよい。第１粘着剤組成物におけるシランカップリング剤の含有量は、ベースポリマー１００質量部に対して、好ましくは０.１質量部以上、より好ましくは０.２質量部以上である。同含有量は、好ましくは５質量部以下、より好ましくは３質量部以下である。 The first adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the first pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.
　第１粘着剤組成物は、必要に応じて他の成分を含有してもよい。他の成分としては、例えば、粘着付与剤、可塑剤、軟化剤、劣化防止剤、充填剤、着色剤、紫外線吸収剤、酸化防止剤、界面活性剤、および帯電防止剤が挙げられる。 The first adhesive composition may contain other components as necessary. Other ingredients include, for example, tackifiers, plasticizers, softeners, antidegradants, fillers, colorants, UV absorbers, antioxidants, surfactants, and antistatic agents.
　粘着剤層２０のヘイズは、好ましくは３％以下、より好ましくは２％以下、より好ましくは１％以下である。粘着剤層２０のヘイズは、ＪＩＳ Ｋ７１３６（２０００年）に準拠して、ヘイズメーターを使用して測定できる。ヘイズメーターとしては、例えば、日本電色工業社製の「ＮＤＨ２０００」、および、村上色彩技術研究所社製の「ＨＭ-１５０型」が挙げられる。 The haze of the adhesive layer 20 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less. The haze of the pressure-sensitive adhesive layer 20 can be measured using a haze meter according to JIS K7136 (2000). Examples of the haze meter include "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd. and "HM-150 type" manufactured by Murakami Color Research Laboratory.
　粘着剤層２０の全光線透過率は、好ましくは６０％以上、より好ましくは８０％以上、更に好ましくは８５％以上である。粘着剤層２０の全光線透過率は、例えば１００％以下である。粘着剤層２０の全光線透過率は、ＪＩＳ Ｋ ７３７５（２００８年）に準拠して、測定できる。 The total light transmittance of the adhesive layer 20 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher. The total light transmittance of the adhesive layer 20 is, for example, 100% or less. The total light transmittance of the adhesive layer 20 can be measured according to JIS K 7375 (2008).
　粘着剤層３０は、第２粘着剤組成物から形成された感圧粘着剤層である。粘着剤層３０は、透明性を有する。第２粘着剤組成物は、少なくともベースポリマーを含有する。第２粘着剤組成物に含有されるベースポリマーとしては、例えば、第１粘着剤組成物に関して上記したベースポリマーが挙げられる。第１粘着剤組成物中のベースポリマーと、第２粘着剤組成物中のベースポリマーとは、同じであってもよいし、異なってもよい。第２粘着剤組成物は、ベースポリマー以外の成分を含有してもよい。第２粘着剤組成物に含有される同成分としては、例えば、第１粘着剤組成物に関して上記した、ベースポリマー以外の成分が挙げられる。第１粘着剤組成物の組成と第２粘着剤組成物の組成は、同じであってもよいし、異なってもよい。上述の剥離力Ｆ１,Ｆ２の調整の観点からは、第１粘着剤組成物の組成と第２粘着剤組成物の組成とは異なるのが好ましい。 The adhesive layer 30 is a pressure-sensitive adhesive layer formed from the second adhesive composition. The adhesive layer 30 has transparency. The second PSA composition contains at least a base polymer. Examples of the base polymer contained in the second pressure-sensitive adhesive composition include the base polymers described above with respect to the first pressure-sensitive adhesive composition. The base polymer in the first PSA composition and the base polymer in the second PSA composition may be the same or different. The second PSA composition may contain components other than the base polymer. Examples of the components contained in the second pressure-sensitive adhesive composition include the components other than the base polymer described above for the first pressure-sensitive adhesive composition. The composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition may be the same or different. From the viewpoint of adjusting the peeling forces F1 and F2 described above, it is preferable that the composition of the first pressure-sensitive adhesive composition and the composition of the second pressure-sensitive adhesive composition are different.
　粘着剤層３０のヘイズは、好ましくは３％以下、より好ましくは２％以下、より好ましくは１％以下である。粘着剤層３０のヘイズは、ＪＩＳ Ｋ７１３６（２０００年）に準拠して、ヘイズメーターを使用して測定できる。 The haze of the adhesive layer 30 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less. The haze of the adhesive layer 30 can be measured using a haze meter according to JIS K7136 (2000).
　粘着剤層３０の全光線透過率は、好ましくは６０％以上、より好ましくは８０％以上、更に好ましくは８５％以上である。粘着剤層３０の全光線透過率は、例えば１００％以下である。粘着剤層３０の全光線透過率は、ＪＩＳ Ｋ ７３７５（２００８年）に準拠して、測定できる。 The total light transmittance of the adhesive layer 30 is preferably 60% or higher, more preferably 80% or higher, and even more preferably 85% or higher. The total light transmittance of the adhesive layer 30 is, for example, 100% or less. The total light transmittance of the adhesive layer 30 can be measured according to JIS K 7375 (2008).
　カバーフィルム４０としては、例えば、可撓性を有するプラスチックフィルムが挙げられる。当該プラスチックフィルムとしては、例えば、ポリエチレンテレフタレートフィルム、ポリエチレンフィルム、ポリプロピレンフィルム、およびポリエステルフィルムが挙げられる。カバーフィルム４０における粘着剤層２０側の表面は、好ましくは剥離処理されている。剥離処理としては、例えば、シリコーン剥離処理およびフッ素剥離処理が挙げられる（後記の剥離処理についても同様である）。剥離処理の有無、種類の選択、および条件の調整により、粘着剤層２０からのカバーフィルム４０の剥離に関する上述の剥離力Ｆ１を調整できる。 Examples of the cover film 40 include a flexible plastic film. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. The surface of the cover film 40 on the pressure-sensitive adhesive layer 20 side is preferably subjected to release treatment. Examples of the release treatment include silicone release treatment and fluorine release treatment (the same applies to the release treatment described below). The peeling force F1 for peeling the cover film 40 from the pressure-sensitive adhesive layer 20 can be adjusted by adjusting the presence or absence of the peeling treatment, the selection of the type, and the conditions.
　カバーフィルム５０としては、例えば、カバーフィルム４０に関して上記したプラスチックフィルムが挙げられる。カバーフィルム５０における粘着剤層３０側の表面は、好ましくは剥離処理されている。剥離処理の有無、種類の選択、および条件の調整により、粘着剤層３０からのカバーフィルム５０の剥離に関する上述の剥離力Ｆ２を調整できる。 Examples of the cover film 50 include the plastic films described above with respect to the cover film 40 . The surface of the cover film 50 on the pressure-sensitive adhesive layer 30 side is preferably subjected to release treatment. The peeling force F2 for peeling the cover film 50 from the pressure-sensitive adhesive layer 30 can be adjusted by the presence or absence of the peeling treatment, selection of the type, and adjustment of the conditions.
　光学フィルムＸ１は、例えば、次のようにして製造できる。 The optical film X1 can be produced, for example, as follows.
　まず、光学フィルム１０と、カバーフィルム４０付きの粘着剤層２０と、カバーフィルム５０付き粘着剤層３０とを用意する（用意工程）。 First, the optical film 10, the adhesive layer 20 with the cover film 40, and the adhesive layer 30 with the cover film 50 are prepared (preparation step).
　カバーフィルム４０付き粘着剤層２０は、カバーフィルム４０上に第１粘着剤組成物（ワニス）を塗布して塗膜を形成した後、当該塗膜を乾燥することによって形成できる。第１粘着剤組成物の塗布方法としては、例えば、ロールコート、キスロールコート、グラビアコート、リバースコート、ロールブラッシュ、スプレーコート、ディップロールコート、バーコート、ナイフコート、エアーナイフコート、カーテンコート、リップコート、およびダイコートが挙げられる（他の粘着剤組成物の後記の塗布の方法についても同様である）。カバーフィルム４０上の粘着剤層２０の上に更に別の剥離フィルムを積層してもよい。この剥離フィルムは、光学フィルム１０と粘着剤層２０との貼り合わせの前に剥離される。 The adhesive layer 20 with the cover film 40 can be formed by applying the first adhesive composition (varnish) on the cover film 40 to form a coating film, and then drying the coating film. Examples of the method of applying the first pressure-sensitive adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, Lip coating and die coating can be mentioned (the same applies to other methods of applying other pressure-sensitive adhesive compositions described below). Another release film may be laminated on the adhesive layer 20 on the cover film 40 . This peeling film is peeled off before bonding the optical film 10 and the pressure-sensitive adhesive layer 20 together.
　カバーフィルム５０付き粘着剤層３０は、カバーフィルム５０上に第２粘着剤組成物（ワニス）を塗布して塗膜を形成した後、当該塗膜を乾燥することによって形成できる。カバーフィルム５０上の粘着剤層３０の上に更に別の剥離フィルムを積層してもよい。この剥離フィルムは、光学フィルム１０と粘着剤層３０との貼り合わせの前に剥離される。 The adhesive layer 30 with the cover film 50 can be formed by applying the second adhesive composition (varnish) on the cover film 50 to form a coating film, and then drying the coating film. Another release film may be laminated on the adhesive layer 30 on the cover film 50 . This peeling film is peeled off before bonding the optical film 10 and the adhesive layer 30 together.
　次に、光学フィルム１０の第１面１１と、カバーフィルム４０付き粘着剤層２０の粘着剤層２０側とを、貼り合わせる（第１貼合せ工程）。次に、光学フィルム１０の第２面１２と、カバーフィルム５０付き粘着剤層３０の粘着剤層３０側とを、貼り合わせる（第２貼合せ工程）。好ましくは、これら貼り合わせの前に、光学フィルム１０の第１面１１および第２面１２と、カバーフィルム４０付き粘着剤層２０の露出面と、カバーフィルム５０付き粘着剤層３０の露出面とは、プラズマ処理される。 Next, the first surface 11 of the optical film 10 and the pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 with the cover film 40 are pasted together (first pasting step). Next, the second surface 12 of the optical film 10 and the pressure-sensitive adhesive layer 30 side of the pressure-sensitive adhesive layer 30 with the cover film 50 are pasted together (second pasting step). Preferably, the first surface 11 and the second surface 12 of the optical film 10, the exposed surface of the pressure-sensitive adhesive layer 20 with the cover film 40, and the exposed surface of the pressure-sensitive adhesive layer 30 with the cover film 50 are preferably attached before the bonding. is plasma treated.
　以上のようにして、上述の光学フィルムＸ１（カバーフィルム付き光学フィルム）を製造できる。光学フィルムＸ１は、打ち抜き加工によって成形してもよい。打ち抜き加工においては、例えば、打抜き加工機およびトムソン刃を使用する。 As described above, the optical film X1 (optical film with cover film) can be manufactured. The optical film X1 may be formed by punching. In punching, for example, a punching machine and a Thomson blade are used.
　図２Ａから図２Ｄは、光学フィルムＸ１の使用方法の一例を表す。 2A to 2D show an example of how to use the optical film X1.
　本方法では、まず、図２Ａに示すように、光学フィルムＸ１の粘着剤層２０からカバーフィルム４０を剥離する。例えば、光学フィルムＸ１のカバーフィルム５０側をワークテーブル上に固定した状態で、カバーフィルム４０の端部に力を作用させて、粘着剤層２０からカバーフィルム４０を剥離する。これにより、粘着剤層２０の粘着面２１が露出する。本工程において、光学フィルムＸ１は、上述のように、粘着剤層２０,３０付きの薄い光学フィルム１０から、カバーフィルム５０の剥離と光学フィルム１０端部のクラックとを抑制しつつ、カバーフィルム４０を剥離するのに適する。 In this method, first, as shown in FIG. 2A, the cover film 40 is peeled off from the adhesive layer 20 of the optical film X1. For example, while the cover film 50 side of the optical film X1 is fixed on a work table, force is applied to the edge of the cover film 40 to separate the cover film 40 from the adhesive layer 20 . Thereby, the adhesive surface 21 of the adhesive layer 20 is exposed. In this step, the optical film X1 is formed from the thin optical film 10 with the pressure-sensitive adhesive layers 20 and 30 as described above, while suppressing peeling of the cover film 50 and cracks at the edges of the optical film 10. suitable for stripping.
　次に、図２Ｂに示すように、粘着剤層２０を介して光学フィルム１０と第１部材Ｍ１（第１被着体）とを接合する。第１部材Ｍ１は、例えば、フレキシブルパネルが有する積層構造中の一要素である。当該要素としては、例えば、画素パネル、タッチパネル、および透明カバーフィルムが挙げられる（後記の第２部材Ｍ２についても同様である）。 Next, as shown in FIG. 2B, the optical film 10 and the first member M1 (first adherend) are bonded with the adhesive layer 20 interposed therebetween. The first member M1 is, for example, one element in the laminated structure of the flexible panel. Examples of such elements include a pixel panel, a touch panel, and a transparent cover film (the same applies to the second member M2 described later).
　次に、図２Ｃに示すように、粘着剤層３０からカバーフィルム５０を剥離する。これにより、粘着剤層３０の粘着面３１が露出する。 Next, the cover film 50 is peeled off from the adhesive layer 30 as shown in FIG. 2C. Thereby, the adhesive surface 31 of the adhesive layer 30 is exposed.
　次に、図２Ｄに示すように、粘着剤層３０を介して光学フィルム１０と第２部材Ｍ２（第２被着体）とを接合する。 Next, as shown in FIG. 2D, the optical film 10 and the second member M2 (second adherend) are bonded with the adhesive layer 30 interposed therebetween.
　例えばフレキシブルパネルの製造過程において、光学フィルムＸ１は以上のように使用される。 For example, in the manufacturing process of flexible panels, the optical film X1 is used as described above.
　本発明のカバーフィルム付き光学フィルムの第２の実施形態としての光学フィルムＸ２は、図３に示すように、光学フィルム１０と、粘着剤層２０（第１粘着剤層）と、粘着剤層３０（第２粘着剤層）と、カバーフィルム４０（第１カバーフィルム）と、カバーフィルム６０（第２カバーフィルム）とを備える。光学フィルムＸ２は、所定の厚さのシート形状を有し、厚さ方向Ｔと直交する方向（面方向）に広がる。光学フィルムＸ２は、具体的には、カバーフィルム６０と、粘着剤層３０と、光学フィルム１０と、粘着剤層２０と、カバーフィルム４０とを、厚さ方向Ｔに順に備える。 Optical film X2 as a second embodiment of the optical film with a cover film of the present invention comprises, as shown in FIG. (second adhesive layer), cover film 40 (first cover film), and cover film 60 (second cover film). The optical film X2 has a sheet shape with a predetermined thickness and spreads in a direction orthogonal to the thickness direction T (surface direction). Specifically, the optical film X2 includes a cover film 60, an adhesive layer 30, an optical film 10, an adhesive layer 20, and a cover film 40 in the thickness direction T in this order.
　光学フィルムＸ２は、粘着剤層付き光学フィルムＹ１およびカバーフィルム４０,５０に代えて、粘着剤層付き光学フィルムＹ２および粘着剤層３０付きカバーフィルム６０を備える点で、光学フィルムＸ１と異なる。粘着剤層付き光学フィルムＹ２は、粘着剤層３０を備えないこと以外は、粘着剤層付き光学フィルムＹ１と同じである。粘着剤層３０付きカバーフィルム６０は、カバーフィルム６０と、当該カバーフィルム６０の厚さ方向Ｔの一方面上の粘着剤層３０とを備える。カバーフィルム６０は、可撓性を有する透明な表面保護フィルムである。粘着剤層３０は、粘着剤層付き光学フィルムＹ２の光学フィルム１０の第２面１２に接する。粘着剤層３０付きカバーフィルム６０は、粘着剤層付き光学フィルムＹ２における第２面１２上に剥離可能に配置された粘着剤層付き表面保護フィルムである。他の構成については、光学フィルムＸ２は光学フィルムＸ１と同じである。 The optical film X2 differs from the optical film X1 in that it includes an optical film Y2 with an adhesive layer and a cover film 60 with an adhesive layer 30 instead of the optical film Y1 with an adhesive layer and the cover films 40 and 50. The pressure-sensitive adhesive layer-attached optical film Y2 is the same as the pressure-sensitive adhesive layer-attached optical film Y1 except that the pressure-sensitive adhesive layer 30 is not provided. The cover film 60 with the adhesive layer 30 includes the cover film 60 and the adhesive layer 30 on one side of the cover film 60 in the thickness direction T. The cover film 60 is a flexible, transparent surface protection film. The adhesive layer 30 contacts the second surface 12 of the optical film 10 of the optical film Y2 with an adhesive layer. The cover film 60 with the adhesive layer 30 is a surface protective film with an adhesive layer that is detachably arranged on the second surface 12 of the optical film Y2 with the adhesive layer. Other configurations of the optical film X2 are the same as those of the optical film X1.
　このような光学フィルムＸ２は、フォルダブルディスプレイパネルの製造過程において、同パネルの積層構造に組み込まれる粘着剤層付き光学フィルムＹ２の供給材として用いられる。カバーフィルム４０は、フォルダブルディスプレイパネルの製造過程において、所定のタイミングで粘着剤層付き光学フィルムＹ２から剥がされる。粘着剤層３０付きカバーフィルム６０は、粘着剤層付き光学フィルムＹ２から剥がされなくてもよい。 Such an optical film X2 is used as a supply material for the pressure-sensitive adhesive layer-attached optical film Y2 incorporated in the laminated structure of the foldable display panel in the manufacturing process of the same panel. The cover film 40 is peeled off from the pressure-sensitive adhesive layer-attached optical film Y2 at a predetermined timing during the manufacturing process of the foldable display panel. The cover film 60 with the adhesive layer 30 may not be peeled off from the optical film Y2 with the adhesive layer.
　光学フィルムＸ２において、光学フィルム１０は、１００μｍ以下の厚さＨ１（第１厚さ）を有する。光学フィルム１０および粘着剤層付き光学フィルムＹ２においてフレキシブルパネルに適した可撓性を確保する観点から、厚さＨ１は、好ましくは８０μｍ以下、より好ましくは６０μｍ以下、更に好ましくは４０μｍ以下である。光学フィルム１０の強度の観点から、厚さＨ１は、好ましくは３μｍ以上、より好ましくは５μｍ以上、更に好ましくは１０μｍ以上である。 In the optical film X2, the optical film 10 has a thickness H1 (first thickness) of 100 μm or less. From the viewpoint of ensuring flexibility suitable for flexible panels in the optical film 10 and the pressure-sensitive adhesive layer-attached optical film Y2, the thickness H1 is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less. From the viewpoint of strength of the optical film 10, the thickness H1 is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more.
　粘着剤層２０は、５μｍ以上１００μｍ以下の厚さＨ２（第２厚さ）を有する。粘着剤層２０における充分な粘着力を確保する観点から、厚さＨ２は、好ましくは１０μｍ以上、より好ましくは２０μｍ以上、更に好ましくは３０μｍ以上である。粘着剤層２０からカバーフィルム４０を剥離するための剥離力を抑制する観点から、厚さＨ２は、好ましくは９０μｍ以下、より好ましくは８０μｍ以下、更に好ましくは７０μｍ以下である。 The adhesive layer 20 has a thickness H2 (second thickness) of 5 μm or more and 100 μm or less. From the viewpoint of ensuring sufficient adhesive strength in the adhesive layer 20, the thickness H2 is preferably 10 µm or more, more preferably 20 µm or more, and even more preferably 30 µm or more. From the viewpoint of suppressing the peeling force for peeling the cover film 40 from the adhesive layer 20, the thickness H2 is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less.
　粘着剤層２０は、２５℃において２０ｋＰａ以上１００ｋＰａ以下のせん断貯蔵弾性率Ｍ１（第１せん断貯蔵弾性率）を有する。粘着剤層２０の粘着力と、当該粘着剤層２０からカバーフィルム４０を剥離するための剥離力とのバランスの観点から、せん断貯蔵弾性率Ｍ１は、好ましくは３０ｋＰａ以上、より好ましくは４０ｋＰａ以上、更に好ましくは４５ｋＰａ以上であり、また、好ましくは９０ｋＰａ以下、より好ましくは８０ｋＰａ以下、更に好ましくは７５ｋＰａ以下である。せん断貯蔵弾性率Ｍ１は、動的粘弾性測定装置によって測定できる。その測定において、測定モードをねじりモードとし、測定温度範囲を－５０℃～１５０℃とし、昇温速度を５℃/分とし、周波数を１Ｈｚとする（後述のせん断貯蔵弾性率Ｍ２の測定においても同様である）。せん断貯蔵弾性率Ｍ１の調整方法としては、例えば、粘着剤層２０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整、並びに、前記ベースポリマーを架橋する架橋剤の種類の選択および配合量の調整が挙げられる。 The adhesive layer 20 has a shear storage modulus M1 (first shear storage modulus) of 20 kPa or more and 100 kPa or less at 25°C. From the viewpoint of the balance between the adhesive force of the adhesive layer 20 and the peeling force for peeling the cover film 40 from the adhesive layer 20, the shear storage elastic modulus M1 is preferably 30 kPa or more, more preferably 40 kPa or more, It is more preferably 45 kPa or more, preferably 90 kPa or less, more preferably 80 kPa or less, and still more preferably 75 kPa or less. The shear storage modulus M1 can be measured with a dynamic viscoelasticity measuring device. In the measurement, the measurement mode is the torsion mode, the measurement temperature range is -50 ° C. to 150 ° C., the temperature increase rate is 5 ° C./min, and the frequency is 1 Hz (also in the measurement of the shear storage elastic modulus M2 described later) similar). Methods for adjusting the shear storage modulus M1 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 20, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
　粘着剤層３０は、５μｍ以上３０μｍ以下の厚さＨ３（第３厚さ）を有する。粘着剤層３０における充分な粘着力を確保する観点から、厚さＨ３は、好ましくは７μｍ以上、より好ましくは１０μｍ以上である。光学フィルム１０から粘着剤層３０付きカバーフィルム６０を剥離するための剥離力を抑制する観点から、厚さＨ３は、好ましくは２５μｍ以下、より好ましくは２０μｍ以下である。 The adhesive layer 30 has a thickness H3 (third thickness) of 5 μm or more and 30 μm or less. From the viewpoint of ensuring sufficient adhesive strength in the adhesive layer 30, the thickness H3 is preferably 7 μm or more, more preferably 10 μm or more. The thickness H3 is preferably 25 μm or less, more preferably 20 μm or less, from the viewpoint of suppressing the peeling force for peeling the cover film 60 with the pressure-sensitive adhesive layer 30 from the optical film 10 .
　粘着剤層３０は、２５℃において１５０ｋＰａ以上のせん断貯蔵弾性率Ｍ２（第２せん断貯蔵弾性率）を有する。粘着剤層３０の粘着力と、光学フィルム１０から粘着剤層３０付きカバーフィルム６０を剥離するための剥離力とのバランスの観点から、せん断貯蔵弾性率Ｍ２は、好ましくは５００ｋＰａ以上、より好ましくは１５００ｋＰａ以上、更に好ましくは２０００ｋＰａ以上であり、また、好ましくは５０００ｋＰａ以下、より好ましくは４５００ｋＰａ以下、更に好ましくは４０００ｋＰａ以下である。せん断貯蔵弾性率Ｍ２の調整方法としては、例えば、粘着剤層３０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整、並びに、前記ベースポリマーを架橋する架橋剤の種類の選択および配合量の調整が挙げられる。 The adhesive layer 30 has a shear storage modulus M2 (second shear storage modulus) of 150 kPa or more at 25°C. From the viewpoint of the balance between the adhesive force of the adhesive layer 30 and the peeling force for peeling the cover film 60 with the adhesive layer 30 from the optical film 10, the shear storage elastic modulus M2 is preferably 500 kPa or more, more preferably It is 1500 kPa or more, more preferably 2000 kPa or more, and preferably 5000 kPa or less, more preferably 4500 kPa or less, and still more preferably 4000 kPa or less. Methods for adjusting the shear storage modulus M2 include, for example, selection of the type of base polymer for the adhesive layer 30, adjustment of the molecular weight, adjustment of the compounding amount, and selection of the type of cross-linking agent that cross-links the base polymer. Selection and adjustment of compounding amount are included.
　カバーフィルム４０は、４０μｍ以上８０μｍ以下の厚さＨ４（第４厚さ）を有する。カバーフィルム４０の可撓性を確保する観点から、厚さＨ４は、好ましくは７５μｍ以下、より好ましくは７０μｍ以下である。カバーフィルム４０の強度の観点から、厚さＨ４は、好ましくは４５μｍ以上、より好ましくは４８μｍ以上、更に好ましくは５０μｍ以上である。 The cover film 40 has a thickness H4 (fourth thickness) of 40 µm or more and 80 µm or less. From the viewpoint of ensuring the flexibility of the cover film 40, the thickness H4 is preferably 75 μm or less, more preferably 70 μm or less. From the viewpoint of strength of the cover film 40, the thickness H4 is preferably 45 μm or more, more preferably 48 μm or more, and even more preferably 50 μm or more.
　カバーフィルム６０は、４０μｍ以上８０μｍ以下の厚さＨ５（第５厚さ）を有する。カバーフィルム６０の可撓性を確保する観点、および、カバーフィルム剥離時における光学フィルム１０端部のクラック抑制の観点から、厚さＨ５は、好ましくは７５μｍ以下、より好ましくは７０μｍ以下である。カバーフィルム４０の強度の観点から、厚さＨ５は、好ましくは４５μｍ以上、より好ましくは４８μｍ以上、更に好ましくは５０μｍ以上である。 The cover film 60 has a thickness H5 (fifth thickness) of 40 µm or more and 80 µm or less. The thickness H5 is preferably 75 μm or less, more preferably 70 μm or less, from the viewpoint of ensuring the flexibility of the cover film 60 and from the viewpoint of suppressing cracks at the edges of the optical film 10 when the cover film is peeled off. From the viewpoint of strength of the cover film 40, the thickness H5 is preferably 45 μm or more, more preferably 48 μm or more, and even more preferably 50 μm or more.
　厚さＨ５に対する上述の厚さＨ４の比率（Ｈ４／Ｈ５）は、本実施形態では、１以上である。カバーフィルム４０の剥離時に粘着剤層３０付きカバーフィルム６０の剥離を抑制する観点から、比率（Ｈ４／Ｈ５）は、好ましくは１.１以上、より好ましくは１.２以上である。比率（Ｈ４／Ｈ５）は、例えば５以下である。 The ratio (H4/H5) of the thickness H4 to the thickness H5 is 1 or more in this embodiment. From the viewpoint of suppressing peeling of the cover film 60 with the adhesive layer 30 when the cover film 40 is peeled off, the ratio (H4/H5) is preferably 1.1 or more, more preferably 1.2 or more. The ratio (H4/H5) is, for example, 5 or less.
　カバーフィルム４０を粘着剤層２０から剥離するための剥離力Ｆ１（第１剥離力）の、粘着剤層３０付きカバーフィルム６０を光学フィルム１０から剥離するための剥離力Ｆ２（第２剥離力）に対する比率（Ｆ１／Ｆ２）は、０.９以下である。カバーフィルム４０の剥離時に粘着剤層３０付きカバーフィルム６０の剥離を抑制する観点から、比率（Ｆ１／Ｆ２）は、好ましくは０.８以下、より好ましくは０.７以下、更に好ましくは０.６以下である。比率（Ｆ１／Ｆ２）は、例えば０.１以上である。剥離力Ｆ１および剥離力Ｆ２は、それぞれ、測定温度２５℃、剥離角度１８０°、および引張速度３００ｍｍ／分での条件での剥離試験において測定される。 The peeling force F1 (first peeling force) for peeling the cover film 40 from the adhesive layer 20, and the peeling force F2 (second peeling force) for peeling the cover film 60 with the adhesive layer 30 from the optical film 10 ratio (F1/F2) to is 0.9 or less. From the viewpoint of suppressing peeling of the cover film 60 with the adhesive layer 30 when the cover film 40 is peeled off, the ratio (F1/F2) is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.7. 6 or less. The ratio (F1/F2) is, for example, 0.1 or more. The peel force F1 and the peel force F2 are each measured in a peel test under conditions of a measurement temperature of 25° C., a peel angle of 180°, and a tensile speed of 300 mm/min.
　剥離力Ｆ１は、１０ｇｆ/２５ｍｍ以下である。粘着剤層２０からのカバーフィルム４０の剥離時に良好な剥離作業を確保する観点から、剥離力Ｆ１は、好ましくは７ｇｆ/２５ｍｍ以下、より好ましくは５ｇｆ/２５ｍｍ以下、更に好ましくは３ｇｆ/２５ｍｍ以下、特に好ましくは２.５ｇｆ/２５ｍｍ以下である。粘着剤層２０からのカバーフィルム４０の意図しない剥離を抑制する観点から、剥離力Ｆ１は、好ましくは０.１ｇｆ/２５ｍｍ以上、より好ましくは０.３ｇｆ/２５ｍｍ以上、更に好ましくは０.５ｇｆ/２５ｍｍ以上である。剥離力Ｆ１の調整方法としては、例えば、粘着剤層２０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整が挙げられる。ベースポリマーの種類の選択には、ベースポリマーにおける主鎖の種類（構成）の選択、並びに、官能基の種類の選択および量の調整が含まれる（後記の、ベースポリマーの種類の選択についても、同様である）。剥離力Ｆ１の調整方法としては、粘着剤層２０におけるベースポリマー以外の成分の種類の選択、および、当該成分の配合量の調整も挙げられる。当該成分としては、架橋剤、シランカップリング剤、およびオリゴマーが挙げられる。 The peeling force F1 is 10 gf/25 mm or less. From the viewpoint of ensuring a good peeling operation when peeling the cover film 40 from the adhesive layer 20, the peeling force F1 is preferably 7 gf/25 mm or less, more preferably 5 gf/25 mm or less, and even more preferably 3 gf/25 mm or less. Particularly preferably, it is 2.5 gf/25 mm or less. From the viewpoint of suppressing unintended peeling of the cover film 40 from the adhesive layer 20, the peel force F1 is preferably 0.1 gf/25 mm or more, more preferably 0.3 gf/25 mm or more, and still more preferably 0.5 gf/25 mm or more. 25 mm or more. Methods for adjusting the peel force F1 include, for example, selection of the type of base polymer for the adhesive layer 20, adjustment of the molecular weight, and adjustment of the blending amount. Selection of the type of base polymer includes selection of the type (structure) of the main chain in the base polymer, and selection of the type and adjustment of the amount of functional groups (the selection of the type of base polymer described later also includes similar). Methods for adjusting the peeling force F1 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 20 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
　そして、光学フィルムＸ２は、上述のように、光学フィルム１０の厚さＨ１が１００μｍ以下であり、粘着剤層２０の厚さＨ２が５μｍ以上１００μｍ以下であり、粘着剤層３０の厚さＨ３が５μｍ以上３０μｍ以下であり、粘着剤層２０のせん断貯蔵弾性率Ｍ１が２０ｋＰａ以上１００ｋＰａ以下であり、粘着剤層３０のせん断貯蔵弾性率Ｍ２が１５０ｋＰａ以上であり、カバーフィルム４０の厚さＨ４が４０μｍ以上８０μｍ以下であり、カバーフィルム６０の厚さＨ５が４０μｍ以上８０μｍ以下であり、比率（Ｈ４／Ｈ５）が１以上であり、カバーフィルム６０の剥離力Ｆ２に対するカバーフィルム４０の剥離力Ｆ１の比率（Ｆ１／Ｆ２）が０.９以下であり、且つ剥離力Ｆ１が１０ｇｆ/２５ｍｍ以下である。このような光学フィルムＸ２は、後記の実施例および比較例をもって示すように、光学フィルムＹ２（粘着剤層２０付きの薄い光学フィルム１０）から、粘着剤層３０付きカバーフィルム６０の剥離と光学フィルム１０端部のクラックとを抑制しつつ、カバーフィルム４０を剥離するのに適する。 In the optical film X2, as described above, the thickness H1 of the optical film 10 is 100 μm or less, the thickness H2 of the adhesive layer 20 is 5 μm or more and 100 μm or less, and the thickness H3 of the adhesive layer 30 is the adhesive layer 20 has a shear storage modulus M1 of 20 kPa or more and 100 kPa or less; the adhesive layer 30 has a shear storage modulus M2 of 150 kPa or more; and the thickness H4 of the cover film 40 is 40 μm. The thickness H5 of the cover film 60 is 40 μm or more and 80 μm or less, the ratio (H4/H5) is 1 or more, and the ratio of the peel force F1 of the cover film 40 to the peel force F2 of the cover film 60 (F1/F2) is 0.9 or less, and the peel force F1 is 10 gf/25 mm or less. Such an optical film X2 is obtained by peeling the cover film 60 with the pressure-sensitive adhesive layer 30 from the optical film Y2 (thin optical film 10 with the pressure-sensitive adhesive layer 20) and the optical film 10 Suitable for peeling off the cover film 40 while suppressing cracks at the ends.
　光学フィルムＸ２において、粘着剤層３０の厚さＨ３に対する粘着剤層２０の厚さＨ２の比率（Ｈ２／Ｈ３）は、折り曲げ性および段差吸収性の観点から、好ましくは１以上、より好ましくは２以上、更に好ましくは３以上、特に好ましくは５以上である。折り曲げ性および段差吸収性の観点から、比率（Ｈ２／Ｈ３）は、好ましくは１００以下、より好ましくは５０以下、更に好ましくは３０以下、特に好ましくは２０以下である。 In the optical film X2, the ratio (H2/H3) of the thickness H2 of the pressure-sensitive adhesive layer 20 to the thickness H3 of the pressure-sensitive adhesive layer 30 is preferably 1 or more, more preferably 2, from the viewpoint of bendability and step absorption. Above, more preferably 3 or more, particularly preferably 5 or more. From the viewpoint of bendability and step absorbability, the ratio (H2/H3) is preferably 100 or less, more preferably 50 or less, even more preferably 30 or less, and particularly preferably 20 or less.
　粘着剤層３０のせん断貯蔵弾性率Ｍ２に対する粘着剤層２０のせん断貯蔵弾性率Ｍ１の比率（Ｍ１／Ｍ２）は、折り曲げ性および段差吸収性の観点から、好ましくは０.５以下、より好ましくは０.２以下、更に好ましくは０.１以下、殊更に好ましくは０.０５以下、特に好ましくは０.０２以下である。折り曲げ性および段差吸収性の観点から、比率（Ｍ１／Ｍ２）は、好ましくは０.００５以上、より好ましくは０.０１以上、更に好ましくは０.０１５以上である。 The ratio (M1/M2) of the shear storage modulus M1 of the adhesive layer 20 to the shear storage modulus M2 of the adhesive layer 30 is preferably 0.5 or less, more preferably It is 0.2 or less, more preferably 0.1 or less, particularly preferably 0.05 or less, particularly preferably 0.02 or less. The ratio (M1/M2) is preferably 0.005 or more, more preferably 0.01 or more, and still more preferably 0.015 or more, from the viewpoint of bendability and step absorbability.
　粘着剤層３０付きカバーフィルム６０の剥離力Ｆ２は、光学フィルム１０から粘着剤層３０付きカバーフィルム６０の意図しない剥離を抑制する観点から、好ましくは０.１１ｇｆ/２５ｍｍ以上、より好ましくは０.３３ｇｆ/２５ｍｍ以上、更に好ましくは０.５５ｇｆ/２５ｍｍ以上である。粘着剤層３０からのカバーフィルム６０の剥離時に良好な剥離作業を確保する観点から、剥離力Ｆ２は、好ましくは２０ｇｆ/２５ｍｍ以下、より好ましくは１９ｇｆ/２５ｍｍ以下、更に好ましくは１８ｇｆ/２５ｍｍ以下である。剥離力Ｆ２の調整方法としては、例えば、粘着剤層３０のためのベースポリマーの種類の選択、分子量の調整、および配合量の調整が挙げられる。剥離力Ｆ２の調整方法としては、粘着剤層３０におけるベースポリマー以外の成分の種類の選択、および、当該成分の配合量の調整も挙げられる。当該成分としては、架橋剤、シランカップリング剤、およびオリゴマーが挙げられる。 From the viewpoint of suppressing unintended peeling of the cover film 60 with the adhesive layer 30 from the optical film 10, the peeling force F2 of the cover film 60 with the adhesive layer 30 is preferably 0.11 gf/25 mm or more, more preferably 0. It is 33 gf/25 mm or more, more preferably 0.55 gf/25 mm or more. From the viewpoint of ensuring a good peeling operation when peeling the cover film 60 from the adhesive layer 30, the peeling force F2 is preferably 20 gf/25 mm or less, more preferably 19 gf/25 mm or less, and even more preferably 18 gf/25 mm or less. be. Methods for adjusting the peel force F2 include, for example, selection of the type of base polymer for the pressure-sensitive adhesive layer 30, adjustment of the molecular weight, and adjustment of the blending amount. Methods for adjusting the peel force F2 include selection of types of components other than the base polymer in the pressure-sensitive adhesive layer 30 and adjustment of the compounding amounts of the components. Such components include crosslinkers, silane coupling agents, and oligomers.
　カバーフィルム６０（表面保護フィルム）としては、例えば、可撓性と透明性とを兼ね備えたプラスチックフィルムが挙げられる。当該プラスチックフィルムとしては、例えば、ポリエチレンテレフタレートフィルム、ポリエチレンフィルム、ポリプロピレンフィルム、およびポリエステルフィルムが挙げられる。 Examples of the cover film 60 (surface protection film) include a plastic film having both flexibility and transparency. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film.
　光学フィルムＸ２は、例えば、次のようにして製造できる。 The optical film X2 can be produced, for example, as follows.
　まず、光学フィルム１０と、カバーフィルム４０付きの粘着剤層２０と、粘着剤層３０付きカバーフィルム６０とを用意する（用意工程）。カバーフィルム４０付き粘着剤層２０の形成方法は、第１の実施形態に関して上述したとおりである。 First, the optical film 10, the adhesive layer 20 with the cover film 40, and the cover film 60 with the adhesive layer 30 are prepared (preparation step). The method for forming the pressure-sensitive adhesive layer 20 with the cover film 40 is as described above for the first embodiment.
　粘着剤層３０付きカバーフィルム６０の形成においては、まず、カバーフィルム６０の表面をプラズマ処理する。次に、カバーフィルム６０のプラズマ処理面上に所定の粘着剤組成物（ワニス）を塗布して塗膜を形成した後、当該塗膜を乾燥する。これにより、粘着剤層３０付きカバーフィルム６０が得られる。カバーフィルム６０上の粘着剤層３０の上に更に別の剥離フィルムを積層してもよい。この剥離フィルムは、光学フィルム１０と粘着剤層３０との貼り合わせの前に剥離される。 In forming the cover film 60 with the adhesive layer 30, first, the surface of the cover film 60 is plasma-treated. Next, a predetermined adhesive composition (varnish) is applied to the plasma-treated surface of the cover film 60 to form a coating film, and then the coating film is dried. Thereby, the cover film 60 with the adhesive layer 30 is obtained. Another release film may be laminated on the adhesive layer 30 on the cover film 60 . This peeling film is peeled off before bonding the optical film 10 and the adhesive layer 30 together.
　次に、光学フィルム１０の第１面１１と、カバーフィルム４０付き粘着剤層２０の粘着剤層２０側とを、貼り合わせる（第１貼合せ工程）。好ましくは、この貼り合わせの前に、光学フィルム１０の第１面１１と、カバーフィルム４０付き粘着剤層２０の露出面とは、プラズマ処理される。 Next, the first surface 11 of the optical film 10 and the pressure-sensitive adhesive layer 20 side of the pressure-sensitive adhesive layer 20 with the cover film 40 are pasted together (first pasting step). Preferably, the first surface 11 of the optical film 10 and the exposed surface of the pressure-sensitive adhesive layer 20 with the cover film 40 are plasma-treated prior to this lamination.
　次に、光学フィルム１０の第２面１２と、粘着剤層３０付きカバーフィルム６０の粘着剤層３０側とを、貼り合わせる（第２貼合せ工程）。 Next, the second surface 12 of the optical film 10 and the pressure-sensitive adhesive layer 30 side of the cover film 60 with the pressure-sensitive adhesive layer 30 are pasted together (second pasting step).
　以上のようにして、上述の光学フィルムＸ２（カバーフィルム付き光学フィルム）を製造できる。光学フィルムＸ２は、打ち抜き加工によって成形してもよい。打ち抜き加工においては、例えば、打抜き加工機およびトムソン刃を使用する。 As described above, the optical film X2 (optical film with cover film) can be produced. The optical film X2 may be formed by punching. In punching, for example, a punching machine and a Thomson blade are used.
　図４Ａおよび図４Ｂは、光学フィルムＸ２の使用方法の一例を表す。 4A and 4B show an example of how to use the optical film X2.
　本方法では、まず、図４Ａに示すように、光学フィルムＸ２の粘着剤層２０からカバーフィルム４０を剥離する。例えば、光学フィルムＸ２のカバーフィルム６０側をワークテーブル上に固定した状態で、カバーフィルム４０の端部に力を作用させて、粘着剤層２０からカバーフィルム４０を剥離する。これにより、粘着剤層２０の粘着面２１が露出する。本工程において、光学フィルムＸ２は、上述のように、粘着剤層２０付きの薄い光学フィルム１０から、粘着剤層３０付きカバーフィルム６０の剥離と光学フィルム１０端部のクラックとを抑制しつつ、カバーフィルム４０を剥離するのに適する。 In this method, first, as shown in FIG. 4A, the cover film 40 is peeled off from the adhesive layer 20 of the optical film X2. For example, while the cover film 60 side of the optical film X2 is fixed on a work table, force is applied to the edge of the cover film 40 to separate the cover film 40 from the adhesive layer 20 . Thereby, the adhesive surface 21 of the adhesive layer 20 is exposed. In this step, as described above, the optical film X2 suppresses peeling of the cover film 60 with the adhesive layer 30 from the thin optical film 10 with the adhesive layer 20 and cracks at the edges of the optical film 10. Suitable for peeling off the cover film 40 .
　次に、図４Ｂに示すように、粘着剤層２０を介して光学フィルム１０と第１部材Ｍ１（第１被着体）とを接合する。第１部材Ｍ１は、例えば、フレキシブルパネルが有する積層構造中の一要素である。当該要素としては、例えば、画素パネル、およびタッチパネルが挙げられる。 Next, as shown in FIG. 4B, the optical film 10 and the first member M1 (first adherend) are bonded with the adhesive layer 20 interposed therebetween. The first member M1 is, for example, one element in the laminated structure of the flexible panel. Such elements include, for example, pixel panels and touch panels.
　例えばフレキシブルパネルの製造過程において、光学フィルムＸ２は以上のように使用される。 For example, in the manufacturing process of flexible panels, the optical film X2 is used as described above.
　本発明について、以下に実施例を示して具体的に説明する。本発明は、実施例に限定されない。また、以下に記載されている配合量（含有量）、物性値、パラメータなどの具体的数値は、上述の「発明を実施するための形態」において記載されている、それらに対応する配合量（含有量）、物性値、パラメータなどの上限（「以下」または「未満」として定義されている数値）または下限（「以上」または「超える」として定義されている数値）に代替できる。 The present invention will be specifically described below with reference to examples. The invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), physical property values, parameters, etc. described below are the corresponding compounding amounts ( content), physical properties, parameters, etc., upper limits (values defined as “less than” or “less than”) or lower limits (values defined as “greater than” or “greater than”).
〈第１アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸２－エチルヘキシル（２ＥＨＡ）６３質量部と、アクリル酸ｎ－ブチル（ＢＡ）２７質量部と、アクリル酸４－ヒドロキシブチル（４ＨＢＡ）７.５質量部と、アクリル酸（ＡＡ）１質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチルとを含む混合物を、５６℃で６時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第１アクリルベースポリマーを含有する第１ポリマー溶液を得た。このポリマー溶液中の第１アクリルベースポリマーの重量平均分子量は約２００万であった。 <Preparation of first acrylic base polymer>
63 parts by mass of 2-ethylhexyl acrylate (2EHA), 27 parts by mass of n-butyl acrylate (BA), acrylic acid 7.5 parts by mass of 4-hydroxybutyl (4HBA), 1 part by mass of acrylic acid (AA), and 0.3 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator , and ethyl acetate as solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a first polymer solution containing the first acrylic base polymer. The weight average molecular weight of the first acrylic base polymer in this polymer solution was about 2 million.
〈第２アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸２－エチルヘキシル（２ＥＨＡ）７０質量部と、アクリル酸ｎ－ブチル（ＢＡ）２０質量部と、ラウリルアクリレート（ＬＡ）８質量部と、アクリル酸４－ヒドロキシブチル（４ＨＢＡ）１質量部と、Ｎ－ビニル－２－ピロリドン（ＮＶＰ）０.６質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチルとを含む混合物を、５６℃で６時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第２アクリルベースポリマーを含有する第２ポリマー溶液を得た。このポリマー溶液中の第２アクリルベースポリマーの重量平均分子量は約２００万であった。 <Preparation of second acrylic base polymer>
70 parts by mass of 2-ethylhexyl acrylate (2EHA), 20 parts by mass of n-butyl acrylate (BA), and lauryl acrylate were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. (LA) 8 parts by mass, 4-hydroxybutyl acrylate (4HBA) 1 part by mass, N-vinyl-2-pyrrolidone (NVP) 0.6 parts by mass, and 2,2′- as a thermal polymerization initiator A mixture containing 0.3 parts by mass of azobisisobutyronitrile (AIBN) and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a second polymer solution containing a second acrylic base polymer. The weight average molecular weight of the second acrylic base polymer in this polymer solution was about 2 million.
〈第３アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸２－エチルヘキシル（２ＥＨＡ）６０質量部と、ラウリルアクリレート（ＬＡ）３６.５質量部と、アクリル酸４－ヒドロキシブチル（４ＨＢＡ）８質量部と、Ｎ－ビニル－２－ピロリドン（ＮＶＰ）２.５質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチルとを含む混合物を、５６℃で６時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第３アクリルベースポリマーを含有する第３ポリマー溶液を得た。このポリマー溶液中の第３アクリルベースポリマーの重量平均分子量は約２００万であった。 <Preparation of the third acrylic base polymer>
60 parts by mass of 2-ethylhexyl acrylate (2EHA), 36.5 parts by mass of lauryl acrylate (LA), and 4 parts by mass of acrylic acid were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. - 8 parts by weight of hydroxybutyl (4HBA), 2.5 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 0.5 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator. A mixture containing 3 parts by mass and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a third polymer solution containing a third acrylic base polymer. The weight average molecular weight of the third acrylic base polymer in this polymer solution was about 2 million.
〈第４アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸ブチル（ＢＡ）９９質量部と、アクリル酸４－ヒドロキシブチル（４ＨＢＡ）１質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチルとを含む混合物を、６０℃で４時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第４アクリルベースポリマーを含有する第４ポリマー溶液を得た。このポリマー溶液中の第４アクリルベースポリマーの重量平均分子量は約１７０万であった。 <Preparation of the fourth acrylic base polymer>
99 parts by mass of butyl acrylate (BA), 1 part by mass of 4-hydroxybutyl acrylate (4HBA), and thermal polymerization start in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube. A mixture containing 0.3 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as an agent and ethyl acetate as a solvent was stirred at 60° C. for 4 hours under a nitrogen atmosphere (polymerization reaction ). This gave a fourth polymer solution containing the fourth acrylic base polymer. The weight average molecular weight of the fourth acrylic base polymer in this polymer solution was about 1.7 million.
〈第５アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸２－エチルヘキシル（２ＥＨＡ）６６質量部と、アクリル酸２－ヒドロキシエチル（ＨＥＡ）１８質量部と、Ｎ－ビニル－２－ピロリドン（ＮＶＰ）１５質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチルとを含む混合物を、５６℃で６時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第５アクリルベースポリマーを含有する第５ポリマー溶液を得た。このポリマー溶液中の第５アクリルベースポリマーの重量平均分子量は約２００万であった。 <Preparation of the fifth acrylic base polymer>
66 parts by mass of 2-ethylhexyl acrylate (2EHA), 18 parts by mass of 2-hydroxyethyl acrylate (HEA), N - A mixture containing 15 parts by mass of vinyl-2-pyrrolidone (NVP), 0.3 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as a solvent was stirred at 56° C. for 6 hours under a nitrogen atmosphere (polymerization reaction). This gave a fifth polymer solution containing the fifth acrylic base polymer. The weight average molecular weight of the fifth acrylic base polymer in this polymer solution was about 2 million.
〈第６アクリルベースポリマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、アクリル酸２－エチルヘキシル（２ＥＨＡ）９６.２質量部と、アクリル酸２－ヒドロキシエチル（ＨＥＡ）３.８質量部と、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）０.３質量部と、溶媒としての酢酸エチル１５０質量部とを含む混合物を、６５℃で６時間、窒素雰囲気下で撹拌した（重合反応）。これにより、第６アクリルベースポリマーを含有する第６ポリマー溶液を得た。このポリマー溶液中の第６アクリルベースポリマーの重量平均分子量は５４万であった。 <Preparation of the sixth acrylic base polymer>
96.2 parts by mass of 2-ethylhexyl acrylate (2EHA) and 3.8 parts by mass of 2-hydroxyethyl acrylate (HEA) were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. parts, 0.3 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and 150 parts by mass of ethyl acetate as a solvent, at 65 ° C. for 6 hours, Stirred under a nitrogen atmosphere (polymerization reaction). This gave a sixth polymer solution containing a sixth acrylic base polymer. The weight average molecular weight of the sixth acrylic base polymer in this polymer solution was 540,000.
〈アクリルオリゴマーの調製〉
　撹拌機、温度計、還流冷却器、および窒素ガス導入管を備える反応容器内で、メタクリル酸シクロヘキシル（ＣＨＭＡ）９５質量部と、アクリル酸（ＡＡ）５質量部と、連鎖移動剤としてのα－メチルスチレンダイマー １０質量部と、溶媒としてのトルエン１２０質量部とを含む混合物を、室温で１時間、窒素雰囲気下にて撹拌した。その後、混合物に、熱重合開始剤としての２,２'－アゾビスイソブチロニトリル（ＡＩＢＮ）１０質量部を加えて反応溶液を調製し、窒素雰囲気下において、８５℃で５時間、反応させた（アクリルオリゴマーの形成）。これにより、アクリルオリゴマーを含有するオリゴマー溶液（固形分濃度５０質量％）得た。アクリルオリゴマーの重量平均分子量は４０００であった。
また、アクリルオリゴマーのガラス転移温度（Ｔｇ）は８４℃であった。 <Preparation of acrylic oligomer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 95 parts by mass of cyclohexyl methacrylate (CHMA), 5 parts by mass of acrylic acid (AA), and α- A mixture containing 10 parts by mass of methylstyrene dimer and 120 parts by mass of toluene as a solvent was stirred at room temperature for 1 hour under a nitrogen atmosphere. After that, 10 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator is added to the mixture to prepare a reaction solution, which is reacted at 85° C. for 5 hours under a nitrogen atmosphere. (formation of acrylic oligomers). As a result, an oligomer solution containing an acrylic oligomer (solid concentration: 50% by mass) was obtained. The acrylic oligomer had a weight average molecular weight of 4,000.
Moreover, the glass transition temperature (Tg) of the acrylic oligomer was 84°C.
〔実施例１〕
＜第１粘着シートの作製＞
　以下のようにして、実施例１における第１粘着シートを作製した。 [Example 1]
<Production of first adhesive sheet>
A first pressure-sensitive adhesive sheet in Example 1 was produced as follows.
〈第１粘着剤組成物の調製〉
　第１ポリマー溶液に、当該ポリマー溶液中の第１アクリルベースポリマー１００質量部あたり、アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，ジベンゾイルパーオキシド，日本油脂製）０.３質量部と、第２架橋剤（品名「コロネートＬ」，トリメチロールプロパン／トリレンジイソシアネート３量体付加物，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合し、第１粘着剤組成物を調製した。 <Preparation of first adhesive composition>
In the first polymer solution, 1.5 parts by mass of an acrylic oligomer per 100 parts by mass of the first acrylic base polymer in the polymer solution, and a first cross-linking agent (product name "Niper BMT-40SV", dibenzoyl peroxide, NOF ), 0.3 parts by mass of the second cross-linking agent (product name "Coronate L", trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Tosoh) 0.02 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) (0.3 parts by mass) was added and mixed to prepare a first adhesive composition.
〈第１粘着シートの形成〉
　片面がシリコーン剥離処理された剥離フィルムＬ１の剥離処理面上に、第１粘着剤組成物を塗布して塗膜を形成した。剥離フィルムＬ１は、片面がシリコーン剥離処理されたポリエチレンテレフタレート（ＰＥＴ）フィルム（品名「ダイアホイル ＭＨＥ５０」，厚さ５０μｍ，三菱ケミカル社製）である。次に、剥離フィルムＬ１上の塗膜に、片面がシリコーン剥離処理された剥離フィルムＬ２の剥離処理面を貼り合わせた。剥離フィルムＬ２は、片面がシリコーン剥離処理されたＰＥＴフィルム（品名「ダイアホイル ＭＲＶ７５」，厚さ７５μｍ，三菱ケミカル社製）である。次に、剥離フィルムＬ１と剥離フィルムＬ２とに挟まれた塗膜を、１００℃で１分間の加熱とその後の１５０℃で３分間の加熱とによって乾燥し、厚さ５０μｍの透明な第１粘着剤層よりなる第１粘着シートを形成した。以上のようにして、剥離フィルムＬ１,Ｌ２付きの第１粘着シートを作製した。 <Formation of first adhesive sheet>
A coating film was formed by applying the first pressure-sensitive adhesive composition onto the release-treated surface of release film L1, one surface of which had been subjected to silicone release treatment. The release film L1 is a polyethylene terephthalate (PET) film (product name “DIAFOIL MHE50”, thickness 50 μm, manufactured by Mitsubishi Chemical Co., Ltd.) with one side subjected to silicone release treatment. Next, the release-treated surface of the release film L2, one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L1. The release film L2 is a PET film (product name “DIAFOIL MRV75”, thickness 75 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the coating film sandwiched between the release film L1 and the release film L2 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to form a transparent first adhesive having a thickness of 50 μm. A first pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the first pressure-sensitive adhesive sheets with release films L1 and L2 were produced.
＜第２粘着シートの作製＞
　以下のようにして、実施例１における第２粘着シートを作製した。 <Production of second adhesive sheet>
A second pressure-sensitive adhesive sheet in Example 1 was produced as follows.
〈第２粘着剤組成物の調製〉
　第２ポリマー溶液に、当該ポリマー溶液の固形分１００質量部あたり、アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.２６質量部と、第２架橋剤（品名「コロネートＬ」，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合し、第２粘着剤組成物を調製した。 <Preparation of second adhesive composition>
In the second polymer solution, 1.5 parts by mass of an acrylic oligomer per 100 parts by mass of the solid content of the polymer solution, 0.26 parts by mass of a first cross-linking agent (product name "Nyper BMT-40SV", manufactured by NOF), 0.02 parts by mass of a second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) and 0.3 parts by mass of a silane coupling agent (product name “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) are added and mixed, and the second An adhesive composition was prepared.
〈第２粘着シートの形成〉
　片面がシリコーン剥離処理された剥離フィルムＬ３の剥離処理面上に、第２粘着剤組成物を塗布して塗膜を形成した。剥離フィルムＬ３は、片面がシリコーン剥離処理されたポリエチレンテレフタレート（ＰＥＴ）フィルム（品名「ダイアホイル ＭＨＥ５０」，厚さ５０μｍ，三菱ケミカル社製）である。次に、剥離フィルムＬ３上の塗膜に、片面がシリコーン剥離処理された剥離フィルムＬ４の剥離処理面を貼り合わせた。剥離フィルムＬ４は、片面がシリコーン剥離処理されたＰＥＴフィルム（品名「ダイアホイル ＭＲＶ７５」，厚さ７５μｍ，三菱ケミカル社製）である。次に、剥離フィルムＬ３と剥離フィルムＬ４とに挟まれた塗膜を、１００℃で１分間の加熱とその後の１５０℃で３分間の加熱とによって乾燥し、厚さ５０μｍの透明な第２粘着剤層よりなる第２粘着シートを形成した。以上のようにして、剥離フィルムＬ３,Ｌ４付きの第２粘着シートを作製した。 <Formation of second adhesive sheet>
A coating film was formed by applying the second pressure-sensitive adhesive composition onto the release-treated surface of release film L3, one surface of which had been subjected to silicone release treatment. The release film L3 is a polyethylene terephthalate (PET) film (product name “DIAFOIL MHE50”, thickness 50 μm, manufactured by Mitsubishi Chemical Co., Ltd.) having one side subjected to silicone release treatment. Next, the release-treated surface of the release film L4, one side of which was subjected to silicone release treatment, was attached to the coating film on the release film L3. The release film L4 is a PET film (product name “DIAFOIL MRV75”, thickness 75 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment. Next, the coating film sandwiched between the release film L3 and the release film L4 is dried by heating at 100° C. for 1 minute and then heating at 150° C. for 3 minutes to obtain a transparent second adhesive having a thickness of 50 μm. A second pressure-sensitive adhesive sheet consisting of an agent layer was formed. As described above, the second adhesive sheets with release films L3 and L4 were produced.
＜カバーフィルム付き光学フィルムの作製＞
　まず、両面剥離フィルム付き第１粘着シートから剥離フィルムＬ２を剥離し、これによって露出した露出面をプラズマ処理した。一方、厚さ３１μｍの偏光フィルムの両面（第１面，第２面）も、プラズマ処理した。各プラズマ処理では、プラズマ照射装置（品名「ＡＰ－ＴＯ５」，積水工業社製）を使用し、電圧を１６０Ｖとし、周波数を１０ｋＨｚとし、処理速度を５０００ｍｍ/分とした（後記のプラズマ処理においても同様である）。そして、第１粘着シートの上記露出面と、偏光フィルムの第１面とを、貼り合わせた。この貼り合わせでは、２５℃の環境下において、２ｋｇのローラーを１往復させる作業により、剥離フィルムＬ１付き第１粘着シートと偏光フィルムとを圧着させた。 <Production of optical film with cover film>
First, the release film L2 was peeled off from the first pressure-sensitive adhesive sheet with a double-sided release film, and the exposed surface thereby exposed was plasma-treated. On the other hand, both surfaces (first surface and second surface) of the polarizing film having a thickness of 31 μm were also plasma-treated. In each plasma treatment, a plasma irradiation device (product name “AP-TO5”, manufactured by Sekisui Kogyo Co., Ltd.) was used, the voltage was 160 V, the frequency was 10 kHz, and the treatment speed was 5000 mm / min (also in the plasma treatment described later similar). Then, the exposed surface of the first adhesive sheet and the first surface of the polarizing film were bonded together. In this bonding, the first pressure-sensitive adhesive sheet with the release film L1 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C.
　次に、剥離フィルムＬ３,Ｌ４付き第２粘着シートから剥離フィルムＬ３を剥離し、これによって露出した露出面をプラズマ処理した。そして、第２粘着シートの露出面と、偏光フィルムの第２面とを、貼り合わせた。この貼り合わせでは、２５℃の環境下において、２ｋｇのローラーを１往復させる作業により、剥離フィルムＬ４付き第２粘着シートと偏光フィルムとを圧着させた。これにより、剥離フィルムＬ１（厚さ５０μｍ）と、第１粘着シート（厚さ５０μｍ）と、偏光フィルム（厚さ３１μｍ）と、第２粘着シート（厚さ５０μｍ）と、剥離フィルムＬ４（厚さ７５μｍ）との積層構成の積層フィルムを得た。 Next, the release film L3 was peeled off from the second adhesive sheet with the release films L3 and L4, and the exposed surface was plasma-treated. Then, the exposed surface of the second adhesive sheet and the second surface of the polarizing film were bonded together. In this bonding, the second pressure-sensitive adhesive sheet with the release film L4 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C. As a result, the release film L1 (thickness 50 μm), the first adhesive sheet (thickness 50 μm), the polarizing film (thickness 31 μm), the second adhesive sheet (thickness 50 μm), the release film L4 (thickness 75 μm) was obtained.
　次に、打抜き加工機およびトムソン刃を使用して、積層フィルムを１５０ｍｍ×１２０ｍｍのサイズに打ち抜いた（打抜き加工）。 Next, using a punching machine and a Thomson blade, the laminated film was punched into a size of 150 mm x 120 mm (punching).
　以上のようにして、実施例１のカバーフィルム付き光学フィルムを作製した。このカバーフィルム付き光学フィルムは、第１カバーフィルムとしての剥離フィルムＬ１と、第１粘着剤層（第１粘着シート）と、光学フィルムとしての偏光フィルムと、第２粘着剤層（第２粘着シート）と、第２カバーフィルムとしての剥離フィルムＬ４とを厚さ方向に順に備える。 An optical film with a cover film of Example 1 was produced as described above. This optical film with a cover film includes a release film L1 as a first cover film, a first adhesive layer (first adhesive sheet), a polarizing film as an optical film, and a second adhesive layer (second adhesive sheet ) and a release film L4 as a second cover film are provided in order in the thickness direction.
〔実施例２～５〕
　以下のこと以外は、実施例１のカバーフィルム付き光学フィルムと同様にして、実施例２～５の各カバーフィルム付き光学フィルムを作製した。 [Examples 2 to 5]
Optical films with cover films of Examples 2 to 5 were produced in the same manner as the optical film with cover film of Example 1 except for the following.
　実施例２では、厚さ３１μｍの偏光フィルムに代えて厚さ５１μｍの偏光フィルムを用いた。 In Example 2, a polarizing film with a thickness of 51 μm was used in place of the polarizing film with a thickness of 31 μm.
　実施例３では、厚さ３１μｍの偏光フィルムに代えて厚さ２５μｍの偏光フィルムを用いた。 In Example 3, a polarizing film with a thickness of 25 μm was used in place of the polarizing film with a thickness of 31 μm.
　実施例４では、第１粘着シートの厚さを５０μｍに代えて２５μｍとした。 In Example 4, the thickness of the first adhesive sheet was changed from 50 µm to 25 µm.
　実施例５では、第１粘着シートの厚さを５０μｍに代えて２５μｍとし、且つ、第２粘着シートの厚さを５０μｍに代えて７５μｍとした。 In Example 5, the thickness of the first adhesive sheet was changed from 50 µm to 25 µm, and the thickness of the second adhesive sheet was changed from 50 µm to 75 µm.
〔実施例６〕
　以下のこと以外は、実施例１のカバーフィルム付き光学フィルムと同様にして、実施例６のカバーフィルム付き光学フィルムを作製した。第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第２ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。第２粘着剤組成物の調製において、第２ポリマー溶液に代えて第３ポリマー溶液を用い、当該第２粘着剤組成物を用いて厚さ７５μｍの第２粘着シートを作製した。 [Example 6]
An optical film with a cover film of Example 6 was produced in the same manner as the optical film with a cover film of Example 1 except for the following. In the preparation of the first pressure-sensitive adhesive composition, a second polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition. In the preparation of the second pressure-sensitive adhesive composition, a third polymer solution was used instead of the second polymer solution, and a second pressure-sensitive adhesive sheet having a thickness of 75 μm was produced using the second pressure-sensitive adhesive composition.
　実施例６における第１粘着剤組成物の調製では、具体的には、第２ポリマー溶液に、当該ポリマー溶液中の第２アクリルベースポリマー１００質量部あたり、アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.２６質量部と、第２架橋剤（品名「コロネートＬ」，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 Specifically, in the preparation of the first pressure-sensitive adhesive composition in Example 6, the second polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the second acrylic base polymer in the polymer solution, 1 cross-linking agent (product name “Nyper BMT-40SV”, manufactured by NOF) 0.26 parts by mass, second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
　実施例６における第２粘着剤組成物の調製では、具体的には、第３ポリマー溶液に、当該ポリマー溶液中の第３アクリルベースポリマー１００質量部あたり、アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.０８質量部と、第２架橋剤（品名「コロネートＬ」，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 Specifically, in the preparation of the second pressure-sensitive adhesive composition in Example 6, the third polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the third acrylic base polymer in the polymer solution, 1 cross-linking agent (product name "Nyper BMT-40SV", manufactured by NOF) 0.08 parts by mass, second cross-linking agent (product name "Coronate L", manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
〔実施例７〕
　以下のこと以外は、実施例１のカバーフィルム付き光学フィルムと同様にして、実施例７のカバーフィルム付き光学フィルムを作製した。第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第４ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。第２粘着シートの厚さを５０μｍに代えて７５μｍとした。 [Example 7]
An optical film with a cover film of Example 7 was produced in the same manner as the optical film with a cover film of Example 1 except for the following. In the preparation of the first pressure-sensitive adhesive composition, a fourth polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition. The thickness of the second adhesive sheet was changed from 50 μm to 75 μm.
　実施例７における第１粘着剤組成物の調製では、具体的には、第４ポリマー溶液に、当該ポリマー溶液中の第４アクリルベースポリマー１００質量部あたり、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.３質量部と、第３架橋剤（品名「タケネートＤ１１０Ｎ」，トリメチロールプロパンキシリレンジイソシアネート，三井化学製）０.１質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 Specifically, in the preparation of the first pressure-sensitive adhesive composition in Example 7, the fourth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass were added and mixed.
〔比較例１～５〕
　以下のこと以外は、実施例１のカバーフィルム付き光学フィルムと同様にして、比較例１～５の各カバーフィルム付き光学フィルムを作製した。 [Comparative Examples 1 to 5]
Optical films with cover films of Comparative Examples 1 to 5 were produced in the same manner as the optical film with cover film of Example 1 except for the following.
　比較例１では、剥離フィルムＬ４（厚さ７５μｍ）の代わりに剥離フィルムＬ５を用いた。剥離フィルムＬ５は、片面がシリコーン剥離処理されたＰＥＴフィルム（厚さ１２５μｍ）である。 In Comparative Example 1, a release film L5 was used instead of the release film L4 (thickness 75 μm). The release film L5 is a PET film (thickness: 125 μm) with one side subjected to silicone release treatment.
　比較例２では、剥離フィルムＬ１（厚さ５０μｍ）の代わりに剥離フィルムＬ６を用い、且つ、剥離フィルムＬ４（厚さ７５μｍ）の代わりに剥離フィルムＬ６を用いた。剥離フィルムＬ６は、片面がシリコーン剥離処理されたＰＥＴフィルム（品名「ダイアホイルＭＲＦ３８」，厚さ３８μｍ，三菱ケミカル社製）である。 In Comparative Example 2, a release film L6 was used instead of the release film L1 (thickness 50 μm), and a release film L6 was used instead of the release film L4 (thickness 75 μm). The release film L6 is a PET film (product name “Diafoil MRF38”, thickness 38 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
　比較例３では、第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第５ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。比較例３における第１粘着剤組成物の調製では、具体的には、第５ポリマー溶液に、当該ポリマー溶液中の第５アクリルベースポリマー１００質量部あたり、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.３質量部と、第３架橋剤（品名「タケネートＤ１１０Ｎ」，三井化学製）０.１質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 In Comparative Example 3, a fifth polymer solution was used in place of the first polymer solution in the preparation of the first pressure-sensitive adhesive composition, and the first pressure-sensitive adhesive composition was used to prepare the first pressure-sensitive adhesive sheet. Specifically, in the preparation of the first pressure-sensitive adhesive composition in Comparative Example 3, the fifth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd. ) and 0.3 parts by mass were added and mixed.
　比較例４では、剥離フィルムＬ１（厚さ５０μｍ）の代わりに上記の剥離フィルムＬ２を用い、剥離フィルムＬ４（厚さ５０μｍ）の代わりに剥離フィルムＬ７を用い、且つ、第２粘着シートの厚さを５０μｍに代えて７５μｍとした。剥離フィルムＬ７は、片面がシリコーン剥離処理されたＰＥＴフィルム（品名「ダイアホイル ＭＲＦ５０」，厚さ５０μｍ，三菱ケミカル社製）である。 In Comparative Example 4, the release film L2 was used instead of the release film L1 (thickness 50 μm), the release film L7 was used instead of the release film L4 (thickness 50 μm), and the thickness of the second adhesive sheet was was changed from 50 μm to 75 μm. The release film L7 is a PET film (product name “Diafoil MRF50”, thickness 50 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
　比較例５では、剥離フィルムＬ１（厚さ５０μｍ）の代わりに上記の剥離フィルムＬ２を用い、剥離フィルムＬ４（厚さ５０μｍ）の代わりに上記の剥離フィルムＬ２を用い、且つ、第２粘着シートの厚さを５０μｍに代えて７５μｍとした。 In Comparative Example 5, the release film L2 was used instead of the release film L1 (thickness of 50 μm), the release film L2 was used instead of the release film L4 (thickness of 50 μm), and the second adhesive sheet was The thickness was changed from 50 μm to 75 μm.
〔実施例８〕
＜第１粘着シートの作製＞
　実施例１における上述の第１粘着シートと同様にして、実施例８における第１粘着シートを作製した。実施例８における第１粘着シートは、実施例１においける第１粘着シートと同じであり、具体的には、剥離フィルムＬ１,Ｌ２付きの第１粘着シートである。この第１粘着シートは、厚さ５０μｍの透明な第１粘着剤層よりなる。この第１粘着剤層は、第１アクリルベースポリマー１００質量部と、上記アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.３質量部と、第２架橋剤（品名「コロネートＬ」，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを含む第１粘着剤組成物から形成された粘着剤層である。 [Example 8]
<Production of first adhesive sheet>
A first pressure-sensitive adhesive sheet in Example 8 was produced in the same manner as the above-described first pressure-sensitive adhesive sheet in Example 1. The first pressure-sensitive adhesive sheet in Example 8 is the same as the first pressure-sensitive adhesive sheet in Example 1, specifically the first pressure-sensitive adhesive sheet with release films L1 and L2. This first pressure-sensitive adhesive sheet consists of a transparent first pressure-sensitive adhesive layer with a thickness of 50 μm. This first pressure-sensitive adhesive layer is composed of 100 parts by mass of the first acrylic base polymer, 1.5 parts by mass of the above acrylic oligomer, and 0.3 parts by mass of the first cross-linking agent (product name "Niper BMT-40SV", manufactured by NOF). A first adhesive containing 0.02 parts by mass of a second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) and 0.3 parts by mass of a silane coupling agent (product name “KBM403”, manufactured by Shin-Etsu Chemical Co., Ltd.) It is an adhesive layer formed from the composition.
＜粘着剤層付きカバーフィルムの作製＞
　以下のようにして、実施例８における粘着剤層付きカバーフィルムを作製した。 <Preparation of cover film with adhesive layer>
A cover film with an adhesive layer in Example 8 was produced as follows.
　まず、第６ポリマー溶液に、当該ポリマー溶液中の第６アクリルベースポリマー１００質量部あたり、第４架橋剤（品名「コロネートＨＸ」，ヘキサメチレンジイソシアネートのイソシアヌレート体，東ソー製）５質量部と、架橋触媒としてのジラウリン酸ジブチルスズ０.０３質量部とを加えて混合し、実施例８における第２粘着剤組成物を調製した。 First, in the sixth polymer solution, 5 parts by mass of a fourth cross-linking agent (product name “Coronate HX”, isocyanurate of hexamethylene diisocyanate, manufactured by Tosoh) per 100 parts by mass of the sixth acrylic base polymer in the polymer solution, 0.03 parts by mass of dibutyltin dilaurate as a cross-linking catalyst was added and mixed to prepare a second pressure-sensitive adhesive composition in Example 8.
　次に、片面がコロナ処理された表面保護フィルム（品名「Ｔ１００Ｃ－３８」，ポリエステルフィルム，厚さ３８μｍ，三菱ケミカル社製）のコロナ処理面上に、実施例８における上述の第２粘着剤組成物を塗布して塗膜を形成した。次に、表面保護フィルム上の塗膜に、剥離フィルムＬ８の剥離処理面を貼り合わせた。剥離フィルムＬ８は、片面がシリコーン剥離処理されたポリエステルフィルム（厚さ２５μｍ）である。次に、両フィルムに挟まれた塗膜を、１３０℃で２分間の加熱によって乾燥し、厚さ１０μｍの透明な第２粘着剤層を形成した。この後、第２粘着剤層から剥離フィルムＬ８を剥離した。以上のようにして、粘着剤層付き表面保護フィルム（粘着剤層付きカバーフィルム）を作製した。 Next, on the corona-treated surface of a surface protective film (product name “T100C-38”, polyester film, thickness 38 μm, manufactured by Mitsubishi Chemical Corporation) one side of which was corona-treated, the second pressure-sensitive adhesive composition described above in Example 8 was applied. A material was applied to form a coating film. Next, the release-treated surface of the release film L8 was attached to the coating film on the surface protection film. The release film L8 is a polyester film (thickness: 25 μm) with one side subjected to silicone release treatment. Next, the coating film sandwiched between both films was dried by heating at 130° C. for 2 minutes to form a transparent second pressure-sensitive adhesive layer with a thickness of 10 μm. After that, the release film L8 was peeled off from the second pressure-sensitive adhesive layer. As described above, a surface protective film with an adhesive layer (cover film with an adhesive layer) was produced.
＜カバーフィルム付き光学フィルムの作製＞
　まず、両面剥離フィルムＬ１,Ｌ２付き第１粘着シートから剥離フィルムＬ２を剥離し、これによって露出した露出面をプラズマ処理した。一方、厚さ３１μｍの偏光フィルムの両面（第１面，第２面）も、プラズマ処理した。そして、第１粘着シートの上記露出面と、偏光フィルムの第１面とを、貼り合わせた。この貼り合わせでは、２５℃の環境下において、２ｋｇのローラーを１往復させる作業により、剥離フィルムＬ１付き第１粘着シートと偏光フィルムとを圧着させた。 <Production of optical film with cover film>
First, the release film L2 was peeled off from the first pressure-sensitive adhesive sheet with the double-sided release films L1 and L2, and the exposed surface was plasma-treated. On the other hand, both surfaces (first surface and second surface) of the polarizing film having a thickness of 31 μm were also plasma-treated. Then, the exposed surface of the first adhesive sheet and the first surface of the polarizing film were bonded together. In this bonding, the first pressure-sensitive adhesive sheet with the release film L1 and the polarizing film were pressure-bonded by reciprocating a 2-kg roller one time in an environment of 25°C.
　次に、上述の粘着剤層付き表面保護フィルムの粘着剤層側と、偏光フィルムの第２面とを、貼り合わせた。この貼り合わせでは、２５℃の環境下において、２ｋｇのローラーを１往復させる作業により、粘着剤層付き表面保護フィルムと偏光フィルムとを圧着させた。これにより、剥離フィルムＬ１（厚さ５０μｍ）と、第１粘着シート（厚さ５０μｍ）と、偏光フィルム（厚さ３１μｍ）と、粘着剤層（厚さ１０μｍ）付き表面保護フィルム（厚さ３８μｍ）との積層構成の積層フィルムを得た。 Next, the pressure-sensitive adhesive layer side of the surface protective film with the pressure-sensitive adhesive layer and the second surface of the polarizing film were adhered together. In this bonding, the pressure-sensitive adhesive layer-attached surface protective film and the polarizing film were pressure-bonded by reciprocating a 2-kg roller once in an environment of 25°C. As a result, the release film L1 (thickness 50 μm), the first adhesive sheet (thickness 50 μm), the polarizing film (thickness 31 μm), and the surface protective film (thickness 38 μm) with the adhesive layer (thickness 10 μm) A laminated film having a laminated structure of
　次に、打抜き加工機およびトムソン刃を使用して、積層フィルムを１５０ｍｍ×１２０ｍｍのサイズに打ち抜いた（打抜き加工）。 Next, using a punching machine and a Thomson blade, the laminated film was punched into a size of 150 mm x 120 mm (punching).
　以上のようにして、実施例８のカバーフィルム付き光学フィルムを作製した。このカバーフィルム付き光学フィルムは、第１カバーフィルムとしての剥離フィルムＬ１と、第１粘着剤層（第１粘着シート）と、光学フィルムとしての偏光フィルムと、第２粘着剤層付き第２カバーフィルムとしての粘着剤層付き表面保護フィルムとを、厚さ方向に順に備える。 An optical film with a cover film of Example 8 was produced as described above. This optical film with a cover film includes a release film L1 as a first cover film, a first pressure-sensitive adhesive layer (first pressure-sensitive adhesive sheet), a polarizing film as an optical film, and a second cover film with a second pressure-sensitive adhesive layer. A surface protective film with an adhesive layer as is provided in order in the thickness direction.
〔実施例９～１１〕
　以下のこと以外は、実施例８のカバーフィルム付き光学フィルムと同様にして、実施例９～１１の各カバーフィルム付き光学フィルムを作製した。 [Examples 9 to 11]
Optical films with cover films of Examples 9 to 11 were produced in the same manner as the optical film with cover film of Example 8 except for the following.
　実施例９では、厚さ３１μｍの偏光フィルムに代えて厚さ５１μｍの偏光フィルムを用いた。 In Example 9, a polarizing film with a thickness of 51 µm was used in place of the polarizing film with a thickness of 31 µm.
　実施例１０では、厚さ３１μｍの偏光フィルムに代えて厚さ２５μｍの偏光フィルムを用いた。 In Example 10, a polarizing film with a thickness of 25 μm was used in place of the polarizing film with a thickness of 31 μm.
　実施例１１では、第１粘着シートの厚さを５０μｍに代えて２５μｍとした。 In Example 11, the thickness of the first adhesive sheet was changed from 50 µm to 25 µm.
〔実施例１２〕
　以下のこと以外は、実施例８のカバーフィルム付き光学フィルムと同様にして、実施例１２のカバーフィルム付き光学フィルムを作製した。第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第２ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。 [Example 12]
An optical film with a cover film of Example 12 was produced in the same manner as the optical film with a cover film of Example 8 except for the following. In the preparation of the first pressure-sensitive adhesive composition, a second polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
　実施例１２における第１粘着剤組成物の調製では、具体的には、第２ポリマー溶液に、当該ポリマー溶液中の第２アクリルベースポリマー１００質量部あたり、アクリルオリゴマー １.５質量部と、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.２６質量部と、第２架橋剤（品名「コロネートＬ」，東ソー製）０.０２質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 Specifically, in the preparation of the first pressure-sensitive adhesive composition in Example 12, the second polymer solution was added with 1.5 parts by weight of an acrylic oligomer per 100 parts by weight of the second acrylic base polymer in the polymer solution, 1 cross-linking agent (product name “Nyper BMT-40SV”, manufactured by NOF) 0.26 parts by mass, second cross-linking agent (product name “Coronate L”, manufactured by Tosoh) 0.02 parts by mass, silane coupling agent (product name 0.3 parts by mass of "KBM403" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed.
〔実施例１３〕
　以下のこと以外は、実施例８のカバーフィルム付き光学フィルムと同様にして、実施例１３のカバーフィルム付き光学フィルムを作製した。第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第４ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。 [Example 13]
An optical film with a cover film of Example 13 was produced in the same manner as the optical film with a cover film of Example 8 except for the following. In the preparation of the first pressure-sensitive adhesive composition, a fourth polymer solution was used in place of the first polymer solution, and a first pressure-sensitive adhesive sheet was produced using the first pressure-sensitive adhesive composition.
　実施例１３における第１粘着剤組成物の調製では、具体的には、第４ポリマー溶液に、当該ポリマー溶液中の第４アクリルベースポリマー１００質量部あたり、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.３質量部と、第３架橋剤（品名「タケネートＤ１１０Ｎ」，トリメチロールプロパンキシリレンジイソシアネート，三井化学製）０.１質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 Specifically, in the preparation of the first pressure-sensitive adhesive composition in Example 13, the fourth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name " KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass were added and mixed.
〔比較例６～９〕
　以下のこと以外は、実施例８のカバーフィルム付き光学フィルムと同様にして、比較例６～９の各カバーフィルム付き光学フィルムを作製した。 [Comparative Examples 6 to 9]
Optical films with cover films of Comparative Examples 6 to 9 were produced in the same manner as the optical film with cover film of Example 8 except for the following.
　比較例６では、第２カバーフィルムとして、厚さ３８μｍの表面保護フィルムに代えて厚さ１２５μｍの表面保護フィルムを用いた。比較例６における表面保護フィルムは、ＰＥＴフィルム（品名「ルミラーＳ１０」，東レ社製）の片面にシリコーン系剥離処理剤による剥離処理が施されたフィルムである。 In Comparative Example 6, a surface protection film with a thickness of 125 µm was used as the second cover film instead of the surface protection film with a thickness of 38 µm. The surface protective film in Comparative Example 6 is a PET film (product name: "Lumirror S10", manufactured by Toray Industries, Inc.) on one side of which is subjected to release treatment with a silicone-based release agent.
　比較例７では、第１粘着剤組成物の調製において、第１ポリマー溶液に代えて第５ポリマー溶液を用い、当該第１粘着剤組成物を用いて第１粘着シートを作製した。比較例３における第１粘着剤組成物の調製では、具体的には、第５ポリマー溶液に、当該ポリマー溶液中の第５アクリルベースポリマー１００質量部あたり、第１架橋剤（品名「ナイパーＢＭＴ-４０ＳＶ」，日本油脂製）０.３質量部と、第３架橋剤（品名「タケネートＤ１１０Ｎ」，三井化学製）０.１質量部と、シランカップリング剤（品名「ＫＢＭ４０３」，信越化学工業製）０.３質量部とを加えて混合した。 In Comparative Example 7, a fifth polymer solution was used in place of the first polymer solution in the preparation of the first pressure-sensitive adhesive composition, and the first pressure-sensitive adhesive composition was used to prepare the first pressure-sensitive adhesive sheet. Specifically, in the preparation of the first pressure-sensitive adhesive composition in Comparative Example 3, the fifth polymer solution was added with a first cross-linking agent (product name: Nyper BMT- 40SV", manufactured by NOF) 0.3 parts by mass, a third cross-linking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals) 0.1 parts by mass, and a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd. ) and 0.3 parts by mass were added and mixed.
　比較例８では、粘着剤層（第２粘着剤層）付き表面保護フィルム上の第２粘着剤層の厚さを１０μｍに代えて１μｍとした。 In Comparative Example 8, the thickness of the second pressure-sensitive adhesive layer on the surface protection film with the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) was changed from 10 µm to 1 µm.
　比較例９では、剥離フィルムＬ１（厚さ５０μｍ）の代わりに剥離フィルムＬ９を用いた。剥離フィルムＬ９は、片面がシリコーン剥離処理されたＰＥＴフィルム（品名「ダイアホイル ＭＲＦ７５」，厚さ７５μｍ，三菱ケミカル社製）である。 In Comparative Example 9, a release film L9 was used instead of the release film L1 (thickness: 50 µm). The release film L9 is a PET film (product name “Diafoil MRF75”, thickness 75 μm, manufactured by Mitsubishi Chemical Co., Ltd.) one side of which is subjected to silicone release treatment.
〈せん断貯蔵弾性率〉
　実施例１～１３および比較例１～９の各カバーフィルム付き光学フィルムにおける各粘着剤層について、次のようにして、２５℃でのせん断貯蔵弾性率を測定した。 <Shear storage modulus>
The shear storage elastic modulus at 25° C. was measured as follows for each pressure-sensitive adhesive layer in each optical film with a cover film of Examples 1 to 13 and Comparative Examples 1 to 9.
　まず、測定用のサンプルを作製した。具体的には、複数の粘着剤層片を貼り合わせて約１.５ｍｍの厚さの粘着剤シートを作製した後、当該シートを打抜いて、測定用サンプルである円柱状のペレット（直径７.９ｍｍ）を得た。そして、測定用サンプルについて、動的粘弾性測定装置（商品名「Advanced Rheometric Expansion System (ARES)」，Rheometric Scientific社製）を使用して、直径７.９ｍｍのパラレルプレートの治具に固定した後に動的粘弾性測定を行った。本測定において、測定モードをねじりモードとし、測定温度範囲を－５０℃～１５０℃とし、昇温速度を５℃/分とし、周波数を１Ｈｚとした。測定結果から、２５℃におけるせん断貯蔵弾性率Ｇ’を読み取った。表１～４には、第１粘着剤層の２５℃でのせん断貯蔵弾性率Ｇ’を２５℃での貯蔵弾性率Ｍ１（ｋＰａ）として示し、第２粘着剤層の２５℃でのせん断貯蔵弾性率Ｇ’を２５℃での貯蔵弾性率Ｍ２（ｋＰａ）として示し、Ｍ２に対するＭ１の比率も示す。 First, we prepared a sample for measurement. Specifically, after laminating a plurality of adhesive layer pieces to prepare an adhesive sheet with a thickness of about 1.5 mm, the sheet is punched to obtain a cylindrical pellet (diameter 7 .9 mm). Then, the measurement sample was fixed to a parallel plate jig with a diameter of 7.9 mm using a dynamic viscoelasticity measuring device (trade name "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific). Dynamic viscoelasticity measurements were performed. In this measurement, the measurement mode was the torsion mode, the measurement temperature range was -50° C. to 150° C., the temperature increase rate was 5° C./min, and the frequency was 1 Hz. From the measurement results, the shear storage modulus G' at 25°C was read. Tables 1 to 4 show the shear storage modulus G' of the first pressure-sensitive adhesive layer at 25°C as the storage modulus M1 (kPa) at 25°C, and the shear storage modulus of the second pressure-sensitive adhesive layer at 25°C. The elastic modulus G′ is given as the storage modulus M2 (kPa) at 25° C. and the ratio of M1 to M2 is also given.
　〈剥離力〉
　実施例１～７および比較例１～５の各カバーフィルム付き光学フィルムについて、第１カバーフィルムを第１粘着剤層から剥離するための剥離力（第１剥離力）と、第２カバーフィルムを第２粘着剤層から剥離するための剥離力（第２剥離力）とを調べた。具体的には、次のとおりである。 <Peel strength>
For each optical film with a cover film of Examples 1 to 7 and Comparative Examples 1 to 5, the peel force (first peel force) for peeling the first cover film from the first pressure-sensitive adhesive layer and the second cover film The peeling force (second peeling force) for peeling from the second pressure-sensitive adhesive layer was investigated. Specifically, it is as follows.
　まず、カバーフィルム付き光学フィルムから、測定用の試験片（短辺２５ｍｍ×長辺１５０ｍｍ程度）を切り出した。次に、引張試験機（品名「オートグラフ」，島津製作所製）の固定用テーブルに試験片を固定した。具体的には、試験片から一方のカバーフィルム（第２カバーフィルムまたは第１カバーフィルム）を剥離して外した後、当該剥離によって露出した粘着剤層を介して、当該試験片を固定用テーブルに貼り付けた。次に、試験片の露出面側に位置する他方のカバーフィルム（第１カバーフィルムまたは第２カバーフィルム）に、把持用テープを貼り付けた。この把持用テープは強粘着面を有し、当該強粘着面を介して把持用テープを試験片のカバーフィルムに貼り付けた。次に、引張試験機により、試験片における粘着剤層のカバーフィルムを当該粘着剤層から剥離する剥離試験を実施し、剥離強度を剥離力として測定した。本測定では、測定温度を２５℃とし、把持用テープを引っ張ることによってカバーフィルムを剥離し、剥離角度を１８０°とし、引張速度を３００ｍｍ／分とし、剥離長さを１００ｍｍとした。測定された剥離力Ｆ１,Ｆ２（ｇｆ/２５ｍｍ）を表１,２に示す。また、剥離力Ｆ２に対する剥離力Ｆ１の比率も、表１,２に示す。剥離力Ｆ１,Ｆ２は、剥離長さ２０～１００ｍｍ（剥離強度が、剥離開始時の剥離開始力を経た後に安定している）における剥離強度の平均値である。 First, a test piece for measurement (about 25 mm short side x 150 mm long side) was cut out from the optical film with the cover film. Next, the test piece was fixed to a fixing table of a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation). Specifically, after peeling and removing one cover film (second cover film or first cover film) from the test piece, the test piece is fixed to the table through the adhesive layer exposed by the peeling. pasted on. Next, a gripping tape was attached to the other cover film (first cover film or second cover film) located on the exposed surface side of the test piece. This gripping tape had a strong adhesive surface, and the gripping tape was attached to the cover film of the test piece via the strong adhesive surface. Next, using a tensile tester, a peel test was conducted in which the cover film of the pressure-sensitive adhesive layer in the test piece was peeled off from the pressure-sensitive adhesive layer, and the peel strength was measured as the peel force. In this measurement, the measurement temperature was 25° C., the cover film was peeled off by pulling the gripping tape, the peeling angle was 180°, the pulling speed was 300 mm/min, and the peeling length was 100 mm. Tables 1 and 2 show the measured peel forces F1 and F2 (gf/25 mm). Tables 1 and 2 also show the ratio of the peeling force F1 to the peeling force F2. The peel strengths F1 and F2 are average values of the peel strength at a peel length of 20 to 100 mm (the peel strength is stable after passing through the peel initiation force at the start of peeling).
　一方、実施例８～１３および比較例６～９の各カバーフィルム付き光学フィルムについて、第１カバーフィルムを第１粘着剤層から剥離するための剥離力（第１剥離力）と、第２粘着剤層付き第２カバーフィルムを偏光フィルムから剥離するための剥離力（第２剥離力）とを調べた。具体的には、次のとおりである。 On the other hand, for each optical film with a cover film of Examples 8 to 13 and Comparative Examples 6 to 9, the peel force (first peel force) for peeling the first cover film from the first adhesive layer and the second adhesive The peeling force (second peeling force) for peeling the second cover film with the agent layer from the polarizing film was investigated. Specifically, it is as follows.
　まず、カバーフィルム付き光学フィルムから、測定用の試験片（短辺２５ｍｍ×長辺１５０ｍｍ程度）を切り出した。次に、引張試験機（品名「オートグラフ」，島津製作所製）の固定用テーブルに試験片を固定した。具体的には、第１剥離力測定用の試験片については、その第２カバーフィルム側を、強粘着の両面テープにより、固定用テーブルに貼り合わせた。第２剥離力測定用の試験片については、当該試験片から第１カバーフィルムを剥離して外した後、当該剥離によって露出した第１粘着剤層を介して、当該試験片を固定用テーブルに貼り付けた。次に、試験片の露出面側に位置するカバーフィルム（第１カバーフィルムまたは第２カバーフィルム）に、把持用テープを貼り付けた。この把持用テープは強粘着面を有し、当該強粘着面を介して把持用テープを試験片のカバーフィルムに貼り付けた。次に、引張試験機により、カバーフィルム（第１カバーフィルムまたは粘着剤層付き第２カバーフィルム）を剥離する剥離試験を実施し、剥離強度を剥離力として測定した。本測定では、測定温度を２５℃とし、把持用テープを引っ張ることによってカバーフィルムを剥離し、剥離角度を１８０°とし、引張速度を３００ｍｍ／分とし、剥離長さを１００ｍｍとした。測定された剥離力Ｆ１,Ｆ２（ｇｆ/２５ｍｍ）を表１,２に示す。また、剥離力Ｆ２に対する剥離力Ｆ１の比率も、表１,２に示す。剥離力Ｆ１,Ｆ２は、剥離長さ２０～１００ｍｍ（剥離強度が、剥離開始時の剥離開始力を経た後に安定している）における剥離強度の平均値である。 First, a test piece for measurement (about 25 mm short side x 150 mm long side) was cut out from the optical film with the cover film. Next, the test piece was fixed to a fixing table of a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation). Specifically, the second cover film side of the test piece for measuring the first peel strength was attached to a fixing table with a strong adhesive double-faced tape. For the test piece for measuring the second peel force, after peeling and removing the first cover film from the test piece, the test piece is placed on the fixing table through the first adhesive layer exposed by the peeling. pasted. Next, a gripping tape was attached to the cover film (first cover film or second cover film) positioned on the exposed surface side of the test piece. This gripping tape had a strong adhesive surface, and the gripping tape was attached to the cover film of the test piece via the strong adhesive surface. Next, using a tensile tester, a peel test was carried out by peeling the cover film (the first cover film or the second cover film with the pressure-sensitive adhesive layer), and the peel strength was measured as the peel force. In this measurement, the measurement temperature was 25° C., the cover film was peeled off by pulling the gripping tape, the peeling angle was 180°, the pulling speed was 300 mm/min, and the peeling length was 100 mm. Tables 1 and 2 show the measured peel forces F1 and F2 (gf/25 mm). Tables 1 and 2 also show the ratio of the peeling force F1 to the peeling force F2. The peel strengths F1 and F2 are average values of the peel strength at a peel length of 20 to 100 mm (the peel strength is stable after passing through the peel initiation force at the start of peeling).
〈第１カバーフィルム剥離時の第２カバーフィルムの剥離抑制〉
　実施例１～１３および比較例１～９における各カバーフィルム付き光学フィルムについて、第１カバーフィルム剥離時の第２カバーフィルムの剥離のしにくさを調べた。具体的には、まず、カバーフィルム付き光学フィルムごとに１０枚の評価サンプルを作製した。次に、各評価サンプルの第１カバーフィルムを剥離した。剥離には、引張試験機（品名「オートグラフ」，島津製作所製）を使用した。剥離においては、剥離角度を１８０°とし、引張速度を３００ｍｍ／分とした。そして、第２粘着剤層からの第２カバーフィルムの剥離（実施例１～８,比較例１～５）または偏光フィルムからの第２粘着剤層付き第２カバーフィルムの剥離（実施例９～１３,比較例６～９）を生じずに第１カバーフィルムだけを適切に剥離できた評価サンプルの数が１０である場合を“優”と評価し、７～９である場合を“良”と評価し、０～６である場合を“不良”と評価した。評価結果を表１に示す。 <Suppression of peeling of the second cover film when peeling the first cover film>
Regarding the optical films with cover films in Examples 1 to 13 and Comparative Examples 1 to 9, the difficulty of peeling the second cover film when peeling the first cover film was examined. Specifically, first, ten evaluation samples were produced for each optical film with a cover film. Next, the first cover film of each evaluation sample was peeled off. For peeling, a tensile tester (product name: "Autograph", manufactured by Shimadzu Corporation) was used. For peeling, the peeling angle was 180° and the tensile speed was 300 mm/min. Then, peeling of the second cover film from the second adhesive layer (Examples 1 to 8, Comparative Examples 1 to 5) or peeling of the second cover film with the second adhesive layer from the polarizing film (Examples 9 to 13, Comparative Examples 6 to 9) were evaluated as "excellent" when the number of evaluation samples in which only the first cover film was properly peeled off was 10, and "good" when the number was 7 to 9. , and the case of 0 to 6 was evaluated as "poor". Table 1 shows the evaluation results.
〈光学フィルムの端部クラックの抑制〉
　実施例１～１３および比較例１～９における各カバーフィルム付き光学フィルムについて、第１カバーフィルムの剥離を経た場合の、光学フィルム端部でのクラックの発生のしにくさを調べた。具体的には、まず、カバーフィルム付き光学フィルムごとに評価サンプルを作製した。次に、評価サンプルの第１カバーフィルムを、手作業によって剥離した。次に、光学フィルムの外周部（端縁から１ｍｍの領域）を光学顕微鏡によって観察した。そして、第１カバーフィルムの剥離後に光学フィルムの前記外周部に長さ１００μｍ以上のクラックが発生していない場合を“優”と評価し、長さ１００μｍ以上２００μｍ未満のクラックが発生している場合を“良”と評価し、長さ２００μｍ以上のクラックが発生している場合を“不良”と評価した。その結果を表１～４に示す。 <Suppression of edge cracks in optical film>
For the optical films with cover films in Examples 1 to 13 and Comparative Examples 1 to 9, the resistance to crack generation at the edges of the optical films after the first cover film was peeled off was examined. Specifically, first, an evaluation sample was prepared for each optical film with a cover film. Next, the first cover film of the evaluation sample was peeled off manually. Next, the outer peripheral portion of the optical film (1 mm region from the edge) was observed with an optical microscope. A case where no crack with a length of 100 μm or more occurred in the outer peripheral portion of the optical film after peeling of the first cover film was evaluated as “excellent”, and a case where a crack with a length of 100 μm or more and less than 200 μm occurred. was evaluated as "good", and a case where a crack with a length of 200 μm or more was generated was evaluated as "bad". The results are shown in Tables 1-4.
〈屈曲試験〉
　実施例１～１３および比較例１～９における各カバーフィルム付き光学フィルムについて、折り曲げ時における光学フィルムと粘着剤層との間の貼着性を調べた。具体的には、次のとおりである。 <Bending test>
The optical films with cover films in Examples 1 to 13 and Comparative Examples 1 to 9 were examined for adhesion between the optical film and the pressure-sensitive adhesive layer when folded. Specifically, it is as follows.
　まず、実施例１～７および比較例１～５の各カバーフィルム付き光学フィルムについては、第１粘着剤層から第１カバーフィルムを剥離した後、第1粘着剤層の露出面に、代替第1カバーフィルムとしてのポリイミドフィルム（厚さ８０μｍ）を貼り合わせた。そして、第２粘着剤層から第２カバーフィルムを剥離した後、第２粘着剤層の露出面に、代替第２カバーフィルムとしてのＰＥＴフィルム（厚さ１２５μｍ）を貼り合わせた。一方、実施例８～１３および比較例６～９の各カバーフィルム付き光学フィルムについては、第１粘着剤層から第１カバーフィルムを剥離した後、第1粘着剤層の露出面に、代替第1カバーフィルムとしてのポリイミドフィルム（厚さ８０μｍ）を貼り合わせた。各貼り合わせは、２５℃の環境下において２ｋｇのローラーを１往復させる作業により、実施した。 First, for each optical film with a cover film of Examples 1 to 7 and Comparative Examples 1 to 5, after peeling the first cover film from the first pressure-sensitive adhesive layer, the exposed surface of the first pressure-sensitive adhesive layer was coated with an alternative first adhesive layer. 1 A polyimide film (thickness: 80 µm) was laminated as a cover film. Then, after peeling the second cover film from the second pressure-sensitive adhesive layer, a PET film (thickness: 125 μm) was attached as an alternative second cover film to the exposed surface of the second pressure-sensitive adhesive layer. On the other hand, for the optical films with cover films of Examples 8 to 13 and Comparative Examples 6 to 9, after peeling the first cover film from the first pressure-sensitive adhesive layer, the exposed surface of the first pressure-sensitive adhesive layer was coated with an alternative first adhesive layer. 1 A polyimide film (thickness: 80 µm) was laminated as a cover film. Each bonding was carried out by reciprocating a 2 kg roller once in an environment of 25°C.
　次に、このようにして用意された各両面カバーフィルム付き光学フィルム（偏光フィルム）から、評価用のサンプルを切り出した。具体的には、切り出されるサンプルにおいて偏光フィルムの吸収軸方向が長辺方向と平行となるように、３５ｍｍ×１００ｍｍの矩形のサンプルを、カバーフィルム付き光学フィルムから切り出した。次に、サンプルを、３５℃および０.３５ＭＰａの条件で、１５分間、オートクレーブ処理した。次に、当該サンプルについて、面状体無負荷Ｕ字伸縮試験機（ユアサシステム機器製）によって、屈曲試験を実施した。本試験では、サンプルにおける長辺方向の両端部のそれぞれに対し、サンプル端縁から２０ｍｍの範囲に屈曲治具を取り付けて、サンプルを試験機に固定した（サンプルの長辺方向の中央６０ｍｍの領域は固定されていない状態にある）。また、本試験では、サンプルの第２カバーフィルム側の面が内側となるように、曲げ半径１.３ｍｍおよび曲げ角度１８０°の屈曲形態（サンプルに作用する曲げモーメントの軸方向と偏光フィルムの吸収軸方向とが直交する形態）で同サンプルを保持し、この状態にある同サンプルを、温度２５℃および相対湿度９５％の条件の恒温恒湿槽内で、２４０時間保持した（屈曲試験）。 Next, samples for evaluation were cut out from the optical films (polarizing films) with double-sided cover films thus prepared. Specifically, a rectangular sample of 35 mm×100 mm was cut out from the optical film with the cover film so that the absorption axis direction of the polarizing film was parallel to the long side direction in the sample cut out. The samples were then autoclaved at 35° C. and 0.35 MPa for 15 minutes. Next, the sample was subjected to a flexing test using a planar object no-load U-shaped stretching tester (manufactured by Yuasa System Co., Ltd.). In this test, a bending jig was attached to a range of 20 mm from the edge of the sample to each of both ends of the sample in the long side direction, and the sample was fixed to the tester (region of 60 mm in the center of the long side of the sample is in an unfixed state). In this test, the sample was bent with a bending radius of 1.3 mm and a bending angle of 180° (the axial direction of the bending moment acting on the sample and the absorption of the polarizing film). The same sample was held in a form perpendicular to the axial direction), and the same sample in this state was held for 240 hours in a thermo-hygrostat at a temperature of 25° C. and a relative humidity of 95% (bending test).
　このような屈曲試験後のサンプルを目視で観察し、屈曲部分における光学フィルム（偏光フィルム）と各カバーフィルムとの間での剥がれの有無を確認した。剥がれが確認されたサンプルでは、いずれも、サンプル短辺方向の端部から剥がれ（空隙部）が生じていた。剥がれが確認されたサンプルついては、同サンプル短辺方向における空隙部の長さ（ｍｍ）を測定した。そして、折り曲げ時における光学フィルムと粘着剤層との間の貼着性（光学フィルムと粘着剤層との間の剥がれが抑制される程度）について、前記空隙部長さが１ｍｍ未満である場合を“優”と評価し、前記空隙部長さが１ｍｍ以上２ｍｍ未満である場合を“良”と評価し、前記空隙部長さが２ｍｍ以上である場合を“不良”と評価した。
その評価結果を表１に示す。 After such a bending test, the samples were visually observed to confirm the presence or absence of peeling between the optical film (polarizing film) and each cover film at the bent portion. In all samples in which peeling was confirmed, peeling (void) occurred from the ends in the short side direction of the sample. As for the samples in which peeling was confirmed, the length (mm) of the gap in the short side direction of the sample was measured. Regarding the adhesion between the optical film and the pressure-sensitive adhesive layer at the time of bending (the extent to which peeling between the optical film and the pressure-sensitive adhesive layer is suppressed), the case where the length of the gap is less than 1 mm is defined as " A case where the length of the void was 1 mm or more and less than 2 mm was evaluated as "Good", and a case where the length of the void was 2 mm or more was evaluated as "Poor".
Table 1 shows the evaluation results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上述の実施形態は本発明の例示であり、当該実施形態によって本発明を限定的に解釈してはならない。当該技術分野の当業者によって明らかな本発明の変形例は、後記の請求の範囲に含まれる。 The above-described embodiments are examples of the present invention, and the present invention should not be construed to be limited by the embodiments. Variations of the invention that are obvious to those skilled in the art are included in the following claims.
　本発明のカバーフィルム付き光学フィルムは、例えば、フォルダブルディスプレイパネルの製造過程において、同パネルの積層構造に含まれる光学フィルムの供給材として用いられる。 The optical film with cover film of the present invention is used, for example, as a supply material for the optical film included in the laminated structure of the foldable display panel in the manufacturing process of the same panel.
Ｘ１，Ｘ２　光学フィルム（カバーフィルム付き光学フィルム）
Ｙ１，Ｙ２　粘着剤層付き光学フィルム
Ｔ　　　　　厚さ方向
１０　　　　光学フィルム
１１　　　　第１面
１２　　　　第２面
２０　　　　粘着剤層（第１粘着剤層）
２１，３１　粘着面
３０　　　　粘着剤層（第２粘着剤層）
４０　　　　カバーフィルム（第１カバーフィルム）
５０，６０　カバーフィルム（第２カバーフィルム） X1, X2 optical film (optical film with cover film)
Y1, Y2 Optical film T with adhesive layer Thickness direction 10 Optical film 11 First surface 12 Second surface 20 Adhesive layer (first adhesive layer)
21, 31 Adhesive surface 30 Adhesive layer (second adhesive layer)
40 cover film (first cover film)
50, 60 cover film (second cover film)

Claims (8)

  1. 　第１カバーフィルムと、第１粘着剤層と、光学フィルムと、第２粘着剤層と、第２カバーフィルムとを厚さ方向にこの順で備える、カバーフィルム付き光学フィルムであって、
    　前記光学フィルムが１００μｍ以下の第１厚さを有し、
    　前記第１粘着剤層が５μｍ以上１００μｍ以下の第２厚さを有し、
    　前記第１粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第１せん断貯蔵弾性率を有し、
    　前記第２粘着剤層が５μｍ以上１００μｍ以下の第３厚さを有し、
    　前記第２粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第２せん断貯蔵弾性率を有し、
    　前記第１カバーフィルムが４０μｍ以上８０μｍ以下の第４厚さを有し、
    　前記第２カバーフィルムが４０μｍ以上８０μｍ以下の第５厚さを有し、
    　前記第５厚さに対する前記第４厚さの比率が１以下であり、
    　前記第１カバーフィルムを前記第１粘着剤層から剥離するための第１剥離力の、前記第２カバーフィルムを前記第２粘着剤層から剥離するための第２剥離力に対する比率が、０.９以下であり、
    　前記第１剥離力が１０ｇｆ/２５ｍｍ以下である、カバーフィルム付き光学フィルム。     An optical film with a cover film, comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction,
    the optical film has a first thickness of 100 μm or less;
    The first adhesive layer has a second thickness of 5 μm or more and 100 μm or less,
    The first pressure-sensitive adhesive layer has a first shear storage modulus of 20 kPa or more and 100 kPa or less at 25° C.,
    The second adhesive layer has a third thickness of 5 μm or more and 100 μm or less,
    The second pressure-sensitive adhesive layer has a second shear storage modulus of 20 kPa or more and 100 kPa or less at 25°C,
    the first cover film has a fourth thickness of 40 μm or more and 80 μm or less;
    the second cover film has a fifth thickness of 40 μm or more and 80 μm or less;
    A ratio of the fourth thickness to the fifth thickness is 1 or less,
    The ratio of the first peel force for peeling the first cover film from the first adhesive layer to the second peel force for peeling the second cover film from the second adhesive layer is 0. is 9 or less,
    An optical film with a cover film, wherein the first peel force is 10 gf/25 mm or less.
  2. 　前記第３厚さに対する前記第２厚さの比率が０.１以上２以下である、請求項１に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 1, wherein the ratio of said second thickness to said third thickness is 0.1 or more and 2 or less.
  3. 　前記第２せん断貯蔵弾性率に対する前記第１せん断貯蔵弾性率の比率が０.５以上である、請求項１に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 1, wherein the ratio of said first shear storage modulus to said second shear storage modulus is 0.5 or more.
  4. 　第１カバーフィルムと、第１粘着剤層と、光学フィルムと、第２粘着剤層と、第２カバーフィルムとを厚さ方向にこの順で備える、カバーフィルム付き光学フィルムであって、
    　前記光学フィルムが１００μｍ以下の第１厚さを有し、
    　前記第１粘着剤層が５μｍ以上１００μｍ以下の第２厚さを有し、
    　前記第１粘着剤層が、２５℃において２０ｋＰａ以上１００ｋＰａ以下の第１せん断貯蔵弾性率を有し、
    　前記第２粘着剤層が５μｍ以上３０μｍ以下の第３厚さを有し、
    　前記第２粘着剤層が、２５℃において１５０ｋＰａ以上の第２せん断貯蔵弾性率を有し、
    　前記第１カバーフィルムが４０μｍ以上８０μｍ以下の第４厚さを有し、
    　前記第２カバーフィルムが４０μｍ以上８０μｍ以下の第５厚さを有し、
    　前記第５厚さに対する前記第４厚さの比率が１以上であり、
    　前記第２粘着剤層および前記第２カバーフィルムが、第２粘着剤層付き第２カバーフィルムを形成し、
    　前記第１カバーフィルムを前記第１粘着剤層から剥離するための第１剥離力の、前記第２粘着剤層付き第２カバーフィルムを前記光学フィルムから剥離するための第２剥離力に対する比率が、０.９以下であり、
    　前記第１剥離力が１０ｇｆ/２５ｍｍ以下である、カバーフィルム付き光学フィルム。     An optical film with a cover film, comprising a first cover film, a first pressure-sensitive adhesive layer, an optical film, a second pressure-sensitive adhesive layer, and a second cover film in this order in the thickness direction,
    the optical film has a first thickness of 100 μm or less;
    The first adhesive layer has a second thickness of 5 μm or more and 100 μm or less,
    The first pressure-sensitive adhesive layer has a first shear storage modulus of 20 kPa or more and 100 kPa or less at 25° C.,
    The second adhesive layer has a third thickness of 5 μm or more and 30 μm or less,
    The second pressure-sensitive adhesive layer has a second shear storage modulus of 150 kPa or more at 25° C.,
    the first cover film has a fourth thickness of 40 μm or more and 80 μm or less;
    the second cover film has a fifth thickness of 40 μm or more and 80 μm or less;
    A ratio of the fourth thickness to the fifth thickness is 1 or more,
    The second pressure-sensitive adhesive layer and the second cover film form a second pressure-sensitive adhesive layer-attached second cover film,
    The ratio of the first peel force for peeling the first cover film from the first pressure-sensitive adhesive layer to the second peel force for peeling the second cover film with the second pressure-sensitive adhesive layer from the optical film is , is less than or equal to 0.9, and
    An optical film with a cover film, wherein the first peel force is 10 gf/25 mm or less.
  5. 　前記第３厚さに対する前記第２厚さの比率が１以上１００以下である、請求項４に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 4, wherein the ratio of said second thickness to said third thickness is 1 or more and 100 or less.
  6. 　前記第２せん断貯蔵弾性率に対する前記第１せん断貯蔵弾性率の比率が０.５以下である、請求項４に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 4, wherein the ratio of said first shear storage modulus to said second shear storage modulus is 0.5 or less.
  7. 　前記光学フィルムが偏光フィルムである、請求項１に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 1, wherein the optical film is a polarizing film.
  8. 　前記偏光フィルムが１.０×１０６ｋＰａ以上の第３せん断貯蔵弾性率を有する、請求項７に記載のカバーフィルム付き光学フィルム。 The optical film with a cover film according to claim 7, wherein the polarizing film has a third shear storage elastic modulus of 1.0 x 106 kPa or more.
PCT/JP2022/023779 2021-06-30 2022-06-14 Optical film with cover film WO2023276654A1 (en)

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Citations (3)

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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
JP2016080830A (en) * 2014-10-15 2016-05-16 日東電工株式会社 Optical film with double-side adhesive, method for manufacturing image display device using the optical film, and method for suppressing curl in optical film with double-side adhesive
JP2020157577A (en) * 2019-03-26 2020-10-01 住友化学株式会社 Laminate and display device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020190754A (en) 2020-08-18 2020-11-26 日東電工株式会社 Optical film, removal method and manufacturing method of optical display panel

Patent Citations (3)

* 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
JP2016080830A (en) * 2014-10-15 2016-05-16 日東電工株式会社 Optical film with double-side adhesive, method for manufacturing image display device using the optical film, and method for suppressing curl in optical film with double-side adhesive
JP2020157577A (en) * 2019-03-26 2020-10-01 住友化学株式会社 Laminate and display device

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