Laminated optical film

Abstract

To provide a laminated optical film excellent in adhesiveness even when bonding an optical film having ultraviolet absorptivity.SOLUTION: A laminated optical film includes an optical film 1, an adhesive layer and an optical film 2 sequentially laminated. The adhesive layer is composed of an active energy ray-curable adhesive composition including an oxime ester-based photoinitiator. At least one of the optical films 1 and 2 is an optical film having ultraviolet absorptivity.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, as a polarizer used in various image display devices such as liquid crystal display devices and organic EL display devices, a polyvinyl alcohol-based film that has both high transmittance and high polarization degree and is dyed (contains a dichroic substance such as iodine or a dichroic dye) has been used. The polarizer is manufactured by subjecting a polyvinyl alcohol-based film to various treatments such as dyeing, crosslinking, and stretching in a bath (treatment bath) and then drying. Also, a polarizer is usually used as a polarizing film (polarizing plate) in which an optical film such as triacetyl cellulose is bonded to one or both sides thereof using an adhesive.

[0003] As an adhesive for an optical film, an aqueous adhesive composition and an active energy ray-curable adhesive composition are widely known. Also, in the above-described optical film, an optical film having ultraviolet absorption ability may be used. In such a case, Patent Document 1 discloses that a drying and curing type adhesive such as an aqueous adhesive is suitable because a sufficient amount of ultraviolet rays for curing the adhesive is absorbed by the optical film having ultraviolet absorption ability.

[0004] Also, Patent Document 2 describes that from the viewpoint of productivity that the drying process of the adhesive composition can be eliminated, an active energy ray-curable adhesive composition is more preferable than an aqueous adhesive composition. Further, in the above-described case, it has been proposed to use a visible light-curable adhesive composition containing a photoinitiator highly sensitive to light of 380 nm or more.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, from the viewpoint of adhesiveness, an active energy ray-curable adhesive composition for an optical film different from the above composition has been desired.

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

Means for Solving the Problems

[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, and 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.

[0009] Further, in the laminated optical film of the present invention, it is preferable that the optical film having ultraviolet absorption ability has a transmittance of 10% or less with respect to light of 380 nm.

[0010] Further, in the laminated optical film of the present invention, it is preferable that the active energy ray-curable adhesive composition contains a sensitizer.

[0011] Further, in the laminated optical film of the present invention, it is preferable that the sensitizer contains an anthracene-based sensitizer.

[0012] Further, in the laminated optical film of the present invention, it is preferable that the sensitizer contains a naphthalene-based sensitizer.

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

Advantages of the Invention

[0014] Unlike the conventional adhesive layer, the adhesive layer of the laminated optical film of the present invention is formed from an active energy ray-curable adhesive composition containing an oxime ester-based photopolymerization initiator. Therefore, it has high sensitivity to active energy rays and is an adhesive that generates highly reactive radical species. Thus, even when an optical film having ultraviolet absorption ability is laminated, it exhibits excellent adhesiveness.

Embodiments for Carrying Out the Invention

[0015] In the laminated optical film of the present invention, an optical film 1, an adhesive layer, and an optical film 2 are laminated in this order. The adhesive layer is 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 is an optical film having ultraviolet absorption 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 composition can be broadly classified into electron beam curability, ultraviolet curability, and visible light curability. Further, as the form of curing, it can be classified into a radical polymerizable curable adhesive composition and a cationic polymerizable adhesive composition. In the present invention, active energy rays in the wavelength range of 10 nm to less than 380 nm are referred to as ultraviolet rays, and active energy rays in the wavelength range of 380 nm to 800 nm are referred to as visible light. From the viewpoint of laminating an optical film having ultraviolet absorption ability, the active energy ray-curable adhesive composition that can be used in the present invention is preferably visible light curable using active energy rays having a wavelength of 380 nm or more.

[0018] <Oxim ester-based photoinitiator> The oxim ester-based photoinitiator has an oxim ester skeleton in the molecule and, from the viewpoint of laminating an optical film having ultraviolet absorption ability, may be any that can absorb active energy rays with a wavelength of 380 nm or more and generate radicals. For example, compounds described in JP-A-2000-80068, JP-A-2001-233842, JP-T-2010-527339, JP-T-2010-527338, JP-A-2013-041153, WO 2015 / 036910, etc. can be mentioned. Specific compounds include, for example, 1,2-octanedione, 1-4-(phenylthio)-2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), etc. Commercially available products include, as compounds having a carbazole skeleton, Irgacure OXE-02 (manufactured by BASF), Adeka Arcles NCI-831 (manufactured by ADEKA), N-1919 (manufactured by ADEKA), TR-PBG-304 (manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd.); as compounds having a diphenyl sulfide skeleton, Irgacure OXE-01 (manufactured by BASF), Adeka Arcles NCI-930 (manufactured by ADEKA), TR-PBG-345 (manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd.), TR-PBG-3057 (manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd.); as compounds having a fluorene skeleton, TR-PBG-365 (manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd.), etc. The oxim ester-based photoinitiator can be used alone or in combination of two or more.

[0019] The blending amount of the oxim ester-based photoinitiator may be set as appropriate. From the viewpoint of the 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 with respect to 100 parts by mass of the radical polymerizable compound described later. 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 with respect to 100 parts by mass of the radical polymerizable compound described later.

[0020] The active energy ray-curable adhesive composition may contain a photoinitiator other than the oxime ester-based photoinitiator. Examples of such photoinitiators include benzophenone-based compounds such as benzyl, benzophenone, benzoyl benzoic acid, 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, α-hydroxycyclohexyl phenyl ketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin alkyl ether-based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether; aromatic ketal-based compounds such as benzyldimethyl ketal; aromatic sulfonyl chloride-based compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime-based compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone-based compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphine oxides; acylphosphonates and the like. The photoinitiator other than the oxime ester-based photoinitiator can be used alone or in combination of two or more.

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

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

[0023] <Sensitizer> The sensitizer may be any one that can generate radicals from the oxime ester-based photopolymerization initiator by transferring the energy obtained by absorbing light to the oxime ester-based photopolymerization initiator. For example, anthracene-based sensitizers, naphthalene-based sensitizers, benzoflavin-based sensitizers, perylene-based sensitizers, thioxanthone-based sensitizers, etc. can be mentioned. The sensitizer can be used alone or in combination of two or more.

[0024] From the viewpoint of laminating an optical film having ultraviolet absorption ability, a sensitizer capable of absorbing active energy rays having a wavelength of 380 nm or more is preferable. In particular, from the viewpoint of photosensitivity, the anthracene-based sensitizer is preferable. As commercially available products, for example, Antracure UVS-1331 (manufactured by Air Water Performance Chemicals), Antracure UVS-581 (manufactured by Air Water Performance Chemicals), etc. can be mentioned.

[0025] In addition, from the viewpoint of improving the energy conversion efficiency of the anthracene-based sensitizer that has absorbed light, it is preferable to contain a naphthalene-based sensitizer. As commercially available products, for example, Antracure UVS-2171 (manufactured by Air Water Performance Chemicals), etc. can be mentioned.

[0026] The blending amount of the sensitizer may be set as appropriate. From the viewpoint of photosensitivity, it is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and further preferably 100 parts by mass or more with respect to 100 parts by mass of the oxime ester-based photopolymerization initiator. From the viewpoint of solubility, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and further preferably 150 parts by mass or less with respect to 100 parts by mass of the oxime ester-based photopolymerization initiator.

[0027] Also, 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> Examples of the radical polymerizable compound used in the adhesive composition include compounds having a radical polymerizable functional group such as a (meth)acryloyl group or a vinyl group. As these curable components, either a monofunctional radical polymerizable compound or a polyfunctional radical polymerizable compound having two or more functional groups can be used. Further, these radical polymerizable compounds can be used alone or in combination of two or more. As these radical polymerizable compounds, for example, compounds having a (meth)acryloyl group are suitable. In the present invention, (meth)acryloyl means 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 the following formula (1): [Chemical formula] (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 heterocyclic ring.) Compounds represented by the formula are exemplified. The carbon number of the alkyl moiety of the alkyl group, hydroxyalkyl group, and / or alkoxyalkyl group is not particularly limited, but for example, those having 1 to 4 carbon atoms are exemplified. Also, R 2 and R3 Examples of the cyclic heterocyclic ring that may be formed include N-acryloylmorpholine.

[0030] Specific examples of the compound represented by the above formula (1) include, for example, 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, N-hexyl(meth)acrylamide; N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-methylol-N-propane(meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide, N-ethoxymethylacrylamide, etc. Further, examples of the cyclic ether group-containing (meth)acrylamide derivative include heterocyclic ring-containing (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocyclic ring, such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, etc. Among these, cyclic ether group-containing (meth)acrylamide derivatives are preferable from the viewpoints of excellent reactivity, obtaining a cured product with a high elastic modulus, and excellent adhesion to a polarizer. Particularly, N-hydroxyethylacrylamide and N-acryloylmorpholine are preferable.

[0031] Also, when using the compound represented by the above formula (1), in the radical polymerizable compound, the proportion of the above formula (1) is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, from the viewpoint of affinity with the adherend, and preferably 95% by mass or less, more preferably 90% by mass or less, further 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 radical polymerizable compounds from the viewpoint of enabling various functions to be expressed in the adhesive composition as curable components. Examples of other monofunctional radical polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, for example, (meth)acrylic acid (C1-C20) 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, n-octadecyl (meth)acrylate, etc. can be mentioned.

[0033] Examples of the (meth)acrylic acid derivative include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; polycyclic (meth)acrylates such as 2-isobornyl (meth)acrylate, 2-norbornyl methyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornyl methyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and alkoxy group- or phenoxy group-containing (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 derivative 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; 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; halogen-containing (meth)acrylates such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; oxetane group-containing (meth)acrylates such as 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; (meth)acrylates having a heterocyclic ring such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; and hydroxy pivalic acid neopentyl glycol (meth)acrylic acid adduct, p-phenylphenol (meth)acrylate, and the like.

[0035] In addition, examples of 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] In addition, examples of other monofunctional radically polymerizable compounds include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinyl-based monomers having a nitrogen-containing heterocyclic ring such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

[0037] In addition, as other monofunctional radically polymerizable compounds, radically polymerizable compounds having an active methylene group can be used. The radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acrylic group at the terminal or in the molecule and having an active methylene group. Examples of the active methylene group include an acetoacetyl group, an alkoxymalonyl group, or 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-ethoxymalonyl-oxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, N-(2-acetoacetylaminoethyl)acrylamide, and the like.

[0038] When using the above-mentioned other monofunctional radically polymerizable compound, in the radically polymerizable compound, the proportion of the other monofunctional radically polymerizable compound is usually about 30% by mass or less.

[0039] <Bifunctional or higher polyfunctional radically polymerizable compound> Examples of the bifunctional or higher 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 di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane diacrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, esterified products of (meth)acrylic acid and polyhydric alcohols such as EO-modified diglycerin tetra(meth)acrylate, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. 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), CD-536 (manufactured by Sartomer), etc. Also, if necessary, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and various (meth)acrylate-based monomers, etc. may be included.

[0040] From the perspective of achieving both adhesion to the optical film and optical durability in harsh environments, it is preferable to use a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound in combination. Since the monofunctional radical polymerizable compound has a relatively low liquid viscosity, the liquid viscosity of the adhesive composition can be reduced by including it in the adhesive composition. Also, since the polyfunctional radical polymerizable compound can three-dimensionally crosslink the cured product of the adhesive composition, it is preferably included in the adhesive composition. When using the polyfunctional radical polymerizable compound, the proportion of the polyfunctional radical polymerizable compound in the radical 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] Also, a polymerization initiation aid may be added as needed. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and the like. When using the polymerization initiation aid, the addition amount is usually about 5 parts by mass or less with respect to 100 parts by mass of the adhesive composition.

[0042] Also, when using a radical polymerizable compound having an active methylene group as the radical polymerizable compound, it is preferably used in combination with a radical polymerization initiator having a hydrogen abstraction action. According to such a configuration, the adhesion of the adhesive layer of the polarizing film is significantly improved, especially in a high humidity environment or immediately after being taken out of water (non-dried state). Examples of the radical polymerization initiator having a hydrogen abstraction action 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 can be blended with various additives as other optional components within a range not impairing the object and effects of the present invention. Examples of such additives include polymers such as chlorinated polyolefin, epoxy resin, polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene block copolymer, petroleum resin, xylene resin, ketone resin, cellulose resin, etc.; oligomers such as acrylic oligomer, fluorine-based oligomer, silicone-based oligomer, polysulfide-based oligomer, etc.; photoacid generator, photobase generator, silane coupling agent, polyrotaxane, organometallic compound, polymerization inhibitor, antifoaming agent, surfactant, plasticizer, ultraviolet absorber, inorganic filler, pigment, dye, and the like.

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

[0045] From the viewpoint of being able to protect a polarizer, liquid crystal, etc. from ultraviolet rays when the laminated optical film is incorporated into various image display devices, the optical film having the ultraviolet absorption ability preferably has a transmittance of 20% or less with respect to light of 380 nm, and more preferably 10% or less. To impart ultraviolet absorption ability to the optical film, for example, the material constituting the optical film may have ultraviolet absorption 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 optical film surface.

[0046] Examples of the ultraviolet absorber include conventionally known oxybenzone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, triazine compounds, etc. Examples of commercially available products include Adeka Stab LA-46 (manufactured by ADEKA), Adeka Stab LA-F70 (manufactured by ADEKA), KemiSorb 102 (manufactured by Chemipro Kasei Co., Ltd.), Chiguard 5405 (manufactured by Chitec technology), Tinuvin 405 (manufactured by BASF), Tinuvin 460 (manufactured by BASF), Tinuvin 479 (manufactured by BASF), Tinuvin 1600 (manufactured by BASF), etc.

[0047] The optical films 1 and 2 are not particularly limited, and for example, various transparent protective films used in various image display devices can be used. As the material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. is used. As the thermoplastic resin, for example, 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 polyamides, polyimide resins, polyethylene, polypropylene, polyolefin resins such as ethylene-propylene copolymers, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins) having a cyclic or norbornene structure, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof can be mentioned. Further, the transparent protective film can use a cured layer formed from a thermosetting resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, silicone, etc. or an ultraviolet curable resin. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferable. The transparent protective film may contain any appropriate additives such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, antistatic agents, pigments, colorants, etc.

[0048] Further, the polycarbonate resin is usually produced by reacting a dihydroxy compound having at least one bonding structure -CH2-O- in the molecule with a carbonic acid diester in the presence of a polymerization catalyst. From the viewpoint that the polycarbonate resin can be produced from carbohydrates using bio-originated substances as raw materials, formula (2):

Chemical formula

[0049] The polycarbonate resin may further contain a structural unit derived from a dihydroxy compound other than the dihydroxy compound represented by the formula (2) (hereinafter, also simply referred to as "other dihydroxy compound"). By further containing a structural unit derived from a dihydroxy compound other than the dihydroxy compound represented by the formula (2), it becomes possible to improve processability, 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 compounds containing a 5-membered ring structure or a 6-membered ring structure are preferred. Further, the 6-membered ring structure may be fixed in a chair form or a boat form by a covalent bond. Since the alicyclic dihydroxy compound has a 5-membered or 6-membered ring structure, the heat resistance of the resulting polycarbonate can be increased. Examples of the alicyclic dihydroxy compound include cyclohexanedimethanols, tricyclodecanedimethanols, adamantanediols, and pentacyclopentadecanedimethanols. From the viewpoints of easy availability and easy handling, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecanedimethanol are preferred.

[0052] Examples of the aliphatic dihydroxy compound 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, polyethylene glycol, and the like. Examples of the aromatic dihydroxy compound 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, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, and the like. Examples of the diols having a cyclic ether structure include spiro glycols and dioxane glycols.

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

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

[0055] The thickness of the transparent protective film can be determined as appropriate. Generally, from the viewpoints of workability such as strength and handleability, and thin layer properties, 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 using the laminated optical film as a polarizing film, the optical film 1 is an optical film having the above-mentioned ultraviolet absorption ability, and the optical film 2 is preferably a polarizer. As the polarizer, a known polarizer formed by adsorbing and orienting a dichroic substance such as iodine or a dichroic dye on a polyvinyl alcohol-based film can be applied.

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

[0058] Examples of the retardation plate include a birefringent film formed by uniaxially or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and a film supporting an alignment layer of a liquid crystal polymer. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. In addition, the retardation plate may be attached to a transparent protective film having no retardation and used.

[0059] In the polarizing film, functional layers such as a hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer, and an antiglare layer can be provided on the surface of the transparent protective film where the polarizer is not laminated. Note that the above-mentioned functional layers such as the hard coat layer, the antireflection layer, the anti-sticking layer, the diffusion layer, and the antiglare layer can be provided on the protective film itself, or can be provided separately as a separate body from the protective film.

[0060] In the laminated optical film, the active energy ray curable adhesive composition is directly applied to the optical film 1 and / or the optical film 2, and after laminating the optical film 1 and the optical film 2, active energy rays (electron beams, ultraviolet rays, visible light, etc.) are irradiated to cure the adhesive composition to form an adhesive layer. The irradiation direction of the active energy rays can be from any appropriate direction. However, since the active energy ray curable adhesive composition of the present invention has excellent adhesiveness even when used for laminating optical films having ultraviolet absorption ability, it may be irradiated from the side of the optical film having ultraviolet absorption ability. In the case of a polarizing film (a mode in which the optical film 1 is an optical film having ultraviolet absorption ability and the optical film 2 is a polarizer), if irradiated from the polarizer side, the polarizer may be deteriorated by the active energy rays. Therefore, the active energy ray curable adhesive composition of the present invention can be irradiated from the side of the optical film having ultraviolet absorption ability, which is useful.

[0061] As a method for applying the adhesive composition, it is appropriately selected according to the viscosity of the composition and the target thickness. For example, a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, etc. can be mentioned.

[0062] In the laminated optical film, the irradiation conditions of the active energy rays may be any appropriate conditions as long as they can cure the adhesive composition. For example, when ultraviolet rays or visible light is used as the active energy rays, the illuminance in the wavelength range of 395 to 445 nm is 200 to 2000 mW / cm 2 , and the integrated light quantity is 100 to 1500 mJ / cm 2 or so.

[0063] From the viewpoints 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, between the optical film 1 and the optical film 2, it may be laminated via an intervening layer such as a surface modification treatment layer, an easy adhesive layer, a block 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, saponification treatment, etc.

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

[0067] The block layer is a layer having a function of preventing impurities such as oligomers and ions eluted from an optical film or the like from migrating (invading) into an optical film such as a polarizer. The block layer may be a layer having transparency and capable of preventing impurities eluted from an optical film or the like. Examples of the material for forming the block layer include urethane prepolymer-based forming materials, cyanoacrylate-based forming materials, epoxy-based forming materials, etc.

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

[0069] An adhesive layer for bonding other members may be provided on one or both surfaces of the laminated optical film. As the adhesive layer, a pressure-sensitive adhesive layer is preferable. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, those based on polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based or rubber-based polymers can be appropriately selected and used. In particular, those excellent in optical transparency, showing appropriate wettability, cohesiveness, and adhesiveness, and excellent in weather resistance, heat resistance, etc., such as pressure-sensitive adhesives containing acrylic polymers, are preferably used.

[0070] The attachment of the pressure-sensitive adhesive layer to one or both sides of the laminated optical film can be carried out by an appropriate method. Examples of the attachment of the pressure-sensitive adhesive layer include a method of preparing a pressure-sensitive adhesive solution and directly attaching it onto the laminated optical film by an appropriate spreading method such as a casting method or a coating method, or a method of 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 appropriately determined according to the purpose of use, adhesive strength, etc. Generally, it is 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. Thus, the one having a pressure-sensitive adhesive layer provided on at least one surface of the laminated optical film is also referred to as a laminated optical film with a pressure-sensitive adhesive layer.

[0071] It is preferable that a separator is temporarily attached and covered to the exposed surface of the pressure-sensitive adhesive layer for the purpose of preventing contamination, etc., until it is put into practical use. Thereby, contamination of the pressure-sensitive adhesive layer can be prevented in a general handling state. Examples of the separator include appropriate thin sheets such as plastic films, rubber sheets, papers, cloths, non-woven fabrics, nets, foamed sheets, metal foils, and laminates thereof, which are coated with an appropriate release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based release agent as required.

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

Examples

[0073] Examples are given below to explain the present invention in more detail, but the present invention is not limited to only these examples.

[0074] <Examples 1-5, Comparative Examples 1-8> <Preparation of Adhesive Composition> In each of the examples and comparative examples, the following components were mixed at the compounding amounts shown in Table 1 at 25°C for 1 hour to prepare an adhesive composition (the unit of the compounding amounts shown in Table 1 is 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 UVS2171: "ANTHRACURE UVS-2171", 1,4-Diethoxynaphthalene, manufactured by Air Water Performance Chemicals

[0075] <Preparation of Optical Film Having Ultraviolet Absorbing Ability> To 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 mass% aqueous solution of cesium carbonate as a catalyst were charged into a reaction vessel. As the first stage of the reaction under a nitrogen atmosphere, the temperature of the heating bath was heated to 150°C, and the raw materials were dissolved (for about 15 minutes) while stirring as necessary. Next, the pressure was changed from normal pressure to 13.3 kPa, and while raising the temperature of the heating bath to 190°C over 1 hour, the generated phenol was withdrawn outside the reaction vessel. After maintaining the entire reaction vessel at 190°C for 15 minutes, as the second stage of the reaction, the pressure inside the reaction vessel was set to 6.67 kPa, and the temperature of the heating bath was raised to 230°C in 15 minutes, and the generated phenol was withdrawn outside the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and in order to further remove the generated phenol, the pressure inside the reaction vessel was made to reach 0.200 kPa or less. After reaching a predetermined stirring torque, the reaction was terminated, and the generated reaction product was extruded into water to obtain pellets of a polycarbonate-based resin. Subsequently, Adeka Stab LA-F70 was kneaded as an ultraviolet absorber to obtain pellets of a polycarbonate-based resin having ultraviolet absorption ability. After vacuum drying the obtained polycarbonate-based resin having ultraviolet absorption ability at 80°C for 5 hours, an optical film composed of a polycarbonate-based resin was produced using a film forming apparatus 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 thickness of the obtained optical film was 20 μm.

[0076] <Preparation of laminated optical film> An adhesive composition was applied onto two optical films made of the polycarbonate resin obtained above so that the total film thickness after curing would be 1.0 μm. For the application, an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count 1000 lines / inch, rotation speed 140% / pair line speed) was used. Next, the optical films obtained above were bonded together through the surface coated with the adhesive. Next, the obtained laminate was irradiated with ultraviolet rays to cure the adhesive composition between the films, thereby obtaining a laminated optical film. A gallium lamp was used for the ultraviolet irradiation, and the illuminance in the wavelength range of 395 to 445 nm was adjusted to be 300 mW / cm 2 , and the integrated light quantity was adjusted to be 500 mJ / cm 2 .

[0077] <Adhesion evaluation> A sample film with a size of the first side 200 mm × the second side 15 mm was cut out from the laminated optical film. The first side is the side extending parallel to the conveyance direction during the formation of the optical film. The second side is the side extending in the direction orthogonal to the conveyance direction. Next, the optical film on the ultraviolet irradiation surface of the sample film was bonded to a glass plate through 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 Company). In this measurement, the measurement temperature was set to 25°C, the peel angle was set to 90°, and the peel speed was set to 1000 mm / min. The results of each example and comparative example are shown in Table 1. The pass criterion for the peel strength is 1.0 (N / 15 mm) or more, and preferably 2.0 (N / 15 mm) or more.

[0078]

Table 1

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 an ultraviolet absorption ability. The laminated optical film is characterized by this.

2. The laminated optical film according to claim 1, wherein the optical film having an 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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