WO2024116892A1 - Laminate and display device - Google Patents

Laminate and display device Download PDF

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Publication number
WO2024116892A1
WO2024116892A1 PCT/JP2023/041404 JP2023041404W WO2024116892A1 WO 2024116892 A1 WO2024116892 A1 WO 2024116892A1 JP 2023041404 W JP2023041404 W JP 2023041404W WO 2024116892 A1 WO2024116892 A1 WO 2024116892A1
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Prior art keywords
optical film
range
acrylate
meth
film
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PCT/JP2023/041404
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French (fr)
Japanese (ja)
Inventor
奈々恵 藤枝
啓人 小長
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コニカミノルタ株式会社
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Publication of WO2024116892A1 publication Critical patent/WO2024116892A1/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
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/111—Anti-reflection coatings using layers comprising organic materials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements

Definitions

  • the present invention relates to a laminate and a display device. More specifically, the present invention relates to a laminate that achieves both suppression of external light reflection and good contrast after bending.
  • Flexible displays consist of a display unit and a cover unit that protects the display unit.
  • the substrate used in the cover unit is required to have flexibility. Therefore, it has been considered to change the conventionally used glass substrate to a resin substrate or to make the glass substrate itself thinner.
  • thin-film glass Ultra Thin Glass: UTG
  • UTG Ultra Thin Glass
  • a technique is known in which a protective film is attached to the thin film glass to improve impact resistance when used in a cover unit.
  • displays have a problem with external light reflection. More specifically, external light passes through the cover unit and is reflected on the surface of the metal substrate in the display unit, and the reflected light is perceived by the viewer, which makes it difficult to correctly view images and videos displayed on the display.
  • Two possible methods for solving this problem are: 1) weakening the intensity of external light that reaches the metal substrate in the display unit, and 2) weakening the intensity of light reflected from the surface of the metal substrate before it is visually recognized. In other words, it is preferable to weaken the intensity of external light that passes through the cover unit and the intensity of reflected light that passes through the cover unit and is visually recognized, and a method of imparting optical properties to the protective film is being considered.
  • Patent Document 1 proposes a self-luminous display device that suppresses scattering of light reflected from the substrate and simplifies the layer structure by making the sealing material placed on the substrate on which the light-emitting elements are mounted black.
  • this technology is related to the sealing material, and not to the film that protects the thin glass. Furthermore, this technology does not sufficiently suppress external light reflection, and further improvements are required.
  • the present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a laminate and a display device that achieve both suppression of external light reflection and good contrast after bending.
  • the present inventors have investigated the causes of the above problems in order to solve the above problems, and have found that, in a laminate having at least an optical film A, an optical film B, and a glass layer, a laminate can be provided which achieves both suppression of external light reflection and good contrast after bending by arranging the optical film A, the glass layer, and the optical film B in this order, setting the average light transmittances T A and T B of the optical film A and the optical film B in the wavelength region of 380 to 780 nm within specific ranges, and making T A larger than T B , thereby completing the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.
  • the T A and the T B satisfy the following formula (1) and both the T A and the T B are within a range of 39 to 89%.
  • a laminate comprising:
  • the laminate further has an adhesive layer C,
  • the optical film A, the glass layer, the optical film B, and the adhesive layer C are arranged in this order,
  • T C the average light transmittance of the adhesive layer C in the wavelength region of 380 to 780 nm
  • T B and the T C satisfy the following formula (2): T B ⁇ T C 3.
  • the laminate further has an adhesive layer D, The optical film A, the glass layer, the adhesive layer D, and the optical film B are arranged in this order, 3.
  • a display device comprising the laminate according to claim 1 or 2.
  • the above-mentioned means of the present invention make it possible to provide a laminate and a display device that achieve both suppression of external light reflection and good contrast after bending.
  • the laminate of the present invention is a laminate having an optical film and thin glass (glass layer), and is configured such that the optical film is bonded to both sides of the thin glass. It is believed that this configuration can protect the thin glass, which is vulnerable to impacts and easily breaks.
  • the intensity of light that reaches (is incident on) the surface of the thin glass can be weakened by lowering the average light transmittance (hereinafter simply referred to as "light transmittance") of optical film A in the wavelength range of 380 to 780 nm.
  • the intensity of light that reaches the surface of the metal substrate can be weakened by lowering the light transmittance of optical film A and optical film B. Therefore, by making the light transmittance of optical film A and optical film B relatively low, specifically, 89% or less, it is possible to suppress external light reflection on the thin glass and metal substrate.
  • optical film A is disposed on the most visible side, the intensity of light that reaches (enters) the surface of optical film A cannot be weakened. For this reason, the intensity of reflected light can be weakened by relatively increasing the light transmittance of optical film A. Therefore, by making the light transmittance of optical film A higher than that of optical film B, external light reflection at optical film A and thin glass can be efficiently suppressed. However, when the external light transmitted through optical film A reaches the metal substrate, the visibility is deteriorated due to the reflection of the external light from the metal substrate.
  • the transmittance of optical film B which is closer to the metal substrate, is made lower than the transmittance of optical film A, thereby making it possible to efficiently suppress the reflection of the external light on the metal substrate.
  • optical film A and optical film B are made too low, the light from the light-emitting elements in the display unit cannot be sufficiently transmitted to the viewing side. Therefore, by allowing optical film A and optical film B to transmit light appropriately, good contrast can be obtained in the display device.
  • the laminate of the present invention is used in a foldable display device (flexible display), it is necessary that the display device obtain good contrast even after repeated folding (bending).
  • the inventors found that by setting the light transmittance of optical film A and optical film B to 39% or more, good contrast can be obtained even in the display device after repeated folding.
  • 1 is a cross-sectional view of a basic layer structure of a laminate of the present invention.
  • 1 is a cross-sectional view of a basic layer structure of a laminate of the present invention.
  • 1 is a cross-sectional view of a basic layer structure of a laminate of the present invention.
  • Schematic diagram showing an example of a method for producing thin glass An example of application of the present invention to an organic EL display, which is an example of a display device.
  • An example of application of the present invention to an organic EL display which is an example of a display device.
  • the laminate of the present invention is a laminate having at least an optical film A, an optical film B, and a glass layer, and is arranged in the order of the optical film A, the glass layer, and the optical film B, and is characterized in that, when the average light transmittances of the optical film A and the optical film B in a wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within the range of 39 to 89%.
  • the T A is preferably within the range of 70 to 85%.
  • the T B is preferably within the range of 70 to 85%.
  • At least the optical film B contains rubber particles.
  • the content of the rubber particles is within the range of 10 to 80 mass % relative to the total mass of the optical film B.
  • the optical film B contains a thermoplastic (meth)acrylic resin.
  • the thickness of the optical film B is within the range of 15 to 50 ⁇ m.
  • the thickness of the glass layer is within the range of 10 to 30 ⁇ m.
  • the laminate further has an adhesive layer C, and is arranged in the order of the optical film A, the glass layer, the optical film B, and the adhesive layer C, and when the average light transmittance of the adhesive layer C in a wavelength region of 380 to 780 nm is T C , the T B and the T C satisfy the following formula (2). Equation (2): TB ⁇ TC
  • the laminate further includes an adhesive layer D, and that the optical film A, the glass layer, the adhesive layer D, and the optical film B are arranged in this order, and that the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
  • the display device of the present invention is characterized by comprising the laminate of the present invention.
  • the optical film A is disposed closer to the viewing side of the display device than the optical film B.
  • the laminate of the present invention is a laminate having at least an optical film A, an optical film B, and a glass layer, which is arranged in the order of the optical film A, the glass layer, and the optical film B, and is characterized in that, when the average light transmittances of the optical film A and the optical film B in a wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within the range of 39 to 89%.
  • optical film refers to a film that has an optical function in which, as one of several functions of the film, the average light transmittance in the wavelength range of 380 to 780 nm is within the range of 39 to 89%.
  • the laminate 10 has an optical film A1, a glass layer 3, and an optical film B2.
  • 2 and 3 are cross-sectional views of the basic layer structure of the laminate of the present invention when an adhesive layer is included.
  • the laminate 20 includes an optical film A1, a glass layer 3, an optical film B2, and an adhesive layer C4.
  • the laminate 30 includes an optical film A1, a glass layer 3, an adhesive layer D5, an optical film B2, and an adhesive layer C4.
  • the boundary between the adhesive layer C4 and the optical film B2 does not necessarily have to be clear, and the adhesive layer C4 and the optical film B2 may be integrated into a layer structure.
  • the boundary between the adhesive layer D5 and the optical film B2 does not necessarily have to be clear, and the adhesive layer D5 and the optical film B2 may be integrated into a layer structure.
  • both sides of the thin glass (glass layer) are protected with an optical film, and the optical transmittance of the optical film is set within a specific range. This makes it possible to achieve both suppression of external light reflection and good contrast after bending when the laminate of the present invention is used as a cover unit.
  • the laminate of the present invention has at least an optical film A, an optical film B, and a glass layer. If necessary, it may have an adhesive layer or the like.
  • the adhesive layer is preferably an adhesive layer C or an adhesive layer D described later, but is not particularly limited. Each layer will be described below.
  • Optical Film A and optical film B according to the present invention are characterized in that, when average light transmittances in a wavelength region of 380 to 780 nm are T A and T B , respectively, T A and T B satisfy the following formula (1) and both T A and T B are within the range of 39 to 89%.
  • optical film A and optical film B may or may not be the same.
  • the light transmittance of an optical film can be adjusted by adding a colorant to the optical film. It can also be adjusted by the type and content of the materials (resin, rubber particles, etc.) that make up the optical film.
  • the optical film according to the present invention is preferably made of a resin, and further preferably contains rubber particles, a colorant, fine particles, etc., as necessary.
  • Resin for Optical Film is not particularly limited, and examples thereof include cellulose ester, cycloolefin-based resin, fumaric acid diester-based resin, polypropylene, (meth)acrylic resin, polyester, polyarylate, polyimide, styrene-based resin, and composite resin thereof.
  • a linear polymer material having a carbonyl group in the side chain or a polymer material having a cyclic structure in the main chain.
  • a (meth)acrylic resin, a styrene-(meth)acrylate copolymer, a cycloolefin resin, a polyimide, or a cellulose ester it is preferable to contain a linear polymer material having a carbonyl group in the side chain, or a polymer material having a cyclic structure in the main chain.
  • a (meth)acrylic resin a styrene-(meth)acrylate copolymer, a cycloolefin resin, a polyimide, or a cellulose ester.
  • the (meth)acrylic resin preferably has at least a structural unit (U1) derived from methyl methacrylate.
  • the thermoplastic (meth)acrylic resin preferably further has a structural unit (U2) derived from phenylmaleimide.
  • the (meth)acrylic resin may further have structural units other than those described above. From the viewpoint of imparting toughness to the optical film, it is more preferable that the (meth)acrylic resin further has a structural unit (U3) derived from an alkyl acrylate ester.
  • thermoplastic (meth)acrylic resin preferably has a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and a structural unit (U3) derived from an alkyl acrylate.
  • the content of the structural unit (U1) derived from methyl methacrylate is preferably within the range of 50 to 95% by mass, and more preferably within the range of 70 to 90% by mass, relative to all structural units constituting the (meth)acrylic resin.
  • the structural unit (U2) derived from phenylmaleimide has a relatively rigid structure, and therefore can increase the mechanical strength of the optical film.
  • the structural unit (U2) derived from phenylmaleimide has a relatively bulky structure, that is, it has microscopic voids in the resin matrix through which the rubber particles can move. This makes it easier to concentrate the rubber particles in the surface layer of the optical film. The rubber particles will be described in more detail later.
  • the content of the structural unit (U2) derived from phenylmaleimide is preferably within a range of 1 to 25 mass%, and more preferably within a range of 7 to 15 mass%, based on all structural units constituting the (meth)acrylic resin.
  • the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, the optical film has excellent storage stability in a high humidity environment, and when the content is 25% by mass or less, the optical film can have sufficient toughness.
  • the structural unit (U3) derived from an alkyl acrylate ester can impart moderate flexibility to the resin. Therefore, for example, by combining it with the structural unit (U2) derived from phenylmaleimide, sufficient toughness can be imparted to the optical film.
  • the alkyl acrylate is preferably an alkyl acrylate having 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms in the alkyl portion.
  • acrylic acid alkyl esters include methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), propyl acrylate (propyl acrylate), butyl acrylate (butyl acrylate), 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate), hexyl acrylate (hexyl acrylate), and 2-ethylhexyl acrylate (2-ethylhexyl acrylate).
  • the content of the structural unit (U3) derived from an alkyl acrylate is preferably within a range of 1 to 25 mass%, and more preferably within a range of 5 to 15 mass%, based on all structural units constituting the (meth)acrylic resin.
  • the content of the structural unit (U3) derived from an alkyl acrylate of 1% by mass or more can provide the (meth)acrylic resin with appropriate flexibility and can suppress breakage of the optical film, while the content of the structural unit (U3) derived from an alkyl acrylate of 25% by mass or less can suppress a decrease in the glass transition temperature (Tg) of the (meth)acrylic resin and can provide the optical film with excellent storage stability under high humidity conditions.
  • Tg glass transition temperature
  • the ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from an alkyl acrylate is preferably within the range of 20 to 70% by mass. When this ratio is 20% by mass or more, it is easy to increase the storage modulus of the optical film, and when it is 70% by mass or less, sufficient toughness can be imparted to the optical film.
  • the glass transition temperature (Tg) of the (meth)acrylic resin is preferably 100°C or higher, and more preferably within the range of 120 to 150°C. By keeping it within the above range, the heat resistance of the optical film can be improved.
  • Tg of the (meth)acrylic resin it is preferable to adjust the content of, for example, the structural unit (U2) derived from phenylmaleimide or the structural unit (U3) derived from an alkyl acrylate.
  • the weight-average molecular weight (Mw) of the (meth)acrylic resin is preferably 100,000 or more, more preferably 1,000,000 or more, and even more preferably in the range of 1,500,000 to 3,000,000.
  • the toughness of the optical film can be increased. This makes it possible to prevent the optical film from breaking due to the transport tension during transport.
  • the storage modulus of the optical film can be increased, making it possible to suppress winding deformation.
  • the weight average molecular weight (Mw) of the (meth)acrylic resin can be measured by the following method.
  • the weight average molecular weight (Mw) and number average molecular weight of other resins can also be measured by the following method.
  • Styrene-(meth)acrylate copolymer Styrene-acrylic resin is synthesized by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer.
  • styrene-(meth)acrylate copolymers can impart transparency to optical films.
  • the moisture absorption expansion coefficient can be adjusted by the copolymerization ratio of the styrene portion, so curling of optical films and laminates can be controlled by adjusting the copolymerization ratio.
  • styrene monomer examples include styrene represented by the structural formula CH 2 ⁇ CH—C 6 H 5 , as well as styrene derivatives having a known side chain or functional group in the styrene structure.
  • Examples of the (meth)acrylic acid ester monomer include acrylic acid esters and methacrylic acid esters represented by CH(R 1 ) ⁇ CHCOOR 2 (R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 24 carbon atoms).
  • Other examples include acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters.
  • styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ⁇ -methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene.
  • Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate (2EHA), stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethyla
  • (meth)acrylic acid ester monomer is a general term for "acrylic acid ester monomer” and “methacrylic acid ester monomer” and means one or both of them.
  • methyl (meth)acrylate means one or both of “methyl acrylate” and “methyl methacrylate”.
  • the (meth)acrylic acid ester monomers may be used alone or in combination of two or more kinds.
  • the weight average molecular weight (Mw) of the styrene-acrylic resin is preferably within the range of 5,000 to 150,000, and more preferably within the range of 30,000 to 120,000, from the viewpoint of being able to control the plasticity.
  • the weight average molecular weight (Mw) can be measured in the same manner as for the (meth)acrylic resin described above.
  • the styrene-acrylic resin may be a commercially available product, for example, "TX320XL” (MS resin, manufactured by Denka Co., Ltd.).
  • the cycloolefin resin is preferably a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and another monomer copolymerizable with the cycloolefin monomer.
  • the cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton. Among them, a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferable.
  • R 1 to R 4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group.
  • p represents an integer of 0 to 2.
  • R 1 to R 4 do not all represent hydrogen atoms at the same time, R 1 and R 2 do not both represent hydrogen atoms, and R 3 and R 4 do not both represent hydrogen atoms.
  • the hydrocarbon group having 1 to 30 carbon atoms represented by R 1 to R 4 is, for example, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms.
  • the hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom.
  • linking groups include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond.
  • Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.
  • examples of the polar group represented by R 1 to R 4 include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, and a cyano group.
  • a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group is preferable. From the viewpoint of solubility during solution casting, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable.
  • p is preferably 1 or 2 from the viewpoint of increasing heat resistance.
  • p is 1 or 2 from the viewpoint of increasing heat resistance.
  • the resulting polymer becomes bulky and the glass transition temperature is likely to be improved.
  • it becomes somewhat responsive to humidity, making it easier to control the curl balance when formed into a laminate.
  • R5 represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms.
  • R6 represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom).
  • p represents an integer of 0 to 2.
  • R 5 in the above general formula (A-2) is preferably a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.
  • R 6 is preferably a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group, and from the viewpoint of solubility during solution casting, is more preferably an alkoxycarbonyl group or an aryloxycarbonyl group.
  • p in the above general formula (A-2) is preferably 1 or 2.
  • p is 1 or 2
  • the resulting polymer becomes bulky and the glass transition temperature is easily improved.
  • the cycloolefin monomer is preferably a cycloolefin monomer having the structure represented by the above general formula (A-2).
  • the crystallinity of an organic compound is reduced by breaking the symmetry, and the solubility in an organic solvent is improved.
  • R 5 and R 6 in general formula (A-2) are substituted on only one side of the carbon atoms constituting the ring with respect to the symmetric axis of the molecule, and therefore the symmetry of the molecule is low. That is, the cycloolefin monomer having the structure represented by general formula (A-2) is highly soluble and is therefore suitable for producing an optical film by a solution casting method.
  • the content of the cycloolefin monomer having the structure represented by general formula (A-2) in the cycloolefin resin is preferably 70 mol% or more relative to the total number of moles of all cycloolefin monomers constituting the cycloolefin resin. Also, it is more preferable that it is 80 mol% or more, and even more preferable that it is 100 mol%.
  • the content of the cycloolefin monomer having the structure represented by general formula (A-2) is 70 mol% or more, the orientation of the cycloolefin resin is increased, and the phase difference (retardation) value is likely to increase.
  • cycloolefin monomers having a structure represented by general formula (A-1) are shown as example compounds 1 to 14.
  • specific examples of cycloolefin monomers having a structure represented by general formula (A-2) are shown as example compounds 15 to 34.
  • copolymerizable monomers capable of ring-opening copolymerization include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.
  • Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, (meth)acrylates, etc.
  • Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 carbon atoms (preferably 2 to 8), such as ethylene, propylene, and butene.
  • Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene.
  • (meth)acrylates examples include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.
  • the content of the cycloolefin monomer in a copolymer of a cycloolefin monomer and a copolymerizable monomer is preferably within the range of 20 to 80 mol %, and more preferably within the range of 30 to 70 mol %, based on the total of all monomers constituting the copolymer.
  • the cycloolefin resin is a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the above general formula (A-1) or (A-2).
  • Examples of such polymers include the following.
  • Ring-opening polymer of cycloolefin monomer 1) Ring-opening polymer of cycloolefin monomer; 2) Ring-opening copolymer of cycloolefin monomer and a copolymerizable monomer capable of ring-opening copolymerization therewith; 3) Hydrogenated product of ring-opening (co)polymer of 1) or 2) above; 4) (co)polymer obtained by cyclizing ring-opening (co)polymer of 1) or 2) above by Friedel-Crafts reaction and then hydrogenating it; 5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound; 6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof; 7) Alternating copolymer of cycloolefin monomer and (meth)acrylate.
  • the polymers 1) to 7) above can all be obtained by known methods, for example, the methods described in JP-A-2008-107534 and JP-A-2005-227606.
  • the catalyst and solvent used in the ring-opening copolymerization 2) above can be, for example, those described in paragraphs 0019 to 0024 of JP-A-2008-107534.
  • the catalyst used in the hydrogenation 3) and 6) above can be, for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534.
  • the acidic compound used in the Friedel-Crafts reaction 4) above can be, for example, those described in paragraph 0029 of JP-A-2008-107534.
  • the catalyst used in the addition polymerization 5) to 7) above can be, for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606.
  • the alternating copolymerization reaction of 7) above can be carried out, for example, by the method described in paragraphs 0071 to 0072 of JP 2005-227606 A.
  • the cycloolefin resin preferably contains at least one of a structural unit represented by the following general formula (B-1) and a structural unit represented by the following general formula (B-2). It is more preferred that the cycloolefin resin contains only a structural unit represented by general formula (B-2), or contains both a structural unit represented by general formula (B-1) and a structural unit represented by general formula (B-2).
  • the structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).
  • R 1 to R 4 and p have the same meanings as R 1 to R 4 and p in the above general formula (A-1), respectively.
  • R 5 to R 6 and p have the same meanings as R 5 to R 6 and p in general formula (A-2), respectively.
  • the cycloolefin resin used in the present invention may be a commercially available product.
  • examples of commercially available cycloolefin resins include ARTON (registered trademark, the same applies below) G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900, R5000, etc.), and ARTON RX (e.g., RX4500, etc.), all manufactured by JSR Corporation.
  • the intrinsic viscosity [ ⁇ ]inh of the cycloolefin resin at 30° C. is preferably within the range of 0.2 to 5 cm 3 /g, more preferably within the range of 0.3 to 3 cm 3 /g, and even more preferably within the range of 0.4 to 1.5 cm 3 /g.
  • the number average molecular weight (Mn) of the cycloolefin resin is preferably within the range of 8,000 to 100,000, more preferably within the range of 10,000 to 80,000, and further preferably within the range of 12,000 to 50,000.
  • the weight average molecular weight (Mw) of the cycloolefin resin is preferably within a range of 20,000 to 300,000, more preferably within a range of 30,000 to 250,000, and further preferably within a range of 40,000 to 200,000.
  • the weight average molecular weight (Mw) can be measured by the same method as that for the (meth)acrylic resin described above.
  • the cycloolefin resin has good heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as an optical film.
  • the glass transition temperature (Tg) of cycloolefin resins is usually 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C. Having a Tg of 110°C or higher makes it possible to suppress deformation under high temperature conditions. On the other hand, having a Tg of 350°C or lower makes molding easier and suppresses deterioration of the resin due to heat during molding processing.
  • the content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total mass of the optical film.
  • Polyimide is synthesized by a polymerization reaction between a tetracarboxylic dianhydride and a diamine.
  • tetracarboxylic dianhydride examples include aromatic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and alicyclic tetracarboxylic dianhydrides. Among these, aromatic tetracarboxylic dianhydrides are preferred.
  • the diamine may be an aromatic diamine, an aliphatic diamine, or an alicyclic diamine, and among these, an aromatic diamine is preferred.
  • the weight average molecular weight (Mw) of the polyimide is preferably within the range of 100,000 to 300,000, and more preferably within the range of 130,000 to 250,000. By being within the above range, it is possible to prevent the optical film from breaking due to the transport tension during transport.
  • the weight average molecular weight (Mw) can be measured in the same manner as for the (meth)acrylic resin described above.
  • the polyimide content is preferably 60% by mass or more, and more preferably 70% by mass or more, based on the total mass of the optical film.
  • Cellulose ester is a polymer in which ⁇ -glucose units are linked in a linear chain via ⁇ -1,4-glycosidic bonds.
  • Cellulose ester is cellulose in which some or all of the hydrogen atoms in the hydroxyl groups (-OH) at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups.
  • the cellulose ester is not particularly limited, but is preferably an ester of a linear or branched carboxylic acid having about 2 to 22 carbon atoms.
  • the carboxylic acid constituting the ester include an aliphatic carboxylic acid, an alicyclic carboxylic acid, and an aromatic carboxylic acid.
  • Examples of the substituted acyl groups of cellulose esters include acyl groups having 2 to 22 carbon atoms, such as acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, and stearoyl.
  • the carboxylic acid (acyl group) constituting the ester may have a substituent.
  • the carboxylic acid constituting the ester is preferably a lower fatty acid having 6 or less carbon atoms, more preferably a lower fatty acid having 3 or less carbon atoms.
  • the acyl group in the cellulose ester may be of a single type or a combination of multiple acyl groups.
  • cellulose esters include cellulose acetates such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), as well as mixed fatty acid esters of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group, such as cellulose acetate propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate.
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate propionate
  • CAP cellulose acetate butyrate
  • cellulose acetate propionate butyrate cellulose acetate propionate butyrate
  • the degree of acyl substitution represents the average number of acyl groups per glucose unit, i.e., how many of the hydrogen atoms of the hydroxyl groups at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups. Therefore, the maximum degree of substitution of the acyl group is 3.0, which means that all of the hydrogen atoms of the hydroxy groups at the 2-, 3- and 6-positions are substituted with acyl groups.
  • the acyl groups may be substituted evenly at the 2-, 3- and 6-positions of one glucose unit, or may be substituted with a distribution.
  • the degree of acyl substitution can be determined by the method specified in ASTM-D817-96.
  • the substitution degree of the acyl group of the cellulose ester is too large, the retardation is difficult to be expressed, so that it is necessary to increase the stretching ratio when producing the optical film. However, it is difficult to uniformly stretch at a high stretching ratio, and the thickness of the optical film tends to vary greatly.
  • the smaller the substitution degree of the acyl group of the cellulose ester the easier it is to express the retardation, so that the thickness of the optical film can be made thin and uniform.
  • the degree of substitution of the acyl group in the cellulose ester is too small, the durability of the optical film decreases, and therefore, from the viewpoint of durability, it is preferable not to make the degree of substitution too small.
  • the humidity-dependent change in retardation (Rt, phase difference) in the thickness direction occurs when water molecules coordinate with the carbonyl groups of cellulose. Therefore, the smaller the degree of acyl group substitution, i.e., the fewer the carbonyl groups in the cellulose, the less humidity-dependent change in Rt occurs.
  • the degree of substitution of the acyl group in the cellulose ester is preferably within a range of 2.1 to 2.5, and more preferably within a range of 2.2 to 2.45.
  • environmental fluctuations particularly fluctuations in Rt due to humidity
  • the uniformity of the thickness of the optical film can be improved.
  • the flowability and stretchability during production of the optical film can be improved.
  • the degree of substitution of the acyl group of the cellulose ester satisfies both of the following formulas (a) and (b).
  • X is the degree of substitution of the acetyl group
  • Y is the degree of substitution of the propionyl group or the butyryl group, or the degree of substitution of a mixture thereof.
  • the degree of substitution X of the acetyl group of cellulose acetate preferably satisfies 2.1 ⁇ X ⁇ 2.5, and more preferably satisfies 2.15 ⁇ X ⁇ 2.45.
  • An example of cellulose acetate that satisfies the above range is cellulose diacetate (DAC).
  • the cellulose ester is preferably cellulose acetate propionate (CAP).
  • CAP cellulose acetate propionate
  • X and Y satisfy any of the following: 0.95 ⁇ X ⁇ 2.25, 0.1 ⁇ Y ⁇ 1.2, 2.15 ⁇ X+Y ⁇ 2.45.
  • cellulose acetates with different degrees of substitution may be mixed. There are no particular limitations on the mixing ratio of the different cellulose acetates.
  • the number average molecular weight (Mn) of the cellulose ester is preferably within the range of 2 ⁇ 10 4 to 3 ⁇ 10 5 , more preferably within the range of 2 ⁇ 10 4 to 1.2 ⁇ 10 5 , and even more preferably within the range of 4 ⁇ 10 4 to 8 ⁇ 10 4 .
  • the number average molecular weight (Mn) of cellulose ester can be measured in the same manner as for the (meth)acrylic resin described above.
  • the weight average molecular weight (Mw) of the cellulose ester is preferably within the range of 2 ⁇ 10 4 to 1 ⁇ 10 6 , more preferably within the range of 2 ⁇ 10 4 to 1.2 ⁇ 10 5 , and even more preferably within the range of 4 ⁇ 10 4 to 8 ⁇ 10 4 .
  • the raw cellulose for cellulose ester is not particularly limited, but examples include cotton linters, wood pulp, kenaf, etc. Furthermore, the cellulose esters obtained from these may be mixed in any desired ratio.
  • Cellulose esters such as cellulose acetate and cellulose acetate propionate can be synthesized by known methods.
  • the raw material cellulose, organic acid (acetic acid, propionic acid, etc.), acid anhydride (acetic anhydride, propionic anhydride, etc.) and catalyst (sulfuric acid, etc.) are mixed together to esterify the cellulose, and the reaction is allowed to proceed until a cellulose triester is produced.
  • mixed ester type cellulose esters such as cellulose acetate propionate and cellulose acetate butyrate.
  • the cellulose triester is then hydrolyzed to give a cellulose ester having the desired degree of acyl substitution. Thereafter, the cellulose ester is finally obtained through steps such as filtration, precipitation, washing, dehydration, drying, etc. Specifically, the cellulose ester can be synthesized by referring to the method described in JP-A-10-45804.
  • rubber particles refers to particles containing a resin that exhibits rubber elasticity at room temperature.
  • the optical film according to the present invention preferably contains rubber particles.
  • toughness flexibleibility
  • loss tangent loss tangent
  • the optical film B contains rubber particles.
  • the loss tangent (tan ⁇ B ) of the optical film B can be appropriately adjusted, and the impact resistance can be further improved.
  • the layer structure of the rubber particles according to the present invention may be a single layer structure or a multi-layer structure.
  • the resin exhibiting rubber elasticity at room temperature (hereinafter also referred to as "rubber-like polymer”) is not particularly limited.
  • the order of monomer arrangement is also not particularly limited, and may be, for example, linear, comb-like (graft type), or branched (star type).
  • the rubber-like polymer may have a structure that is partially crosslinked with a crosslinkable monomer.
  • the rubber-like polymer is preferably a soft crosslinked polymer having a glass transition temperature (Tg) of 0° C. or lower, from the viewpoint of exhibiting rubber elasticity at room temperature.
  • crosslinked polymers include butadiene-based crosslinked polymers, (meth)acrylic crosslinked polymers, organosiloxane crosslinked polymers, etc.
  • (meth)acrylic crosslinked polymers are preferred, and acrylic crosslinked polymers are more preferred, from the viewpoint of a small difference in refractive index from thermoplastic (meth)acrylic resins and less loss of transparency of the optical film.
  • the rubber particles according to the present invention are preferably particles containing an acrylic crosslinked polymer (hereinafter also referred to as an "acrylic rubber-like polymer").
  • the content of rubber particles is preferably within the range of 10 to 80% by mass relative to the total mass of the optical film.
  • the optical film has an appropriate hardness and can obtain the desired storage modulus and loss tangent (tan ⁇ ).
  • optical film B according to the present invention contains at least a combination of a (meth)acrylic resin and rubber particles of a graft copolymer.
  • the content of the (meth)acrylic resin is preferably within the range of 5 to 95% by mass relative to the total mass of the optical film. It is more preferably within the range of 10 to 60% by mass, even more preferably within the range of 10 to 50% by mass, and particularly preferably within the range of 10 to 40% by mass.
  • the content of the rubber particles is preferably within the range of 10 to 80% by mass, based on the total mass of the optical film. Also, it is more preferable that it is within the range of 20 to 60% by mass, and even more preferable that it is within the range of 20 to 50% by mass. By being within the above range, the size of the aggregates becomes sufficient and uniform, foreign matter is less likely to be mixed into the film, and an optical film with improved optical properties and mechanical properties can be obtained.
  • the rubber particles according to the present invention preferably contain an acrylic rubber-like polymer.
  • the acrylic rubber-like polymer will be referred to as "acrylic rubber-like polymer (a)" below.
  • the acrylic rubber-like polymer (a) is a crosslinked polymer having, as a main component, a structural unit derived from an acrylic ester.
  • "having as a main component” means that the content of structural units derived from acrylic ester is within the range described below.
  • the acrylic rubber-like polymer (a) is preferably a crosslinked polymer having structural units derived from an acrylic acid ester, structural units derived from other monomers copolymerizable therewith, and structural units derived from a polyfunctional monomer having two or more radically polymerizable groups (non-conjugated reactive double bonds) in one molecule.
  • the acrylic acid ester is preferably an alkyl acrylate having an alkyl group having 1 to 12 carbon atoms, such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), n-propyl acrylate (n-propyl acrylate), n-butyl acrylate (n-butyl acrylate), sec-butyl acrylate (sec-butyl acrylate), isobutyl acrylate (isobutyl acrylate), benzyl acrylate (benzyl acrylate), cyclohexyl acrylate (cyclohexyl acrylate), 2-ethylhexyl acrylate (2-ethylhexyl acrylate), or n-octyl acrylate (n-octyl acrylate). These may be used alone or in combination of two or more.
  • the content of structural units derived from acrylic esters is preferably within the range of 40 to 90 mass % of all structural units constituting the acrylic rubber-like polymer (a), and more preferably within the range of 50 to 80 mass %. By being within the above range, sufficient toughness can be imparted to the optical film.
  • Examples of other monomers copolymerizable with acrylic acid esters include methacrylic acid esters such as methyl methacrylate, styrenes such as styrene and methylstyrene, (meth)acrylonitriles, (meth)acrylamides, and (meth)acrylic acid.
  • methacrylic acid esters such as methyl methacrylate
  • styrenes such as styrene and methylstyrene
  • (meth)acrylonitriles such as methyl)acrylamides
  • (meth)acrylic acid examples include methacrylic acid esters such as methyl methacrylate, styrenes such as styrene and methylstyrene, (meth)acrylonitriles, (meth)acrylamides, and (meth)acrylic acid.
  • styrenes are preferred. These may be used alone or in combination of two or more.
  • the content of structural units derived from other monomers copolymerizable with acrylic esters is preferably within the range of 5 to 55% by mass, and more preferably within the range of 10 to 45% by mass, based on the total structural units constituting the acrylic rubber-like polymer (a).
  • polyfunctional monomers having two or more radically polymerizable groups in one molecule include allyl (meth)acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinyl benzene, ethylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipropylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate.
  • the content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.05 to 10 mass % of all structural units constituting the acrylic rubber-like polymer (a), and more preferably within the range of 0.1 to 5 mass %.
  • a content of 0.05 mass % or more it is easy to increase the degree of crosslinking of the obtained acrylic rubber-like polymer (a), and the hardness and rigidity of the optical film are less likely to be impaired.
  • the toughness of the optical film is less likely to be impaired.
  • composition of the monomers constituting the acrylic rubber-like polymer (a) can be measured, for example, by the peak area ratio detected by pyrolysis GC-MS.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is preferably 0°C or lower, and more preferably -10°C or lower. A glass transition temperature of 0°C or lower can impart appropriate toughness to the optical film.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be measured by the same method as described above.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be adjusted by the composition of the acrylic rubber-like polymer (a). For example, in order to lower the glass transition temperature (Tg), it is preferable to adjust the mass ratio of the acrylic ester having an alkyl group with 4 or more carbon atoms to the other monomer copolymerizable with the acrylic ester.
  • the mass ratio is expressed as the mass of the acrylic ester/the mass of the other monomer copolymerizable with the acrylic ester.
  • the mass ratio is preferably 3 or more, and is preferably within the range of 4 to 10.
  • the particles containing the acrylic rubber-like polymer (a) may be particles consisting of only the acrylic rubber-like polymer (a). They may also be particles having a hard layer consisting of a hard crosslinked polymer (c) having a glass transition temperature (Tg) of 20°C or higher, and a soft layer consisting of the acrylic rubber-like polymer (a) arranged around it. In addition, they may be particles consisting of an acrylic graft copolymer obtained by polymerizing a mixture of monomers such as methacrylic acid esters in at least one stage in the presence of the acrylic rubber-like polymer (a). The particles consisting of the acrylic graft copolymer may be core-shell type particles having a core containing the acrylic rubber-like polymer (a) and a shell covering the core.
  • the core contains an acrylic rubber-like polymer (a) and may further contain a hard crosslinked polymer (c) as necessary. That is, the core may have a soft layer made of the acrylic rubber-like polymer (a) and a hard layer made of the hard crosslinked polymer (c) disposed inside the soft layer.
  • the rigid crosslinked polymer will be referred to as "crosslinked polymer (c)" hereinafter.
  • the crosslinked polymer (c) is a crosslinked polymer containing a methacrylic acid ester as a main component.
  • the crosslinked polymer (c) is preferably a crosslinked polymer having a structural unit derived from a methacrylic acid ester, a structural unit derived from another monomer copolymerizable therewith, and a structural unit derived from a polyfunctional monomer having two or more radically polymerizable groups in one molecule.
  • the methacrylic acid ester is preferably an alkyl methacrylate ester, such as the above-mentioned alkyl acrylate ester in which the alkyl acid is replaced with methacrylic acid.
  • alkyl methacrylate ester examples include the same monomers as those described above as the other monomers copolymerizable with the acrylic acid ester.
  • polyfunctional monomer having two or more radically polymerizable groups in one molecule include the same as those mentioned above.
  • the content of structural units derived from methacrylic acid alkyl esters is preferably within the range of 40 to 100% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the content of structural units derived from other monomers copolymerizable with methacrylic acid esters is preferably within the range of 60 to 0% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.01 to 10% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the shell portion preferably contains a methacrylic polymer (b) (another polymer) having as its main component a structural unit derived from a methacrylic acid ester, graft-bonded to the acrylic rubber-like polymer (a).
  • a methacrylic polymer having a structural unit derived from a methacrylic acid ester as a main component will be referred to as a "methacrylic polymer (b)" hereinafter.
  • “having as a main component” means that the content of the structural unit derived from the methacrylic acid ester is within the range described below.
  • the methacrylic acid ester constituting the methacrylic polymer (b) is preferably a methacrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms, such as methyl methacrylate. These may be used alone or in combination of two or more.
  • the content of the methacrylic acid ester is preferably 50% by mass or more relative to all structural units constituting the methacrylic polymer (b).
  • the content of the methacrylic acid ester is more preferably 70% by mass or more relative to all structural units constituting the methacrylic polymer (b).
  • the methacrylic polymer (b) may further have a structural unit derived from another monomer copolymerizable with the methacrylic acid ester.
  • the other copolymerizable monomer include acrylic acid esters such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), and n-butyl acrylate (n-butyl acrylate); and (meth)acrylic monomers having an alicyclic, heterocyclic or aromatic ring (ring-containing (meth)acrylic monomers) such as benzyl (meth)acrylate (benzyl (meth)acrylate), dicyclopentanyl (meth)acrylate (dicyclopentanyl (meth)acrylate), and phenoxyethyl (meth)acrylate (phenoxyethyl (meth)acrylate).
  • the content of structural units derived from other copolymerizable monomers is preferably 50% by mass or less, and more preferably 30% by mass or less, based on the total structural units constituting the methacrylic polymer (b).
  • the ratio of the graft component in the rubber particles is preferably in the range of 10 to 250% by mass, and more preferably in the range of 15 to 150% by mass.
  • a graft ratio of 10% by mass or more means that the ratio of the graft component, i.e., the methacrylic polymer (b) whose main component is a structural unit derived from a methacrylic acid ester, is appropriately high. This makes it easier to increase the compatibility between the rubber particles and the methacrylic resin, making the rubber particles even less likely to aggregate. In addition, the rigidity of the optical film is less likely to be impaired.
  • the ratio of the acrylic rubber-like polymer (a) is not too low, so that the toughness of the optical film is less likely to be impaired.
  • the brittleness of the optical film can be sufficiently improved.
  • the graft rate can be measured using the following method.
  • the shape of the rubber particles is not particularly limited, but it is preferable that the rubber particles have a shape close to a perfect sphere.
  • the term "nearly spherical” refers to a shape in which the aspect ratio of the rubber particles is within the range of 1 to 2 when the cross section or surface of the optical film is observed.
  • the laminate is sufficiently resistant to deformation caused by contact with the rolls during transportation and deformation caused by internal stress during winding.
  • the average particle size of the rubber particles is preferably within the range of 100 to 400 nm. Having a particle size of 100 nm or more provides the optical film with sufficient toughness and stress relaxation properties. Furthermore, having a particle size of 400 nm or less ensures that the transparency of the optical film is not easily impaired. From the above viewpoints, it is more preferable that the average particle size of the rubber particles is within the range of 150 to 300 nm.
  • the average particle size of rubber particles can be calculated using the following method.
  • the average particle size of rubber particles can be measured as the average of the circle-equivalent diameters of 100 particles obtained by photographing the surface or slices of the laminate with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).
  • the circle-equivalent diameter can be calculated by converting the projected area of the particle obtained by photographing into the diameter of a circle with the same area. In this case, rubber particles observed by SEM or TEM observation at a magnification of 5000 times are used to calculate the average particle size.
  • the optical film according to the present invention can adjust the light transmittance by containing a colorant.
  • the colorant may be used alone or in combination of two or more kinds. From the viewpoint of the balance between brightness and color gamut, the content of the colorant is preferably within the range of 0.05 to 1.02% by mass based on the total mass of the resin for optical films.
  • At least one of them has a maximum absorption wavelength in the wavelength region of 570 to 610 nm. This makes it possible to reduce the average light transmittance of the optical film in the wavelength region of 570 to 610 nm, and to prevent the color gamut of the display device from narrowing.
  • the absorption maximum wavelength in the wavelength region of 570 to 610 nm is the maximum absorption maximum wavelength of the colorant.
  • maximum absorption maximum wavelength refers to the absorption maximum wavelength when there is only one absorption maximum wavelength, and to the absorption maximum wavelength that shows the maximum absorbance when there are multiple absorption maximum wavelengths.
  • the content of the colorant having a maximum absorption wavelength in the wavelength region of 570 to 610 nm is preferably within the range of 0.02 to 0.6 mass %, and more preferably within the range of 0.05 to 0.3 mass %, relative to the total mass of the resin for optical films.
  • the absorption maximum wavelength in the wavelength region of 420 to 460 nm is the longest absorption maximum wavelength of the colorant.
  • the content of the colorant having a maximum absorption wavelength in the wavelength region of 420 to 460 nm is preferably within the range of 0.005 to 0.3 mass %, and more preferably within the range of 0.01 to 0.3 mass %, relative to the total mass of the resin for optical films.
  • the above absorption maximum wavelength can be determined by dispersing the colorant in dichloromethane and measuring the absorption spectrum using an ultraviolet-visible spectrophotometer (e.g., "UV-2450" (manufactured by Shimadzu Corporation)).
  • an ultraviolet-visible spectrophotometer e.g., "UV-2450” (manufactured by Shimadzu Corporation)
  • the coloring agent may be a commercially available product or a synthetic product.
  • commercially available products include, but are not limited to, "#950” (manufactured by Mitsubishi Chemical Corporation), “FDR series”, “FDG series”, and “FDB series” (all manufactured by Yamada Chemical Industry Co., Ltd.), “Kayaset Black A-N” (manufactured by Nippon Kayaku Co., Ltd.), “NUBIAN (registered trademark) BLACK PC-5857” (manufactured by Orient Chemical Industry Co., Ltd.), and “Plast Black 8950-N” (manufactured by Arimoto Chemical Industry Co., Ltd.).
  • the coloring agent is not particularly limited, but examples include dyes and pigments.
  • the dyes are not particularly limited, and examples thereof include the following. However, from the viewpoint of absorbing light of a wide wavelength range, it is preferable to use at least two or more of the following dyes in combination. Also, a commercially available product in which two or more dyes are mixed in combination may be used.
  • Magenta dyes include “MS Magenta VP”, “MS Magenta HM-1450", “MS Magenta HSo-147” (all manufactured by Mitsui Toatsu Co., Ltd.), “AIZENSOT Red-1”, “AIZENSOT Red-2”, “AIZENSOT Red-3”, “AIZENSOT Pink-1”, “SPIRON Red GEH SPECIAL” (all manufactured by Hodogaya Chemical Co., Ltd.), “RESOLIN Red FB 200%”, “MACROLEX (registered trademark) Re d Violet R, MACROLEX (registered trademark) ROT5B (all manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red 802 (all manufactured by Nippon Kayaku), PHLOXIN, ROSE BENGAL, ACID Red (all manufactured by Daiwa Kasei), HSR-31, DIARESIN (registered trademark) Red K (all manufactured by Mitsubishi Kasei), and Oil Red (manufactured
  • Cyan dyes include "MS Cyan HM-1238", “MS Cyan HSo-16", “Cyan HSo-144", and “MS Cyan VPG” (all manufactured by Mitsui Toatsu Co., Ltd.), “AIZENSOT Blue-4" (manufactured by Hodogaya Chemical Co., Ltd.), “RESOLIN BR.Blue BGLN 200%, “MACROLEX (registered trademark) Blue RR”, “CERES (registered trademark) Blue GN”, “SIRIUS (registered trademark) SUPRATURQ.Blue Z-BGL”, and “SIRIUS (registered trademark) SUPRATURQ.Blue FB-LL 330%” (all manufactured by Bayer Japan Ltd.).
  • Examples include “KAYASET Blue FR”, “KAYASET Blue N”, “KAYASET Blue 814”, “Turq. Blue GL-5200", “Light Blue BGL-5200” (all manufactured by Nippon Kayaku Co., Ltd.), “DAIWA Blue 7000", “Oleosol (registered trademark) Fast Blue GL” (all manufactured by Daiwa Kasei Co., Ltd.), “DIARESIN (registered trademark) Blue P” (manufactured by Mitsubishi Kasei Corporation), “SUDAN Blue 670", “NEOPEN Blue 808", and “ZAPON Blue 806” (all manufactured by BASF Japan Ltd.).
  • Yellow dyes include "MS Yellow HSm-41", “Yellow KX-7", and “Yellow EX-27” (all manufactured by Mitsui Toatsu Co., Ltd.), “AIZENSOT Yellow-1", “AIZENSOT Yellow W-3", and “AIZENSOT Yellow-6” (all manufactured by Hodogaya Chemical Co., Ltd.), “MACROLEX (registered trademark) Yellow 6G”, and “MACROLEX (registered trademark) FLUOR.Yellow 10GN” (all manufactured by Bayer).
  • pigments are not particularly limited, and examples thereof include organic pigments, inorganic pigments, minerals, etc., having the following numbers as described in the Color Index. However, from the viewpoint of absorbing light of a wide wavelength range, it is preferable to use at least two or more of the following pigments in combination. Also, a commercially available product in which two or more of the following pigments are mixed in combination may be used.
  • Black pigments are not particularly limited, and examples thereof include carbon black, magnetic materials, iron-titanium composite oxide black, etc.
  • Carbon black is not particularly limited, and examples thereof include channel black, furnace black, acetylene black, thermal black, lamp black, etc.
  • Magnetic materials are not particularly limited, and examples thereof include ferrite, magnetite, etc.
  • the red or magenta pigment is not particularly limited, and examples thereof include C.I. Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 1 69, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, Ruby (chromium-containing corundum), Garnet, Spinel, etc.
  • the blue or cyan pigment is not particularly limited, and examples thereof include C.I. Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, 60, and Blue Sapphire (iron- and titanium-containing corundum).
  • the green pigment is not particularly limited, and examples thereof include C.I. Pigment Green 7, 26, 36, 50, and the like.
  • the yellow pigment is not particularly limited, and examples thereof include C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and yellow sapphire (nickel-containing corundum).
  • the average secondary particle diameter of the pigment is not particularly limited, but is preferably 0.1 ⁇ m or more, and more preferably 0.2 ⁇ m or more. By keeping it within the above range, the sliding properties of the pigment particles are improved and they are less likely to aggregate, which further reduces unevenness in the light transmittance within the optical film.
  • the average secondary particle diameter of the pigment is not particularly limited, but is preferably 3 ⁇ m or less, and more preferably 2.6 ⁇ m or less. By keeping it within the above range, dispersion spots in the optical film are less likely to occur, unevenness in the light transmittance in the optical film is further reduced, and the haze value is also reduced.
  • the average secondary particle diameter of a pigment can be determined by directly measuring the size of the secondary particles from an electron microscope photograph of an optical film. Specifically, a transmission electron microscope (TEM) "H-7650" (Hitachi High-Tech Corporation) is used to measure particle images, and the average equivalent diameter of a circle with an equal area of 100 randomly selected secondary particles is calculated, and this value is taken as the average secondary particle diameter.
  • TEM transmission electron microscope
  • the optical film further contains fine particles.
  • inorganic compound particles examples include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate.
  • Examples of fine particles of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resins, silicone resins, polycarbonate, benzoguanamine resins, melamine resins, polyolefin powders, polyester, polyamide, polyimide, polyethylene fluoride resins, etc.
  • Other examples include crushed fractions of organic polymer compounds such as starch, and polymer compounds synthesized by suspension polymerization.
  • the fine particles preferably contain silicon, and more preferably silicon dioxide, from the viewpoint of reducing turbidity.
  • Commercially available products of such fine particles include, for example, Aerosil (registered trademark, the same applies below) R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.).
  • the content of the fine particles is preferably within the range of 0.05 to 10% by mass relative to the total mass of the optical film.
  • the method for producing the optical film is not particularly limited, but from the viewpoint of obtaining a desired optical film, it is preferable to produce the optical film by a solution casting method.
  • the optical film A and the optical film B may or may not be produced by the same method.
  • a dope containing a resin, a solvent, and any other ingredients is prepared, and then the dope is applied to a substrate and then dried to obtain an optical film.
  • the solvent used for the dope is not particularly limited as long as it can disperse the resin and, if necessary, rubber particles, colorant, etc. well.
  • the solvent include alcohols such as methanol, ethanol, propanol, n-butanol, 2-butanol, tert-butanol, cyclohexanol, etc.; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone, acetone, etc.; esters such as ethyl acetate, methyl acetate, ethyl lactate, isopropyl acetate, amyl acetate, ethyl butyrate, etc.; ethers such as tetrahydrofuran (THF), 1,4-dioxane, etc.; glycol ethers; and hydrocarbons such as toluene, benzene,
  • glycol ethers examples include propylene glycol mono (C1-C4) alkyl ethers and propylene glycol mono (C1-C4) alkyl ether esters.
  • propylene glycol mono(C1-C4) alkyl ethers include propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, and propylene glycol monobutyl ether.
  • propylene glycol mono (C1-C4) alkyl ether esters include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and the like. These may be used alone or in combination of two or more.
  • methyl ethyl ketone, ethyl acetate, acetone, or tetrahydrofuran is preferred from the viewpoints of ease of dissolving the resin material, low boiling point, and ease of increasing the drying speed and productivity.
  • solvents may be further mixed with a solvent such as dichloromethane.
  • the solids concentration of the dope is preferably within the range of, for example, 5 to 20% by mass in order to make it easier to adjust the viscosity.
  • the dope may further contain other components in addition to those described above, if necessary.
  • the other components include a matting agent (fine particles), an ultraviolet absorbing agent, a surfactant, and the like.
  • matting agent can impart slipperiness to the optical film.
  • matting agents include inorganic fine particles such as silica particles, and organic fine particles with a glass transition temperature of 80°C or higher.
  • ultraviolet absorbers examples include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.
  • Surfactants include, for example, anionic surfactants such as carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type; cationic surfactants such as alkylamine salt type and quaternary ammonium salt type; and amphoteric surfactants such as carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type. Any type can be used.
  • anionic surfactants such as carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type
  • cationic surfactants such as alkylamine salt type and quaternary ammonium salt type
  • amphoteric surfactants such as carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type. Any type can be used.
  • the order in which the components contained in the dope are mixed is not particularly limited.
  • the method for mixing the components is also not particularly limited, and they may be mixed using, for example, a stirrer.
  • the mixing time is not particularly limited, but is preferably within the range of 1 to 10 hours.
  • the mixing temperature is also not particularly limited, but is preferably within the range of 20 to 50°C.
  • the viscosity of the dope at 25°C is not particularly limited as long as it is sufficient to produce an optical film of the desired thickness, but it is preferably within the range of 5 to 5000 mPa ⁇ s.
  • the viscosity of the dope is 5 mPa ⁇ s or more, it is easy to produce an optical film of the desired thickness.
  • the viscosity is 5000 mPa ⁇ s or less, it is possible to suppress unevenness in thickness caused by an increase in the viscosity of the solution. From the same viewpoint, it is more preferable that the viscosity of the dope is within the range of 100 to 1000 mPa ⁇ s.
  • the viscosity of the dope at 25°C can be measured with an E-type viscometer.
  • the obtained dope may be filtered if necessary.
  • the optical film according to the present invention can be produced by applying the obtained dope to the surface of a substrate, and then drying the dope to remove the solvent from the dope. At this time, a laminated film including the substrate and the optical film is produced.
  • the step of applying the dope to the substrate and the step of forming the optical film (drying step) will be described below.
  • Step of applying dope the dope obtained above is applied to the surface of the substrate. Specifically, the dope is coated on the surface of the substrate.
  • the substrate is not particularly limited as long as it can support the optical film, but it is usually preferable for it to be a resin film.
  • polyester resin films e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.
  • cycloolefin resin films COP
  • acrylic films e.g., acrylic films
  • cellulose resin films e.g., cellulose triacetate film (TAC)
  • TAC cellulose triacetate film
  • a PET film, a cellulose triacetate film (TAC) or a cycloolefin resin film is preferred.
  • the resin film for the substrate may be one that has been heat-relaxed or stretched.
  • the heat-relaxing temperature is not particularly limited, but is preferably within the range of (Tg+60) to (Tg+180)°C, where Tg is the glass transition temperature of the resin that constitutes the substrate resin film. Heat-relaxing may be performed before or after the release layer is produced.
  • the stretching treatment can increase the orientation of the resin molecules by stretching the substrate resin film, and can increase the tensile modulus of the substrate resin film.
  • the stretching treatment may be performed, for example, in the uniaxial direction of the substrate resin film or in the biaxial direction.
  • the stretching treatment may be performed under any conditions, and is preferably performed, for example, in a range of a stretch ratio of 120 to 900%.
  • the stretch ratio here is a value obtained by multiplying the stretch ratios in each direction. Whether or not the substrate resin film is stretched (whether or not it is a stretched film) can be confirmed, for example, by whether or not it has an in-plane slow axis (an axis extending in the direction in which the refractive index is maximum).
  • the substrate resin film preferably further has a release layer on its surface.
  • the presence of the release layer makes it easier to peel the optical film from the substrate resin film.
  • the release layer is not particularly limited as long as it contains a known release agent or a release agent.
  • the release agent contained in the release layer may be a silicone-based release agent or a non-silicone-based release agent.
  • silicone-based release agent examples include known silicone-based resins.
  • non-silicone release agents include long-chain alkyl pendant polymers obtained by reacting polyvinyl alcohol or ethylene-vinyl alcohol copolymers with long-chain alkyl isocyanates, olefin resins (e.g., copolymerized polyethylene, cyclic polyolefins, polymethylpentene, etc.), polyarylate resins (e.g., polycondensates of aromatic dicarboxylic acid components and dihydric phenol components, etc.), and fluororesins (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), copolymers of tetrafluoroethylene and perfluoroalkoxyethylene (PFA), copolymers of tetrafluoroethylene and hexafluoropropylene (FEP), copolymers of te
  • the release layer may further contain additives as necessary.
  • additives include fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity adjusters, thickeners, defoamers, ultraviolet absorbers, etc.
  • the thickness of the release layer is not particularly limited as long as it provides the desired releasability, but it is preferably within the range of 0.1 to 1.0 ⁇ m.
  • the thickness of the substrate is not particularly limited, but is preferably within the range of 10 to 100 ⁇ m, and more preferably within the range of 25 to 50 ⁇ m.
  • the method for applying the dope is not particularly limited, and examples thereof include known methods such as back coating, gravure coating, spin coating, wire bar coating, and roll coating. Among these, the back coating method is preferred from the viewpoint of forming a coating film that is thin and has a uniform thickness.
  • the dope applied to the substrate is dried. Drying methods include, for example, blowing air or heating. Among these, drying by blowing air is preferred from the viewpoint of easily suppressing curling of the laminated film.
  • the drying conditions e.g., drying temperature, solvent concentration in the atmosphere, drying time, etc.
  • the amount of residual solvent in the coating film after drying i.e., the optical film
  • the distribution state of the rubber particles in the optical film can be adjusted by adjusting the drying conditions. Specifically, from the viewpoint of making it easier to unevenly distribute the rubber particles, it is preferable to use a solvent that has good affinity with the rubber particles, to set the drying temperature high, and to set the solvent concentration in the atmosphere low.
  • the drying temperature is preferably within the range of (Tb-50) to (Tb+50)°C, and more preferably within the range of (Tb-40) to (Tb+40)°C, where Tb is the boiling point of the solvent (°C).
  • Tb is the boiling point of the solvent (°C).
  • the drying temperature is preferably 40°C or higher.
  • the solvent concentration in the atmosphere during drying is preferably in the range of 0.10 to 0.30 mass%, and more preferably 0.10 to 0.20 mass%. By making it 0.10 mass% or more, excessive evaporation of the solvent can be prevented, making it less likely for the coating film to crack. Furthermore, by making it 0.30 mass% or less, the evaporation rate of the solvent from the coating film can be increased appropriately, making it easier for the rubber particles to be unevenly distributed on the surface.
  • the solvent concentration in the atmosphere can be adjusted by the drying temperature and the dew point temperature inside the drying oven. Furthermore, the solvent concentration in the atmosphere can be measured with an infrared gas concentration meter.
  • the optical film according to the present invention is obtained by peeling off the substrate from the laminate film of the substrate and optical film thus obtained.
  • T A and T B satisfy the following formula (1) and both T A and T B are within the range of 39 to 89%.
  • the average light transmittance in the wavelength region of 380 to 780 nm can be measured by the following method. Each optical film is conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, a total light transmittance of each wavelength in the wavelength region of 380 to 780 nm is measured using a UV-visible spectrophotometer (for example, “UV-2450” (manufactured by Shimadzu Corporation)), and the arithmetic average value is calculated.
  • a UV-visible spectrophotometer for example, “UV-2450” (manufactured by Shimadzu Corporation)
  • optical film A When the laminate of the present invention is attached to a display device so that optical film A is positioned closer to the viewing side than optical film B, pen input to the display device is performed from the optical film A side.
  • optical film B suppresses the outward tensile stress acting on the back surface of the thin glass (the back surface when the surface closer to the viewing side is considered the front surface), thereby preventing the thin glass from bending and breaking (impact resistance).
  • the storage modulus of the optical film A at 25° C. is preferably 2.0 GPa or more.
  • the storage modulus of the optical film B at 25° C. is preferably within a range of 0.1 to 3.5 GPa, and more preferably within a range of 1.0 to 3.5 GPa, from the viewpoints of impact resistance and contrast after bending.
  • the loss tangent (tan ⁇ B ) of the optical film B at 25° C. is preferably within a range of 0.01 to 0.3, and more preferably within a range of 0.05 to 0.3.
  • the storage modulus and loss tangent of the optical film at 25°C can be adjusted by appropriately selecting the type and content of materials (resin, rubber particles, etc.).
  • the storage modulus and loss tangent at 25° C. of the optical film can be measured using a rheometer device “RSA-3” (manufactured by TA Instruments Japan Co., Ltd.) under the following test conditions.
  • Test conditions dynamic viscoelasticity test
  • Testing machine Dynamic viscoelasticity measuring device "RSA-3” (manufactured by TA Instruments Japan, Inc.)
  • Deformation method tension Preload load: 55g Temperature range: -70 to 200°C Frequency: 1.0Hz Displacement: ⁇ 0.1% Sample: Width 5mm Chuck distance: 20 mm
  • the optical film preferably has an in-plane retardation (R 0 ) represented by the following formula in the range of ⁇ 10 to 10 nm.
  • R 0 (Nx - Ny) x d
  • Nx is the maximum refractive index in the plane of the optical film
  • Ny is the minimum refractive index in the plane of the optical film
  • d is the thickness of the optical film.
  • the in-plane retardation (R 0 ) can be measured using an automatic birefringence meter, for example, an automatic birefringence meter "KOBRA (registered trademark)-21ADH” (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of a temperature of 23° C. and a humidity of 55% RH.
  • an automatic birefringence meter "KOBRA (registered trademark)-21ADH” (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of a temperature of 23° C. and a humidity of 55% RH.
  • the thickness of the optical film is preferably within the range of 10 to 60 ⁇ m, more preferably within the range of 15 to 50 ⁇ m, and even more preferably within the range of 20 to 40 ⁇ m.
  • the glass transition temperature of the optical film is preferably within the range of -30 to 180°C. If multiple glass transition temperatures are observed when measuring the glass transition temperature of the optical film, the lowest glass transition temperature observed shall be regarded as the glass transition temperature of the optical film.
  • the glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.
  • the glass layer according to the present invention is preferably a thin film glass from the viewpoint of excellent durability, flatness, etc.
  • materials for thin film glass include lithium aluminosilicate glass, soda-lime glass, borosilicate glass, silica glass, alkali metal aluminosilicate glass, and aluminosilicate glass with a low alkali content.
  • the thin film glass is preferably an alkali-free glass that contains substantially no alkali components.
  • the content of alkali components is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less, relative to the total mass of the thin film glass.
  • the thickness of the thin film glass is preferably within a range of 10 to 50 ⁇ m.
  • the thickness of the thin film glass 10 ⁇ m or more, sufficient impact resistance of the laminate can be obtained.
  • the thickness of the thin film glass 50 ⁇ m or less sufficient flexibility of the laminate can be obtained.
  • the thinner the thin film glass is, the thinner the laminate can be, and the thinner the display device can be. From the viewpoint of achieving both impact resistance and contrast after bending, the thickness of the thin glass is more preferably within the range of 10 to 40 ⁇ m, and further preferably within the range of 10 to 30 ⁇ m.
  • Thin glass can be produced by a commonly known method, such as a float method, a down-draw method, an overflow down-draw method, etc.
  • the overflow down-draw method or the float method is preferred because the surface of the thin glass does not come into contact with the forming member during production, and the surface of the obtained thin glass is less likely to be scratched.
  • the float method is preferred from the viewpoint of obtaining a thin glass having a thickness in the range of 10 to 50 ⁇ m.
  • the thinner the glass the weaker it is and the more susceptible it is to breakage, making it difficult to handle and process thin-film glass on its own.
  • a thicker support substrate hereafter also referred to as a "carrier substrate”
  • peeling off the support substrate as a post-processing step
  • FIG. 4 is a schematic diagram showing an example of a method for producing thin-film glass.
  • Step 1 in step 1, a thin film glass 22 is prepared so that a first surface of the thin film glass is in contact with a carrier substrate 21 having a bonding surface. Then, a contact film 23 (also called a "contact film”) having adhesive force is pressure-bonded to a second surface opposite to the first surface.
  • the thin-film glass material is poured to the desired thickness onto a carrier substrate 21 that has sufficient strength and a thickness that is easy to process. This creates a first surface of the thin-film glass 22 that is in contact with the carrier substrate 21. After that, a contact film 23 is pressed onto a second surface on the opposite side to the first surface.
  • Step 2 As shown in FIG. 4, in step 2, the thin glass 22 is peeled off from the carrier substrate 21 by the contact film 23 having high adhesive strength.
  • Step 3 in step 3, a weakening treatment (electromagnetic radiation irradiation 24) is performed to weaken the adhesive strength of the contact film, thereby removing the contact film 23 from the second surface of the thin glass 22.
  • a weakening treatment electromagnettic radiation irradiation 24
  • the contact film 23 is used to safely hold the thin-film glass 22, thereby protecting the thin-film glass 22.
  • the exposed surface of the thin-film glass 22 can be protected from, for example, mechanical damage, and can be handled safely and easily.
  • Examples of materials for the contact film include polyolefins (PO) such as polyethylene terephthalate (PET) and polyethylene (PE).
  • PO polyolefins
  • PET polyethylene terephthalate
  • PE polyethylene
  • the contact film is usually adhered to the thin glass by an adhesive layer made of an adhesive provided on one side of the substrate.
  • the contact film may also be adhered directly to the thin glass by the adhesive properties of the contact film itself.
  • the adhesive strength between the contact film and the second surface of the thin film glass is appropriately selected so that the peeling device transmits sufficient force to peel the thin film glass from the carrier substrate.
  • the contact film is preferably in the form of a foil or tape. By forming it into a foil or tape, it can be wound into a roll.
  • the thickness of the contact film is preferably 50 ⁇ m or more, more preferably 80 ⁇ m or more, more preferably 125 ⁇ m or more, and particularly preferably 150 ⁇ m or more.
  • the thin glass is preferably fabricated on a carrier substrate by the aforementioned downdraw method, overflow downdraw method, or float method.
  • the thickness of the carrier substrate is preferably 100 ⁇ m or more, more preferably 300 ⁇ m or more, and even more preferably 500 ⁇ m or more. Furthermore, the width of the carrier substrate is preferably 3 inches or more (1 inch is 2.54 cm), more preferably 6 inches or more, even more preferably 8 inches or more, and particularly preferably 12 inches or more.
  • the carrier substrate is preferably equal to or larger than the first generation glass substrate size, for example, second to eighth generation sizes. Alternatively, it may be even larger, for example, 1x1m to 3x3m.
  • the carrier substrate may be of various shapes, such as rectangular, elliptical, circular, etc.
  • the thin glass film, together with the contact film, is peeled off from the carrier substrate by the adhesive force of the contact film.
  • the contact film is then peeled off, leaving a single thin glass film.
  • the adhesive strength of the contact film Before peeling the contact film from the thin glass, it is preferable to weaken the adhesive strength of the contact film by subjecting it to a treatment to weaken its adhesive strength. Specifically, it is preferable to reduce the adhesive strength to 0.5 N/25 mm or less.
  • electromagnetic radiation such as infrared, ultraviolet, or visible light
  • the electromagnetic radiation may be narrowband or may cover a wider band depending on the adhesive material used. It may also be laser radiation.
  • Some commercially available adhesive materials can be at least partially deactivated by exposure to electromagnetic radiation and can be used as contact films.
  • heat treatment may be used as a weakening treatment.
  • the electromagnetic radiation is preferably applied from the outer surface of the contact film, i.e., the side to which the thin glass is not adhered.
  • An example of a contact film is "NDS4150-20" (manufactured by Dao Ming Optical Co., Ltd.).
  • a corresponding weakening treatment is exposure to ultraviolet light with a wavelength of 365 nm.
  • the thin film glass for example, commercially available products manufactured by SCHOTT Co., Ltd., Nippon Electric Glass Co., Ltd., etc. can be used.
  • Adhesive layer refers to a layer having sufficient adhesiveness to attach the cover unit to the display unit or to bond each layer in the laminate. It is also a general term for adhesive layer C and adhesive layer D. The materials constituting the adhesive layer C and the adhesive layer D may or may not be the same.
  • the adhesive layer is preferably made of an adhesive. The adhesive that is preferably used will be described below.
  • the adhesive layer according to the present invention may be in the form of a film that can be rolled up, or in the form of a coating layer.
  • the coating layer is formed by applying an adhesive onto an adjacent layer and then curing the applied adhesive.
  • the adhesive is not particularly limited, and examples thereof include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.
  • acrylic-based adhesives are preferred.
  • Acrylic-based adhesives are excellent in transparency and adhesive properties (adhesion, cohesion, and adhesion). They are also excellent in weather resistance, heat resistance, and the like.
  • the term "acrylic pressure-sensitive adhesive” refers to a pressure-sensitive adhesive that contains an acrylic polymer as a base polymer.
  • Adhesive layer C The laminate of the present invention preferably further comprises an adhesive layer C.
  • the layers are preferably arranged in the order of the optical film A, the glass layer, the optical film B, and the adhesive layer C, as shown in FIG.
  • T B and T C when the average light transmittances in the wavelength region of 380 to 780 nm of the optical film B and the adhesive layer C are T B and T C , respectively, it is preferable that T B and T C satisfy the following formula (2). Equation (2): TB ⁇ TC
  • the laminate By further providing an adhesive layer C on the side of the laminate closest to the display device, the laminate can be attached to the display device.
  • optical film B can suppress the outward tensile stress acting on the back surface of the thin film glass (the back surface when the surface closer to the viewing side is considered the front surface), it is possible to prevent the thin film glass from bending and breaking (impact resistance).
  • adhesive layer C adjacent to optical film B, the outward tensile stress acting on the back surface of the thin film glass can be further suppressed.
  • the adhesive layer C can also contain a colorant to adjust the light transmittance.
  • a colorant can reduce the adhesive strength.
  • Adhesive layer D The laminate of the present invention preferably further comprises an adhesive layer D.
  • the layers are preferably arranged in the order of the optical film A, the glass layer, the adhesive layer D, and the optical film B.
  • the layers are preferably arranged in the order of the optical film A, the glass layer, the adhesive layer D, the optical film B, and the adhesive layer C, as shown in FIG.
  • the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
  • the pen input is performed from the optical film A side.
  • the outward tensile stress acting on the back surface of the thin film glass (the back surface when the surface closer to the viewing side is considered the front surface) can be suppressed, it is possible to prevent the thin film glass from bending and breaking (impact resistance).
  • the outward tensile stress acting on the back surface of the thin film glass can be further suppressed.
  • the adhesive layer made of an acrylic adhesive is preferably a layer formed by, for example, ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive. Note that, by ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive, a (meth)acrylic polymer is generated.
  • the "ultraviolet-curable acrylic adhesive” preferably contains a monomer component containing alkyl (meth)acrylate or a partial polymer of the monomer component, a photopolymerization initiator, etc.
  • the adhesive layer By appropriately adjusting the light transmittance of the adhesive layer, the adhesive layer can also be given a part of the function of a polarizing plate, specifically, the reflection of external light can be further suppressed. Furthermore, when the laminate is used as a cover glass unit of a display device, sufficient contrast can be obtained.
  • the light transmittance can be adjusted by adding a colorant to the adhesive layer (ultraviolet-curable acrylic adhesive).
  • the colorant may be the same as that used in the optical film.
  • the content of the colorant is preferably 1.02 mass % or less based on the total mass of the adhesive layer.
  • the UV-curable acrylic pressure-sensitive adhesive has as its base polymer a (meth)acrylic polymer obtained by UV-curing (UV-polymerizing) a monomer component containing an acrylate or a partial polymer of the monomer component.
  • the alkyl (meth)acrylate contained in the monomer component and other monomers that may be contained will be described below.
  • the other monomers that may be contained are preferably monofunctional monomers, but may also be polyfunctional monomers.
  • alkyl (meth)acrylate refers to acrylic and methacrylic, and is a general term for both.
  • alkyl (meth)acrylate refers to alkyl acrylate and alkyl methacrylate, and is a general term for both.
  • the alkyl (meth)acrylate according to the present invention is preferably an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal. These may be used alone or in combination of two or more.
  • alkyl (meth)acrylates include alkyl (meth)acrylates having a branched alkyl group having 4 to 9 carbon atoms. Specific examples include n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and isononyl (meth)acrylate. These may be used alone or in combination of two or more.
  • the content of alkyl (meth)acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the monomer components.
  • Examples of monofunctional copolymerizable monomers (monofunctional monomers) other than alkyl (meth)acrylates include cyclic nitrogen-containing monomers.
  • the cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure.
  • the cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure.
  • Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl- ⁇ -caprolactam, and methylvinylpyrrolidone, and vinyl-based monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. Also included are (meth)acrylic monomers containing a heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among these, lactam vinyl monomers are preferred.
  • the content of the cyclic nitrogen-containing monomer is preferably 0.5 to 50 mass%, more preferably 0.5 to 40 mass%, and even more preferably 0.5 to 30 mass%, based on the total mass of the monomer components.
  • a monofunctional monomer is a hydroxyl group-containing monomer.
  • the hydroxyl group-containing monomer has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a hydroxyl group.
  • hydroxy group-containing monomer examples include hydroxyalkyl (meth)acrylates such as 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, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.
  • hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxy
  • hydroxyethyl (meth)acrylamide examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.
  • hydroxyalkyl (meth)acrylates are preferred. These may be used alone or in combination of two or more.
  • the content of the hydroxyl group-containing monomer is preferably within the range of 1 to 30% by mass, more preferably within the range of 2 to 27% by mass, and even more preferably within the range of 3 to 25% by mass, based on the total mass of the monomer components.
  • monofunctional monomers include carboxyl group-containing monomers and monomers having cyclic ether groups.
  • carboxyl group-containing monomer there are no particular limitations on the carboxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a carboxyl group.
  • carboxy group-containing monomer examples include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.
  • itaconic acid or maleic acid may be an anhydride thereof.
  • acrylic acid or methacrylic acid is preferred, and acrylic acid is more preferred. These may be used alone or in combination of two or more.
  • the monomer having a cyclic ether group is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a cyclic ether group, such as an epoxy group or an oxetane group.
  • Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc.
  • Examples of oxetane group-containing monomers include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.
  • the content of the carboxyl group-containing monomer or the monomer having a cyclic ether group is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, based on the total mass of the monomer components.
  • alkyl (meth)acrylates represented by CH 2 ⁇ C(R 1 )COOR 2 (R 1 represents a hydrogen atom or a methyl group, and R 2 represents a substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group).
  • alkyl (meth)acrylate represented by CH 2 ⁇ C(R 1 )COOR 2 examples include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.
  • the content of the alkyl (meth)acrylate represented by the above CH 2 ⁇ C(R 1 )COOR 2 is preferably 50 mass% or less, more preferably 45 mass% or less, and even more preferably 40 mass% or less, based on the total mass of the monomer components.
  • monofunctional monomers include, for example, vinyl acetate, vinyl propionate, styrene, ⁇ -methylstyrene; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Also included are monomers having a cyclic structure such as terpene (meth)acrylate and dicyclopentanyl (meth)acrylate.
  • silane-based monomers containing a silicon atom examples include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.
  • monomers may contain polyfunctional monomers as necessary in order to adjust the cohesive strength of the adhesive layer.
  • polyfunctional monomer there are no particular limitations on the polyfunctional monomer, so long as it is a monomer that has at least two polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl groups or vinyl groups.
  • polyfunctional monomers include ester compounds of polyhydric alcohols and (meth)acrylic acid such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane tri(
  • trimethylolpropane tri(meth)acrylate hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate is preferred. These may be used alone or in combination of two or more.
  • the content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, etc., but is preferably 3 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less, relative to the total mass of the monofunctional monomer.
  • the content of the polyfunctional monomer is preferably 0.001 mass% or more.
  • the monomer component may contain a partial polymer of the above monomer component.
  • the ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention preferably contains a photopolymerization initiator. By including a photopolymerization initiator, the monomer components can be polymerized sufficiently.
  • the photopolymerization initiator is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization, and any commonly used photopolymerization initiator can be suitably used. Examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, ⁇ -ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.
  • bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide examples include, for example, “Omnirad (registered trademark) 819" (manufactured by IGM Resins B.V.)), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) TPO H” (manufactured by IGM Resins B.V.)), and the like. These may be used alone or in combination of two or more.
  • the content of the photopolymerization initiator is preferably within the range of 0.005 to 0.5% by mass, and more preferably within the range of 0.02 to 0.1% by mass, based on the total mass of the monomer components. By being within the above range, ultraviolet curing (ultraviolet polymerization) can proceed sufficiently.
  • the ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention may further contain a silane coupling agent, a crosslinking agent, and the like.
  • Silane coupling agents include, for example, epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl- ⁇ -aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyan
  • the content of the silane coupling agent is preferably 1% by mass or less, more preferably in the range of 0.01 to 1% by mass, and even more preferably in the range of 0.02 to 0.6% by mass, based on the total mass of the monomer components.
  • crosslinking agent examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxides, etc.
  • isocyanate-based crosslinking agents are preferred. These may be used alone or in combination of two or more.
  • An isocyanate crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or by polymerization, etc.) in one molecule.
  • isocyanate crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.
  • the content of the crosslinking agent is preferably 5% by mass or less, more preferably in the range of 0.01 to 5% by mass, even more preferably in the range of 0.01 to 4% by mass, and particularly preferably in the range of 0.02 to 3% by mass, based on the total mass of the monomer components.
  • the UV-curable acrylic adhesive may contain other additives as appropriate depending on the application.
  • additives include tackifiers (e.g., rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc. that are solid, semi-solid, or liquid at room temperature); fillers such as hollow glass balloons; plasticizers; antioxidants; antioxidants, etc.
  • the viscosity of the UV-curable acrylic adhesive can be adjusted, for example, by adding various polymers such as thickening additives, polyfunctional monomers, etc., or by partially polymerizing the monomer components in the UV-curable acrylic adhesive.
  • the partial polymerization may be carried out before or after adding various polymers such as thickening additives, polyfunctional monomers, etc.
  • the viscosity of the ultraviolet-curable acrylic adhesive varies depending on the content of additives, etc. Therefore, the polymerization rate when the monomer components in the ultraviolet-curable acrylic adhesive are partially polymerized cannot be uniquely determined.
  • the polymerization rate is preferably 20% or less, more preferably within the range of 3 to 20%, and even more preferably within the range of 5 to 15%.
  • the viscosity can be adjusted to a level suitable for application work.
  • the adhesive layer can be produced by applying an ultraviolet-curable acrylic adhesive onto an adjacent layer, and irradiating it with ultraviolet light to cause ultraviolet curing (ultraviolet polymerization).
  • an ultraviolet-curable acrylic adhesive may be applied onto a substrate, and then ultraviolet light may be irradiated to cause ultraviolet curing (ultraviolet polymerization) to produce a film-like adhesive layer.
  • the substrate is not particularly limited, and examples include release films, transparent resin films, etc.
  • release films include release resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; and thin materials such as nets, foam sheets, metal foils, and laminates of these.
  • resin films are preferred from the viewpoint of excellent surface smoothness.
  • release resin films include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.
  • the thickness of the release film is preferably within the range of 5 to 200 ⁇ m, and more preferably within the range of 5 to 100 ⁇ m.
  • the release film is preferably subjected to a release treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent. It is also preferable to perform an anti-soiling treatment using silica powder or the like. In addition, anti-static treatments such as coating, kneading or deposition may be performed. In particular, release treatment using a silicone-based, fluorine-based or long-chain alkyl-based release agent makes it easier to peel off the film-like adhesive layer.
  • the transparent resin film is not particularly limited, but is preferably transparent and composed of a single layer film.
  • transparent resin films include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins.
  • polyester resins, polyimide resins, and polyethersulfone resins are preferred.
  • the thickness of the transparent resin film is preferably within the range of 2 to 200 ⁇ m, and more preferably within the range of 20 to 188 ⁇ m.
  • the method for applying the UV-curable acrylic adhesive is not particularly limited, and any conventionally known method can be used.
  • application methods 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 coater methods.
  • the illuminance of the ultraviolet light irradiated to the ultraviolet-curable acrylic adhesive is preferably within the range of 5 to 200 mW/ cm2 .
  • the polymerization reaction time can be shortened, resulting in excellent productivity.
  • the photopolymerization initiator can be prevented from being rapidly consumed.
  • the polymerization proceeds sufficiently, and a high molecular weight polymer ((meth)acrylic polymer) can be obtained. This allows the adhesive layer to have excellent holding power, especially at high temperatures.
  • the integrated amount of ultraviolet light is preferably within the range of 100 to 5000 mJ/ cm2 .
  • the ultraviolet lamp used in the present invention is not particularly limited, but is preferably an LED lamp.
  • the LED lamp emits less heat than other ultraviolet lamps, so that the temperature rise during the ultraviolet curing of the ultraviolet curing acrylic adhesive can be suppressed. This allows a polymer with a high molecular weight to be obtained, and an adhesive layer with sufficient cohesive strength can be obtained, thereby increasing the holding power at high temperatures when the adhesive sheet is made.
  • the ultraviolet lamp may be a combination of a plurality of ultraviolet lamps.
  • ultraviolet light may be intermittently irradiated, and a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated may be provided.
  • the final polymerization rate of the monomer components in the UV-curable acrylic adhesive is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.
  • the peak wavelength of the ultraviolet light irradiated onto the ultraviolet-curing acrylic adhesive is preferably within the range of 200 to 500 nm, and more preferably within the range of 300 to 450 nm.
  • the peak wavelength of the ultraviolet light is 500 nm or less, the photopolymerization initiator decomposes and the polymerization reaction begins.
  • the peak wavelength of the ultraviolet light is 200 nm or more, the scission of the polymer chain can be suppressed, and sufficient adhesion can be obtained.
  • Methods for blocking oxygen include creating a release film on the coating layer of the UV-curable acrylic adhesive, and carrying out the polymerization reaction in a nitrogen atmosphere.
  • release films include the release films mentioned above.
  • the storage modulus of the adhesive layer at 25° C. is preferably within the range of 0.5 to 10.0 MPa, and more preferably within the range of 1.2 to 8.0 MPa.
  • the storage modulus of adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
  • the storage modulus of the adhesive layer at 25°C can be adjusted by appropriately selecting the type and content of materials (monomer components, UV absorbers, photopolymerization initiators, etc.), UV irradiation conditions, etc.
  • the storage modulus of the adhesive layer at 25° C. can be measured using a viscoelasticity measuring device "ARES-G2" (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
  • Test conditions dynamic viscoelasticity test
  • Testing machine Viscoelasticity measuring device "ARES-G2” (manufactured by TA Instruments Japan, Inc.)
  • Deformation method Rotation Temperature range: -50 to 100°C Frequency: 1Hz
  • Displacement Strain 0.05%
  • Distance between chucks Automatically variable so that the load becomes 10 g (approximately equal to the sample thickness).
  • the thickness of the adhesive layer is preferably within the range of 2 to 60 ⁇ m, more preferably within the range of 2 to 20 ⁇ m, and even more preferably within the range of 5 to 15 ⁇ m, from the viewpoint of making the final laminate thinner.
  • the weight average molecular weight (Mw) of the resin material (e.g., (meth)acrylic polymer) used in the adhesive layer is preferably within the range of 100,000 to 5,000,000, and more preferably within the range of 200,000 to 1,000,000, from the viewpoint of controlling the storage modulus.
  • the weight average molecular weight (Mw) of the resin material used in the adhesive layer is preferably smaller than the weight average molecular weight (Mw) of the resin material used in the optical film. This allows the effects of the present invention to be obtained more efficiently.
  • the weight average molecular weight (Mw) of the resin material can be measured using a gel permeation chromatograph "HLC8220GPC” (manufactured by Tosoh Corporation) and columns “TSK-GEL G6000", “HXL-G5000”, “HXL-G5000”, “HXL-G4000”, and “HXL-G3000HXL” (all manufactured by Tosoh Corporation, in series). 20 mg ⁇ 0.5 mg of a sample is dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution is then injected into a column (temperature 40° C.) and measured with an RI detector at a temperature of 40° C., and the value is expressed in terms of styrene.
  • the glass transition temperature (Tg) of the adhesive layer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower, from the viewpoint of achieving both impact resistance in a low-temperature environment and contrast after bending.
  • the glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.
  • the manufacturing method of the laminate of the present invention is not particularly limited, and examples thereof include a method of sequentially arranging a glass layer (thin film glass), an optical film, and, if necessary, an adhesive layer (ultraviolet-curable acrylic adhesive).
  • T A and T B satisfy the above formula (1) and both T A and T B are within the range of 39 to 89%.
  • T C the average light transmittance of the adhesive layer C in the wavelength region of 380 to 780 nm
  • T B and T C satisfy the above formula (2).
  • the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
  • the thickness of the laminate of the present invention is preferably within the range of 30 to 110 ⁇ m, and more preferably within the range of 55 to 95 ⁇ m, from the viewpoint of achieving both impact resistance and contrast after bending.
  • Display Device The display device of the present invention is characterized by comprising the laminate of the present invention. It is also preferable that the optical film A is disposed closer to the viewing side of the display device than the optical film B.
  • the display device of the present invention can be obtained by attaching the laminate (cover unit) of the present invention to the surface of the display device (display unit) described below.
  • the attachment method is not particularly limited, but it is preferable to use an adhesive to attach them together.
  • the adhesive is not particularly limited, but from the viewpoints of impact resistance and contrast after bending, it is preferable to use a laminate having the above-mentioned adhesive layer as the cover unit.
  • the display device of the present invention may also have a polarizing plate between the laminate of the present invention (cover unit) and the display device (display unit) described below.
  • the laminate of the present invention can suppress external light reflection, that is, since the laminate of the present invention has some of the functions of a polarizing plate, it does not necessarily have to have a polarizing plate.
  • the term "display device” refers to a device having a display mechanism, and has a light-emitting element or a light-emitting device as a light source.
  • the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (such as a field emission display device (FED) and a surface field emission display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection type display device (such as a grating light valve (GLV) display device and a display device having a digital micromirror device (DMD)), a piezoelectric ceramic display, and the like.
  • the liquid crystal display device include a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a
  • These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images.
  • an organic EL display device or a touch panel display device is preferable, and an organic EL display device is more preferable.
  • the display device of the present invention is equipped with the laminate (cover unit) of the present invention, which makes it possible to suppress external light reflection during use and to obtain good contrast even after bending. It also provides good impact resistance that is compatible with pen input.
  • FIG. 5 and 6 show an example of application of the present invention to an organic EL display, which is an example of a display device.
  • a laminate 20 is disposed on an organic EL layer 101 via an adhesive layer C4. If necessary, other layers such as an adhesive layer D may be disposed as shown in Fig. 6.
  • an organic EL display is composed of an organic EL layer consisting of an electrode/electron transport layer/light-emitting layer/hole transport layer/transparent electrode, and a polarizing plate equipped with a retardation plate (lambda/4 plate) to improve image quality.
  • a polarizing plate equipped with a retardation plate (lambda/4 plate) to improve image quality.
  • the laminate of the present invention has some of the functions of a polarizing plate, it does not necessarily have to have a polarizing plate.
  • the display device of the present invention may also be a foldable display.
  • a foldable display is preferably a single continuous display that can be folded in half when carried, reducing its size by half and improving portability. It is further preferable that the foldable display is thin and lightweight.
  • the laminate of the present invention not only suppresses external light reflection, but also has good impact resistance and is less likely to leave creases even when folded repeatedly. It also maintains contrast even after repeated folding. Therefore, in a foldable display, it is excellent in visibility after repeated folding, specifically in suppressing image distortion at the folded parts.
  • the average light transmittance in the visible light region of the optical film and the adhesive layer C was measured by the following method.
  • the storage modulus of the adhesive layer D was measured by the following method.
  • Each optical film was conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, a UV-visible spectrophotometer (for example, “UV-2450” (manufactured by Shimadzu Corporation)) was used to measure the total light transmittance of each wavelength in the wavelength range of 380 to 780 nm, and the arithmetic average value was calculated.
  • a UV-visible spectrophotometer for example, “UV-2450” (manufactured by Shimadzu Corporation)
  • ester compound 1 A dehydration condensation reaction was carried out for 15 hours, and after completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200° C. to obtain ester compound 1.
  • the acid value of the ester compound 1 was 0.10, and the number average molecular weight was 450.
  • the cellulose ester film web was slit to a width of 1.7 m after evaporating the solvent at 35°C. It was then stretched in the TD direction (width direction of the film) by 1.3 times (stretching ratio of 30%) with a tenter while drying at a drying temperature of 160°C (also called the "heat treatment temperature” or “stretching temperature”). At this time, the amount of residual solvent (also called “residual solution”) when stretching with the tenter started was 20%. It was then dried for 15 minutes while being transported by multiple rolls in a drying device at 120°C.
  • optical film A1 It was then slit to a width of 2.2 m, knurled at both ends of the film to a width of 15 mm and a height of 10 ⁇ m, and wound around a core to obtain optical film A1.
  • the amount of residual solvent in the optical film was 0.2%, the thickness was 40 ⁇ m, and the number of windings was 6000 m.
  • Optical films A2 to A5 and A7 to A11 were prepared in the same manner as in preparation of optical film A1, except that the type of resin, the type and content of rubber particles, the type and content of colorant, and the thickness of the optical film were changed as shown in Tables I to IV. Further, an optical film A6 was prepared in the same manner as in the preparation of the optical film B1, except that the content of the colorant was changed as shown in Tables I to IV.
  • solution I The following components were charged into an 8 L polymerization apparatus equipped with a stirrer to prepare solution I.
  • Deionized water 180 parts by weight Polyoxyethylene lauryl ether phosphate 0.002 parts by weight Boric acid 0.473 parts by weight Sodium carbonate 0.047 parts by weight Sodium hydroxide 0.008 parts by weight
  • a monomer mixture (c') consisting of the following components was prepared.
  • Methyl methacrylate (methyl methacrylate) 84.6% by mass
  • n-Butyl acrylate (n-butyl acrylate) 5.9% by mass
  • Styrene 7.9% by mass
  • Allyl methacrylate (allyl methacrylate) 0.5% by mass n-Octyl mercaptan 1.1% by mass
  • the following ingredients were then added: Potassium persulfate (added as a 2% by weight aqueous solution) 0.012 parts by weight
  • the polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer made of acrylic rubber-like polymer (a)).
  • the glass transition temperature (Tg) of the soft layer calculated by averaging the glass transition temperatures of the homopolymers of the monomers constituting the acrylic rubber-like polymer (a) according to the composition ratio, was -30°C.
  • a monomer mixture (b') consisting of the following components was prepared.
  • Methyl methacrylate (methyl methacrylate) 97.5% by mass
  • n-Butyl acrylate (n-butyl acrylate) 2.5% by mass
  • the obtained methacrylic polymer (b) was poured into a 3% by mass aqueous solution of sodium sulfate to cause salting out and coagulation. Then, after repeated dehydration and washing, the mixture was dried to obtain acrylic graft copolymer particles (rubber particles) R1 having a three-layer structure.
  • the average particle size of the obtained rubber particles R1 was measured by a zeta potential/particle size measuring system "ELSZ-2000ZS" (manufactured by Otsuka Electronics Co., Ltd.) and found to be 200 nm.
  • the glass transition temperature (Tg) of the rubber particles was -30°C.
  • Optical Film B1 As a substrate, a PET film "TN100" (manufactured by Toyobo Co., Ltd., thickness 50 ⁇ m, with a release layer containing a non-silicone-based release agent) was prepared. A dope was applied onto the release layer of this PET film using a die by a backcoat method, and then dried at 80°C under an atmosphere with a solvent concentration of 0.18% by volume. Then, the substrate was peeled off to obtain an optical film B1 with a thickness of 40 ⁇ m.
  • TN100 manufactured by Toyobo Co., Ltd., thickness 50 ⁇ m, with a release layer containing a non-silicone-based release agent
  • Optical films B2 to B19 were prepared in the same manner as in preparation of optical film B1, except that the type of resin, the type and content of rubber particles, the type and content of colorant, and the thickness of the optical film were changed as shown in Tables I to IV.
  • Optical film B20 was prepared in the same manner as in preparation of optical film B1, except that the dope was directly applied to glass layer 1 described below, instead of using a PET film as the substrate.
  • Step 1 A thin film glass was prepared so that a first surface of the thin film glass was in contact with a carrier substrate having a bonding surface. Then, a contact film having adhesive force was attached to a second surface of the thin film glass opposite to the first surface. (Step 2) The thin glass was then peeled off from the carrier substrate by the highly adhesive contact film. (Step 3) The contact film was removed from the second surface of the thin glass peeled off from the carrier substrate by a weakening treatment (electromagnetic radiation exposure) that weakened the adhesive strength of the contact film.
  • a weakening treatment electromagagnetic radiation exposure
  • step 1 a thin glass film was prepared so as to be in contact with a carrier substrate having a thickness of 500 ⁇ m and to have a predetermined thickness, and then a contact film was attached to the thin glass film.
  • step 2 the thin glass film together with the contact film was peeled off from the carrier substrate in 30 seconds.
  • the contact film used was a commercially available product, "NDS4150-20.”
  • NDS4150-20 is a 150 ⁇ m thick film containing polyolefin (PO), and further has a 10 ⁇ m thick adhesive layer.
  • step 3 the exposed contact film was subjected to a weakening treatment to reduce the adhesive strength.
  • a weakening treatment ultraviolet light with a wavelength of 365 nm was irradiated onto the contact film for 10 seconds.
  • the illuminance of the ultraviolet light was 500 mW/cm 2
  • the cumulative amount of light was 500 mJ/cm 2 .
  • the adhesive strength before the weakening treatment was 11 N/25 mm, but after the weakening treatment, the adhesive strength was reduced to 0.4 N/25 mm. This allowed the contact film to be easily peeled off from the thin glass, and a glass layer 1 (thin glass 1) with a thickness of 30 ⁇ m was obtained.
  • Adhesive Layer C (4.1) Preparation of Adhesive Layer C1 (4.1.1) Preparation of UV-Curable Acrylic Adhesive Composition (a-1) A monomer mixture consisting of the following components was prepared. 2-Ethylhexyl acrylate (2EHA) 78 parts by weight N-vinyl-2-pyrrolidone (NVP) 18 parts by weight 2-hydroxyethyl acrylate (HEA) 4 parts by weight
  • Adhesive layers C2 and C3 were prepared in the same manner as in the preparation of adhesive layer C1, except that a colorant was further added and the type and content of the colorant were changed as shown in Tables I to IV.
  • the storage modulus of the adhesive layer D1 at 25° C. was 8.00 MPa.
  • a sample of the adhesive layer D was prepared by forming the adhesive layer D on the surface of a release film instead of the optical film in the same manner, and then peeling off the release film. Then, the storage modulus was measured.
  • Adhesive layers D2 and D3 were prepared in the same manner as in the preparation of adhesive layer D1, except that the thickness and storage modulus were changed as shown in Tables I to IV.
  • the storage modulus at 25° C. was 0.5 MPa and 11.00 MPa, respectively.
  • the storage modulus was adjusted by changing the ultraviolet ray irradiation conditions.
  • the front luminance (luminance measured from the normal direction of the display screen) of the display screen when the organic EL panel was displayed white was measured from a distance of 1 m using a spectroradiometer "CS2000" (manufactured by Konica Minolta Sensing Co., Ltd.) Similarly, the front luminance of the display screen when the organic EL panel was displayed black was measured.
  • CS2000 spectroradiometer
  • Front contrast (front luminance when white is displayed) / (front luminance when black is displayed) iii)
  • the front contrast was measured at any 10 points on the display screen of the organic EL panel, and the arithmetic mean value was calculated. Then, the contrast was evaluated according to the following criteria. If the evaluation was A or higher (A to AAA), the panel was deemed usable.
  • A: The front contrast is 1,500 or more and less than 1,700.
  • C The front contrast is less than 1,300.
  • AAA Will not break even when dropped from 30cm.
  • AA It will not break if dropped from 25 cm, but will break if dropped from 30 cm.
  • A It won't break if dropped from 15cm, but it will break if dropped from 25cm.
  • B It does not break when dropped from 10 cm, but it breaks when dropped from 15 cm.
  • C When dropped from 10 cm, tiny cracks were visible under a microscope.
  • D Cracks are visible when dropped from 10 cm.
  • TAC triacetyl cellulose
  • PET polyethylene terephthalate
  • COP cycloolefin resin
  • Arton G7810 manufactured by JSR Corporation
  • R1 Rubber particles obtained above (colorant)
  • P1 "Kayaset Black A-N” (manufactured by Nippon Kayaku Co., Ltd.)
  • P2 "NUBIAN BLACK PC-5857” (manufactured by Orient Chemical Industry Co., Ltd.)
  • the examples and comparative examples show that the laminate of the present invention can achieve both reflectance (suppression of external light reflection) and contrast (good contrast after bending).
  • a comparison of Examples 17 to 20 shows that impact resistance is improved when the rubber particle content is within the range of 10 to 80 mass % relative to the total mass of optical film B.
  • a comparison of Examples 22 to 25 shows that contrast and impact resistance are improved by setting the thickness of optical film B within the range of 15 to 50 ⁇ m.
  • Example 11 shows that even when the glass layer is 10 ⁇ m thick, the reflectance, contrast, and impact resistance are good.

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Abstract

The present invention addresses the problem of providing a laminate and a display device that achieve both the suppression of external light reflection and good contrast even after bending of the device.　A laminate according to the present invention has at least an optical film A, an optical film B, and a glass layer, the laminate being characterized in that the optical film A, the glass layer, and the optical film B are arranged in this order, TA and TB satisfy expression (1) below, where TA and TB are the average light transmittance of the optical film A and the average light transmittance of the optical film B, respectively, in the wavelength range of 380-780 nm, and TA and TB are both in the range of 39-89%.　Expression (1): TA > TB

Description

積層体及び表示装置Laminate and display device
　本発明は、積層体及び表示装置に関する。より詳しくは、外光反射の抑制と屈曲後の良好なコントラストを両立させた積層体等に関する。 The present invention relates to a laminate and a display device. More specifically, the present invention relates to a laminate that achieves both suppression of external light reflection and good contrast after bending.
　昨今、折り畳みや巻き取りが可能なフレキシブルディスプレイの開発が活発に行われている。フレキシブルディスプレイは、表示ユニットと、表示ユニットの保護を目的としたカバーユニットから構成される。 Recently, there has been active development of flexible displays that can be folded or rolled up. Flexible displays consist of a display unit and a cover unit that protects the display unit.
　フレキシブルディスプレイでは、カバーユニットに用いられる基材に、柔軟性が求められる。そのため、従来使用されてきたガラス基材から樹脂基材へ変更したり、ガラス基材自体を薄膜化したりすることが検討されている。中でも、高級感があり、折癖が付きにくい（耐久性）観点から、基材は、薄膜ガラス（Ｕｌｔｒａ　Ｔｈｉｎ　Ｇｌａｓｓ：「ＵＴＧ」）が主流となってきている。
　ただし、薄膜ガラスは、衝撃に弱く割れやすいため、カバーユニットに用いる際は、薄膜ガラスに保護フィルムを貼り合わせて、耐衝撃性を向上させる技術が知られている。 In flexible displays, the substrate used in the cover unit is required to have flexibility. Therefore, it has been considered to change the conventionally used glass substrate to a resin substrate or to make the glass substrate itself thinner. Among them, thin-film glass (Ultra Thin Glass: UTG) has become mainstream as a substrate from the viewpoint of luxury and resistance to folding (durability).
However, since thin film glass is weak against impact and easily breaks, a technique is known in which a protective film is attached to the thin film glass to improve impact resistance when used in a cover unit.
　一方で、ディスプレイには、外光反射の問題がある。詳しくは、外光が、カバーユニット内を透過し、表示ユニット内の金属基板の表面で反射し、その反射光を視認してしまうことにより、ディスプレイに表示される画像や映像を正しく視認できないという問題がある。
　この問題に対しては、１）表示ユニット内の金属基板に到達する外光の強さを弱める、２）金属基板の表面で反射した光の強さを視認するまでの間に弱める、の二つの方法が考えられる。すなわち、カバーユニット内を透過する外光の強さを弱め、かつカバーユニット内を透過して視認される反射光の強さを弱めることが好ましく、保護フィルムに光学特性を付与する方法が検討されている。 On the other hand, displays have a problem with external light reflection. More specifically, external light passes through the cover unit and is reflected on the surface of the metal substrate in the display unit, and the reflected light is perceived by the viewer, which makes it difficult to correctly view images and videos displayed on the display.
Two possible methods for solving this problem are: 1) weakening the intensity of external light that reaches the metal substrate in the display unit, and 2) weakening the intensity of light reflected from the surface of the metal substrate before it is visually recognized. In other words, it is preferable to weaken the intensity of external light that passes through the cover unit and the intensity of reflected light that passes through the cover unit and is visually recognized, and a method of imparting optical properties to the protective film is being considered.
　特許文献１では、発光素子が実装されている基板上に配置される封止材を、黒色にすることで、基板等に反射した光の散乱抑制と、層構成の簡略化を両立した自発光型表示体が提案されている。ただし、当該技術は、封止材に関する技術であり、薄膜ガラスを保護するフィルムに関する技術ではなかった。また、当該技術では、外光反射の抑制が十分ではなく、更なる改良が求められていた。 Patent Document 1 proposes a self-luminous display device that suppresses scattering of light reflected from the substrate and simplifies the layer structure by making the sealing material placed on the substrate on which the light-emitting elements are mounted black. However, this technology is related to the sealing material, and not to the film that protects the thin glass. Furthermore, this technology does not sufficiently suppress external light reflection, and further improvements are required.
特開２０１９－２０４９０５号公報JP 2019-204905 A
　本発明は、上記問題・状況に鑑みてなされたものであり、その解決課題は、外光反射の抑制と屈曲後の良好なコントラストを両立させた積層体及び表示装置を提供することである。 The present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a laminate and a display device that achieve both suppression of external light reflection and good contrast after bending.
　本発明者は、上記課題を解決すべく、上記問題の原因等について検討した結果、少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する積層体において、光学フィルムＡ、ガラス層、光学フィルムＢの順で配置し、光学フィルムＡ及び光学フィルムＢの３８０～７８０ｎｍの波長領域における平均光透過率ＴＡ及びＴＢを特定の範囲内とし、ＴＡをＴＢより大きくすることにより、外光反射の抑制と屈曲後の良好なコントラストを両立させた積層体を提供できることを見出し本発明に至った。
　すなわち、本発明に係る上記課題は、以下の手段により解決される。 The present inventors have investigated the causes of the above problems in order to solve the above problems, and have found that, in a laminate having at least an optical film A, an optical film B, and a glass layer, a laminate can be provided which achieves both suppression of external light reflection and good contrast after bending by arranging the optical film A, the glass layer, and the optical film B in this order, setting the average light transmittances T A and T B of the optical film A and the optical film B in the wavelength region of 380 to 780 nm within specific ranges, and making T A larger than T B , thereby completing the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.
　１．少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する積層体であって、
　前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢの順で配置され、
　前記光学フィルムＡ及び前記光学フィルムＢの、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、前記ＴＡ及び前記ＴＢが、下記式（１）を満たし、かつ前記ＴＡ及び前記ＴＢが、共に３９～８９％の範囲内である
　式（１）：　ＴＡ＞ＴＢ
　ことを特徴とする積層体。 1. A laminate having at least an optical film A, an optical film B, and a glass layer,
the optical film A, the glass layer, and the optical film B are arranged in this order;
When the average light transmittances of the optical film A and the optical film B in the wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within a range of 39 to 89%. Formula (1): T A >T B
A laminate comprising:
　２．前記ＴＡが、７０～８５％の範囲内である
　ことを特徴とする第１項に記載の積層体。 2. The laminate according to item 1, wherein the T A is in the range of 70 to 85%.
　３．前記ＴＢが、７０～８５％の範囲内である
　ことを特徴とする第１項又は第２項に記載の積層体。 3. The laminate according to item 1 or 2, wherein the T B is in the range of 70 to 85%.
　４．少なくとも、前記光学フィルムＢが、ゴム粒子を含有する
　ことを特徴とする第１項又は第２項に記載の積層体。 4. The laminate according to item 1 or 2, wherein at least the optical film B contains rubber particles.
　５．前記ゴム粒子の含有量が、前記光学フィルムＢの全質量に対して、１０～８０質量％の範囲内である
　ことを特徴とする第４項に記載の積層体。 5. The laminate according to item 4, wherein the content of the rubber particles is within a range of 10 to 80% by mass with respect to the total mass of the optical film B.
　６．前記光学フィルムＢが、熱可塑性（メタ）アクリル系樹脂を含有する
　ことを特徴とする第１項又は第２項に記載の積層体。 6. The laminate according to item 1 or 2, wherein the optical film B contains a thermoplastic (meth)acrylic resin.
　７．前記光学フィルムＢの厚さが、１５～５０μｍの範囲内である
　ことを特徴とする第１項又は第２項に記載の積層体。 7. The laminate according to item 1 or 2, wherein the thickness of the optical film B is within a range of 15 to 50 μm.
　８．前記ガラス層の厚さが、１０～３０μｍの範囲内である
　ことを特徴とする第１項又は第２項に記載の積層体。 8. The laminate according to claim 1 or 2, wherein the thickness of the glass layer is within a range of 10 to 30 μm.
　９．当該積層体が、粘着層Ｃを更に有し、
　前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢ、前記粘着層Ｃの順で配置され、
　前記粘着層Ｃの３８０～７８０ｎｍの波長領域における平均光透過率をＴＣとしたとき、前記ＴＢ及び前記ＴＣが、下記式（２）を満たす
　式（２）：　ＴＢ＜ＴＣ
　ことを特徴とする第１項又は第２項に記載の積層体。 9. The laminate further has an adhesive layer C,
The optical film A, the glass layer, the optical film B, and the adhesive layer C are arranged in this order,
When the average light transmittance of the adhesive layer C in the wavelength region of 380 to 780 nm is defined as T C , the T B and the T C satisfy the following formula (2): T B <T C
3. The laminate according to claim 1 or 2,
　１０．当該積層体が、粘着層Ｄを更に有し、
　前記光学フィルムＡ、前記ガラス層、前記粘着層Ｄ、前記光学フィルムＢの順で配置され、
　前記粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内である
　ことを特徴とする第１項又は第２項に記載の積層体。 10. The laminate further has an adhesive layer D,
The optical film A, the glass layer, the adhesive layer D, and the optical film B are arranged in this order,
3. The laminate according to claim 1, wherein the adhesive layer D has a storage modulus at 25° C. in the range of 0.5 to 8 MPa.
　１１．第１項又は第２項に記載の積層体を具備する
　ことを特徴とする表示装置。 11. A display device comprising the laminate according to claim 1 or 2.
　１２．前記光学フィルムＡが、前記光学フィルムＢよりも当該表示装置の視認側に配置される
　ことを特徴とする第１１項に記載の表示装置。 12. The display device according to item 11, wherein the optical film A is disposed closer to a viewing side of the display device than the optical film B.
　本発明の上記手段により、外光反射の抑制と屈曲後の良好なコントラストを両立させた積層体及び表示装置を提供することができる。 The above-mentioned means of the present invention make it possible to provide a laminate and a display device that achieve both suppression of external light reflection and good contrast after bending.
　本発明の効果の発現機構又は作用機構については、明確にはなっていないが、以下のように推察している。 The mechanism by which the effects of this invention are expressed or acted upon is not clear, but is speculated as follows.
　本発明の積層体は、光学フィルム及び薄膜ガラス（ガラス層）を有する積層体であって、薄膜ガラスの両面に、光学フィルムを貼り合わせる構成としている。このような構成とすることにより、衝撃に弱く割れやすい薄膜ガラスを保護できると考えられる。 The laminate of the present invention is a laminate having an optical film and thin glass (glass layer), and is configured such that the optical film is bonded to both sides of the thin glass. It is believed that this configuration can protect the thin glass, which is vulnerable to impacts and easily breaks.
　ディスプレイ（表示装置）における外光反射は、入射した外光が、各層の界面で反射することにより生じると考えられる。特に、薄膜ガラスをカバーユニットに用いる際は、主に、視認側の光学フィルムＡの表面、薄膜ガラスの表面、及び表示ユニット内の金属基板の表面での反射が大きく影響すると考えられる。このため、各表面で反射する光の強さを弱めることが好ましい。 It is believed that external light reflection in a display (display device) occurs when incident external light is reflected at the interfaces of each layer. In particular, when thin-film glass is used for the cover unit, it is believed that reflections from the surface of optical film A on the viewing side, the surface of the thin-film glass, and the surface of the metal substrate in the display unit have a large effect. For this reason, it is preferable to reduce the intensity of light reflected from each surface.
　一般的に、物体に入射した光は、物体の表面で反射する、物体に吸収される又は物体を透過する。物体の表面で反射する光の強さを弱めるためには、物体に入射する光の強さを弱める、物体により吸収される、又は物体を透過する光の強さを強める必要がある。 Generally, light incident on an object is reflected from the object's surface, absorbed by the object, or transmitted through the object. In order to reduce the intensity of light reflected from the object's surface, it is necessary to reduce the intensity of light incident on the object, or to increase the intensity of light absorbed by the object, or transmitted through the object.
　薄膜ガラスの表面に到達する（入射する）光の強さは、光学フィルムＡの３８０～７８０ｎｍの波長領域における平均光透過率（以下、単に、「光透過率」ともいう。）を低くすることにより、弱めることができる。同様に、金属基板の表面に到達する光の強さは、光学フィルムＡ及び光学フィルムＢの光透過率を低くすることにより、弱めることができる。したがって、光学フィルムＡ及び光学フィルムＢの光透過率を、比較的低くする、具体的には、８９％以下とすることにより、薄膜ガラス及び金属基板での外光反射を抑制できる。 The intensity of light that reaches (is incident on) the surface of the thin glass can be weakened by lowering the average light transmittance (hereinafter simply referred to as "light transmittance") of optical film A in the wavelength range of 380 to 780 nm. Similarly, the intensity of light that reaches the surface of the metal substrate can be weakened by lowering the light transmittance of optical film A and optical film B. Therefore, by making the light transmittance of optical film A and optical film B relatively low, specifically, 89% or less, it is possible to suppress external light reflection on the thin glass and metal substrate.
　また、光学フィルムＡは最も視認側に配置されているため、光学フィルムＡの表面に到達する（入射する）光の強さを弱めることはできない。このため、光学フィルムＡの光透過率を比較的高くすることにより、反射する光の強さを弱めることができる。したがって、光学フィルムＡの光透過率を光学フィルムＢの光透過率よりも高くすることにより、光学フィルムＡ、薄膜ガラスでの外光反射を効率よく抑制できる。
　しかし、光学フィルムＡを透過した外光が、金属基板に到達してしまうと、金属基板からの外光反射により視認性が劣化してしまう。そのため、金属基板へ到達する外光を弱める、及び金属基板で反射した外光を弱めるために、より金属基板に近い光学フィルムＢの透過率を、光学フィルムＡの透過率より低くすることにより、金属基板での外光反射を効率よく抑制できる。 In addition, since optical film A is disposed on the most visible side, the intensity of light that reaches (enters) the surface of optical film A cannot be weakened. For this reason, the intensity of reflected light can be weakened by relatively increasing the light transmittance of optical film A. Therefore, by making the light transmittance of optical film A higher than that of optical film B, external light reflection at optical film A and thin glass can be efficiently suppressed.
However, when the external light transmitted through optical film A reaches the metal substrate, the visibility is deteriorated due to the reflection of the external light from the metal substrate. Therefore, in order to weaken the external light reaching the metal substrate and the external light reflected by the metal substrate, the transmittance of optical film B, which is closer to the metal substrate, is made lower than the transmittance of optical film A, thereby making it possible to efficiently suppress the reflection of the external light on the metal substrate.
　ただし、光学フィルムＡ及び光学フィルムＢの光透過率を低くしすぎると、表示ユニット内の発光素子からの光を十分に視認側へ透過できない。したがって、光学フィルムＡ及び光学フィルムＢが適度に光を透過することにより、表示装置において、良好なコントラストが得られる。 However, if the light transmittance of optical film A and optical film B is made too low, the light from the light-emitting elements in the display unit cannot be sufficiently transmitted to the viewing side. Therefore, by allowing optical film A and optical film B to transmit light appropriately, good contrast can be obtained in the display device.
　なお、本発明の積層体は、折り曲げ可能な表示装置（フレキシブルディスプレイ）に用いるため、繰り返し折り曲げを行った後（屈曲後）の表示装置においても、良好なコントラストが得られる必要がある。本発明者が、検討を重ねたところ、光学フィルムＡ及び光学フィルムＢの光透過率を３９％以上とすることにより、繰り返し折り曲げを行った後の表示装置においても、良好なコントラストが得られることがわかった。 In addition, since the laminate of the present invention is used in a foldable display device (flexible display), it is necessary that the display device obtain good contrast even after repeated folding (bending). After extensive research, the inventors found that by setting the light transmittance of optical film A and optical film B to 39% or more, good contrast can be obtained even in the display device after repeated folding.
本発明の積層体の基本的な層構成の断面図1 is a cross-sectional view of a basic layer structure of a laminate of the present invention. 本発明の積層体の基本的な層構成の断面図1 is a cross-sectional view of a basic layer structure of a laminate of the present invention. 本発明の積層体の基本的な層構成の断面図1 is a cross-sectional view of a basic layer structure of a laminate of the present invention. 薄膜ガラスの作製方法の一例を示す模式図Schematic diagram showing an example of a method for producing thin glass 本発明の表示装置の一例である有機ＥＬディスプレイへの適用例An example of application of the present invention to an organic EL display, which is an example of a display device. 本発明の表示装置の一例である有機ＥＬディスプレイへの適用例An example of application of the present invention to an organic EL display, which is an example of a display device.
　本発明の積層体は、少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する積層体であって、前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢの順で配置され、前記光学フィルムＡ及び前記光学フィルムＢの、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、前記ＴＡ及び前記ＴＢが、下記式（１）を満たし、かつ前記ＴＡ及び前記ＴＢが、共に３９～８９％の範囲内であることを特徴とする。
　式（１）：　ＴＡ＞ＴＢ
　この特徴は、下記実施態様に共通する又は対応する技術的特徴である。 The laminate of the present invention is a laminate having at least an optical film A, an optical film B, and a glass layer, and is arranged in the order of the optical film A, the glass layer, and the optical film B, and is characterized in that, when the average light transmittances of the optical film A and the optical film B in a wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within the range of 39 to 89%.
Formula (1): TA > TB
This feature is a technical feature common to or corresponding to the following embodiments.
　本発明の実施形態としては、外光反射の抑制と屈曲後の良好なコントラストを両立できる観点から、前記ＴＡが、７０～８５％の範囲内であることが好ましい。 In an embodiment of the present invention, from the viewpoint of achieving both suppression of external light reflection and good contrast after bending, the T A is preferably within the range of 70 to 85%.
　本発明の実施形態としては、外光反射の抑制と屈曲後の良好なコントラストを両立できる観点から、前記ＴＢが、７０～８５％の範囲内であることが好ましい。 In an embodiment of the present invention, from the viewpoint of achieving both suppression of external light reflection and good contrast after bending, the T B is preferably within the range of 70 to 85%.
　本発明の実施形態としては、耐衝撃性の観点から、少なくとも、前記光学フィルムＢが、ゴム粒子を含有することが好ましい。 In one embodiment of the present invention, from the viewpoint of impact resistance, it is preferable that at least the optical film B contains rubber particles.
　本発明の実施形態としては、耐衝撃性の観点から、前記ゴム粒子の含有量が、前記光学フィルムＢの全質量に対して、１０～８０質量％の範囲内であることが好ましい。 In one embodiment of the present invention, from the viewpoint of impact resistance, it is preferable that the content of the rubber particles is within the range of 10 to 80 mass % relative to the total mass of the optical film B.
　本発明の実施形態としては、保管性及び透明性の観点から、前記光学フィルムＢが、熱可塑性（メタ）アクリル系樹脂を含有することが好ましい。 In one embodiment of the present invention, from the viewpoints of storage stability and transparency, it is preferable that the optical film B contains a thermoplastic (meth)acrylic resin.
　本発明の実施形態としては、屈曲後の良好なコントラスト及び耐衝撃性の観点から、前記光学フィルムＢの厚さが、１５～５０μｍの範囲内であることが好ましい。 In one embodiment of the present invention, from the viewpoint of good contrast after bending and impact resistance, it is preferable that the thickness of the optical film B is within the range of 15 to 50 μm.
　本発明の実施形態としては、積層体の薄型化の観点から、前記ガラス層の厚さが、１０～３０μｍの範囲内であることが好ましい。 In one embodiment of the present invention, from the viewpoint of making the laminate thinner, it is preferable that the thickness of the glass layer is within the range of 10 to 30 μm.
　本発明の実施形態としては、屈曲後の良好なコントラスト及び耐衝撃性の観点から、当該積層体が、粘着層Ｃを更に有し、前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢ、前記粘着層Ｃの順で配置され、前記粘着層Ｃの３８０～７８０ｎｍの波長領域における平均光透過率をＴＣとしたとき、前記ＴＢ及び前記ＴＣが、下記式（２）を満たすことが好ましい。
　式（２）：　ＴＢ＜ＴＣ As an embodiment of the present invention, from the viewpoint of good contrast and impact resistance after bending, it is preferable that the laminate further has an adhesive layer C, and is arranged in the order of the optical film A, the glass layer, the optical film B, and the adhesive layer C, and when the average light transmittance of the adhesive layer C in a wavelength region of 380 to 780 nm is T C , the T B and the T C satisfy the following formula (2).
Equation (2): TB < TC
　本発明の実施形態としては、耐衝撃性の観点から、当該積層体が、粘着層Ｄを更に有し、前記光学フィルムＡ、前記ガラス層、前記粘着層Ｄ、前記光学フィルムＢの順で配置され、前記粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内であることが好ましい。 In one embodiment of the present invention, from the viewpoint of impact resistance, it is preferable that the laminate further includes an adhesive layer D, and that the optical film A, the glass layer, the adhesive layer D, and the optical film B are arranged in this order, and that the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
　本発明の表示装置は、本発明の積層体を具備することを特徴とする。
　また、本発明の効果発現の観点から、前記光学フィルムＡが、前記光学フィルムＢよりも当該表示装置の視認側に配置されることが好ましい。 The display device of the present invention is characterized by comprising the laminate of the present invention.
In order to obtain the effects of the present invention, it is preferable that the optical film A is disposed closer to the viewing side of the display device than the optical film B.
　以下、本発明とその構成要素、及び本発明を実施するための形態・態様について詳細な説明をする。なお、本願において、「～」は、その前後に記載される数値を下限値及び上限値として含む意味で使用する。 The present invention, its components, and the forms and modes for implementing the invention are described in detail below. In this application, "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.
　１．積層体の概要
　本発明の積層体は、少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する積層体であって、前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢの順で配置され、前記光学フィルムＡ及び前記光学フィルムＢの、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、前記ＴＡ及び前記ＴＢが、下記式（１）を満たし、かつ前記ＴＡ及び前記ＴＢが、共に３９～８９％の範囲内であることを特徴とする。
　式（１）：　ＴＡ＞ＴＢ 1. Overview of the Laminate The laminate of the present invention is a laminate having at least an optical film A, an optical film B, and a glass layer, which is arranged in the order of the optical film A, the glass layer, and the optical film B, and is characterized in that, when the average light transmittances of the optical film A and the optical film B in a wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within the range of 39 to 89%.
Formula (1): TA > TB
　なお、本発明において、「光学フィルム」とは、フィルムの有するいくつかの機能の一つとして、３８０～７８０ｎｍの波長領域における平均光透過率が３９～８９％の範囲内であるという光学機能を有するフィルムのことをいう。 In the present invention, the term "optical film" refers to a film that has an optical function in which, as one of several functions of the film, the average light transmittance in the wavelength range of 380 to 780 nm is within the range of 39 to 89%.
　図１は、本発明の積層体の基本的な層構成の断面図である。積層体１０は、光学フィルムＡ１、ガラス層３及び光学フィルムＢ２を有する。
　図２及び図３は、粘着層を有する場合の、本発明の積層体の基本的な層構成の断面図である。積層体２０は、光学フィルムＡ１、ガラス層３、光学フィルムＢ２及び粘着層Ｃ４を有する。積層体３０は、光学フィルムＡ１、ガラス層３、粘着層Ｄ５、光学フィルムＢ２、粘着層Ｃ４を有する。 1 is a cross-sectional view of a basic layer structure of a laminate of the present invention. The laminate 10 has an optical film A1, a glass layer 3, and an optical film B2.
2 and 3 are cross-sectional views of the basic layer structure of the laminate of the present invention when an adhesive layer is included. The laminate 20 includes an optical film A1, a glass layer 3, an optical film B2, and an adhesive layer C4. The laminate 30 includes an optical film A1, a glass layer 3, an adhesive layer D5, an optical film B2, and an adhesive layer C4.
　なお、必要に応じて、各層間に他の層が配置されていてもよい。
　また、粘着層Ｃ４と光学フィルムＢ２の境界は必ずしも明確である必要はなく、粘着層４と光学フィルムＢ２が一体化した層構成であってもよい。同様に、粘着層Ｄ５と光学フィルムＢ２の境界は必ずしも明確である必要はなく、粘着層Ｄ５と光学フィルムＢ２が一体化した層構成であってもよい。 If necessary, other layers may be disposed between the layers.
In addition, the boundary between the adhesive layer C4 and the optical film B2 does not necessarily have to be clear, and the adhesive layer C4 and the optical film B2 may be integrated into a layer structure. Similarly, the boundary between the adhesive layer D5 and the optical film B2 does not necessarily have to be clear, and the adhesive layer D5 and the optical film B2 may be integrated into a layer structure.
　粘着層Ｃ又は粘着層Ｄと、光学フィルムＢが一体化した層構成（以下、「一体型フィルム」ともいう。）である場合、一体型フィルムの３８０～７８０ｎｍの波長領域における平均光透過率ＴＥが、ＴＢと同様の条件を満たすのであれば、本発明に該当する。 In the case of a layer structure in which the adhesive layer C or the adhesive layer D and the optical film B are integrated (hereinafter also referred to as an "integral film"), if the average light transmittance T E in the wavelength region of 380 to 780 nm of the integrated film satisfies the same conditions as those of T B , it falls under the present invention.
　本発明の積層体では、光学フィルムで、薄膜ガラス（ガラス層）の両面を保護し、さらに、光学フィルムの光透過率を特定の範囲内とする。これにより、本発明の積層体をカバーユニットとして使用した際に、外光反射の抑制と屈曲後の良好なコントラストを両立できる。 In the laminate of the present invention, both sides of the thin glass (glass layer) are protected with an optical film, and the optical transmittance of the optical film is set within a specific range. This makes it possible to achieve both suppression of external light reflection and good contrast after bending when the laminate of the present invention is used as a cover unit.
　２．積層体の構成
　本発明の積層体は、少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する。また、必要に応じて、粘着層等を有していてもよい。粘着層は、後述する粘着層Ｃ又は粘着層Ｄであることが好ましいが、特に制限されない。
　以下、各層について説明する。 2. Structure of the Laminate The laminate of the present invention has at least an optical film A, an optical film B, and a glass layer. If necessary, it may have an adhesive layer or the like. The adhesive layer is preferably an adhesive layer C or an adhesive layer D described later, but is not particularly limited.
Each layer will be described below.
　（１）光学フィルム
　本発明に係る光学フィルムＡ及び光学フィルムＢは、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、ＴＡ及びＴＢが、下記式（１）を満たし、かつＴＡ及びＴＢが、共に３９～８９％の範囲内であることを特徴とする。
　式（１）：　ＴＡ＞ＴＢ (1) Optical Film Optical film A and optical film B according to the present invention are characterized in that, when average light transmittances in a wavelength region of 380 to 780 nm are T A and T B , respectively, T A and T B satisfy the following formula (1) and both T A and T B are within the range of 39 to 89%.
Formula (1): TA > TB
　光学フィルムＡ及び光学フィルムＢを構成する材料は、同一であっても、同一でなくてもよい。 The materials constituting optical film A and optical film B may or may not be the same.
　光学フィルムの光透過率は、光学フィルムに着色剤を含有させることにより調整できる。また、光学フィルムを構成する材料（樹脂、ゴム粒子等）の種類、含有量等によっても調整できる。 The light transmittance of an optical film can be adjusted by adding a colorant to the optical film. It can also be adjusted by the type and content of the materials (resin, rubber particles, etc.) that make up the optical film.
　（１．１）光学フィルムの構成材料
　本発明に係る光学フィルムは、樹脂で構成されることが好ましい。また、必要に応じて、ゴム粒子、着色剤、微粒子等を更に含有することが好ましい。 (1.1) Constituent Materials of Optical Film The optical film according to the present invention is preferably made of a resin, and further preferably contains rubber particles, a colorant, fine particles, etc., as necessary.
　（１．１．１）光学フィルム用樹脂
　光学フィルムに用いられる樹脂（光学フィルム用樹脂）は、特に制限されず、セルロースエステル、シクロオレフィン系樹脂、フマル酸ジエステル系樹脂、ポリプロピレン、（メタ）アクリル系樹脂、ポリエステル、ポリアリレート、ポリイミド、スチレン系樹脂又はその複合樹脂、等が挙げられる。 (1.1.1) Resin for Optical Film The resin used in the optical film (resin for optical film) is not particularly limited, and examples thereof include cellulose ester, cycloolefin-based resin, fumaric acid diester-based resin, polypropylene, (meth)acrylic resin, polyester, polyarylate, polyimide, styrene-based resin, and composite resin thereof.
　中でも、折り曲げ耐性、光学特性等の観点から、カルボニル基を側鎖に有する直鎖状高分子材料を含有すること、又は環状構造を主鎖に有する高分子材料を含有することが好ましい。具体的には、（メタ）アクリル系樹脂、スチレン・（メタ）アクリレート共重合体、シクロオレフィン系樹脂、ポリイミド又はセルロースエステルであることが好ましい。 Among them, from the viewpoint of bending resistance, optical properties, etc., it is preferable to contain a linear polymer material having a carbonyl group in the side chain, or a polymer material having a cyclic structure in the main chain. Specifically, it is preferable to use a (meth)acrylic resin, a styrene-(meth)acrylate copolymer, a cycloolefin resin, a polyimide, or a cellulose ester.
　（１．１．１．１）（メタ）アクリル系樹脂
　（メタ）アクリル系樹脂は、少なくともメタクリル酸メチルに由来する構造単位（Ｕ１）を有することが好ましい。中でも、光学フィルムの光弾性係数を小さくでき、吸湿膨張によるムラの発生を抑制できる観点から、熱可塑性（メタ）アクリル系樹脂は、フェニルマレイミドに由来する構造単位（Ｕ２）を更に有することが好ましい。 (1.1.1.1) (Meth)acrylic resin The (meth)acrylic resin preferably has at least a structural unit (U1) derived from methyl methacrylate. In particular, from the viewpoint of reducing the photoelastic coefficient of the optical film and suppressing the occurrence of unevenness due to moisture absorption expansion, the thermoplastic (meth)acrylic resin preferably further has a structural unit (U2) derived from phenylmaleimide.
　また、（メタ）アクリル系樹脂は、上記以外の他の構造単位を更に有していてもよい。光学フィルムに靱性を付与できる観点から、アクリル酸アルキルエステルに由来する構造単位（Ｕ３）を更に有することがより好ましい。 The (meth)acrylic resin may further have structural units other than those described above. From the viewpoint of imparting toughness to the optical film, it is more preferable that the (meth)acrylic resin further has a structural unit (U3) derived from an alkyl acrylate ester.
　すなわち、熱可塑性（メタ）アクリル系樹脂は、メタクリル酸メチルに由来する構造単位（Ｕ１）と、フェニルマレイミドに由来する構造単位（Ｕ２）と、アクリル酸アルキルエステルに由来する構造単位（Ｕ３）とを有することが好ましい。 In other words, the thermoplastic (meth)acrylic resin preferably has a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and a structural unit (U3) derived from an alkyl acrylate.
　メタクリル酸メチルに由来する構造単位（Ｕ１）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して、５０～９５質量％の範囲内であることが好ましく、７０～９０質量％の範囲内であることがより好ましい。 The content of the structural unit (U1) derived from methyl methacrylate is preferably within the range of 50 to 95% by mass, and more preferably within the range of 70 to 90% by mass, relative to all structural units constituting the (meth)acrylic resin.
　フェニルマレイミドに由来する構造単位（Ｕ２）は、比較的剛直な構造を有するため、光学フィルムの機械的強度を高めることができる。また、フェニルマレイミドに由来する構造単位（Ｕ２）は、比較的嵩高い構造を有し、つまり、樹脂マトリクス中に、ゴム粒子が移動できるミクロな空隙を有する。これにより、ゴム粒子を光学フィルムの表層部に偏在させやすくできる。なお、ゴム粒子については、詳しくは後述する。 The structural unit (U2) derived from phenylmaleimide has a relatively rigid structure, and therefore can increase the mechanical strength of the optical film. In addition, the structural unit (U2) derived from phenylmaleimide has a relatively bulky structure, that is, it has microscopic voids in the resin matrix through which the rubber particles can move. This makes it easier to concentrate the rubber particles in the surface layer of the optical film. The rubber particles will be described in more detail later.
　フェニルマレイミドに由来する構造単位（Ｕ２）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して、１～２５質量％の範囲内であることが好ましく、７～１５質量％の範囲内であることがより好ましい。
　フェニルマレイミドに由来する構造単位（Ｕ２）の含有量が、１質量％以上であることにより、光学フィルムの高湿度環境下での保存性に優れる。また、２５質量％以下であることにより、光学フィルムに十分な靱性を付与できる。 The content of the structural unit (U2) derived from phenylmaleimide is preferably within a range of 1 to 25 mass%, and more preferably within a range of 7 to 15 mass%, based on all structural units constituting the (meth)acrylic resin.
When the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, the optical film has excellent storage stability in a high humidity environment, and when the content is 25% by mass or less, the optical film can have sufficient toughness.
　アクリル酸アルキルエステルに由来する構造単位（Ｕ３）は、樹脂に適度な柔軟性を付与できる。そのため、例えば、フェニルマレイミドに由来する構造単位（Ｕ２）と組み合わせることにより、光学フィルムに十分な靱性を付与できる。 The structural unit (U3) derived from an alkyl acrylate ester can impart moderate flexibility to the resin. Therefore, for example, by combining it with the structural unit (U2) derived from phenylmaleimide, sufficient toughness can be imparted to the optical film.
　アクリル酸アルキルエステルは、アルキル部分の炭素数が１～７、好ましくは１～５のアクリル酸アルキルエステルであることが好ましい。
　アクリル酸アルキルエステルとしては、例えば、アクリル酸メチル（メチルアクリレート）、アクリル酸エチル（エチルアクリレート）、アクリル酸プロピル（プロピルアクリレート）、アクリル酸ブチル（ブチルアクリレート）、アクリル酸２－ヒドロキシエチル（２－ヒドロキシエチルアクリレート）、アクリル酸ヘキシル（へキシルアクリレート）、アクリル酸２－エチルヘキシル（２－エチルへキシルアクリレート）等が挙げられる。 The alkyl acrylate is preferably an alkyl acrylate having 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms in the alkyl portion.
Examples of acrylic acid alkyl esters include methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), propyl acrylate (propyl acrylate), butyl acrylate (butyl acrylate), 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate), hexyl acrylate (hexyl acrylate), and 2-ethylhexyl acrylate (2-ethylhexyl acrylate).
　アクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して、１～２５質量％の範囲内であることが好ましく、５～１５質量％の範囲内であることがより好ましい。
　アクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量が、１質量％以上であることにより、（メタ）アクリル系樹脂に適度な柔軟性を付与でき、光学フィルムの破断を抑制できる。また、２５質量％以下であることにより、（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）の低下を抑制でき、光学フィルムの高湿度環境下での保存性に優れる。 The content of the structural unit (U3) derived from an alkyl acrylate is preferably within a range of 1 to 25 mass%, and more preferably within a range of 5 to 15 mass%, based on all structural units constituting the (meth)acrylic resin.
The content of the structural unit (U3) derived from an alkyl acrylate of 1% by mass or more can provide the (meth)acrylic resin with appropriate flexibility and can suppress breakage of the optical film, while the content of the structural unit (U3) derived from an alkyl acrylate of 25% by mass or less can suppress a decrease in the glass transition temperature (Tg) of the (meth)acrylic resin and can provide the optical film with excellent storage stability under high humidity conditions.
　フェニルマレイミドに由来する構造単位（Ｕ２）の、フェニルマレイミドに由来する構造単位（Ｕ２）とアクリル酸アルキルエステルに由来する構造単位（Ｕ３）の合計量に対する比率は、２０～７０質量％の範囲内であることが好ましい。当該比率が、２０質量％以上であることにより、光学フィルムの貯蔵弾性率を高めやすく、７０質量％以下であることにより、光学フィルムに十分な靱性を付与できる。 The ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from an alkyl acrylate is preferably within the range of 20 to 70% by mass. When this ratio is 20% by mass or more, it is easy to increase the storage modulus of the optical film, and when it is 70% by mass or less, sufficient toughness can be imparted to the optical film.
　（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）は、１００℃以上であることが好ましく、１２０～１５０℃の範囲内であることがより好ましい。上記範囲内であることにより、光学フィルムの耐熱性を高めることができる。なお、（メタ）アクリル系樹脂のＴｇを調整するためには、例えば、フェニルマレイミドに由来する構造単位（Ｕ２）やアクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量を調整することが好ましい。 The glass transition temperature (Tg) of the (meth)acrylic resin is preferably 100°C or higher, and more preferably within the range of 120 to 150°C. By keeping it within the above range, the heat resistance of the optical film can be improved. In order to adjust the Tg of the (meth)acrylic resin, it is preferable to adjust the content of, for example, the structural unit (U2) derived from phenylmaleimide or the structural unit (U3) derived from an alkyl acrylate.
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、１０万以上であることが好ましく、１００万以上であることがより好ましく、１５０万～３００万の範囲内であることが更に好ましい。熱可塑性（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）が、１０万以上であることにより、光学フィルムの靱性を高めることができる。これにより、光学フィルムの搬送時における搬送張力によって、光学フィルムが破断するのを抑制できる。また、光学フィルムの貯蔵弾性率を高めることができるため、巻き変形を抑制できる。 The weight-average molecular weight (Mw) of the (meth)acrylic resin is preferably 100,000 or more, more preferably 1,000,000 or more, and even more preferably in the range of 1,500,000 to 3,000,000. By having the weight-average molecular weight (Mw) of the thermoplastic (meth)acrylic resin be 100,000 or more, the toughness of the optical film can be increased. This makes it possible to prevent the optical film from breaking due to the transport tension during transport. In addition, the storage modulus of the optical film can be increased, making it possible to suppress winding deformation.
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、下記の方法で測定できる。また、その他の樹脂等の重量平均分子量（Ｍｗ）及び数平均分子量についても、下記の方法で測定できる。 The weight average molecular weight (Mw) of the (meth)acrylic resin can be measured by the following method. The weight average molecular weight (Mw) and number average molecular weight of other resins can also be measured by the following method.
　＜ゲルパーミエーションクロマトグラフィー＞
　溶媒：　　　メチレンクロライド
　カラム：　　Ｓｈｏｄｅｘ　Ｋ８０６、Ｋ８０５、Ｋ８０３Ｇ（昭和電工（株）製を３本接続して使用した）
　カラム温度：２５℃
　試料濃度：　０．１質量％
　検出器：　　ＲＩ　Ｍｏｄｅｌ　５０４（ＧＬサイエンス社製）
　ポンプ：　　Ｌ６０００（日立製作所（株）製）
　流量：　　　１．０ｍＬ／ｍｉｎ
　校正曲線：　標準ポリスチレンＳＴＫ　ｓｔａｎｄａｒｄ　ポリスチレン（東ソー（株）製）Ｍｗ＝５００～２８０００００の範囲内の１３サンプルによる校正曲線を使用した。１３サンプルは、ほぼ等間隔に用いることが好ましい。 <Gel permeation chromatography>
Solvent: methylene chloride Column: Shodex K806, K805, K803G (three columns manufactured by Showa Denko K.K. were connected and used)
Column temperature: 25°C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Sciences)
Pump: L6000 (Hitachi, Ltd.)
Flow rate: 1.0 mL/min
Calibration curve: A calibration curve was used using 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) having Mw of 500 to 2,800,000. It is preferable to use the 13 samples at approximately equal intervals.
　（１．１．１．２）スチレン・（メタ）アクリレート共重合体
　スチレン・アクリル樹脂は、少なくとも、スチレン単量体と、（メタ）アクリル酸エステル単量体とを付加重合させて合成される。 (1.1.1.2) Styrene-(meth)acrylate copolymer Styrene-acrylic resin is synthesized by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer.
　スチレン・（メタ）アクリレート共重合体（以下、「スチレン・アクリル樹脂」ともいう。）を用いることにより、光学フィルムに透明性を付与できる。また、スチレン部分の共重合比率によって吸湿膨張係数を調整できるため、共重合比率を調整することによって光学フィルムや積層体のカールを制御できる。 The use of styrene-(meth)acrylate copolymers (hereinafter also referred to as "styrene-acrylic resins") can impart transparency to optical films. In addition, the moisture absorption expansion coefficient can be adjusted by the copolymerization ratio of the styrene portion, so curling of optical films and laminates can be controlled by adjusting the copolymerization ratio.
　スチレン単量体としては、ＣＨ２＝ＣＨ－Ｃ６Ｈ５の構造式で表されるスチレンの他に、スチレン構造中に公知の側鎖や官能基を有するスチレン誘導体が挙げられる。 Examples of the styrene monomer include styrene represented by the structural formula CH 2 ═CH—C 6 H 5 , as well as styrene derivatives having a known side chain or functional group in the styrene structure.
　また、（メタ）アクリル酸エステル単量体としては、ＣＨ（Ｒ１）＝ＣＨＣＯＯＲ２（Ｒ１は水素原子又はメチル基を表し、Ｒ２は炭素数が１～２４のアルキル基を表す。）で表されるアクリル酸エステルやメタクリル酸エステルが挙げられる。その他、これらのエステルの構造中に公知の側鎖や官能基を有するアクリル酸エステル誘導体やメタクリル酸エステル誘導体が挙げられる。 Examples of the (meth)acrylic acid ester monomer include acrylic acid esters and methacrylic acid esters represented by CH(R 1 )═CHCOOR 2 (R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 24 carbon atoms). Other examples include acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters.
　スチレン単量体の例としては、スチレン、ｏ－メチルスチレン、ｍ－メチルスチレン、ｐ－メチルスチレン、α－メチルスチレン、ｐ－フェニルスチレン、ｐ－エチルスチレン、２，４－ジメチルスチレン、ｐ－ｔｅｒｔ－ブチルスチレン、ｐ－ｎ－ヘキシルスチレン、ｐ－ｎ－オクチルスチレン、ｐ－ｎ－ノニルスチレン、ｐ－ｎ－デシルスチレン及びｐ－ｎ－ドデシルスチレンが挙げられる。 Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene.
　（メタ）アクリル酸エステル単量体の例としては、メチルアクリレート、エチルアクリ
レート、イソプロピルアクリレート、ｎ－ブチルアクリレート、ｔ－ブチルアクリレート、イソブチルアクリレート、ｎ－オクチルアクリレート、２－エチルヘキシルアクリレート（２ＥＨＡ）、ステアリルアクリレート、ラウリルアクリレート及びフェニルアクリレートなどのアクリル酸エステル単量体；メチルメタクリレート、エチルメタクリレート、ｎ－ブチルメタクリレート、イソプロピルメタクリレート、イソブチルメタクリレート、ｔ－ブチルメタクリレート、ｎ－オクチルメタクリレート、２－エチルヘキシルメタクリレート、ステアリルメタクリレート、ラウリルメタクリレート、フェニルメタクリレート、ジエチルアミノエチルメタクリレート、ジメチルアミノエチルメタクリレートなどのメタクリル酸エステル；が挙げられる。 Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate (2EHA), stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.
　なお、本明細書中、「（メタ）アクリル酸エステル単量体」とは、「アクリル酸エステル単量体」と「メタクリル酸エステル単量体」との総称であり、それらの一方又は両方を意味する。例えば、「（メタ）アクリル酸メチル」は、「アクリル酸メチル」及び「メタクリル酸メチル」の一方又は両方を意味する。 In this specification, "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer" and means one or both of them. For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate".
　上記（メタ）アクリル酸エステル単量体は、一種で用いても、二種以上併用してもよい。
　例えば、スチレン単量体と二種以上のアクリル酸エステル単量体とを用いて共重合体を形成すること、スチレン単量体と二種以上のメタクリル酸エステル単量体とを用いて共重合体を形成すること、及び、スチレン単量体とアクリル酸エステル単量体及びメタクリル酸エステル単量体とを併用して共重合体を形成すること、のいずれも可能である。 The (meth)acrylic acid ester monomers may be used alone or in combination of two or more kinds.
For example, it is possible to form a copolymer using a styrene monomer and two or more acrylate monomers, to form a copolymer using a styrene monomer and two or more methacrylate monomers, or to form a copolymer using a styrene monomer in combination with an acrylate monomer and a methacrylate monomer.
　上記スチレン・アクリル樹脂の重量平均分子量（Ｍｗ）は、可塑性を制御できる観点から、５０００～１５００００の範囲内であることが好ましく、３００００～１２００００の範囲内であることがより好ましい。なお、重量平均分子量（Ｍｗ）は、前述の（メタ）アクリル系樹脂と同様の方法で測定できる。 The weight average molecular weight (Mw) of the styrene-acrylic resin is preferably within the range of 5,000 to 150,000, and more preferably within the range of 30,000 to 120,000, from the viewpoint of being able to control the plasticity. The weight average molecular weight (Mw) can be measured in the same manner as for the (meth)acrylic resin described above.
　スチレン・アクリル樹脂は、市販品であっても良く、例えば、「ＴＸ３２０ＸＬ」（デンカ株式会社製、ＭＳ樹脂）が挙げられる。 The styrene-acrylic resin may be a commercially available product, for example, "TX320XL" (MS resin, manufactured by Denka Co., Ltd.).
　（１．１．１．３）シクロオレフィン系樹脂
　シクロオレフィン系樹脂は、シクロオレフィン単量体の重合体、又はシクロオレフィン単量体と共重合可能な他の単量体との共重合体であることが好ましい。 (1.1.1.3) Cycloolefin Resin The cycloolefin resin is preferably a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and another monomer copolymerizable with the cycloolefin monomer.
　シクロオレフィン単量体としては、ノルボルネン骨格を有するシクロオレフィン単量体であることが好ましい。中でも、下記一般式（Ａ－１）又は（Ａ－２）で表される構造を有するシクロオレフィン単量体であることがより好ましい。 The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton. Among them, a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferable.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
　上記一般式（Ａ－１）中、Ｒ１～Ｒ４は、それぞれ独立して、水素原子、炭素数１～３０の炭化水素基、又は極性基を表す。ｐは、０～２の整数を表す。ただし、Ｒ１～Ｒ４の
全てが同時に水素原子を表すことはなく、Ｒ１とＲ２が同時に水素原子を表すことはなく、Ｒ３とＲ４が同時に水素原子を表すことはないものとする。 In the above general formula (A-1), R 1 to R 4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. p represents an integer of 0 to 2. However, R 1 to R 4 do not all represent hydrogen atoms at the same time, R 1 and R 2 do not both represent hydrogen atoms, and R 3 and R 4 do not both represent hydrogen atoms.
　上記一般式（Ａ－１）において、Ｒ１～Ｒ４で表される炭素数１～３０の炭化水素基としては、例えば、炭素数１～１０の炭化水素基であることが好ましく、炭素数１～５の炭化水素基であることがより好ましい。炭素数１～３０の炭化水素基は、例えば、ハロゲン原子、酸素原子、窒素原子、硫黄原子、又はケイ素原子を含む連結基をさらに有していてもよい。そのような連結基としては、例えば、カルボニル基、イミノ基、エーテル結合、シリルエーテル結合、チオエーテル結合等の２価の極性基が挙げられる。炭素数１～３０の炭化水素基としては、例えば、メチル基、エチル基、プロピル基、ブチル基等が挙げられる。 In the above general formula (A-1), the hydrocarbon group having 1 to 30 carbon atoms represented by R 1 to R 4 is, for example, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Examples of such linking groups include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.
　上記一般式（Ａ－１）において、Ｒ１～Ｒ４で表される極性基としては、例えば、カルボキシ基、ヒドロキシ基、アルコキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アミノ基、アミド基、シアノ基等が挙げられる。中でも、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、又はアリールオキシカルボニル基であることが好ましい。溶液製膜時の溶解性の観点から、アルコキシカルボニル基又はアリールオキシカルボニル基であることが好ましい。 In the above general formula (A-1), examples of the polar group represented by R 1 to R 4 include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, and a cyano group. Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group is preferable. From the viewpoint of solubility during solution casting, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable.
　上記一般式（Ａ－１）におけるｐは、耐熱性を高める観点から、１又は２であることが好ましい。ｐが１又は２であることにより、得られる重合体が嵩高くなり、ガラス転移温度が向上しやすい。また、湿度に対して若干応答できるようになり、積層体とした場合のカールバランスを制御しやすくなる。 In the above general formula (A-1), p is preferably 1 or 2 from the viewpoint of increasing heat resistance. When p is 1 or 2, the resulting polymer becomes bulky and the glass transition temperature is likely to be improved. In addition, it becomes somewhat responsive to humidity, making it easier to control the curl balance when formed into a laminate.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　上記一般式（Ａ－２）中、Ｒ５は、水素原子、炭素数１～５の炭化水素基、又は炭素数１～５のアルキル基を有するアルキルシリル基を表す。Ｒ６は、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アミノ基、アミド基、シアノ基、又はハロゲン原子（フッ素原子、塩素原子、臭素原子、又はヨウ素原子）を表す。ｐは、０～２の整数を表す。 In the above general formula (A-2), R5 represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. R6 represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). p represents an integer of 0 to 2.
　上記一般式（Ａ－２）におけるＲ５は、炭素数１～５の炭化水素基であることが好ましく、炭素数１～３の炭化水素基であることがより好ましい。 R 5 in the above general formula (A-2) is preferably a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.
　上記一般式（Ａ－２）におけるＲ６は、カルボキシ基、ヒドロキシ基、アルコキシカルボニル基、又はアリールオキシカルボニル基であることが好ましく、溶液製膜時の溶解性の観点から、アルコキシカルボニル基又はアリールオキシカルボニル基であることがより好ましい。 In the above general formula (A-2), R 6 is preferably a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group, and from the viewpoint of solubility during solution casting, is more preferably an alkoxycarbonyl group or an aryloxycarbonyl group.
　上記一般式（Ａ－２）におけるｐは、耐熱性を高める観点から、１又は２であることが好ましい。ｐが１又は２であることにより、得られる重合体が嵩高くなり、ガラス転移温度が向上しやすい。 In order to improve heat resistance, p in the above general formula (A-2) is preferably 1 or 2. When p is 1 or 2, the resulting polymer becomes bulky and the glass transition temperature is easily improved.
　シクロオレフィン単量体としては、有機溶媒への溶解性が向上する観点から、上記一般式（Ａ－２）で表される構造を有するシクロオレフィン単量体であることが好ましい。一般的に、有機化合物は対称性を崩すことによって結晶性が低下するため、有機溶媒への溶解性が向上する。一般式（Ａ－２）におけるＲ５及びＲ６は、分子の対称軸に対して、環を構成する炭素原子の片側のみに置換されているため、分子の対称性が低い。すなわち、一般式（Ａ－２）で表される構造を有するシクロオレフィン単量体は、溶解性が高いため、光学フィルムを溶液流延法によって作製する場合に適している。 From the viewpoint of improving the solubility in an organic solvent, the cycloolefin monomer is preferably a cycloolefin monomer having the structure represented by the above general formula (A-2). In general, the crystallinity of an organic compound is reduced by breaking the symmetry, and the solubility in an organic solvent is improved. R 5 and R 6 in general formula (A-2) are substituted on only one side of the carbon atoms constituting the ring with respect to the symmetric axis of the molecule, and therefore the symmetry of the molecule is low. That is, the cycloolefin monomer having the structure represented by general formula (A-2) is highly soluble and is therefore suitable for producing an optical film by a solution casting method.
　シクロオレフィン系樹脂における一般式（Ａ－２）で表される構造を有するシクロオレフィン単量体の含有割合は、シクロオレフィン系樹脂を構成する全シクロオレフィン単量体の全モル数に対して、７０モル％以上であることが好ましい。また、８０モル％以上であることがより好ましく、１００モル％であることが更に好ましい。一般式（Ａ－２）で表される構造を有するシクロオレフィン単量体の含有割合が７０モル％以上であることにより、シクロオレフィン系樹脂の配向性が高まるため、位相差（リターデーション）値が上昇しやすい。 The content of the cycloolefin monomer having the structure represented by general formula (A-2) in the cycloolefin resin is preferably 70 mol% or more relative to the total number of moles of all cycloolefin monomers constituting the cycloolefin resin. Also, it is more preferable that it is 80 mol% or more, and even more preferable that it is 100 mol%. When the content of the cycloolefin monomer having the structure represented by general formula (A-2) is 70 mol% or more, the orientation of the cycloolefin resin is increased, and the phase difference (retardation) value is likely to increase.
　以下、一般式（Ａ－１）で表される構造を有するシクロオレフィン単量体の具体例を例示化合物１～１４に示す。また、一般式（Ａ－２）で表される構造を有するシクロオレフィン単量体の具体例を例示化合物１５～３４に示す。 Below, specific examples of cycloolefin monomers having a structure represented by general formula (A-1) are shown as example compounds 1 to 14. Also, specific examples of cycloolefin monomers having a structure represented by general formula (A-2) are shown as example compounds 15 to 34.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　シクロオレフィン単量体と共重合可能な共重合性単量体としては、例えば、シクロオレフィン単量体と開環共重合可能な共重合性単量体、シクロオレフィン単量体と付加共重合可能な共重合性単量体等が挙げられる。 Examples of copolymerizable monomers that can be copolymerized with cycloolefin monomers include copolymerizable monomers that can be ring-opening copolymerized with cycloolefin monomers, and copolymerizable monomers that can be addition copolymerized with cycloolefin monomers.
　開環共重合可能な共重合性単量体としては、例えば、シクロブテン、シクロペンテン、シクロヘプテン、シクロオクテン、ジシクロペンタジエン等のシクロオレフィンが挙げられる。 Examples of copolymerizable monomers capable of ring-opening copolymerization include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.
　付加共重合可能な共重合性単量体としては、例えば、不飽和二重結合含有化合物、ビニル系環状炭化水素単量体、（メタ）アクリレート等が挙げられる。不飽和二重結合含有化合物としては、炭素数２～１２（好ましくは２～８）のオレフィン系化合物が挙げられ、例えば、エチレン、プロピレン、ブテン等が挙げられる。ビニル系環状炭化水素単量体としては、４－ビニルシクロペンテン、２－メチル－４－イソプロペニルシクロペンテン等のビニルシクロペンテン系単量体が挙げられる。（メタ）アクリレートとしては、例えば、メチル（メタ）アクリレート、２－エチルヘキシル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート等の炭素数１～２０のアルキル（メタ）アクリレートが挙げられる。 Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, (meth)acrylates, etc. Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 carbon atoms (preferably 2 to 8), such as ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.
　シクロオレフィン単量体と共重合性単量体との共重合体におけるシクロオレフィン単量体の含有割合は、共重合体を構成する全単量体の合計に対して、２０～８０モル％の範囲内であることが好ましく、３０～７０モル％の範囲内であることが好ましい。 The content of the cycloolefin monomer in a copolymer of a cycloolefin monomer and a copolymerizable monomer is preferably within the range of 20 to 80 mol %, and more preferably within the range of 30 to 70 mol %, based on the total of all monomers constituting the copolymer.
　シクロオレフィン系樹脂は、前述のとおり、ノルボルネン骨格を有するシクロオレフィン単量体、好ましくは上記一般式（Ａ－１）又は（Ａ－２）で表される構造を有するシクロオレフィン単量体を、単独重合又は共重合して得られる重合体である。このような重合体としては、以下のものが挙げられる。
　１）シクロオレフィン単量体の開環重合体
　２）シクロオレフィン単量体と、それと開環共重合可能な共重合性単量体との開環共重合体
　３）上記１）又は２）の開環（共）重合体の水素添加物
　４）上記１）又は２）の開環（共）重合体をフリーデルクラフツ反応により環化した後、水素添加した（共）重合体
　５）シクロオレフィン単量体と、不飽和二重結合含有化合物との飽和共重合体
　６）シクロオレフィン単量体のビニル系環状炭化水素単量体との付加共重合体及びその水素添加物
　７）シクロオレフィン単量体と、（メタ）アクリレートとの交互共重合体 As described above, the cycloolefin resin is a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the above general formula (A-1) or (A-2). Examples of such polymers include the following.
1) Ring-opening polymer of cycloolefin monomer; 2) Ring-opening copolymer of cycloolefin monomer and a copolymerizable monomer capable of ring-opening copolymerization therewith; 3) Hydrogenated product of ring-opening (co)polymer of 1) or 2) above; 4) (co)polymer obtained by cyclizing ring-opening (co)polymer of 1) or 2) above by Friedel-Crafts reaction and then hydrogenating it; 5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound; 6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof; 7) Alternating copolymer of cycloolefin monomer and (meth)acrylate.
　上記１）～７）の重合体は、いずれも公知の方法、例えば、特開２００８－１０７５３４号公報や特開２００５－２２７６０６号公報に記載の方法で得ることができる。例えば、上記２）の開環共重合に用いられる触媒や溶媒は、例えば、特開２００８－１０７５３４号公報の段落００１９～００２４に記載のものを使用できる。上記３）及び６）の水素添加に用いられる触媒は、例えば、特開２００８－１０７５３４号公報の段落００２５～００２８に記載のものを使用できる。上記４）のフリーデルクラフツ反応に用いられる酸性化合物は、例えば、特開２００８－１０７５３４号公報の段落００２９に記載のものを使用できる。上記５）～７）の付加重合に用いられる触媒は、例えば、特開２００５－２２７６０６号公報の段落００５８～００６３に記載のものを使用できる。上記７）の交互共重合反応は、例えば、特開２００５－２２７６０６号公報の段落００７１～００７２に記載の方法で行うことができる。 The polymers 1) to 7) above can all be obtained by known methods, for example, the methods described in JP-A-2008-107534 and JP-A-2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization 2) above can be, for example, those described in paragraphs 0019 to 0024 of JP-A-2008-107534. The catalyst used in the hydrogenation 3) and 6) above can be, for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534. The acidic compound used in the Friedel-Crafts reaction 4) above can be, for example, those described in paragraph 0029 of JP-A-2008-107534. The catalyst used in the addition polymerization 5) to 7) above can be, for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606. The alternating copolymerization reaction of 7) above can be carried out, for example, by the method described in paragraphs 0071 to 0072 of JP 2005-227606 A.
　中でも、上記１）～３）又は５）の重合体であることが好ましく、上記３）又は５）の重合体であることがより好ましい。すなわち、得られる樹脂のガラス転移温度を高くし、かつ光透過率を高くできる観点から、当該シクロオレフィン系樹脂は、下記一般式（Ｂ－１）で表される構造単位と下記一般式（Ｂ－２）で表される構造単位の少なくとも一方を含むことが好ましい。そして、一般式（Ｂ－２）で表される構造単位のみを含む、又は一般式（Ｂ－１）で表される構造単位と一般式（Ｂ－２）で表される構造単位の両方を含むことがより好ましい。一般式（Ｂ－１）で表される構造単位は、前述の一般式（Ａ－１）で表されるシクロオレフィン単量体由来の構造単位であり、一般式（Ｂ－２）で表される構造単位は、前述の一般式（Ａ－２）で表されるシクロオレフィン単量体由来の構造単位である。 Among them, the polymers of 1) to 3) or 5) above are preferred, and the polymers of 3) or 5) above are more preferred. That is, from the viewpoint of increasing the glass transition temperature and light transmittance of the resulting resin, the cycloolefin resin preferably contains at least one of a structural unit represented by the following general formula (B-1) and a structural unit represented by the following general formula (B-2). It is more preferred that the cycloolefin resin contains only a structural unit represented by general formula (B-2), or contains both a structural unit represented by general formula (B-1) and a structural unit represented by general formula (B-2). The structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
　上記一般式（Ｂ－１）中、Ｘは、－ＣＨ＝ＣＨ－又は－ＣＨ２ＣＨ２－を表す。Ｒ１～Ｒ４及びｐは、それぞれ上記一般式（Ａ－１）のＲ１～Ｒ４及びｐと同義である。 In the above general formula (B-1), X represents -CH=CH- or -CH 2 CH 2 -, and R 1 to R 4 and p have the same meanings as R 1 to R 4 and p in the above general formula (A-1), respectively.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
　上記一般式（Ｂ－２）中、Ｘは、－ＣＨ＝ＣＨ－又は－ＣＨ２ＣＨ２－を表す。Ｒ５～Ｒ６及びｐは、それぞれ一般式（Ａ－２）のＲ５～Ｒ６及びｐと同義である。 In the above general formula (B-2), X represents -CH=CH- or -CH 2 CH 2 -, and R 5 to R 6 and p have the same meanings as R 5 to R 6 and p in general formula (A-2), respectively.
　本発明に用いられるシクロオレフィン系樹脂は、市販品であってもよい。シクロオレフィン系樹脂の市販品としては、例えば、ＪＳＲ株式会社製のアートン（ＡＲＴＯＮ（登録商標、以下同じ））Ｇ（例えば、Ｇ７８１０等）、アートンＦ、アートンＲ（例えば、Ｒ４５００、Ｒ４９００、Ｒ５０００等）、及びアートンＲＸ（例えば、ＲＸ４５００等）が挙げられる。 The cycloolefin resin used in the present invention may be a commercially available product. Examples of commercially available cycloolefin resins include ARTON (registered trademark, the same applies below) G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900, R5000, etc.), and ARTON RX (e.g., RX4500, etc.), all manufactured by JSR Corporation.
　シクロオレフィン系樹脂の３０℃における固有粘度〔η〕ｉｎｈは、０．２～５ｃｍ３／ｇの範囲内であることが好ましく、０．３～３ｃｍ３／ｇの範囲内であることがより好ましく、０．４～１．５ｃｍ３／ｇの範囲内であることが更に好ましい。 The intrinsic viscosity [η]inh of the cycloolefin resin at 30° C. is preferably within the range of 0.2 to 5 cm 3 /g, more preferably within the range of 0.3 to 3 cm 3 /g, and even more preferably within the range of 0.4 to 1.5 cm 3 /g.
　シクロオレフィン系樹脂の数平均分子量（Ｍｎ）は、８，０００～１０万の範囲内であることが好ましく、１００００～８００００の範囲内であることがより好ましく、１２０００～５００００の範囲内であることが更に好ましい。
　シクロオレフィン系樹脂の重量平均分子量（Ｍｗ）は、２００００～３０００００の範囲内であることが好ましく、３００００～２５００００の範囲内であることがより好ましく、４００００～２０００００の範囲内であることが更に好ましい。重量平均分子量（Ｍｗ）は、前述の（メタ）アクリル系樹脂と同様の方法で測定できる。 The number average molecular weight (Mn) of the cycloolefin resin is preferably within the range of 8,000 to 100,000, more preferably within the range of 10,000 to 80,000, and further preferably within the range of 12,000 to 50,000.
The weight average molecular weight (Mw) of the cycloolefin resin is preferably within a range of 20,000 to 300,000, more preferably within a range of 30,000 to 250,000, and further preferably within a range of 40,000 to 200,000. The weight average molecular weight (Mw) can be measured by the same method as that for the (meth)acrylic resin described above.
　固有粘度〔η〕ｉｎｈ、数平均分子量及び重量平均分子量（Ｍｗ）が、上記範囲内であることにより、シクロオレフィン系樹脂の耐熱性、耐水性、耐薬品性、機械的特性、及び光学フィルムとしての成形加工性が良好となる。 By having the intrinsic viscosity [η]inh, number average molecular weight, and weight average molecular weight (Mw) within the above ranges, the cycloolefin resin has good heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as an optical film.
　シクロオレフィン系樹脂のガラス転移温度（Ｔｇ）は、通常、１１０℃以上であり、１１０～３５０℃の範囲内であることが好ましく、１２０～２５０℃の範囲内であることがより好ましく、１２０～２２０℃の範囲内であることが更に好ましい。Ｔｇが、１１０℃以上であることにより、高温条件下での変形を抑制できる。一方、Ｔｇが、３５０℃以下であることにより、成形加工が容易となり、成形加工時の熱による樹脂の劣化を抑制できる。 The glass transition temperature (Tg) of cycloolefin resins is usually 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C. Having a Tg of 110°C or higher makes it possible to suppress deformation under high temperature conditions. On the other hand, having a Tg of 350°C or lower makes molding easier and suppresses deterioration of the resin due to heat during molding processing.
　シクロオレフィン系樹脂の含有量は、光学フィルムの全質量に対して、７０質量％以上であることが好ましく、８０質量％以上であることがより好ましい。 The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total mass of the optical film.
　（１．１．１．４）ポリイミド
　ポリイミドは、テトラカルボン酸二無水物とジアミンとの重合反応により合成される。 (1.1.1.4) Polyimide Polyimide is synthesized by a polymerization reaction between a tetracarboxylic dianhydride and a diamine.
　テトラカルボン酸二無水物としては、芳香族テトラカルボン酸二無水物、脂肪族テトラカルボン酸二無水物及び脂環式テトラカルボン酸二無水物が挙げられる。中でも、芳香族テトラカルボン酸二無水物であることが好ましい。
　ジアミンとしては、芳香族ジアミン、脂肪族ジアミン及び脂環式ジアミンが挙げられ、中でも、芳香族ジアミンであることが好ましい。 Examples of the tetracarboxylic dianhydride include aromatic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and alicyclic tetracarboxylic dianhydrides. Among these, aromatic tetracarboxylic dianhydrides are preferred.
The diamine may be an aromatic diamine, an aliphatic diamine, or an alicyclic diamine, and among these, an aromatic diamine is preferred.
　ポリイミドの重量平均分子量（Ｍｗ）は、１０万～３０万の範囲内であることが好ましく、１３万～２５万の範囲内であることがより好ましい。上記範囲内であることにより、光学フィルムの搬送時における搬送張力によって、光学フィルムが破断するのを抑制できる。重量平均分子量（Ｍｗ）は、前述の（メタ）アクリル系樹脂と同様の方法で測定できる。 The weight average molecular weight (Mw) of the polyimide is preferably within the range of 100,000 to 300,000, and more preferably within the range of 130,000 to 250,000. By being within the above range, it is possible to prevent the optical film from breaking due to the transport tension during transport. The weight average molecular weight (Mw) can be measured in the same manner as for the (meth)acrylic resin described above.
　ポリイミドの含有量は、光学フィルムの全質量に対して、６０質量％以上であることが好ましく、７０質量％以上であることがより好ましい。 The polyimide content is preferably 60% by mass or more, and more preferably 70% by mass or more, based on the total mass of the optical film.
　（１．１．１．５）セルロースエステル
　セルロースは、β－グルコースが、β－１，４－グリコシド結合により直鎖状につながった高分子である。そして、セルロースエステルは、１グルコース単位中の２位、３位及び６位のヒドロキシ基（－ＯＨ）のうち一部又は全部の水素原子が、アシル基で置換されたセルロースである。 (1.1.1.5) Cellulose ester Cellulose is a polymer in which β-glucose units are linked in a linear chain via β-1,4-glycosidic bonds. Cellulose ester is cellulose in which some or all of the hydrogen atoms in the hydroxyl groups (-OH) at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups.
　セルロースエステルは、特に制限されないが、炭素数２～２２程度の直鎖又は分岐のカルボン酸のエステルであることが好ましい。
　エステルを構成するカルボン酸としては、脂肪族カルボン酸、脂環式カルボン酸、芳香族カルボン酸が挙げられる。 The cellulose ester is not particularly limited, but is preferably an ester of a linear or branched carboxylic acid having about 2 to 22 carbon atoms.
Examples of the carboxylic acid constituting the ester include an aliphatic carboxylic acid, an alicyclic carboxylic acid, and an aromatic carboxylic acid.
　セルロースエステルの置換されたアシル基としては、アセチル基、プロピオニル基、ブチリル基、イソブチリル基、バレリル基、ピバロイル基、ヘキサノイル基、オクタノイル基、ラウロイル基、ステアロイル等の炭素数２～２２のアシル基が挙げられる。 Examples of the substituted acyl groups of cellulose esters include acyl groups having 2 to 22 carbon atoms, such as acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, and stearoyl.
　エステルを構成するカルボン酸（アシル基）は、置換基を有してもよい。
　エステルを構成するカルボン酸は、特に炭素数が６以下の低級脂肪酸であることが好ましく、炭素数が３以下の低級脂肪酸であることがより好ましい。 The carboxylic acid (acyl group) constituting the ester may have a substituent.
The carboxylic acid constituting the ester is preferably a lower fatty acid having 6 or less carbon atoms, more preferably a lower fatty acid having 3 or less carbon atoms.
　なお、セルロースエステル中のアシル基は単一種であってもよいし、複数のアシル基の組み合わせであってもよい。 The acyl group in the cellulose ester may be of a single type or a combination of multiple acyl groups.
　セルロースエステルの具体例としては、ジアセチルセルロース（ＤＡＣ）、トリアセチルセルロース（ＴＡＣ）等のセルロースアセテートが挙げられる。また、セルロースアセテートプロピオネート（ＣＡＰ）、セルロースアセテートブチレート、セルロースアセテートプロピオネートブチレート等のアセチル基の他にプロピオネート基又はブチレート基が結合したセルロースの混合脂肪酸エステルが挙げられる。
　セルロースエステルは、一種単独で用いても、二種以上併用してもよい。 Specific examples of cellulose esters include cellulose acetates such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), as well as mixed fatty acid esters of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group, such as cellulose acetate propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate.
The cellulose esters may be used alone or in combination of two or more.
　＜アシル基の種類・置換度＞
　セルロースエステルのアシル基の種類及び置換度を適宜選択することによって、光学フィルムにおける位相差の湿度変動を、所望の範囲内に制御することができる。その結果、光学フィルムの厚さの均一性を向上できる。 <Type and degree of substitution of acyl group>
By appropriately selecting the type and substitution degree of the acyl group of the cellulose ester, the humidity change of the retardation of the optical film can be controlled within a desired range, and as a result, the thickness uniformity of the optical film can be improved.
　アシル基の置換度は、１グルコース単位あたりのアシル基の平均数を表す。つまり、１グルコース単位中の２位、３位及び６位のヒドロキシ基の水素原子のうち、いくつの水素原子がアシル基に置換されているかを表す。
　したがって、アシル基の置換度の最大値は３．０であり、この場合、２位、３位及び６位のヒドロキシ基の水素原子全てが、アシル基で置換されていることを意味する。 The degree of acyl substitution represents the average number of acyl groups per glucose unit, i.e., how many of the hydrogen atoms of the hydroxyl groups at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups.
Therefore, the maximum degree of substitution of the acyl group is 3.0, which means that all of the hydrogen atoms of the hydroxy groups at the 2-, 3- and 6-positions are substituted with acyl groups.
　アシル基は、１グルコース単位中の２位、３位及び６位に平均的に置換していてもよいし、分布をもって置換していてもよい。
　アシル基の置換度は、ＡＳＴＭ－Ｄ８１７－９６に規定の方法により求められる。 The acyl groups may be substituted evenly at the 2-, 3- and 6-positions of one glucose unit, or may be substituted with a distribution.
The degree of acyl substitution can be determined by the method specified in ASTM-D817-96.
　セルロースエステルのアシル基の置換度が大きすぎると、位相差が発現しにくくなるため、光学フィルムを作製する際に延伸倍率を増加させる必要がある。ただし、高延伸倍率で均一に延伸させることは難しく、光学フィルムの厚さのバラつきが大きくなりやすい。一方、セルロースエステルのアシル基の置換度を小さくするほど、位相差が発現しやすくなるため、光学フィルムの厚さを薄く、均一にできる。
　しかしながら、セルロースエステルのアシル基の置換度が小さすぎると、光学フィルムの耐久性が低下するため、耐久性の観点からは、置換度を小さくしすぎないことが好ましい。 If the substitution degree of the acyl group of the cellulose ester is too large, the retardation is difficult to be expressed, so that it is necessary to increase the stretching ratio when producing the optical film. However, it is difficult to uniformly stretch at a high stretching ratio, and the thickness of the optical film tends to vary greatly. On the other hand, the smaller the substitution degree of the acyl group of the cellulose ester, the easier it is to express the retardation, so that the thickness of the optical film can be made thin and uniform.
However, if the degree of substitution of the acyl group in the cellulose ester is too small, the durability of the optical film decreases, and therefore, from the viewpoint of durability, it is preferable not to make the degree of substitution too small.
　厚さ方向のリターデーション（Ｒｔ、位相差）の湿度による変動は、セルロースのカルボニル基に水分子が配位することで生じる。このため、アシル基の置換度を小さく、すなわち、セルロース中のカルボニル基を少なくするほど、Ｒｔの湿度による変動を生じにくくできる。 The humidity-dependent change in retardation (Rt, phase difference) in the thickness direction occurs when water molecules coordinate with the carbonyl groups of cellulose. Therefore, the smaller the degree of acyl group substitution, i.e., the fewer the carbonyl groups in the cellulose, the less humidity-dependent change in Rt occurs.
　セルロースエステルのアシル基の置換度は、２．１～２．５の範囲内であることが好ましく、２．２～２．４５の範囲内であることが好ましい。
　上記範囲内であることにより、環境変動（特に、Ｒｔの湿度による変動）を抑制するとともに、光学フィルムの厚さの均一性を向上できる。また、光学フィルムの作製時の流延性及び延伸性を向上できる。 The degree of substitution of the acyl group in the cellulose ester is preferably within a range of 2.1 to 2.5, and more preferably within a range of 2.2 to 2.45.
By being in the above range, environmental fluctuations (particularly fluctuations in Rt due to humidity) can be suppressed, and the uniformity of the thickness of the optical film can be improved. In addition, the flowability and stretchability during production of the optical film can be improved.
　また、セルロースエステルのアシル基の置換度は、下記式（ａ）及び（ｂ）を共に満たすことが好ましい。ただし、下記式（ａ）及び（ｂ）中、Ｘはアセチル基の置換度、Ｙはプロピオニル基又はブチリル基の置換度、若しくはその混合物の置換度である。 In addition, it is preferable that the degree of substitution of the acyl group of the cellulose ester satisfies both of the following formulas (a) and (b). In the following formulas (a) and (b), X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or the butyryl group, or the degree of substitution of a mixture thereof.
　式（ａ）：　２．１≦Ｘ＋Ｙ≦２．５
　式（ｂ）：　０≦Ｙ≦１．５ Formula (a): 2.1≦X+Y≦2.5
Formula (b): 0≦Y≦1.5
　セルロースエステルは、セルロースアセテート（Ｙ＝０）、又はセルロースアセテートプロピオネート（ＣＡＰ）（Ｙ；プロピオニル基、Ｙ＞０）であることが好ましい。中でも、光学フィルムの厚さの均一性の観点から、Ｙ＝０であるセルロースアセテートであることが好ましい。 The cellulose ester is preferably cellulose acetate (Y=0) or cellulose acetate propionate (CAP) (Y: propionyl group, Y>0). Of these, cellulose acetate with Y=0 is preferred from the viewpoint of uniformity of the thickness of the optical film.
　セルロースアセテートのアセチル基の置換度Ｘは、位相差の発現性、Ｒｔの湿度による変動、光学フィルムの均一性の観点から、２．１≦Ｘ≦２．５、を満たすことが好ましく、２．１５≦Ｘ≦２．４５、を満たすことがより好ましい。上記範囲内を満たすセルロースアセテートとしては、セルロースジアセテート（ＤＡＣ）が挙げられる。 From the viewpoints of retardation expression, Rt variation due to humidity, and uniformity of the optical film, the degree of substitution X of the acetyl group of cellulose acetate preferably satisfies 2.1≦X≦2.5, and more preferably satisfies 2.15≦X≦2.45. An example of cellulose acetate that satisfies the above range is cellulose diacetate (DAC).
　また、Ｙ＞０の場合、セルロースエステルは、セルロースアセテートプロピオネート（ＣＡＰ）であることが好ましい。このとき、Ｘ及びＹは、０．９５≦Ｘ≦２．２５、０．１≦Ｙ≦１．２、２．１５≦Ｘ＋Ｙ≦２．４５、のいずれも満たすことが好ましい。 In addition, when Y>0, the cellulose ester is preferably cellulose acetate propionate (CAP). In this case, it is preferable that X and Y satisfy any of the following: 0.95≦X≦2.25, 0.1≦Y≦1.2, 2.15≦X+Y≦2.45.
　これらの条件を満たすセルロースアセテート又はセルロースアセテートプロピオネートを用いることにより、リターデーション、機械的強度、環境変動に優れた光学フィルムが得られる。 By using cellulose acetate or cellulose acetate propionate that meets these conditions, an optical film with excellent retardation, mechanical strength, and resistance to environmental changes can be obtained.
　また、所望の光学特性を得るために、置換度の異なるセルロースアセテートを混合して用いてもよい。異なるセルロースアセテートの混合比率は、特に制限されない。 Also, to obtain the desired optical properties, cellulose acetates with different degrees of substitution may be mixed. There are no particular limitations on the mixing ratio of the different cellulose acetates.
　機械的強度の観点から、セルロースエステルの数平均分子量（Ｍｎ）は、２×１０４～３×１０５の範囲内であることが好ましく、２×１０４～１．２×１０５の範囲内であることがより好ましく、４×１０４～８×１０４の範囲内であることが更に好ましい。 From the viewpoint of mechanical strength, the number average molecular weight (Mn) of the cellulose ester is preferably within the range of 2×10 4 to 3×10 5 , more preferably within the range of 2×10 4 to 1.2×10 5 , and even more preferably within the range of 4×10 4 to 8×10 4 .
　セルロースエステルの数平均分子量（Ｍｎ）は、前述の（メタ）アクリル系樹脂と同様の方法で測定できる。 The number average molecular weight (Mn) of cellulose ester can be measured in the same manner as for the (meth)acrylic resin described above.
　機械的強度の観点から、セルロースエステルの重量平均分子量（Ｍｗ）は、２×１０４～１×１０６の範囲内であることが好ましく、２×１０４～１．２×１０５の範囲内であることがより好ましく、４×１０４～８×１０４の範囲内であることが更に好ましい。 From the viewpoint of mechanical strength, the weight average molecular weight (Mw) of the cellulose ester is preferably within the range of 2×10 4 to 1×10 6 , more preferably within the range of 2×10 4 to 1.2×10 5 , and even more preferably within the range of 4×10 4 to 8×10 4 .
　セルロースエステルの原料セルロースとしては、特に制限されないが、綿花リンター、木材パルプ、ケナフ等が挙げられる。また、これらから得られたセルロースエステルは、それぞれ任意の割合で混合して用いてもよい。 The raw cellulose for cellulose ester is not particularly limited, but examples include cotton linters, wood pulp, kenaf, etc. Furthermore, the cellulose esters obtained from these may be mixed in any desired ratio.
　セルロースアセテート、セルロースアセテートプロピオネート等のセルロースエステルは、公知の方法により合成できる。 Cellulose esters such as cellulose acetate and cellulose acetate propionate can be synthesized by known methods.
　一般的には、原料のセルロース、有機酸（酢酸、プロピオン酸等）、酸無水物（無水酢酸、無水プロピオン酸等）及び触媒（硫酸等）を混合して、セルロースをエステル化し、セルロースのトリエステルができるまで反応を進める。 Generally, the raw material cellulose, organic acid (acetic acid, propionic acid, etc.), acid anhydride (acetic anhydride, propionic anhydride, etc.) and catalyst (sulfuric acid, etc.) are mixed together to esterify the cellulose, and the reaction is allowed to proceed until a cellulose triester is produced.
　トリエステルにおいては、１グルコース単位中の３個のヒドロキシ基は、有機酸のアシル酸で置換されている。 In triesters, the three hydroxy groups in one glucose unit are replaced with an organic acyl acid.
　同時に二種類の有機酸を用いることにより、混合エステル型のセルロースエステル、例えばセルロースアセテートプロピオネートやセルロースアセテートブチレートを合成できる。 By using two types of organic acids at the same time, it is possible to synthesize mixed ester type cellulose esters, such as cellulose acetate propionate and cellulose acetate butyrate.
　次いで、セルロースのトリエステルを加水分解することで、所望のアシル置換度を有するセルロースエステルが得られる。
　その後、ろ過、沈殿、水洗、脱水、乾燥等の工程を経て、最終的にセルロースエステルが得られる。具体的には、特開平１０－４５８０４号に記載の方法を参考にして合成できる。 The cellulose triester is then hydrolyzed to give a cellulose ester having the desired degree of acyl substitution.
Thereafter, the cellulose ester is finally obtained through steps such as filtration, precipitation, washing, dehydration, drying, etc. Specifically, the cellulose ester can be synthesized by referring to the method described in JP-A-10-45804.
　（１．１．２）ゴム粒子
　本発明において、「ゴム粒子」とは、室温でゴム弾性を示す樹脂を含有する粒子のことをいう。 (1.1.2) Rubber Particles In the present invention, the term "rubber particles" refers to particles containing a resin that exhibits rubber elasticity at room temperature.
　本発明に係る光学フィルムは、ゴム粒子を含有することが好ましい。
　ゴム粒子を含有することにより、光学フィルムに靱性（しなやかさ）を付与できる。また、光学フィルムの貯蔵弾性率及び損失正接（ｔａｎδ）を適宜調整できる。その結果、ガラス層における耐衝撃性が良好である積層体が得られる。 The optical film according to the present invention preferably contains rubber particles.
By including the rubber particles, toughness (flexibility) can be imparted to the optical film. In addition, the storage modulus and loss tangent (tan δ) of the optical film can be appropriately adjusted. As a result, a laminate having good impact resistance in the glass layer can be obtained.
　中でも、光学フィルムＢがゴム粒子を含有することがより好ましい。光学フィルムＢがゴム粒子を含有することにより、光学フィルムＢの損失正接（ｔａｎδＢ）を適宜調整でき、耐衝撃性をより向上できる。 In particular, it is more preferable that the optical film B contains rubber particles. By containing rubber particles in the optical film B, the loss tangent (tan δ B ) of the optical film B can be appropriately adjusted, and the impact resistance can be further improved.
　本発明に係るゴム粒子の層構成は、単層構成であっても、多層構成であってもよい。また、室温でゴム弾性を示す樹脂（以下、「ゴム状重合体」ともいう。）としては、特に制限されない。モノマーの配列順序も特に制限されず、例えば、線状、櫛状（グラフト型）、分岐状（星型）のいずれであってもよい。
　ゴム状重合体は、架橋性のモノマーにより、一部架橋された構造であってもよい。 The layer structure of the rubber particles according to the present invention may be a single layer structure or a multi-layer structure. In addition, the resin exhibiting rubber elasticity at room temperature (hereinafter also referred to as "rubber-like polymer") is not particularly limited. The order of monomer arrangement is also not particularly limited, and may be, for example, linear, comb-like (graft type), or branched (star type).
The rubber-like polymer may have a structure that is partially crosslinked with a crosslinkable monomer.
　本発明において、ゴム状重合体は、室温でゴム弾性を示す観点から、ガラス転移温度（Ｔｇ）が０℃以下の軟質な架橋重合体であることが好ましい。
　このような架橋重合体としては、例えば、ブタジエン系架橋重合体、（メタ）アクリル系架橋重合体、オルガノシロキサン系架橋重合体等が挙げられる。中でも、熱可塑性（メタ）アクリル系樹脂との屈折率差が小さく、光学フィルムの透明性が損なわれにくい観点から、（メタ）アクリル系架橋重合体であることが好ましく、アクリル系架橋重合体であることがより好ましい。 In the present invention, the rubber-like polymer is preferably a soft crosslinked polymer having a glass transition temperature (Tg) of 0° C. or lower, from the viewpoint of exhibiting rubber elasticity at room temperature.
Examples of such crosslinked polymers include butadiene-based crosslinked polymers, (meth)acrylic crosslinked polymers, organosiloxane crosslinked polymers, etc. Among them, (meth)acrylic crosslinked polymers are preferred, and acrylic crosslinked polymers are more preferred, from the viewpoint of a small difference in refractive index from thermoplastic (meth)acrylic resins and less loss of transparency of the optical film.
　すなわち、本発明に係るゴム粒子は、アクリル系架橋重合体（以下、「アクリル系ゴム状重合体」ともいう。）を含有する粒子であることが好ましい。 In other words, the rubber particles according to the present invention are preferably particles containing an acrylic crosslinked polymer (hereinafter also referred to as an "acrylic rubber-like polymer").
　ゴム粒子の含有量は、光学フィルムの全質量に対して、１０～８０質量％の範囲内であることが好ましい。上記範囲内であることにより、光学フィルムが適度な硬さを有し、かつ光学フィルムが所望の貯蔵弾性率及び損失正接（ｔａｎδ）を得られる。 The content of rubber particles is preferably within the range of 10 to 80% by mass relative to the total mass of the optical film. By being within the above range, the optical film has an appropriate hardness and can obtain the desired storage modulus and loss tangent (tan δ).
　屈曲後のコントラストの観点から、本発明に係る光学フィルムＢは、少なくとも、（メタ）アクリル系樹脂とグラフト共重合体のゴム粒子との組み合わせを含有することが好ましい。 From the viewpoint of contrast after bending, it is preferable that optical film B according to the present invention contains at least a combination of a (meth)acrylic resin and rubber particles of a graft copolymer.
　（メタ）アクリル系樹脂及びゴム粒子を含有する光学フィルムとする場合、（メタ）アクリル系樹脂の含有量は、光学フィルムの全質量に対して、５～９５質量％の範囲内であることが好ましい。また、１０～６０質量％の範囲内であることがより好ましく、１０～５０質量％の範囲内であることが更に好ましく、１０～４０質量％の範囲内であることが特に好ましい。 When the optical film contains a (meth)acrylic resin and rubber particles, the content of the (meth)acrylic resin is preferably within the range of 5 to 95% by mass relative to the total mass of the optical film. It is more preferably within the range of 10 to 60% by mass, even more preferably within the range of 10 to 50% by mass, and particularly preferably within the range of 10 to 40% by mass.
　（メタ）アクリル系樹脂及びゴム粒子を含有する光学フィルムとする場合、ゴム粒子の含有量は、光学フィルムの全質量に対して、１０～８０質量％の範囲内であることが好ましい。また、２０～６０質量％の範囲内であることがより好ましく、２０～５０質量％の範囲内であることが更に好ましい。上記範囲内であることにより、凝集体の大きさが十分かつ均一なものとなり、フィルムに異物が混入しにくく、光学特性や機械特性が向上した光学フィルムが得られる。 When making an optical film containing a (meth)acrylic resin and rubber particles, the content of the rubber particles is preferably within the range of 10 to 80% by mass, based on the total mass of the optical film. Also, it is more preferable that it is within the range of 20 to 60% by mass, and even more preferable that it is within the range of 20 to 50% by mass. By being within the above range, the size of the aggregates becomes sufficient and uniform, foreign matter is less likely to be mixed into the film, and an optical film with improved optical properties and mechanical properties can be obtained.
　（１．１．２．１）ゴム粒子の構成材料
　前述のとおり、本発明に係るゴム粒子は、アクリル系ゴム状重合体を含有することが好ましい。以下、説明のため、アクリル系ゴム状重合体を、「アクリル系ゴム状重合体（ａ）」と表す。 (1.1.2.1) Constituent material of rubber particles As described above, the rubber particles according to the present invention preferably contain an acrylic rubber-like polymer. For the sake of explanation, the acrylic rubber-like polymer will be referred to as "acrylic rubber-like polymer (a)" below.
　アクリル系ゴム状重合体（ａ）は、アクリル酸エステルに由来する構造単位を主成分として有する架橋重合体である。
　ここで、「主成分として有する」とは、アクリル酸エステルに由来する構造単位の含有量が、後述する範囲内であることをいう。 The acrylic rubber-like polymer (a) is a crosslinked polymer having, as a main component, a structural unit derived from an acrylic ester.
Here, "having as a main component" means that the content of structural units derived from acrylic ester is within the range described below.
　アクリル系ゴム状重合体（ａ）は、アクリル酸エステルに由来する構造単位と、これと共重合可能な他の単量体に由来する構造単位と、１分子中に２個以上のラジカル重合性基（非共役な反応性二重結合）を有する多官能性単量体に由来する構造単位と、を有する架橋重合体であることが好ましい。 The acrylic rubber-like polymer (a) is preferably a crosslinked polymer having structural units derived from an acrylic acid ester, structural units derived from other monomers copolymerizable therewith, and structural units derived from a polyfunctional monomer having two or more radically polymerizable groups (non-conjugated reactive double bonds) in one molecule.
　アクリル酸エステルとしては、アクリル酸メチル（メチルアクリレート）、アクリル酸エチル（エチルアクリレート）、アクリル酸ｎ－プロピル（ｎ－プロピルアクリレート）、アクリル酸ｎ－ブチル（ｎ－ブチルアクリレート）、アクリル酸ｓｅｃ－ブチル（ｓｅｃ－ブチルアクリレート）、アクリル酸イソブチル（イソブチルアクリレート）、アクリル酸ベンジル（ベンジルアクリレート）、アクリル酸シクロヘキシル（シクロへキシルアクリレート）、アクリル酸２－エチルヘキシル（２－エチルへキシルアクリレート）、アクリル酸ｎ－オクチル（ｎ－オクチルアクリレート）等の、アルキル基の炭素数が１～１２のアクリル酸アルキルエステルであることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 The acrylic acid ester is preferably an alkyl acrylate having an alkyl group having 1 to 12 carbon atoms, such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), n-propyl acrylate (n-propyl acrylate), n-butyl acrylate (n-butyl acrylate), sec-butyl acrylate (sec-butyl acrylate), isobutyl acrylate (isobutyl acrylate), benzyl acrylate (benzyl acrylate), cyclohexyl acrylate (cyclohexyl acrylate), 2-ethylhexyl acrylate (2-ethylhexyl acrylate), or n-octyl acrylate (n-octyl acrylate).
These may be used alone or in combination of two or more.
　アクリル酸エステルに由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ）を構成する全構造単位に対して、４０～９０質量％の範囲内であることが好ましく、５０～８０質量％の範囲内であることがより好ましい。上記範囲内であることにより、光学フィルムに十分な靱性を付与できる。 The content of structural units derived from acrylic esters is preferably within the range of 40 to 90 mass % of all structural units constituting the acrylic rubber-like polymer (a), and more preferably within the range of 50 to 80 mass %. By being within the above range, sufficient toughness can be imparted to the optical film.
　アクリル酸エステルと共重合可能な他の単量体としては、メタクリル酸メチル等のメタクリル酸エステル；スチレン、メチルスチレン等のスチレン類；（メタ）アクリロニトリル類；（メタ）アクリルアミド類；（メタ）アクリル酸が挙げられる。中でも、スチレン類であることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of other monomers copolymerizable with acrylic acid esters include methacrylic acid esters such as methyl methacrylate, styrenes such as styrene and methylstyrene, (meth)acrylonitriles, (meth)acrylamides, and (meth)acrylic acid. Among these, styrenes are preferred.
These may be used alone or in combination of two or more.
　アクリル酸エステルと共重合可能な他の単量体に由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ）を構成する全構造単位に対して、５～５５質量％の範囲内であることが好ましく、１０～４５質量％の範囲内であることがより好ましい。 The content of structural units derived from other monomers copolymerizable with acrylic esters is preferably within the range of 5 to 55% by mass, and more preferably within the range of 10 to 45% by mass, based on the total structural units constituting the acrylic rubber-like polymer (a).
　１分子中に２個以上のラジカル重合性基を有する多官能性単量体としては、例えば、アリル（メタ）アクリレート、トリアリルシアヌレート、トリアリルイソシアヌレート、ジアリルフタレート、ジアリルマレート、ジビニルアジペート、ジビニルベンゼン、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（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、トリメチロールプロパントリ（メタ）アクリレート、テトロメチロールメタンテトラ（メタ）アクリレート、ジプロピレングリコールジ（メタ）アクリレート、ポリエチレングリコールジ（メタ）アクリレートが挙げられる。 Examples of polyfunctional monomers having two or more radically polymerizable groups in one molecule include allyl (meth)acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinyl benzene, ethylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipropylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate.
　１分子中に２個以上のラジカル重合性基を有する多官能性単量体に由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ）を構成する全構造単位に対して、０．０５～１０質量％の範囲内であることが好ましく、０．１～５質量％の範囲内であることがより好ましい。０．０５質量％以上であることにより、得られるアクリル系ゴム状重合体（ａ）の架橋度を高めやすく、光学フィルムの硬度、剛性が損なわれにくい。また、１０質量％以下であることにより、光学フィルムの靱性が損なわれにくい。 The content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.05 to 10 mass % of all structural units constituting the acrylic rubber-like polymer (a), and more preferably within the range of 0.1 to 5 mass %. By having a content of 0.05 mass % or more, it is easy to increase the degree of crosslinking of the obtained acrylic rubber-like polymer (a), and the hardness and rigidity of the optical film are less likely to be impaired. Furthermore, by having a content of 10 mass % or less, the toughness of the optical film is less likely to be impaired.
　アクリル系ゴム状重合体（ａ）を構成するモノマーの組成は、例えば、熱分解ＧＣ－ＭＳにより検出されるピーク面積比により測定できる。 The composition of the monomers constituting the acrylic rubber-like polymer (a) can be measured, for example, by the peak area ratio detected by pyrolysis GC-MS.
　アクリル系ゴム状重合体（ａ）のガラス転移温度（Ｔｇ）は、０℃以下であることが好ましく、－１０℃以下であることがより好ましい。０℃以下であることにより、光学フィルムに適度な靱性を付与できる。アクリル系ゴム状重合体（ａ）のガラス転移温度（Ｔｇ）は、前述と同様の方法で測定できる。 The glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is preferably 0°C or lower, and more preferably -10°C or lower. A glass transition temperature of 0°C or lower can impart appropriate toughness to the optical film. The glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be measured by the same method as described above.
　アクリル系ゴム状重合体（ａ）のガラス転移温度（Ｔｇ）は、アクリル系ゴム状重合体（ａ）の組成によって調整できる。例えば、ガラス転移温度（Ｔｇ）を低くするためには、アクリル酸エステルと共重合可能な他の単量体に対する、アルキル基の炭素数が４以上であるアクリル酸エステルの質量比の値を調整することが好ましい。なお、質量比は、アクリル酸エステルの質量／アクリル酸エステルと共重合可能な他の単量体の質量、で表される。質量比の値は、３以上であることが好ましく、４～１０の範囲内であることが好ましい。 The glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be adjusted by the composition of the acrylic rubber-like polymer (a). For example, in order to lower the glass transition temperature (Tg), it is preferable to adjust the mass ratio of the acrylic ester having an alkyl group with 4 or more carbon atoms to the other monomer copolymerizable with the acrylic ester. The mass ratio is expressed as the mass of the acrylic ester/the mass of the other monomer copolymerizable with the acrylic ester. The mass ratio is preferably 3 or more, and is preferably within the range of 4 to 10.
　アクリル系ゴム状重合体（ａ）を含有する粒子は、アクリル系ゴム状重合体（ａ）のみからなる粒子であってもよい。また、ガラス転移温度（Ｔｇ）が２０℃以上である硬質な架橋重合体（ｃ）からなる硬質層と、その周囲に配置されたアクリル系ゴム状重合体（ａ）からなる軟質層とを有する粒子であってもよい。その他、アクリル系ゴム状重合体（ａ）の存在下で、メタクリル酸エステルなどの単量体の混合物を、少なくとも一段以上重合して得られるアクリル系グラフト共重合体からなる粒子であってもよい。アクリル系グラフト共重合体からなる粒子は、アクリル系ゴム状重合体（ａ）を含むコア部と、それを覆うシェル部とを有するコアシェル型の粒子であってもよい。 The particles containing the acrylic rubber-like polymer (a) may be particles consisting of only the acrylic rubber-like polymer (a). They may also be particles having a hard layer consisting of a hard crosslinked polymer (c) having a glass transition temperature (Tg) of 20°C or higher, and a soft layer consisting of the acrylic rubber-like polymer (a) arranged around it. In addition, they may be particles consisting of an acrylic graft copolymer obtained by polymerizing a mixture of monomers such as methacrylic acid esters in at least one stage in the presence of the acrylic rubber-like polymer (a). The particles consisting of the acrylic graft copolymer may be core-shell type particles having a core containing the acrylic rubber-like polymer (a) and a shell covering the core.
　（コア部）
　コア部は、アクリル系ゴム状重合体（ａ）を含有し、必要に応じて硬質な架橋重合体（ｃ）を更に含有してもよい。すなわち、コア部は、アクリル系ゴム状重合体（ａ）からなる軟質層と、その内側に配置された硬質な架橋重合体（ｃ）からなる硬質層とを有してもよい。
　以下、説明のため、硬質な架橋重合体を、「架橋重合体（ｃ）」と表す。 (Core part)
The core contains an acrylic rubber-like polymer (a) and may further contain a hard crosslinked polymer (c) as necessary. That is, the core may have a soft layer made of the acrylic rubber-like polymer (a) and a hard layer made of the hard crosslinked polymer (c) disposed inside the soft layer.
For the sake of explanation, the rigid crosslinked polymer will be referred to as "crosslinked polymer (c)" hereinafter.
　架橋重合体（ｃ）は、メタクリル酸エステルを主成分とする架橋重合体である。すなわち、架橋重合体（ｃ）は、メタクリル酸エステルに由来する構造単位と、これと共重合可能な他の単量体に由来する構造単位と、１分子中に２個以上のラジカル重合性基を有する多官能性単量体に由来する構造単位と、を有する架橋重合体であることが好ましい。 The crosslinked polymer (c) is a crosslinked polymer containing a methacrylic acid ester as a main component. In other words, the crosslinked polymer (c) is preferably a crosslinked polymer having a structural unit derived from a methacrylic acid ester, a structural unit derived from another monomer copolymerizable therewith, and a structural unit derived from a polyfunctional monomer having two or more radically polymerizable groups in one molecule.
　メタクリル酸エステルは、メタクリル酸アルキルエステルであることが好ましい。メタクリル酸アルキルエステルとしては、前述のアクリル酸アルキルエステルにおいて、アルキル酸をメタクリル酸に置き換えたものが挙げられる。
　メタクリル酸エステルと共重合可能な他の単量体は、前述のアクリル酸エステルと共重合可能な他の単量体と同様のものが挙げられる。
　１分子中に２個以上のラジカル重合性基を有する多官能性単量体は、前述と同様のものが挙げられる。 The methacrylic acid ester is preferably an alkyl methacrylate ester, such as the above-mentioned alkyl acrylate ester in which the alkyl acid is replaced with methacrylic acid.
Examples of the other monomers copolymerizable with the methacrylic acid ester include the same monomers as those described above as the other monomers copolymerizable with the acrylic acid ester.
Examples of the polyfunctional monomer having two or more radically polymerizable groups in one molecule include the same as those mentioned above.
　メタクリル酸アルキルエステルに由来する構造単位の含有量は、架橋重合体（ｃ）を構成する全構造単位に対して、４０～１００質量％の範囲内であることが好ましい。メタクリル酸エステルと共重合可能な他の単量体に由来する構造単位の含有量は、架橋重合体（ｃ）を構成する全構造単位に対して、６０～０質量％の範囲内であることが好ましい。１分子中に２個以上のラジカル重合性基を有する多官能性単量体に由来する構造単位の含有量は、架橋重合体（ｃ）を構成する全構造単位に対して、０．０１～１０質量％の範囲内であることが好ましい。 The content of structural units derived from methacrylic acid alkyl esters is preferably within the range of 40 to 100% by mass relative to all structural units constituting the crosslinked polymer (c). The content of structural units derived from other monomers copolymerizable with methacrylic acid esters is preferably within the range of 60 to 0% by mass relative to all structural units constituting the crosslinked polymer (c). The content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.01 to 10% by mass relative to all structural units constituting the crosslinked polymer (c).
　（シェル部）
　シェル部は、アクリル系ゴム状重合体（ａ）にグラフト結合した、メタクリル酸エステルに由来する構造単位を主成分として有するメタクリル系重合体（ｂ）（他の重合体）を含有することが好ましい。
　以下、説明のため、メタクリル酸エステルに由来する構造単位を主成分として有するメタクリル系重合体を、「メタクリル系重合体（ｂ）」と表す。
　ここで、「主成分として有する」とは、メタクリル酸エステルに由来する構造単位の含有量が、後述する範囲内であることをいう。 (Shell part)
The shell portion preferably contains a methacrylic polymer (b) (another polymer) having as its main component a structural unit derived from a methacrylic acid ester, graft-bonded to the acrylic rubber-like polymer (a).
For the sake of explanation, a methacrylic polymer having a structural unit derived from a methacrylic acid ester as a main component will be referred to as a "methacrylic polymer (b)" hereinafter.
Here, "having as a main component" means that the content of the structural unit derived from the methacrylic acid ester is within the range described below.
　メタクリル系重合体（ｂ）を構成するメタクリル酸エステルは、メタクリル酸メチルなどのアルキル基の炭素数１～１２のメタクリル酸アルキルエステルであることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 The methacrylic acid ester constituting the methacrylic polymer (b) is preferably a methacrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms, such as methyl methacrylate.
These may be used alone or in combination of two or more.
　メタクリル酸エステルの含有量は、メタクリル系重合体（ｂ）を構成する全構造単位に対して、５０質量％以上であることが好ましい。メタクリル酸エステルの含有量が５０質量％以上であることにより、メタクリル酸メチルに由来する構造単位を主成分として有するメタクリル系樹脂との相溶性が得られやすい。メタクリル酸エステルの含有量は、上記観点から、メタクリル系重合体（ｂ）を構成する全構造単位に対して、７０質量％以上であることがより好ましい。 The content of the methacrylic acid ester is preferably 50% by mass or more relative to all structural units constituting the methacrylic polymer (b). By having a content of the methacrylic acid ester of 50% by mass or more, compatibility with a methacrylic resin having a structural unit derived from methyl methacrylate as a main component is easily obtained. From the above viewpoint, the content of the methacrylic acid ester is more preferably 70% by mass or more relative to all structural units constituting the methacrylic polymer (b).
　メタクリル系重合体（ｂ）は、メタクリル酸エステルと共重合可能な他の単量体に由来する構造単位を更に有してもよい。共重合可能な他の単量体としては、例えば、アクリル酸メチル（メチルアクリレート）、アクリル酸エチル（エチルアクリレート）、アクリル酸ｎ－ブチル（ｎ－ブチルアクリレート）等のアクリル酸エステル；（メタ）アクリル酸ベンジル（ベンジル（メタ）アクリレート）、（メタ）アクリル酸ジシクロペンタニル（ジシクロペンタニル（メタ）アクリレート）、（メタ）アクリル酸フェノキシエチル（フェノキシエチル（メタ）アクリレート）等の脂環、複素環又は芳香環を有する（メタ）アクリル系単量体（環含有（メタ）アクリル系単量体）が挙げられる。 The methacrylic polymer (b) may further have a structural unit derived from another monomer copolymerizable with the methacrylic acid ester. Examples of the other copolymerizable monomer include acrylic acid esters such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), and n-butyl acrylate (n-butyl acrylate); and (meth)acrylic monomers having an alicyclic, heterocyclic or aromatic ring (ring-containing (meth)acrylic monomers) such as benzyl (meth)acrylate (benzyl (meth)acrylate), dicyclopentanyl (meth)acrylate (dicyclopentanyl (meth)acrylate), and phenoxyethyl (meth)acrylate (phenoxyethyl (meth)acrylate).
　共重合可能な他の単量体に由来する構造単位の含有量は、メタクリル系重合体（ｂ）を構成する全構造単位に対して、５０質量％以下であることが好ましく、３０質量％以下であることがより好ましい。 The content of structural units derived from other copolymerizable monomers is preferably 50% by mass or less, and more preferably 30% by mass or less, based on the total structural units constituting the methacrylic polymer (b).
　ゴム粒子におけるグラフト成分の比率（グラフト率）は、１０～２５０質量％の範囲内であることが好ましく、１５～１５０質量％の範囲内であることがより好ましい。グラフト率が、１０質量％以上であるとは、グラフト成分、すなわち、メタクリル酸エステルに由来する構造単位を主成分とするメタクリル系重合体（ｂ）の割合が適度に多いことを意味する。これにより、ゴム粒子とメタクリル系樹脂との相溶性を高めやすく、ゴム粒子を一層凝集させにくくする。また、光学フィルムの剛性などが損なわれにくい。一方、グラフト率が、２５０質量％以下であることにより、アクリル系ゴム状重合体（ａ）の割合が適度に少なくなりすぎないため、光学フィルムの靱性が損なわれにくい。また、光学フィルムの脆性を十分に改良できる。 The ratio of the graft component in the rubber particles (graft ratio) is preferably in the range of 10 to 250% by mass, and more preferably in the range of 15 to 150% by mass. A graft ratio of 10% by mass or more means that the ratio of the graft component, i.e., the methacrylic polymer (b) whose main component is a structural unit derived from a methacrylic acid ester, is appropriately high. This makes it easier to increase the compatibility between the rubber particles and the methacrylic resin, making the rubber particles even less likely to aggregate. In addition, the rigidity of the optical film is less likely to be impaired. On the other hand, by having a graft ratio of 250% by mass or less, the ratio of the acrylic rubber-like polymer (a) is not too low, so that the toughness of the optical film is less likely to be impaired. In addition, the brittleness of the optical film can be sufficiently improved.
　グラフト率は、下記の方法で測定できる。 The graft rate can be measured using the following method.
　１）コアシェル型の粒子２ｇを、メチルエチルケトン５０ｍｌに溶解させ、遠心分離機「ＣＰ６０Ｅ」（工機ホールディングス株式会社製）を用い、回転数３００００ｒｐｍ、温度１２℃にて１時間遠心し、不溶分と可溶分とに分離する（遠心分離作業を合計３回セット）。
　２）得られた不溶分の質量を下記式に当てはめて、グラフト率を算出する。
　式：　グラフト率（質量％）＝［｛（メチルエチルケトン不溶分の質量）－（アクリル系ゴム状重合体（ａ）の質量）｝／（アクリル系ゴム状重合体（ａ）の質量）］×１００ 1) 2 g of core-shell type particles are dissolved in 50 ml of methyl ethyl ketone, and centrifuged at 30,000 rpm and 12°C for 1 hour using a centrifuge "CP60E" (manufactured by Koki Holdings Co., Ltd.) to separate the insoluble and soluble fractions (the centrifugation process is repeated a total of three times).
2) The mass of the insoluble matter thus obtained is applied to the following formula to calculate the graft ratio.
Formula: Graft ratio (mass %)=[{(mass of methyl ethyl ketone insoluble matter)−(mass of acrylic rubber-like polymer (a))}/(mass of acrylic rubber-like polymer (a)]×100
　（１．１．２．２）ゴム粒子の物性
　ゴム粒子の形状は、特に制限されないが、真球状に近い形状であることが好ましい。
　「真球状に近い形状」とは、光学フィルムの断面又は表面を観察したときの、ゴム粒子のアスペクト比が、１～２の範囲内となるような形状のことをいう。 (1.1.2.2) Physical Properties of Rubber Particles The shape of the rubber particles is not particularly limited, but it is preferable that the rubber particles have a shape close to a perfect sphere.
The term "nearly spherical" refers to a shape in which the aspect ratio of the rubber particles is within the range of 1 to 2 when the cross section or surface of the optical film is observed.
　このように、ゴム粒子が真球状に近い形状であることにより、搬送時におけるロールとの接触による積層体の変形や、巻き取り時の内部応力による変形に対して、十分な耐性が得られる。 In this way, because the rubber particles are nearly spherical, the laminate is sufficiently resistant to deformation caused by contact with the rolls during transportation and deformation caused by internal stress during winding.
　ゴム粒子の平均粒子径は、１００～４００ｎｍの範囲内であることが好ましい。１００ｎｍ以上であることにより、光学フィルムに十分な靱性や応力緩和性を付与できる。また、４００ｎｍ以下であることにより、光学フィルムの透明性が損なわれにくい。ゴム粒子の平均粒子径は、上記観点から、１５０～３００ｎｍの範囲内であることがより好ましい。 The average particle size of the rubber particles is preferably within the range of 100 to 400 nm. Having a particle size of 100 nm or more provides the optical film with sufficient toughness and stress relaxation properties. Furthermore, having a particle size of 400 nm or less ensures that the transparency of the optical film is not easily impaired. From the above viewpoints, it is more preferable that the average particle size of the rubber particles is within the range of 150 to 300 nm.
　ゴム粒子の平均粒子径は、以下の方法で算出できる。 The average particle size of rubber particles can be calculated using the following method.
　ゴム粒子の平均粒子径は、積層体の表面又は切片の、走査型電子顕微鏡（ＳＥＭ）撮影又は透過型電子顕微鏡（ＴＥＭ）撮影によって得た粒子１００個の円相当径の平均値として測定できる。円相当径は、撮影によって得られた粒子の投影面積を、同じ面積を持つ円の直径に換算することによって求めることができる。この際、倍率５０００倍でＳＥＭ観察又はＴＥＭ観察によって観察されるゴム粒子を、平均粒子径の算出に使用する。 The average particle size of rubber particles can be measured as the average of the circle-equivalent diameters of 100 particles obtained by photographing the surface or slices of the laminate with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The circle-equivalent diameter can be calculated by converting the projected area of the particle obtained by photographing into the diameter of a circle with the same area. In this case, rubber particles observed by SEM or TEM observation at a magnification of 5000 times are used to calculate the average particle size.
　（１．１．３）着色剤
　本発明に係る光学フィルムは、着色剤を含有することにより、光透過率を調整できる。着色剤は、一種単独で用いても、二種以上を併用してもよい。
　着色剤の含有量は、輝度と色域のバランスの観点から、上記光学フィルム用樹脂の全質量に対して、０．０５～１．０２質量％の範囲内であることが好ましい。 (1.1.3) Colorant The optical film according to the present invention can adjust the light transmittance by containing a colorant. The colorant may be used alone or in combination of two or more kinds.
From the viewpoint of the balance between brightness and color gamut, the content of the colorant is preferably within the range of 0.05 to 1.02% by mass based on the total mass of the resin for optical films.
　着色剤を二種以上併用する場合、少なくとも一種が、５７０～６１０ｎｍの波長領域に吸収極大波長を有する着色剤であることが好ましい。これにより、光学フィルムの、５７０～６１０ｎｍの波長領域の平均光透過率を下げることができ、表示装置の色域が狭くなることを抑制できる。 When two or more colorants are used in combination, it is preferable that at least one of them has a maximum absorption wavelength in the wavelength region of 570 to 610 nm. This makes it possible to reduce the average light transmittance of the optical film in the wavelength region of 570 to 610 nm, and to prevent the color gamut of the display device from narrowing.
　そして、５７０～６１０ｎｍの波長領域に存在する吸収極大波長が、当該着色剤における最大の吸収極大波長であることがより好ましい。なお、「最大の吸収極大波長」とは、吸収極大波長が１つのみの場合はその吸収極大波長を、吸収極大波長が複数ある場合はその中で最大の吸光度を示す吸収極大波長のことをいう。 It is more preferable that the absorption maximum wavelength in the wavelength region of 570 to 610 nm is the maximum absorption maximum wavelength of the colorant. Note that "maximum absorption maximum wavelength" refers to the absorption maximum wavelength when there is only one absorption maximum wavelength, and to the absorption maximum wavelength that shows the maximum absorbance when there are multiple absorption maximum wavelengths.
　輝度と色域のバランスの観点から、５７０～６１０ｎｍの波長領域に吸収極大波長を有する着色剤の含有量は、上記光学フィルム用樹脂の全質量に対して、０．０２～０．６質量％の範囲内であることが好ましく、０．０５～０．３質量％の範囲内であることがより好ましい。 From the viewpoint of the balance between brightness and color gamut, the content of the colorant having a maximum absorption wavelength in the wavelength region of 570 to 610 nm is preferably within the range of 0.02 to 0.6 mass %, and more preferably within the range of 0.05 to 0.3 mass %, relative to the total mass of the resin for optical films.
　さらに、着色剤を二種以上併用する場合、少なくとも一種が、４２０～４６０ｎｍの波長領域に吸収極大波長を有する着色剤であることが好ましい。これにより、光学フィルムの可視光領域における平均光透過率を、効率的に下げることができる。
　そして、４２０～４６０ｎｍの波長領域に存在する吸収極大波長が当該着色剤における最大の吸収極大波長であることがより好ましい。 Furthermore, when two or more kinds of colorants are used in combination, at least one of them is preferably a colorant having a maximum absorption wavelength in the wavelength region of 420 to 460 nm, which can efficiently reduce the average light transmittance of the optical film in the visible light region.
It is more preferable that the absorption maximum wavelength in the wavelength region of 420 to 460 nm is the longest absorption maximum wavelength of the colorant.
　輝度と色域のバランスの観点から、４２０～４６０ｎｍの波長領域に吸収極大波長を有する着色剤の含有量は、上記光学フィルム用樹脂の全質量に対して、０．００５～０．３質量％の範囲内であることが好ましく、０．０１～０．３質量％の範囲内であることがより好ましい。 From the viewpoint of the balance between brightness and color gamut, the content of the colorant having a maximum absorption wavelength in the wavelength region of 420 to 460 nm is preferably within the range of 0.005 to 0.3 mass %, and more preferably within the range of 0.01 to 0.3 mass %, relative to the total mass of the resin for optical films.
　上記吸収極大波長は、着色剤をジクロロメタンに分散させ、紫外可視分光光度計（例えば「ＵＶ－２４５０」（株式会社島津製作所製））を用いて、吸収スペクトルを測定することによって求めることができる。 The above absorption maximum wavelength can be determined by dispersing the colorant in dichloromethane and measuring the absorption spectrum using an ultraviolet-visible spectrophotometer (e.g., "UV-2450" (manufactured by Shimadzu Corporation)).
　着色剤は、市販品を用いても合成品を用いてもよい。
　市販品としては、特に制限されないが、例えば、「＃９５０」（三菱ケミカル株式会社製）、「ＦＤＲシリーズ」、「ＦＤＧシリーズ」、「ＦＤＢシリーズ」（以上、山田化学工業株式会社製）、「Ｋａｙａｓｅｔ　Ｂｌａｃｋ　Ａ－Ｎ」（日本化薬株式会社製）、「ＮＵＢＩＡＮ（登録商標）ＢＬＡＣＫ　ＰＣ－５８５７」（オリエント化学工業株式会社製）、「Ｐｌａｓｔ　Ｂｌａｃｋ　８９５０－Ｎ」（有本化学工業株式会社製）等が挙げられる。 The coloring agent may be a commercially available product or a synthetic product.
Examples of commercially available products include, but are not limited to, "#950" (manufactured by Mitsubishi Chemical Corporation), "FDR series", "FDG series", and "FDB series" (all manufactured by Yamada Chemical Industry Co., Ltd.), "Kayaset Black A-N" (manufactured by Nippon Kayaku Co., Ltd.), "NUBIAN (registered trademark) BLACK PC-5857" (manufactured by Orient Chemical Industry Co., Ltd.), and "Plast Black 8950-N" (manufactured by Arimoto Chemical Industry Co., Ltd.).
　着色剤としては、特に制限されず、染料、顔料等が挙げられる。 The coloring agent is not particularly limited, but examples include dyes and pigments.
　（１．１．３．１）染料
　染料としては、特に制限されず、例えば下記のものが挙げられる。
　ただし、幅広い波長の光を吸収できる観点から、下記の染料を少なくとも二種以上併用することが好ましい。また、染料を二種以上併用し混合させた市販品を使用してもよい。 (1.1.3.1) Dyes The dyes are not particularly limited, and examples thereof include the following.
However, from the viewpoint of absorbing light of a wide wavelength range, it is preferable to use at least two or more of the following dyes in combination. Also, a commercially available product in which two or more dyes are mixed in combination may be used.
　マゼンタ染料としては、「ＭＳ　Ｍａｇｅｎｔａ　ＶＰ」、「ＭＳ　Ｍａｇｅｎｔａ　ＨＭ－１４５０」、「ＭＳ　Ｍａｇｅｎｔａ　ＨＳｏ－１４７」（以上、三井東圧社製）、「ＡＩＺＥＮＳＯＴ　Ｒｅｄ－１」、「ＡＩＺＥＮＳＯＴ　Ｒｅｄ－２」、「ＡＩＺＥＮＳＯＴ　Ｒｅｄ－３」、「ＡＩＺＥＮＳＯＴ　Ｐｉｎｋ－１」、「ＳＰＩＲＯＮ　Ｒｅｄ　ＧＥＨ　ＳＰＥＣＩＡＬ」（以上、保土谷化学社製）、「ＲＥＳＯＬＩＮ　Ｒｅｄ　ＦＢ　２００％」、「ＭＡＣＲＯＬＥＸ（登録商標）Ｒｅｄ　Ｖｉｏｌｅｔ　Ｒ」、「ＭＡＣＲＯＬＥＸ（登録商標）ＲＯＴ５Ｂ」（以上、バイエルジャパン社製）、「ＫＡＹＡＳＥＴ　Ｒｅｄ　Ｂ」、「ＫＡＹＡＳＥＴ　Ｒｅｄ　１３０」、「ＫＡＹＡＳＥＴ　Ｒｅｄ　８０２」（以上、日本化薬社製）、「ＰＨＬＯＸＩＮ、ＲＯＳＥ　ＢＥＮＧＡＬ」、「ＡＣＩＤ　Ｒｅｄ」（以上、ダイワ化成社製）、「ＨＳＲ－３１」、「ＤＩＡＲＥＳＩＮ（登録商標）Ｒｅｄ　Ｋ」（以上、三菱化成社製）、「ＯｉｌＲｅｄ」（ＢＡＳＦジャパン社製）等が挙げられる。 Magenta dyes include "MS Magenta VP", "MS Magenta HM-1450", "MS Magenta HSo-147" (all manufactured by Mitsui Toatsu Co., Ltd.), "AIZENSOT Red-1", "AIZENSOT Red-2", "AIZENSOT Red-3", "AIZENSOT Pink-1", "SPIRON Red GEH SPECIAL" (all manufactured by Hodogaya Chemical Co., Ltd.), "RESOLIN Red FB 200%", "MACROLEX (registered trademark) Re d Violet R, MACROLEX (registered trademark) ROT5B (all manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red 802 (all manufactured by Nippon Kayaku), PHLOXIN, ROSE BENGAL, ACID Red (all manufactured by Daiwa Kasei), HSR-31, DIARESIN (registered trademark) Red K (all manufactured by Mitsubishi Kasei), and Oil Red (manufactured by BASF Japan).
　シアン染料としては、「ＭＳ　Ｃｙａｎ　ＨＭ－１２３８」、「ＭＳ　Ｃｙａｎ　ＨＳｏ－１６」、「Ｃｙａｎ　ＨＳｏ－１４４」、「ＭＳ　Ｃｙａｎ　ＶＰＧ」（以上、三井東圧社製）、「ＡＩＺＥＮＳＯＴ　Ｂｌｕｅ－４」（保土谷化学社製）、「ＲＥＳＯＬＩＮ　ＢＲ．Ｂｌｕｅ　ＢＧＬＮ　２００％」、「ＭＡＣＲＯＬＥＸ（登録商標）Ｂｌｕｅ　ＲＲ」、「ＣＥＲＥＳ（登録商標）Ｂｌｕｅ　ＧＮ」、「ＳＩＲＩＵＳ（登録商標）ＳＵＰＲＡＴＵＲＱ．Ｂｌｕｅ　Ｚ－ＢＧＬ」、「ＳＩＲＩＵＳ（登録商標）ＳＵＰＲＡＴＵＲＱ．Ｂｌｕｅ　ＦＢ－ＬＬ３３０％」（以上、バイエルジャパン社製）、「ＫＡＹＡＳＥＴ　Ｂｌｕｅ　ＦＲ」、「ＫＡＹＡＳＥＴ　Ｂｌｕｅ　Ｎ」、「ＫＡＹＡＳＥＴ　Ｂｌｕｅ　８１４」、「Ｔｕｒｑ．Ｂｌｕｅ　ＧＬ－５２００」、「Ｌｉｇｈｔ　Ｂｌｕｅ　ＢＧＬ－５２００」（以上、日本化薬社製）、「ＤＡＩＷＡ　Ｂｌｕｅ　７０００」、「Ｏｌｅｏｓｏｌ（登録商標）Ｆａｓｔ　Ｂｌｕｅ　ＧＬ」（以上、ダイワ化成社製）、「ＤＩＡＲＥＳＩＮ（登録商標）Ｂｌｕｅ　Ｐ」（三菱化成社製）、「ＳＵＤＡＮ　Ｂｌｕｅ　６７０」、「ＮＥＯＰＥＮ　Ｂｌｕｅ　８０８」、「ＺＡＰＯＮ　Ｂｌｕｅ　８０６」（以上、ＢＡＳＦジャパン社製）等が挙げられる。 Cyan dyes include "MS Cyan HM-1238", "MS Cyan HSo-16", "Cyan HSo-144", and "MS Cyan VPG" (all manufactured by Mitsui Toatsu Co., Ltd.), "AIZENSOT Blue-4" (manufactured by Hodogaya Chemical Co., Ltd.), "RESOLIN BR.Blue BGLN 200%, "MACROLEX (registered trademark) Blue RR", "CERES (registered trademark) Blue GN", "SIRIUS (registered trademark) SUPRATURQ.Blue Z-BGL", and "SIRIUS (registered trademark) SUPRATURQ.Blue FB-LL 330%" (all manufactured by Bayer Japan Ltd.). Examples include "KAYASET Blue FR", "KAYASET Blue N", "KAYASET Blue 814", "Turq. Blue GL-5200", "Light Blue BGL-5200" (all manufactured by Nippon Kayaku Co., Ltd.), "DAIWA Blue 7000", "Oleosol (registered trademark) Fast Blue GL" (all manufactured by Daiwa Kasei Co., Ltd.), "DIARESIN (registered trademark) Blue P" (manufactured by Mitsubishi Kasei Corporation), "SUDAN Blue 670", "NEOPEN Blue 808", and "ZAPON Blue 806" (all manufactured by BASF Japan Ltd.).
　イエロー染料としては、「ＭＳ　Ｙｅｌｌｏｗ　ＨＳｍ－４１」、「Ｙｅｌｌｏｗ　ＫＸ－７」、「Ｙｅｌｌｏｗ　ＥＸ－２７」（以上、三井東圧社製）、「ＡＩＺＥＮＳＯＴ　Ｙｅｌｌｏｗ－１」、「ＡＩＺＥＮＳＯＴ　ＹｅｌｌｏＷ－３」、「ＡＩＺＥＮＳＯＴ　Ｙｅｌｌｏｗ－６」（以上、保土谷化学社製）、「ＭＡＣＲＯＬＥＸ（登録商標）Ｙｅｌｌｏｗ　６Ｇ」、「ＭＡＣＲＯＬＥＸ（登録商標）ＦＬＵＯＲ．Ｙｅｌｌｏｗ　１０ＧＮ」（以上、バイエルジャパン社製）、「ＫＡＹＡＳＥＴ　Ｙｅｌｌｏｗ　ＳＦ－Ｇ」、「ＫＡＹＡＳＥＴ　Ｙｅｌｌｏｗ　２Ｇ」、「ＫＡＹＡＳＥＴ　Ｙｅｌｌｏｗ　Ａ－Ｇ」、「ＫＡＹＡＳＥＴ　Ｙｅｌｌｏｗ　Ｅ－Ｇ」（以上、日本化薬社製）、「ＤＡＩＷＡ　Ｙｅｌｌｏｗ　３３０ＨＢ」（ダイワ化成社製）、「ＨＳＹ－６８」（三菱化成社製）、「ＳＵＤＡＮ　Ｙｅｌｌｏｗ　１４６」、「ＮＥＯＰＥＮ　Ｙｅｌｌｏｗ　０７５」（以上、ＢＡＳＦジャパン社製）等が挙げられる。 Yellow dyes include "MS Yellow HSm-41", "Yellow KX-7", and "Yellow EX-27" (all manufactured by Mitsui Toatsu Co., Ltd.), "AIZENSOT Yellow-1", "AIZENSOT Yellow W-3", and "AIZENSOT Yellow-6" (all manufactured by Hodogaya Chemical Co., Ltd.), "MACROLEX (registered trademark) Yellow 6G", and "MACROLEX (registered trademark) FLUOR.Yellow 10GN" (all manufactured by Bayer). Japan), "KAYASET Yellow SF-G", "KAYASET Yellow 2G", "KAYASET Yellow A-G", "KAYASET Yellow E-G" (all manufactured by Nippon Kayaku Co., Ltd.), "DAIWA Yellow 330HB" (manufactured by Daiwa Kasei Co., Ltd.), "HSY-68" (manufactured by Mitsubishi Kasei Co., Ltd.), "SUDAN Yellow 146", "NEOPEN Yellow 075" (all manufactured by BASF Japan Ltd.), etc.
　（１．１．３．２）顔料
　顔料としては、特に制限されず、例えば、カラーインデックスに記載される下記の番号の有機顔料、無機顔料、鉱物等が挙げられる。
　ただし、幅広い波長の光を吸収できる観点から、下記の顔料等を少なくとも二種以上併用することが好ましい。また、下記の顔料等を二種以上併用し混合させた市販品を使用してもよい。 (1.1.3.2) Pigments The pigments are not particularly limited, and examples thereof include organic pigments, inorganic pigments, minerals, etc., having the following numbers as described in the Color Index.
However, from the viewpoint of absorbing light of a wide wavelength range, it is preferable to use at least two or more of the following pigments in combination. Also, a commercially available product in which two or more of the following pigments are mixed in combination may be used.
　黒顔料としては、特に制限されず、例えば、カーボンブラック、磁性体、鉄・チタン複合酸化物ブラック等が挙げられる。カーボンブラックとしては、特に制限されず、例えば、チャンネルブラック、ファーネスブラック、アセチレンブラック、サーマルブラック、ランプブラック等が挙げられる。また、磁性体としては、特に制限されず、例えば、フェライト、マグネタイト等が挙げられる。 Black pigments are not particularly limited, and examples thereof include carbon black, magnetic materials, iron-titanium composite oxide black, etc. Carbon black is not particularly limited, and examples thereof include channel black, furnace black, acetylene black, thermal black, lamp black, etc. Magnetic materials are not particularly limited, and examples thereof include ferrite, magnetite, etc.
　赤又はマゼンタ顔料としては、特に制限されず、例えば、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ　Ｒｅｄ　３、５、１９、２２、３１、３８、４３、４８：１、４８：２、４８：３、４８：４、４８：５、４９：１、５３：１、５７：１、５７：２、５８：４、６３：１、８１、８１：１、８１：２、８１：３、８１：４、８８、１０４、１０８、１１２、１２２、１２３、１４４、１４６、１４９、１６６、１６８、１６９、１７０、１７７、１７８、１７９、１８４、１８５、２０８、２１６、２２６、２５７、Ｐｉｇｍｅｎｔ　Ｖｉｏｌｅｔ　３、１９、２３、２９、３０、３７、５０、８８、Ｐｉｇｍｅｎｔ　Ｏｒａｎｇｅ　１３、１６、２０、３６、ルビー（クロム含有コランダム）、ガーネット（柘榴石）、スピネル（尖晶石）等が挙げられる。 The red or magenta pigment is not particularly limited, and examples thereof include C.I. Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 1 69, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, Ruby (chromium-containing corundum), Garnet, Spinel, etc.
　青又はシアン顔料としては、特に制限されず、例えば、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ　Ｂｌｕｅ　１、１５、１５：１、１５：２、１５：３、１５：４、１５：６、１６、１７－１、２２、２７、２８、２９、３６、６０、ブルーサファイア（鉄、チタン含有コランダム）等が挙げられる。 The blue or cyan pigment is not particularly limited, and examples thereof include C.I. Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, 60, and Blue Sapphire (iron- and titanium-containing corundum).
　緑顔料としては、特に制限されず、例えば、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ　Ｇｒｅｅｎ　７、２６、３６、５０等が挙げられる。
　黄顔料としては、特に制限されず、例えば、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ　Ｙｅｌｌｏｗ　１、３、１２、１３、１４、１７、３４、３５、３７、５５、７４、８１、８３、９３、９４、９５、９７、１０８、１０９、１１０、１３７、１３８、１３９、１５３、１５４、１５５、１５７、１６６、１６７、１６８、１８０、１８５、１９３、イエローサファイア（ニッケル含有コランダム）等が挙げられる。 The green pigment is not particularly limited, and examples thereof include C.I. Pigment Green 7, 26, 36, 50, and the like.
The yellow pigment is not particularly limited, and examples thereof include C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and yellow sapphire (nickel-containing corundum).
　着色剤が顔料である場合、顔料の平均二次粒子径は、特に制限されないが、０．１μｍ以上であることが好ましく、０．２μｍ以上であることがより好ましい。上記範囲内であることにより、顔料粒子の摺動性が向上し、凝集し難くなるため、光学フィルム内の光透過率のムラがより減少する。 When the colorant is a pigment, the average secondary particle diameter of the pigment is not particularly limited, but is preferably 0.1 μm or more, and more preferably 0.2 μm or more. By keeping it within the above range, the sliding properties of the pigment particles are improved and they are less likely to aggregate, which further reduces unevenness in the light transmittance within the optical film.
　また、顔料の平均二次粒子径は、特に制限されないが、３μｍ以下であることが好ましく、２．６μｍ以下であることがより好ましい。上記範囲内であることにより、光学フィルム中の分散斑がより発生し難くなり、光学フィルム内の光透過率のムラがより減少し、ヘイズ値も低下する。 The average secondary particle diameter of the pigment is not particularly limited, but is preferably 3 μm or less, and more preferably 2.6 μm or less. By keeping it within the above range, dispersion spots in the optical film are less likely to occur, unevenness in the light transmittance in the optical film is further reduced, and the haze value is also reduced.
　顔料の平均二次粒子径は、光学フィルムの電子顕微鏡写真から二次粒子の大きさを直接計測する方法で求めることができる。具体的には、透過型電子顕微鏡写真（ＴＥＭ）「Ｈ－７６５０」（株式会社日立ハイテク製）を用いて粒子像を測定し、ランダムに選択した１００個の二次粒子の等面積円相当直径の平均値を求め、この値を平均二次粒子径とする。 The average secondary particle diameter of a pigment can be determined by directly measuring the size of the secondary particles from an electron microscope photograph of an optical film. Specifically, a transmission electron microscope (TEM) "H-7650" (Hitachi High-Tech Corporation) is used to measure particle images, and the average equivalent diameter of a circle with an equal area of 100 randomly selected secondary particles is calculated, and this value is taken as the average secondary particle diameter.
　（１．１．４）微粒子
　フィルムの滑り性付与の観点から、光学フィルムは、微粒子を更に含有することが好ましい。 (1.1.4) Fine Particles From the viewpoint of imparting slip properties to the film, it is preferable that the optical film further contains fine particles.
　無機化合物の微粒子としては、例えば、二酸化ケイ素、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、炭酸カルシウム、タルク、クレイ、焼成カオリン、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウム、及びリン酸カルシウムが挙げられる。 Examples of inorganic compound particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate.
　有機化合物の微粒子としては、例えば、ポリテトラフルオロエチレン、セルロースアセテート、ポリスチレン、ポリメチルメタクリレート、ポリプロピルメタクリレート、ポリメチルアクリレート、ポリエチレンカーボネート、アクリルスチレン系樹脂、シリコーン系樹脂、ポリカーボネート、ベンゾグアナミン系樹脂、メラミン系樹脂、ポリオレフィン系粉末、ポリエステル、ポリアミド、ポリイミド、ポリフッ化エチレン系樹脂等が挙げられる。その他、澱粉等の有機高分子化合物の粉砕分級物や、懸濁重合法で合成した高分子化合物等も挙げられる。 Examples of fine particles of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resins, silicone resins, polycarbonate, benzoguanamine resins, melamine resins, polyolefin powders, polyester, polyamide, polyimide, polyethylene fluoride resins, etc. Other examples include crushed fractions of organic polymer compounds such as starch, and polymer compounds synthesized by suspension polymerization.
　微粒子は、濁度が低くなる観点から、ケイ素を含有することが好ましく、二酸化ケイ素を含有することがより好ましい。そのような微粒子の市販品としては、例えば、アエロジル（登録商標、以下同じ）Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ８１２、２００、２００Ｖ、３００、Ｒ２０２、ＯＸ５０、ＴＴ６００（以上、日本アエロジル株式会社製）等が挙げられる。 The fine particles preferably contain silicon, and more preferably silicon dioxide, from the viewpoint of reducing turbidity. Commercially available products of such fine particles include, for example, Aerosil (registered trademark, the same applies below) R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.).
　微粒子の含有量は、光学フィルムの全質量に対して、０．０５～１０質量％の範囲内であることが好ましい。 The content of the fine particles is preferably within the range of 0.05 to 10% by mass relative to the total mass of the optical film.
　（１．２）光学フィルムの作製方法
　光学フィルムの作製方法は、特に制限されないが、所望の光学フィルムが得られる観点から、溶液流延法により作製することが好ましい。
　なお、光学フィルムＡ及び光学フィルムＢの作製方法は、同一であっても、同一でなくてもよい。 (1.2) Method for Producing Optical Film The method for producing the optical film is not particularly limited, but from the viewpoint of obtaining a desired optical film, it is preferable to produce the optical film by a solution casting method.
The optical film A and the optical film B may or may not be produced by the same method.
　溶液流延法では、樹脂、溶剤、及び任意の他の成分を含有するドープを調製した後、当該ドープを基材に付与し、その後乾燥し、光学フィルムを得る。 In the solution casting method, a dope containing a resin, a solvent, and any other ingredients is prepared, and then the dope is applied to a substrate and then dried to obtain an optical film.
　以下、溶液流延法による光学フィルムの作製方法について説明する。 The following describes how to make an optical film using the solution casting method.
　（１．２．１）ドープの調製
　（１．２．１．１）溶剤
　ドープに用いられる溶剤は、樹脂や、必要に応じて、ゴム粒子、着色剤等を良好に分散できるものであれば、特に制限されない。溶剤としては、例えば、メタノール、エタノール、プロパノール、ｎ－ブタノール、２－ブタノール、ｔｅｒｔ－ブタノール、シクロヘキサノールなどのアルコール類；メチルエチルケトン（ＭＥＫ）、メチルイソブチルケトン、アセトンなどのケトン類；酢酸エチル、酢酸メチル、乳酸エチル、酢酸イソプロピル、酢酸アミル、酪酸エチルなどのエステル類；テトラヒドロフラン（ＴＨＦ）、１，４－ジオキサン等のエーテル類；グリコールエーテル類；トルエン、ベンゼン、シクロヘキサン、ｎ－ヘキサン等の炭化水素類等が挙げられる。 (1.2.1) Preparation of dope (1.2.1.1) Solvent The solvent used for the dope is not particularly limited as long as it can disperse the resin and, if necessary, rubber particles, colorant, etc. well. Examples of the solvent include alcohols such as methanol, ethanol, propanol, n-butanol, 2-butanol, tert-butanol, cyclohexanol, etc.; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone, acetone, etc.; esters such as ethyl acetate, methyl acetate, ethyl lactate, isopropyl acetate, amyl acetate, ethyl butyrate, etc.; ethers such as tetrahydrofuran (THF), 1,4-dioxane, etc.; glycol ethers; and hydrocarbons such as toluene, benzene, cyclohexane, n-hexane, etc.
　グリコールエーテル類としては、プロピレングリコールモノ（Ｃ１～Ｃ４）アルキルエーテル、又はプロピレングリコールモノ（Ｃ１～Ｃ４）アルキルエーテルエステルが挙げられる。
　プロピレングリコールモノ（Ｃ１～Ｃ４）アルキルエーテルとしては、例えば、プロピレングリコールモノメチルエーテル（ＰＧＭＥ）、プロピレングリコールモノエチルエーテル、プロピレングリコールモノ－ｎ－プロピルエーテル、プロピレングリコールモノイソプロピルエーテル、プロピレングリコールモノブチルエーテル等が挙げられる。
　プロピレングリコールモノ（Ｃ１～Ｃ４）アルキルエーテルエステルとしては、例えば、プロピレングリコールモノメチルエーテルアセテート、プロピレングリコールモノエチルエーテルアセテート等が挙げられる。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of glycol ethers include propylene glycol mono (C1-C4) alkyl ethers and propylene glycol mono (C1-C4) alkyl ether esters.
Examples of propylene glycol mono(C1-C4) alkyl ethers include propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, and propylene glycol monobutyl ether.
Examples of propylene glycol mono (C1-C4) alkyl ether esters include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and the like.
These may be used alone or in combination of two or more.
　中でも、樹脂材料を溶解しやすく、低沸点で、乾燥速度及び生産性を高めやすい観点から、メチルエチルケトン、酢酸エチル、アセトン又はテトラヒドロフランであることが好ましい。なお、上記で挙げた溶剤に対して、ジクロロメタン等の溶剤を更に混合して使用してもよい。 Among these, methyl ethyl ketone, ethyl acetate, acetone, or tetrahydrofuran is preferred from the viewpoints of ease of dissolving the resin material, low boiling point, and ease of increasing the drying speed and productivity. Note that the above-mentioned solvents may be further mixed with a solvent such as dichloromethane.
　ドープの固形分濃度は、粘度を調整しやすくする等の観点から、例えば５～２０質量％の範囲内であることが好ましい。 The solids concentration of the dope is preferably within the range of, for example, 5 to 20% by mass in order to make it easier to adjust the viscosity.
　（１．２．１．２）他の成分
　ドープは、必要に応じて上記以外の他の成分を更に含有してもよい。他の成分としては、例えば、マット剤（微粒子）、紫外線吸収剤、界面活性剤等が挙げられる。 (1.2.1.2) Other Components The dope may further contain other components in addition to those described above, if necessary. Examples of the other components include a matting agent (fine particles), an ultraviolet absorbing agent, a surfactant, and the like.
　マット剤を添加することにより、光学フィルムに滑り性を付与できる。マット剤としては、例えば、シリカ粒子などの無機微粒子、ガラス転移温度が８０℃以上の有機微粒子などが挙げられる。 The addition of a matting agent can impart slipperiness to the optical film. Examples of matting agents include inorganic fine particles such as silica particles, and organic fine particles with a glass transition temperature of 80°C or higher.
　紫外線吸収剤としては、例えば、ベンゾトリアゾール系紫外線吸収剤、ベンゾフェノン系紫外線吸収剤、トリアジン系紫外線吸収剤等が挙げられる。 Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.
　界面活性剤としては、例えば、カルボン酸型、スルホン酸型、硫酸エステル型、リン酸エステル型等のアニオン性界面活性剤；アルキルアミン塩型、第４級アンモニウム塩型等のカチオン性界面活性剤；カルボキシベタイン型、２－アルキルイミダゾリンの誘導体型、グリシン型、アミンオキシド型等の両性界面活性剤が挙げられ、いずれの種類も使用できる。 Surfactants include, for example, anionic surfactants such as carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type; cationic surfactants such as alkylamine salt type and quaternary ammonium salt type; and amphoteric surfactants such as carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type. Any type can be used.
　（１．２．１．３）ドープの調製
　上記の樹脂、溶剤、及び任意の他の成分を、必要に応じて、攪拌しながら窒素下で混合し、ドープを調製する。 (1.2.1.3) Preparation of Dope The above resin, solvent, and any other ingredients are mixed under nitrogen with stirring, if necessary, to prepare a dope.
　ドープに含有される各成分の混合順序は、特に制限されない。各成分の混合方法も特に制限されず、例えば攪拌機などを用いて攪拌してもよい。 The order in which the components contained in the dope are mixed is not particularly limited. The method for mixing the components is also not particularly limited, and they may be mixed using, for example, a stirrer.
　混合時間（攪拌時間）は特に制限されないが、１～１０時間の範囲内であることが好ましい。また、混合温度（攪拌温度）も特に制限されないが、２０～５０℃の範囲内であることが好ましい。 The mixing time (stirring time) is not particularly limited, but is preferably within the range of 1 to 10 hours. The mixing temperature (stirring temperature) is also not particularly limited, but is preferably within the range of 20 to 50°C.
　ドープの２５℃における粘度は、所望の厚さの光学フィルムを作製できる程度であればよく、特に制限されないが、５～５０００ｍＰａ・ｓの範囲内であることが好ましい。ドープの粘度が、５ｍＰａ・ｓ以上であることにより、所望の厚さの光学フィルムを作製しやすい。また、５０００ｍＰａ・ｓ以下であることにより、溶液の粘度上昇によって、厚さのムラが生じるのを抑制できる。ドープの粘度は、同様の観点から、１００～１０００ｍＰａ・ｓの範囲内であることがより好ましい。なお、ドープの２５℃における粘度は、Ｅ型粘度計で測定できる。 The viscosity of the dope at 25°C is not particularly limited as long as it is sufficient to produce an optical film of the desired thickness, but it is preferably within the range of 5 to 5000 mPa·s. When the viscosity of the dope is 5 mPa·s or more, it is easy to produce an optical film of the desired thickness. Furthermore, when the viscosity is 5000 mPa·s or less, it is possible to suppress unevenness in thickness caused by an increase in the viscosity of the solution. From the same viewpoint, it is more preferable that the viscosity of the dope is within the range of 100 to 1000 mPa·s. The viscosity of the dope at 25°C can be measured with an E-type viscometer.
　得られたドープは、必要に応じてろ過を行ってもよい。ろ過方法は特に制限されず、従来公知の方法を適宜用いることができる。 The obtained dope may be filtered if necessary. There are no particular limitations on the filtration method, and any conventionally known method may be used.
　（１．２．２）光学フィルムの形成
　本発明に係る光学フィルムは、得られたドープを基材の表面に付与し、その後、乾燥して、ドープから溶剤を除去することにより、作製できる。なお、このとき、基材と光学フィルムを含む積層フィルムが作製される。
　以下、基材にドープを付与する工程、及び光学フィルムを形成する工程（乾燥工程）について説明する。 (1.2.2) Formation of Optical Film The optical film according to the present invention can be produced by applying the obtained dope to the surface of a substrate, and then drying the dope to remove the solvent from the dope. At this time, a laminated film including the substrate and the optical film is produced.
The step of applying the dope to the substrate and the step of forming the optical film (drying step) will be described below.
　（１．２．２．１）ドープを付与する工程
　本工程では、上記で得られたドープを、基材の表面に付与する。具体的には、当該ドープを、基材の表面に塗布する。 (1.2.2.1) Step of applying dope In this step, the dope obtained above is applied to the surface of the substrate. Specifically, the dope is coated on the surface of the substrate.
　基材は、光学フィルムを支持できるものであればよく、特に制限されないが、通常、樹脂フィルムであることが好ましい。 The substrate is not particularly limited as long as it can support the optical film, but it is usually preferable for it to be a resin film.
　基材用樹脂フィルムとしては、例えば、ポリエステル樹脂フィルム（例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリトリメチレンテレフタレート（ＰＴＴ）、ポリブチレンテレフタレート（ＰＢＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリブチレンナフタレート（ＰＢＮ）など）、シクロオレフィン樹脂フィルム（ＣＯＰ）、アクリル系フィルム、セルロース系樹脂フィルム（例えば、セルローストリアセテートフィルム（ＴＡＣ）など）が挙げられる。
　中でも、汎用性があり、かつ引張弾性率が高い観点から、ＰＥＴフィルム、セルローストリアセテートフィルム（ＴＡＣ）又はシクロオレフィン樹脂フィルムであることが好ましい。 Examples of the resin film for the substrate include polyester resin films (e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.), cycloolefin resin films (COP), acrylic films, and cellulose resin films (e.g., cellulose triacetate film (TAC)).
Among these, from the viewpoints of versatility and high tensile modulus of elasticity, a PET film, a cellulose triacetate film (TAC) or a cycloolefin resin film is preferred.
　基材用樹脂フィルムは、熱緩和されたものであってもよいし、延伸処理されたものであってもよい。 The resin film for the substrate may be one that has been heat-relaxed or stretched.
　基材用樹脂フィルムを熱緩和処理することにより、結晶化度及び配向性をいずれも低下させることができ、基材用樹脂フィルムの引張弾性率を低下させることができる。熱緩和温度は、特に制限されないが、基材用樹脂フィルムを構成する樹脂のガラス転移温度をＴｇとしたとき、（Ｔｇ＋６０）～（Ｔｇ＋１８０）℃の範囲内で行うことが好ましい。熱緩和は、離型層を作製する前に行われてもよいし、離型層を作製した後に行われてもよい。 By subjecting the substrate resin film to a heat-relaxing treatment, both the crystallinity and orientation can be reduced, and the tensile modulus of the substrate resin film can be reduced. The heat-relaxing temperature is not particularly limited, but is preferably within the range of (Tg+60) to (Tg+180)°C, where Tg is the glass transition temperature of the resin that constitutes the substrate resin film. Heat-relaxing may be performed before or after the release layer is produced.
　延伸処理は、基材用樹脂フィルムを延伸することで、樹脂分子の配向性を高めることができ、基材用樹脂フィルムの引張弾性率を高めることができる。延伸処理は、例えば、基材用樹脂フィルムの一軸方向に行ってもよいし、二軸方向に行ってもよい。延伸処理は、任意の条件で行うことができ、例えば、延伸倍率１２０～９００％の範囲内で行うことが好ましい。ここでの延伸倍率は、各方向の延伸倍率を乗じた値である。
　基材用樹脂フィルムが延伸されているかどうか（延伸フィルムであるかどうか）は、例えば、面内遅層軸（屈折率が最大となる方向に延びた軸）があるかどうかによって確認することができる。 The stretching treatment can increase the orientation of the resin molecules by stretching the substrate resin film, and can increase the tensile modulus of the substrate resin film. The stretching treatment may be performed, for example, in the uniaxial direction of the substrate resin film or in the biaxial direction. The stretching treatment may be performed under any conditions, and is preferably performed, for example, in a range of a stretch ratio of 120 to 900%. The stretch ratio here is a value obtained by multiplying the stretch ratios in each direction.
Whether or not the substrate resin film is stretched (whether or not it is a stretched film) can be confirmed, for example, by whether or not it has an in-plane slow axis (an axis extending in the direction in which the refractive index is maximum).
　基材用樹脂フィルムは、表面に離型層を更に有することが好ましい。離型層を有することにより、光学フィルムを基材用樹脂フィルムから剥離しやすくする。 The substrate resin film preferably further has a release layer on its surface. The presence of the release layer makes it easier to peel the optical film from the substrate resin film.
　離型層は、公知の剥離剤又は離型剤を含有するものであればよく、特に制限されない。離型層に含有される剥離剤としては、シリコーン系剥離剤であっても、非シリコーン系剥離剤であってもよい。 The release layer is not particularly limited as long as it contains a known release agent or a release agent. The release agent contained in the release layer may be a silicone-based release agent or a non-silicone-based release agent.
　シリコーン系剥離剤としては、例えば、公知のシリコーン系樹脂が挙げられる。
　また、非シリコーン系剥離剤としては、例えば、ポリビニルアルコール又はエチレン－ビニルアルコール共重合体などに長鎖アルキルイソシアネートを反応させた長鎖アルキルペンダント型重合体、オレフィン系樹脂（例えば、共重合ポリエチレン、環状ポリオレフィン、ポリメチルペンテンなど）、ポリアリレート樹脂（例えば、芳香族ジカルボン酸成分と二価フェノール成分との重縮合物など）、フッ素樹脂（例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリフッ化ビニル（ＰＶＦ）、四フッ化エチレンとパーフルオロアルコキシエチレンとの共重合体（ＰＦＡ）、テトラフルオロエチレンとヘキサフルオロプロピレンの共重合体（ＦＥＰ）、テトラフルオロエチレンとエチレンの共重合体（ＥＴＦＥ）など）等が挙げられる。 Examples of the silicone-based release agent include known silicone-based resins.
Examples of non-silicone release agents include long-chain alkyl pendant polymers obtained by reacting polyvinyl alcohol or ethylene-vinyl alcohol copolymers with long-chain alkyl isocyanates, olefin resins (e.g., copolymerized polyethylene, cyclic polyolefins, polymethylpentene, etc.), polyarylate resins (e.g., polycondensates of aromatic dicarboxylic acid components and dihydric phenol components, etc.), and fluororesins (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), copolymers of tetrafluoroethylene and perfluoroalkoxyethylene (PFA), copolymers of tetrafluoroethylene and hexafluoropropylene (FEP), copolymers of tetrafluoroethylene and ethylene (ETFE), etc.).
　離型層は、必要に応じて添加剤を更に含有してもよい。添加剤としては、例えば、充填剤、滑剤（ワックス、脂肪酸エステル、脂肪酸アミドなど）、安定剤（酸化防止剤、熱安定剤、光安定剤など）、難燃剤、粘度調整剤、増粘剤、消泡剤、紫外線吸収剤等が挙げられる。 The release layer may further contain additives as necessary. Examples of additives include fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity adjusters, thickeners, defoamers, ultraviolet absorbers, etc.
　離型層の厚さは、所望の剥離性が得られる程度であればよく、特に制限されないが、０．１～１．０μｍの範囲内であることが好ましい。 The thickness of the release layer is not particularly limited as long as it provides the desired releasability, but it is preferably within the range of 0.1 to 1.0 μm.
　基材の厚さは、特に制限されないが、１０～１００μｍの範囲内であることが好ましく、２５～５０μｍの範囲内であることがより好ましい。 The thickness of the substrate is not particularly limited, but is preferably within the range of 10 to 100 μm, and more preferably within the range of 25 to 50 μm.
　ドープの塗布方法としては、特に制限されず、例えば、バックコート法、グラビアコート法、スピンコート法、ワイヤーバーコート法、ロールコート法等の公知の方法が挙げられる。
　中でも、薄くかつ均一な厚さの塗膜を形成できる観点から、バックコート法であることが好ましい。 The method for applying the dope is not particularly limited, and examples thereof include known methods such as back coating, gravure coating, spin coating, wire bar coating, and roll coating.
Among these, the back coating method is preferred from the viewpoint of forming a coating film that is thin and has a uniform thickness.
　（１．２．２．２）溶剤を除去する工程
　次いで、基材に付与されたドープから溶剤を除去して、光学フィルムを形成する。 (1.2.2.2) Step of Removing Solvent Next, the solvent is removed from the dope applied to the substrate to form an optical film.
　具体的には、基材に付与されたドープを乾燥させる。乾燥方法としては、例えば、送風又は加熱が挙げられる。中でも、積層フィルムのカールを抑制しやすい観点から、送風により乾燥させることが好ましい。 Specifically, the dope applied to the substrate is dried. Drying methods include, for example, blowing air or heating. Among these, drying by blowing air is preferred from the viewpoint of easily suppressing curling of the laminated film.
　乾燥条件（例えば、乾燥温度、雰囲気中の溶剤濃度、乾燥時間など）を調整することにより、乾燥後の塗膜、すなわち光学フィルムの残留溶剤量を一定以下にすることができる。また、乾燥条件によって、光学フィルムにおけるゴム粒子の分布状態を調整できる。具体的には、ゴム粒子を偏在させやすくする観点から、ゴム粒子との親和性が良好な溶剤を用い、かつ乾燥温度は高く、雰囲気中の溶剤濃度は低くすることが好ましい。 By adjusting the drying conditions (e.g., drying temperature, solvent concentration in the atmosphere, drying time, etc.), the amount of residual solvent in the coating film after drying, i.e., the optical film, can be kept below a certain level. In addition, the distribution state of the rubber particles in the optical film can be adjusted by adjusting the drying conditions. Specifically, from the viewpoint of making it easier to unevenly distribute the rubber particles, it is preferable to use a solvent that has good affinity with the rubber particles, to set the drying temperature high, and to set the solvent concentration in the atmosphere low.
　乾燥温度は、溶剤の沸点をＴｂ（℃）としたとき、（Ｔｂ－５０）～（Ｔｂ＋５０）℃の範囲内であることが好ましく、（Ｔｂ－４０）～（Ｔｂ＋４０）℃の範囲内であることがより好ましい。乾燥温度が下限値以上であることにより、溶剤の蒸発速度を高くすることでき、ゴム粒子を偏在させやすい。また、上限値以下であることにより、雰囲気中の溶剤濃度が高くなりすぎるのを抑制できる。例えば、アセトン及びメタノールの混合溶剤を用いる場合、乾燥温度は、４０℃以上であることが好ましい。 The drying temperature is preferably within the range of (Tb-50) to (Tb+50)°C, and more preferably within the range of (Tb-40) to (Tb+40)°C, where Tb is the boiling point of the solvent (°C). By having a drying temperature equal to or higher than the lower limit, the evaporation rate of the solvent can be increased, making it easier to unevenly distribute the rubber particles. Furthermore, by having a drying temperature equal to or lower than the upper limit, it is possible to prevent the solvent concentration in the atmosphere from becoming too high. For example, when using a mixed solvent of acetone and methanol, the drying temperature is preferably 40°C or higher.
　乾燥時の雰囲気中の溶剤濃度は、０．１０～０．３０質量％の範囲内であることが好ましく、０．１０～０．２０質量％であることがより好ましい。０．１０質量％以上であることにより、溶剤が蒸発しすぎるのを抑制でき、塗膜に割れなどを生じにくくすることができる。また、０．３０質量％以下であることにより、塗膜からの溶剤の蒸発速度を適度に高くでき、ゴム粒子を表面に偏在させやすい。雰囲気中の溶剤濃度は、乾燥温度と、乾燥炉内露点温度とによって調整できる。また、雰囲気中の溶剤濃度は、赤外線ガス濃度計により測定できる。 The solvent concentration in the atmosphere during drying is preferably in the range of 0.10 to 0.30 mass%, and more preferably 0.10 to 0.20 mass%. By making it 0.10 mass% or more, excessive evaporation of the solvent can be prevented, making it less likely for the coating film to crack. Furthermore, by making it 0.30 mass% or less, the evaporation rate of the solvent from the coating film can be increased appropriately, making it easier for the rubber particles to be unevenly distributed on the surface. The solvent concentration in the atmosphere can be adjusted by the drying temperature and the dew point temperature inside the drying oven. Furthermore, the solvent concentration in the atmosphere can be measured with an infrared gas concentration meter.
　このようにして得られた基材と光学フィルムとの積層フィルムから基材を剥離することにより、本発明に係る光学フィルムが得られる。 The optical film according to the present invention is obtained by peeling off the substrate from the laminate film of the substrate and optical film thus obtained.
　（１．３）光学フィルムの物性
　光学フィルムＡ及び光学フィルムＢは、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、ＴＡ及びＴＢが、下記式（１）を満たし、かつＴＡ及びＴＢが、共に３９～８９％の範囲内である。
　式（１）：　ＴＡ＞ＴＢ (1.3) Physical Properties of Optical Films When the average light transmittances of the optical films A and B in the wavelength region of 380 to 780 nm are T A and T B , respectively, T A and T B satisfy the following formula (1) and both T A and T B are within the range of 39 to 89%.
Formula (1): TA > TB
　３８０～７８０ｎｍの波長領域（可視光領域）における平均光透過率は、下記の方法で測定できる。
　各光学フィルムを、気温２３℃、相対湿度５５ＲＨの空調室で２４時間調湿する。そして、ＪＩＳ　Ｋ－７３７５：２００８に準拠して、紫外可視分光光度計（例えば、「ＵＶ－２４５０」（株式会社島津製作所製））を用いて、３８０～７８０ｎｍの波長領域における各波長の全光線透過率を測定し、その算術平均値を求める。 The average light transmittance in the wavelength region of 380 to 780 nm (visible light region) can be measured by the following method.
Each optical film is conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, a total light transmittance of each wavelength in the wavelength region of 380 to 780 nm is measured using a UV-visible spectrophotometer (for example, “UV-2450” (manufactured by Shimadzu Corporation)), and the arithmetic average value is calculated.
　光学フィルムＡが、光学フィルムＢよりも視認側に配置されるよう、本発明の積層体を表示装置に取り付けた場合、表示装置に対してペン入力を行うと、光学フィルムＡ側から、ペン入力を行うことになる。このとき、光学フィルムＢが、薄膜ガラスの裏面（視認側に近い方の面を表面としたときの裏面）に働く外側への引張応力を抑制することにより、薄膜ガラスがたわんで破損するのを防止（耐衝撃性）できる。 When the laminate of the present invention is attached to a display device so that optical film A is positioned closer to the viewing side than optical film B, pen input to the display device is performed from the optical film A side. At this time, optical film B suppresses the outward tensile stress acting on the back surface of the thin glass (the back surface when the surface closer to the viewing side is considered the front surface), thereby preventing the thin glass from bending and breaking (impact resistance).
　光学フィルムＡの２５℃における貯蔵弾性率は、耐衝撃性の観点から、２．０ＧＰａ以上であることが好ましい。
　光学フィルムＢの２５℃における貯蔵弾性率は、耐衝撃性及び屈曲後のコントラストの観点から、０．１～３．５ＧＰａの範囲内であることが好ましく、１．０～３．５ＧＰａの範囲内であることがより好ましい。 From the viewpoint of impact resistance, the storage modulus of the optical film A at 25° C. is preferably 2.0 GPa or more.
The storage modulus of the optical film B at 25° C. is preferably within a range of 0.1 to 3.5 GPa, and more preferably within a range of 1.0 to 3.5 GPa, from the viewpoints of impact resistance and contrast after bending.
　光学フィルムＢの２５℃における損失正接（ｔａｎδＢ）は、耐衝撃性の観点から、０．０１～０．３の範囲内であることが好ましく、０．０５～０．３の範囲内であることがより好ましい。 From the viewpoint of impact resistance, the loss tangent (tan δ B ) of the optical film B at 25° C. is preferably within a range of 0.01 to 0.3, and more preferably within a range of 0.05 to 0.3.
　光学フィルムの２５℃における貯蔵弾性率及び損失正接は、材料（樹脂、ゴム粒子等）の種類、含有量等を適宜選択することにより、調整できる。 The storage modulus and loss tangent of the optical film at 25°C can be adjusted by appropriately selecting the type and content of materials (resin, rubber particles, etc.).
　光学フィルムの２５℃における貯蔵弾性率及び損失正接は、レオメーター装置「ＲＳＡ－３」（ティー・エイ・インスツルメント・ジャパン株式会社製）を用い、下記の試験条件にて測定できる。
　試験条件（動的粘弾性試験）
　試験機：動的粘弾性測定装置「ＲＳＡ－３」（ティー・エイ・インスツルメント・ジャパン株式会社製）
　変形方法：引張
　プレロード荷重：５５ｇ
　温度範囲：－７０～２００℃
　周波数：１．０Ｈｚ
　変位：±０．１％
　サンプル：幅５ｍｍ
　チャック間距離：２０ｍｍ The storage modulus and loss tangent at 25° C. of the optical film can be measured using a rheometer device “RSA-3” (manufactured by TA Instruments Japan Co., Ltd.) under the following test conditions.
Test conditions (dynamic viscoelasticity test)
Testing machine: Dynamic viscoelasticity measuring device "RSA-3" (manufactured by TA Instruments Japan, Inc.)
Deformation method: tension Preload load: 55g
Temperature range: -70 to 200°C
Frequency: 1.0Hz
Displacement: ±0.1%
Sample: Width 5mm
Chuck distance: 20 mm
　光学フィルムは、下記式で表される面内位相差（Ｒ０）が、－１０～１０ｎｍの範囲内であることが好ましい。
　式：　Ｒ０＝（Ｎｘ－Ｎｙ）×ｄ The optical film preferably has an in-plane retardation (R 0 ) represented by the following formula in the range of −10 to 10 nm.
Formula: R 0 = (Nx - Ny) x d
　上記式において、Ｎｘは、光学フィルムの面内における最大方向の屈折率であり、Ｎｙは、光学フィルムの面内における最小の屈折率であり、ｄは光学フィルムの厚さである。 In the above formula, Nx is the maximum refractive index in the plane of the optical film, Ny is the minimum refractive index in the plane of the optical film, and d is the thickness of the optical film.
　面内位相差（Ｒ０）は、自動複屈折率計を用いて測定できる。例えば、自動複屈折率計「ＫＯＢＲＡ（登録商標）－２１ＡＤＨ」（王子計測機器株式会社製）を用いて、温度２３℃、湿度５５％ＲＨの環境下で、波長５９０ｎｍで測定できる。 The in-plane retardation (R 0 ) can be measured using an automatic birefringence meter, for example, an automatic birefringence meter "KOBRA (registered trademark)-21ADH" (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of a temperature of 23° C. and a humidity of 55% RH.
　光学フィルムの厚さは、本発明の積層体の薄膜化の観点から、１０～６０μｍの範囲内であることが好ましく、１５～５０μｍの範囲内であることがより好ましく、２０～４０μｍの範囲内であることが更に好ましい。 From the viewpoint of thinning the laminate of the present invention, the thickness of the optical film is preferably within the range of 10 to 60 μm, more preferably within the range of 15 to 50 μm, and even more preferably within the range of 20 to 40 μm.
　光学フィルムのガラス転移温度は、耐衝撃性の観点から、－３０～１８０℃の範囲内であることが好ましい。なお、光学フィルムのガラス転移温度を測定した際に複数のガラス転移温度が観測される場合には、観測される最も低いガラス転移温度を光学フィルムのガラス転移温度とする。 From the viewpoint of impact resistance, the glass transition temperature of the optical film is preferably within the range of -30 to 180°C. If multiple glass transition temperatures are observed when measuring the glass transition temperature of the optical film, the lowest glass transition temperature observed shall be regarded as the glass transition temperature of the optical film.
　ガラス転移温度（Ｔｇ）は、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｓｃａｎｎｉｎｇ　Ｃｏｌｏｒｉｍｅｔｒｙ：示差走査熱量装置）を用いて、ＪＩＳ　Ｋ　７１２１（２０１２）に準拠して測定できる。 The glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.
　（２）ガラス層
　（２．１）ガラス層（薄膜ガラス）の概要
　本発明に係るガラス層は、耐久性、平面性等に優れる観点から、薄膜ガラスであることが好ましい。薄膜ガラスの材料としては、例えば、アルミノケイ酸リチウムガラス、ソーダライムガラス、ホウケイ酸ガラス、シリカガラス、アルカリ金属アルミノケイ酸塩ガラス、低アルカリ含有量であるアルミノケイ酸塩ガラス等が挙げられる。 (2) Glass Layer (2.1) Overview of Glass Layer (Thin Film Glass) The glass layer according to the present invention is preferably a thin film glass from the viewpoint of excellent durability, flatness, etc. Examples of materials for thin film glass include lithium aluminosilicate glass, soda-lime glass, borosilicate glass, silica glass, alkali metal aluminosilicate glass, and aluminosilicate glass with a low alkali content.
　薄膜ガラスは、アルカリ成分を実質的に含有していない無アルカリガラスであることが好ましい。具体的には、アルカリ成分の含有量が、薄膜ガラスの全質量に対して、１０００質量ｐｐｍ以下であることが好ましく、５００質量ｐｐｍ以下であることがより好ましく、３００質量ｐｐｍ以下であることが更に好ましい。 The thin film glass is preferably an alkali-free glass that contains substantially no alkali components. Specifically, the content of alkali components is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less, relative to the total mass of the thin film glass.
　アルカリ成分を低減することにより、薄膜ガラス表面での陽イオンの置換を抑制し、ソーダ吹きと呼ばれる現象を抑制できる。これにより、薄膜ガラス表面の密度の低下を抑制でき、破損しづらくできる。 By reducing the alkaline content, it is possible to suppress the replacement of cations on the surface of the thin glass film, and to prevent a phenomenon known as soda blowing. This prevents the density of the thin glass surface from decreasing, making it less susceptible to breakage.
　薄膜ガラスの厚さは、１０～５０μｍの範囲内であることが好ましい。薄膜ガラスの厚さを１０μｍ以上とすることにより、積層体の十分な耐衝撃性が得られる。一方、薄膜ガラスの厚さを５０μｍ以下とすることにより、積層体の十分な屈曲性が得られる。また、薄膜ガラスの厚さを薄くするほど、積層体を薄型にでき、表示装置を薄型にできる。
　耐衝撃性及び屈曲後のコントラストを両立させる観点から、薄膜ガラスの厚さは、１０～４０μｍの範囲内であることがより好ましく、１０～３０μｍの範囲内であることが更
に好ましい。 The thickness of the thin film glass is preferably within a range of 10 to 50 μm. By making the thickness of the thin film glass 10 μm or more, sufficient impact resistance of the laminate can be obtained. On the other hand, by making the thickness of the thin film glass 50 μm or less, sufficient flexibility of the laminate can be obtained. Furthermore, the thinner the thin film glass is, the thinner the laminate can be, and the thinner the display device can be.
From the viewpoint of achieving both impact resistance and contrast after bending, the thickness of the thin glass is more preferably within the range of 10 to 40 μm, and further preferably within the range of 10 to 30 μm.
　（２．２）ガラス層（薄膜ガラス）の作製方法
　薄膜ガラス（ガラス層）は、一般的に知られた方法、例えばフロート法、ダウンドロー法、オーバーフローダウンドロー法等により作製できる。中でも、作製時に薄膜ガラスの表面が成形部材と接触せず、得られる薄膜ガラスの表面に傷がつきにくいことなどから、オーバーフローダウンドロー法又はフロート法であることが好ましい。中でも、厚さが１０～５０μｍの範囲内である薄膜ガラスを得られる観点から、フロート法であることが好ましい。 (2.2) Method for Producing Glass Layer (Thin Glass) Thin glass (glass layer) can be produced by a commonly known method, such as a float method, a down-draw method, an overflow down-draw method, etc. Among these, the overflow down-draw method or the float method is preferred because the surface of the thin glass does not come into contact with the forming member during production, and the surface of the obtained thin glass is less likely to be scratched. Among these, the float method is preferred from the viewpoint of obtaining a thin glass having a thickness in the range of 10 to 50 μm.
　通常、ガラスの厚さが薄いほど、ガラスの強度は低下し、破損しやすくなるため、薄膜ガラスの単体での取り扱いや加工は難しい。しかし、薄膜ガラスをより厚い支持基板（以下、「キャリア基板」ともいう。）に一時的に接着しながら加工し、加工の後工程として支持基板を剥離することにより、薄膜ガラスの取り扱いや加工を容易化できる。 Normally, the thinner the glass, the weaker it is and the more susceptible it is to breakage, making it difficult to handle and process thin-film glass on its own. However, by processing the thin-film glass while temporarily adhering it to a thicker support substrate (hereafter also referred to as a "carrier substrate"), and then peeling off the support substrate as a post-processing step, it is possible to make the thin-film glass easier to handle and process.
　例えば、国際公開第２０１７／０６６９２４号に記載の技術では、厚さが１００μｍ未満のソーダライムガラスは、下記の工程によって作製できる。なお、図４は、薄膜ガラスの作製方法の一例を示す模式図である。 For example, in the technology described in International Publication No. 2017/066924, soda-lime glass having a thickness of less than 100 μm can be produced by the following process. Note that FIG. 4 is a schematic diagram showing an example of a method for producing thin-film glass.
　（工程１）
　図４に示すように、工程１では、接合面を有するキャリア基板２１上に、薄膜ガラスの第１の表面が接するように薄膜ガラス２２を作製する。そして、上記第１の表面とは反対側の第２の表面に、接着力を有するコンタクト膜２３（「コンタクトフィルム」ともいう。）を圧着させる。 (Step 1)
4, in step 1, a thin film glass 22 is prepared so that a first surface of the thin film glass is in contact with a carrier substrate 21 having a bonding surface. Then, a contact film 23 (also called a "contact film") having adhesive force is pressure-bonded to a second surface opposite to the first surface.
　すなわち、十分な強度と加工しやすい厚さを有するキャリア基板２１上に、薄膜ガラスの材料を、所望の厚さになるよう流し込む。これにより、薄膜ガラス２２の第１の表面が、キャリア基板２１に接するように作製される。その後、上記第１の表面とは反対側の第２の表面にコンタクト膜２３を圧着させる。 That is, the thin-film glass material is poured to the desired thickness onto a carrier substrate 21 that has sufficient strength and a thickness that is easy to process. This creates a first surface of the thin-film glass 22 that is in contact with the carrier substrate 21. After that, a contact film 23 is pressed onto a second surface on the opposite side to the first surface.
　（工程２）
　図４に示すように、工程２では、薄膜ガラス２２を接着力の高いコンタクト膜２３によって、キャリア基板２１から剥離する。 (Step 2)
As shown in FIG. 4, in step 2, the thin glass 22 is peeled off from the carrier substrate 21 by the contact film 23 having high adhesive strength.
　（工程３）
　図４に示すように、工程３では、コンタクト膜の接着力を弱める脆弱化処理（電磁放射線照射２４）を行う。これにより、薄膜ガラス２２の第２の表面から、コンタクト膜２３を除去する。 (Step 3)
4, in step 3, a weakening treatment (electromagnetic radiation irradiation 24) is performed to weaken the adhesive strength of the contact film, thereby removing the contact film 23 from the second surface of the thin glass 22.
　このように、薄膜ガラス２２を安全に保持するためのコンタクト膜２３を使用することにより、薄膜ガラス２２を保護することができる。薄膜ガラス２２の露出した表面を、例えば、機械的損傷から保護することができ、安全かつ簡便に取り扱うことができる。 In this way, the contact film 23 is used to safely hold the thin-film glass 22, thereby protecting the thin-film glass 22. The exposed surface of the thin-film glass 22 can be protected from, for example, mechanical damage, and can be handled safely and easily.
　コンタクト膜の材料としては、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレン（ＰＥ）等のポリオレフィン（ＰＯ）が挙げられる。 Examples of materials for the contact film include polyolefins (PO) such as polyethylene terephthalate (PET) and polyethylene (PE).
　コンタクト膜は、通常、基材の一方の面に設けられた接着剤からなる接着剤層によって、薄膜ガラスに接着されている。コンタクト膜は、コンタクト膜自体が有する接着性によって直接薄膜ガラスに接着されていてもよい。 The contact film is usually adhered to the thin glass by an adhesive layer made of an adhesive provided on one side of the substrate. The contact film may also be adhered directly to the thin glass by the adhesive properties of the contact film itself.
　コンタクト膜と薄膜ガラスの第２の表面との間の接着力は、剥離装置により、キャリア基板から薄膜ガラスを剥離するのに十分な力が伝達されるよう、適宜選択される。 The adhesive strength between the contact film and the second surface of the thin film glass is appropriately selected so that the peeling device transmits sufficient force to peel the thin film glass from the carrier substrate.
　コンタクト膜の形状は、箔又はテープとすることが好ましい。箔又はテープとすることにより、ロール状に巻き取ることができる。コンタクト膜の厚さは、５０μｍ以上であることが好ましく、８０μｍ以上であることが好ましく、１２５μｍ以上であることがより好ましく、１５０μｍ以上であることが特に好ましい。 The contact film is preferably in the form of a foil or tape. By forming it into a foil or tape, it can be wound into a roll. The thickness of the contact film is preferably 50 μm or more, more preferably 80 μm or more, more preferably 125 μm or more, and particularly preferably 150 μm or more.
　薄膜ガラスは、前述のダウンドロー法、オーバーフローダウンドロー法、又はフロート法等によって、キャリア基板上に作製されることが好ましい。 The thin glass is preferably fabricated on a carrier substrate by the aforementioned downdraw method, overflow downdraw method, or float method.
　キャリア基板の厚さは、１００μｍ以上であることが好ましく、３００μｍ以上であることがより好ましく、５００μｍ以上であることが更に好ましい。
　また、キャリア基板の幅手方向の長さは、３インチ（１インチは２．５４ｃｍ）以上であることが好ましく、６インチ以上であることがより好ましく、８インチ以上であることが更に好ましく、１２インチ以上であることが特に好ましい。 The thickness of the carrier substrate is preferably 100 μm or more, more preferably 300 μm or more, and even more preferably 500 μm or more.
Furthermore, the width of the carrier substrate is preferably 3 inches or more (1 inch is 2.54 cm), more preferably 6 inches or more, even more preferably 8 inches or more, and particularly preferably 12 inches or more.
　特に、キャリア基板は、ガラス基板第一世代サイズ以上であることが好ましく、例えば第二世代～第八世代のサイズであることが好ましい。または、例えば１×１ｍ～３×３ｍの更に大きいサイズとしてもよい。キャリア基板は、長方形、楕円形、円形等の様々な形状としてもよい。 In particular, the carrier substrate is preferably equal to or larger than the first generation glass substrate size, for example, second to eighth generation sizes. Alternatively, it may be even larger, for example, 1x1m to 3x3m. The carrier substrate may be of various shapes, such as rectangular, elliptical, circular, etc.
　薄膜ガラスは、コンタクト膜と共に、コンタクト膜の接着力によってキャリア基板から剥離される。その後、コンタクト膜が剥離され、薄膜ガラスの単体が得られる。 The thin glass film, together with the contact film, is peeled off from the carrier substrate by the adhesive force of the contact film. The contact film is then peeled off, leaving a single thin glass film.
　薄膜ガラスからコンタクト膜を剥離する前に、コンタクト膜に対して接着力の脆弱化処理を施すことにより、接着力を低下させることが好ましい。具体的には、接着力を０．５Ｎ／２５ｍｍ以下に低下させることが好ましい。 Before peeling the contact film from the thin glass, it is preferable to weaken the adhesive strength of the contact film by subjecting it to a treatment to weaken its adhesive strength. Specifically, it is preferable to reduce the adhesive strength to 0.5 N/25 mm or less.
　脆弱化処理では、例えば赤外線、紫外線、可視光等の電磁放射線を適宜用いることが好ましい。電磁放射線は、使用される接着材料に対応して、狭帯域であってもよく、より広い帯域をカバーしてもよい。また、レーザー放射であってもよい。 In the weakening process, it is preferable to use electromagnetic radiation, such as infrared, ultraviolet, or visible light, as appropriate. The electromagnetic radiation may be narrowband or may cover a wider band depending on the adhesive material used. It may also be laser radiation.
　中でも、可視光の曝露の下で接着力が劣化しないよう、可視スペクトルの外側の波長を有する電磁放射線を選択することが好ましい。市販されている接着材料の中には、電磁放射線の照射によって、少なくとも部分的に非活性化することができるものがあり、このような接着材料をコンタクト膜として使用できる。 It is preferable to select electromagnetic radiation having a wavelength outside the visible spectrum so that the adhesive strength does not deteriorate under exposure to visible light. Some commercially available adhesive materials can be at least partially deactivated by exposure to electromagnetic radiation and can be used as contact films.
　温度を上昇又は下降させることにより、コンタクト膜の接着性が低下する場合には、脆弱化処理として熱処理を用いてもよい。 If increasing or decreasing the temperature reduces the adhesion of the contact film, heat treatment may be used as a weakening treatment.
　電磁放射線の照射は、コンタクト膜の外側の面から、すなわち薄膜ガラスが接着していない側の面から行われることが好ましい。 The electromagnetic radiation is preferably applied from the outer surface of the contact film, i.e., the side to which the thin glass is not adhered.
　コンタクト膜としては、例えば、「ＮＤＳ４１５０－２０」（道明光学股▲ふん▼有限公司製）等が挙げられる。これに対応する脆弱化処理は、波長３６５ｎｍの紫外線照射が挙げられる。 An example of a contact film is "NDS4150-20" (manufactured by Dao Ming Optical Co., Ltd.). A corresponding weakening treatment is exposure to ultraviolet light with a wavelength of 365 nm.
　具体的な薄膜ガラスの作製方法や条件については、実施例の項にて説明する。また、薄膜ガラスとして、例えば、ＳＣＨＯＴＴ社製、日本電気硝子株式会社製等の市販品を用い
ることができる。 Specific methods and conditions for producing the thin film glass will be described in the Examples section. As the thin film glass, for example, commercially available products manufactured by SCHOTT Co., Ltd., Nippon Electric Glass Co., Ltd., etc. can be used.
　（３）粘着層
　（３．１）粘着層の概要
　本発明において、「粘着層」とは、カバーユニットを表示ユニットに取り付ける、又は積層体における各層を貼り合わせるのに十分な程度の粘着性を有した層のことをいう。また、粘着層Ｃ及び粘着層Ｄをまとめた総称とする。
　なお、粘着層Ｃ及び粘着層Ｄを構成する材料は、同一であっても、同一でなくてもよい。粘着層は、粘着剤で作製されることが好ましい。
　以下、好適に用いられる粘着剤について説明する。 (3) Adhesive Layer (3.1) Overview of Adhesive Layer In the present invention, the term "adhesive layer" refers to a layer having sufficient adhesiveness to attach the cover unit to the display unit or to bond each layer in the laminate. It is also a general term for adhesive layer C and adhesive layer D.
The materials constituting the adhesive layer C and the adhesive layer D may or may not be the same. The adhesive layer is preferably made of an adhesive.
The adhesive that is preferably used will be described below.
　本発明に係る粘着層は、フィルムのように巻き取れる形状であっても、塗布層の形状であってもよい。塗布層は、隣接する層上に、粘着剤を塗布した後、硬化することにより形成される。 The adhesive layer according to the present invention may be in the form of a film that can be rolled up, or in the form of a coating layer. The coating layer is formed by applying an adhesive onto an adjacent layer and then curing the applied adhesive.
　粘着剤は、特に制限されず、例えば、ゴム系粘着剤、アクリル系粘着剤、シリコーン系粘着剤、ウレタン系粘着剤、ビニルアルキルエーテル系粘着剤、ポリビニルアルコール系粘着剤、ポリビニルピロリドン系粘着剤、ポリアクリルアミド系粘着剤、セルロース系粘着剤等が挙げられる。中でも、アクリル系粘着剤であることが好ましい。アクリル系粘着剤は、透明性に優れ、粘着特性（密着性、凝集性及び接着性）に優れる。また、耐候性、耐熱性等にも優れる。
　なお、ここでの、「アクリル系粘着剤」とは、アクリル系ポリマーをベースポリマーとして含有する粘着剤のことをいう。 The adhesive is not particularly limited, and examples thereof include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these, acrylic-based adhesives are preferred. Acrylic-based adhesives are excellent in transparency and adhesive properties (adhesion, cohesion, and adhesion). They are also excellent in weather resistance, heat resistance, and the like.
Here, the term "acrylic pressure-sensitive adhesive" refers to a pressure-sensitive adhesive that contains an acrylic polymer as a base polymer.
　（３．２）粘着層Ｃ
　本発明の積層体は、更に粘着層Ｃを有することが好ましい。
　粘着層Ｃを有する場合、各層は、図２に示すように、光学フィルムＡ、ガラス層、光学フィルムＢ、粘着層Ｃの順で配置されることが好ましい。
　また、光学フィルムＢ及び粘着層Ｃの３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＢ及びＴＣとしたとき、ＴＢ及びＴＣが、下記式（２）を満たすことが好ましい。
　式（２）：　ＴＢ＜ＴＣ (3.2) Adhesive layer C
The laminate of the present invention preferably further comprises an adhesive layer C.
When the adhesive layer C is provided, the layers are preferably arranged in the order of the optical film A, the glass layer, the optical film B, and the adhesive layer C, as shown in FIG.
In addition, when the average light transmittances in the wavelength region of 380 to 780 nm of the optical film B and the adhesive layer C are T B and T C , respectively, it is preferable that T B and T C satisfy the following formula (2).
Equation (2): TB < TC
　積層体の最も表示装置側に更に粘着層Ｃを有することにより、当該積層体を表示装置に取り付けることができる。 By further providing an adhesive layer C on the side of the laminate closest to the display device, the laminate can be attached to the display device.
　前述のとおり、カバーユニットを取り付けた表示装置に対してペン入力を行うと、光学フィルムＡ側から、ペン入力を行うことになる。このとき、光学フィルムＢが、薄膜ガラスの裏面（視認側に近い方の面を表面としたときの裏面）に働く外側への引張応力を抑制できれば、薄膜ガラスがたわんで破損するのを防止（耐衝撃性）できる。ここで、光学フィルムＢに隣接して更に粘着層Ｃを配置することにより、薄膜ガラスの裏面に働く外側への引張応力を、更に抑制できると考えられる。 As mentioned above, when pen input is performed on a display device with a cover unit attached, the pen input is performed from the optical film A side. At this time, if optical film B can suppress the outward tensile stress acting on the back surface of the thin film glass (the back surface when the surface closer to the viewing side is considered the front surface), it is possible to prevent the thin film glass from bending and breaking (impact resistance). Here, it is believed that by further arranging adhesive layer C adjacent to optical film B, the outward tensile stress acting on the back surface of the thin film glass can be further suppressed.
　粘着層Ｃについても、光学フィルムと同様、着色剤を含有させることにより、光透過率を調整できる。ただし、場合によっては、着色剤を含有させることにより粘着力が低下してしまう。このため、着色剤を含有させる場合には、所望の粘着力が得られるよう、適宜材料及び含有量を選択することが好ましい。粘着層Ｃが、十分な粘着力を有することにより、繰り返し折り曲げを行った後の表示装置においても、カバーユニットと表示ユニットとの剥離を抑制できる。そして、剥離を抑制できることにより、耐衝撃性及び良好なコントラストを維持できると考えられる。 As with the optical film, the adhesive layer C can also contain a colorant to adjust the light transmittance. However, in some cases, the inclusion of a colorant can reduce the adhesive strength. For this reason, when a colorant is contained, it is preferable to select the material and content appropriately so as to obtain the desired adhesive strength. By providing the adhesive layer C with sufficient adhesive strength, peeling between the cover unit and the display unit can be suppressed even in a display device that has been repeatedly bent. Furthermore, it is believed that being able to suppress peeling makes it possible to maintain impact resistance and good contrast.
　（３．３）粘着層Ｄ
　本発明の積層体は、更に粘着層Ｄを有することが好ましい。
　粘着層Ｄを有する場合、各層は、光学フィルムＡ、ガラス層、粘着層Ｄ、光学フィルムＢの順で配置されることが好ましい。加えて粘着層Ｃを有する場合、各層は、図３に示すように、光学フィルムＡ、ガラス層、粘着層Ｄ、光学フィルムＢ、粘着層Ｃの順で配置されることが好ましい。 (3.3) Adhesive layer D
The laminate of the present invention preferably further comprises an adhesive layer D.
When the adhesive layer D is included, the layers are preferably arranged in the order of the optical film A, the glass layer, the adhesive layer D, and the optical film B. In addition, when the adhesive layer C is included, the layers are preferably arranged in the order of the optical film A, the glass layer, the adhesive layer D, the optical film B, and the adhesive layer C, as shown in FIG.
　また、粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内であることが好ましい。 In addition, it is preferable that the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
　ガラス層と光学フィルムＢとの間に更に粘着層Ｄを有することにより、ガラス層と光学フィルムＢの密着性を高めることができる。 By further providing an adhesive layer D between the glass layer and the optical film B, the adhesion between the glass layer and the optical film B can be improved.
　前述のとおり、カバーユニットを取り付けた表示装置に対してペン入力を行うと、光学フィルムＡ側から、ペン入力を行うことになる。このとき、薄膜ガラスの裏面（視認側に近い方の面を表面としたときの裏面）に働く外側への引張応力を抑制できれば、薄膜ガラスがたわんで破損するのを防止（耐衝撃性）できる。ここで、ガラス層と光学フィルムＢとの間に更に粘着層を配置することにより、薄膜ガラスの裏面に働く外側への引張応力を、更に抑制できると考えられる。 As mentioned above, when pen input is performed on a display device with a cover unit attached, the pen input is performed from the optical film A side. At this time, if the outward tensile stress acting on the back surface of the thin film glass (the back surface when the surface closer to the viewing side is considered the front surface) can be suppressed, it is possible to prevent the thin film glass from bending and breaking (impact resistance). Here, it is believed that by further disposing an adhesive layer between the glass layer and optical film B, the outward tensile stress acting on the back surface of the thin film glass can be further suppressed.
　粘着層Ｄの貯蔵弾性率を特定の範囲内とする、すなわち、粘着層Ｄを適度に柔らかくすることにより、良好な耐衝撃性が得られると考えられる。 It is believed that good impact resistance can be obtained by setting the storage modulus of the adhesive layer D within a specific range, i.e., by making the adhesive layer D appropriately soft.
　（３．４）粘着層（紫外線硬化型アクリル系粘着剤）の成分構成
　アクリル系粘着剤で作製される粘着層としては、例えば、紫外線硬化型アクリル系粘着剤を紫外線硬化（紫外線重合）することにより形成される層であることが好ましい。なお、紫外線硬化型アクリル系粘着剤を紫外線硬化（紫外線重合）することにより、（メタ）アクリル系ポリマーが生成する。 (3.4) Component composition of adhesive layer (ultraviolet-curable acrylic adhesive) The adhesive layer made of an acrylic adhesive is preferably a layer formed by, for example, ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive. Note that, by ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive, a (meth)acrylic polymer is generated.
　「紫外線硬化型アクリル系粘着剤」とは、アルキル（メタ）アクリレートを含有するモノマー成分又は当該モノマー成分の部分重合物、光重合開始剤等を含有することが好ましい。 The "ultraviolet-curable acrylic adhesive" preferably contains a monomer component containing alkyl (meth)acrylate or a partial polymer of the monomer component, a photopolymerization initiator, etc.
　粘着層の光透過率を適宜調整することにより、粘着層にも、偏光板の一部の機能を付与でき、具体的には、外光反射を更に抑制できる。また、積層体を表示装置のカバーガラスユニットとして使用した際に、十分なコントラストが得られる。
　光透過率は、粘着層（紫外線硬化型アクリル系粘着剤）に、着色剤を含有させることにより調整できる。着色剤は、光学フィルムと同様のものを使用できる。
　着色剤の含有量は、粘着層の全質量に対して、１．０２質量％以下であることが好ましい。 By appropriately adjusting the light transmittance of the adhesive layer, the adhesive layer can also be given a part of the function of a polarizing plate, specifically, the reflection of external light can be further suppressed. Furthermore, when the laminate is used as a cover glass unit of a display device, sufficient contrast can be obtained.
The light transmittance can be adjusted by adding a colorant to the adhesive layer (ultraviolet-curable acrylic adhesive). The colorant may be the same as that used in the optical film.
The content of the colorant is preferably 1.02 mass % or less based on the total mass of the adhesive layer.
　（３．４．１）モノマー成分
　紫外線硬化型アクリル系粘着剤は、アクリレートを含有するモノマー成分又は当該モノマー成分の部分重合物を、紫外線硬化（紫外線重合）することにより得られる（メタ）アクリル系ポリマーをベースポリマーとする。
　以下、モノマー成分に含有されるアルキル（メタ）アクリレートと、その他含有してもよいモノマーについて説明する。その他含有してもよいモノマーとしては、単官能性モノマーであることが好ましいが、多官能性モノマーであってもよい。 (3.4.1) Monomer Component The UV-curable acrylic pressure-sensitive adhesive has as its base polymer a (meth)acrylic polymer obtained by UV-curing (UV-polymerizing) a monomer component containing an acrylate or a partial polymer of the monomer component.
The alkyl (meth)acrylate contained in the monomer component and other monomers that may be contained will be described below. The other monomers that may be contained are preferably monofunctional monomers, but may also be polyfunctional monomers.
　（３．４．１．１）アルキル（メタ）アクリレート
　本発明において、「（メタ）アクリル」とは、アクリル及びメタクリルのことをいい、その総称である。また、「アルキル（メタ）アクリレート」とは、アルキルアクリレート及びアルキルメタクリレートのことをいい、その総称である。
　本発明に係るアルキル（メタ）アクリレートは、直鎖状又は分枝鎖状の炭素数１～２４のアルキル基を、エステル末端に有するアルキル（メタ）アクリレートであることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 (3.4.1.1) Alkyl (meth)acrylate In the present invention, "(meth)acrylic" refers to acrylic and methacrylic, and is a general term for both. Also, "alkyl (meth)acrylate" refers to alkyl acrylate and alkyl methacrylate, and is a general term for both.
The alkyl (meth)acrylate according to the present invention is preferably an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal.
These may be used alone or in combination of two or more.
　アルキル（メタ）アクリレートとしては、例えば、炭素数４～９の分枝鎖状のアルキル基を有するアルキル（メタ）アクリレートが挙げられる。具体的には、ｎ－ブチル（メタ）アクリレート、ｓｅｃ－ブチル（メタ）アクリレート、ｔｅｒｔ－ブチル（メタ）アクリレート、イソブチル（メタ）アクリレート、ｎ－ペンチル（メタ）アクリレート、イソペンチル（メタ）アクリレート、イソヘキシル（メタ）アクリレート、イソヘプチル（メタ）アクリレート、２－エチルヘキシル（メタ）アクリレート、イソオクチル（メタ）アクリレート、イソノニル（メタ）アクリレート等が挙げられる。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of alkyl (meth)acrylates include alkyl (meth)acrylates having a branched alkyl group having 4 to 9 carbon atoms. Specific examples include n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and isononyl (meth)acrylate.
These may be used alone or in combination of two or more.
　炭素数１～２４のアルキル基をエステル末端に有するアルキル（メタ）アクリレートの含有量は、モノマー成分の全質量に対して、４０質量％以上であることが好ましい。また、５０質量％以上であることがより好ましく、６０質量％以上であることが更に好ましい。 The content of alkyl (meth)acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the monomer components.
　（３．４．１．２）その他のモノマー成分
　アルキル（メタ）アクリレート以外の単官能の共重合モノマー（単官能性モノマー）としては、例えば、環状窒素含有モノマーが挙げられる。環状窒素含有モノマーとしては、（メタ）アクリロイル基又はビニル基等の不飽和二重結合を有する重合性の官能基を有し、かつ環状窒素構造を有するものであれば、特に制限されない。なお、環状窒素構造は、環状構造内に窒素原子を有するものが好ましい。 (3.4.1.2) Other Monomer Components Examples of monofunctional copolymerizable monomers (monofunctional monomers) other than alkyl (meth)acrylates include cyclic nitrogen-containing monomers. The cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure. The cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure.
　環状窒素含有モノマーとしては、例えば、Ｎ－ビニル－２－ピロリドン、Ｎ－ビニル－ε－カプロラクタム、メチルビニルピロリドン等のラクタム系ビニルモノマー；ビニルピリジン、ビニルピペリドン、ビニルピリミジン、ビニルピペラジン、ビニルピラジン、ビニルピロール、ビニルイミダゾール、ビニルオキサゾール、ビニルモルホリン等の窒素含有複素環を有するビニル系モノマー等が挙げられる。また、モルホリン環、ピペリジン環、ピロリジン環、ピペラジン環等の複素環を含有する（メタ）アクリルモノマーが挙げられる。
　具体的には、Ｎ－アクリロイルモルホリン、Ｎ－アクリロイルピペリジン、Ｎ－メタクリロイルピペリジン、Ｎ－アクリロイルピロリジン等が挙げられる。
　中でも、ラクタム系ビニルモノマーであることが好ましい。 Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone, and vinyl-based monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. Also included are (meth)acrylic monomers containing a heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.
Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.
Among these, lactam vinyl monomers are preferred.
　環状窒素含有モノマーの含有量は、モノマー成分の全質量に対して、０．５～５０質量％であることが好ましく、０．５～４０質量％であることがより好ましく、０．５～３０質量％であることが更に好ましい。 The content of the cyclic nitrogen-containing monomer is preferably 0.5 to 50 mass%, more preferably 0.5 to 40 mass%, and even more preferably 0.5 to 30 mass%, based on the total mass of the monomer components.
　また、単官能性モノマーとしては、ヒドロキシ基含有モノマーが挙げられる。ヒドロキシ基含有モノマーとしては、（メタ）アクリロイル基又はビニル基等の不飽和二重結合を有する重合性の官能基を有し、かつヒドロキシ基を有するものであれば、特に制限されない。 Another example of a monofunctional monomer is a hydroxyl group-containing monomer. There are no particular limitations on the hydroxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a hydroxyl group.
　ヒドロキシ基含有モノマーとしては、例えば、２－ヒドロキシエチル（メタ）アクリレート、２－ヒドロキシプロピル（メタ）アクリレート、２－ヒドロキシブチル（メタ）アクリレート、３－ヒドロキシプロピル（メタ）アクリレート、４－ヒドロキシブチル（メタ）アクリレート、６－ヒドロキシヘキシル（メタ）アクリレート、８－ヒドロキシオクチル（メタ）アクリレート、１０－ヒドロキシデシル（メタ）アクリレート、１２－ヒドロキシラウリル（メタ）アクリレート等のヒドロキシアルキル（メタ）アクリレート；（４－ヒドロキシメチルシクロへキシル）メチル（メタ）アクリレート等のヒドロキシアルキルシクロアルカン（メタ）アクリレート等が挙げられる。その他、ヒドロキシエチル（メタ）アクリルアミド、アリルアルコール、２－ヒドロキシエチルビニルエーテル、４－ヒドロキシブチルビニルエーテル、ジエチレングリコールモノビニルエーテル等が挙げられる。中でも、ヒドロキシアルキル（メタ）アクリレートであることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of the hydroxy group-containing monomer include hydroxyalkyl (meth)acrylates such as 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, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Other examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. Among these, hydroxyalkyl (meth)acrylates are preferred.
These may be used alone or in combination of two or more.
　ヒドロキシ基含有モノマーの含有量は、モノマー成分の全質量に対して、１～３０質量％の範囲内であることが好ましく、２～２７質量％の範囲内であることがより好ましく、３～２５質量％の範囲内であることが更に好ましい。上記範囲内であることにより、粘着層の接着力の低下を抑制できる。また、得られる粘着剤の粘度の上昇やゲル化を抑制できる。 The content of the hydroxyl group-containing monomer is preferably within the range of 1 to 30% by mass, more preferably within the range of 2 to 27% by mass, and even more preferably within the range of 3 to 25% by mass, based on the total mass of the monomer components. By keeping the content within the above range, it is possible to suppress a decrease in the adhesive strength of the adhesive layer. In addition, it is possible to suppress an increase in the viscosity and gelation of the resulting adhesive.
　単官能性モノマーとしては、その他、例えば、カルボキシ基含有モノマー、環状エーテル基を有するモノマー等が挙げられる。 Other examples of monofunctional monomers include carboxyl group-containing monomers and monomers having cyclic ether groups.
　カルボキシ基含有モノマーとしては、（メタ）アクリロイル基又はビニル基等の不飽和二重結合を有する重合性の官能基を有し、かつカルボキシ基を有するものであれば、特に制限されない。 There are no particular limitations on the carboxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a carboxyl group.
　カルボキシ基含有モノマーとしては、例えば、（メタ）アクリル酸、カルボキシエチル（メタ）アクリレート、カルボキシペンチル（メタ）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、イソクロトン酸等が挙げられる。また、イタコン酸又はマレイン酸は、これらの無水物であってもよい。
　中でも、アクリル酸又はメタクリル酸であることが好ましく、アクリル酸であることがより好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of the carboxy group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. In addition, itaconic acid or maleic acid may be an anhydride thereof.
Of these, acrylic acid or methacrylic acid is preferred, and acrylic acid is more preferred.
These may be used alone or in combination of two or more.
　環状エーテル基を有するモノマーとしては、（メタ）アクリロイル基又はビニル基等の不飽和二重結合を有する重合性の官能基を有し、かつエポキシ基又はオキセタン基等の環状エーテル基を有するものであれば、特に制限されない。 The monomer having a cyclic ether group is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a cyclic ether group, such as an epoxy group or an oxetane group.
　エポキシ基含有モノマーとしては、例えば、グリシジル（メタ）アクリレート、３，４－エポキシシクロヘキシルメチル（メタ）アクリレート、４－ヒドロキシブチル（メタ）アクリレートグリシジルエーテル等が挙げられる。オキセタン基含有モノマーとしては、例えば、３－オキセタニルメチル（メタ）アクリレート、３－メチル－オキセタニルメチル（メタ）アクリレート、３－エチル－オキセタニルメチル（メタ）アクリレート、３－ブチル－オキセタニルメチル（メタ）アクリレート、３－ヘキシル－オキセタニルメチル（メタ）アクリレート、等が挙げられる。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. Examples of oxetane group-containing monomers include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc.
These may be used alone or in combination of two or more.
　カルボキシ基含有モノマー又は環状エーテル基を有するモノマーの含有量は、モノマー成分の全質量に対して、３０質量％以下であることが好ましく、２７質量％以下であることがより好ましく、２５質量％以下であることが更に好ましい。 The content of the carboxyl group-containing monomer or the monomer having a cyclic ether group is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, based on the total mass of the monomer components.
　その他の単官能性モノマーとしては、例えば、ＣＨ２＝Ｃ（Ｒ１）ＣＯＯＲ２（Ｒ１は水素原子又はメチル基を表し、Ｒ２は炭素数１～３の置換されたアルキル基、又は環状のシクロアルキル基を表す。）で表されるアルキル（メタ）アクリレートが挙げられる。 Other monofunctional monomers include, for example, alkyl (meth)acrylates represented by CH 2 ═C(R 1 )COOR 2 (R 1 represents a hydrogen atom or a methyl group, and R 2 represents a substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group).
　上記ＣＨ２＝Ｃ（Ｒ１）ＣＯＯＲ２で表されるアルキル（メタ）アクリレートとしては、例えば、フェノキシエチル（メタ）アクリレート、ベンジル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、３，３，５－トリメチルシクロヘキシル（メタ）アクリレート、イソボルニル（メタ）アクリレート等が挙げられる。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of the alkyl (meth)acrylate represented by CH 2 ═C(R 1 )COOR 2 include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate.
These may be used alone or in combination of two or more.
　上記ＣＨ２＝Ｃ（Ｒ１）ＣＯＯＲ２で表されるアルキル（メタ）アクリレートの含有量は、モノマー成分の全質量に対して、５０質量％以下であることが好ましく、４５質量％以下であることがより好ましく、４０質量％以下であることが更に好ましい。 The content of the alkyl (meth)acrylate represented by the above CH 2 ═C(R 1 )COOR 2 is preferably 50 mass% or less, more preferably 45 mass% or less, and even more preferably 40 mass% or less, based on the total mass of the monomer components.
　また、その他の単官能性モノマーとしては、例えば、酢酸ビニル、プロピオン酸ビニル、スチレン、α－メチルスチレン；（メタ）アクリル酸ポリエチレングリコール、（メタ）アクリル酸ポリプロピレングリコール、（メタ）アクリル酸メトキシエチレングリコール、（メタ）アクリル酸メトキシポリプロピレングリコール等のグリコール系アクリルエステルモノマー；（メタ）アクリル酸テトラヒドロフルフリル、フッ素（メタ）アクリレート、シリコーン（メタ）アクリレート、２－メトキシエチルアクリレート等のアクリル酸エステル系モノマー；アミド基含有モノマー、アミノ基含有モノマー、イミド基含有モノマー、Ｎ－アクリロイルモルホリン、ビニルエーテルモノマー等が挙げられる。また、テルペン（メタ）アクリレート、ジシクロペンタニル（メタ）アクリレート等の環状構造を有するモノマーが挙げられる。 Other monofunctional monomers include, for example, vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Also included are monomers having a cyclic structure such as terpene (meth)acrylate and dicyclopentanyl (meth)acrylate.
　さらに、その他の単官能性モノマーとしては、ケイ素原子を含有するシラン系モノマー等が挙げられる。
　シラン系モノマーとしては、例えば、３－アクリロキシプロピルトリエトキシシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、４－ビニルブチルトリメトキシシラン、４－ビニルブチルトリエトキシシラン、８－ビニルオクチルトリメトキシシラン、８－ビニルオクチルトリエトキシシラン、１０－メタクリロイルオキシデシルトリメトキシシラン、１０－アクリロイルオキシデシルトリメトキシシラン、１０－メタクリロイルオキシデシルトリエトキシシラン、１０－アクリロイルオキシデシルトリエトキシシラン等が挙げられる。 Further, other monofunctional monomers include silane-based monomers containing a silicon atom.
Examples of silane monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.
　その他のモノマーとしては、上記で例示した単官能性モノマーの他に、粘着層の凝集力を調整する観点から、必要に応じて多官能性モノマーを含有してもよい。 In addition to the monofunctional monomers exemplified above, other monomers may contain polyfunctional monomers as necessary in order to adjust the cohesive strength of the adhesive layer.
　多官能性モノマーは、（メタ）アクリロイル基又はビニル基等の不飽和二重結合を有する重合性の官能基を少なくとも２つ有するモノマーであれば、特に制限されない。 There are no particular limitations on the polyfunctional monomer, so long as it is a monomer that has at least two polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl groups or vinyl groups.
　多官能性モノマーとしては、例えば、（ポリ）エチレングリコールジ（メタ）アクリレート、（ポリ）プロピレングリコールジ（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、ペンタエリスリトールジ（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、ジペンタエリスリトールヘキサ（メタ）アクリレート、１，２－エチレングリコールジ（メタ）アクリレート、１，６－ヘキサンジオールジ（メタ）アクリレート、１，１２－ドデカンジオールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、テトラメチロールメタントリ（メタ）アクリレート等の多価アルコールと（メタ）アクリル酸とのエステル化合物；アリル（メタ）アクリレート、ビニル（メタ）アクリレート、ジビニルベンゼン、エポキシアクリレート、ポリエステルアクリレート、ウレタンアクリレート、ブチルジ（メタ）アクリレート、ヘキシルジ（メタ）アクリレート等が挙げられる。 Examples of polyfunctional monomers include ester compounds of polyhydric alcohols and (meth)acrylic acid such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate.
　中でも、トリメチロールプロパントリ（メタ）アクリレート、ヘキサンジオールジ（メタ）アクリレート、又はジペンタエリスリトールヘキサ（メタ）アクリレートであることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 Of these, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate is preferred.
These may be used alone or in combination of two or more.
　多官能性モノマーの含有量は、分子量や官能基数等により異なるが、単官能性モノマーの全質量に対して、３質量％以下であることが好ましく、２質量％以下であることがより好ましく、１質量％以下であることが更に好ましい。また、多官能性モノマーの含有量は、０．００１質量％以上であることが好ましい。上記範囲内であることにより、粘着層の接着力を向上できる。 The content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, etc., but is preferably 3 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less, relative to the total mass of the monofunctional monomer. In addition, the content of the polyfunctional monomer is preferably 0.001 mass% or more. By being within the above range, the adhesive strength of the adhesive layer can be improved.
　モノマー成分においては、上記モノマー成分の部分重合物が含有されていてもよい。 The monomer component may contain a partial polymer of the above monomer component.
　（３．４．２）光重合開始剤
　本発明に係る紫外線硬化型アクリル系粘着剤は、光重合開始剤を含有することが好ましい。
　光重合開始剤を含有することにより、上記モノマー成分を、十分に重合することができる。 (3.4.2) Photopolymerization initiator The ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention preferably contains a photopolymerization initiator.
By including a photopolymerization initiator, the monomer components can be polymerized sufficiently.
　光重合開始剤は、紫外線によりラジカルを発生し、光重合を開始するものであれば、特に制限されず、通常用いられる光重合開始剤を好適に用いることができる。例えば、ベンゾインエーテル系光重合開始剤、アセトフェノン系光重合開始剤、α－ケトール系光重合開始剤、光活性オキシム系光重合開始剤、ベンゾイン系光重合開始剤、ベンジル系光重合開始剤、ベンゾフェノン系光重合開始剤、ケタール系光重合開始剤、チオキサントン系光重合開始剤、アシルフォスフィンオキサイド系光重合開始剤等が挙げられる。 The photopolymerization initiator is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization, and any commonly used photopolymerization initiator can be suitably used. Examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.
　また、ビス（２，４，６－トリメチルベンゾイル）－フェニルフォスフィンオキサイド（市販品は、例えば、「Ｏｍｎｉｒａｄ（登録商標）８１９」（ＩＧＭ　Ｒｅｓｉｎｓ　Ｂ．Ｖ．社製））、２，４，６－トリメチルベンゾイル－ジフェニル－フォスフィンオキサイド（市販品は、例えば、「Ｏｍｎｉｒａｄ（登録商標）ＴＰＯ　Ｈ」（ＩＧＭ　Ｒｅｓｉｎｓ　Ｂ．Ｖ．製））等が挙げられる。
　これらは、一種単独で用いても、二種以上併用してもよい。 Further examples thereof include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) 819" (manufactured by IGM Resins B.V.)), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) TPO H" (manufactured by IGM Resins B.V.)), and the like.
These may be used alone or in combination of two or more.
　光重合開始剤の含有量は、モノマー成分の全質量に対して、０．００５～０．５質量％の範囲内であることが好ましく、０．０２～０．１質量％の範囲内であることがより好ましい。上記範囲内であることにより、紫外線硬化（紫外線重合）を十分に進行させることができる。 The content of the photopolymerization initiator is preferably within the range of 0.005 to 0.5% by mass, and more preferably within the range of 0.02 to 0.1% by mass, based on the total mass of the monomer components. By being within the above range, ultraviolet curing (ultraviolet polymerization) can proceed sufficiently.
　（３．４．３）その他
　本発明に係る紫外線硬化型アクリル系粘着剤は、更にシランカップリング剤、架橋剤等を含有してもよい。 (3.4.3) Others The ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention may further contain a silane coupling agent, a crosslinking agent, and the like.
　シランカップリング剤としては、例えば、３－グリシドキシプロピルトリメトキシシラン、３－グリシドキシプロピルトリエトキシシラン、３－グリシドキシプロピルメチルジエトキシシラン、２－（３，４－エポキシシクロヘキシル）エチルトリメトキシシラン等のエポキシ基含有シランカップリング剤；３－アミノプロピルトリメトキシシラン、Ｎ－２－（アミノエチル）－３－アミノプロピルメチルジメトキシシラン、３－トリエトキシシリル－Ｎ－（１，３－ジメチルブチリデン）プロピルアミン、Ｎ－フェニル－γ－アミノプロピルトリメトキシシラン等のアミノ基含有シランカップリング剤；３－アクリロキシプロピルトリメトキシシラン、３－メタクリロキシプロピルトリエトキシシラン等の（メタ）アクリル基含有シランカップリング剤；３－イソシアネートプロピルトリエトキシシラン等のイソシアネート基含有シランカップリング剤等が挙げられる。 Silane coupling agents include, for example, epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.
　シランカップリング剤の含有量は、モノマー成分の全質量に対して、１質量％以下であることが好ましく、０．０１～１質量％の範囲内であることがより好ましく、０．０２～０．６質量％の範囲内であることが更に好ましい。 The content of the silane coupling agent is preferably 1% by mass or less, more preferably in the range of 0.01 to 1% by mass, and even more preferably in the range of 0.02 to 0.6% by mass, based on the total mass of the monomer components.
　架橋剤としては、例えば、イソシアネート系架橋剤、エポキシ系架橋剤、シリコーン系架橋剤、オキサゾリン系架橋剤、アジリジン系架橋剤、シラン系架橋剤、アルキルエーテル化メラミン系架橋剤、金属キレート系架橋剤、過酸化物等の架橋剤が挙げられる。中でも、イソシアネート系架橋剤であることが好ましい。
　これらは、一種単独で用いても、二種以上併用してもよい。 Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxides, etc. Among these, isocyanate-based crosslinking agents are preferred.
These may be used alone or in combination of two or more.
　イソシアネート系架橋剤は、イソシアネート基（イソシアネート基をブロック剤又は多量体化等により一時的に保護したイソシアネート再生型官能基を含む）を１分子中に２個以上有する化合物である。イソシアネート系架橋剤としては、トリレンジイソシアネート、キシレンジイソシアネート等の芳香族イソシアネート；イソホロンジイソシアネート等の脂環族イソシアネート；ヘキサメチレンジイソシアネート等の脂肪族イソシアネート等が挙げられる。 An isocyanate crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or by polymerization, etc.) in one molecule. Examples of isocyanate crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.
　架橋剤の含有量は、モノマー成分の全質量に対して、５質量％以下であることが好ましく、０．０１～５質量％の範囲内であることがより好ましく、０．０１～４質量％の範囲内であることが更に好ましく、０．０２～３質量％の範囲内であることが特に好ましい。 The content of the crosslinking agent is preferably 5% by mass or less, more preferably in the range of 0.01 to 5% by mass, even more preferably in the range of 0.01 to 4% by mass, and particularly preferably in the range of 0.02 to 3% by mass, based on the total mass of the monomer components.
　紫外線硬化型アクリル系粘着剤は、上記成分の他に、用途に応じて、他の添加剤を適宜含有してもよい。このような添加剤としては、例えば、粘着付与剤（例えば、ロジン誘導体樹脂、ポリテルペン樹脂、石油樹脂、油溶性フェノール樹脂等からなる常温で固体、半固体、又は液状のもの）；中空ガラスバルーン等の充填剤；可塑剤；老化防止剤；酸化防止剤等が挙げられる。 In addition to the above components, the UV-curable acrylic adhesive may contain other additives as appropriate depending on the application. Examples of such additives include tackifiers (e.g., rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc. that are solid, semi-solid, or liquid at room temperature); fillers such as hollow glass balloons; plasticizers; antioxidants; antioxidants, etc.
　紫外線硬化型アクリル系粘着剤は、塗布作業に適した粘度に調整することが好ましい。粘度は、例えば、増粘性添加剤等の各種ポリマー、多官能性モノマー等を添加すること、また、紫外線硬化型アクリル系粘着剤中のモノマー成分を部分重合させることにより調整できる。なお、当該部分重合は、増粘性添加剤等の各種ポリマー、多官能性モノマー等を添加する前に行ってもよく、その後に行ってもよい。 It is preferable to adjust the viscosity of the UV-curable acrylic adhesive to a level suitable for application. The viscosity can be adjusted, for example, by adding various polymers such as thickening additives, polyfunctional monomers, etc., or by partially polymerizing the monomer components in the UV-curable acrylic adhesive. The partial polymerization may be carried out before or after adding various polymers such as thickening additives, polyfunctional monomers, etc.
　紫外線硬化型アクリル系粘着剤の粘度は、添加剤の含有量等によって変わる。そのため、紫外線硬化型アクリル系粘着剤中のモノマー成分を部分重合させる場合の重合率は、一意に決めることはできない。ただし、目安として、重合率は、２０％以下であることが好ましく、３～２０％の範囲内であることがより好ましく、５～１５％の範囲内であることが更に好ましい。
　なお、重合率が２０％以下であることにより、塗布作業に適した粘度に調整できる。 The viscosity of the ultraviolet-curable acrylic adhesive varies depending on the content of additives, etc. Therefore, the polymerization rate when the monomer components in the ultraviolet-curable acrylic adhesive are partially polymerized cannot be uniquely determined. However, as a guideline, the polymerization rate is preferably 20% or less, more preferably within the range of 3 to 20%, and even more preferably within the range of 5 to 15%.
In addition, by controlling the polymerization rate to 20% or less, the viscosity can be adjusted to a level suitable for application work.
　（３．５）粘着層の作製方法
　粘着層は、紫外線硬化型アクリル系粘着剤を、隣接する層上に塗布し、紫外線を照射して、紫外線硬化（紫外線重合）することにより作製できる。
　また、基材上に紫外線硬化型アクリル系粘着剤を塗布し、紫外線を照射して、紫外線硬化（紫外線重合）することによりフィルム状の粘着層を作製できる。 (3.5) Method for Producing Adhesive Layer The adhesive layer can be produced by applying an ultraviolet-curable acrylic adhesive onto an adjacent layer, and irradiating it with ultraviolet light to cause ultraviolet curing (ultraviolet polymerization).
Alternatively, an ultraviolet-curable acrylic adhesive may be applied onto a substrate, and then ultraviolet light may be irradiated to cause ultraviolet curing (ultraviolet polymerization) to produce a film-like adhesive layer.
　基材は、特に制限されず、例えば、離型フィルム、透明樹脂フィルム等が挙げられる。 The substrate is not particularly limited, and examples include release films, transparent resin films, etc.
　離型フィルムとしては、例えば、ポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、ポリエステルフィルム等の離型樹脂フィルム、紙、布、不織布等の多孔質材料、ネット、発泡シート、金属箔、又はこれらのラミネート体等の薄葉体が挙げられる。中でも、表面平滑性に優れる観点から、樹脂フィルムであることが好ましい。 Examples of release films include release resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; and thin materials such as nets, foam sheets, metal foils, and laminates of these. Among these, resin films are preferred from the viewpoint of excellent surface smoothness.
　離型樹脂フィルムとしては、例えば、ポリエチレンフィルム、ポリプロピレンフィルム、ポリブテンフィルム、ポリブタジエンフィルム、ポリメチルペンテンフィルム、ポリ塩化ビニルフィルム、塩化ビニル共重合体フィルム、ポリエチレンテレフタレートフィルム、ポリブチレンテレフタレートフィルム、ポリウレタンフィルム、エチレン－酢酸ビニル共重合体フィルム等が挙げられる。 Examples of release resin films include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.
　離型フィルムの厚さは、５～２００μｍの範囲内であることが好ましく、５～１００μｍの範囲内であることが好ましい。 The thickness of the release film is preferably within the range of 5 to 200 μm, and more preferably within the range of 5 to 100 μm.
　離型フィルムには、必要に応じて、シリコーン系、フッ素系、長鎖アルキル系又は脂肪酸アミド系の離型剤による離型処理をすることが好ましい。また、シリカ粉等により、防汚処理をすることが好ましい。その他、塗布型、練り込み型、蒸着型等の帯電防止処理をしてもよい。特に、シリコーン系、フッ素系又は長鎖アルキル系の離型剤による離型処理をすることにより、フィルム状の粘着層を剥離しやすくする。 If necessary, the release film is preferably subjected to a release treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent. It is also preferable to perform an anti-soiling treatment using silica powder or the like. In addition, anti-static treatments such as coating, kneading or deposition may be performed. In particular, release treatment using a silicone-based, fluorine-based or long-chain alkyl-based release agent makes it easier to peel off the film-like adhesive layer.
　透明樹脂フィルムは、特に制限されないが、透明性を有し、かつ一層のフィルムで構成されていることが好ましい。
　透明樹脂フィルムとしては、例えば、ポリエチレンテレフタレート、ポリエチレンナフタレート等のポリエステル系樹脂、アセテート系樹脂、ポリエーテルスルホン系樹脂、ポリカーボネート系樹脂、ポリアミド系樹脂、ポリイミド系樹脂、ポリオレフィン系樹脂、（メタ）アクリル系樹脂、ポリ塩化ビニル系樹脂、ポリ塩化ビニリデン系樹脂、ポリスチレン系樹脂、ポリビニルアルコール系樹脂、ポリアリレート系樹脂、ポリフェニレンサルファイド系樹脂等が挙げられる。
　中でも、ポリエステル系樹脂、ポリイミド系樹脂又はポリエーテルスルホン系樹脂であることが好ましい。 The transparent resin film is not particularly limited, but is preferably transparent and composed of a single layer film.
Examples of transparent resin films include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins.
Among these, polyester resins, polyimide resins, and polyethersulfone resins are preferred.
　透明樹脂フィルムの厚さは、２～２００μｍの範囲内であることが好ましく、２０～１８８μｍの範囲内であることがより好ましい。 The thickness of the transparent resin film is preferably within the range of 2 to 200 μm, and more preferably within the range of 20 to 188 μm.
　紫外線硬化型アクリル系粘着剤を塗布する方法は、特に制限されず、従来公知の方法を用いることができる。塗布方法としては、ロールコート法、キスロールコート法、グラビアコート法、リバースコート法、ロールブラッシュ法、スプレーコート法、ディップロールコート法、バーコート法、ナイフコート法、エアーナイフコート法、カーテンコート法、リップコート法、ダイコーター法等が挙げられる。 The method for applying the UV-curable acrylic adhesive is not particularly limited, and any conventionally known method can be used. Examples of application methods 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 coater methods.
　紫外線硬化型アクリル系粘着剤に照射する紫外線の照度は、５～２００ｍＷ／ｃｍ２の範囲内であることが好ましい。紫外線の照度が５ｍＷ／ｃｍ２以上であることにより、重合反応時間を短くでき、生産性に優れる。また、紫外線の照度が２００ｍＷ／ｃｍ２以下であることにより、光重合開始剤が急激に消費されるのを抑制できる。その結果、重合が十分に進行し、高分子量の重合体（（メタ）アクリル系ポリマー）が得られる。これにより、特に高温時における保持力に優れた粘着層とすることができる。
　紫外線の積算光量は、１００～５０００ｍＪ／ｃｍ２の範囲内であることが好ましい。 The illuminance of the ultraviolet light irradiated to the ultraviolet-curable acrylic adhesive is preferably within the range of 5 to 200 mW/ cm2 . By setting the illuminance of the ultraviolet light to 5 mW/ cm2 or more, the polymerization reaction time can be shortened, resulting in excellent productivity. Furthermore, by setting the illuminance of the ultraviolet light to 200 mW/ cm2 or less, the photopolymerization initiator can be prevented from being rapidly consumed. As a result, the polymerization proceeds sufficiently, and a high molecular weight polymer ((meth)acrylic polymer) can be obtained. This allows the adhesive layer to have excellent holding power, especially at high temperatures.
The integrated amount of ultraviolet light is preferably within the range of 100 to 5000 mJ/ cm2 .
　本発明に用いられる紫外線ランプは、特に制限されないが、ＬＥＤランプであることが好ましい。ＬＥＤランプは、他の紫外線ランプに比べて放出熱が低いランプであるため、紫外線硬化型アクリル系粘着剤の紫外線硬化中における温度の上昇を抑制できる。これにより、高分子量の重合体が得られ、十分な凝集力を有する粘着層が得られ、粘着シートとした場合の高温時における保持力を高めることができる。
　紫外線ランプは、複数の紫外線ランプを組み合わせて用いてもよい。また、照射方法としては、紫外線を間欠的に照射し、紫外線を照射する明期と紫外線を照射しない暗期とを設けてもよい。 The ultraviolet lamp used in the present invention is not particularly limited, but is preferably an LED lamp. The LED lamp emits less heat than other ultraviolet lamps, so that the temperature rise during the ultraviolet curing of the ultraviolet curing acrylic adhesive can be suppressed. This allows a polymer with a high molecular weight to be obtained, and an adhesive layer with sufficient cohesive strength can be obtained, thereby increasing the holding power at high temperatures when the adhesive sheet is made.
The ultraviolet lamp may be a combination of a plurality of ultraviolet lamps. As for the irradiation method, ultraviolet light may be intermittently irradiated, and a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated may be provided.
　紫外線硬化型アクリル系粘着剤中のモノマー成分の最終的な重合率は、９０％以上であることが好ましく、９５％以上であることがより好ましく、９８％以上であることが更に好ましい。 The final polymerization rate of the monomer components in the UV-curable acrylic adhesive is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.
　紫外線硬化型アクリル系粘着剤に照射する紫外線のピーク波長は、２００～５００ｎｍの範囲内であることが好ましく、３００～４５０ｎｍの範囲内であることがより好ましい。紫外線のピーク波長が５００ｎｍ以下であることにより、光重合開始剤が分解し、重合反応が開始する。また、紫外線のピーク波長が２００ｎｍ以上であることにより、ポリマー鎖の切断を抑制でき、十分な接着性が得られる。 The peak wavelength of the ultraviolet light irradiated onto the ultraviolet-curing acrylic adhesive is preferably within the range of 200 to 500 nm, and more preferably within the range of 300 to 450 nm. When the peak wavelength of the ultraviolet light is 500 nm or less, the photopolymerization initiator decomposes and the polymerization reaction begins. Furthermore, when the peak wavelength of the ultraviolet light is 200 nm or more, the scission of the polymer chain can be suppressed, and sufficient adhesion can be obtained.
　重合反応は空気中の酸素によって阻害されやすいため、酸素を遮断することが好ましい。酸素を遮断する方法としては、紫外線硬化型アクリル系粘着剤の塗布層上に離型フィルム等を作製したり、重合反応を窒素雰囲気下で行ったりする方法が挙げられる。離型フィルムとしては、前出の離型フィルムが挙げられる。 Since the polymerization reaction is easily inhibited by oxygen in the air, it is preferable to block oxygen. Methods for blocking oxygen include creating a release film on the coating layer of the UV-curable acrylic adhesive, and carrying out the polymerization reaction in a nitrogen atmosphere. Examples of release films include the release films mentioned above.
　（３．６）粘着層の物性
　粘着層の２５℃における貯蔵弾性率は、耐衝撃性及び屈曲後のコントラストの両立の観点から、０．５～１０．０ＭＰａの範囲内であることが好ましく、１．２～８．０ＭＰａの範囲内であることがより好ましい。 (3.6) Physical Properties of Adhesive Layer From the viewpoint of achieving both impact resistance and contrast after bending, the storage modulus of the adhesive layer at 25° C. is preferably within the range of 0.5 to 10.0 MPa, and more preferably within the range of 1.2 to 8.0 MPa.
　特に、粘着層Ｄの２５℃における貯蔵弾性率は、０．５～８ＭＰａの範囲内であることが好ましい。 In particular, it is preferable that the storage modulus of adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
　粘着層の２５℃における貯蔵弾性率は、材料（モノマー成分、紫外線吸収剤、光重合開始剤等）の種類、含有量、紫外線の照射条件等を適宜選択することにより、調整できる。 The storage modulus of the adhesive layer at 25°C can be adjusted by appropriately selecting the type and content of materials (monomer components, UV absorbers, photopolymerization initiators, etc.), UV irradiation conditions, etc.
　粘着層の、２５℃における貯蔵弾性率は、粘弾性測定装置「ＡＲＥＳ－Ｇ２」（ティー・エイ・インスツルメント・ジャパン株式会社製）を用い、下記の試験条件にて測定できる。
　試験条件（動的粘弾性試験）
　試験機：粘弾性測定装置「ＡＲＥＳ－Ｇ２」（ティー・エイ・インスツルメント・ジャパン株式会社製）
　変形方法：回転式
　温度範囲：－５０～１００℃
　周波数：１Ｈｚ
　変位：歪０．０５％
　サンプルサイズ（形態など）：φ８ｍｍ　厚さ約１ｍｍ
　チャック間距離：荷重１０ｇになるように自動可変（サンプル厚さとほぼ同等）。 The storage modulus of the adhesive layer at 25° C. can be measured using a viscoelasticity measuring device "ARES-G2" (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
Test conditions (dynamic viscoelasticity test)
Testing machine: Viscoelasticity measuring device "ARES-G2" (manufactured by TA Instruments Japan, Inc.)
Deformation method: Rotation Temperature range: -50 to 100°C
Frequency: 1Hz
Displacement: Strain 0.05%
Sample size (shape, etc.): φ8mm, thickness approx. 1mm
Distance between chucks: Automatically variable so that the load becomes 10 g (approximately equal to the sample thickness).
　粘着層の厚さは、最終的に得られる積層体をより薄くする観点から、２～６０μｍの範囲内であることが好ましく、２～２０μｍの範囲内であることがより好ましく、５～１５μｍの範囲内であることが更に好ましい。 The thickness of the adhesive layer is preferably within the range of 2 to 60 μm, more preferably within the range of 2 to 20 μm, and even more preferably within the range of 5 to 15 μm, from the viewpoint of making the final laminate thinner.
　粘着層で用いられる樹脂材料（例えば、（メタ）アクリル系ポリマー）の重量平均分子量（Ｍｗ）は、貯蔵弾性率を制御する観点から、１０万～５００万の範囲内であることが好ましく、２０万～１００万の範囲内であることがより好ましい。 The weight average molecular weight (Mw) of the resin material (e.g., (meth)acrylic polymer) used in the adhesive layer is preferably within the range of 100,000 to 5,000,000, and more preferably within the range of 200,000 to 1,000,000, from the viewpoint of controlling the storage modulus.
　粘着層で用いられる樹脂材料の重量平均分子量（Ｍｗ）は、光学フィルムで用いられる樹脂材料の重量平均分子量（Ｍｗ）よりも小さいことが好ましい。これにより、本発明の効果をより効率よく得られる。 The weight average molecular weight (Mw) of the resin material used in the adhesive layer is preferably smaller than the weight average molecular weight (Mw) of the resin material used in the optical film. This allows the effects of the present invention to be obtained more efficiently.
　なお、樹脂材料の重量平均分子量（Ｍｗ）は、ゲル浸透クロマトグラフィー「ＨＬＣ８２２０ＧＰＣ」（東ソー株式会社製）、及びカラム「ＴＳＫ－ＧＥＬ　Ｇ６０００」、「ＨＸＬ－Ｇ５０００」、「ＨＸＬ－Ｇ５０００」、「ＨＸＬ－Ｇ４０００」、「ＨＸＬ－Ｇ３０００ＨＸＬ」（以上、東ソー株式会社製、直列）を用いて測定できる。
　試料２０ｍｇ±０．５ｍｇを、テトラヒドロフラン１０ｍＬに溶解し、０．４５ｍｍのフィルターで濾過する。そして、この溶液をカラム（温度４０℃）に１００ｍＬ注入し、ＲＩ検出器、温度４０℃で測定し、スチレン換算した値とする。 The weight average molecular weight (Mw) of the resin material can be measured using a gel permeation chromatograph "HLC8220GPC" (manufactured by Tosoh Corporation) and columns "TSK-GEL G6000", "HXL-G5000", "HXL-G5000", "HXL-G4000", and "HXL-G3000HXL" (all manufactured by Tosoh Corporation, in series).
20 mg±0.5 mg of a sample is dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution is then injected into a column (temperature 40° C.) and measured with an RI detector at a temperature of 40° C., and the value is expressed in terms of styrene.
　粘着層のガラス転移温度（Ｔｇ）は、低温環境下での耐衝撃性及び屈曲後のコントラストの両立の観点から、０℃以下であることが好ましく、－１０℃以下であることがより好ましく、－２０℃以下であることが更に好ましい。 The glass transition temperature (Tg) of the adhesive layer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower, from the viewpoint of achieving both impact resistance in a low-temperature environment and contrast after bending.
　ガラス転移温度（Ｔｇ）は、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｓｃａｎｎｉｎｇ　Ｃｏｌｏｒｉｍｅｔｒｙ：示差走査熱量装置）を用いて、ＪＩＳ　Ｋ　７１２１（２０１２）に準拠して測定できる。 The glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.
　３．積層体の製造方法
　本発明の積層体の製造方法は、特に制限されず、ガラス層（薄膜ガラス）、光学フィルム、必要に応じて粘着層（紫外線硬化型アクリル系粘着剤）を順次配置していく方法が挙げられる。 3. Manufacturing Method of Laminate The manufacturing method of the laminate of the present invention is not particularly limited, and examples thereof include a method of sequentially arranging a glass layer (thin film glass), an optical film, and, if necessary, an adhesive layer (ultraviolet-curable acrylic adhesive).
　４．積層体の物性
　本発明の積層体において、光学フィルムＡ及び光学フィルムＢの、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、ＴＡ及びＴＢが、上記式（１）を満たし、かつＴＡ及びＴＢが、共に３９～８９％の範囲内である。
　また、粘着層Ｃの３８０～７８０ｎｍの波長領域における平均光透過率をＴＣとしたとき、ＴＢ及びＴＣが上記式（２）を満たすことが好ましい。 In the laminate of the present invention, when the average light transmittances of the optical film A and the optical film B in the wavelength region of 380 to 780 nm are T A and T B , respectively, T A and T B satisfy the above formula (1) and both T A and T B are within the range of 39 to 89%.
In addition, when the average light transmittance of the adhesive layer C in the wavelength region of 380 to 780 nm is defined as T C , it is preferable that T B and T C satisfy the above formula (2).
　さらに、粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内であることが好ましい。 Furthermore, it is preferable that the storage modulus of the adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
　本発明の積層体の厚さは、耐衝撃性及び屈曲後のコントラストを両立する観点から、３０～１１０μｍの範囲内であることが好ましく、５５～９５μｍの範囲内であることがより好ましい。 The thickness of the laminate of the present invention is preferably within the range of 30 to 110 μm, and more preferably within the range of 55 to 95 μm, from the viewpoint of achieving both impact resistance and contrast after bending.
　５．表示装置
　本発明の表示装置は、本発明の積層体を具備することを特徴とする。
　また、光学フィルムＡが、光学フィルムＢよりも当該表示装置の視認側に配置されることが好ましい。 5. Display Device The display device of the present invention is characterized by comprising the laminate of the present invention.
It is also preferable that the optical film A is disposed closer to the viewing side of the display device than the optical film B.
　本発明の表示装置は、本発明の積層体（カバーユニット）を、下記の表示装置（表示ユニット）の表面に取り付けることにより得られる。取り付け方法は、特に制限されないが、粘着剤を用いて貼り合わせることが好ましい。粘着剤は、特に制限されないが、耐衝撃性及び屈曲後のコントラストの観点から、上記粘着層を有する積層体をカバーユニットとして用いることが好ましい。 The display device of the present invention can be obtained by attaching the laminate (cover unit) of the present invention to the surface of the display device (display unit) described below. The attachment method is not particularly limited, but it is preferable to use an adhesive to attach them together. The adhesive is not particularly limited, but from the viewpoints of impact resistance and contrast after bending, it is preferable to use a laminate having the above-mentioned adhesive layer as the cover unit.
　また、本発明の表示装置は、本発明の積層体（カバーユニット）と、下記の表示装置（表示ユニット）との間に偏光板を有していてもよい。ただし、本発明の積層体が外光反射を抑制できる、すなわち、本発明の積層体が偏光板としての機能の一部を有しているため、必ずしも、偏光板を有していなくてもよい。 The display device of the present invention may also have a polarizing plate between the laminate of the present invention (cover unit) and the display device (display unit) described below. However, since the laminate of the present invention can suppress external light reflection, that is, since the laminate of the present invention has some of the functions of a polarizing plate, it does not necessarily have to have a polarizing plate.
　本発明において、「表示装置」とは、表示機構を有する装置のことをいい、発光源として発光素子又は発光装置を有する。
　表示装置としては、液晶表示装置、有機エレクトロルミネッセンス（ＥＬ）表示装置、無機エレクトロルミネッセンス（ＥＬ）表示装置、タッチパネル表示装置、電子放出表示装置（電場放出表示装置（ＦＥＤ等）、表面電界放出表示装置（ＳＥＤ））、電子ペーパー（電子インクや電気泳動素子を用いた表示装置）、プラズマ表示装置、投射型表示装置（グレーティングライトバルブ（ＧＬＶ）表示装置、デジタルマイクロミラーデバイス（ＤＭＤ）を有する表示装置等）、圧電セラミックディスプレイ等が挙げられる。
　なお、液晶表示装置としては、透過型液晶表示装置、半透過型液晶表示装置、反射型液晶表示装置、直視型液晶表示装置、投写型液晶表示装置等が挙げられる。 In the present invention, the term "display device" refers to a device having a display mechanism, and has a light-emitting element or a light-emitting device as a light source.
Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (such as a field emission display device (FED) and a surface field emission display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection type display device (such as a grating light valve (GLV) display device and a display device having a digital micromirror device (DMD)), a piezoelectric ceramic display, and the like.
Examples of the liquid crystal display device include a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device.
　これらの表示装置は、二次元画像を表示する表示装置であってもよいし、三次元画像を表示する立体表示装置であってもよい。
　中でも、有機ＥＬ表示装置又はタッチパネル表示装置であることが好ましく、有機ＥＬ表示装置であることがより好ましい。 These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images.
Among these, an organic EL display device or a touch panel display device is preferable, and an organic EL display device is more preferable.
　本発明の表示装置は、本発明の積層体（カバーユニット）を具備することにより、使用時における外光反射を抑制でき、折り曲げを行った後においても良好なコントラストが得られる。また、ペン入力にも対応した良好な耐衝撃性が得られる。 The display device of the present invention is equipped with the laminate (cover unit) of the present invention, which makes it possible to suppress external light reflection during use and to obtain good contrast even after bending. It also provides good impact resistance that is compatible with pen input.
　図５及び図６に、本発明の表示装置の一例である有機ＥＬディスプレイへの適用例を示す。
　図５に示す表示装置１００は、有機ＥＬ層１０１に、粘着層Ｃ４を介して、積層体２０が配置されている。なお、必要に応じて、図６に示すように、粘着層Ｄ等の他の層が配置されていてもよい。 5 and 6 show an example of application of the present invention to an organic EL display, which is an example of a display device.
In the display device 100 shown in Fig. 5, a laminate 20 is disposed on an organic EL layer 101 via an adhesive layer C4. If necessary, other layers such as an adhesive layer D may be disposed as shown in Fig. 6.
　通常、有機ＥＬディスプレイは、電極／電子輸送層／発光層／ホール輸送層／透明電極からなる有機ＥＬ層、及び画質を向上させるための位相差板（λ／４板）具備する偏光板から構成される。ただし、本発明の積層体は、偏光板としての機能の一部を有しているため、必ずしも、偏光板を有していなくてもよい。 Normally, an organic EL display is composed of an organic EL layer consisting of an electrode/electron transport layer/light-emitting layer/hole transport layer/transparent electrode, and a polarizing plate equipped with a retardation plate (lambda/4 plate) to improve image quality. However, since the laminate of the present invention has some of the functions of a polarizing plate, it does not necessarily have to have a polarizing plate.
　また、本発明の表示装置は、折り畳み型ディスプレイとしてもよい。折り畳み型ディスプレイは、連続した１枚のディスプレイを、携帯時には二つ折りにすることでサイズを半減させ、携帯性を向上させる構造であることが好ましい。折り畳み型ディスプレイは、さらに、薄型、かつ軽量であることが好ましい。 The display device of the present invention may also be a foldable display. A foldable display is preferably a single continuous display that can be folded in half when carried, reducing its size by half and improving portability. It is further preferable that the foldable display is thin and lightweight.
　本発明の積層体は、外光反射を抑制することに加え、耐衝撃性が良好であり、繰り返し畳んでも折り跡が付きにくい。また、繰り返し折り畳んだ後でもコントラストを維持できる。そのため、折り畳み型ディスプレイにおいて、繰り返し折り畳んだ後の視認性、具体的には、折り畳み部分における画像の乱れの抑制に優れる。 The laminate of the present invention not only suppresses external light reflection, but also has good impact resistance and is less likely to leave creases even when folded repeatedly. It also maintains contrast even after repeated folding. Therefore, in a foldable display, it is excellent in visibility after repeated folding, specifically in suppressing image distortion at the folded parts.
　以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。なお、実施例において「部」又は「％」の表示を用いるが、特に断りがない限り「質量部」又は「質量％」を表す。
　また、下記実施例において、特記しない限り操作は室温（２５℃）で行われた。 The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the examples, the terms "parts" and "%" are used, but they represent "parts by mass" or "% by mass" unless otherwise specified.
In the following examples, operations were carried out at room temperature (25° C.) unless otherwise specified.
　１．測定方法
　光学フィルム及び粘着層Ｃの可視光領域における平均光透過率については、下記方法で測定した。
　また、粘着層Ｄの貯蔵弾性率については、下記方法で測定した。 1. Measurement Method The average light transmittance in the visible light region of the optical film and the adhesive layer C was measured by the following method.
The storage modulus of the adhesive layer D was measured by the following method.
　（平均光透過率）
　各光学フィルムを、気温２３℃、相対湿度５５ＲＨの空調室で２４時間調湿する。そして、ＪＩＳ　Ｋ－７３７５：２００８に準拠して、紫外可視分光光度計（例えば、「ＵＶ－２４５０」（株式会社島津製作所製））を用いて、３８０～７８０ｎｍの波長領域における各波長の全光線透過率を測定し、その算術平均値を求めた。 (Average Light Transmittance)
Each optical film was conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, a UV-visible spectrophotometer (for example, “UV-2450” (manufactured by Shimadzu Corporation)) was used to measure the total light transmittance of each wavelength in the wavelength range of 380 to 780 nm, and the arithmetic average value was calculated.
　（粘着層Ｄの貯蔵弾性率）
　粘着層の２５℃における貯蔵弾性率は、粘弾性測定装置「ＡＲＥＳ－Ｇ２」（ティー・エイ・インスツルメント・ジャパン株式会社製）を用い、下記の試験条件にて測定した。
　試験条件（動的粘弾性試験）
　試験機：粘弾性測定装置「ＡＲＥＳ－Ｇ２」（ティー・エイ・インスツルメント・ジャパン株式会社製）
　変形方法：回転式
　温度範囲：－５０～１００℃
　周波数：１Ｈｚ
　変位：歪０．０５％
　サンプルサイズ（形態など）：φ８ｍｍ　厚さ約１ｍｍ
　チャック間距離：荷重１０ｇになるように自動可変（サンプル厚さとほぼ同等）。 (Storage Modulus of Adhesive Layer D)
The storage modulus of the adhesive layer at 25° C. was measured using a viscoelasticity measuring device “ARES-G2” (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
Test conditions (dynamic viscoelasticity test)
Testing machine: Viscoelasticity measuring device "ARES-G2" (manufactured by TA Instruments Japan, Inc.)
Deformation method: Rotation Temperature range: -50 to 100°C
Frequency: 1Hz
Displacement: Strain 0.05%
Sample size (shape, etc.): φ8mm, thickness approx. 1mm
Distance between chucks: Automatically variable so that the load becomes 10 g (approximately equal to the sample thickness).
　２．積層体の作製
　（１）光学フィルムＡの作製
　（１．１）光学フィルムＡ１の作製
　（１．１．１）エステル化合物１の合成
　１，２－プロピレングリコール　　　　　　　　　　　　　　２５１ｇ
　無水フタル酸　　　　　　　　　　　　　　　　　　　　　　２７８ｇ
　アジピン酸　　　　　　　　　　　　　　　　　　　　　　　　９１ｇ
　安息香酸　　　　　　　　　　　　　　　　　　　　　　　　６１０ｇ
　テトライソプロピルチタネート（エステル化触媒）　　　０．１９１ｇ
　上記成分を、温度計、撹拌器、緩急冷却管を備えた２Ｌの四つ口フラスコに仕込み、窒素気流中２３０℃になるまで、撹拌しながら徐々に昇温した。１５時間脱水縮合反応させ、反応終了後２００℃で未反応の１，２－プロピレングリコールを減圧留去することにより、エステル化合物１を得た。当該エステル化合物１の酸価は、０．１０、数平均分子量は、４５０であった。 2. Preparation of Laminate (1) Preparation of Optical Film A (1.1) Preparation of Optical Film A1 (1.1.1) Synthesis of Ester Compound 1 1,2-propylene glycol 251 g
Phthalic anhydride 278g
Adipic acid 91g
Benzoic acid 610g
Tetraisopropyl titanate (esterification catalyst) 0.191 g
The above components were charged into a 2 L four-neck flask equipped with a thermometer, a stirrer, and a slow and fast cooling tube, and the temperature was gradually raised with stirring in a nitrogen stream up to 230° C. A dehydration condensation reaction was carried out for 15 hours, and after completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200° C. to obtain ester compound 1. The acid value of the ester compound 1 was 0.10, and the number average molecular weight was 450.
　（１．１．２）二酸化珪素希釈液の調製
　「アエロジル（登録商標）Ｒ８１２」（日本アエロジル（株）製、一次粒子の平均径：７ｎｍ）
　　　　　　　　　　　　　　　　　　　　　　　　　　　　１０質量部
　エタノール　　　　　　　　　　　　　　　　　　　　　　９０質量部
　上記成分をディゾルバーで３０分間撹拌混合した後、マントンゴーリンで分散を行い、二酸化珪素分散液を調製した。
　メチレンクロライド　　　　　　　　　　　　　　　　　　８８質量部
　二酸化珪素分散液に、上記成分を撹拌しながら投入し、ディゾルバーで３０分間撹拌混合し、二酸化珪素分散希釈液を調製した。微粒子分散希釈液濾過器「ポリプロピレンワインドカートリッジフィルターＴＣＷ－ＰＰＳ－１Ｎ」（アドバンテック東洋株式会社製）で濾過した。 (1.1.2) Preparation of silicon dioxide dilute solution "Aerosil (registered trademark) R812" (manufactured by Nippon Aerosil Co., Ltd., average diameter of primary particles: 7 nm)
10 parts by weight Ethanol 90 parts by weight The above components were mixed by stirring for 30 minutes using a dissolver, and then dispersed using a Manton-Gaulin to prepare a silicon dioxide dispersion.
Methylene chloride 88 parts by mass The above components were added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a diluted silicon dioxide dispersion. The diluted fine particle dispersion was filtered with a polypropylene wound cartridge filter TCW-PPS-1N (manufactured by Advantec Toyo Co., Ltd.).
　（１．１．３）ドープの調製
　セルローストリアセテートＡ１
　（リンター綿から合成されたセルローストリアセテート、アセチル基置換度２．８８、Ｍｎ＝１４００００）
　　　　　　　　　　　　　　　　　　　　　　　　　　　　９０質量部
　上記エステル化合物１　　　　　　　　　　　　　　　　　１０質量部
　「チヌビン９２８」（チバ・ジャパン（株）製）　　　　２．５質量部
　着色剤Ｐ１　　　　　　　　　　　　　　　　　　　　０．０８質量部
　上記二酸化珪素分散希釈液　　　　　　　　　　　　　　　　４質量部
　メチレンクロライド　　　　　　　　　　　　　　　　　４３２質量部
　エタノール　　　　　　　　　　　　　　　　　　　　　　３８質量部
　上記成分を密閉容器に投入し、加熱し、撹拌しながら、完全に溶解し、安積濾紙（株）製の安積濾紙Ｎｏ．２４を使用して濾過し、ドープ液を調製した。 (1.1.3) Preparation of dope Cellulose triacetate A1
(Cellulose triacetate synthesized from linter cotton, acetyl substitution degree 2.88, Mn = 140,000)
The above components were charged into a sealed container, heated and stirred to completely dissolve, and filtered using Azumi Filter Paper No. 24 manufactured by Azumi Filter Paper Co., Ltd. to prepare a dope solution.
　（１．１．４）光学フィルムＡ１の形成
　次に、ベルト流延装置を用い、ステンレスバンド支持体に均一に流延した。ステンレスバンド支持体で、残留溶剤量が１００％になるまで溶剤を蒸発させ、ステンレスバンド支持体上から剥離した。 (1.1.4) Formation of Optical Film A1 Next, the optical film A1 was uniformly cast onto a stainless steel band support using a belt casting device. The solvent was evaporated on the stainless steel band support until the residual solvent amount was 100%, and the stainless steel band support was peeled off.
　セルロースエステルフィルムのウェブを３５℃で溶剤を蒸発させ、１．７ｍ幅にスリットした。次いで、テンターでＴＤ方向（フィルムの幅手方向）に１．３倍（３０％の延伸倍率）に延伸しながら、１６０℃の乾燥温度（「熱処理温度」、「延伸温度」ともいう。）で乾燥させた。このとき、テンターで延伸を始めたときの残留溶剤量（「残溶」ともいう。）は２０％であった。その後、１２０℃の乾燥装置内を多数のロールで搬送させながら１５分間乾燥させた。そして、２．２ｍ幅にスリットし、フィルム両端に幅１５ｍｍ、高さ１０μｍのナーリング加工を施し、巻芯に巻き取り、光学フィルムＡ１を得た。光学フィルムの残留溶剤量は０．２％であり、厚さは４０μｍ、巻数は６０００ｍであった。 The cellulose ester film web was slit to a width of 1.7 m after evaporating the solvent at 35°C. It was then stretched in the TD direction (width direction of the film) by 1.3 times (stretching ratio of 30%) with a tenter while drying at a drying temperature of 160°C (also called the "heat treatment temperature" or "stretching temperature"). At this time, the amount of residual solvent (also called "residual solution") when stretching with the tenter started was 20%. It was then dried for 15 minutes while being transported by multiple rolls in a drying device at 120°C. It was then slit to a width of 2.2 m, knurled at both ends of the film to a width of 15 mm and a height of 10 μm, and wound around a core to obtain optical film A1. The amount of residual solvent in the optical film was 0.2%, the thickness was 40 μm, and the number of windings was 6000 m.
　（１．２）光学フィルムＡ２～Ａ１１の作製
　光学フィルムＡ１の作製において、樹脂の種類、ゴム粒子の種類及び含有量、着色剤の種類及び含有量、並びに光学フィルムの厚さを、表Ｉ～表IVに記載のとおりに変更した以外は同様の方法で、光学フィルムＡ２～Ａ５及びＡ７～Ａ１１を作製した。
　また、光学フィルムＢ１の作製において、着色剤の含有量を表Ｉ～表IVに記載のとおりに変更した以外は同様の方法で、光学フィルムＡ６を作製した。 (1.2) Preparation of Optical Films A2 to A11 Optical films A2 to A5 and A7 to A11 were prepared in the same manner as in preparation of optical film A1, except that the type of resin, the type and content of rubber particles, the type and content of colorant, and the thickness of the optical film were changed as shown in Tables I to IV.
Further, an optical film A6 was prepared in the same manner as in the preparation of the optical film B1, except that the content of the colorant was changed as shown in Tables I to IV.
　（２）光学フィルムＢの作製
　（２．１）光学フィルムＢ１の作製
　（２．１．１）熱可塑性（メタ）アクリル系樹脂の調製
　熱可塑性（メタ）アクリル系樹脂として、ＭＭＡ（メタクリル酸メチル）／ＰＭＩ（フェニルマレイミド）／ＭＡ（アクリル酸メチル）共重合体（８５／１０／５質量比、Ｍｗ：２００万、Ｔｇ：１２２℃）を準備した。 (2) Fabrication of Optical Film B (2.1) Fabrication of Optical Film B1 (2.1.1) Preparation of Thermoplastic (Meth)acrylic Resin As a thermoplastic (meth)acrylic resin, a MMA (methyl methacrylate)/PMI (phenylmaleimide)/MA (methyl acrylate) copolymer (mass ratio of 85/10/5, Mw: 2,000,000, Tg: 122° C.) was prepared.
　（２．１．２）ゴム粒子（グラフト共重合体）Ｒ１の作製
　以下の方法で作製したゴム粒子（グラフト共重合体）を用いた。 (2.1.2) Preparation of Rubber Particles (Graft Copolymer) R1 Rubber particles (graft copolymer) prepared by the following method were used.
　攪拌機付き８Ｌ重合装置に、下記成分を仕込んで、溶液Ｉとした。
　脱イオン水　　　　　　　　　　　　　　　　　　　　　１８０質量部
　ポリオキシエチレンラウリルエーテルリン酸　　　　０．００２質量部
　ホウ酸　　　　　　　　　　　　　　　　　　　　　０．４７３質量部
　炭酸ナトリウム　　　　　　　　　　　　　　　　　０．０４７質量部
　水酸化ナトリウム　　　　　　　　　　　　　　　　０．００８質量部 The following components were charged into an 8 L polymerization apparatus equipped with a stirrer to prepare solution I.
Deionized water 180 parts by weight Polyoxyethylene lauryl ether phosphate 0.002 parts by weight Boric acid 0.473 parts by weight Sodium carbonate 0.047 parts by weight Sodium hydroxide 0.008 parts by weight
　重合装置内を窒素ガスで充分に置換した後、内温を８０℃にし、下記成分を投入した。
　過硫酸カリウム（２質量％水溶液として投入）　　　０．０２１質量部 After thoroughly replacing the atmosphere inside the polymerization apparatus with nitrogen gas, the internal temperature was adjusted to 80° C., and the following components were added.
Potassium persulfate (added as a 2% by weight aqueous solution) 0.021 parts by weight
　次いで、下記成分からなる単量体混合物（ｃ’）を調製した。
　メタクリル酸メチル（メチルメタクリレート）　　　　８４．６質量％
　アクリル酸ｎ－ブチル（ｎ－ブチルアクリレート）　　　５．９質量％
　スチレン　　　　　　　　　　　　　　　　　　　　　　７．９質量％
　メタクリル酸アリル（アリルメタクリレート）　　　　　０．５質量％
　ｎ－オクチルメルカプタン　　　　　　　　　　　　　　１．１質量％ Next, a monomer mixture (c') consisting of the following components was prepared.
Methyl methacrylate (methyl methacrylate) 84.6% by mass
n-Butyl acrylate (n-butyl acrylate) 5.9% by mass
Styrene 7.9% by mass
Allyl methacrylate (allyl methacrylate) 0.5% by mass
n-Octyl mercaptan 1.1% by mass
　そして、下記成分からなる混合液を調製した。
　単量体混合物（ｃ’）　　　　　　　　　　　　　　　　　２１質量部
　ポリオキシエチレンラウリルエーテルリン酸　　　　　０．０７質量部
　そして、当該混合液を、上記溶液Ｉに６３分かけて連続的に添加した。さらに、６０分間重合反応を継続させることにより、最内部に含まれる硬質重合体（架橋重合体（ｃ））を得た。 Then, a mixture of the following components was prepared.
Monomer mixture (c') 21 parts by mass Polyoxyethylene lauryl ether phosphate 0.07 parts by mass Then, the mixture was continuously added to the above solution I over 63 minutes. The polymerization reaction was further continued for 60 minutes to obtain a hard polymer (crosslinked polymer (c)) contained in the innermost part.
　その後、下記成分を添加し、溶液IIとした。
　水酸化ナトリウム（２質量％水溶液として添加）　　０．０２１質量部
　過硫酸カリウム（２質量％水溶液として添加）　　　０．０６２質量部 Thereafter, the following components were added to prepare solution II.
Sodium hydroxide (added as a 2% by weight aqueous solution) 0.021 parts by weight Potassium persulfate (added as a 2% by weight aqueous solution) 0.062 parts by weight
　次いで、下記成分からなる単量体混合物（ａ’）を調製した。
　アクリル酸ｎ－ブチル（ｎ－ブチルアクリレート）　　８０．０質量％
　スチレン　　　　　　　　　　　　　　　　　　　　　１８．５質量％
　メタクリル酸アリル（アリルメタクリレート）　　　　　１．５質量％ Next, a monomer mixture (a') consisting of the following components was prepared.
n-Butyl acrylate (n-butyl acrylate) 80.0% by mass
Styrene 18.5% by mass
Allyl methacrylate (allyl methacrylate) 1.5% by mass
　そして、下記成分からなる混合液を調製した。
　単量体混合物（ａ’）　　　　　　　　　　　　　　　　　３９質量部
　ポリオキシエチレンラウリルエーテルリン酸　　　　　０．２５質量部
　そして、当該混合液を、溶液IIに１１７分かけて連続的に添加した。 Then, a mixture of the following components was prepared.
Monomer mixture (a') 39 parts by mass Polyoxyethylene lauryl ether phosphate 0.25 parts by mass Then, this mixture was continuously added to solution II over a period of 117 minutes.
　その後、下記成分を添加した。
　過硫酸カリウム（２質量％水溶液として添加）　　　０．０１２質量部
　１２０分間重合反応を継続させて、軟質層（アクリル系ゴム状重合体（ａ）からなる層）を得た。アクリル系ゴム状重合体（ａ）を構成する各モノマーの単独重合体のガラス転移温度を用いて、組成比に応じて平均して算出した軟質層のガラス転移温度（Ｔｇ）は、－３０℃であった。 The following ingredients were then added:
Potassium persulfate (added as a 2% by weight aqueous solution) 0.012 parts by weight The polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer made of acrylic rubber-like polymer (a)). The glass transition temperature (Tg) of the soft layer, calculated by averaging the glass transition temperatures of the homopolymers of the monomers constituting the acrylic rubber-like polymer (a) according to the composition ratio, was -30°C.
　その後、下記成分を添加し、溶液IIIとした。
　過硫酸カリウム（２質量％水溶液で添加）　　　　　　０．０４質量部 Thereafter, the following components were added to prepare solution III.
Potassium persulfate (added as a 2% by weight aqueous solution) 0.04 parts by weight
　そして、下記成分からなる単量体混合物（ｂ’）を調製した。
　メタクリル酸メチル（メチルメタクリレート）　　　　９７．５質量％
　アクリル酸ｎ－ブチル（ｎ－ブチルアクリレート）　　　２．５質量％ Then, a monomer mixture (b') consisting of the following components was prepared.
Methyl methacrylate (methyl methacrylate) 97.5% by mass
n-Butyl acrylate (n-butyl acrylate) 2.5% by mass
　下記単量体混合物（ｂ’）を、溶液IIIに７８分間かけて連続的に添加した。さらに３
０分間重合反応を継続させて、メタクリル系重合体（ｂ）を得た。
　単量体混合物（ｂ’）　　　　　　　　　　　　　　　２６．１質量部 The following monomer mixture (b') was added continuously to solution III over a period of 78 minutes.
The polymerization reaction was continued for 10 minutes to obtain a methacrylic polymer (b).
Monomer mixture (b') 26.1 parts by mass
　得られたメタクリル系重合体（ｂ）を３質量％硫酸ナトリウム温水溶液中へ投入して、塩析・凝固させた。次いで、脱水・洗浄を繰り返した後、乾燥させて、３層構造のアクリル系グラフト共重合体粒子（ゴム粒子）Ｒ１を得た。
　得られたゴム粒子Ｒ１の平均粒子径を、ゼータ電位・粒径測定システム「ＥＬＳＺ－２０００ＺＳ」（大塚電子株式会社製）で測定したところ、２００ｎｍであった。また、ゴム粒子のガラス転移温度（Ｔｇ）は、－３０℃であった。 The obtained methacrylic polymer (b) was poured into a 3% by mass aqueous solution of sodium sulfate to cause salting out and coagulation. Then, after repeated dehydration and washing, the mixture was dried to obtain acrylic graft copolymer particles (rubber particles) R1 having a three-layer structure.
The average particle size of the obtained rubber particles R1 was measured by a zeta potential/particle size measuring system "ELSZ-2000ZS" (manufactured by Otsuka Electronics Co., Ltd.) and found to be 200 nm. The glass transition temperature (Tg) of the rubber particles was -30°C.
　（２．１．３）界面活性剤溶液の調製
　下記成分を混合、溶解し、界面活性剤溶液を調製した。
　メチルエチルケトン（ＭＥＫ）　　　　　　　　　　　　　９８質量部
　フォスファノールＭＬ－２２０（ポリオキシエチレンラウリルエーテルリン酸、東邦化学工業株式会社製）
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　２質量部 (2.1.3) Preparation of surfactant solution The following components were mixed and dissolved to prepare a surfactant solution.
Methyl ethyl ketone (MEK) 98 parts by weight Phosphanol ML-220 (polyoxyethylene lauryl ether phosphate, manufactured by Toho Chemical Industry Co., Ltd.)
2 parts by weight
　（２．１．４）ドープの調製
　窒素濃度を９８．５体積％、酸素濃度を１．５体積％に制御した溶解タンクに、溶剤として下記成分を投入した。
　メチルエチルケトン　　　　　　　　　　　　　　　　８５．３質量部
　次に、この溶剤の入った溶解タンクに、下記成分を投入し、３０分間攪拌を行った。
　界面活性剤溶液　　　　　　　　　　　　　　　　　　　　１５質量部
　着色剤Ｐ１　　　　　　　　　　　　　　　　　　　０．０１１質量部 (2.1.4) Preparation of Dope The following components were charged as a solvent into a dissolution tank in which the nitrogen concentration was controlled to 98.5 vol % and the oxygen concentration was controlled to 1.5 vol %.
Methyl ethyl ketone: 85.3 parts by mass Next, the components listed below were added to the dissolution tank containing this solvent, and the mixture was stirred for 30 minutes.
Surfactant solution 15 parts by weight Colorant P1 0.011 parts by weight
　その後、下記成分を攪拌しながら投入し、２３℃で１時間攪拌を続けゴム粒子（グラフト共重合体）を分散させた。
　ゴム粒子（グラフト共重合体粒子）　　　　　　　　　　２．２質量部
　そして、溶解タンクに、攪拌しながら下記成分を投入した後、２３℃で４時間攪拌し、固形分を完全に溶解し、ドープを完成させた。
　熱可塑性（メタ）アクリル系樹脂　　　　　　　　　　　８．８質量部 Thereafter, the following components were added with stirring, and stirring was continued at 23° C. for 1 hour to disperse the rubber particles (graft copolymer).
Rubber particles (graft copolymer particles) 2.2 parts by mass The following components were then charged into a dissolution tank with stirring, and the mixture was stirred at 23° C. for 4 hours to completely dissolve the solids, thereby completing the dope.
Thermoplastic (meth)acrylic resin 8.8 parts by mass
　（２．１．５）光学フィルムＢ１の形成
　基材として、ＰＥＴフィルム「ＴＮ１００」（東洋紡株式会社製、厚さ５０μｍ、非シリコーン系剥離剤を含有する離型層あり）を準備した。このＰＥＴフィルムの離型層上に、バックコート法によりダイスを用いて、ドープを塗布した後、溶剤濃度０．１８体積％の雰囲気下、８０℃で乾燥させた。そして、基材を剥離し、厚さ４０μｍの光学フィルムＢ１を得た。 (2.1.5) Formation of Optical Film B1 As a substrate, a PET film "TN100" (manufactured by Toyobo Co., Ltd., thickness 50 μm, with a release layer containing a non-silicone-based release agent) was prepared. A dope was applied onto the release layer of this PET film using a die by a backcoat method, and then dried at 80°C under an atmosphere with a solvent concentration of 0.18% by volume. Then, the substrate was peeled off to obtain an optical film B1 with a thickness of 40 μm.
　（２．２）光学フィルムＢ２～Ｂ１９の作製
　光学フィルムＢ１の作製において、樹脂の種類、ゴム粒子の種類及び含有量、着色剤の種類及び含有量、並びに光学フィルムの厚さを、表Ｉ～表IVに記載のとおりに変更した以外は同様の方法で、光学フィルムＢ２～Ｂ１９を作製した。 (2.2) Preparation of Optical Films B2 to B19 Optical films B2 to B19 were prepared in the same manner as in preparation of optical film B1, except that the type of resin, the type and content of rubber particles, the type and content of colorant, and the thickness of the optical film were changed as shown in Tables I to IV.
　（２．３）光学フィルムＢ２０の作製
　光学フィルムＢ１の作製において、基材としてのＰＥＴフィルムの代わりに、後述するガラス層１に直接ドープを塗布した以外は同様の方法で、光学フィルムＢ２０を作製した。 (2.3) Preparation of Optical Film B20 Optical film B20 was prepared in the same manner as in preparation of optical film B1, except that the dope was directly applied to glass layer 1 described below, instead of using a PET film as the substrate.
　（３）ガラス層（薄膜ガラス）の作製
　（３．１）ガラス層１の作製
　１２インチの寸法を有する薄膜ガラス１（ソーダライムガラス）を、下記工程にしたがって作製した。 (3) Preparation of Glass Layer (Thin Glass) (3.1) Preparation of Glass Layer 1 Thin glass layer 1 (soda lime glass) having a dimension of 12 inches was prepared according to the following steps.
　（工程１）接合面を有するキャリア基板上に、薄膜ガラスの第１の表面が接するように薄膜ガラスを作製した。そして、薄膜ガラスの第１の表面とは反対側の第２の表面に、接着力を有するコンタクト膜（「コンタクトフィルム」ともいう）を付着させた。
　（工程２）次いで、薄膜ガラスを、接着力の高いコンタクト膜によって、キャリア基板より剥離した。
　（工程３）コンタクト膜の接着力を弱める脆弱化処理（電磁放射線照射）によって、キャリア基板から剥離された薄膜ガラスの第２の表面から、コンタクト膜を除去した。 (Step 1) A thin film glass was prepared so that a first surface of the thin film glass was in contact with a carrier substrate having a bonding surface. Then, a contact film having adhesive force was attached to a second surface of the thin film glass opposite to the first surface.
(Step 2) The thin glass was then peeled off from the carrier substrate by the highly adhesive contact film.
(Step 3) The contact film was removed from the second surface of the thin glass peeled off from the carrier substrate by a weakening treatment (electromagnetic radiation exposure) that weakened the adhesive strength of the contact film.
　工程１によって、厚さ５００μｍのキャリア基板に接するように、また、所定の厚さとなるように薄膜ガラスを作製した後、下記コンタクト膜を付着させた。次いで、工程２によって、キャリア基板から、コンタクト膜と共に薄膜ガラスを、３０秒間で剥離した。
　なお、コンタクト膜は、市販品の「ＮＤＳ４１５０－２０」を使用した。「ＮＤＳ４１５０－２０」は、ポリオレフィン（ＰＯ）を含む厚さ１５０μｍのフィルムであり、さらに、厚さ１０μｍの接着剤層を有する。 In step 1, a thin glass film was prepared so as to be in contact with a carrier substrate having a thickness of 500 μm and to have a predetermined thickness, and then a contact film was attached to the thin glass film. Next, in step 2, the thin glass film together with the contact film was peeled off from the carrier substrate in 30 seconds.
The contact film used was a commercially available product, "NDS4150-20.""NDS4150-20" is a 150 μm thick film containing polyolefin (PO), and further has a 10 μm thick adhesive layer.
　次いで、工程３によって、露出したコンタクト膜を脆弱化処理して接着力を低下させた。脆弱化処理では、波長３６５ｎｍの紫外線を、コンタクト膜に１０秒間照射した。紫外線の照度は、５００ｍＷ／ｃｍ２、積算光量は５００ｍＪ／ｃｍ２であった。脆弱化処理前の接着力は、１１Ｎ／２５ｍｍであったが、脆弱化処理後の接着力は、０．４Ｎ／２５ｍｍに低減した。これにより、コンタクト膜を薄膜ガラスから容易に剥離することができ、厚さ３０μｍのガラス層１（薄膜ガラス１）を得た。 Next, in step 3, the exposed contact film was subjected to a weakening treatment to reduce the adhesive strength. In the weakening treatment, ultraviolet light with a wavelength of 365 nm was irradiated onto the contact film for 10 seconds. The illuminance of the ultraviolet light was 500 mW/cm 2 , and the cumulative amount of light was 500 mJ/cm 2 . The adhesive strength before the weakening treatment was 11 N/25 mm, but after the weakening treatment, the adhesive strength was reduced to 0.4 N/25 mm. This allowed the contact film to be easily peeled off from the thin glass, and a glass layer 1 (thin glass 1) with a thickness of 30 μm was obtained.
　（３．２）ガラス層２の作製
　ガラス層１の作製において、厚さを、１０μｍにした以外は同様の方法で、ガラス層２を作製した。 (3.2) Preparation of Glass Layer 2 Glass layer 2 was prepared in the same manner as in preparation of glass layer 1, except that the thickness was changed to 10 μm.
　（４）粘着層Ｃの作製
　（４．１）粘着層Ｃ１の作製
　（４．１．１）紫外線硬化型アクリル系粘着剤組成物（ａ－１）の調製
　下記成分からなるモノマー混合物を調製した。
　２－エチルヘキシルアクリレート（２ＥＨＡ）　　　　　　７８質量部
　Ｎ－ビニル－２－ピロリドン（ＮＶＰ）　　　　　　　　　１８質量部
　２－ヒドロキシエチルアクリレート（ＨＥＡ）　　　　　　　４質量部 (4) Preparation of Adhesive Layer C (4.1) Preparation of Adhesive Layer C1 (4.1.1) Preparation of UV-Curable Acrylic Adhesive Composition (a-1) A monomer mixture consisting of the following components was prepared.
2-Ethylhexyl acrylate (2EHA) 78 parts by weight N-vinyl-2-pyrrolidone (NVP) 18 parts by weight 2-hydroxyethyl acrylate (HEA) 4 parts by weight
　そして、光重合開始剤として下記成分を添加した。
　１－ヒドロキシシクロヘキシルフェニルケトン　　　０．０３５質量部
　２，２－ジメトキシ－１，２－ジフェニルエタン－１－オン
　　　　　　　　　　　　　　　　　　　　　　　　　０．０３５質量部
　なお、光重合開始剤は下記の市販品を用いた。
　１－ヒドロキシシクロヘキシルフェニルケトン：「Ｏｍｎｉｒａｄ（登録商標）１８４」（波長２００～３７０ｎｍに吸収帯を有する、ＩＧＭ　Ｒｅｓｉｎｓ　Ｂ．Ｖ．社製）
　２，２－ジメトキシ－１，２－ジフェニルエタン－１－オン：「Ｏｍｎｉｒａｄ（登録商標）６５１」（波長２００～３８０ｎｍに吸収帯を有する、ＩＧＭ　Ｒｅｓｉｎｓ　Ｂ．Ｖ．社製） Then, the following components were added as photopolymerization initiators.
1-Hydroxycyclohexyl phenyl ketone 0.035 parts by mass 2,2-Dimethoxy-1,2-diphenylethan-1-one 0.035 parts by mass The following commercially available photopolymerization initiator was used.
1-Hydroxycyclohexyl phenyl ketone: "Omnirad (registered trademark) 184" (having an absorption band in the wavelength range of 200 to 370 nm, manufactured by IGM Resins B.V.)
2,2-Dimethoxy-1,2-diphenylethan-1-one: "Omnirad (registered trademark) 651" (having an absorption band in the wavelength range of 200 to 380 nm, manufactured by IGM Resins B.V.)
　その後、粘度（計測条件：ＢＨ粘度計Ｎｏ．５ローター、１０ｒｐｍ、測定温度３０℃）が、約２０Ｐａ・ｓになるまで紫外線を照射した。そして、上記モノマー成分の一部が重合したプレポリマー組成物（重合率：８％）を得た。 Then, ultraviolet light was applied until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s. A prepolymer composition (polymerization rate: 8%) in which some of the monomer components were polymerized was obtained.
　次に、当該プレポリマー組成物に、下記成分を添加して混合し、アクリル系粘着剤組成物を得た。
　ヘキサンジオールジアクリレート（ＨＤＤＡ）　　　　０．１５質量部
　シランカップリング剤「ＫＢＭ－４０３」（信越化学工業株式会社製）
　　　　　　　　　　　　　　　　　　　　　　　　　　　０．３質量部 Next, the following components were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition.
Hexanediol diacrylate (HDDA) 0.15 parts by mass Silane coupling agent "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.)
0.3 parts by weight
　得られたアクリル系粘着剤組成物に、下記成分を添加し攪拌することにより、紫外線硬化型アクリル系粘着剤組成物（ａ－１）を得た。
　２，４－ビス－［｛４－（４－エチルヘキシルオキシ）－４－ヒドロキシ｝－フェニル］－６－（４－メトキシフェニル）－１，３，５－トリアジン
　（固形分濃度が１５質量％となるようにｎ－ブチルアクリレートに溶解して添加）
　　　　　　　　　　　　　　　　　　　　　　　　　　　１．４質量部
　ビス（２，４，６－トリメチルベンゾイル）－フェニルフォスフィンオキサイド
　　　　　　　　　　　　　　　　　　　　　　　　　　　０．２質量部
　なお、下記の市販品を用いた。
　２，４－ビス－［｛４－（４－エチルヘキシルオキシ）－４－ヒドロキシ｝－フェニル］－６－（４－メトキシフェニル）－１，３，５－トリアジン：「Ｔｉｎｏｓｏｒｂ（登録商標）Ｓ」（ＢＡＳＦジャパン株式会社製）
　ビス（２，４，６－トリメチルベンゾイル）－フェニルフォスフィンオキサイド：「Ｏｍｎｉｒａｄ（登録商標）８１９」（波長２００～４５０ｎｍに吸収帯を有する、ＩＧＭ　Ｒｅｓｉｎｓ　Ｂ．Ｖ．社製） The following components were added to the obtained acrylic pressure-sensitive adhesive composition and stirred to obtain an ultraviolet-curable acrylic pressure-sensitive adhesive composition (a-1).
2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (dissolved in n-butyl acrylate to give a solids concentration of 15% by mass and added)
1.4 parts by mass Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide 0.2 parts by mass The following commercially available products were used.
2,4-Bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine: "Tinosorb (registered trademark) S" (manufactured by BASF Japan Ltd.)
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: "Omnirad (registered trademark) 819" (having an absorption band in the wavelength range of 200 to 450 nm, manufactured by IGM Resins B.V.)
　（４．１．２）粘着層Ｃ１の形成
　得られた紫外線硬化型アクリル系粘着剤組成物（ａ－１）を、離型フィルムの面上に、硬化後の厚さが５μｍとなるように塗布し、さらに、その表面に離型フィルムを貼り合わせた。その後、照度：６．５ｍＷ／ｃｍ２、積算光量：１５００ｍＪ／ｃｍ２の条件で紫外線照射を行い、組成物を硬化させて、離型フィルムを剥離し、粘着層Ｃ１を形成した。 (4.1.2) Formation of adhesive layer C1 The obtained ultraviolet-curable acrylic adhesive composition (a-1) was applied onto the surface of a release film so that the thickness after curing was 5 μm, and a release film was then attached to the surface. Thereafter, ultraviolet light was irradiated under conditions of illuminance: 6.5 mW/cm 2 and cumulative light amount: 1500 mJ/cm 2 to cure the composition, and the release film was peeled off to form an adhesive layer C1.
　（４．２）粘着層Ｃ２及びＣ３の作製
　粘着層Ｃ１の作製において、更に着色剤を添加し、着色剤の種類及び含有量を、表Ｉ～表IVに記載のとおりに変更した以外は同様の方法で、粘着層Ｃ２及びＣ３を作製した。 (4.2) Preparation of Adhesive Layers C2 and C3 Adhesive layers C2 and C3 were prepared in the same manner as in the preparation of adhesive layer C1, except that a colorant was further added and the type and content of the colorant were changed as shown in Tables I to IV.
　（５）粘着層Ｄの作製
　（５．１）粘着層Ｄ１の作製
　粘着層Ｃ１の作製で得られた紫外線硬化型アクリル系粘着剤組成物（ａ－１）を、上記で得られた光学フィルムＢの面上に、硬化後の厚さが５μｍとなるように塗布し、さらに、その表面に離型フィルムを貼り合わせた。その後、照度：６．５ｍＷ／ｃｍ２、積算光量：１５００ｍＪ／ｃｍ２の条件で紫外線照射を行い、組成物を硬化させて、離型フィルムを剥離し、光学フィルムＢ上に粘着層Ｄ１を形成した。 (5) Preparation of adhesive layer D (5.1) Preparation of adhesive layer D1 The ultraviolet-curable acrylic adhesive composition (a-1) obtained in the preparation of adhesive layer C1 was applied onto the surface of optical film B obtained above so that the thickness after curing was 5 μm, and a release film was further attached to the surface. Thereafter, ultraviolet irradiation was performed under conditions of illuminance: 6.5 mW/cm 2 and accumulated light amount: 1500 mJ/cm 2 to cure the composition, and the release film was peeled off to form adhesive layer D1 on optical film B.
　粘着層Ｄ１の２５℃における貯蔵弾性率は、８．００ＭＰａであった。
　なお、粘着層Ｄのサンプルは、光学フィルムの代わりに離型フィルムの面上に、同様の方法で粘着層Ｄを形成し、その後離型フィルムを剥離することにより作製した。そして、貯蔵弾性率を測定した。 The storage modulus of the adhesive layer D1 at 25° C. was 8.00 MPa.
A sample of the adhesive layer D was prepared by forming the adhesive layer D on the surface of a release film instead of the optical film in the same manner, and then peeling off the release film. Then, the storage modulus was measured.
　（５．２）粘着層Ｄ２及びＤ３の作製
　粘着層Ｄ１の作製において、厚さ及び貯蔵弾性率を、表Ｉ～表IVに記載のとおりに変更した以外は同様の方法で、粘着層Ｄ２及びＤ３を作製した。
　なお、２５℃における貯蔵弾性率は、それぞれ０．５ＭＰａ、１１．００ＭＰａであった。貯蔵弾性率は、紫外線の照射条件を変更することにより調整した。 (5.2) Preparation of Adhesive Layers D2 and D3 Adhesive layers D2 and D3 were prepared in the same manner as in the preparation of adhesive layer D1, except that the thickness and storage modulus were changed as shown in Tables I to IV.
The storage modulus at 25° C. was 0.5 MPa and 11.00 MPa, respectively. The storage modulus was adjusted by changing the ultraviolet ray irradiation conditions.
　（６）積層体の作製
　（６．１）積層体１の作製
　上記で得られた光学フィルムＡ１、薄膜ガラス１、粘着層Ｄ１を有する光学フィルムＢ１、及び粘着層Ｃ１を貼り合わせた。そして、光学フィルムＡ１、薄膜ガラス１、粘着層Ｄ１、光学フィルムＢ１、粘着層Ｃ１の順で配置される積層体１を得た。 (6) Preparation of Laminate (6.1) Preparation of Laminate 1 The optical film A1 obtained above, the thin glass 1, the optical film B1 having the adhesive layer D1, and the adhesive layer C1 were laminated together to obtain a laminate 1 in which the optical film A1, the thin glass 1, the adhesive layer D1, the optical film B1, and the adhesive layer C1 were arranged in this order.
　（６．２）積層体２～２５及び２７～２９の作製
　表Ｉ～表IVに記載の組み合わせとなるよう、光学フィルムＡ、薄膜ガラス、粘着層Ｄ、光学フィルムＢ及び粘着層Ｃを貼り合わせ、積層体２～２５及び２７～２９を得た。 (6.2) Preparation of Laminates 2 to 25 and 27 to 29 The optical film A, the thin glass, the adhesive layer D, the optical film B and the adhesive layer C were laminated together to obtain the combinations shown in Tables I to IV, to obtain laminates 2 to 25 and 27 to 29.
　（６．３）積層体２６の作製
　上記で得られた光学フィルムＡ１、光学フィルムＢ２０を有する薄膜ガラス１、及び粘着層Ｃ１を貼り合わせた。そして、光学フィルムＡ１、薄膜ガラス１、光学フィルムＢ１、粘着層Ｃ１の順で配置される積層体２６を得た。 (6.3) Preparation of Laminate 26 The optical film A1 obtained above, the thin film glass 1 having the optical film B20, and the adhesive layer C1 were bonded together to obtain a laminate 26 in which the optical film A1, the thin film glass 1, the optical film B1, and the adhesive layer C1 were arranged in this order.
　２．評価
　得られた積層体について、下記評価を行った。 2. Evaluation The obtained laminate was evaluated as follows.
　（１）反射率の測定
　得られた各積層体を、粘着層Ｃを介して、有機ＥＬパネルの視認側に貼り合わせた。そして、有機ＥＬパネルに黒画像を表示させ、分光測色計「ＣＭ－２６００ｄ」（コニカミノルタ社製）を用いて、正面反射率を測定し、下記の基準で評価した。なお、評価がＡ以上（Ａ～ＡＡＡ）であれば、実用可能である。
　ＡＡＡ：１．５以下である。
　　ＡＡ：１．５超、１．６以下である。
　　　Ａ：１．６超、１．７以下である。
　　　Ｂ：１．７超、１．８以下である。
　　　Ｃ：１．８超である。 (1) Measurement of reflectance Each of the obtained laminates was attached to the viewing side of an organic EL panel via the adhesive layer C. Then, a black image was displayed on the organic EL panel, and the front reflectance was measured using a spectrophotometer "CM-2600d" (manufactured by Konica Minolta), and evaluated according to the following criteria. Note that if the evaluation is A or higher (A to AAA), it is usable.
AAA: 1.5 or less.
AA: greater than 1.5 and equal to or less than 1.6.
A: More than 1.6 and 1.7 or less.
B: More than 1.7 and 1.8 or less.
C: greater than 1.8.
　（２）コントラストの測定
　上記で得られた光学フィルムＡ１、薄膜ガラス１、及び粘着層Ｄ１を有する光学フィルムＢ１を貼り合わせた。そして、光学フィルムＡ１、薄膜ガラス１、粘着層Ｄ１、光学フィルムＢ１の順で配置される、すなわち、粘着層Ｃを除く、折り曲げ試験用サンプルを作製した。
　当該サンプルを、直径３ｍｍで無荷重折り曲げ試験を３０万回行った後、粘着層Ｃを介して、有機ＥＬパネルの視認側に貼り合わせた。
　ｉ）有機ＥＬパネルを白表示させたときの表示画面の、１ｍ離れた距離からの正面輝度（表示画面の法線方向から測定される輝度）を、分光放射輝度計「ＣＳ２０００」（コニカミノルタセンシング製）で測定した。同様にして、有機ＥＬパネルを黒表示させたときの表示画面の正面輝度を測定した。
　ii）下記式で算出される、黒表示させたときの表示画面の正面輝度に対する、白表示させたときの表示画面の正面輝度の比の値を、「正面コントラスト」とした。
　式：　正面コントラスト＝（白表示させたときの正面輝度）／（黒表示させたときの正面輝度）
　iii）有機ＥＬパネルの表示画面の任意の１０点における正面コントラストを測定し、それらの算術平均値を求めた。そして、下記の基準で評価した。なお、評価がＡ以上（Ａ～ＡＡＡ）であれば、実用可能である。
　ＡＡＡ：正面コントラストが、２０００以上である。
　　ＡＡ：正面コントラストが、１７００以上、２０００未満である。
　　　Ａ：正面コントラストが、１５００以上、１７００未満である。
　　　Ｂ：正面コントラストが、１３００以上、１５００未満である。
　　　Ｃ：正面コントラストが、１３００未満である。 (2) Measurement of contrast The optical film A1 obtained above, the thin glass 1, and the optical film B1 having the adhesive layer D1 were laminated together. Then, a sample for bending test was prepared in which the optical film A1, the thin glass 1, the adhesive layer D1, and the optical film B1 were arranged in this order, i.e., excluding the adhesive layer C.
The sample was subjected to a no-load bending test 300,000 times at a diameter of 3 mm, and then attached to the viewing side of an organic EL panel via adhesive layer C.
i) The front luminance (luminance measured from the normal direction of the display screen) of the display screen when the organic EL panel was displayed white was measured from a distance of 1 m using a spectroradiometer "CS2000" (manufactured by Konica Minolta Sensing Co., Ltd.) Similarly, the front luminance of the display screen when the organic EL panel was displayed black was measured.
ii) The ratio of the front luminance of the display screen when white is displayed to the front luminance of the display screen when black is displayed, calculated by the following formula, was defined as the "front contrast".
Formula: Front contrast = (front luminance when white is displayed) / (front luminance when black is displayed)
iii) The front contrast was measured at any 10 points on the display screen of the organic EL panel, and the arithmetic mean value was calculated. Then, the contrast was evaluated according to the following criteria. If the evaluation was A or higher (A to AAA), the panel was deemed usable.
AAA: The front contrast is 2000 or more.
AA: The front contrast is 1,700 or more and less than 2,000.
A: The front contrast is 1,500 or more and less than 1,700.
B: The front contrast is 1,300 or more and less than 1,500.
C: The front contrast is less than 1,300.
　（３）ペンドロップ試験（耐衝撃性）
　得られた各積層体を、サンハヤト株式会社製のベークライト基板上に、粘着層Ｃと基板とが接するようにして、また、光学フィルムＡの面が上になるようにして配置した。ペン先半径（Ｒ）０．３５ｍｍ、質量（ｍ）１２ｇのボールペンを、落下高さを変えながら光学フィルムＡの面に落とし、薄膜ガラスが割れたときの高さを、下記の基準で評価した。なお、評価がＤであれば実用不可であり、Ｃ以上（Ｃ～ＡＡＡ）であれば、実用可能である。評価がＢ又はＣであれば、耐衝撃性に優れるとまではいえないが、実用上問題のない程度であるといえる。さらに、評価がＡ以上（Ａ～ＡＡＡ）であれば、耐衝撃性に特化しているといえる。
　ＡＡＡ：３０ｃｍから落とした際も割れない。
　　ＡＡ：２５ｃｍから落とした際は割れないが、３０ｃｍから落とした際は割れる。
　　　Ａ：１５ｃｍから落とした際は割れないが、２５ｃｍから落とした際は割れる。
　　　Ｂ：１０ｃｍから落とした際は割れないが、１５ｃｍから落とした際は割れる。
　　　Ｃ：１０ｃｍから落とした際に顕微鏡で微小な割れが確認できる。
　　　Ｄ：１０ｃｍから落とした際に目視で割れが確認できる。 (3) Pen drop test (impact resistance)
Each of the obtained laminates was placed on a Bakelite substrate manufactured by Sanhayato Co., Ltd., so that the adhesive layer C was in contact with the substrate, and the surface of the optical film A was placed on top. A ballpoint pen with a pen tip radius (R) of 0.35 mm and a mass (m) of 12 g was dropped onto the surface of the optical film A while changing the drop height, and the height at which the thin glass broke was evaluated according to the following criteria. If the evaluation was D, it was not practical, and if it was C or higher (C to AAA), it was practical. If the evaluation was B or C, it could not be said that the impact resistance was excellent, but it could be said that there was no problem in practical use. Furthermore, if the evaluation was A or higher (A to AAA), it could be said that it was specialized in impact resistance.
AAA: Will not break even when dropped from 30cm.
AA: It will not break if dropped from 25 cm, but will break if dropped from 30 cm.
A: It won't break if dropped from 15cm, but it will break if dropped from 25cm.
B: It does not break when dropped from 10 cm, but it breaks when dropped from 15 cm.
C: When dropped from 10 cm, tiny cracks were visible under a microscope.
D: Cracks are visible when dropped from 10 cm.
　積層体の各層の構成及び積層体の評価結果を、表Ｉ～表IVに示す。
　なお、「－」については、含有しないことを表す。 The configuration of each layer of the laminate and the evaluation results of the laminate are shown in Tables I to IV.
In addition, "-" indicates that it is not contained.
　また、表内の用語及び記号については、下記のとおりである。
　＜光学フィルム＞
　（樹脂）
　ＴＡＣ：トリアセチルセルロース
　アクリル：上記熱可塑性（メタ）アクリル系樹脂
　ＰＥＴ：ポリエチレンテレフタレート
　ＣＯＰ：シクロオレフィン樹脂「アートンＧ７８１０（ＪＳＲ株式会社製）
　（ゴム粒子）
　Ｒ１：上記で得られたゴム粒子
　（着色剤）
　Ｐ１：「Ｋａｙａｓｅｔ　Ｂｌａｃｋ　Ａ－Ｎ」（日本化薬株式会社製）
　Ｐ２：「ＮＵＢＩＡＮ　ＢＬＡＣＫ　ＰＣ－５８５７」（オリエント化学工業株式会社製） The terms and symbols in the table are as follows:
<Optical film>
(resin)
TAC: triacetyl cellulose Acrylic: the above thermoplastic (meth)acrylic resin PET: polyethylene terephthalate COP: cycloolefin resin "Arton G7810 (manufactured by JSR Corporation)
(Rubber particles)
R1: Rubber particles obtained above (colorant)
P1: "Kayaset Black A-N" (manufactured by Nippon Kayaku Co., Ltd.)
P2: "NUBIAN BLACK PC-5857" (manufactured by Orient Chemical Industry Co., Ltd.)
　＜粘着層＞
　（着色剤）
　Ｐ１：「Ｋａｙａｓｅｔ　Ｂｌａｃｋ　Ａ－Ｎ」（日本化薬株式会社製）
　Ｐ３：「ＦＤＲ－００３」（山田化学工業株式会社製） <Adhesive layer>
(Coloring Agent)
P1: "Kayaset Black A-N" (manufactured by Nippon Kayaku Co., Ltd.)
P3: "FDR-003" (Yamada Chemical Co., Ltd.)
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　なお、各積層体において、光学フィルムＡと薄膜ガラスは、粘着剤を介して貼り合わせたが、粘着剤の種類によらず、同様の結果が得られた。また、積層体２６において、粘着層Ｃ１の代わりに異なる粘着剤を用いても、積層体２６と同様の結果が得られた。 In each laminate, the optical film A and the thin glass were bonded together via an adhesive, but similar results were obtained regardless of the type of adhesive. Also, in laminate 26, even when a different adhesive was used instead of adhesive layer C1, similar results were obtained.
　実施例と比較例から、本発明の積層体は、反射率（外光反射の抑制）と、コントラスト（屈曲後の良好なコントラスト）を両立できることがわかる。 The examples and comparative examples show that the laminate of the present invention can achieve both reflectance (suppression of external light reflection) and contrast (good contrast after bending).
　実施例１～３及び６の比較から、ＴＡが、７０～８５％の範囲内であることにより、反射率とコントラストを両立できることがわかる。 From a comparison of Examples 1 to 3 and 6, it is seen that by setting T A within the range of 70 to 85%, it is possible to achieve both a good reflectance and a good contrast.
　実施例１、２及び６の比較から、ＴＢが、７０～８５％の範囲内であることにより、反射率とコントラストを両立できることがわかる。 From a comparison of Examples 1, 2 and 6, it is seen that by setting T B within the range of 70 to 85%, it is possible to achieve both a good reflectance and a good contrast.
　実施例１、１５及び１６の比較から、少なくとも、光学フィルムＢが、ゴム粒子を含有することにより、耐衝撃性が向上することがわかる。 A comparison of Examples 1, 15, and 16 shows that at least optical film B has improved impact resistance due to the inclusion of rubber particles.
　実施例１７～２０の比較から、ゴム粒子の含有量が、光学フィルムＢの全質量に対して、１０～８０質量％の範囲内であることにより、耐衝撃性が向上することがわかる。 A comparison of Examples 17 to 20 shows that impact resistance is improved when the rubber particle content is within the range of 10 to 80 mass % relative to the total mass of optical film B.
　実施例２２～２５の比較から、光学フィルムＢの厚さが、１５～５０μｍの範囲内であることにより、コントラスト及び耐衝撃性が向上することがわかる。 A comparison of Examples 22 to 25 shows that contrast and impact resistance are improved by setting the thickness of optical film B within the range of 15 to 50 μm.
　実施例１１から、ガラス層の厚さが１０μｍの場合でも、反射率、コントラスト及び耐衝撃性が良好であることがわかる。 Example 11 shows that even when the glass layer is 10 μm thick, the reflectance, contrast, and impact resistance are good.
　実施例１及び７の比較から、ＴＣをＴＢよりも大きくする（上記式（２）を満たす）ことにより、コントラスト及び耐衝撃性が向上することがわかる。 From a comparison between Examples 1 and 7, it can be seen that by making T C larger than T B (satisfying the above formula (2)), the contrast and impact resistance are improved.
　実施例１、９、１０及び２６の比較から、粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内であることにより、耐衝撃性が向上することがわかる。 Comparing Examples 1, 9, 10 and 26, it can be seen that impact resistance is improved when the storage modulus of adhesive layer D at 25°C is within the range of 0.5 to 8 MPa.
　本発明を用いることにより、外光反射の抑制と屈曲後の良好なコントラストを両立させたカバーユニットを提供できる。その結果、繰り返し折り畳んで使用しても良好な視認性を維持できるフレキシブルディスプレイを提供できる。 By using this invention, it is possible to provide a cover unit that suppresses external light reflection while providing good contrast after bending. As a result, it is possible to provide a flexible display that can maintain good visibility even when repeatedly folded and used.
　　１　光学フィルムＡ
　　２　光学フィルムＢ
　　３　ガラス層
　　４　粘着層Ｃ
　　５　粘着層Ｄ
　１０　積層体
　２０　積層体
　２１　キャリア基板
　２２　薄膜ガラス
　２３　コンタクト膜
　２４　電磁放射線
　３０　積層体
１００　表示装置
１０１　有機ＥＬ層
１１０　表示装置 1 Optical film A
2 Optical film B
3 Glass layer 4 Adhesive layer C
5 Adhesive layer D
REFERENCE SIGNS LIST 10 Laminate 20 Laminate 21 Carrier substrate 22 Thin glass 23 Contact film 24 Electromagnetic radiation 30 Laminate 100 Display device 101 Organic EL layer 110 Display device

Claims (12)

  1. 　少なくとも、光学フィルムＡ、光学フィルムＢ及びガラス層を有する積層体であって、
    　前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢの順で配置され、
    　前記光学フィルムＡ及び前記光学フィルムＢの、３８０～７８０ｎｍの波長領域における平均光透過率を、それぞれ、ＴＡ及びＴＢとしたとき、前記ＴＡ及び前記ＴＢが、下記式（１）を満たし、かつ前記ＴＡ及び前記ＴＢが、共に３９～８９％の範囲内である
    　式（１）：　ＴＡ＞ＴＢ
    　ことを特徴とする積層体。     A laminate having at least an optical film A, an optical film B, and a glass layer,
    the optical film A, the glass layer, and the optical film B are arranged in this order;
    When the average light transmittances of the optical film A and the optical film B in the wavelength region of 380 to 780 nm are T A and T B , respectively, the T A and the T B satisfy the following formula (1) and both the T A and the T B are within a range of 39 to 89%. Formula (1): T A >T B
    A laminate comprising:
  2. 　前記ＴＡが、７０～８５％の範囲内である
    　ことを特徴とする請求項１に記載の積層体。     2. The laminate according to claim 1, wherein the T A is in the range of 70 to 85%.
  3. 　前記ＴＢが、７０～８５％の範囲内である
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     3. The laminate according to claim 1, wherein the T B is in the range of 70 to 85%.
  4. 　少なくとも、前記光学フィルムＢが、ゴム粒子を含有する
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     The laminate according to claim 1 or 2, wherein at least the optical film B contains rubber particles.
  5. 　前記ゴム粒子の含有量が、前記光学フィルムＢの全質量に対して、１０～８０質量％の範囲内である
    　ことを特徴とする請求項４に記載の積層体。     5. The laminate according to claim 4, wherein the content of the rubber particles is within a range of 10 to 80 mass % with respect to the total mass of the optical film B.
  6. 　前記光学フィルムＢが、熱可塑性（メタ）アクリル系樹脂を含有する
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     The laminate according to claim 1 or 2, wherein the optical film B contains a thermoplastic (meth)acrylic resin.
  7. 　前記光学フィルムＢの厚さが、１５～５０μｍの範囲内である
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     3. The laminate according to claim 1, wherein the optical film B has a thickness in the range of 15 to 50 μm.
  8. 　前記ガラス層の厚さが、１０～３０μｍの範囲内である
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     3. The laminate according to claim 1, wherein the glass layer has a thickness in the range of 10 to 30 μm.
  9. 　当該積層体が、粘着層Ｃを更に有し、
    　前記光学フィルムＡ、前記ガラス層、前記光学フィルムＢ、前記粘着層Ｃの順で配置され、
    　前記粘着層Ｃの３８０～７８０ｎｍの波長領域における平均光透過率をＴＣとしたとき、前記ＴＢ及び前記ＴＣが、下記式（２）を満たす
    　式（２）：　ＴＢ＜ＴＣ
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     The laminate further has an adhesive layer C,
    The optical film A, the glass layer, the optical film B, and the adhesive layer C are arranged in this order,
    When the average light transmittance of the adhesive layer C in the wavelength region of 380 to 780 nm is defined as T C , the T B and the T C satisfy the following formula (2): T B <T C
    3. The laminate according to claim 1 or 2.
  10. 　当該積層体が、粘着層Ｄを更に有し、
    　前記光学フィルムＡ、前記ガラス層、前記粘着層Ｄ、前記光学フィルムＢの順で配置され、
    　前記粘着層Ｄの２５℃における貯蔵弾性率が、０．５～８ＭＰａの範囲内である
    　ことを特徴とする請求項１又は請求項２に記載の積層体。     The laminate further has an adhesive layer D,
    The optical film A, the glass layer, the adhesive layer D, and the optical film B are arranged in this order,
    3. The laminate according to claim 1, wherein the adhesive layer D has a storage modulus at 25° C. in the range of 0.5 to 8 MPa.
  11. 　請求項１又は請求項２に記載の積層体を具備する
    　ことを特徴とする表示装置。     A display device comprising the laminate according to claim 1 or 2.
  12. 　前記光学フィルムＡが、前記光学フィルムＢよりも当該表示装置の視認側に配置される
    　ことを特徴とする請求項１１に記載の表示装置。     The display device according to claim 11 , wherein the optical film A is disposed on a viewing side of the display device relative to the optical film B.
PCT/JP2023/041404 2022-11-29 2023-11-17 Laminate and display device WO2024116892A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007010834A (en) * 2005-06-29 2007-01-18 Sumitomo Chemical Co Ltd Substrate for display, and display element using it
JP2009279926A (en) * 2008-04-24 2009-12-03 Nitto Denko Corp Flexible substrate
JP2016039135A (en) * 2014-08-06 2016-03-22 三菱化学株式会社 Flexible substrate, organic el element using the same, and organic el luminaire
WO2017066924A1 (en) * 2015-10-20 2017-04-27 Schott Glass Technologies (Suzhou) Co. Ltd. Method for post-processing of bonded article
JP2019031100A (en) * 2018-11-01 2019-02-28 日東電工株式会社 Laminate
JP2022028479A (en) * 2020-08-03 2022-02-16 日東電工株式会社 Multilayer structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007010834A (en) * 2005-06-29 2007-01-18 Sumitomo Chemical Co Ltd Substrate for display, and display element using it
JP2009279926A (en) * 2008-04-24 2009-12-03 Nitto Denko Corp Flexible substrate
JP2016039135A (en) * 2014-08-06 2016-03-22 三菱化学株式会社 Flexible substrate, organic el element using the same, and organic el luminaire
WO2017066924A1 (en) * 2015-10-20 2017-04-27 Schott Glass Technologies (Suzhou) Co. Ltd. Method for post-processing of bonded article
JP2019031100A (en) * 2018-11-01 2019-02-28 日東電工株式会社 Laminate
JP2022028479A (en) * 2020-08-03 2022-02-16 日東電工株式会社 Multilayer structure

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