Layered optical film and image display device

Abstract

A layered optical film in which at least an iodine-based polarizer and an optical film are laminated with an adhesive layer therebetween, wherein the adhesive layer is a cured product layer of an adhesive composition containing at least a (meth)acrylate compound and a photopolymerization initiator, and the adhesive composition contains 70 parts by mass or more of a (meth)acrylate (A) having a cyclic hydrocarbon skeleton in the molecule on the basis of 100 parts by mass in total of the (meth)acrylate compound. The (meth)acrylate (A) is preferably a compound having 5-12 carbon atoms constituting the cyclic hydrocarbon skeleton in the molecule.

Description

Stacked optical films and image display devices

[0001] The present invention relates to a laminated optical film in which at least an iodine-based polarizer and an optical film are laminated via an adhesive layer. This laminated optical film can form image display devices such as mobile phones, car navigation systems, personal computer monitors, and televisions.

[0002] Image display devices such as mobile phones, car navigation systems, computer monitors, and televisions are equipped with laminated optical films in which multiple optical films are laminated with adhesive or tack layers in between. Transparent resin films such as phase difference films, polarizers, and transparent protective films are used as optical films.

[0003] In recent years, efforts have been made to improve the durability of laminated optical films so that image display devices can be used even under high temperature and high humidity conditions. For example, Patent Document 1 below describes an optical laminate comprising a polarizer, a first cured product layer, a phase difference layer, and an adhesive layer in that order, wherein the polarizer is made of a polyvinyl alcohol resin containing iodine, the first cured product layer is a cured product of an active energy curable composition, the phase difference layer includes at least one phase difference expression layer which is a polymer of a polymerizable liquid crystal compound, the adhesive layer has an iodine content of 900 mg / kg or less after the optical laminate is stored at a temperature of 80°C and a relative humidity of 90% for 250 hours, and the polarizer and the first cured product layer are in direct contact with the phase difference layer.

[0004] Japanese Patent Publication No. 2021-113969

[0005] As a result of diligent research by the present inventors, it was found that the technology described in Patent Document 1 above does not sufficiently suppress the corrosion of panels under high temperature and high humidity conditions, and there is room for further improvement.

[0006] The present invention was developed in view of the above circumstances, and aims to provide a laminated optical film in which at least an iodine-based polarizer and an optical film, particularly a phase difference film, are laminated via an adhesive layer, and which can sufficiently prevent corrosion of the panel or sensor of an image display device even when used under high temperature and high humidity conditions.

[0007] The above problems can be solved by the following configuration. That is, the present invention relates to a laminated optical film (1) in which at least an iodine-based polarizer and an optical film are laminated via an adhesive layer, wherein the adhesive layer is a cured layer of an adhesive composition containing at least a (meth)acrylate compound and a photopolymerization initiator, and the adhesive composition contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of the (meth)acrylate compound is 100 parts by mass.

[0008] In the above-mentioned laminated optical film (1), a laminated optical film (2) in which the optical film is a phase difference film is preferred.

[0009] In the above-mentioned laminated optical film (2), a laminated optical film (3) in which the phase difference film is a liquid crystal phase difference film is preferred.

[0010] In the above-mentioned laminated optical film (2) or (3), a laminated optical film (4) in which the thickness of the phase difference film is 5 μm or less is preferred.

[0011] Of the above laminated optical films (1) to (4), a laminated optical film (5) in which the thickness of the adhesive layer is 3 μm or less is preferred.

[0012] Of the above-mentioned laminated optical films (1) to (5), the laminated optical film (6) in which the thickness of the iodine-based polarizer is 8 μm or less is preferred.

[0013] In any of the above-mentioned laminated optical films (1) to (6), the laminated optical film (7) is preferable in which the (meth)acrylate (A) is a compound having 5 to 12 carbon atoms that constitute a cyclic hydrocarbon skeleton within the molecule.

[0014] In any of the above laminated optical films (1) to (7), a laminated optical film (8) is preferred in which the (meth)acrylate (A) is at least a bifunctional (meth)acrylate.

[0015] In any of the above laminated optical films (1) to (8), the (meth)acrylate (A) is the following formula (A1) to (A5); A laminated optical film (9) is preferred, which is at least one compound selected from the group consisting of the compounds described above.

[0016] In any of the above laminated optical films (1) to (9), a laminated optical film (10) is preferred in which the adhesive composition further contains a (meth)acrylate (B) containing a hydroxyl group.

[0017] In the laminated optical film (10) described above, a laminated optical film (11) is preferred in which the content of (meth)acrylate (A) relative to (meth)acrylate (B) is in the range of 2 to 6 times.

[0018] In the laminated optical film (9) or (11) described above, the adhesive composition preferably contains 5 to 25 parts by mass of the (meth)acrylate (B) when the total amount of the (meth)acrylate compound is 100 parts by mass, and the laminated optical film (12) is preferred.

[0019] Furthermore, the present invention relates to an image display device (13) comprising any of the above-mentioned laminated optical films (1) to (12).

[0020] Furthermore, the present invention relates to an organic EL display device (14) comprising any of the above-mentioned laminated optical films (1) to (12).

[0021] In the laminated optical film according to the present invention, the adhesive layer interposed between the iodine-based polarizer and the optical film, particularly the phase difference film, is formed by a cured layer of an adhesive composition containing a specific proportion of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule. Therefore, even when used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device can be sufficiently prevented. The reason for achieving this effect can be presumed to be as follows.

[0022] When a laminated optical film, in which at least an iodine-based polarizer and an optical film, particularly a phase difference film, are laminated via an adhesive layer, is incorporated into an image display device and exposed to high temperature and high humidity, the iodine in the iodine-based polarizer penetrates the adhesive layer and the optical film, particularly the phase difference film, either alone or via water, and eventually reaches, for example, the panel or sensor of the image display device beyond the optical film, particularly the phase difference film, causing corrosion of these components. As a result, the panel or sensor of the image display device deteriorates, or the image display function is significantly impaired. However, in the laminated optical film according to the present invention, the adhesive layer interposed between the iodine-based polarizer and the optical film, particularly the phase difference film, is formed from a cured layer of an adhesive composition containing a specific proportion of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, thus exhibiting a barrier function that significantly inhibits the movement of iodine. Therefore, iodine has difficulty penetrating the adhesive layer and does not reach the panel or sensor of the image display device. As a result, even when an image display device incorporating the laminated optical film according to the present invention is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device by iodine can be sufficiently prevented.

[0023] As described above, in the laminated optical film according to the present invention, the adhesive layer interposed between the iodine-based polarizer and the optical film, particularly the phase difference film, exhibits a barrier function against iodine. Therefore, even if the optical film is a liquid crystal phase difference film, and even if the phase difference film is thin, it is possible to prevent iodine from penetrating the phase difference film in the first place, thereby effectively preventing corrosion of the panel or sensor of the image display device. This barrier function is effectively exhibited even when the adhesive layer is formed thinly.

[0024] In image display devices, if a thin iodine-based polarizer is used in a laminated optical film comprising at least an iodine-based polarizer and an optical film, particularly a phase difference film, then when the image display device is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device due to iodine may occur more significantly. However, in image display devices incorporating the laminated optical film according to the present invention, even when used under high temperature and high humidity conditions, the adhesive layer of the laminated optical film exhibits a barrier function that significantly inhibits iodine migration, thereby sufficiently preventing corrosion of the panel or sensor of the image display device due to iodine.

[0025] Furthermore, in the laminated optical film according to the present invention, when the adhesive layer is formed by a cured layer of an adhesive composition containing (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule and (meth)acrylate (B) containing a hydroxyl group, both the barrier function of the adhesive layer and the adhesion function of the adhesive layer to the iodine-based polarizer and optical film, particularly the phase difference film, can be achieved simultaneously, which is preferable because it can more effectively prevent corrosion of the panel or sensor of the image display device. However, from the viewpoint of more preferably solving the problem, it is preferable to control the content of (meth)acrylate (A) relative to (meth)acrylate (B) within a specific range.

[0026] This figure shows an example of an image display device equipped with a laminated optical film according to the present invention.

[0027] FIG. 1 is a diagram showing an example of an image display device including a laminated optical film according to the present invention. The image display device A shown in FIG. 1 is an organic EL image display device including an organic light emitting diode panel 7, and includes a laminated optical film 10 in which an iodine-based polarizer 1 and an optical film 2 are laminated via an adhesive layer 3. The optical film 2 is preferably a retardation film. However, the optical film may be, for example, a retardation film provided with an easy adhesion layer on the adhesive layer side, a retardation film subjected to a surface modification treatment such as corona treatment on the adhesive layer side, or an acrylic film, a polycarbonate film, a triacetyl cellulose (TAC) film, a cycloolefin polymer film, etc. laminated on the adhesive layer side of the retardation film. In the present invention, the laminated optical film may be composed of three or more optical films as long as it includes at least an iodine-based polarizer 1 → an adhesive layer 3 → an optical film (retardation film) 2 from the outer surface (visible side surface) toward the inner surface. In the embodiment shown in FIG. 1, the image display device A includes, in order from the outermost surface toward the organic light emitting diode panel 7, a transparent protective film 6 → a second adhesive layer 5 → an iodine-based polarizer 1 → an adhesive layer 3 → an optical film (retardation film) 2 → an adhesive layer 4 → an organic light emitting diode panel 7. As described above, even when the laminated optical film 10 according to the present invention is exposed to high temperature and high humidity, iodine contained in the iodine-based polarizer remains in the adhesive layer 3 due to the barrier function of the adhesive layer 3, thereby inhibiting the intrusion of iodine into the optical film (retardation film) 2, the adhesive layer 4, and further the organic light emitting diode panel 7 or a touch sensor (not shown), and sufficiently preventing the corrosion of the panel or sensor included in the image display device.

[0028] Hereinafter, each component of the laminated optical film according to the present invention will be described. The laminated optical film according to the present invention has at least an iodine-based polarizer and an optical film, particularly a retardation film, laminated via an adhesive layer.

[0029] <Iodine-based polarizer> In the present invention, the iodine-based polarizer is not particularly limited, and various types can be used. Examples of the iodine-based polarizer include those obtained by adsorbing iodine to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, and then uniaxially stretching it. The thickness of the polarizer is, for example, 3 to 20 μm.

[0030] However, in the present invention, from the viewpoint of improving the heating durability in a harsh environment 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 iodine-based polarizer. Particularly, it is preferably 12 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. Such a thin polarizer has less thickness unevenness, excellent visibility, and less dimensional change, so it has excellent durability against thermal shock.

[0031] An iodine-based polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by immersing the polyvinyl alcohol in an aqueous solution of iodine for dyeing and stretching it to 3 to 7 times its original length. It may contain boric acid, zinc sulfate, zinc chloride, etc. as required, or it can be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. By washing the polyvinyl alcohol-based film, not only can the dirt on the surface of the polyvinyl alcohol-based film and the blocking inhibitor be washed away, but also the unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based film. The stretching may be performed after dyeing with iodine, during dyeing, or after stretching and then dyeing with iodine. Stretching can also be performed in an aqueous solution or a water bath containing boric acid, potassium iodide, etc.

[0032] Examples of thin iodine-based polarizers include thin polarizers described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014 / 077599, International Publication No. 2014 / 077636, etc., or thin polarizers obtained from the manufacturing methods described therein.

[0033] 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.

[0034] The adhesive layer side of the iodine-based polarizer may be subjected to surface modification treatment before the adhesive layer is formed. 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 manufacture a laminated optical film with excellent appearance characteristics.

[0035] Furthermore, the adhesive layer side of the polarizer may be coated with an easy-adhesion composition before the adhesive layer is formed to create an easy-adhesion layer. Examples of easy-adhesion compositions include aqueous solutions containing a monofunctional radical polymerizable compound represented by general formula (1), which will be described later, and which can also be incorporated into the adhesive composition.

[0036] In the laminated optical film according to the present invention, the optical film laminated with the iodine-based polarizer is preferably a phase difference film. However, the optical film may be a phase difference film having an easy-adhesion layer on the adhesive layer side, or a phase difference film having a surface modification treatment such as corona treatment on the adhesive layer side. The easy-adhesion layer and surface modification treatment may be the same as those applied to the polarizer. Alternatively, the phase difference film may have an acrylic film, polycarbonate film, triacetylcellulose (TAC) film, cycloolefin polymer film, etc., laminated on the adhesive layer side. The phase difference film will be described below.

[0037] <Phase difference films> 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. The thickness of the film constituting the phase difference film is not particularly limited, but it is generally around 1 to 150 μm.

[0038] As for the phase difference film, the following formulas (1) to (3): 0.70 < Re

[450] / Re

[550] < 0.97 ... (1) 1.5 × 10 －３ <Δn < 6 × 10 －３ ... (2) 1.13 < NZ < 1.50 ... (3) (wherein Re

[450] and Re

[550] are the in-plane phase difference values ​​of the phase difference film measured with light of wavelengths of 450 nm and 550 nm at 23°C, respectively; Δn is the in-plane birefringence nx-ny when the refractive indices in the slow phase axis direction and the fast phase 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) an inverse wavelength-dispersive type phase difference film that satisfies this condition may also be used.

[0039] 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. However, as described above, even when the laminated optical film according to the present invention is exposed to high temperature and high humidity, the iodine contained in the iodine-based polarizer remains in the polarizer due to the barrier function of the adhesive layer. Therefore, even a thin liquid crystal phase difference film can sufficiently prevent corrosion of the panel or sensor of the image display device. When forming a liquid crystal phase difference film, a liquid crystalline compound is preferably used, and a solvent containing the liquid crystalline compound can be applied to the substrate using, for example, a wire bar, gap coater, comma coater, gravure coater, slot die, etc. In this case, the applied liquid crystalline solution may be air-dried or heat-dried. It is preferable that the liquid crystalline solution be applied at a concentration lower than the isotropic phase-liquid crystal phase transition concentration, i.e., in an isotropic phase state. In this case, it can be stably oriented by methods such as rubbing treatment or photo-alignment.

[0040] <Adhesive Layer> The adhesive layer of the laminated optical film according to the present invention is a cured layer of an adhesive composition containing at least a (meth)acrylate compound and a photopolymerization initiator. As described below, the adhesive layer of the laminated optical film according to the present invention has excellent barrier function in retaining the movement of iodine from iodine-based polarizers within the adhesive layer, making it possible to reduce its thickness. From the viewpoint of thinning the laminated optical film, the thickness of the adhesive layer is preferably 3 μm or less.

[0041] The adhesive composition used in the present invention contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of (meth)acrylate compound is 100 parts by mass. The adhesive composition used in the present invention is preferably a radical polymerizable adhesive composition using a photopolymerization initiator. Specifically, it is preferably a radical polymerizable adhesive composition capable of forming an adhesive layer by photo-radical polymerization of the (meth)acrylate compound using a photopolymerization initiator.

[0042] The (meth)acrylate (A) having a cyclic hydrocarbon skeleton is, for example, a (meth)acrylate having an alicyclic skeleton, and due to having a cyclic hydrocarbon skeleton, it can form an adhesive layer with low mobility and low ion permeability. Therefore, the movement of iodine from the iodine-based polarizer can be retained within the polarizer. As a result, even when an image display device incorporating the laminated optical film according to the present invention is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device by iodine can be sufficiently prevented. The (meth)acrylate (A) is preferably a compound having 5 to 12 carbon atoms constituting the cyclic hydrocarbon skeleton in the molecule, because it can more reliably retain the movement of iodine from the iodine-based polarizer within the adhesive layer.

[0043] In the present invention, it is preferable to use a (meth)acrylate (A) having a cyclic hydrocarbon skeleton that has at least two functionalities, because it can more reliably retain the movement of iodine from the iodine-based polarizer within the adhesive. Examples of two- or more functional (meth)acrylates include the compound described in formula (A1) below, which will be described later.

[0044] In the present invention, the (meth)acrylate (A) having a cyclic hydrocarbon skeleton is defined as the following formulas (A1) to (A5); It is preferable to use at least one compound selected from the group consisting of the compounds described in [reference] because it can more reliably retain the movement of iodine from the iodine-based polarizer within the adhesive layer.

[0045] From the viewpoint of providing a barrier function against iodine in the adhesive layer, the adhesive composition used in the present invention contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of (meth)acrylate compounds is 100 parts by mass. More preferably, it is 80 parts by mass or more, and even more preferably 85 parts by mass or more.

[0046] The adhesive composition used in the present invention preferably further contains (meth)acrylate (B) containing a hydroxyl group. (Meth)acrylate (B) containing a hydroxyl group has the effect of enhancing the adhesion function of the adhesive layer to iodine-based polarizers and optical films, particularly phase difference films. For this reason, when the laminated optical film according to the present invention has an adhesive layer formed by a cured layer of an adhesive composition containing (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule and (meth)acrylate (B) containing a hydroxyl group, it is preferable that both the barrier function of the adhesive layer and the adhesion function of the adhesive layer to iodine-based polarizers and optical films, particularly phase difference films, can be achieved. However, in order to achieve both the barrier function of the adhesive layer and the adhesion function of the adhesive layer to iodine-based polarizers and optical films, particularly phase difference films, it is preferable that when the total amount of (meth)acrylate compounds in the adhesive composition is 100 parts by mass, the amount of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule is 70 parts by mass or more, and furthermore, the content of (meth)acrylate (A) relative to (meth)acrylate (B) is designed to be within the range of 2 to 6 times. To further effectively achieve both the barrier function of the adhesive layer and the adhesion function of the adhesive layer to iodine-based polarizers and optical films, particularly phase difference films, it is even more preferable that when the total amount of (meth)acrylate compounds is 100 parts by mass, the amount of (meth)acrylate (B) is 5 to 25 parts by mass.

[0047] Examples of hydroxyl group-containing (meth)acrylates (B) include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; and N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-methylol-N-propane (meth)acrylamide.

[0048] In addition to (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule and (meth)acrylate (B) containing a hydroxyl group, the adhesive composition used in the present invention may also contain active energy ray curable polymerizable compounds such as electron beam curable, ultraviolet curable, and visible light curable compounds. Active energy ray curable polymerizable compounds can be classified into radical polymerizable compounds and cationic polymerizable compounds. 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.

[0049] Radical polymerizable compounds include compounds having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acrylic group or a vinyl group. These monomer components can be either monofunctional radical polymerizable compounds or polyfunctional radical polymerizable compounds having two or more polymerizable functional groups. Furthermore, these radical polymerizable compounds can be used individually or in combination of two or more. Among these radical polymerizable compounds, compounds having a (meth)acrylic group are preferred, for example.

[0050] Examples of monofunctional radical polymerizable compounds include (meth)acrylic acid derivatives. Examples of (meth)acrylic acid derivatives include 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, alkylphenoxy polyethylene glycol (meth)acrylate; cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl acrylate, and cyclopentyl Examples include cycloalkyl (meth)acrylates such as (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; polycyclic (meth)acrylates such as 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-ylmethyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and others.

[0051] Other 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, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0052] Other monofunctional radical polymerizable compounds include, for example, (meth)acrylamide derivatives having a (meth)acrylamide group. Specific examples of (meth)acrylamide derivatives include, for example, N-alkyl group-containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl(meth)acrylamide and aminoethyl(meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; and N-mercaptoalkyl group-containing (meth)acrylamide derivatives such as mercaptomethyl(meth)acrylamide and mercaptoethyl(meth)acrylamide. Furthermore, examples of heterocyclic (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.

[0053] Furthermore, monofunctional radical polymerizable compounds include epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; halogen-containing (meth)acrylates such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; and dimethylaminoethyl (meth)acrylate, etc. Alkylaminoalkyl (meth)acrylates; oxetane group-containing (meth)acrylates such as 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; or hydroxypivalate neopentyl glycol (meth)acrylic acid adducts, p-phenylphenol (meth)acrylate, etc. may be used.

[0054] Furthermore, as monofunctional radical polymerizable compounds, carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid may be used.

[0055] Furthermore, as monofunctional radical polymerizable compounds, for example, 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 may be used.

[0056] Furthermore, as the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group may 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.

[0057] Furthermore, in the present invention, the adhesive composition contains the following general formula (1): A monofunctional radical polymerizable 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 Each of these may independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have substituents, an aryl group, or a heterocyclic group.

[0058] In the monofunctional radical polymerizable compound represented by general formula (1), the aliphatic hydrocarbon group may be a linear or branched alkyl group having 1 to 20 substituents, a cyclic alkyl group having 3 to 20 substituents, or an alkenyl group having 2 to 20 substituents. The aryl group may be a phenyl group having 6 to 20 substituents, or a naphthyl group having 10 to 20 substituents. The heterocyclic group may be a 5-membered or 6-membered ring containing at least one heteroatom, which may have substituents. These may be linked to each other 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.

[0059] X in the monofunctional radical polymerizable compound represented by general formula (1) is a reactive group, a functional group that can react with the curable component constituting the adhesive layer, and examples include hydroxyl group, amino group, aldehyde group, carboxyl group, vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, α,β-unsaturated carbonyl group, mercapto group, halogen group, etc. When the curable adhesive composition constituting 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 adhesive composition constituting 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 monofunctional radical polymerizable 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 adhesive layer. Furthermore, it is also preferable because the (meth)acrylamide group has high polarity and excellent adhesive properties, which allows the effects of the present invention to be obtained efficiently. When the curable adhesive composition constituting 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. In particular, the presence of an epoxy group is preferred because it provides excellent adhesion between the resulting adhesive layer and the adherend, and the presence of a vinyl ether group is preferred because it provides excellent curability of the curable adhesive composition.

[0060] Preferred specific examples of monofunctional radical polymerizable 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.

[0061] Examples of monofunctional radical polymerizable compounds represented by general formula (1) include, in addition to the examples given above, esters of (meth)acrylates and boric acid, such as esters of hydroxyethyl acrylamide and boric acid, methylol acrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

[0062] Examples of polyfunctional radical polymerizable compounds having two or more polymerizable functional groups include tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, and Examples include esters of (meth)acrylic acid with polyhydric alcohols such as opentyl glycol di(meth)acrylate, tricyclodecanedimethanol 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 Light Acrylate 9EG-A (manufactured by Kyoeisha Chemical Co., Ltd.), 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), CD-536 (manufactured by Sartomer), and others.

[0063] In the present invention, the adhesive composition that serves as the raw material for the adhesive layer of the laminated optical film may contain, in addition to radical polymerizable compounds, an acrylic oligomer obtained by polymerizing (meth)acrylic monomers and which does not have polymerizable groups. By including the acrylic oligomer in the adhesive composition, curing shrinkage when the composition is irradiated and cured with active energy rays can be reduced, and the interfacial stress between the adhesive layer and the adherends such as polarizers and optical films can be reduced. As a result, a decrease in the adhesion between the adhesive layer and the adherend can be suppressed.

[0064] For active energy ray curing adhesives, low viscosity is preferable when considering workability and uniformity during coating. Therefore, acrylic oligomers formed by polymerizing (meth)acrylic monomers and not having polymerizable groups are also preferably low viscosity. As acrylic oligomers that are low viscosity and can prevent curing shrinkage of the adhesive layer, those with a weight-average molecular weight (Mw) of 15,000 or less are preferable, those with a weight-average molecular weight (Mw) of 10,000 or less are preferable, and those with a weight-average molecular weight (Mw) of 5,000 or less are particularly preferable. On the other hand, in order to sufficiently suppress curing shrinkage of the cured product 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, 2,2-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 other alkyl (meth)acrylic acid (C1-20) esters, as well as, 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-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.

[0065] When using radical polymerizable compounds, 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 cleaves with ultraviolet or visible light is used. Examples of such 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-morpholinopropan-1-one; and benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. 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.

[0066] The amount of the photopolymerization initiator is 20% by weight or less when the total amount of the adhesive composition is considered to be 100% by weight. Preferably, the amount of the photopolymerization initiator is 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and more preferably 0.1 to 5% by weight.

[0067] Also, when the adhesive composition is used as a visible light-curable type containing a radically polymerizable compound as a curable component, 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.

[0068] As the photoinitiator, a compound represented by the following general formula (2);

[0069] (In the formula, R １ and R ２ represent -H, -CH ２ CH ３ , -iPr or Cl, and R １ and R ２ may be the same or different) is used alone, or it is preferable to use the compound represented by the general formula (2) in combination with a photoinitiator that is highly sensitive to light of 380 nm or more described later. When the compound represented by the general formula (2) is used, the adhesiveness is superior compared to the case where a photoinitiator that is highly sensitive to light of 380 nm or more is used alone. Among the compounds represented by the general formula (2), diethylthioxanthone in which R １ and R ２ are -CH ２ CH ３ is particularly preferable. The composition ratio of the compound represented by the general formula (2) in the adhesive composition is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and even more preferably 0.9 to 3 parts by weight with respect to 100 parts by weight of the total amount of the curable components.

[0070] 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 a polymerization initiation aid, the addition amount is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight with respect to 100 parts by weight of the total amount of the curable components.

[0071] Furthermore, known photopolymerization initiators can be used in combination as needed. Since the transparent protective film having UV absorption ability does 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.

[0072] In particular, as a photopolymerization initiator, in addition to the photopolymerization initiator of general formula (2), a compound represented by the following general formula (3);

[0073] (In the formula, R ３ , R ４ and R ５ H is -H, -CH ３ ien-CH ２ CH ３ , indicates -iPr or Cl, R ３ , R ４ and R ５It is preferable to use compounds that are the same or different. Suitable compounds represented by general formula (3) include commercially available 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (trade name: Omnirad 819, manufacturer: IGM Resins B.V.) and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (trade name: Omnirad 907, manufacturer: IGM Resins B.V.). In addition, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name: Omnirad 369, manufacturer: IGM Resins B.V.) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (trade name: Omnirad 379, manufacturer: IGM Resins B.V.) are preferred due to their high sensitivity.

[0074] In the present invention, it is preferable to use a hydroxyl group-containing photopolymerization initiator among the above-mentioned photopolymerization initiators. When the active energy ray-curable adhesive composition contains a hydroxyl group-containing photopolymerization initiator as a polymerization initiator, the solubility in the adhesive layer with a high concentration of component A on the polarizer side increases, and the curability of the adhesive layer increases. Examples of photopolymerization initiators having a hydroxyl group include 2-methyl-2-hydroxypropiophenone (trade name "DAROCUR 1173", manufactured by BASF), 1-hydroxycyclohexylphenyl ketone (trade name "IRGACURE 184", manufactured by BASF), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name "IRGACURE 2959", manufactured by BASF), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one (trade name "IRGACURE 127", manufactured by BASF). 1-hydroxycyclohexylphenyl ketone is particularly preferred because of its excellent solubility in adhesive layers with a high concentration of component A.

[0075] In addition to (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule and (meth)acrylate (B) containing a hydroxyl group, the adhesive composition used in the present invention may also contain cationic polymerizable compounds. Cationic polymerizable compounds are classified into monofunctional cationic polymerizable compounds having one cationic polymerizable functional group in its molecule and polyfunctional cationic polymerizable compounds having two or more cationic polymerizable functional groups in its molecule. Monofunctional cationic polymerizable compounds have relatively low liquid viscosity, so including them in the adhesive composition can reduce the liquid viscosity of the adhesive composition. Furthermore, monofunctional cationic polymerizable compounds often have functional groups that exhibit various functions, so including them in the adhesive composition can allow the cured product to exhibit various functions. Polyfunctional cationic polymerizable compounds can cause three-dimensional crosslinking of the cured product of the cationic polymerizable adhesive composition.

[0076] Cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Compounds containing epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. 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, and specifically, Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2083, Celoxide 2085 (all manufactured by Daicel Chemical Industries, Ltd.), and Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, R-6110 (all manufactured by Dow Chemical Japan Ltd.). Compounds containing an oxetanyl group have the effect of improving the curability of cationic polymerizable adhesive compositions and reducing the liquid viscosity of the composition, therefore, they contain It is preferable to include them. Examples of compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenol novolac oxetane. Aronoxetane OXT-101, Aronoxetane OXT-121, Aronoxetane OXT-211, Aronoxetane OXT-221, Aronoxetane OXT-212 (all manufactured by Toagosei Co., Ltd.) are commercially available. Compounds having a vinyl ether group are preferable to include because they have the effect of improving the curability of the cationic polymerizable adhesive composition and reducing the liquid viscosity of the composition.Compounds having a vinyl 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.

[0077] The laminated optical film according to the present invention has an iodine-based polarizer and an optical film, particularly a phase difference film, laminated with an adhesive layer in between. As shown in Figure 1, the laminated optical film according to the present invention may also have a transparent protective film laminated on the outer surface (visible surface) of the iodine-based polarizer via a second adhesive layer.

[0078] <Transparent Protective Film> 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, 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 appropriate 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.

[0079] 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 Those with a ferrous film content of 24 hours or less are particularly preferred, and 120 g / m² is preferred. ２ Those with a shelf life of 24 hours or less are even more preferable.

[0080] The transparent protective film may be provided with functional layers such as a hard coat layer, an anti-reflective layer, an anti-sticking layer, a diffusion layer, or an anti-glare layer. These functional layers, such as the hard coat layer, anti-reflective layer, anti-sticking layer, diffusion layer, and anti-glare layer, can be provided on the transparent protective film itself, or they can be provided separately from the transparent protective film.

[0081] 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.

[0082] <Second Adhesive Layer> The second adhesive layer may be formed by a cured layer of an adhesive composition containing 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of (meth)acrylate compounds for constituting the aforementioned adhesive layer is 100 parts by mass. Alternatively, it may be formed by a radical polymerizable adhesive composition, a cationic polymerizable adhesive composition, or an aqueous adhesive composition known to those skilled in the art. As the aqueous adhesive composition, an aqueous solution (for example, solid content concentration of 0.5 to 60% by weight) of an aqueous adhesive such as an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex adhesive, or an aqueous polyester adhesive is preferably used. From the viewpoint of thinning, the thickness of the second adhesive layer is preferably 0.1 to 5 μm.

[0083] The laminated optical film according to the present invention has an adhesive layer provided on the optical film, particularly on the phase difference film side, and is bonded to an organic light-emitting diode panel or a touch sensor.

[0084] <Adhesive Layer> The adhesive forming 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 adhesion properties, and have excellent weather resistance and heat resistance, such as acrylic adhesives, are preferably used.

[0085] 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, except for 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.

[0086] 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 at least an iodine-based polarizer and an optical film, particularly a phase difference film, are laminated via an adhesive layer, wherein the adhesive layer is a cured layer of an adhesive composition containing at least a (meth)acrylate compound and a photopolymerization initiator, the adhesive composition contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of the (meth)acrylate compound is 100 parts by mass, and the method comprises: a coating step of coating the adhesive composition onto at least one of the iodine-based polarizer and the optical film, particularly a phase difference film; a bonding step of bonding the iodine-based polarizer and the optical film, particularly a phase difference film, via an adhesive layer formed by irradiating at least the adhesive composition with active energy rays from the iodine-based polarizer side or the optical film, particularly a phase difference film side. The following describes each step.

[0087] (Coating Process) The method for coating an adhesive composition onto at least one of an iodine-based polarizer and an optical film, particularly a phase difference 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. The viscosity of the adhesive composition is preferably 0.5 to 100 mPa·s. If the viscosity of the composition is high, the surface smoothness after coating will be poor and an appearance defect will occur, which is undesirable. For this reason, each composition can be heated or cooled to adjust the viscosity to a preferred range before application.

[0088] (Lamination process) The iodine-based polarizer and optical film, particularly the phase difference film, are laminated together. When laminating the iodine-based polarizer and optical film, particularly the phase difference film, via an adhesive composition, a roll laminator or the like is used.

[0089] (Bonding process) The iodine-based polarizer and the optical film, particularly the phase difference film, are bonded together via an adhesive layer formed by irradiating the iodine-based polarizer or the optical film, particularly the phase difference film, with active energy rays from either side to cure at least the adhesive composition. The irradiation direction of the active energy rays (electron beam, ultraviolet light, visible light, etc.) can be any suitable direction.

[0090] When irradiating with an electron beam, any suitable irradiation conditions can be adopted, as long as they are conditions that can at least cure the adhesive composition. For example, the acceleration voltage for electron beam irradiation is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive, resulting in insufficient curing. If the acceleration voltage exceeds 300 kV, the penetrating force through the sample may be too strong, potentially damaging the iodine-based polarizer and optical film, especially the phase difference film. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the adhesive will not cure sufficiently. If it exceeds 100 kGy, it will damage the iodine-based polarizer and optical film, especially the phase difference film, causing a decrease in mechanical strength and yellowing, making it impossible to obtain the desired optical properties.

[0091] 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 iodine-based polarizer and optical film, especially the phase difference film, introducing oxygen appropriately can intentionally cause oxygen inhibition on the surface of the iodine-based polarizer and optical film, especially the phase difference film, which are initially struck by the electron beam. This prevents damage to the iodine-based polarizer and optical film, especially the phase difference film, and allows the electron beam to be efficiently directed only at the adhesive.

[0092] 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 particularly, an active energy ray that has the highest irradiation amount of visible light in the wavelength range of 380 nm to 450 nm. When manufacturing the laminated optical film according to the present invention, it is preferable to use a gallium-filled metal halide lamp or an LED light source that emits light in the wavelength range of 380 to 440 nm as the active energy ray. Alternatively, a light source containing ultraviolet and visible light such as a low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, incandescent bulb, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser, or sunlight can be used, and it is also possible to use a bandpass filter to block ultraviolet light with wavelengths shorter than 380 nm. To improve the adhesion performance of the adhesive layer between the iodine-based polarizer and the optical film, particularly the phase difference 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.

[0093] When manufacturing the laminated optical film according to the present invention on a continuous line, the line speed depends on the curing time of the adhesive composition, 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 iodine-based polarizer and optical film, especially the phase difference film, 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 will be insufficient, and the desired adhesion may not be obtained.

[0094] (Laminated Optical Film) The laminated optical film according to the present invention can be preferably used for forming various image display devices such as organic EL display devices and liquid crystal display devices. The formation of organic EL display devices and 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 optical films, and lighting systems as needed, and incorporating drive circuits, but the present invention is not particularly limited except for the use of the laminated optical film according to the present invention, and can be carried out in accordance with conventional methods. Any type of liquid crystal cell can be used, for example, TN type, STN type, or π type.

[0095] 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.

[0096] The following describes some embodiments of the present invention, but the embodiments of the present invention are not limited to these.

[0097] <Iodine-based polarizer> A laminate in which a 9 μm thick PVA layer was formed on an amorphous PET substrate was stretched by air-assisted stretching at a stretching temperature of 130°C to produce a stretched laminate. Next, a colored laminate was produced by dyeing the stretched laminate, and then an optical film laminate containing a 5 μm thick PVA layer was produced by stretching the colored laminate in boric acid water at a stretching temperature of 65°C, so that the total stretching ratio was 5.94 times, integrally with the amorphous PET substrate. Through this two-stage stretching, an optical film laminate containing a 5 μm thick PVA layer (iodine-based polarizer) was obtained, in which the PVA molecules of the PVA layer formed on the amorphous PET substrate were highly oriented, and the iodine adsorbed by dyeing was highly oriented in one direction as a polyiodide ion complex, constituting a thin polarizer.

[0098] <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 (BYK-360, Bic Chemie) and a photopolymerization initiator (Omnirad 907, IGM Resins) were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and photopolymerization 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.

[0099] <Phase Difference Film> Using a biaxially oriented norbornene-based film (Zeonor Film, manufactured by Nippon Zeon, 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 / 2, and the film was heated at 100°C for 3 minutes to orient the liquid crystals. 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 (a liquid crystal phase difference film) was provided by photocuring by irradiation with ultraviolet light.

[0100] <Laminated Optical Film> The PVA layer surface of an optical film laminate containing a PVA layer (iodine-based polarizer) is treated with a corona treatment machine at a treatment density of 50 W・min / m ２ Corona treatment was performed on the corona-treated surface. The adhesive compositions used in Examples 1 to 7 and Comparative Example 1 were coated to a coating thickness of 2 μm using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, opening ratio of cells formed on the gravure roll: 40%, rotation speed 140% / line speed) (coating process). The coating thickness was measured using a spectroscopic interferometry film thickness meter (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995").

[0101] The materials constituting the adhesive compositions used in Examples 1 to 7 and Comparative Example 1 are as follows: ((Meth)acrylate (A)) ・Tricyclodecanedimethanol diacrylate: trade name "DCP-A", manufactured by Kyoeisha Chemical Co., Ltd., (compound listed in (A1)) ・Isobornyl acrylate: trade name "IB-XA", manufactured by Osaka Organic Chemical Industry Co., Ltd., (compound listed in (A2)) ・Dicyclopentenyl acrylate: trade name "FA511-AS", manufactured by Resonac Co., Ltd., (compound listed in (A3)) ・2-methyl-2-adamantyl acrylate: trade name "MADA", manufactured by Osaka Organic Chemical Industry Co., Ltd., (compound listed in (A4)) ((Meth)acrylate (B)) ・4-Hydroxybutyl acrylate: trade name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd. ・2-Hydroxyethyl acrylamide: trade name "HEAA", manufactured by KJ Chemicals Co., Ltd. ((Meth)acrylate (B)) • 4-Hydroxybutyl acrylate: Trade name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd. • 2-Hydroxyethyl acrylamide: Trade name "HEAA", manufactured by KJ Chemicals Co., Ltd. (Initiator) • Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide: Trade name "Omnirad 819", manufactured by IGM Resins B.V. • 1-Hydroxycyclohexyl-phenyl ketone: Trade name "Omnirad 184", manufactured by IGM Resins B.V. • 2,4-Diethylthioxanthone: Trade name "DETX-S", manufactured by Nippon Kayaku Co., Ltd.

[0102] The adhesive composition coating surface of the PVA layer (iodine-based polarizer) of an optical film laminate was treated with a corona treatment machine at a treatment density of 50 W・min / m². ２ The homogeneous oriented liquid crystal layer (liquid crystal phase difference film) surface of the 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 process). The bonding line speed was 15 m / min. Subsequently, a visible light irradiation device (Heraeus Light HAMMER 10 Mark III, bulb: V-bulb, peak illuminance: 1600 mW / cm²) was used from the phase difference film side. ２ Total irradiation dose: 1000 / mJ / cm² ２The irradiance and cumulative irradiation dose of the active energy rays were measured using a Power Puck 2 (manufactured by EIT, UVV measurement). The adhesive compositions used in Examples 1-7 and Comparative Example 1 were cured by irradiating them with active energy rays, thereby producing a laminated optical film in which a PVA layer (iodine-based polarizer) of an optical film laminate and a phase difference film were laminated via an adhesive layer (cured layer of the adhesive composition used in Examples 1-7 or Comparative Example 1). The thickness of the adhesive layer (cured layer of the adhesive composition used in Examples 1-7 or Comparative Example 1) was 1.9 μm. After the bonding process, the substrate (biaxially oriented norbornene-based film) was peeled off from the phase difference film.

[0103] The adhesion and iodine barrier properties in the adhesive layer of the laminated optical films produced in Examples 1 to 7 and Comparative Example 1 were evaluated by the following methods.

[0104] (Adhesion of Laminated Optical Film) The amorphous PET substrate of the laminated optical film manufactured above was peeled off, and double-sided tape (No. 500, manufactured by Nitto Denko Corporation) was attached to the peeled surface (iodine-based polarizer surface). Furthermore, adhesive tape (No. 360, manufactured by Nitto Denko Corporation) was attached to the phase difference film side for reinforcement, and then the film was cut to a size of 200 mm in the direction perpendicular to the stretching direction of the iodine-based polarizer and 15 mm in the direction parallel to it. After making an incision between the iodine-based polarizer and the phase difference film with a utility knife, the release film of the double-sided tape was peeled off, and the adhesive side was attached to a glass plate. Next, the thin polarizer and transparent protective film were peeled off at a peeling speed of 20,000 mm / min in the 90-degree direction using an angle-adjustable adhesive / film peeling analyzer (VPA-2, manufactured by Kyowa Interface Chemical Co., Ltd.), and the peeling strength (N / 15 mm) was measured.

[0105] (Iodine barrier properties in the adhesive layer of a laminated optical film) In order to laminate an adhesive layer on the phase difference film side of the laminated optical film manufactured above, the adhesive layer was manufactured by the following method.

[0106] <Adhesive Layer> A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile was added to 100 parts by weight of the monomer mixture (solids) as a polymerization initiator along with ethyl acetate. After introducing nitrogen gas and purging with nitrogen while gently stirring, the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55°C. Subsequently, ethyl acetate was added to the resulting reaction solution to prepare a solution of (meth)acrylic polymer A1 with a weight-average molecular weight of 1.6 million, with a solids content concentration of 30%. An acrylic adhesive composition was prepared by blending 0.1 parts by weight of an isocyanate crosslinking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.), 0.3 parts by weight of a peroxide crosslinking agent, benzoyl peroxide (trade name: Niper BMT, manufactured by Nippon Oil & Fats Co., Ltd.), and 0.08 parts by weight of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts by weight of the solid content of the obtained (meth)acrylic polymer A1 solution. The acrylic adhesive composition was uniformly coated onto the surface of a 38 μm thick polyethylene terephthalate film (release liner) treated with a silicone release agent using a fountain coater, and dried in a 155°C air-circulating constant temperature oven for 2 minutes to form a 20 μm thick adhesive layer on the surface of the release liner.

[0107] The adhesive-coated release liner prepared above was transferred to the phase difference film side of the laminated optical film, and then the release liner was peeled off. Next, an evaluation sample was prepared by bonding the adhesive layer side of the laminated optical film to an alkali-free glass with a thickness of 0.7 mm and an aluminum vapor-deposited film attached. Using this evaluation sample, a corrosion test was conducted by exposing it to an environment of 60°C and 95% humidity for 240 hours. The presence or absence of corrosion was confirmed visually, and if light leakage occurred in the aluminum vapor-deposited film due to iodine penetrating from the iodine-based polarizer of the laminated optical film, it was determined that corrosion was present.

[0108]

[0109] The results in Table 1 show that the laminated optical films according to Examples 1 to 7 exhibit excellent adhesion between the iodine-based polarizer and the phase difference film, and the barrier function of the adhesive layer against iodine is fully exercised, thus effectively preventing corrosion of the panel or sensor of the image display device even when used under high temperature and high humidity conditions. On the other hand, the laminated optical film according to Comparative Example 1 exhibits excellent adhesion between the iodine-based polarizer and the phase difference film, but its barrier function against iodine is inferior, and therefore it cannot prevent corrosion of the panel or sensor of the image display device when used under high temperature and high humidity conditions.

[0110] A. Image display device, 1. Iodine-based polarizer, 2. Optical film (phase difference film), 3. Adhesive layer, 4. Adhesive layer, 5. Second adhesive layer, 6. Transparent protective film, 7. Organic light-emitting diode panel, 10. Laminated optical film

Claims

1. A laminated optical film comprising at least an iodine-based polarizer and an optical film laminated via an adhesive layer, wherein the adhesive layer is a cured layer of an adhesive composition containing at least a (meth)acrylate compound and a photopolymerization initiator, and the adhesive composition contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of the (meth)acrylate compound is 100 parts by mass.

2. The laminated optical film according to claim 1, wherein the optical film is a phase difference film.

3. The laminated optical film according to claim 2, wherein the phase difference film is a liquid crystal phase difference film.

4. The laminated optical film according to claim 2, wherein the thickness of the phase difference film is 5 μm or less.

5. The laminated optical film according to any one of claims 1 to 4, wherein the thickness of the adhesive layer is 3 μm or less.

6. The laminated optical film according to any one of claims 1 to 5, wherein the thickness of the iodine-based polarizer is 8 μm or less.

7. The laminated optical film according to any one of claims 1 to 6, wherein the (meth)acrylate (A) is a compound having 5 to 12 carbon atoms that constitute a cyclic hydrocarbon skeleton within the molecule.

8. The laminated optical film according to any one of claims 1 to 7, wherein the (meth)acrylate (A) is at least a bifunctional (meth)acrylate.

9. The (meth)acrylate (A) is represented by the following formulas (A1) to (A5); A laminated optical film according to any one of claims 1 to 8, wherein the compound is at least one compound selected from the group consisting of the compounds described above.

10. The laminated optical film according to any one of claims 1 to 9, wherein the adhesive composition further contains a (meth)acrylate (B) containing a hydroxyl group.

11. The laminated optical film according to claim 10, wherein the content of (meth)acrylate (A) relative to (meth)acrylate (B) is in the range of 2 to 6 times.

12. The laminated optical film according to claim 10, wherein the adhesive composition contains 5 to 25 parts by mass of the (meth)acrylate (B) when the total amount of the (meth)acrylate compound is 100 parts by mass.

13. An image display device comprising a laminated optical film according to any one of claims 1 to 12.

14. An organic EL display device comprising a laminated optical film according to any one of claims 1 to 12.

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