Stacked optical films and image display devices

Abstract

To provide a laminated optical film that suppresses interference unevenness and has excellent visibility, and an image display device equipped with the laminated optical film. [Solution] A laminated optical film comprising a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film, laminated in this order, wherein the first adhesive layer and the second adhesive layer are cured layers of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. Preferably, the refractive index of both the first adhesive layer and the second adhesive layer is 1.55 or higher. Preferably, the refractive index of both the first optical film and the second optical film is 1.55 or higher. Preferably, both the first optical film and the second optical film are liquid crystal phase difference films, and preferably the third optical film is a polarizing film equipped with at least a polarizer.

Description

[Technical Field]

[0001] The present invention relates to a laminated optical film and an image display device. The laminated optical film can form an image display device such as a liquid crystal display (LCD), an organic light-emitting diode (EL) display, a CRT, or a PDP. [Background technology]

[0002] To improve poor visibility caused by external light reflection and background glare on the display screen of an image display device, an image display device is known in which a circular polarizing plate is placed on the viewing side of the display panel.

[0003] For example, Patent Document 1 below describes a polarizing plate composite comprising a linear polarizing plate, a half-wavelength layer, a first adhesive layer formed by curing an active energy ray curable adhesive, and a quarter-wavelength layer in this order, wherein the angle between the phase-advancing axis of the half-wavelength layer and the transmission axis of the linear polarizing plate is 10° or more and 20° or less, and the absolute value of the difference between the refractive index of the first adhesive layer at a wavelength of 589 nm and the refractive index of the half-wavelength layer in the direction of the phase-advancing axis at a wavelength of 589 nm is less than 0.05.

[0004] Furthermore, Patent Document 2 below describes a polarizing plate with phase difference layers, comprising a polarizer, a first phase difference layer, and a second phase difference layer in that order, wherein the polarizer and the first phase difference layer are bonded together via a first adhesive layer, the first phase difference layer and the second phase difference layer are bonded together via a second adhesive layer, the thickness of the first phase difference layer and the second phase difference layer is 5 μm or less, the average refractive index of the second adhesive layer is 1.55 or more, and the difference between the average refractive index of the first phase difference layer and the average refractive index of the second phase difference layer is less than 0.08.

[0005] Incidentally, in Patent Document 3 below, for the purpose of providing an active energy ray-curable resin composition and a cured product in which the balance of various properties required for an optical sheet or the like used in optical applications is achieved, a metal oxide nanoparticle (A), a phenoxybenzyl (meth)acrylate (B), and a bifunctional (meth)acrylate (C) having a (poly)alkylene glycol structure are contained. An active energy ray-curable resin composition is described.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] As a result of the intensive studies by the present inventors, it has been found that there is room for further improvement in the techniques described in Patent Documents 1 and 2 above when stably improving the refractive index of the interlayer adhesive of the laminated film. Incidentally, the technique described in Patent Document 3 above relates to an active energy ray-curable resin composition for manufacturing a lens sheet, and is not originally intended for applications in which at least three optical films are adhered. In addition, since the adhesive composition for laminated optical films is applied to the optical film with a considerably thin film thickness, when it contains metal oxide particles, it is required to have excellent liquid stability. However, the technique described in Patent Document 3 above has not considered such problems, and there is no description or suggestion regarding means for solving such problems.

[0008] This invention was developed in view of the above circumstances, and aims to provide a laminated optical film that suppresses interference unevenness and has excellent visibility, and an image display device equipped with the laminated optical film. [Means for solving the problem]

[0009] The above problems can be solved by the following configuration. That is, the present invention relates to a laminated optical film (1) in which a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film are laminated in this order, wherein the first adhesive layer and the second adhesive layer are cured layers of an adhesive composition for laminated optical films containing a curable component and metal oxide particles.

[0010] In the laminated optical film (1) described above, the laminated optical film (2) is preferable in which the adhesive composition for the laminated optical film has a content of 10 to 50% by mass of the metal oxide particles when the total amount in the composition is 100% by mass.

[0011] In the above-mentioned laminated optical film (1) or (2), a laminated optical film (3) is preferred in which the adhesive composition for the laminated optical film further contains a (meth)acrylate containing an aromatic ring skeleton.

[0012] In the laminated optical film (3) described above, the laminated optical film (4) is preferable in which the adhesive composition for the laminated optical film contains 30 to 70% by mass of (meth)acrylate containing the aromatic ring skeleton, when the total amount in the composition is 100% by mass.

[0013] In the above-mentioned laminated optical film (3), a laminated optical film (5) is preferred in which the (meth)acrylate containing the aromatic ring skeleton contains at least one selected from the group consisting of (meth)acrylate having a polycyclic aromatic ring skeleton and (meth)acrylate having two or more aromatic rings.

[0014] In the above-mentioned laminated optical film (3), a laminated optical film (6) in which the (meth)acrylate containing the aromatic ring skeleton is phenoxybenzyl (meth)acrylate is preferred.

[0015] In any of the above laminated optical films (1) to (6), a laminated optical film (7) is preferred in which the adhesive composition for the laminated optical film further contains a hydroxyl group-containing (meth)acrylate.

[0016] In the laminated optical film (7) described above, the laminated optical film (8) is preferable in which the content of the hydroxyl group-containing (meth)acrylate is 1 to 30% by mass when the total amount in the composition is 100% by mass.

[0017] Of the above laminated optical films (1) to (8), a laminated optical film (9) is preferred in which the viscosity of the adhesive composition for the laminated optical film at 25°C is 100 [mPa·s] or less.

[0018] In any of the above laminated optical films (1) to (9), a laminated optical film (10) is preferred in which the refractive index of both the first adhesive layer and the second adhesive layer is 1.55 or higher.

[0019] Of the above laminated optical films (1) to (10), a laminated optical film (11) is preferred in which the refractive indices of the first optical film and the second optical film are both 1.55 or higher.

[0020] In any of the above laminated optical films (1) to (11), a laminated optical film (12) in which both the first optical film and the second optical film are liquid crystal phase difference films is preferred.

[0021] In any of the above laminated optical films (1) to (12), a laminated optical film (13) is preferred in which the third optical film is a polarizing film comprising at least a polarizer.

[0022] In any of the above laminated optical films (1) to (13), a laminated optical film (14) in which the thickness of the first adhesive layer is 100 to 3000 nm is preferred.

[0023] Of the above laminated optical films (1) to (14), a laminated optical film (15) in which the thickness of the second adhesive layer is 100 to 3000 nm is preferred.

[0024] The present invention also relates to an image display device (16) comprising any of the above-mentioned laminated optical films (1) to (15).

[0025] Furthermore, the present invention relates to an organic EL display device (17) comprising any of the above-mentioned laminated optical films (1) to (15). [Effects of the Invention]

[0026] The laminated optical film according to the present invention is constructed by laminating three optical films using an adhesive layer formed from a cured layer of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. The cured layer of the adhesive composition for laminated optical films containing a curable component and metal oxide particles has (1) a high refractive index and (2) a reduced curing shrinkage rate. Due to (2) above, when the three optical films are laminated via the adhesive layer, the curing shrinkage of each adhesive layer is suppressed, and the occurrence of surface irregularities in the three optical films is suppressed. In addition, due to (1) above, the refractive index difference between each optical film and the adhesive layer can be reduced. Therefore, interference irregularities caused by surface irregularities in each optical film constituting the laminated optical film, as well as interference irregularities caused by the refractive index difference between each optical film and the adhesive layer, can be suppressed. As a result, the laminated optical film according to the present invention has excellent visibility because the occurrence of interference irregularities can be sufficiently suppressed.

[0027] In the laminated optical film according to the present invention, in particular when (i) the refractive index of the first adhesive layer and the second adhesive layer are both 1.55 or higher, (ii) the refractive index of the first optical film and the second optical film are both 1.55 or higher, and further when (iii) the first optical film and the second optical film are both liquid crystal phase difference films, the laminated optical film according to the present invention is particularly excellent in visibility because the occurrence of interference unevenness can be more effectively suppressed. Regarding (i) above, when the refractive index of the first adhesive layer and the second adhesive layer are both 1.55 or higher, the occurrence of interference unevenness in the laminated optical film can be more effectively suppressed due to the smaller refractive index difference with the laminated optical film, resulting in particularly excellent visibility of the laminated optical film. Regarding (ii) above, when the refractive index of the first optical film and the second optical film are both 1.55 or higher, similar to (i) above, the occurrence of interference unevenness in the laminated optical film can be more effectively suppressed, resulting in particularly excellent visibility of the laminated optical film. Regarding (iii) above, when both the first optical film and the second optical film are liquid crystal phase difference films, liquid crystal phase difference films are brittle and have poor shape retention, which makes them prone to surface irregularities and interference in the laminated optical film. However, in the laminated optical film according to the present invention, the first adhesive layer interposed between the first optical film and the second optical film, and the second adhesive layer in contact with the second optical film, are laminated using adhesive layers formed from a cured layer of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. Therefore, the curing shrinkage of the liquid crystal phase difference film caused by the curing shrinkage of the adhesive layer can be more effectively suppressed. Consequently, the occurrence of interference in the laminated optical film can be more effectively suppressed, which is preferable because it provides particularly excellent visibility of the laminated optical film. [Brief explanation of the drawing]

[0028] [Figure 1] An example of a laminated optical film according to the present invention [Modes for carrying out the invention]

[0029] Figure 1 shows an example of a laminated optical film according to the present invention. The laminated optical film 10 shown in Figure 1 is constructed by laminating a first optical film 1, a first adhesive layer 4, a second optical film 2, a second adhesive layer 5, and a third optical film 3 in this order. The adhesive composition for laminated optical films used in the present invention to form the first adhesive layer 4 and the second adhesive layer 5 has a high refractive index in its cured layer and suppresses curing shrinkage of the adhesive layer due to the stable dispersion of metal oxide particles. As a result, (a) the refractive index difference between the first optical film 1 and the first adhesive layer 4 can be reduced, the refractive index difference between the first adhesive layer 4 and the second optical film 2 can be reduced, and the refractive index between the second optical film 2 and the second adhesive layer 5 can be reduced. In addition, (b) due to the suppression of curing shrinkage of the first adhesive layer 4, the occurrence of surface irregularities on the first optical film 1 and the second optical film 2 can be suppressed, and due to the suppression of curing shrinkage of the second adhesive layer 5, the occurrence of surface irregularities on the second optical film 2 and the third optical film 3 can be suppressed. Therefore, the laminated optical film according to the present invention has excellent visibility because interference unevenness can be sufficiently suppressed. In particular, when a phase difference film, preferably a liquid crystal phase difference film, is used as the first optical film 1 and the second optical film 2, even though the phase difference film is brittle and has poor shape retention, the effects of (a) and (b) above can more effectively suppress interference unevenness in the laminated optical film and further improve visibility.

[0030] The third optical film 3 is preferably a polarizing film. Generally, polarizing films have a transparent protective film on one or both sides of the polarizer, but if the third optical film 3 is a polarizing film, the side of the third optical film 3 facing the second adhesive layer 5 may be a polarizer (from the display device side toward the viewing side, second adhesive layer 5 → polarizer → adhesive layer → transparent protective film). Alternatively, the side of the third optical film 3 facing the second adhesive layer 5 may be a transparent protective film (from the display device side toward the viewing side, second adhesive layer 5 → transparent protective film → adhesive layer → polarizer → adhesive layer → transparent protective film). With respect to the polarizing film, the adhesive layer for laminating the polarizer and the transparent protective film may be the same as the first adhesive layer 4 or the second adhesive layer 5, which are cured product layers of the adhesive composition for laminated optical films used in the present invention, or it may be a cured product layer of an adhesive composition known to those skilled in the art.

[0031] The laminated optical film according to the present invention is a laminated optical film in which a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film are laminated in this order, and may further include any optical film. The laminated optical film 10 shown in Figure 1 includes an organic light-emitting diode layer 7 below the first optical film 1 (on the display device side) via an adhesive layer 6.

[0032] The laminated optical film according to the present invention is a laminated optical film in which a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film are laminated in this order. The first adhesive layer and the second adhesive layer are formed of cured layers of an adhesive composition for laminated optical films containing a curable component and metal oxide particles.

[0033] The first and second adhesive layers are formed by cured layers of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. The adhesive compositions used for the first and second adhesive layers may have the same composition or different compositions. From the viewpoint of suppressing interference unevenness in the laminated optical film and improving visibility, the refractive index of the first and second adhesive layers is preferably 1.55 or higher, and more preferably 1.57 or higher. A preferred upper limit for the refractive index of the first and second adhesive layers is, for example, around 1.70. From the viewpoint of suppressing interference unevenness in the laminated optical film, it is preferable for the first and second adhesive layers to have a certain thickness. However, if the thickness of the adhesive layers is too thick, surface irregularities are likely to occur during curing, which is undesirable from the viewpoint of suppressing interference unevenness in the laminated optical film. Therefore, the thickness of the first adhesive layer is preferably 100 to 3000 nm, and more preferably 200 to 2000 nm. Similarly, the thickness of the second adhesive layer is preferably 100 to 3000 nm, and more preferably 200 to 2000 nm.

[0034] The following describes the adhesive compositions for laminated optical films that serve as raw materials for the first and second adhesive layers.

[0035] <Metal oxide particles> The adhesive composition for laminated optical films used in the present invention contains metal oxide particles. Examples of metal oxide particles include silicon oxide, zirconium oxide, titanium oxide, zinc oxide, antimony pentoxide, tin oxide, aluminum oxide, indium oxide, indium tin oxide, ferric oxide, cerium oxide, yttrium oxide, manganese oxide, holomium oxide, copper oxide, bismuth oxide, cobalt oxide, cobalt trioxide, iron trioxide, magnesium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, eurobium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, tantalum pentoxide, niobium pentoxide, iridium oxide, rhodium oxide, ruthenium oxide, and composite oxides formed by combining these. Among these, zirconium oxide and titanium oxide are preferred, and zirconium oxide is particularly preferred. The metal oxide particles used in this invention may consist solely of the metal oxides listed above, or they may contain other components, but it is preferable that metal oxides constitute the largest weight component in the particles. The shape of the metal oxide particles can be any shape, such as spherical, ellipsoidal, cuboidal, rectangular prism, or pyramidal. In this invention, metal oxide particles that have been surface-treated by methods known to those skilled in the art may be used.

[0036] From the viewpoint of improving the stability of metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the average particle size of the metal oxide particles used is preferably 1 to 150 nm, and more preferably 1 to 50 nm. In the present invention, the average particle size of the metal oxide particles can be calculated by observing them under magnification using a transmission electron microscope (TEM), field emission transmission electron microscope (FE-TEM), and field emission scanning electron microscope (FE-SEM), randomly selecting, for example, 1000 particles, measuring their maximum length, and calculating their arithmetic mean.

[0037] The average particle size of metal oxide particles incorporated into an adhesive composition can also be calculated using dynamic light scattering or laser diffraction. When calculated using dynamic light scattering or laser diffraction, the average particle size refers to the particle size at 50% of the integrated value in the particle size distribution obtained by laser diffraction / scattering.

[0038] From the viewpoint of improving the stability of metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the amount of metal oxide particles used is preferably 10 to 50% by mass, and more preferably 15 to 40% by mass, when the total amount in the composition is 100% by mass.

[0039] <Curing component> The adhesive composition for laminated optical films used in the present invention contains a curable component. In the present invention, the curable component is preferably an active energy ray curable component. Active energy ray curable components can be classified into radical polymerization curable components and cationic polymerization curable components. In the present invention, active energy rays with a wavelength range of 10 nm to less than 380 nm are referred to as ultraviolet rays, and active energy rays with a wavelength range of 380 nm to 800 nm are referred to as visible light.

[0040] The adhesive composition for laminated optical films used in the present invention may contain a monofunctional radical polymerizable compound as a curable component. Examples of monofunctional radical polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, examples include alkyl esters of (meth)acrylic acid (with 1-20 carbon atoms), such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0041] Furthermore, examples of the (meth)acrylic acid derivatives include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-ylmethyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyl oxy Examples include polycyclic (meth)acrylates such as ethyl (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 alkylphenoxypolyethylene glycol (meth)acrylate. Among these, dicyclopentenyloxyethyl acrylate and phenoxyethyl acrylate are preferred due to their excellent adhesion to various protective films.

[0042] Furthermore, the (meth)acrylic acid derivatives include hydroxyalkyl( )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 meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl(meth)acrylate; epoxy group-containing (meth)acrylates such as glycidyl(meth)acrylate and 4-hydroxybutyl(meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl(meth)acrylate and 2,2,2-trifluoroethyl(meth)acrylate Halogen-containing (meth)acrylates such as 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; 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate Examples include oxetane group-containing (meth)acrylates such as rilate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; and neopentyl glycol (meth)acrylic acid adducts of hydroxypivalate and p-phenylphenol (meth)acrylate. Among these, 2-hydroxy-3-phenoxypropyl acrylate is preferred due to its excellent adhesion to various protective films.

[0043] The adhesive composition for laminated optical films used in the present invention is preferable if it contains hydroxyl group-containing (meth)acrylate in addition to metal oxide particles and the compound represented by general formula (1), because this further improves the adhesive strength of the adhesive layer. From the viewpoint of improving the adhesive strength of the adhesive layer, the amount of hydroxyl group-containing (meth)acrylate blended is preferably 1 to 30% by mass, and more preferably 3 to 20% by mass, when the total amount in the composition is 100% by mass.

[0044] Furthermore, examples of monofunctional radical 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.

[0045] Examples of monofunctional radical polymerizable compounds include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and vinyl monomers having nitrogen-containing heterocyclic rings such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

[0046] Furthermore, as a monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. A radical polymerizable compound having an active methylene group is a compound that has an active double bond group such as a (meth)acrylic group at its terminal or in the molecule, and also has an active methylene group. Examples of active methylene groups 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 radical polymerizable compounds having an active methylene group include acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; 2-ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, and N-(2-acetoacetylaminoethyl)acrylamide. The radical polymerizable compound having an active methylene group is preferably an acetoacetoxyalkyl (meth)acrylate.

[0047] Furthermore, the adhesive composition for laminated optical films used in the present invention may contain a bifunctional or polyfunctional radical polymerizable compound as a curing component. Examples of polyfunctional radical polymerizable compounds 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, and bisphenol A diglycidyl ether di(meth)acrylate. Examples include esters of (meth)acrylic acid with polyhydric alcohols such as phosphate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 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, and EO-modified diglycerin tetra(meth)acrylate, as well as 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Aronics 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), and CD-536 (manufactured by Sartomer). Additionally, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and various (meth)acrylate monomers may be used as needed.Furthermore, polyfunctional (meth)acrylamide derivatives are preferable to include in adhesive compositions because they have a fast polymerization rate, excellent productivity, and excellent crosslinking properties when the adhesive composition is cured.

[0048] For example, when using polarizers and transparent protective films as optical films, it is preferable to use a combination of monofunctional and polyfunctional radical polymerizable compounds in order to achieve both adhesion to polarizers and various transparent protective films and optical durability in harsh environments. The amount of monofunctional radical polymerizable compound in the adhesive composition is preferably 10 to 95% by mass, and more preferably 30 to 80% by mass, when the total amount in the composition is 100% by mass. The amount of polyfunctional radical polymerizable compound in the adhesive composition is preferably 0.5 to 60% by mass, and more preferably 1 to 40% by mass, when the total amount in the composition is 100% by mass.

[0049] <(meth)acrylate containing an aromatic ring skeleton> The adhesive composition for laminated optical films used in the present invention is preferable if it contains a (meth)acrylate containing an aromatic ring skeleton together with metal oxide particles, as this improves the refractive index of the adhesive layer. From the viewpoint of more stably increasing the refractive index of the adhesive layer, in the present invention, it is preferable to use a (meth)acrylate containing an aromatic ring skeleton that contains at least one selected from the group consisting of (meth)acrylates having a polycyclic aromatic ring skeleton and (meth)acrylates having two or more aromatic rings. Examples of (meth)acrylates containing an aromatic ring skeleton include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1-naphthalenemethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, ethylene oxide-modified orthophenylphenol (meth)acrylate, and reaction products of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene and (meth)acrylic acid. Among these, the use of phenoxybenzyl (meth)acrylate and phenoxyethyl (meth)acrylate is more preferred, and the use of phenoxybenzyl (meth)acrylate is particularly preferred. Phenoxybenzyl (meth)acrylate is given by the following formula (A): [ka] The compound has a structure represented by the following formula (A): In the above formula (A), X represents a single bond forming part of an adjacent bonding group, or a structure having 1 to 5 repeating ethylene oxide, propylene oxide, butylene oxide, or styrene oxide structures. R represents a hydrogen atom or a methyl group. The adhesive composition for laminated optical films used in the present invention is the following formula (A-1): [ka] It is preferable to contain phenoxybenzyl (meth)acrylate, which is an o- or m-substituted derivative represented by .

[0050] From the viewpoint of improving the refractive index of the adhesive layer, the amount of (meth)acrylate containing an aromatic ring skeleton used, particularly phenoxybenzyl (meth)acrylate, is preferably 30 to 70% by mass when the total amount in the composition is 100% by mass.

[0051] <Compounds represented by general formula (1)> The adhesive composition for laminated optical films used in this invention, together with metal oxide particles, follows the general formula (1): [ka] A compound represented by (where X is a reactive group, Y is a C1-C12 alkylene group which may have a branched chain, or a phenylene group which may have a substituent, R 1 and R 2 It is preferable that the adhesive strength of the adhesive layer is further improved if each of the following elements independently contains a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group, or a heterocyclic group. In addition, if the adhesive composition for laminated optical films used in the present invention contains the compound represented by the above general formula (1) together with metal oxide particles, the curing shrinkage rate of the adhesive layer is reduced. Therefore, it is preferable because the stress applied to each optical film can be reduced when the laminated optical film is formed, and an improvement in the durability of the laminated optical film can be expected.

[0052] Examples of the aliphatic hydrocarbon group include linear or branched alkyl groups which may have substituents having 1 to 20 carbon atoms, cyclic alkyl groups which may have substituents having 3 to 20 carbon atoms, and alkenyl groups which have 2 to 20 carbon atoms. Examples of the aryl group include phenyl groups which may have substituents having 6 to 20 carbon atoms, and naphthyl groups which may have substituents having 10 to 20 carbon atoms. Examples of the heterocyclic group include 5-membered or 6-membered ring groups which may have substituents and contain at least one heteroatom. These may be linked together to form a ring. In general formula (1), R 1 and R 2 Preferably, the member is a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom.

[0053] The X in the compound represented by general formula (1) is a reactive group, a functional group that can react with the curable components constituting the cured layer, particularly the adhesive layer, and examples include hydroxyl groups, amino groups, aldehyde groups, carboxyl groups, vinyl groups, (meth)acrylic groups, styryl groups, (meth)acrylamide groups, vinyl ether groups, epoxy groups, oxetane groups, α,β-unsaturated carbonyl groups, mercapto groups, halogen groups, and the like. When the curable resin composition constituting the cured layer, particularly the adhesive layer, is curable by active energy rays, the reactive group X is preferably at least one reactive group selected from the group consisting of vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, and mercapto group. When the curable resin composition constituting the cured layer, particularly the adhesive layer, is radical polymerizable, the reactive group X is preferably at least one reactive group selected from the group consisting of (meth)acrylic group, styryl group, and (meth)acrylamide group. When the compound represented by general formula (1) has a (meth)acrylamide group, it is more preferable because it is highly reactive and increases the copolymerization rate with the curable component in the cured layer, particularly the adhesive layer. Furthermore, it is also preferable because the (meth)acrylamide group has high polarity and excellent adhesiveness, which allows the effects of the present invention to be obtained efficiently. When the curable resin composition constituting the cured layer, particularly the adhesive layer, is cationic polymerizable, the reactive group X preferably has at least one functional group selected from hydroxyl group, amino group, aldehyde, carboxyl group, vinyl ether group, epoxy group, oxetane group, and mercapto group. The presence of an epoxy group is particularly preferable because it provides excellent adhesion between the resulting cured layer, particularly the adhesive layer, and the adherend, and the presence of a vinyl ether group is preferable because it provides excellent curability of the curable resin composition.

[0054] Preferred specific examples of compounds represented by general formula (1) include the following compounds (1a) to (1d). Note that R in general formulas (1a) and (1b) 3 This is either a hydrogen atom or a methyl group. [ka]

[0055] In addition to the compounds exemplified above, examples of compounds represented by general formula (1) include esters of (meth)acrylates and boric acid, such as esters of hydroxyethyl acrylamide and boric acid, esters of methylol acrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

[0056] From the standpoint of improving the adhesive strength of the adhesive layer, the amount of compound represented by general formula (1) used is preferably 0.1 to 10% by mass, and more preferably 0.3 to 5% by mass, when the total amount in the composition is 100% by mass.

[0057] The adhesive composition for laminated optical films used in the present invention contains at least one compound selected from the group consisting of isocyanurate compounds and polysiloxane compounds, thereby stably dispersing metal oxide particles. For this reason, despite containing metal oxide particles, the viscosity can be kept low. From the viewpoint of thinning the adhesive layer and the laminated optical film by thinning the adhesive composition onto the optical film, it is preferable to have a viscosity of 100 [mPa·s] or less, and more preferably 60 [mPa·s] or less, of the composition at 25°C.

[0058] <Leveling agent> The adhesive composition for laminated optical films used in the present invention preferably contains at least one selected from the group consisting of isocyanurate compounds and polysiloxane compounds as a leveling agent. By including at least one selected from the group consisting of isocyanurate compounds and polysiloxane compounds in the composition, the metal oxide particles are stably dispersed, resulting in excellent liquid stability of the adhesive composition for laminated optical films. Furthermore, by including metal oxide particles and at least one selected from the group consisting of isocyanurate compounds and polysiloxane compounds in the composition, the generation of repellency and bubbles during coating on the optical film can be suppressed. From the viewpoint of further enhancing the above effects, the adhesive composition for laminated optical films used in the present invention preferably contains both isocyanurate compounds and polysiloxane compounds. When the adhesive composition for laminated optical films contains both isocyanurate compounds and polysiloxane compounds, the amount of each compound is preferably 0.1 to 4% by mass, and more preferably 0.1 to 2% by mass, when the total amount in the composition is 100% by mass. Furthermore, as described later, when an isocyanurate compound is also used as a crosslinking agent, if the adhesive composition for laminated optical films contains both an isocyanurate compound and a polysiloxane compound, the amount of each compound used is preferably 0.1 to 14% by mass, and more preferably 0.1 to 7% by mass, when the total amount in the composition is considered as 100% by mass.

[0059] <Isocyanurate compounds> Isocyanurate compounds are compounds containing an isocyanurate ring structure formed by the trimerization reaction of isocyanates. In the present invention, it is particularly preferable to use a modified isocyanurate compound having a reactive group. Examples of reactive groups in modified isocyanurate compounds include polymerizable functional groups, specifically radical polymerizable functional groups having an ethylenically double bond, such as (meth)acryloyl groups, vinyl groups, and allyl groups; epoxy groups such as glycidyl groups; and cationic polymerizable functional groups such as oxetane groups, vinyl ether groups, cyclic ether groups, cyclic thioether groups, and lactone groups. From the viewpoint of reactivity in the adhesive composition for laminated optical films, a modified isocyanurate compound having a double bond as the reactive group is preferred, and a modified isocyanurate compound having a (meth)acryloyl group is more preferred. The amount of isocyanurate compound blended in the adhesive composition for laminated optical films is preferably 0.05 to 2% by mass, and more preferably 0.05 to 1% by mass, when the total amount in the composition is 100% by mass.

[0060] Furthermore, isocyanurate compounds not only contribute to stabilizing the dispersion of metal oxide particles in the composition, but also have the effect of reducing the curing shrinkage rate when used as an adhesive layer, for example. Therefore, when isocyanurate compounds are incorporated as a crosslinking agent in the adhesive composition for laminated optical films used in the present invention, it is preferable to incorporate a larger amount of isocyanurate compounds. Specifically, when the total amount in the composition is 100% by mass, it is preferable to incorporate 0.05 to 10% by mass, and more preferably 0.05 to 5% by mass.

[0061] <Polysiloxane compounds> Polysiloxane compounds are compounds having a polysiloxane skeleton, such as polydimethylsiloxane. In the present invention, it is particularly preferable to use a modified polysiloxane compound having a reactive group. Examples of reactive groups in a modified polysiloxane compound include polymerizable functional groups, specifically radical polymerizable functional groups having an ethylenically double bond, such as (meth)acryloyl groups, vinyl groups, and allyl groups; epoxy groups such as glycidyl groups; and cationic polymerizable functional groups such as oxetane groups, vinyl ether groups, cyclic ether groups, cyclic thioether groups, and lactone groups. From the viewpoint of reactivity in the adhesive composition for laminated optical films, a modified polysiloxane compound having a double bond as the reactive group is preferred, and a modified polysiloxane compound having a (meth)acryloyl group is more preferred. The amount of polysiloxane compound blended in the adhesive composition for laminated optical films is preferably 0.05 to 2% by mass, and more preferably 0.05 to 1% by mass, when the total amount in the composition is 100% by mass.

[0062] The adhesive composition for laminated optical films used in the present invention can be used as an active energy ray curable adhesive composition when the curable component is used as an active energy ray curable component. When an electron beam or the like is used as the active energy ray, it is not necessary for the active energy ray curable adhesive composition to contain a photopolymerization initiator, but when ultraviolet light or visible light is used as the active energy ray, it is preferable to include a photopolymerization initiator.

[0063] The photopolymerization initiator is appropriately selected based on the active energy ray. When curing is performed by ultraviolet or visible light, a photopolymerization initiator that undergoes ultraviolet or visible light cleavage is used. Examples of the aforementioned photopolymerization initiators include benzophenone compounds such as benzyl, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzioin methyl ether, benzioin ethyl ether, benzoin isopropyl ether, and Examples include benzoin ether compounds such as benzoin butyl ether and anisoin methyl ether; aromatic ketal compounds such as benzyldimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

[0064] The amount of the photopolymerization initiator is preferably 0.5 to 5% by mass, and more preferably 1 to 4% by mass, when the total amount in the composition is considered as 100% by mass.

[0065] When using the active energy ray-curable adhesive composition as a visible light-curable type, it is particularly preferable to use a photoinitiator that is highly sensitive to light of 380 nm or more. A photoinitiator that is highly sensitive to light of 380 nm or more will be described later.

[0066] As the photoinitiator, a compound represented by the following general formula (3);

Chemical formula

[0067] Also, it is preferable to add a polymerization initiation aid 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, etc., and ethyl 4-dimethylaminobenzoate is particularly preferable. When using the polymerization initiation aid, the addition amount is preferably 0.1 to 2% by mass, and more preferably 0.3 to 1% by mass when the total amount in the composition is 100% by mass.

[0068] Furthermore, known photopolymerization initiators can be used in combination as needed. Since the optical functional layer and substrate film having UV absorption ability do not transmit light below 380 nm, it is preferable to use a photopolymerization initiator that is highly sensitive to light above 380 nm. Specifically, examples include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium.

[0069] In the present invention, it is preferable that the adhesive composition for laminated optical films contains an acrylic oligomer obtained by polymerizing (meth)acrylic monomers. By including an acrylic oligomer in the adhesive composition for laminated optical films, curing shrinkage when the composition is irradiated and cured with active energy rays can be reduced, and interfacial stress between the adhesive layer and the optical film can be reduced. As a result, a decrease in adhesion between the adhesive layer and the optical film can be suppressed.

[0070] Adhesive compositions for laminated optical films are preferably low viscosity when considering workability and uniformity during coating; therefore, acrylic oligomers obtained by polymerizing (meth)acrylic monomers are also preferably low viscosity. Acrylic oligomers that are low viscosity and can prevent curing shrinkage of the adhesive layer are preferably those with a weight-average molecular weight (Mw) of 15,000 or less, more preferably 10,000 or less, and particularly preferably 5,000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the cured layer (adhesive layer), the weight-average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1,000 or more, and particularly preferably 1,500 or more. Examples of (meth)acrylic monomers that constitute acrylic oligomers include, specifically, 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,Alkyl esters of (meth)acrylic acid (C1-C20) such as 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, and also, for example, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl ( (meth)acrylates, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (e.g., 2,2,2-trifluoroethyl (meth)acrylate, 2,2Examples include 2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc., and alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate). These (meth)acrylates can be used alone or in combination of two or more types. Specific examples of acrylic oligomers (E) include "ARUFON" from Toagosei Co., Ltd., "Actflow" from Soken Chemical Co., Ltd., and "JONCRYL" from BASF Japan.

[0071] The amount of acrylic oligomer in the adhesive composition for laminated optical films is preferably 3 to 40% by mass, and more preferably 5 to 20% by mass.

[0072] The adhesive composition for laminated optical films used in the present invention may contain a silane coupling agent. Specific examples of silane coupling agents include active energy ray curable compounds such as vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane.

[0073] Preferably, these are 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0074] Specific examples of silane coupling agents that are not curable by active energy rays other than those mentioned above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatetopropyltriethoxysilane, and imidazolesilane.

[0075] The adhesive composition for laminated optical films used in the present invention may be a cationic polymerization curable adhesive composition. Curable components (cationic polymerizable compounds) used in cationic polymerization curable adhesive compositions are classified into monofunctional cationic polymerizable compounds having one cationic polymerizable functional group in the molecule, and polyfunctional cationic polymerizable compounds having two or more cationic polymerizable functional groups in the molecule. Monofunctional cationic polymerizable compounds have relatively low liquid viscosity, so their inclusion in a cationic polymerization curable adhesive composition can reduce the liquid viscosity. Furthermore, monofunctional cationic polymerizable compounds often have functional groups that exhibit various functions, and their inclusion in a cationic polymerization curable adhesive composition can enable the cationic polymerization curable adhesive composition and / or the cured product of the cationic polymerization curable adhesive composition to exhibit various functions. Polyfunctional cationic polymerizable compounds can cause three-dimensional crosslinking of the cured product of a cationic polymerization curable resin composition, so their inclusion in a cationic polymerization curable adhesive composition is preferable. The ratio of monofunctional cationic polymerizable compound to polyfunctional cationic polymerizable compound is preferably such that the polyfunctional cationic polymerizable compound is mixed in an amount ranging from 10% to 1000% by mass per 100% by mass of the monofunctional cationic polymerizable compound. Examples of cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Examples of compounds having epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. The cationic polymerizable resin composition of the present invention is particularly preferably composed of alicyclic epoxy compounds because it exhibits excellent curability and adhesion.Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, caprolactone-modified, trimethylcaprolactone-modified, and valerolactone-modified 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, specifically Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2083, and Celoxide 2085 (all manufactured by Daicel Chemical Industries, Ltd., and available in Cyracure UVR-61). Examples include 05, Cyracure UVR-6107, Cyracure 30, and R-6110 (all manufactured by Dow Chemical Japan Ltd.). Compounds having an oxetanyl group are preferable to include because they have the effect of improving the curability of cationic polymerizable adhesive compositions and reducing the liquid viscosity of the composition. Compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, and di[(3-ethyl-3- Examples include xetanyl(methyl)ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenol novolac oxetane. Aronoxetane OXT-101, Aronoxetane OXT-121, Aronoxetane OXT-211, Aronoxetane OXT-221, and Aronoxetane OXT-212 (all manufactured by Toagosei Co., Ltd.) are commercially available. Compounds having a vinyl ether group are preferable to include because they improve the curability of cationic polymerizable adhesive compositions and reduce the liquid viscosity of the composition. Examples of compounds having an ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and pentaerythritol-type tetravinyl ether.

[0076] Cationic polymerization curable adhesive compositions contain at least one compound selected from the epoxy group-containing compounds, oxetanyl group-containing compounds, and vinyl ether group-containing compounds described above as curable components, all of which cure by cationic polymerization; therefore, a photocationic polymerization initiator is included. This photocationic polymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, and electron beams, and initiates the polymerization reaction of epoxy groups and oxetanyl groups. As the photocationic polymerization initiator, the photoacid generator described later is preferably used. Furthermore, when using a cationic polymerization adhesive composition that is curable with visible light, it is preferable to use a photocationic polymerization initiator that is particularly sensitive to light of 380 nm or higher. However, since photocationic polymerization initiators are generally compounds that show maximum absorption around 300 nm or shorter wavelengths, by incorporating a photosensitizer that shows maximum absorption in a longer wavelength range, specifically light with wavelengths longer than 380 nm, it is possible to stimulate light of this wavelength range and promote the generation of cationic species or acids from the photocationic polymerization initiator. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organosulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducing dyes. Two or more of these may be used in combination. Anthracene compounds are particularly preferred due to their excellent photosensitizing effect, and specific examples include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.). The photosensitizer content is preferably 0.1% to 5% by mass, and more preferably 0.5% to 3% by mass.

[0077] In the present invention, the adhesive composition for laminated optical films may contain a photoacid generator. When the adhesive composition for laminated optical films contains a photoacid generator, the water resistance and durability of the adhesive layer can be dramatically improved compared to when it does not contain a photoacid generator. The photoacid generator can be represented by the following general formula (4).

[0078] [ka] (However, L + represents any onium cation. Also, X - PF66 - SbF6 - AsF6 - SbCl6 - , BiCl5 - SnCl6 - ClO4 - (This represents a counteranion selected from the group consisting of dithiocarbamate anions and SCN-.)

[0079] Next, the counter anion X in general formula (4) - I will explain this.

[0080] Counter anion X in general formula (4) - While not particularly limited in principle, non-nucleophilic anions are preferred. Counter anion X - When the anion is non-nucleophilic, nucleophilic reactions are less likely to occur with coexisting cations within the molecule or with various materials used in combination. As a result, it is possible to improve the long-term stability of the photoacid generator itself, represented by general formula (4), and the compositions using it. A non-nucleophilic anion here refers to an anion with a low ability to undergo nucleophilic reactions. An example of such an anion is PF6. - SbF6 - AsF6 - SbCl6 - , BiCl5 - SnCl6 - ClO4 - , B(C6H5)4 - , dithiocarbamate anion, SCN - These are some examples.

[0081] Specifically, "Cyracure UVI-6992", "Cyracure UVI-6974" (both manufactured by Dow Chemical Japan Ltd.), "ADEKA Optomer SP150", "ADEKA Optomer SP152", "ADEKA Optomer SP170", "ADEKA Optomer SP172" (all manufactured by ADEKA Corporation), "Omnicat 250" (manufactured by IGM Resins BV), "CI-5102", "CI-2855" (both manufactured by Nippon Soda Co., Ltd.), "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-180L" (all manufactured by Sanshin Chemical Co., Ltd.), "IK-1", "CPI-100P", "CPI-101A", "CPI-110P", "CPI-200K", "CPI-210S", "CPI- Preferred specific examples of the photoacid generator of the present invention include "310B", "CPI-410B", "CPI-410S" (all manufactured by Sunapro Co., Ltd.), "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0082] The laminated optical film according to the present invention is a laminated optical film in which a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film are laminated in this order, wherein the first adhesive layer and the second adhesive layer are cured layers of the adhesive composition for laminated optical films described above.

[0083] The adhesive composition for laminated optical films used in the present invention contains metal oxide particles, but if it further contains at least one selected from the group consisting of isocyanurate compounds and polysiloxane compounds, the viscosity of the composition can be kept low due to the stable dispersion of the metal oxide particles. Therefore, the adhesive composition for laminated optical films can be thinly coated onto the optical film, and thus the thickness of the adhesive layer can be reduced.

[0084] Examples of the first to third optical films constituting the laminated optical film in the present invention include a polarizer, a transparent protective film, a phase difference film, and a polarizing film having a transparent protective film on one or both sides of the polarizer.

[0085] In the present invention, the polarizer is not particularly limited and various types can be used. Examples of polarizers include hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and partially saponified ethylene-vinyl acetate copolymer films, to which iodine is adsorbed and then uniaxially stretched. Examples of polarizer thickness include 3 to 20 μm.

[0086] However, in this invention, from the viewpoint of improving heat resistance in harsh environments at high temperatures, it is preferable to use a thin polarizer with a thickness of 3 μm or more and 15 μm or less as the polarizer. It is particularly preferable that the thickness be 12 μm or less, even more preferably 10 μm or less, and especially preferably 8 μm or less. Such thin polarizers have less thickness variation, excellent visibility, and excellent resistance to thermal shock due to minimal dimensional change.

[0087] A polarizer made by dyeing a polyvinyl alcohol-based film with iodine and then uniaxially stretching it can be produced, for example, by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and then stretching it to 3 to 7 times its original length. Boric acid, zinc sulfate, zinc chloride, etc., may be included as needed, or the film may be immersed in an aqueous solution of potassium iodide, etc. Furthermore, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water removes dirt and anti-blocking agents from the film surface, and also prevents uneven dyeing by swelling the film. Stretching may be performed after dyeing with iodine, while dyeing, or after stretching. Stretching can also be performed in aqueous solutions of boric acid or potassium iodide, or even in a water bath.

[0088] It is preferable for the polarizer to contain boric acid from the viewpoint of stretch stability and humidification reliability. Furthermore, from the viewpoint of suppressing the occurrence of through cracks, the boric acid content in the polarizer is preferably 22% by mass or less, and more preferably 20% by mass or less, relative to the total amount of the polarizer. From the viewpoint of stretch stability and humidification reliability, the boric acid content relative to the total amount of the polarizer is preferably 10% by mass or more, and more preferably 12% by mass or more.

[0089] Typical examples of thin polarizers include, Patent No. 4751486 specification, Patent No. 4751481 specification, Patent No. 4815544 specification, Patent No. 5048120 specification, International Publication No. 2014 / 077599 pamphlet, International Publication No. 2014 / 077636 pamphlet, Examples include thin polarizers described in the text or thin polarizers obtained from the manufacturing methods described therein.

[0090] As for the thin polarizers, among manufacturing methods that include a step of stretching in a laminated state and a step of dyeing, those obtained by a manufacturing method that includes a step of stretching in a boric acid aqueous solution, as described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, and Japanese Patent No. 4815544, are preferred because they can be stretched to a high magnification and their polarization performance can be improved. In particular, those obtained by a manufacturing method that includes a step of auxiliary air stretching before stretching in a boric acid aqueous solution, as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544, are preferred. These thin polarizers can be obtained by a manufacturing method that includes a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin substrate in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to stretch it without problems such as breakage due to stretching because it is supported by the stretching resin substrate.

[0091] As materials constituting the transparent protective film, for example, thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy are used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose resin films, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain one or more suitable additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the above thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, even more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. If the content of the above-mentioned thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency and other properties inherent to the thermoplastic resin may not be fully realized.

[0092] Furthermore, the material used to form the transparent protective film is preferably one that is excellent in terms of transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy, and is particularly good if it has a moisture permeability of 150 g / m². 2 It is more preferable that the amount is 24 hours or less, and 140 g / m² 2 Products with a shelf life of 24 hours or less are particularly preferred, and the density is 120 g / m². 2 Even better are those with a shelf life of 24 hours or less.

[0093] Functional layers such as a hard coat layer, anti-reflective layer, anti-sticking layer, diffusion layer, or anti-glare layer can be provided on the surface of the transparent protective film to which the polarizer is not attached. These functional layers can be provided on the transparent protective film itself, or they can be provided separately from the transparent protective film.

[0094] The thickness of the transparent protective film can be determined as appropriate, but generally it is about 1 to 500 μm, preferably 1 to 300 μm, and more preferably 5 to 200 μm, considering factors such as strength, workability, and thinness. Furthermore, 10 to 200 μm is preferred, and 20 to 80 μm is preferred.

[0095] As the transparent protective film, a phase difference film having a front phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a phase difference film is used as the transparent protective film, the phase difference film also functions as a transparent protective film, thus enabling a thinner design.

[0096] Examples of phase difference films include birefringent films made by uniaxial or biaxial stretching of polymer materials, orientation films of liquid crystal polymers, and films in which an orientation layer of liquid crystal polymer is supported by a film. There are no particular restrictions on the thickness of the phase difference film, but it is generally around 1 to 150 μm.

[0097] As for the phase difference film, the following formulas (1) to (3): 0.70 <Re

[0450] / Re

[0550] <0.97···(1) 1.5 × 10 -3 <Δn<6×10 -3 ...(2) 1.13 <NZ<1.50···(3) A reverse wavelength-dispersive phase difference film that satisfies the following equation may also be used: (In the formula, Re

[0450] and Re

[0550] are the in-plane phase difference values ​​of the phase difference film measured with light of wavelengths 450 nm and 550 nm at 23°C, respectively; Δn is the in-plane birefringence nx-ny when the refractive indices in the slow axis direction and the fast axis direction of the phase difference film are nx and ny, respectively; and NZ is the ratio of the thickness-direction birefringence nx-nz to the in-plane birefringence nx-ny when nz is the refractive index in the thickness direction of the phase difference film).

[0098] In the laminated optical film according to the present invention, a phase difference layer may be provided. The phase difference layer may be a single layer or multiple layers, and the phase difference layer may also serve as a protective layer for the polarizer.

[0099] Liquid crystalline compounds are preferably used to form the phase difference layer. A solvent containing the liquid crystalline compound can be applied using, for example, a wire bar, gap coater, comma coater, gravure coater, or slot die. The applied liquid crystalline solution may be air-dried or heat-dried. It is preferable to apply the liquid crystalline solution at a concentration lower than the isotropic phase-liquid crystal phase transition concentration, i.e., in an isotropic phase state. In this case, the solution can be stably oriented by methods such as rubbing or photo-alignment.

[0100] The phase difference film included in the laminated optical film according to the present invention is preferably a liquid crystal phase difference film. Liquid crystal phase difference films are generally thin, for example, 5 μm or less in thickness. Due to their brittleness and poor shape retention, liquid crystal phase difference films are prone to surface irregularities, which can easily cause interference unevenness in the laminated optical film. However, in the laminated optical film according to the present invention, the first adhesive layer interposed between the first optical film and the second optical film, and the second adhesive layer in contact with the second optical film, are laminated using adhesive layers formed from a cured layer of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. Therefore, curing shrinkage of the liquid crystal phase difference film can be more effectively suppressed. Consequently, interference unevenness in the laminated optical film can be more effectively suppressed, and the visibility of the laminated optical film is particularly excellent, making it preferable.

[0101] In the laminated optical film according to the present invention, the refractive index of the first optical film and the second optical film is preferably 1.55 or higher, and more preferably 1.57 or higher. A preferred upper limit for the refractive index of the first optical film and the second optical film is, for example, about 1.70.

[0102] The laminated optical film according to the present invention can be manufactured, for example, by the following manufacturing method. A method for manufacturing a laminated optical film in which a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film are laminated in this order, comprising: a first coating step of applying a laminated optical film adhesive composition to one or both of the bonding surfaces of the third optical film and the second optical film; a first bonding step of bonding the third optical film and the second optical film together; and a first bonding step of bonding the third optical film and the second optical film via a second adhesive layer formed by irradiating at least the laminated optical film adhesive composition with active energy rays from the side of the third optical film or the side of the second optical film. A method for manufacturing a laminated optical film, comprising: an adhesive step; a second coating step of applying an adhesive composition for laminated optical films to one or both of the bonding surfaces of the second optical film and the first optical film; a second bonding step of bonding the second optical film and the first optical film together; and a second bonding step of bonding the second optical film and the first optical film via a first adhesive layer formed by irradiating at least the adhesive composition for laminated optical films with active energy rays from the side of the second optical film or the side of the first optical film, wherein the adhesive composition for laminated optical films contains a curable component and metal oxide particles.

[0103] In the first and second coating processes described above, the method for applying the adhesive composition for laminated optical films to one or both of the bonding surfaces of each optical film is appropriately selected depending on the viscosity of the composition and the desired thickness. Examples include reverse coaters, gravure coaters (direct, reverse, and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, and rod coaters.

[0104] Furthermore, the first to third optical films may undergo surface modification treatment before the coating process. In particular, when a polarizer is used as the optical film, it is preferable to surface modify the polarizer. Examples of surface modification treatments include corona treatment, plasma treatment, and Itro treatment, with corona treatment being particularly preferred. Corona treatment generates reactive functional groups such as carbonyl groups and amino groups on the polarizer surface, improving adhesion to the adhesive layer. In addition, the ashing effect removes foreign matter from the surface and reduces surface irregularities, making it possible to create a laminated optical film with excellent appearance characteristics.

[0105] The first optical film (second optical film) and the second optical film (third optical film) are bonded together using a roll laminator or the like via the adhesive composition for laminated optical films that has been coated as described above (first bonding step and second bonding step).

[0106] After bonding the first optical film (second optical film) and the second optical film (third optical film), the adhesive composition for the laminated optical film is cured by irradiation with active energy rays (electron beams, ultraviolet rays, visible light, etc.) to form an adhesive layer. The irradiation direction of the active energy rays (electron beams, ultraviolet rays, visible light, etc.) can be any appropriate direction.

[0107] When irradiating with an electron beam, any suitable irradiation conditions can be adopted as long as they are conditions that can cure the adhesive composition for the laminated optical film. For example, the acceleration voltage for electron beam irradiation is preferably 5kV to 300kV, and more preferably 10kV to 250kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive and curing may be insufficient, and if the acceleration voltage exceeds 300kV, the penetrating force through the sample may be too strong and damage the first optical film and the second optical film. The irradiation dose is 5 to 100kGy, more preferably 10 to 75kGy. If the irradiation dose is less than 5kGy, the adhesive will not cure sufficiently, and if it exceeds 100kGy, the first optical film and the second optical film will be damaged, resulting in a decrease in mechanical strength and yellowing, and the predetermined optical properties cannot be obtained.

[0108] Electron beam irradiation is usually performed in an inert gas environment, but if necessary, it may be performed in air or under conditions with a small amount of oxygen introduced. Depending on the materials of the first and second optical films, by appropriately introducing oxygen, oxygen inhibition can be intentionally caused on the surfaces of the first and second optical films that are initially hit by the electron beam, thereby preventing damage to the first and second optical films and allowing the electron beam to be efficiently directed only at the adhesive.

[0109] When manufacturing the laminated optical film according to the present invention, it is preferable to use an active energy ray that includes visible light in the wavelength range of 380 nm to 450 nm, and more preferably an active energy ray that has the highest irradiation amount of visible light in the wavelength range of 380 nm to 450 nm. When ultraviolet light and visible light are used, and a transparent protective film with ultraviolet absorption capability (ultraviolet-opaque transparent protective film) is used as the optical film, light with wavelengths shorter than approximately 380 nm is absorbed, so light with wavelengths shorter than 380 nm does not reach the curable resin composition and does not contribute to its polymerization reaction. Furthermore, light with wavelengths shorter than 380 nm absorbed by the first optical film and the second optical film is converted into heat, causing the first optical film or the second optical film itself to generate heat, which can cause defects such as curling and wrinkling of the laminated optical film. Therefore, when ultraviolet and visible light are used in the present invention, it is preferable to use a device that does not emit light with a wavelength shorter than 380 nm as the active energy ray generator. More specifically, it is preferable that the ratio of the integrated illuminance in the wavelength range of 380 to 440 nm to the integrated illuminance in the wavelength range of 250 to 370 nm is 100:0 to 100:50, and more preferably 100:0 to 100:40. When manufacturing the laminated optical film according to the present invention, gallium-filled metal halide lamps and LED light sources that emit light in the wavelength range of 380 to 440 nm are preferred as active energy rays. Alternatively, light sources containing ultraviolet and visible light such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, incandescent bulbs, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, excimer lasers, or sunlight can be used, and ultraviolet light with a wavelength shorter than 380 nm can also be blocked using a bandpass filter. To improve the adhesion performance of the adhesive layer between the first optical film and the second optical film while preventing curling of the laminated optical film, it is preferable to use an active energy ray obtained by using a gallium-filled metal halide lamp and passing it through a bandpass filter capable of blocking light with wavelengths shorter than 380 nm, or to use an active energy ray with a wavelength of 405 nm obtained using an LED light source.

[0110] When manufacturing the laminated optical film according to the present invention in a continuous line, the line speed depends on the curing time of the adhesive composition for the laminated optical film, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and even more preferably 10 to 100 m / min. If the line speed is too low, productivity will be poor, or the damage to the first and second optical films will be too great, making it impossible to produce a laminated optical film that can withstand durability tests. If the line speed is too high, the curing of the adhesive composition for the laminated optical film will be insufficient, and the desired adhesion may not be obtained.

[0111] The laminated optical film according to the present invention may also be provided with an adhesive layer for bonding to other components such as liquid crystal cells. The adhesive used to form the adhesive layer is not particularly limited, but for example, an adhesive 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, adhesives that have excellent optical transparency, exhibit appropriate wettability, cohesiveness and adhesive properties, and have excellent weather resistance and heat resistance, such as acrylic adhesives, are preferably used.

[0112] The adhesive layer can be provided on one or both sides of the laminated optical film according to the present invention as a superimposed layer of different compositions or types. Furthermore, when provided on both sides, the adhesive layers on the front and back of the laminated optical film according to the present invention may have different compositions, types, or thicknesses. The thickness of the adhesive layer can be appropriately determined according to the intended use and adhesive strength, and is generally 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

[0113] For the exposed surface of the adhesive layer, a separator is temporarily attached and covered to prevent contamination until it is put into practical use. This prevents contact with the adhesive layer under normal handling conditions. As for the separator, apart from the thickness conditions mentioned above, suitable thin materials such as plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, or laminates thereof can be used, and may be coated with a suitable release agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide as needed, in accordance with conventional methods.

[0114] The laminated optical film according to the present invention can be preferably used in the formation of various devices such as liquid crystal display devices. The formation of liquid crystal display devices can be carried out in accordance with conventional methods. That is, liquid crystal display devices are generally formed by assembling components such as liquid crystal cells, polarizing films or laminated optical films, and, if necessary, lighting systems, and incorporating drive circuits. However, in the present invention, there are no particular limitations except for the use of the polarizing film or laminated optical film according to the present invention, and the formation can be carried out in accordance with conventional methods. Any type of liquid crystal cell can be used, such as TN type, STN type, or π type.

[0115] Appropriate liquid crystal display devices can be formed, such as liquid crystal display devices in which optical laminates are arranged on one or both sides of a liquid crystal cell, or in which a backlight or reflector is used in the illumination system. In this case, the optical laminate according to the present invention can be installed on one or both sides of the liquid crystal cell. When optical laminates are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, appropriate components such as diffusers, anti-glare layers, anti-reflective films, protective plates, prism arrays, lens array sheets, light diffusers, and backlights can be arranged in appropriate positions in one or more layers. [Examples]

[0116] The following describes some embodiments of the present invention, but the embodiments of the present invention are not limited to these.

[0117] (Preparation of adhesive compositions for laminated optical films) According to the formulation table in Table 1, the following components were mixed and stirred at 50°C for 1 hour to obtain adhesive compositions 1 to 8 for laminated optical films (in Table 1, adhesive compositions 1 to 8 are simply referred to as "adhesives 1 to 8"). The values ​​in the table represent weight percentages when the total amount of the composition is considered to be 100% by mass.

[0118] The materials constituting each of the adhesive compositions 1 to 8 for laminated optical films are shown below. (i) Metal oxide particles • Zirconia dispersion 1: Phenoxybenzyl acrylate dispersion of zirconium oxide with an average particle size of 8 nm (particle concentration 30% by weight) • Zirconia dispersion 2: Phenoxybenzyl acrylate dispersion of zirconium oxide with an average particle size of 20 nm (particle concentration 30% by weight) • Zirconia dispersion 3: Phenylglycidyl ether dispersion of zirconium oxide with an average particle size of 20 nm (particle concentration 30% by weight) (ii) (meth)acrylate containing an aromatic ring skeleton • Phenoxybenzyl acrylate: Product name "Light Acrylate POB-A", manufactured by Kyoeisha Chemical Co., Ltd. • 1-Naphthalene methyl acrylate: Product name "Light Acrylate NMT-A", manufactured by Kyoeisha Chemical Co., Ltd. (iii) Curable component (iii-1) Radical polymerizable compounds • Hydroxyl group-containing (meth)acrylate (4-hydroxybutyl acrylate): Product name "4HBA", manufactured by Mitsubishi Chemical Corporation. • Aliphatic difunctional acrylate (1,9-nonanediol diacrylate): Product name "Light Acrylate 1.9ND-A", manufactured by Kyoeisha Chemical Co., Ltd. • Acryloylmorpholin: Brand name "ACMO", manufactured by KJ Chemicals. • Bifunctional acrylate (tripropylene glycol diacrylate): Product name "Arronix M-220", manufactured by Toagosei Co., Ltd. (iii-2) Cationic polymerizable compounds • Alicyclic epoxy compound (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate): Trade name "CEL-2021P", manufactured by Daicel Corporation • Bifunctional oxetane compound (3-ethyl-3-(phenoxymethyl)oxetane): Trade name "OXT-221", manufactured by Toagosei Co., Ltd. • Aliphatic epoxy compound (1,6-hexanediol diglycidyl ether): Trade name "EX-212L", manufactured by Nagase ChemteX Corporation • Aromatic epoxy compound (1) (Bisphenol A type epoxy resin): Trade name "jER828", manufactured by Mitsubishi Chemical Corporation • Aromatic epoxy compound (2) (biphenyl epoxy resin): Trade name "EX-142-IM", manufactured by Nagase ChemteX Corporation • Aromatic oxetane compound (xylylene bisoxetane): Product name "OXT-121", manufactured by Toagosei Co., Ltd. • Aromatic epoxy compound (3) (p-tert-butylphenylglycidyl ether): Trade name "EX-146", manufactured by Nagase ChemteX Corporation (vi) Photopolymerization initiator • Photopolymerization initiator 1 (1-hydroxycyclohexyl phenyl ketone): Trade name "Omnirad 184", manufactured by IGM Resins BV. • Photopolymerization initiator 2 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide): trade name "Omnirad 819", manufactured by IGM Resins BV. • Photoacid generator (75% solution of Iodonium, (4-methylphenyl)[4-(2-methylpropyl)phenyl]-, hexafluorophosphate(1-) in propylene carbonate): Trade name "Omnicat 250", manufactured by IGM Resins BV. • Photosensitizer (diethylthioxanthone): Product name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd. (v) Leveling agent • Leveling agent 1 (a leveling agent containing a modified isocyanurate compound having a (meth)acryloyl group and a modified polysiloxane compound having a (meth)acryloyl group): Product name "BYK UV-3505", manufactured by BYK. • Leveling agent 2 (polyether-modified polydimethylsiloxane): Product name "BYK 3760", manufactured by BYK. The zirconia dispersions 1 to 3 described above were manufactured by the following method.

[0119] (Synthesis of dispersant A) 415 g (1 mol) of tristyrenated phenol and 1 g (0.018 mol) of potassium hydroxide were charged into an autoclave and mixed uniformly. Under conditions of 130°C, 352 g (8 mol) of ethylene oxide (EO) was added dropwise to the reaction system. After the addition of ethylene oxide was complete, the system was aged for 1 hour at 130°C while maintaining a pressure of 0.1 MPa to obtain an 8 mol EO adduct of tristyrenated phenol.

[0120] 767 g (1 mole) of the above tristyrenated phenol EO 8 molar adduct and 152 g (1.3 moles) of sodium monochloroacetate were placed in a reactor and stirred until homogenized. Next, 52 g of sodium hydroxide was added under conditions of the reaction system being 60°C, and the temperature was raised to 80°C and aged for 3 hours. After aging, it was cooled to 50°C, and 117 g (1.2 moles) of 98% sulfuric acid was added dropwise at the same temperature to obtain a white suspension. This white suspension was washed with distilled water, and the solvent was removed by vacuum distillation to obtain dispersant A.

[0121] (Preparation of Zirconia Dispersion 1) To 100 parts of a methanol dispersion of zirconium oxide (manufactured by Sakai Chemical Industry Co., Ltd., grade name "SZR-CM", average particle size (D50) based on dynamic light scattering method: 8 nm, zirconium oxide solid content concentration: 30%), 1.5 parts of dispersant A and 28.5 parts of m-phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate POB-A"; hereinafter referred to as "POB-A") were added and mixed. Then, the solvent was removed under reduced pressure using a rotary evaporator to obtain zirconia dispersion 1, which is a monomer dispersion of zirconium oxide. This zirconia dispersion 1 contains zirconium oxide / dispersant A / POB-A in a weight ratio of 50 / 2.5 / 47.5.

[0122] (Preparation of Zirconia Dispersion 2) To 100 parts of a methyl ethyl ketone dispersion of zirconium oxide (manufactured by Nissan Chemical Industries, grade name "OZ-S40K-AC", average particle size (D50) based on dynamic light scattering method: 20 nm, zirconium oxide solid content concentration: 30%), 1.5 parts of dispersant A and 28.5 parts of m-phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical, trade name "Light Acrylate POB-A"; hereinafter referred to as "POB-A") were added and mixed. Then, the solvent was removed under reduced pressure using a rotary evaporator to obtain zirconia dispersion 2, which is a monomer dispersion of zirconium oxide. This zirconia dispersion 2 contains zirconium oxide / dispersant A / POB-A in a weight ratio of 50 / 2.5 / 47.5.

[0123] (Preparation of zirconia dispersion 3) To 100 parts of a methyl ethyl ketone dispersion of zirconium oxide (manufactured by Nissan Chemical Industries, grade name "OZ-S40K-AC", average particle size (D50) based on dynamic light scattering method: 20 nm, zirconium oxide solid content concentration: 30%), 1.5 parts of dispersant A and 67.5 parts of phenyl glycidyl ether (manufactured by Nagase ChemteX, trade name "EX-142-IM") were added and mixed. Then, the solvent was removed under reduced pressure using a rotary evaporator to obtain zirconia dispersion 3, which is a monomer dispersion of zirconium oxide. This zirconia dispersion 3 contains zirconium oxide / dispersant A / EX-142-IM in a weight ratio of 30.3 / 1.5 / 68.2.

[0124] Table 1 shows the formulations of adhesive compositions 1 to 8 for laminated optical films.

[0125] [Table 1]

[0126] The materials that make up the laminated optical film are shown below.

[0127] <Manufacturing of polarizers> A laminate was formed by air-assisted stretching at a stretching temperature of 130°C from an amorphous PET substrate with a 9 μm thick PVA layer. Next, a colored laminate was formed by dyeing the stretched laminate. Furthermore, an optical film laminate containing a 5 μm thick PVA layer was formed by stretching the colored laminate in boric acid water at a stretching temperature of 65°C, integrally with the amorphous PET substrate, to achieve a total stretching ratio of 5.94 times. This two-stage stretching process resulted in an optical film laminate containing a 5 μm thick PVA layer, in which the PVA molecules in the PVA layer formed on the amorphous PET substrate were highly oriented, and the iodine adsorbed by dyeing formed a polyiodide ion complex highly oriented in one direction, constituting a thin polarizer.

[0128] <Transparent protective film> "TAC"; Triacetylcellulose (TAC) film (product name "TJ25UL", thickness 25μm, manufactured by Fujifilm Corporation)

[0129] <Photopolymerizable liquid crystal composition> A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242") was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (Bic Chemie's "BYK-360") and a photopolymerization initiator (IGM Resins' "Omnirad907") were added to this solution to prepare a liquid crystal composition solution. The amounts of the leveling agent and polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound.

[0130] <λ / 2 phase difference film> Using a biaxially oriented norbornene-based film (Zeonor Film, manufactured by Zeon Corporation, thickness: 33 μm, frontal retardation: 135 nm) as a substrate, the above liquid crystal composition was coated onto the substrate by a bar coater so that the phase difference was λ / 2, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the film was subjected to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2 A laminate was obtained in which a homogeneous oriented liquid crystal layer was provided by photocuring using ultraviolet light.

[0131] <λ / 4 phase difference film> Using a biaxially oriented norbornene-based film (Zeonor Film, manufactured by Nippon Zeon Co., Ltd., thickness: 33 μm, frontal retardation: 135 nm) as a substrate, the above liquid crystal composition was applied to the substrate by a bar coater so that the phase difference was λ / 4, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the film was subjected to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2 A laminate was obtained in which a homogeneous oriented liquid crystal layer was provided by photocuring using ultraviolet light.

[0132] <Polarizing film (1)> Using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, rotation speed 140% / line speed), and a corona treatment machine, the processing density was 50 W·min / m². 2Adhesive composition 8 is applied to the corona-treated surface of the PVA layer of the polarizer that has undergone corona treatment, and the treatment is performed using the same corona treatment machine at a density of 50 W·min / m². 2 The corona-treated side of the TAC film was bonded to the other side using a roll machine (bonding line speed: 15 m / min). Then, a visible light irradiation device (Heraus Light HAMMER10 Mark III, bulb: V-bulb, peak illuminance: 1600 mW / cm²) was used from the TAC film side. 2 Total irradiation dose 1000 / mJ / cm 2 The irradiance and cumulative irradiation dose of the active energy rays were measured using a Power Puck 2 (manufactured by EIT, UVV measurement). By curing the adhesive composition with active energy rays, a polarizing film (1) was produced in which an amorphous PET substrate, a polarizer, and a TAC film were laminated through the cured layer of the adhesive composition. The thickness of the cured layer of the adhesive composition was 1000 nm.

[0133] <Polarizing film (2) (Third optical film)> Next, the amorphous PET substrate of the polarizing film (1) is peeled off, and the polarizer surface of the peeled surface is treated with a corona treatment machine at a density of 50 W·min / m². 2 Corona treatment was performed using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, rotation speed 140% / line speed) and a corona treatment machine with a processing density of 50 W·min / m². 2 Adhesive composition 8 is applied to the corona-treated surface of the PVA layer of the polarizer that has undergone corona treatment, and the treatment is performed using the same corona treatment machine at a density of 50 W·min / m². 2 The corona-treated side of the TAC film was bonded to the other side using a roll machine (bonding line speed: 15 m / min). Then, a visible light irradiation device (Heraus Light HAMMER10 Mark III, bulb: V-bulb, peak illuminance: 1600 mW / cm²) was used from the TAC film side. 2 Total irradiation dose 1000 / mJ / cm 2The irradiance and cumulative irradiation dose of the active energy rays were measured using Power Puck 2 (manufactured by EIT, UVV measurement). By curing the adhesive composition with active energy rays, a polarizing film (2) (third optical film) was produced in which TAC films were laminated on both sides of the polarizer via the cured layer of the adhesive composition. The thickness of the cured layer of the adhesive composition was 1000 nm.

[0134] <Polarizing film (3)> One of the TAC films of the polarizing film (2) (third optical film) obtained above was treated with the same corona treatment machine as above at a treatment density of 50 W·min / m². 2 Corona treatment was performed. One of the adhesive compositions 1 to 8 for laminated optical films listed in Table 1 was applied to the corona-treated surface of the TAC film using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, rotation speed 140% / line speed), and the same corona treatment machine was used to perform a treatment at a density of 50 W·min / m². 2 The homogeneous oriented liquid crystal layer surface of a corona-treated λ / 2 phase difference film was bonded to the polarizer's transmission axis using a roll machine so that the lagging axis of the λ / 2 phase difference film was at a 15° angle to the polarizer's transmission axis (bonding line speed: 15 m / min). Subsequently, a visible light irradiation device (Heraus Light HAMMER10 Mark III, bulb: V-bulb, peak illuminance: 1600 mW / cm²) was used from the λ / 2 phase difference film side. 2 Total irradiation dose 1000 / mJ / cm 2 The irradiance and cumulative irradiation dose of the active energy rays were measured using a Power Puck 2 (manufactured by EIT, UVV measurement). By curing the adhesive composition for the laminated optical film by irradiating it with active energy rays, a polarizing film (3) was produced in which a λ / 2 phase difference film (second optical film) and a polarizing film (2) (third optical film) were laminated via a cured layer (second adhesive layer) of one of the adhesive compositions 1 to 8 for the laminated optical film. The thickness of the cured layer (second adhesive layer) of each of the above adhesive compositions 1 to 8 for the laminated optical film was 1300 nm.

[0135] (Examples of laminated optical film manufacturing) The biaxially oriented norbornene-based film of the polarizing film (3) is peeled off, and the λ / 2 phase difference film surface of the peeled surface is treated with a corona treatment machine at a treatment density of 50 W·min / m². 2 Corona treatment was performed. Using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, rotation speed 140% / line speed), one of the adhesive compositions 1 to 8 for laminated optical films listed in Table 1 was applied to the corona-treated λ / 2 phase difference film surface, and the same corona treatment machine was used to process the film at a density of 50 W·min / m². 2 The homogeneous oriented liquid crystal layer surface of a corona-treated λ / 4 phase difference film was bonded to the λ / 2 phase difference film surface using a roll machine so that the lagging axis of the λ / 4 phase difference film was at a 75° angle to the transmission axis of the polarizer (bonding line speed: 15 m / min). Subsequently, a visible light irradiation device (Heraus Light HAMMER10 Mark III, bulb: V-bulb, peak illuminance: 1600 mW / cm²) was used from the λ / 4 phase difference film side. 2 Total irradiation dose 1000 / mJ / cm 2 The irradiance and cumulative irradiation amount of the active energy rays were measured by irradiating with active energy rays using Power Puck 2 (manufactured by EIT, UVV measurement), and curing one of the adhesive compositions 1 to 9 for laminated optical films listed in Table 1. A λ / 4 phase difference film surface (first optical film) and a λ / 2 phase difference film (second optical film) were laminated via the cured layer (first adhesive layer) of the adhesive composition for laminated optical films, and a λ / 2 phase difference film (second optical film) and a polarizing film (2) (third optical film) were further laminated via the cured layer (second adhesive layer) of the adhesive composition for laminated optical films to produce a laminated optical film. The thickness of the cured layer (first adhesive layer) of the above adhesive compositions 1 to 8 for laminated optical films was 1300 nm each.

[0136] Details of each evaluation method are as follows:

[0137] <Liquid viscosity of adhesive compositions for laminated optical films> The viscosity of adhesive compositions 1 to 8 for laminated optical films was measured using a TVE22LT E-type viscometer manufactured by Toki Sangyo Co., Ltd.

[0138] <Measuring the refractive index of the adhesive layer (cured product of adhesive composition for laminated optical films)> A cycloolefin polymer film (COP film) was coated with the adhesive compositions for laminated optical films according to Examples 1-8 and Comparative Examples 1-2 (thickness 100 μm). The same COP film was then bonded to the coated surface, and the film was irradiated with the above-mentioned visible light using an active energy ray irradiation device to obtain a cured layer (single film) of the adhesive composition for laminated optical films according to Examples 1-8 and Comparative Examples 1-2. The refractive index in the plane and the refractive index in the thickness direction of the obtained cured layer were measured using a prism coupler SPA-4000 (manufactured by Cylon Technology), and the average values ​​of these measurements were taken as the average refractive index of the adhesive layer. The measurement temperature was 23°C, and the measurement wavelength was 594 nm.

[0139] <Curing shrinkage rate of adhesive compositions for laminated optical films> The curing shrinkage rate was measured using a CUSTRON EU201C resin curing shrinkage measuring device (manufactured by Acroedge Co., Ltd.) with a laser displacement meter, and the curing shrinkage rate was calculated according to the method described in Japanese Patent Application Publication No. 2013-104869.

[0140] <Interference unevenness in laminated optical films including polarizing films> The biaxially oriented norbornene-based films of the laminated optical films obtained in the examples and comparative examples were peeled off and attached to an aluminum reflector with a standard acrylic adhesive (film thickness 25 μm) on the λ / 4 phase difference film side. They were then visually observed under a three-wavelength fluorescent lamp and evaluated based on the following criteria. The evaluation results are shown in Table 2. ◎: No interference unevenness is visible. ○: Slight interference unevenness is visible, but acceptable. △: Interference irregularities are visible. ×: Strong interference unevenness is visible.

[0141] [Table 2]

[0142] In the laminated optical films of Comparative Examples 1 to 5, the refractive index parameter (|refractive index of the first optical film - refractive index of the first adhesive layer| + |refractive index of the second optical film - refractive index of the first adhesive layer| + |refractive index of the second optical film - refractive index of the second adhesive layer|), which indicates the overall magnitude of the refractive index difference between each optical film and each adhesive layer, is large. Furthermore, in the laminated optical films of Comparative Examples 1 to 5, surface irregularities occurred in the first to third optical films because neither the first adhesive layer nor the second adhesive layer was formed from a cured product layer of an adhesive composition for laminated optical films containing a curable component and metal oxide particles. As a result, as shown in Table 2, interference unevenness occurred in all of the laminated optical films of Comparative Examples 1 to 5, resulting in poor visibility.

[0143] [Table 3]

[0144] On the other hand, in the laminated optical films according to Examples 1 to 8, the refractive index parameter (|refractive index of the first optical film - refractive index of the first adhesive layer| + |refractive index of the second optical film - refractive index of the first adhesive layer| + |refractive index of the second optical film - refractive index of the second adhesive layer|), which indicates the overall magnitude of the refractive index difference between each optical film and each adhesive layer, is small. Furthermore, in the laminated optical films according to Examples 1 to 8, both the first adhesive layer and the second adhesive layer are formed from a cured layer of an adhesive composition for laminated optical films containing a curable component and metal oxide particles, so the occurrence of surface irregularities in the first to third optical films is suppressed. As a result, as shown in Table 2, it can be seen that the laminated optical films according to Examples 1 to 8 all exhibit excellent visibility due to the occurrence of interference unevenness. [Explanation of symbols]

[0145] 1. First optical film, 2. Second optical film, 3. Third optical film, 4. First adhesive layer, 5. Second adhesive layer, 6. Adhesive layer, 7. Organic light-emitting diode panel, 10. Laminated optical film

Claims

1. A laminated optical film comprising a first optical film, a first adhesive layer, a second optical film, a second adhesive layer, and a third optical film, laminated in this order. A laminated optical film characterized in that the first adhesive layer and the second adhesive layer are cured layers of an adhesive composition for laminated optical films containing a curable component and metal oxide particles.

2. The laminated optical film according to claim 1, wherein the adhesive composition for the laminated optical film contains 10 to 50% by mass of the metal oxide particles when the total amount in the composition is 100% by mass.

3. The laminated optical film according to claim 1, wherein the adhesive composition for the laminated optical film further contains a (meth)acrylate containing an aromatic ring skeleton.

4. The laminated optical film according to claim 3, wherein the adhesive composition for the laminated optical film contains 30 to 70% by mass of (meth)acrylate containing the aromatic ring skeleton, when the total amount in the composition is 100% by mass.

5. The laminated optical film according to claim 3, wherein the (meth)acrylate containing the aromatic ring skeleton contains at least one selected from the group consisting of (meth)acrylates having a polycyclic aromatic ring skeleton and (meth)acrylates having two or more aromatic rings.

6. The laminated optical film according to claim 3, wherein the (meth)acrylate containing the aromatic ring skeleton is phenoxybenzyl (meth)acrylate.

7. The laminated optical film according to claim 1, wherein the adhesive composition for the laminated optical film further contains a hydroxyl group-containing (meth)acrylate.

8. The laminated optical film according to claim 7, wherein the adhesive composition for the laminated optical film has a content of 1 to 30% by mass of the hydroxyl group-containing (meth)acrylate when the total amount in the composition is 100% by mass.

9. The laminated optical film according to claim 1, wherein the viscosity of the adhesive composition for the laminated optical film at 25°C is 100 [mPa·s] or less.

10. The laminated optical film according to claim 1, wherein the refractive index of both the first adhesive layer and the second adhesive layer is 1.55 or higher.

11. The laminated optical film according to claim 1, wherein the refractive index of both the first optical film and the second optical film is 1.55 or higher.

12. The laminated optical film according to claim 1, wherein both the first optical film and the second optical film are liquid crystal phase difference films.

13. The laminated optical film according to claim 1, wherein the third optical film is a polarizing film comprising at least a polarizer.

14. The laminate according to claim 1, wherein the thickness of the first adhesive layer is 100 to 3000 nm.

15. The laminated optical film according to claim 1, wherein the thickness of the second adhesive layer is 100 to 3000 nm.

16. An image display device comprising the laminated optical film described in claim 1.

17. An organic EL display device comprising the laminated optical film described in claim 1.

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