Laminated optical film

Abstract

To provide a laminated optical film excellent in adhesiveness of a polycarbonate resin including a structural unit derived from isosorbide.SOLUTION: A laminated optical film includes an optical film 1, an adhesive layer and an optical film 2 sequentially laminated. At least one of the optical films 1 and 2 is a polycarbonate resin film. The polycarbonate resin film includes a structural unit derived from a dihydroxy compound expressed by a formula (1). An HSP distance between an HSP of the polycarbonate resin film and an HSP of an adhesive composition composing the adhesive layer is 4.0 or less.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 been dyed (contains a dichroic substance such as iodine or a dichroic dye) and has both high transmittance and high polarization degree 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 it. Further, the polarizer is usually used as a polarizing film (polarizing plate) in which an optical film such as triacetyl cellulose is adhered to one or both sides thereof using an adhesive.

[0003] As such an optical film, in Patent Document 1, it is known to use a polycarbonate resin containing a structural unit derived from isosorbide from the viewpoints of excellent heat and humidity resistance, dimensional stability, and mechanical strength. Further, in Patent Document 2, specifically, an optical laminate using a retardation layer composed of the above polycarbonate resin film and bonded with an active energy ray-curable adhesive composition is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described optical laminate, when using an optical film of a polycarbonate resin containing a structural unit derived from isosorbide, there was room for improvement in the adhesiveness between the film and the active energy ray-curable adhesive composition.

[0006] In view of the above circumstances, an object of the present invention is to provide a laminated optical film excellent in adhesiveness of a polycarbonate resin containing a structural unit derived from isosorbide.

Means for Solving the Problems

[0007] That is, the present invention is a laminated optical film in which an optical film 1, an adhesive layer, and an optical film 2 are laminated in this order, and at least one of the optical films 1 and 2 is a polycarbonate resin film. The polycarbonate resin film has the formula (1):

Chemical formula

[0008] Further, in the laminated optical film of the present invention, the adhesive composition contains a monofunctional radically polymerizable compound and a radically polymerizable compound containing a polyfunctional radically polymerizable compound having two or more functional groups. In the radically polymerizable compound, the proportion of the monofunctional radically polymerizable compound is preferably 65% by mass or more, and the proportion of the polyfunctional radically polymerizable compound having two or more functional groups is preferably 35% by mass or less.

[0009] Further, in the laminated optical film of the present invention, the monofunctional radically polymerizable compound is preferably a (meth)acrylamide derivative containing a cyclic ether group.

[0010] In addition, in the laminated optical film of the present invention, it is preferable that the polyfunctional radical polymerizable compound having two or more functional groups is a bifunctional radical polymerizable compound having an alicyclic structure.

Advantages of the Invention

[0011] In the laminated optical film of the present invention, since the HSP distance between the HSP of the optical film of the polycarbonate resin containing the structural unit derived from isosorbide (including this optical isomer) and the HSP of the adhesive composition is equal to or less than a specific value, it is presumed that the components derived from the above polycarbonate resin can erode the adhesive layer, and thus the adhesiveness is excellent.

Embodiments for Carrying Out the Invention

[0012] 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, and at least one of the optical films 1 and 2 is a polycarbonate resin film.

[0013] <Polycarbonate Resin Film> The polycarbonate resin film has the formula (1):

Chemical Formula

[0014] The polycarbonate resin may further contain a structural unit derived from a dihydroxy compound other than the dihydroxy compound represented by the formula (1) (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 (1), it becomes possible to improve processability, heat resistance, impact resistance, etc.

[0015] Examples of other dihydroxy compounds include alicyclic dihydroxy compounds, aliphatic dihydroxy compounds, oxyalkylene glycols, aromatic dihydroxy compounds, and diols having a cyclic ether structure.

[0016] 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. By the alicyclic dihydroxy compound having a 5-membered ring or 6-membered ring structure, the heat resistance of the obtained polycarbonate can be increased. Examples of the alicyclic dihydroxy compound include cyclohexanedimethanols, tricyclodecanedimethanols, adamantanediols, pentacyclopentadecanedimethanols. From the viewpoints of easy availability and easy handling, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecanedimethanol are preferred.

[0017] 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 spiroglycols, dioxaneglycols, and the like.

[0018] The ratio of the dihydroxy compound represented by the formula (1) 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.

[0019] Among the above other dihydroxy compounds, when an alicyclic dihydroxy compound is used, the total ratio of the dihydroxy compound represented by the formula (1) 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.

[0020] In the laminated optical film, the HSP distance between the HSP of the polycarbonate resin film and the HSP of the adhesive composition forming the adhesive layer is 4.0 or less. The HSP distance (Ra-1 described later) between the HSP of the polycarbonate resin film and the HSP of the adhesive composition forming the adhesive layer is preferably 0.5 or more, more preferably 1 or more, from the viewpoint of adhesiveness, and preferably 10 or less, more preferably 5 or less, from the viewpoint of adhesiveness. The method for measuring the HSP of the polycarbonate resin film and the adhesive composition will be described later.

[0021] <Adhesive composition> The adhesive composition can be roughly classified into electron beam curable, ultraviolet curable, and visible light curable. 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, the active energy ray in the wavelength range of 10 nm to less than 380 nm is referred to as ultraviolet ray, and the active energy ray in the wavelength range of 380 nm to 800 nm is referred to as visible light.

[0022] <Radical polymerizable compound> The radical polymerizable compound used in the adhesive composition includes compounds having a radical polymerizable functional group of a carbon-carbon double bond 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.

[0023] <Monofunctional radical polymerizable compound> Examples of the monofunctional radical polymerizable compound include the formula (2):

Chemical formula

[0024] Specific examples of the compound represented by the above formula (2) 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, as the cyclic ether group-containing (meth)acrylamide derivative, a heterocyclic ring-containing (meth)acrylamide derivative in which the nitrogen atom of the (meth)acrylamide group forms a heterocyclic ring can be mentioned, for example, 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 polarizers. In particular, N-hydroxyethylacrylamide and N-acryloylmorpholine are preferable.

[0025] In addition to the above compounds, the adhesive composition may contain other monofunctional radical polymerizable compounds from the viewpoint of enabling the adhesive composition to exhibit various functions as a curable component. Examples of the other monofunctional radical polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, for example, (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, n-octadecyl (meth)acrylate, etc. can be mentioned.

[0026] 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-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In addition, as other monofunctional radically polymerizable compounds, radically polymerizable compounds having an active methylene group can be used. A 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.

[0031] From the perspective of achieving both adhesion to the optical film and optical durability in harsh environments, it is preferable to use a monofunctional radically polymerizable compound and a polyfunctional radically polymerizable compound in combination. Since the monofunctional radically 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 radically polymerizable compound can three-dimensionally crosslink the cured product of the adhesive composition, it is preferably included in the adhesive composition.

[0032] <Polyfunctional radically polymerizable compounds having two or more functional groups> 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, dimethyloltricyclodecane diacrylate, dimethyloldicyclopentane 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. can be mentioned. Among these, from the viewpoint of affinity with the adherend, bifunctional radically polymerizable compounds having an alicyclic structure such as dimethyloltricyclodecane diacrylate and dimethyloldicyclopentane diacrylate are preferable.

[0033] When the monofunctional radically polymerizable compound and the polyfunctional radically polymerizable compound are used in combination, in the radically polymerizable compound, the proportion of the monofunctional radically polymerizable compound is preferably 65% by mass or more, more preferably 70% by mass or more, still more preferably 75% by mass or more, and from the viewpoint of adhesion strength, it is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less. Further, in this case, from the viewpoint of adhesion strength, the proportion of the polyfunctional radically polymerizable compound in the radically polymerizable compound is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less.

[0034] Further, when the compound represented by the above formula (2) is used as the monofunctional radically polymerizable compound, in the radically polymerizable compound, the proportion of the compound of the above formula (2) is preferably 65% by mass or more, more preferably 70% by mass or more, still more preferably 75% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or more, still more preferably 85% by mass or less.

[0035] When the above other monofunctional radically polymerizable compound is used as the monofunctional radically polymerizable compound, the proportion of the other monofunctional radically polymerizable compound in the radically polymerizable compound is usually about 30% by mass or less.

[0036] When ultraviolet rays or visible light is used as the active energy ray for the adhesive composition, it preferably contains a photoinitiator.

[0037] <Photoinitiator> The photoinitiator is appropriately selected by active energy rays. When curing with ultraviolet rays or visible light, a photoinitiator that undergoes ultraviolet ray or visible light cleavage is used. Examples of the photoinitiator include benzophenone-based compounds such as benzyl, benzophenone, benzoylbenzoic 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-hydroxycyclohexylphenylketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropan-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 benzyldimethylketal; 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.

[0038] Further, when the optical film 1 or 2 used for laminating the adhesive composition has difficulty transmitting light of 380 nm or less, the adhesive composition is preferably used as being visible light curable. In this case, the photoinitiator has the formula (3):

Chemical formula

Chemical formula

[0039] Examples of the photoinitiator highly sensitive to light of 380 nm or more include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, and the like.

[0040] In addition, examples of the photopolymerization initiator include oxime ester-based photopolymerization initiators such as compounds described in JP-A-2000-80068, JP-A-2001-233842, WO2010 / 527339, WO2010 / 527338, JP-A-2013-041153, WO2015 / 036910, etc. Specific compounds include, for example, 1,2-octanedione, 1-4-(phenylthio)-2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-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.

[0041] The blending amount of the photopolymerization initiator may be set as appropriate. For example, it is usually 20 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound. The blending amount of the photopolymerization initiator is preferably 1 to 15 parts by mass, more preferably 3 to 10 parts by mass, with respect to 100 parts by mass of the radically polymerizable compound.

[0042] In addition, 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, isoamyl 4-dimethylaminobenzoate, etc. When using a 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.

[0043] In addition, when a radical polymerizable compound having an active methylene group is used 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 adhesiveness of the adhesive layer of the polarizing film is remarkably improved especially in a high humidity environment or immediately after taken out from water (non-dried state). Examples of the radical polymerization initiator having the 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. Examples of the thioxanthone-based radical polymerization initiator include the compound represented by the above formula (3).

[0044] In the adhesive composition, various additives can be blended as other optional components within a range not impairing the objects 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, and cellulose resin; oligomers such as acrylic oligomer, fluorine oligomer, silicone oligomer, and polysulfide oligomer; sensitizer, 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.

[0045] <Laminated optical film> The laminated optical film of the present invention is formed by laminating an optical film 1, an adhesive layer formed from the adhesive composition, and an optical film 2 in this order, and at least one of the optical films 1 and 2 is the polycarbonate resin film. 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".

[0046] The optical film may be an optical film having an ultraviolet absorption ability from the viewpoint of protecting polarizers, liquid crystals, etc. from ultraviolet rays when the laminated optical film is incorporated into various image display devices. In this case, the transmittance with respect to light of 380 nm is preferably 20% or less, 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 surface of the optical film.

[0047] Examples of the ultraviolet absorber include conventionally known oxybenzophenone-based compounds, benzotriazole-based compounds, salicylic acid ester-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, triazine-based 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.

[0048] The optical film 1 or 2 that is not the polycarbonate resin film is 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. Examples of the thermoplastic resin 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 copolymer, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins) having a cyclic or norbornene structure, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. Further, for the transparent protective film, a cured layer formed from a thermosetting resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, silicone, etc. or an ultraviolet curable resin can be used. 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 suitable additives such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, antistatic agents, pigments, colorants, etc.

[0049] The thickness of the optical film can be appropriately determined, but 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.

[0050] When using the laminated optical film as a polarizing film, it is preferable that the optical film 1 is the above-mentioned polycarbonate resin film and the optical film 2 is a polarizer. As the polarizer, a known polarizer formed by adsorbing and aligning a dichroic substance such as iodine or a dichroic dye on a polyvinyl alcohol-based film can be applied.

[0051] 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.

[0052] 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 used by laminating it on a transparent protective film having no retardation.

[0053] In the polarizing film, a functional layer such as a hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer, or an antiglare layer can be provided on the surface of the transparent protective film where the polarizer is not laminated. The 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.

[0054] In the laminated optical film, the adhesive composition is directly applied to the optical film 1 and / or the optical film 2. 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 irradiated from any appropriate direction. However, since the adhesive composition has excellent adhesiveness even when used for laminating an optical film 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 the polycarbonate resin film 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, since the adhesive composition can be irradiated from the side of the optical film having ultraviolet absorption ability, it is useful.

[0055] As a method for applying the adhesive composition, it is appropriately selected according to the viscosity of the composition and the desired 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.

[0056] 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 about 100 to 1500 mJ / cm 2 .

[0057] 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.

[0058] 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.

[0059] Examples of the surface modification treatment for forming the surface modification layer include corona treatment, plasma treatment, primer treatment, saponification treatment, and the like.

[0060] 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, and the like.

[0061] 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, and the like.

[0062] The refractive index adjustment layer is a layer provided to suppress a decrease in transmittance due to reflection between layers having different refractive indexes 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, and the like.

[0063] 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 having excellent 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.

[0064] 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. As the attachment of the pressure-sensitive adhesive layer, for example, a pressure-sensitive adhesive solution is prepared and directly attached onto the laminated optical film by an appropriate spreading method such as a casting method or a coating method, or a pressure-sensitive adhesive layer is formed on a separator and transferred 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.

[0065] 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 until it is put into practical use. Thereby, contamination of the pressure-sensitive adhesive layer can be prevented in the usual handling state. As the separator, for example, an appropriate thin sheet such as a plastic film, a rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet, metal foil, or a laminate thereof is used, which is 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.

[0066] The laminated optical film can be used in various image display devices such as liquid crystal display devices and organic EL display devices.

Examples

[0067] Examples are given below to explain the present invention in more detail, but the present invention is not limited to only these examples.

[0068] <Examples 1-6, Comparative Example 1> <Preparation of Adhesive Composition> In each example and comparative example, the following components were mixed at 25°C for 1 hour in the blending amounts shown in Table 1 to prepare an adhesive composition (the unit of the blending amounts shown in Table 1 is relative "parts by mass"). ACMO: N-acryloylmorpholine, manufactured by KJ Chemicals DCP-A: "Light Acrylate DCP-A", dimethyloltricyclodecane diacrylate, manufactured by Kyoeisha Chemical Co., Ltd. DPHA: dipentaerythritol hexaacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. M220: "Aronix M220", tripropylene glycol diacrylate, manufactured by Toagosei Co., Ltd. 9EGA: "Light Acrylate 9EG-A", PEG#400 diacrylate, manufactured by Kyoeisha Chemical 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.

[0069] <Preparation of Polycarbonate-based Resin Film> 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 (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.

[0070] <Preparation of laminated optical film> An adhesive composition was coated on 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 coating, 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 laminated 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 1000 mW / cm 2 , and the integrated light quantity was adjusted to be 600 mJ / cm 2 .

[0071] <Evaluation of Adhesion> A sample film with a size of 200 mm for the first side × 15 mm for the second side 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 a direction perpendicular 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 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 peel strength of 1.0 (N / 15 mm) or more is taken as the passing standard, and preferably 1.5 (N / 15 mm) or more.

[0072] <Method for Calculating the HSP of the Adhesive Composition> The HSP of the adhesive composition was determined by calculating the Hansen solubility parameter (HSP) for each constituent material of the composition by the Y-MB method of Hansen Solubility Parameter in Practice (HSPiP) and taking the average value according to the molar ratio in the composition.

[0073] <Calculation Method of HSP of Polycarbonate Resin Film> The polycarbonate resin film was immersed in 9 solvents with different solubilities, namely acetone, ethyl acetate, trichlorobenzene, propylene carbonate, γ-butyrolactone, methyl ethyl ketone, diacetone alcohol, hexane, methanol, and their mixed solvents for 24 hours. The state of the transparent protective film after 24-hour immersion was classified into three stages: (1) dissolution, (2) swelling, and (3) insoluble. Based on the solubility information in each solvent thus obtained, the Hansen solubility parameter (HSP) was calculated using Hansen Solubility Parameter in Practice (HSPiP) ver.5.4.04 (http: / / www.hansen-solubility.com / index.php).

[0074] <Calculation Method of HSP Distance> When the dispersion term of the Hansen solubility parameter of the polycarbonate resin film is σd, the polar term is σp, the hydrogen bond term is σh, and the dispersion term of the Hansen solubility parameter of the adhesive composition is σAd, the polar term is σAp, and the hydrogen bond term is σAh, the following formula; Ra-1 = [4×(σd - σAd) 2 +2×(σp - σAp) 2 +2×(σh - σAh) 2 1 / 2 was defined as the "HSP distance between the HSP of the polycarbonate resin film and the HSP of the adhesive composition" (= Ra-1). It was calculated using the Hansen solubility parameters of the polycarbonate resin film and the adhesive composition calculated by the above method. The values of each example and comparative example are shown in Table 1.

[0075]

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 at least one of the optical films 1 and 2 is a polycarbonate-based resin film, the polycarbonate-based resin film contains a structural unit derived from a dihydroxy compound represented by the formula (1): 【Chemical 1】 and the HSP distance between the HSP of the polycarbonate-based resin film and the HSP of the adhesive composition forming the adhesive layer is 4.0 or less. A laminated optical film characterized by this.

2. The adhesive composition contains a monofunctional radically polymerizable compound and a radically polymerizable compound containing a polyfunctional radically polymerizable compound having two or more functional groups, and in the radically polymerizable compound, the proportion of the monofunctional radically polymerizable compound is 65% by mass or more, and the proportion of the polyfunctional radically polymerizable compound having two or more functional groups is 35% by mass or less. The laminated optical film according to Claim 1, characterized by this.

3. The monofunctional radically polymerizable compound is a (meth)acrylamide derivative containing a cyclic ether group. The laminated optical film according to Claim 2, characterized by this.

4. The polyfunctional radically polymerizable compound having two or more functional groups is a bifunctional radically polymerizable compound having an alicyclic structure. The laminated optical film according to Claim 2 or 3, characterized by this. ​

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