Layered optical film

Abstract

In this layered optical film, an optical film 1, an adhesive layer, and an optical film 2 are laminated in this order. The adhesive layer is formed of an active energy ray-curable adhesive composition containing an oxime ester-based photoinitiator. At least one of the optical films 1 and 2 is an optical film having ultraviolet absorption ability. This layered optical film has excellent adhesiveness even when an optical film having ultraviolet absorption ability is affixed.

Description

Laminated Optical Film

[0001] The present invention relates to a laminated optical film.

[0002] Conventionally, dyed polyvinyl alcohol films (containing dichroic substances such as iodine and dichroic dyes) have been used as polarizers for various image display devices, such as liquid crystal display devices and organic EL display devices, because they have both high transmittance and high polarization degree. The polarizers are produced by subjecting a polyvinyl alcohol film to various treatments, such as dyeing, crosslinking, and stretching, in a bath (treatment bath), followed by drying. Furthermore, polarizers are typically used as polarizing films (polarizing plates) with an optical film, such as triacetyl cellulose, bonded to one or both sides of the polarizer using an adhesive.

[0003] As adhesives for optical films, aqueous adhesive compositions and active energy ray-curable adhesive compositions are widely known, and optical films having ultraviolet absorbing properties are sometimes used for the above-mentioned optical films. In such embodiments, Patent Document 1 discloses that a dry-and-solidify type adhesive such as an aqueous adhesive is suitable because an amount of ultraviolet light sufficient for curing the adhesive is absorbed by the optical film having ultraviolet absorbing properties.

[0004] Furthermore, Patent Document 2 describes that, from the viewpoint of productivity, since a drying step of the adhesive composition can be eliminated, an active energy ray-curable adhesive composition is preferable to an aqueous adhesive composition, and further proposes that in the above-mentioned embodiment, a visible light-curable adhesive composition containing a photopolymerization initiator that is highly sensitive to light of 380 nm or more be used.

[0005] JP 2022-44293 A JP 2022-58639 A

[0006] However, from the viewpoint of adhesiveness, there has been a demand for an active energy ray-curable adhesive composition for optical films that differs from the above compositions.

[0007] In view of the above circumstances, an object of the present invention is to provide a laminated optical film that has excellent adhesiveness even when an optical film having ultraviolet absorbing ability is laminated thereto.

[0008] That is, the present invention relates to a laminated optical film in which an optical film 1, an adhesive layer, and an optical film 2 are laminated in this order, the adhesive layer being formed from an active energy ray-curable adhesive composition containing an oxime ester-based photopolymerization initiator, and at least one of the optical films 1 and 2 being an optical film having ultraviolet absorbing ability.

[0009] In the laminated optical film of the present invention, the optical film having ultraviolet absorbing ability preferably has a transmittance of 10% or less for light of 380 nm.

[0010] In the laminated optical film of the present invention, the active energy ray-curable adhesive composition preferably contains a sensitizer.

[0011] In the laminated optical film of the present invention, the sensitizer preferably contains an anthracene-based sensitizer.

[0012] In the laminated optical film of the present invention, the sensitizer preferably contains a naphthalene-based sensitizer.

[0013] In the laminated optical film of the present invention, the active energy ray adhesive composition may contain a photopolymerization initiator other than the oxime ester-based photopolymerization initiator.

[0014] Unlike conventional adhesive layers, the laminated optical film of the present invention has an adhesive layer formed from an active energy ray-curable adhesive composition containing an oxime ester-based photopolymerization initiator. Therefore, the adhesive is highly sensitive to active energy rays and generates highly reactive radical species, and therefore has excellent adhesive properties even when an optical film having ultraviolet absorbing ability is laminated thereto.

[0015] The laminated optical film of the present invention comprises an optical film 1, an adhesive layer, and an optical film 2 laminated in this order, the adhesive layer being formed from an active energy ray-curable adhesive composition containing an oxime ester-based photopolymerization initiator, and at least one of the optical films 1 and 2 being an optical film having ultraviolet absorbing ability.

[0016] <Active Energy Ray-Curable Adhesive Composition> The active energy ray-curable adhesive composition (hereinafter also simply referred to as "adhesive composition") contains an oxime ester-based photopolymerization initiator.

[0017] The active energy ray-curable adhesive compositions can be broadly classified into electron beam-curable, ultraviolet ray-curable, and visible light-curable adhesive compositions. Furthermore, the type of curing can be divided into radically polymerizable curable adhesive compositions and cationically polymerizable adhesive compositions. In the present invention, active energy rays with a wavelength range of 10 nm to less than 380 nm are referred to as ultraviolet rays, and active energy rays with a wavelength range of 380 nm to 800 nm are referred to as visible light. From the viewpoint of laminating an optical film with ultraviolet absorption ability, the active energy ray-curable adhesive composition that can be used in the present invention is preferably a visible light-curable adhesive composition that utilizes active energy rays with a wavelength of 380 nm or more.

[0018] <Oxime Ester Photopolymerization Initiator> The oxime ester photopolymerization initiator may be any oxime ester photopolymerization initiator that has an oxime ester skeleton in its molecule and is capable of absorbing active energy rays with a wavelength of 380 nm or more to generate radicals, from the viewpoint of laminating an optical film having ultraviolet absorption ability. Examples of the oxime ester photopolymerization initiator include compounds described in JP 2000-80068 A, JP 2001-233842 A, JP 2010-527339 A, JP 2010-527338 A, JP 2013-041153 A, and WO 2015 / 036910. Specific examples of the compound include 1,2-octanedione, 1-4-(phenylthio)-2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), and the like. In addition, commercially available products include compounds having a carbazole skeleton, such as Irgacure OXE-02 (manufactured by BASF), Adeka Arcles NCI-831 (manufactured by ADEKA Corporation), N-1919 (manufactured by ADEKA Corporation), TR-PBG-304 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.); compounds having a diphenyl sulfide skeleton, such as Irgacure OXE-01 (manufactured by BASF), Adeka Arcles NCI-930 (manufactured by ADEKA Corporation), TR-PBG-345 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.), TR-PBG-3057 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.); compounds having a fluorene skeleton, such as TR-PBG-365 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.). The oxime ester photopolymerization initiator can be used alone or in combination of two or more.

[0019] The amount of the oxime ester photopolymerization initiator may be appropriately set, and from the viewpoint of polymerization reaction, it is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the radical polymerizable compound described below. From the viewpoint of solubility, it is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the radical polymerizable compound described below.

[0020] The active energy ray-curable adhesive composition may contain a photopolymerization initiator other than the oxime ester-based photopolymerization initiator. Examples of such photopolymerization initiators include benzophenone-based compounds such as benzil, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α-hydroxycyclohexylphenyl ketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin methyl ether, benzyl benzoate, and the like. Examples of photopolymerization initiators other than the oxime ester-based initiators include benzoin alkyl ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxide; and acylphosphonate. The photopolymerization initiators other than the oxime ester-based photopolymerization initiators may be used singly or in combination of two or more.

[0021] The total blending amount of the oxime ester-based photopolymerization initiator and the photopolymerization initiator other than the oxime ester-based photopolymerization initiator may be set as appropriate, and is, for example, usually 20 parts by mass or less, preferably 1 to 15 parts by mass, and more preferably 3 to 10 parts by mass, relative to 100 parts by mass of the radical polymerizable compound described below.

[0022] In addition, the active energy ray-curable adhesive composition preferably contains a sensitizer from the viewpoint of enhancing adhesiveness.

[0023] <Sensitizer> The sensitizer may be any sensitizer that can transfer energy obtained by absorbing light to the oxime ester-based photopolymerization initiator to generate radicals from the photopolymerization initiator, and examples thereof include anthracene-based sensitizers, naphthalene-based sensitizers, benzoflavin-based sensitizers, perylene-based sensitizers, and thioxanthone-based sensitizers. One type of sensitizer can be used alone, or two or more types can be used in combination.

[0024] From the viewpoint of laminating an optical film having ultraviolet absorbing ability, the sensitizer is preferably a sensitizer capable of absorbing active energy rays having a wavelength of 380 nm or more, and from the viewpoint of sensitization ability, the anthracene-based sensitizer is particularly preferred. Examples of commercially available sensitizers include Anthracure UVS-1331 (manufactured by Air Water Performance Chemicals Inc.) and Anthracure UVS-581 (manufactured by Air Water Performance Chemicals Inc.).

[0025] The sensitizer preferably contains a naphthalene-based sensitizer, from the viewpoint of improving the energy conversion efficiency of the anthracene-based sensitizer that absorbs light. Examples of commercially available sensitizers include Anthracure UVS-2171 (manufactured by Air Water Performance Chemicals Inc.).

[0026] The amount of the sensitizer to be added may be set appropriately. From the viewpoint of sensitization, the amount is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 100 parts by mass or more, relative to 100 parts by mass of the oxime ester photopolymerization initiator. From the viewpoint of solubility, the amount is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less, relative to 100 parts by mass of the oxime ester photopolymerization initiator.

[0027] From the viewpoint of adhesiveness, it is preferable to use the anthracene-based sensitizer and the naphthalene-based sensitizer in combination as the sensitizer. In this case, the mass ratio of the anthracene-based sensitizer to the naphthalene-based sensitizer (anthracene-based sensitizer / naphthalene-based sensitizer) is preferably 0.1 to 1, and more preferably 0.3 to 0.8.

[0028] <Radical Polymerizable Compound> The radical polymerizable compound used in the adhesive composition includes a compound having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acryloyl group or a vinyl group. These curable components can be either monofunctional radically polymerizable compounds or polyfunctional radically polymerizable compounds having two or more functional groups. These radically polymerizable compounds can be used alone or in combination of two or more. Suitable examples of these radically polymerizable compounds are compounds having a (meth)acryloyl group. In the present invention, (meth)acryloyl refers to an acryloyl group and / or a methacryloyl group, and "(meth)" has the same meaning hereinafter.

[0029] <Monofunctional radical polymerizable compound> Examples of the monofunctional radical polymerizable compound include compounds represented by the formula (1): (In formula (1), R １ is a hydrogen atom or a methyl group, and R ２ and R ３ are each independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, or a cyclic ether group, and R ２ and R ３ may form a cyclic heterocycle.) The number of carbon atoms in the alkyl moiety of the alkyl group, hydroxyalkyl group, and / or alkoxyalkyl group is not particularly limited, but examples include those having 1 to 4 carbon atoms. ２ and R ３ Examples of the cyclic heterocycle that may be formed include N-acryloylmorpholine.

[0030] Specific examples of the compound represented by the above formula (1) include N-alkyl group-containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-methylol-N-propane(meth)acrylamide; and N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide. Examples of the cyclic ether group-containing (meth)acrylamide derivative include heterocycle-containing (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle, such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, etc. Among these, cyclic ether group-containing (meth)acrylamide derivatives are preferred, and N-hydroxyethylacrylamide and N-acryloylmorpholine are particularly preferred, in terms of excellent reactivity, ability to obtain a cured product with a high elastic modulus, and excellent adhesion to polarizers.

[0031] Furthermore, when a compound represented by the above formula (1) is used, the proportion of the above formula (1) in the radical polymerizable compound is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, from the viewpoint of affinity with the adherend, and is preferably 95% by mass or less, more preferably 90% by mass or more, and even more preferably 85% by mass or less, from the viewpoint of adhesive strength.

[0032] In addition to the above compounds, the active energy ray-curable adhesive composition may contain other monofunctional radically polymerizable compounds as curable components, from the viewpoint of enabling the adhesive composition to exhibit various functions. Examples of other monofunctional radically polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specific examples include (meth)acrylic acid (C1-20) alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0033] Examples of the (meth)acrylic acid derivatives include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl methyl (meth)acrylate, and methyl ... Examples of the alkoxy group- or phenoxy group-containing (meth)acrylates include polycyclic (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, and alkylphenoxy polyethylene glycol (meth)acrylate.

[0034] Examples of the (meth)acrylic acid derivatives include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate. (meth)acrylate, hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate; ) acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate and other halogen-containing (meth)acrylates; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate and other oxetane group-containing (meth)acrylates; (meth)acrylates having a heterocycle such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; hydroxypivalic acid neopentyl glycol (meth)acrylic acid adduct; and p-phenylphenol (meth)acrylate.

[0035] Other monofunctional radically polymerizable compounds include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0036] Furthermore, other monofunctional radically polymerizable compounds include, for example, lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and vinyl monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

[0037] In addition, as another monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acrylic group at the end or in the molecule, and also having an active methylene group. Examples of the active methylene group include an acetoacetyl group, an alkoxymalonyl group, and a cyanoacetyl group. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of the radically polymerizable compound having an active methylene group include acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; 2-ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, and N-(2-acetoacetylaminoethyl)acrylamide.

[0038] When the other monofunctional radical polymerizable compound is used, the proportion of the other monofunctional radical polymerizable compound in the radical polymerizable compound is usually about 30% by mass or less.

[0039] <Difunctional or More Polyfunctional Radically Polymerizable Compound> Examples of the difunctional or more polyfunctional radically polymerizable compound include polyfunctional (meth)acrylamide derivatives such as N,N'-methylenebis(meth)acrylamide, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether ... Examples of suitable (meth)acrylic acid esters include esters of (meth)acrylic acid and polyhydric alcohols such as 2-(meth)acryloyloxyethoxy)phenyl]fluorene, 2-(meth)acrylic acid esters ... Commercially available products include Aronix M-220 (manufactured by Toagosei Co., Ltd.), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer Co., Ltd.), CD-536 (manufactured by Sartomer Co., Ltd.), etc. Furthermore, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, various (meth)acrylate monomers, etc. may also be used, if necessary.

[0040] From the viewpoint of achieving both adhesion to the optical film and optical durability under harsh environments, it is preferable to use a combination of a monofunctional radically polymerizable compound and a polyfunctional radically polymerizable compound as the radically polymerizable compound. Since the monofunctional radically polymerizable compound has a relatively low liquid viscosity, its inclusion in the adhesive composition can reduce the liquid viscosity of the adhesive composition. Furthermore, it is preferable to include a polyfunctional radically polymerizable compound in the adhesive composition because it can three-dimensionally crosslink the cured product of the adhesive composition. When the polyfunctional radically polymerizable compound is used, the proportion of the polyfunctional radically polymerizable compound in the radically polymerizable compound is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less.

[0041] Furthermore, a polymerization initiation aid may be added as necessary. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate. When a polymerization initiation aid is used, the amount added is usually about 5 parts by mass or less per 100 parts by mass of the adhesive composition.

[0042] Furthermore, when a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound, it is preferable to use it in combination with a radical polymerization initiator having a hydrogen abstracting effect. This configuration significantly improves the adhesiveness of the adhesive layer of the polarized film, especially even immediately after removal from a high-humidity environment or water (non-dried state). Examples of the radical polymerization initiator having a hydrogen abstracting effect include thioxanthone-based radical polymerization initiators and benzophenone-based radical polymerization initiators. The radical polymerization initiator is preferably a thioxanthone-based radical polymerization initiator.

[0043] The active energy ray-curable adhesive composition may contain various additives as other optional components within the scope of the present invention, provided that the objectives and effects of the present invention are not impaired. Examples of such additives include polymers such as chlorinated polyolefins, epoxy resins, polyamides, polyamideimides, polyurethanes, polybutadiene, polychloroprene, polyethers, polyesters, styrene-butadiene block copolymers, petroleum resins, xylene resins, ketone resins, and cellulose resins; oligomers such as acrylic oligomers, fluorine-containing oligomers, silicone oligomers, and polysulfide oligomers; photoacid generators, photobase generators, silane coupling agents, polyrotaxanes, organometallic compounds, polymerization inhibitors, bubble suppressors, surfactants, plasticizers, UV absorbers, inorganic fillers, pigments, and dyes.

[0044] <Laminated Optical Film> The laminated optical film is formed by laminating, in order, an optical film 1, an adhesive layer formed from the active energy ray-curable adhesive composition, and an optical film 2, and at least one of the optical films 1 and 2 is an optical film having ultraviolet absorbing ability. The optical films 1 and 2 may be the same or different. Hereinafter, the optical films 1 and 2 will also be collectively referred to simply as "optical films."

[0045] The optical film having ultraviolet absorbing ability preferably has a transmittance of 20% or less, more preferably 10% or less, for light of 380 nm, from the viewpoint of protecting polarizers, liquid crystals, etc. from ultraviolet rays when the laminated optical film is incorporated into various image display devices. To impart ultraviolet absorbing ability to the optical film, for example, the material constituting the optical film may have ultraviolet absorbing ability, an ultraviolet absorber or the like may be added to the material constituting the optical film, or a surface treatment layer containing an ultraviolet absorber or the like may be laminated on the surface of the optical film.

[0046] Examples of the ultraviolet absorber include conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylate ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, triazine compounds, etc. Commercially available products include Adekastab LA-46 (manufactured by ADEKA Corporation), Adekastab LA-F70 (manufactured by ADEKA Corporation), KEMISORB102 (manufactured by Chemipro Chemicals), Chiguard 5405 (manufactured by Chitec Technology), Tinuvin 405 (manufactured by BASF Corporation), Tinuvin 460 (manufactured by BASF Corporation), Tinuvin 479 (manufactured by BASF Corporation), and Tinuvin 1600 (manufactured by BASF Corporation).

[0047] The optical films 1 and 2 are not particularly limited, and various transparent protective films used in various image display devices can be used. Examples of materials that can be used to form the transparent protective film include thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy. Examples of thermoplastic resins include cellulose ester resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins such as nylon and aromatic polyamide, polyimide resins, polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins) having a cyclo- or norbornene structure, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film can also be a cured layer formed from a thermosetting resin or ultraviolet-curable resin, such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone resin. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are suitable. The transparent protective film may contain any appropriate additives such as an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, an antistatic agent, a pigment, and a colorant.

[0048] The polycarbonate resin usually has at least one bond structure -CH ２ The polycarbonate resin is produced by reacting a dihydroxy compound having —O— with a carbonic acid diester in the presence of a polymerization catalyst. Preferably, the dihydroxy compound contains a structural unit derived from a dihydroxy compound represented by the following formula: Examples of such dihydroxy compounds include isosorbide, isomannide, and isoidet, which are stereoisomers. These may be used alone or in combination of two or more.

[0049] The polycarbonate resin may further contain structural units derived from dihydroxy compounds other than the dihydroxy compound represented by formula (2) (hereinafter, also simply referred to as "other dihydroxy compounds"). By further containing structural units derived from dihydroxy compounds other than the dihydroxy compound represented by formula (2), it becomes possible to improve ease of processing, heat resistance, impact resistance, etc.

[0050] Examples of other dihydroxy compounds include alicyclic dihydroxy compounds, aliphatic dihydroxy compounds, oxyalkylene glycols, aromatic dihydroxy compounds, and diols having a cyclic ether structure.

[0051] The alicyclic dihydroxy compound is not particularly limited, and is preferably a compound having a five-membered ring structure or a six-membered ring structure. The six-membered ring structure may be fixed into a chair or boat shape by a covalent bond. When the alicyclic dihydroxy compound has a five-membered ring structure or a six-membered ring structure, the heat resistance of the resulting polycarbonate can be improved. Examples of the alicyclic dihydroxy compound include cyclohexanedimethanols, tricyclodecane dimethanols, adamantanediols, and pentacyclopentadecanedimethanols. From the viewpoints of availability and ease of handling, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecane dimethanol are preferred.

[0052] Examples of the aliphatic dihydroxy compounds include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, and 1,6-hexanediol. Examples of the oxyalkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol. Examples of the aromatic dihydroxy compounds include 2,2-bis(4-hydroxyphenyl)propane [=bisphenol A], 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, and 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane. Examples of the diols having a cyclic ether structure include spiroglycols and dioxane glycols.

[0053] The proportion of the dihydroxy compound represented by formula (2) relative to all dihydroxy compounds constituting the polycarbonate resin is not particularly limited, but is preferably 10 mol% or more, more preferably 40 mol% or more, even more preferably 60 mol% or more, preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less. If the content of structural units derived from other dihydroxy compounds is too high, performance such as optical properties may be reduced.

[0054] When an alicyclic dihydroxy compound is used among the other dihydroxy compounds, the total proportion of the dihydroxy compound represented by formula (2) and the alicyclic dihydroxy compound relative to all dihydroxy compounds constituting the polycarbonate is not particularly limited, but is preferably 80 mol % or more, more preferably 90 mol % or more, and even more preferably 95 mol % or more.

[0055] The thickness of the transparent protective film can be determined as appropriate. In general, from the viewpoints of strength, workability such as handleability, thinness, etc., it is preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and even more preferably about 5 to 100 μm.

[0056] When the laminated optical film is used as a polarizing film, it is preferable that the optical film 1 is an optical film having the above-mentioned ultraviolet absorbing ability, and the optical film 2 is a polarizer. The polarizer may be a known polarizer formed by adsorbing and orienting a dichroic substance such as iodine or a dichroic dye on a polyvinyl alcohol-based film.

[0057] The transparent protective film can be a retardation plate having a front retardation of 40 nm or more and / or a thickness retardation of 80 nm or more. The front retardation is usually controlled to be in the range of 40 to 200 nm, and the thickness retardation is usually controlled to be in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as the transparent protective film, thereby enabling a thinner film to be achieved.

[0058] Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, and an oriented layer of a liquid crystal polymer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. The retardation plate may be used by being attached to a transparent protective film that does not have a retardation.

[0059] In the polarizing film, a functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, etc. may be provided on the surface of the transparent protective film to which the polarizer is not attached. The functional layer such as the hard coat layer, the anti-reflection layer, the anti-sticking layer, the diffusion layer, or the anti-glare layer may be provided on the protective film itself, or may be provided separately from the protective film.

[0060] In the laminated optical film, the active energy ray-curable adhesive composition is applied directly to optical film 1 and / or optical film 2, and after the optical film 1 and the optical film 2 are bonded together, the adhesive composition is irradiated with active energy rays (electron beams, ultraviolet rays, visible light, etc.) to cure the adhesive composition and form an adhesive layer. The active energy rays can be irradiated from any appropriate direction. However, since the active energy ray-curable adhesive composition of the present invention has excellent adhesive properties even when used to bond an optical film having ultraviolet absorption ability, it may be irradiated from the optical film side having ultraviolet absorption ability. Note that in a polarized film (in an embodiment in which optical film 1 is an optical film having ultraviolet absorption ability and optical film 2 is a polarizer), irradiation from the polarizer side may cause deterioration of the polarizer due to active energy rays. Therefore, the active energy ray-curable adhesive composition of the present invention is useful because it can be irradiated from the optical film side having ultraviolet absorption ability.

[0061] The method for applying the adhesive composition is appropriately selected depending on the viscosity of the composition and the desired thickness, and examples thereof include a reverse coater, a gravure coater (direct, reverse, or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, and a rod coater.

[0062] In the laminated optical film, any appropriate conditions may be adopted as the irradiation conditions of the active energy rays as long as the conditions are conditions under which the adhesive composition can be cured. For example, when ultraviolet rays or visible light are used as the active energy rays, the illuminance in the wavelength range of 395 to 445 nm is 200 to 2000 mW / cm ２ , the cumulative light amount is 100 to 1500 mJ / cm ２ That's about it.

[0063] From the viewpoint of productivity and adhesiveness, the thickness of the adhesive layer is preferably about 0.1 to 100 μm, more preferably about 0.3 to 10 μm, and even more preferably about 0.5 to 5 μm.

[0064] In the laminated optical film, the optical film 1 and the optical film 2 may be laminated via an intervening layer such as a surface modification layer, an easy-adhesive layer, a blocking layer, or a refractive index adjustment layer.

[0065] Examples of the surface modification treatment for forming the surface modification layer include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0066] Examples of the easy-adhesion adhesive that forms the easy-adhesion layer include forming materials containing various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based skeleton, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like.

[0067] The blocking layer is a layer having a function of preventing impurities such as oligomers and ions eluted from an optical film, etc., from migrating (penetrating) into an optical film such as a polarizer. The blocking layer may be any layer as long as it is transparent and can prevent impurities from eluting from an optical film, etc. Examples of materials for forming the blocking layer include urethane prepolymer-based forming materials, cyanoacrylate-based forming materials, and epoxy-based forming materials.

[0068] The refractive index adjusting layer is a layer provided to suppress a decrease in transmittance due to reflection between layers having different refractive indices in the optical film. Examples of the refractive index adjusting material for forming the refractive index adjusting layer include forming agents containing various resins such as silica-based, acrylic-based, acrylic-styrene-based, and melamine-based resins and additives.

[0069] An adhesive layer for bonding other members may be provided on one or both surfaces of the laminated optical film. A pressure-sensitive adhesive layer is suitable as the adhesive layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and can be appropriately selected and used from, for example, a pressure-sensitive adhesive having an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, or the like as a base polymer. In particular, a pressure-sensitive adhesive having excellent optical transparency, moderate wettability, cohesion, and adhesive properties, and excellent weather resistance, heat resistance, etc., such as a pressure-sensitive adhesive containing an acrylic polymer, is preferably used.

[0070] The application of the pressure-sensitive adhesive layer to one or both surfaces of the laminated optical film can be performed by any suitable method. Examples of application of the pressure-sensitive adhesive layer include preparing a pressure-sensitive adhesive solution and applying it directly to the laminated optical film by a suitable application method such as a casting method or a coating method, or forming a pressure-sensitive adhesive layer on a separator and transferring it onto the laminated optical film. The thickness of the pressure-sensitive adhesive layer can be determined appropriately depending on the intended use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. A laminated optical film having a pressure-sensitive adhesive layer provided on at least one surface thereof is also referred to as a pressure-sensitive adhesive layer-attached laminated optical film.

[0071] It is preferable that a separator be temporarily attached to cover the exposed surface of the pressure-sensitive adhesive layer to prevent contamination, etc., until the product is put into practical use. This prevents contamination, etc., of the pressure-sensitive adhesive layer under normal handling conditions. Examples of the separator include suitable thin sheets such as plastic films, rubber sheets, paper, cloth, nonwoven fabrics, nets, foam sheets, metal foils, and laminates thereof, which are coated with a suitable release agent, such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based release agent, as needed.

[0072] The laminated optical film can be used in various image display devices such as liquid crystal display devices and organic EL display devices.

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0074] Examples 1 to 5, Comparative Examples 1 to 8 Preparation of Adhesive Compositions In each of the Examples and Comparative Examples, the following components were mixed in the amounts shown in Table 1 at 25°C for 1 hour to prepare adhesive compositions (the units of the amounts shown in Table 1 are relative parts by mass). ACMO: N-acryloylmorpholine, manufactured by KJ Chemicals. DCP-A: dimethylol-tricyclodecane diacrylate, manufactured by Kyoeisha Chemical Co., Ltd. Omnirad 819: (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by IGM Resins. Omnirad 184: 1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by IGM Resins. Irgacure OXE01: 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)], manufactured by BASF. Omnirad 907: 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, manufactured by IGM Resins. DETX-S: "KAYACURE DETX-S", 2,4-diethylthioxanthone, manufactured by Nippon Kayaku Co., Ltd. UVS1331: "ANTHRACURE UVS-1331", 9,10-dibutoxyanthracene, manufactured by Air Water Performance Chemicals Inc. UVS2171: "ANTHRACURE UVS-2171", 1,4-diethoxynaphthalene, manufactured by Air Water Performance Chemicals Inc.

[0075] <Preparation of Optical Film with UV Absorption Ability> 81.98 parts by mass of isosorbide, 47.19 parts by mass of tricyclodecane dimethanol, 175.1 parts by mass of diphenyl carbonate, and 0.979 parts by mass of a 0.2% by mass aqueous solution of cesium carbonate as a catalyst were charged into a reaction vessel. In a nitrogen atmosphere, the heating bath temperature was heated to 150°C as the first step of the reaction, and the raw materials were dissolved (approximately 15 minutes) with stirring as necessary. Next, the pressure was increased from atmospheric pressure to 13.3 kPa, and the heating bath temperature was increased to 190°C over 1 hour, while the generated phenol was extracted from the reaction vessel. After the entire reaction vessel was held at 190°C for 15 minutes, the pressure inside the reaction vessel was increased to 6.67 kPa, and the heating bath temperature was increased to 230°C over 15 minutes as the second step, and the generated phenol was extracted from the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes. Furthermore, to remove the generated phenol, the pressure inside the reaction vessel was reduced to 0.200 kPa or less. After reaching the predetermined stirring torque, the reaction was terminated, and the resulting reaction product was extruded into water to obtain polycarbonate-based resin pellets. Subsequently, ADK STAB LA-F70 was added as a UV absorber to obtain polycarbonate-based resin pellets with UV absorption capabilities. The resulting UV-absorbed polycarbonate-based resin was vacuum-dried at 80°C for 5 hours, and then an optical film composed of the polycarbonate-based resin was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width: 300 mm, set temperature: 250°C), a chill roll (set temperature: 120-130°C), and a winder. The resulting optical film had a thickness of 20 μm.

[0076] <Preparation of Laminated Optical Film> The adhesive composition was applied to two optical films composed of the polycarbonate resin obtained above so that the total film thickness after curing would be 1.0 μm. For coating, an MCD coater (manufactured by Fuji Machine Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 1000 / inch, rotation speed: 140% / line speed) was used. Next, the optical films obtained above were bonded together via the adhesive-coated surfaces. Next, the obtained laminate was irradiated with ultraviolet light to cure the adhesive composition between the films, thereby obtaining a laminated optical film. A gallium lamp was used for ultraviolet irradiation, and the illuminance in the wavelength range of 395 to 445 nm was 300 mW / cm. ２ , the cumulative light amount is 500 mJ / cm ２ It was adjusted so that

[0077] <Evaluation of Adhesion> A sample film measuring 200 mm on a first side and 15 mm on a second side was cut out from the laminated optical film. The first side was the side extending parallel to the conveying direction during optical film formation. The second side was the side extending perpendicular to the conveying direction. Next, the optical film on the UV-irradiated surface of the sample film was bonded to a glass plate via a strong adhesive. Next, the 90° peel strength (N / 15 mm) of the optical film from the laminated optical film was measured using a Tensilon universal testing machine (product name "RTC", manufactured by A&D Co., Ltd.). In this measurement, the measurement temperature was 25°C, the peel angle was 90°, and the peel speed was 1000 mm / min. The results of each example and comparative example are shown in Table 1. The acceptable peel strength is 1.0 (N / 15 mm) or more, and 2.0 (N / 15 mm) or more is preferable.

[0078]

Claims

1. A laminated optical film in which an optical film 1, an adhesive layer, and an optical film 2 are laminated in this order, wherein the adhesive layer is formed from an active energy ray-curable adhesive composition containing an oxime ester-based photoinitiator, and at least one of the optical films 1 and 2 is an optical film having ultraviolet absorption ability.

2. The laminated optical film according to claim 1, wherein the optical film having ultraviolet absorption ability has a transmittance of 10% or less with respect to light of 380 nm.

3. The laminated optical film according to claim 1 or 2, wherein the active energy ray-curable adhesive composition contains a sensitizer.

4. The laminated optical film according to claim 3, wherein the sensitizer contains an anthracene-based sensitizer.

5. The laminated optical film according to claim 4, wherein the sensitizer contains a naphthalene-based sensitizer.

6. The laminated optical film according to claim 1 or 2, wherein the active energy ray adhesive composition contains a photoinitiator other than the oxime ester-based photoinitiator.

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