Laminate optical film and image display device

Abstract

To provide a laminate optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated, and in which an adhesive layer for laminating both films is made thin and display unevenness due to the adhesive layer is reduced.SOLUTION: A laminate optical film is configured such that at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, where the molecular adhesive layer is a cured material layer of a molecular adhesive having at least one reactive group selected from a group consisting of a silanol group and an alkoxysilyl group, and when the laminate smoothness of the entire laminate optical film is β, β<0.45 arcmin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer. The laminated optical film can be used alone or in combination with a polarizing film to form an image display device such as a liquid crystal display device (LCD), an organic electroluminescence display device, a CRT, or a PDP. [Background technology]

[0002] Generally, image display devices such as liquid crystal display devices and organic electroluminescence display devices are equipped with laminated optical films. Image display devices are expected to be used in various environments, but when used in environments with high heat and humidity, display unevenness caused by dimensional changes is an issue. Display unevenness is not only caused by dimensional changes, but also by the influence of surface irregularities of the adhesive on the laminated optical film laminated with an adhesive. Furthermore, although laminated optical films have become thinner in recent years, there has been an issue in that it is difficult to ensure adhesion between optical films when they are bonded in thin layers.

[0003] Incidentally, the following Patent Document 1 describes a technology for providing a polarizing plate that suppresses poor appearance due to thermal shrinkage of a polyvinyl alcohol-based polarizing film and has excellent durability, in which the polarizing plate comprises a polarizing film made of a polyvinyl alcohol-based resin and a light-transmitting supporting substrate laminated on at least one side of the polarizing film via an adhesive layer, the adhesive layer being formed from a molecular adhesive that chemically bonds the polarizing film and the supporting substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2022 / 172755 publication Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in the above Patent Document 1 aims to suppress appearance defects caused by thermal shrinkage of a polyvinyl alcohol-based polarizing film, but makes no mention of suppressing display unevenness in a laminated optical film that includes at least a retardation film.

[0006] The present invention has been developed in view of the above-mentioned circumstances, and aims to provide a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated together, in which the adhesive layer for laminating the two is made thin while display unevenness caused by the adhesive layer is reduced.

[0007] A further object of the present invention is to provide an image display device using the laminated optical film. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the inventors have found that when laminating a retardation film and an optical film other than a polyvinyl alcohol film, the two films are laminated together using a molecular adhesive layer, which is a cured layer of a specific molecular adhesive, and the laminate smoothness of the laminated optical film can be controlled, thereby achieving the above object, and have solved the present invention.

[0009] That is, the present invention provides a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, the molecular adhesive layer being a cured layer of a molecular adhesive having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group, and when the laminate smoothness of the entire laminated optical film is β, β<0.45arcmin The present invention relates to a laminated optical film (1), characterized in that:

[0010] In the above-mentioned laminated optical film (1), the optical film is preferably a laminated optical film (2) which is a retardation film.

[0011] In the above laminated optical film (1) or (2), a laminated optical film (3) is preferred in which the molecular adhesive layer has a thickness of 1 nm or more and 100 nm or less.

[0012] In any one of the laminated optical films (1) to (3), a laminated optical film (4) in which the thickness of the retardation film is 5 μm or less is preferred.

[0013] In any one of the laminated optical films (1) to (4), a laminated optical film (5) is preferred in which the molecular adhesive is a compound having a first reactive group RG1 and a second reactive group RG2, the first reactive group RG1 being at least one reactive group selected from the group consisting of an azide group, an amino group, an epoxy group, and an acryloyl group, and the second reactive group RG2 being at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group.

[0014] In any one of the laminated optical films (1) to (5), the molecular adhesive is represented by the following general formula (1): GE (1) (In the general formula (1), E is Si(R') n (OA) 3-n When a plurality of R's are present, each independently represents a chain hydrocarbon group having 1 to 4 carbon atoms. When a plurality of A's are present, each independently represents a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms. n represents an integer of 0 to 2. G represents a triazine ring C or an alkyl group D. Triazine ring C is Q 1 Q 2 in the side chain, and Q 1 and Q 2 are each independently N3 or -NR 1 (R 2 ) stands for R 1 and R 2each independently represents a hydrogen atom, a hydrocarbon group having 1 to 24 carbon atoms, an aminoalkyl group, or -R-Si(R') n (OA) 3-n The alkyl group D is a hydrocarbon group having 1 to 24 carbon atoms. 3 and Q 3 represents an azide group, an amino group, an epoxy group, or an acryloyl group.) is preferred.

[0015] In any one of the laminated optical films (1) to (6), when the laminate smoothness of a film having a larger laminate smoothness arcmin value among the retardation film and the optical film is α, 0.93≦α / β≦1.05 It is preferable that the laminated optical film (7) satisfies the above.

[0016] Further, the present invention provides a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, and a polarizing film is further laminated on at least one of the laminated optical films, and when the laminate smoothness of the entire laminated optical film is β', β'<0.45arcmin The present invention relates to a laminated optical film (8),

[0017] In the above laminated optical film (8), a laminated optical film (9) is preferred in which the optical film is a retardation film.

[0018] In the laminated optical film (8) or (9), when the laminate smoothness of the film having a larger laminate smoothness arcmin value among the retardation film, the optical film, and the polarizing film is defined as α', 0.93≦α' / β'≦1.05 It is preferable that the laminated optical film (10) satisfies the above.

[0019] The present invention also relates to an image display device comprising the laminated optical film (1) or the laminated optical film (8). Effect of the Invention

[0020] The laminated optical film according to the present invention is a laminated film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer. Here, the retardation film constituting the laminated optical film is generally thin and has poor shape retention. For example, in the adhesive layer for laminating the retardation film, when unevenness occurs due to curing shrinkage or the like, the smoothness of the retardation film deteriorates due to this, and the laminated smoothness of the laminated optical film deteriorates, and when the laminated optical film is incorporated into an image display device, display unevenness may occur. However, the laminated optical film according to the present invention has a specific molecular adhesive layer for laminating the retardation film, specifically a molecular adhesive layer which is a cured layer of a molecular adhesive having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group, so that the smoothness of the retardation film is maintained, and when the laminated smoothness of the entire laminated optical film is β, it can be designed to be β<0.45 arcmin. For this reason, the laminated optical film according to the present invention can reduce display unevenness caused by the adhesive layer. In particular, in the present invention, when the laminated optical film is one in which two retardation films are laminated via a molecular adhesive layer, the smoothness of both retardation films can be maintained, and thus display unevenness caused by the adhesive layer can be further reduced, which is preferable.

[0021] In the present invention, in particular, when a compound having at least one reactive group selected from the group consisting of silanol group and alkoxysilyl group and containing a triazine ring, or an amino-based silane coupling agent, an epoxy-based silane coupling agent, or a mixture thereof is used as the molecular adhesive, the smoothness of the retardation film is maintained, and when the laminate smoothness of the entire laminated optical film is β, it is designed to be β<0.45 arcmin, so that the display unevenness of the laminated optical film can be further suppressed, which is preferable. The reason why such a remarkable effect is obtained is not clear, but it can be inferred as follows.

[0022] Compounds having at least one reactive group selected from the group consisting of silanol groups and alkoxysilyl groups and containing a triazine ring, or amino-based silane coupling agents, epoxy-based silane coupling agents, and mixtures thereof have reactive groups having up to three alkoxysilyl groups that can generate silanol groups by hydrolysis. Therefore, the adhesive forms chemical bonds with the optical film other than the retardation film and polyvinyl alcohol film, which are the adherends, and adheres them to each other. Here, when a conventional pressure-sensitive adhesive is used, the adherends are only in contact with each other by van der Waals forces, etc., so the adhesion is insufficient. In addition, when a conventional ultraviolet irradiation type adhesive is used, curing shrinkage occurs during curing, which causes unevenness on the adhesive surface, and the smoothness of the laminated optical film tends to deteriorate. On the other hand, compounds having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group and containing a triazine ring, or amino-based silane coupling agents, epoxy-based silane coupling agents, and mixtures thereof bond adherends together through chemical bonds, and therefore have high adhesion and are less likely to undergo cure shrinkage. This makes it possible to suppress the occurrence of unevenness on the molecular adhesive surface and dramatically improve the smoothness of the laminate of the laminated optical film.

[0023] In the laminated optical film according to the present invention, at least the retardation film and an optical film other than the polyvinyl alcohol film are laminated by a specific molecular adhesive layer, so that the variation in smoothness between the films constituting the laminated optical film is small. Specifically, when the laminate smoothness of the film having a large laminate smoothness arcmin value among the retardation film and the optical film according to the present invention is α, and the laminate smoothness of the entire laminated optical film is β, 0.93≦α / β≦1.05 When the above requirement is satisfied, the display unevenness caused by the adhesive layer can be further reduced, which is preferable. The laminated optical film according to the present invention is a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, and a polarizing film is further laminated on at least one of the laminated optical films, and the smoothness of the retardation film, the optical film, and the polarizing film can be maintained, which is preferable because the display unevenness caused by the adhesive layer can be further reduced. [Brief description of the drawings]

[0024] [Figure 1] 2 is an example of a schematic cross-sectional view of the laminated optical film C and the laminated optical film A according to Examples 1 to 3. [Diagram 2] 1 is an example of a schematic cross-sectional view of a laminated optical film C according to Comparative Examples 1-2. [Diagram 3] 1 is an example of a schematic cross-sectional view of a laminated optical film A' according to Examples 4 to 9. [Figure 4] 1 is an example of a schematic cross-sectional view of a laminated optical film A′ according to Comparative Examples 3 to 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The laminated optical film of the present invention is formed by laminating at least a retardation film and an optical film other than a polyvinyl alcohol film via a molecular adhesive layer, and is characterized in that, when the laminate smoothness of the entire laminated optical film is β, β<0.45 arcmin.

[0026] In the present invention, the "laminate smoothness" can be measured by the method described later. Not only the laminate smoothness of the entire laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, but also the laminate smoothness of the retardation film, the optical film other than the polyvinyl alcohol film, and the polarizing film can be measured by the same method.

[0027] The laminated optical film according to the present invention has excellent smoothness. Specifically, the smaller the value of the laminate smoothness arcmin, which is expressed in units of arcmin, the more preferable it is because it reduces display unevenness. In the present invention, the laminate smoothness of the entire laminated optical film is 0.45 arcmin or less, and more preferably 0.4 arcmin or less.

[0028] The laminated optical film according to the present invention is a film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer. When the laminate smoothness of a film having a larger laminate smoothness arcmin value among the retardation film and optical films constituting the laminated optical film is α, and the laminate smoothness of the entire laminated optical film is β, 0.93≦α / β≦1.05 When the condition above is satisfied, the variation in the laminate smoothness of each film constituting the laminated optical film is small, and the adverse effect on the smoothness caused by the molecular adhesive layer that laminates them is small, so that display unevenness can be reduced, which is preferable.

[0029] <Molecular adhesive layer> The laminated optical film according to the present invention includes a molecular adhesive layer. The molecular adhesive layer is formed of a cured layer of a molecular adhesive having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group. The molecular adhesive layer may be formed of a cured layer of only the molecular adhesive, or may be formed of a cured layer of a molecular adhesive-containing composition in which the molecular adhesive is diluted with a diluent such as water or an organic solvent and additives are added as necessary.

[0030] <Molecular adhesive> The molecular adhesive for forming the molecular adhesive layer included in the laminated optical film according to the present invention has at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group.

[0031] In the present invention, when a compound having a first reactive group RG1 and a second reactive group RG2 is used as the molecular adhesive, the first reactive group RG1 is at least one reactive group selected from the group consisting of an azide group, an amino group, an epoxy group, and an acryloyl group, and the second reactive group RG2 is at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group, the display unevenness caused by the adhesive layer can be reduced, which is preferable. More specifically, the molecular adhesive is represented by the following general formula (1): GE (1) (In the general formula (1), E is Si(R') n (OA) 3-n When a plurality of R's are present, each independently represents a chain hydrocarbon group having 1 to 4 carbon atoms. When a plurality of A's are present, each independently represents a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms. n represents an integer of 0 to 2. G represents a triazine ring C or an alkyl group D. Triazine ring C is Q 1 Q 2 in the side chain, and Q 1 and Q 2 are each independently N3 or -NR 1 (R 2 ) stands for R 1 and R 2each independently represents a hydrogen atom, a hydrocarbon group having 1 to 24 carbon atoms, an aminoalkyl group, or -R-Si(R') n (OA) 3-n The alkyl group D is a hydrocarbon group having 1 to 24 carbon atoms. 3 and Q 3 represents an azide group, an amino group, an epoxy group, or an acryloyl group. When a compound represented by the formula (I) is used, it is more preferable since unevenness in display caused by the adhesive layer can be reduced.

[0032] More specifically, in the present invention, it is particularly preferable to use, as the molecular adhesive, a triazine ring-containing compound having at least reactive group A and reactive group B, or an amino-based silane coupling agent, an epoxy-based silane coupling agent, or a mixture thereof.

[0033] <Triazine ring-containing compounds> In the present invention, the triazine ring-containing compound usable as a molecular adhesive has at least reactive group A and reactive group B. The reactive group A is at least one functional group selected from the group consisting of amino group, azide group, diazomethyl group, diazirine group, mercapto group, isocyanate group, ureido group, and epoxy group. The amino group may be an unsubstituted or substituted amino group, a primary ammonium group, a secondary ammonium group, a tertiary ammonium group, or a quaternary ammonium group, and preferably, for example, an aminoethyl group or an aminoethylamino group.

[0034] The reactive group B is at least one functional group selected from the group consisting of a silanol group and a group capable of generating a silanol group by hydrolysis. The group capable of generating a silanol group by hydrolysis is a group represented by "Si-Z", where Z is an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group, an n- or isopropoxy group, or a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0035] In the present invention, the triazine ring-containing compound is represented by the following general formula (1); [ka] (However, R 1 and R 2 is at least one functional group selected from the group consisting of an amino group, an azide group, a diazomethyl group, a diazirine group, a mercapto group, an isocyanate group, a ureido group, and an epoxy group; R 1 and R 2 and may be the same or different functional groups. Y is a divalent organic group. X is at least one functional group selected from the group consisting of a silanol group and a group capable of generating a silanol group by hydrolysis. A triazine ring-containing compound represented by the formula (I) is preferred. Y is an alkylene group having 1 to 10 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and the amino group and the group capable of generating a silanol group by hydrolysis are the same as those described above.

[0036] From the viewpoint of maintaining the smoothness of the retardation film, the triazine ring-containing compound represented by the general formula (1) is R 1 and R 2 or a triazine ring-containing compound in which either or both of R 1 and R 2 A triazine ring-containing compound in which either or both of the above are azide groups is preferred.

[0037] <Silane coupling agent> In the present invention, examples of silane coupling agents that can be used as molecular adhesives include amino-based silane coupling agents, epoxy-based silane coupling agents, and mixtures thereof.

[0038] The amino-based silane coupling agent is an organosilicon compound containing an amino group, and examples thereof include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and hydrochlorides thereof. Commercially available amino silane coupling agents include KBM-602, KBM-603, KBM-903, KBE-603, KBE-903, X-12-972F (all manufactured by Shin-Etsu Chemical Co., Ltd.), Z-6011, Z-6020, Z-6026, Z-6032, Z-6094, Z-6610 (all manufactured by Dow Corning Toray Co., Ltd.), A-1100, A-1110, A-1120, A-2120, Y-9669 (all manufactured by Momentive Performance Materials, Inc.), and the like.

[0039] The epoxy-based silane coupling agent is an organosilicon compound containing an epoxy group, and examples thereof include 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. Commercially available epoxy silane coupling agents include KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KR-516, X-12-981S (all manufactured by Shin-Etsu Chemical Co., Ltd.), SH6040, Z-6040, Z-6042, Z-6043, Z-6044 (all manufactured by Dow Corning Toray Co., Ltd.), A-186, A-187, A-1871 (all manufactured by Momentive Performance Materials, Inc.), and the like.

[0040] The molecular adhesive used in the present invention can form a strong covalent bond with a retardation film, an optical film other than a polyvinyl alcohol film, and even a polarizing film. Therefore, even if the molecular adhesive layer according to the present invention is thin, it can ensure sufficient adhesion to the adherend. Therefore, from the viewpoint of thinning the laminated optical film, the thickness of the molecular adhesive layer is preferably 1 nm or more and 100 nm or less, more preferably 2 nm or more and 80 nm or less, and even more preferably 3 nm or more and 60 nm or less.

[0041] <Retardation film> The laminated optical film according to the present invention may have at least one retardation film and may be laminated with an optical film other than a polyvinyl alcohol film via a molecular adhesive layer. In the present invention, however, it is preferable that the laminated optical film is a laminated optical film in which two retardation films are laminated via a molecular adhesive layer, which is particularly required to have excellent laminate smoothness from the viewpoint of suppressing display unevenness. The retardation film may be a retardation film having a front retardation of 40 nm or more and / or a thickness direction retardation of 80 nm or more. The front retardation is usually controlled to be in the range of 40 to 200 nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm. The retardation film may be a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, or a film in which an oriented layer of a liquid crystal polymer is supported by a film. The thickness of the retardation film may be about 1 to 150 μm, but from the viewpoint of thinning, it is preferable to use a retardation film having a thickness of 5 μm or less.

[0042] The retardation film may be one represented by 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) (wherein Re

[0450] and Re

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

[0043] When the retardation film is a film in which an orientation layer of a liquid crystal polymer is supported by a base film, the orientation layer of the liquid crystal polymer alone has poor shape retention, and therefore, the laminate smoothness of the retardation film in this case is measured in a state in which the orientation layer of the liquid crystal polymer is laminated on the base film.

[0044] In the laminated optical film according to the present invention, optical films that can be used other than the retardation film include optical films other than polyvinyl alcohol films, such as resin protective films and polarizing films having at least a polarizer and a resin protective film.

[0045] <Polarizer> In the present invention, from the viewpoint of thinning, the thickness of the polarizer is preferably 10 μm or less, more preferably 5 μm or less. Examples of such polarizers include those obtained by adsorbing iodine to a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, and then uniaxially stretching the film.

[0046] A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and stretching it uniaxially can be produced, for example, by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, the polyvinyl alcohol-based film may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution of potassium iodide or the like. 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 can wash off dirt and blocking inhibitors on the surface of the polyvinyl alcohol-based film, and also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, or may be stretched while dyeing, or may be dyed with iodine after stretching. Stretching can be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

[0047] Representative 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, International Publication No. 2014 / 077636, or thin polarizers obtained by the manufacturing methods described therein.

[0048] Among the thin polarizers including the steps of stretching and dyeing the laminate, those obtained by the steps including the steps of stretching in an aqueous boric acid solution as described in Japanese Patent Nos. 4751486, 4751481, and 4815544 are preferred because they can be stretched at a high ratio and have improved polarization performance, and those obtained by the steps including the steps of supplementary air stretching before stretching in an aqueous boric acid solution as described in Japanese Patent Nos. 4751481 and 4815544 are particularly preferred. These thin polarizers can be obtained by the steps including the steps of stretching a polyvinyl alcohol resin (hereinafter also referred to as PVA resin) layer and a resin substrate for stretching in a laminate and the steps of dyeing. With this method, even if the PVA resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the resin substrate for stretching.

[0049] <Resin protective film> As a material for constituting the resin protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose-based 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 resin protective film may contain one or more types of any appropriate additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the thermoplastic resin in the resin protective film is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, even more preferably 60 to 98% by mass, and particularly preferably 70 to 97% by mass. If the content of the thermoplastic resin in the resin protective film is 50% by mass or less, the inherent properties of the thermoplastic resin, such as high transparency, may not be fully exhibited.

[0050] The material for forming the resin protective film is preferably one having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc., and in particular, a moisture permeability of 150 g / m 2 / 24h or less is more preferable, and 140g / m 2 / 24h or less is particularly preferred, and 120g / m 2 / 24h or less is even more preferable.

[0051] A functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, etc. may be provided on the surface of the resin protective film to which the polarizer is not adhered. The functional layer such as the hard coat layer, the anti-reflection layer, the anti-sticking layer, the diffusion layer, the anti-glare layer, etc. may be provided on the resin protective film itself, or may be provided separately from the resin protective film.

[0052] The thickness of the resin protective film can be appropriately determined, but is generally about 1 to 500 μm, preferably 1 to 200 μm, and more preferably 1 to 80 μm, from the standpoints of strength, workability such as handleability, and thinness.

[0053] <Polarizing film> Examples of the polarizing film include a polarizing film in which a resin protective film is laminated on at least one surface of a polarizer through a pressure-sensitive adhesive layer, a normal adhesive layer which is a cured layer of an active energy ray curable adhesive, or the above-mentioned molecular adhesive layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a pressure-sensitive adhesive having a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, or a rubber-based polymer can be appropriately selected and used. In particular, a pressure-sensitive adhesive having excellent optical transparency, moderate wettability, cohesiveness, and adhesive properties, and excellent weather resistance and heat resistance, such as an acrylic pressure-sensitive adhesive, can be preferably used. The adhesive layer is formed by a cured layer of an adhesive composition containing at least a polymerizable compound, and is preferably formed by a cured layer of an active energy ray curable adhesive composition such as an electron beam curable adhesive, an ultraviolet ray curable adhesive, or a visible light curable adhesive. The active energy ray curable adhesive composition can be divided into a radical polymerization curable adhesive composition and a cationic polymerization adhesive composition. The thickness of the polarizing film can be appropriately determined, but from the viewpoint of making the laminated optical film thinner, it is preferably from 10 to 500 μm, and more preferably from 20 to 150 μm.

[0054] The laminated optical film according to the present invention may be a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, and a polarizing film is further laminated on at least one of the laminated optical films. Even in such a laminated optical film, when the laminate smoothness of the entire laminated optical film is β', it is preferable that β'<0.45 arcmin. Here, when the laminate smoothness of the film having the larger laminate smoothness arcmin value among the retardation film, the optical film, and the polarizing film is α', and the laminate smoothness of the entire laminated optical film is β', 0.93≦α' / β'≦1.05 When the condition above is satisfied, the variation in the laminate smoothness of each film constituting the laminated optical film is small, and the adverse effect on the smoothness caused by the molecular adhesive layer that laminates them is small, so that display unevenness can be reduced, which is preferable.

[0055] The laminated optical film according to the present invention can be produced, for example, by the following production method. A laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, the laminated optical film comprising: a coating step of coating a molecular adhesive on one or both of a bonding surface of the retardation film and a bonding surface of the optical film other than the polyvinyl alcohol film; a bonding step of bonding the retardation film and the optical film other than the polyvinyl alcohol film together; and a bonding step of bonding the retardation film and the optical film other than the polyvinyl alcohol film together via the molecular adhesive layer obtained by curing the molecular adhesive by irradiating active energy rays from the retardation film surface side or the optical film surface side other than the polyvinyl alcohol film, or by heating the laminated retardation film and the optical film other than the polyvinyl alcohol film, the molecular adhesive layer is a cured layer of a molecular adhesive having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group; A method for producing a laminated optical film, in which β is a laminate smoothness of the entire laminated optical film, and β is less than 0.45 arcmin. Each step will be described below.

[0056] <Coating process> In the coating step, the molecular adhesive is applied to either or both of the lamination surface of the retardation film and the lamination surface of the optical film other than the polyvinyl alcohol film. In coating, the molecular adhesive may be directly applied, or may be applied as a molecular adhesive-containing composition in which a solvent and / or additives are added to the molecular adhesive. The solvent is preferably one that can stabilize the molecular adhesive and dissolve or disperse it. The solvent may be an organic solvent, water, or a mixture thereof. The solvent may be selected from, for example, esters such as ethyl acetate, butyl acetate, and 2-hydroxyethyl acetate; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl-n-propyl ketone, and acetylacetone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, and cyclohexanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether; and glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate. Examples of additives include binder resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, titanium coupling agents, inorganic or organic fillers, metal powders, particles, foils, etc. The binder resins may be transparent, and examples thereof include polymers such as acrylic resins, styrene resins, polyvinyl alcohol resins, urethane resins, polyester resins, polypropylene resins, polyethylene resins, epoxy resins, and polycarbonate resins.

[0057] When a molecular adhesive-containing composition is prepared by adding a solvent and / or additives to the molecular adhesive, the concentration of the molecular adhesive in the molecular adhesive-containing composition is not particularly limited. The concentration is preferably 0.05 to 10.00 mass%, more preferably 0.10 to 1.00 mass. By making the concentration of the molecular adhesive 0.05 mass% or more, the molecular adhesive can be efficiently applied onto an optical film other than a retardation film and / or a polyvinyl alcohol film. In addition, by making the concentration 10.00 mass% or less, unintended reactions in the molecular adhesive-containing composition can be suppressed, and the stability of the solution is excellent.

[0058] The method of directly applying the molecular adhesive or applying a molecular adhesive-containing composition by adding a solvent and / or additives to the molecular adhesive is appropriately selected depending on the viscosity of the molecular adhesive or composition and the desired thickness, and examples thereof include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, and a rod coater. The viscosity of the molecular adhesive-containing composition is preferably 1 to 100 mPa·s, more preferably 1 to 50 mPa·s, and most preferably 1 to 30 mPa·s. If the viscosity of the composition is high, the surface smoothness after application is poor, which is undesirable since it causes poor appearance.

[0059] When a molecular adhesive-containing composition in which a solvent and / or additives are added to the molecular adhesive is used, a drying step may be provided after the coating step to remove the solvent, if necessary. The drying step may be air drying or heating to a degree that does not cause the molecular adhesive to react or denature.

[0060] For optical films other than the retardation film and the polyvinyl alcohol film, and for polarizing films when a polarizing film is laminated, it is preferable to perform a surface modification treatment before the coating process. Examples of the surface modification treatment include corona treatment, plasma treatment, and itro treatment, and corona treatment is particularly preferable. By performing corona treatment, reactive functional groups such as carbonyl groups and amino groups are generated on the surface of the adherend, improving the adhesion with the molecular adhesive layer. In addition, the ashing effect removes foreign matter on the surface of the adherend and reduces surface unevenness, making it possible to create a laminated optical film with excellent appearance characteristics.

[0061] <Lamination process> An optical film other than the retardation film and the polyvinyl alcohol film is laminated via the molecular adhesive applied as described above using a roll laminator or the like.

[0062] <Adhesion process> After laminating the retardation film and the optical film other than the polyvinyl alcohol film, the molecular adhesive is cured by irradiating with active energy rays (electron beams, ultraviolet rays, visible rays, etc.) or by heating the laminated retardation film and the optical film other than the polyvinyl alcohol film to form a molecular adhesive layer. When heating, the heating conditions are preferably, for example, heating at 40°C for 24 hours. When irradiating with active energy rays (electron beams, ultraviolet rays, visible rays, etc.), the irradiation direction can be any appropriate direction.

[0063] The irradiation conditions for irradiating the electron beam can be any suitable condition as long as the molecular adhesive can be cured. For example, the acceleration voltage of the electron beam irradiation is preferably 5 kV to 300 kV, more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the molecular adhesive, resulting in insufficient curing, and if the acceleration voltage is more than 300 kV, the penetration force through the sample is too strong, resulting in damage to optical films other than the retardation film and the polyvinyl alcohol 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 molecular adhesive may be insufficiently cured, and if it exceeds 100 kGy, the optical films other than the retardation film and the polyvinyl alcohol film may be damaged, resulting in a decrease in mechanical strength and yellowing, and the desired optical characteristics cannot be obtained.

[0064] Electron beam irradiation is usually performed in an inert gas, but may be performed in the air or with a small amount of oxygen introduced if necessary. Depending on the material of the optical film other than the retardation film and the polyvinyl alcohol film, oxygen inhibition can be intentionally caused in the optical film other than the retardation film and the polyvinyl alcohol film that is first hit by the electron beam by appropriately introducing oxygen, and damage to the optical film other than the retardation film and the polyvinyl alcohol film can be prevented, and the molecular adhesive can be efficiently irradiated with the electron beam only.

[0065] When the laminated optical film according to the present invention is produced in a continuous line, the line speed depends on the curing time of the molecular adhesive, 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 slow, the productivity is poor, or the damage to the optical films other than the retardation film and the polyvinyl alcohol film is too great, and a laminated optical film that can withstand a durability test or the like cannot be produced. If the line speed is too high, the molecular adhesive may not be cured sufficiently, and the desired adhesiveness may not be obtained.

[0066] The obtained laminated optical film may be provided with an adhesive layer for adhering to other members such as a liquid crystal cell, etc. The adhesive for forming the adhesive layer may be the same as that described above.

[0067] The exposed surface of the adhesive layer is covered with a separator temporarily attached to prevent contamination until it is put into practical use. This prevents contact with the adhesive layer during normal handling. As the separator, apart from the above thickness conditions, any suitable thin material such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, or a laminate thereof, which is coated with a suitable release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based material as necessary, may be used in accordance with conventional methods.

[0068] The laminated optical film of the present invention can be preferably used for forming various devices such as liquid crystal display devices and organic EL display devices. Various image display devices can be formed in a conventional manner. In other words, various image display devices are generally formed by appropriately assembling components such as an image display cell, a polarizing film or an optical film, and an illumination system as necessary, and incorporating a driving circuit, but in the present invention, there is no particular limitation except that the polarizing film or optical film according to the present invention is used, and the conventional manner can be followed. As for the image display cell, any type such as a TN type, STN type, or π type can be used.

[0069] It is possible to form an appropriate image display device, such as an image display device in which an optical laminate is arranged on one or both sides of an image display cell, or an image display device using a backlight or a reflector 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 image display cell. When optical laminates are provided on both sides, they may be the same or different. Furthermore, when forming an image display device, appropriate parts such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc. can be arranged in one or more layers at appropriate positions. EXAMPLES

[0070] Examples of the present invention are described below, but the embodiments of the present invention are not limited thereto.

[0071] The smoothness of the laminate of the laminated optical film, and the retardation film 1 (λ / 2 retardation film), the retardation film 2 (λ / 4 retardation film), and the polarizing film was measured by the following method.

[0072] [Laminate smoothness] The smoothness of the laminate was measured using a phase-shifting laser interferometer (Zygo, product name "DynaFiz"). Specifically, a sample was attached to a microslide glass (Matsunami Glass Industry, product name "S200200") with a 5 μm thick acrylic adhesive layer with little unevenness to obtain a measurement sample. The measurement sample was placed on a measurement table with a vibration-proof table, and a single-wavelength (633 nm) laser was used to interfere with a standard with guaranteed flatness, and the relative displacement within a specified area (a circle with a diameter of 30 mm) was measured. For the analysis, the value obtained by doubling the "Slope maginitude RMS", an index of the angle obtained by extracting the frequency values ​​of 0.1 / mm to 1 / mm (corresponding to 2σ), was defined as the smoothness of the laminate (unit: arcmin). At this time, the adhesive used was 0.25 arcmin or less.

[0073] <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 concentration of 30% by weight. A surfactant (BYK-360, BYK-Chemie) and a photopolymerization initiator (IGM Resins' "Omnirad907") were added to this solution to prepare a photopolymerizable liquid crystal composition that serves as a raw material for manufacturing a retardation film. The amounts of the leveling agent and the polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, relative to 100 parts by weight of the photopolymerizable liquid crystal compound.

[0074] <Retardation film> Retardation film 1 and retardation film 2 were produced by the following method using the photopolymerizable liquid crystal composition prepared above as a raw material.

[0075] <Retardation film 1 (λ / 2 retardation film)> A biaxially stretched norbornene film (ZEONORFILM manufactured by ZEON Corporation, thickness: 33 μm, front retardation: 135 nm) was used as a substrate, and the above liquid crystal composition was applied to the substrate with a bar coater so that the phase difference was λ / 2, and the liquid crystal was aligned by heating at 100° C. for 3 minutes. After cooling to room temperature, the liquid crystal was aligned in a nitrogen atmosphere with an accumulated light amount of 400 mJ / cm 2 . 2 The laminate was then photocured by irradiating it with ultraviolet light of 1000 nm to obtain a laminate having a structure of a substrate / first liquid crystal alignment solidified layer. The first liquid crystal alignment solidified layer had a homogeneous alignment, a thickness of 2 μm, and a laminate smoothness of the first liquid crystal alignment solidified layer (λ / 2 retardation film) was 0.3 arcmin.

[0076] <Retardation film 2 (λ / 4 retardation film)> A biaxially stretched norbornene film (ZEON Corporation's "ZEONORFILM", thickness: 33 μm, front retardation: 135 nm) was used as a substrate, and the above liquid crystal composition was applied to the substrate with a bar coater so that the phase difference was λ / 4, and the substrate was heated at 100°C for 3 minutes to align the liquid crystal. After cooling to room temperature, the substrate was irradiated with ultraviolet light with an integrated light quantity of 400 mJ / cm2 in a nitrogen atmosphere to perform photocuring, thereby obtaining a laminate having a substrate / second liquid crystal alignment solidified layer configuration. The second liquid crystal alignment solidified layer was homogeneously oriented, had a thickness of 2 μm, and the laminate smoothness of the second liquid crystal alignment solidified layer (λ / 4 phase difference film) was 0.3 arcmin.

[0077] <Laminated Optical Film A> Examples 1 to 3 and Comparative Examples 1 to 2 The first liquid crystal alignment solidified layer (λ / 2 retardation film) surface of the laminate having the structure of substrate / first liquid crystal alignment solidified layer (λ / 2 retardation film) and the second liquid crystal alignment solidified layer (λ / 4 retardation film) surface of the laminate having the structure of substrate / second liquid crystal alignment solidified layer (λ / 4 retardation film) were treated with a corona treatment machine at a treatment density of 50 W·min / m2 Using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 1000 / inch, rotation speed 130% / to line speed), the molecular adhesive or adhesive composition shown below was applied to the corona-treated first liquid crystal alignment solidified layer (λ / 2 retardation film) surface and the second liquid crystal alignment solidified layer (λ / 4 retardation film) surface, respectively, to a coating thickness of 1 μm. Examples 1 and 2: 1% by mass aqueous solution or 5% by mass aqueous solution of molecular adhesive A (N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (manufactured by Io Chemical Research Institute)) Example 3: 10% by weight aqueous solution of molecular adhesive A Comparative Example 1: Active energy ray-curable adhesive composition A obtained by mixing 20 parts by mass of N-acryloylmorpholine (manufactured by KJ Chemicals), 10 parts by mass of Plaxel FA1DDM (manufactured by Daicel), 60 parts by mass of Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical), 5 parts by mass of ARUFON UP-1190 (manufactured by Toagosei), 3 parts by mass of Omnirad907 (manufactured by IGM Resins BV), and 3 parts by mass of KAYACURE DETX-S (manufactured by Nippon Kayaku). Comparative Example 2: Water-based adhesive composition A, which is a 3% by mass aqueous solution containing an acetoacetyl group-containing polyvinyl alcohol resin (average polymerization degree 1,200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1

[0078] After coating the molecular adhesive or adhesive composition shown above, the surface of the λ / 4 retardation film coated with the molecular adhesive or adhesive composition and the surface of the λ / 2 retardation film coated with the molecular adhesive or adhesive composition were laminated together using a roll machine so that the slow axis of the λ / 4 retardation film was in a 60° relationship with the slow axis of the λ / 2 retardation film (the line speed for lamination was 15 m / min). Then, in Examples 1 to 3, the laminated optical film (referred to as "laminated optical film C") in which the λ / 4 retardation film and the λ / 2 retardation film with the biaxially stretched norbornene-based film were laminated was obtained by leaving the film at 40° C. for 24 hours, and then the biaxially stretched norbornene film was peeled off from both sides of the obtained laminated optical film C to obtain a laminated optical film (referred to as "laminated optical film A"). FIG. 1 shows the configurations of the laminated optical film C and the laminated optical film A according to Examples 1 to 3. In FIG. 1, C indicates the laminated optical film C, 1 indicates the retardation film 1 (λ / 2 retardation film), 2 indicates the retardation film 2 (λ / 4 retardation film), 3 indicates the molecular adhesive layer, and N indicates the biaxially stretched norbornene-based film. The laminate smoothness of the entire laminated optical film A (a laminated optical film in which retardation films are laminated via a molecular adhesive layer) obtained by peeling off the biaxially stretched norbornene film N from both sides of the laminated optical film C is defined as β. In addition, the laminate smoothness of the film having a larger laminate smoothness arcmin value among the laminate smoothness of the retardation film 1 and the laminate smoothness of the retardation film 2 is defined as α.

[0079] In Comparative Example 1, a visible light irradiation device (Heraeus Light HAMMER10 Mark III, bulb: V bulb, peak illuminance: 1600 mW / cm ) was used from the λ / 4 phase difference film side. 2 , cumulative dose 1000 / mJ / cm 2The illuminance and cumulative dose of the active energy rays were measured using Power Puck 2 (manufactured by EIT, UVV measurement value) to irradiate the active energy rays to cure the adhesive composition, thereby obtaining a laminated optical film (hereinafter referred to as "Laminated Optical Film C") in which a λ / 4 retardation film and a λ / 2 retardation film with a biaxially stretched norbornene-based film were laminated through a cured layer of the adhesive composition. In Comparative Example 2, a laminated optical film (hereinafter referred to as "Laminated Optical Film C") in which a λ / 2 retardation film and a λ / 4 retardation film with a biaxially stretched norbornene-based film were laminated was obtained by heating and drying for 4 minutes at 60°C. FIG. 2 shows the configuration of the laminated optical film C according to Comparative Examples 1 and 2. 2, C indicates laminated optical film C, 1 indicates retardation film 1 (λ / 2 retardation film), 2 indicates retardation film 2 (λ / 4 retardation film), 4 indicates an adhesive layer which is a cured layer of an active energy ray-curable adhesive composition or an aqueous adhesive composition, and N indicates a biaxially stretched norbornene-based film. As described later, laminated optical film A could not be produced from laminated optical film C according to Comparative Examples 1 and 2, and therefore, when the laminate smoothness of the entire laminated optical film A was defined as β, it was impossible to measure β.

[0080] Table 1 shows the laminate smoothness β (arcmin) for the laminated optical films A of Examples 1 to 3. Since the laminate smoothness of the λ / 4 retardation film and the λ / 2 retardation film constituting the laminated optical film A was both 0.3 arcmin, the laminate smoothness α of the film having the larger laminate smoothness arcmin value among the λ / 4 retardation film and the λ / 2 retardation film constituting the laminated optical film A was set to 0.3 arcmin. In Table 1, the adhesion and (molecular) adhesive layer thickness of the laminated optical film A were evaluated by the following methods.

[0081] [(Molecular) adhesive layer thickness (nm) (TEM measurement)] Cross-sectional TEM observation was performed using a Hitachi HT7820 with a frozen ultrathin section method including heavy metal staining. The accelerating voltage during the measurement was set to 100 kV.

[0082] [Adhesion] Regarding laminated optical film C, which is a stage prior to peeling off the biaxially stretched norbornene films from both sides of laminated optical film A, when the biaxially stretched norbornene-based film was peeled off, the adhesion was judged to be "x" when peeling occurred between the λ / 4 retardation film and the λ / 2 retardation film, and the adhesion was judged to be "good" when peeling occurred between the biaxially stretched norbornene-based film and the retardation film.

[0083] [Table 1]

[0084] From the results in Table 1, it can be seen that the laminated optical films A of Examples 1 to 3 have excellent adhesion between the retardation film 1 and the retardation film 2, and further have excellent smoothness of the molecular adhesive layer, which results in excellent smoothness of the entire laminated optical film A. On the other hand, in Comparative Examples 1 and 2, for the laminated optical film C, which is a precursor to the laminated optical film A, when the biaxially stretched norbornene-based film was peeled off, peeling occurred between the λ / 4 retardation film and the λ / 2 retardation film, so that the laminated optical film A could not be manufactured, and when the laminate smoothness of the entire laminated optical film A was taken as β, β could not be measured.

[0085] Hereinafter, a production example of a laminated optical film will be described in which a polarizing film is further laminated on at least one of the laminated optical films in which two retardation films are laminated via a molecular adhesive layer.

[0086] <Polarizer> A polyvinyl alcohol film with an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 45 μm was prepared. The polyvinyl alcohol film was stretched 2.2 times in the conveying direction while swelling by immersing in a swelling bath (water bath) at 30° C. between rolls with different peripheral speed ratios (swelling step), and then stretched 3.3 times in the conveying direction based on the original polyvinyl alcohol film (polyvinyl alcohol film not stretched at all in the conveying direction) while dyeing by immersing in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at 30° C. for 30 seconds while adjusting the iodine concentration so that the polarizer has a predetermined transmittance (dyeing step). Next, the dyed polyvinyl alcohol film was immersed in a 40°C crosslinking bath (aqueous solution with a boric acid concentration of 3.5% by weight, a potassium iodide concentration of 3.0% by weight, and a zinc sulfate concentration of 3.6% by weight) for 28 seconds, and stretched to 3.6 times in the conveying direction based on the original polyvinyl alcohol film (crosslinking step). Furthermore, the obtained polyvinyl alcohol film was immersed in a 64°C stretching bath (aqueous solution with a boric acid concentration of 4.8% by weight, a potassium iodide concentration of 5.0% by weight, and a zinc sulfate concentration of 5.0% by weight) for 60 seconds, and stretched to 6.0 times in the conveying direction based on the original polyvinyl alcohol film (stretching step), and then immersed in a 29°C cleaning bath (potassium iodide concentration of 2.3% by weight) for 10 seconds (cleaning step). The washed polyvinyl alcohol film was dried at 40°C for 30 seconds to prepare a polarizer. The polarizer had a thickness of 18 μm.

[0087] <Polarizing film> As the adhesive, an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group (average polymerization degree 1,200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylol melamine in a weight ratio of 3:1 was used. Using this adhesive, a 39 μm-thick triacetyl cellulose film (manufactured by Konica Minolta, product name "KC4UY") having a hard coat layer as a transparent protective film was laminated on one side of the polarizer obtained above via a water-based adhesive layer, and a 30 μm-thick acrylic film (manufactured by Nippon Shokubai, RX420) was laminated on the other side via a water-based adhesive layer using a roll laminator, and then the film was heated and dried in an oven (temperature 60°C, time 4 minutes) to produce polarizing film 1. The laminate smoothness of polarizing film 1 was 0.42 arcmin.

[0088] <Acrylic polymer> In a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 92 parts by weight of butyl acrylate, 5 parts by weight of N-acryloylmorpholine (ACMO), 2.9 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 200 parts by weight of ethyl acetate were charged, and nitrogen gas was introduced while gently stirring to replace the atmosphere with nitrogen. The liquid temperature in the flask was kept at around 55°C, and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. The weight-average molecular weight of the above acrylic polymer was 1.78 million.

[0089] <Acrylic adhesive> The acrylic polymer solution was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical, thickness: 38 μm), and dried and crosslinked at 150° C. for 3 minutes to form a pressure-sensitive adhesive layer with a thickness of 5 μm after drying. The gel fraction of the pressure-sensitive adhesive layer at this time was 83% by weight, and the decomposition amount of peroxide after drying was 91% by weight.

[0090] <Laminated Optical Film A'> Examples 4 to 9 and Comparative Examples 3 to 4 The acrylic film surface of the polarizing film and the first liquid crystal alignment solidified layer surface of the λ / 2 retardation film were treated with a corona treatment machine at a treatment density of 50 W·min / m 2 Then, in Examples 4 to 8 and Comparative Examples 3 and 4, the acrylic pressure-sensitive adhesive was used to bond the acrylic film surface of the polarizing film and the first liquid crystal alignment solidified layer surface of the λ / 2 retardation film by a roller so that the slow axis of the λ / 2 retardation film was in a relationship of 15° with the transmission axis of the polarizer (the line speed for bonding was 15 m / min), thereby producing a polarizing film with a λ / 2 retardation film in which the polarizing film and the λ / 2 retardation film were laminated. In Example 9, a 1% by mass aqueous solution of molecular adhesive A (N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (Io Chemical Research Institute)) was applied to the acrylic film surface of the polarizing film and the first liquid crystal alignment solidified layer surface of the λ / 2 retardation film using an MCD coater (manufactured by Fuji Machine Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 1000 rolls / inch, rotation speed 130% / to line speed) so that the total coating thickness was 1 μm, and the λ / 2 retardation film was laminated with a roll machine so that the slow axis of the λ / 2 retardation film was in a 15° relationship with the transmission axis of the polarizer (the line speed for lamination was 15 m / min), and the film was left to stand at 40° C. for 24 hours to produce a polarizing film with a λ / 2 retardation film in which the polarizing film and the λ / 2 retardation film were laminated.

[0091] The biaxially stretched norbornene film of the polarizing film with the λ / 2 retardation film was peeled off, and the λ / 2 retardation film surface and the second liquid crystal alignment solidified layer surface of the λ / 4 retardation film were treated with a corona treatment machine at a density of 50 W min / m. 2 Using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 1000 rolls / inch, rotation speed 140% / to line speed), the molecular adhesive or adhesive composition shown below was applied to the λ / 2 retardation film surface of the polarizing film with the λ / 2 retardation film and the second liquid crystal alignment solidified layer surface of the λ / 4 retardation film, which had been subjected to the corona treatment. Example 4: 0.1% by mass aqueous solution of molecular adhesive A (N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (manufactured by Io Chemical Research Institute)) Example 5: 1% by weight aqueous solution of molecular adhesive A (using a gravure roll line count of 1500 lines / inch) Examples 6 and 9: 1% by weight aqueous solution of molecular adhesive A Example 7: 1% by mass aqueous solution of molecular adhesive B (3-aminopropyltrimethoxysilane (Tokyo Chemical Industry Co., Ltd.)) Example 8: 1% by mass aqueous solution of molecular adhesive C (a mixture of KBM-603 and KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) in a weight ratio of 30:70) Comparative Example 3: Active energy ray-curable adhesive composition A obtained by mixing 20 parts by mass of N-acryloylmorpholine (manufactured by KJ Chemicals), 10 parts by mass of Plaxel FA1DDM (manufactured by Daicel), 60 parts by mass of Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical), 5 parts by mass of ARUFON UP-1190 (manufactured by Toagosei), 3 parts by mass of Omnirad907 (manufactured by IGM Resins BV), and 3 parts by mass of KAYACURE DETX-S (manufactured by Nippon Kayaku). Comparative Example 4: Cationic polymerizable composition A obtained by mixing 65 parts of Celloxide 2021P (manufactured by Daicel Corporation), 35 parts of neopentyl glycol diglycidyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2.25 parts of triarylsulfonium hexafluorophosphate (manufactured by Sanyo Chemical Industry Co., Ltd.)

[0092] After coating with the molecular adhesive or adhesive composition described above, the film was laminated to the λ / 2 retardation film surface using a roller so that the slow axis of the λ / 4 retardation film was in a 75° relationship with the transmission axis of the polarizer (the lamination line speed was 15 m / min). Then, in Comparative Examples 3 and 4, an active energy ray irradiation device (Light HAMMER10 Mark III manufactured by Heraeus, bulb: V bulb, peak illuminance: 1600 mW / cm) was used from the λ / 4 retardation film side. 2 , cumulative irradiation dose 1000mJ / cm 2The illuminance and cumulative dose of the active energy rays were measured by irradiating the active energy rays using Power Puck 2 (manufactured by EIT, measured value of UVV) and peeling off the biaxially stretched norbornene film of the λ / 4 retardation film to produce a laminated optical film (hereinafter referred to as "laminated optical film A'") in which a polarizing film with a λ / 2 retardation film and a λ / 4 retardation film were laminated. In Examples 4 to 9, the film was left at 40°C for 24 hours, and the biaxially stretched norbornene film of the λ / 4 retardation film was peeled off to produce a laminated optical film (hereinafter referred to as "laminated optical film A'") in which a polarizing film with a λ / 2 retardation film and a λ / 4 retardation film were laminated. FIG. 3 shows the configuration of the laminated optical film A' according to Examples 4 to 9. In FIG. 3, A' indicates the laminated optical film A', 1 indicates the retardation film 1 (λ / 2 retardation film), 2 indicates the retardation film 2 (λ / 4 retardation film), 3 indicates the molecular adhesive layer, 5 indicates the pressure-sensitive adhesive layer or molecular adhesive layer, and 6 indicates the polarizing film. The laminate smoothness of the entire laminated optical film A' (a laminated optical film in which a polarizing film is further laminated on one side of a laminated optical film in which a retardation film and a retardation film are laminated via a molecular adhesive layer) is defined as β'. In addition, the laminate smoothness of the film with the larger laminate smoothness arcmin value among the laminate smoothness of the retardation film 1 (λ / 2 retardation film), the laminate smoothness of the retardation film 2 (λ / 4 retardation film), and the laminate smoothness of the polarizing film is defined as α'.

[0093] FIG. 4 shows the structure of the laminated optical film A' according to Comparative Examples 3 to 4. In FIG. 4, A' indicates the laminated optical film A', 1 indicates the retardation film 1 (λ / 2 retardation film), 2 indicates the retardation film 2 (λ / 4 retardation film), 4 indicates the adhesive layer which is the cured layer of the active energy ray curable adhesive composition, 5 indicates the pressure sensitive adhesive layer or the molecular adhesive layer, and 6 indicates the polarizing film. The laminate smoothness of the entire laminated optical film A' (a laminated optical film in which a polarizing film is further laminated on one side of a laminated optical film in which a retardation film and a retardation film are laminated via a molecular adhesive layer) is defined as β'. In addition, the laminate smoothness of the film having a larger numerical value of the laminate smoothness arcmin among the laminate smoothness of the retardation film 1 (λ / 2 retardation film), the laminate smoothness of the retardation film 2 (λ / 4 retardation film), and the laminate smoothness of the polarizing film is defined as α'.

[0094] For the laminated optical films A' of Examples 4 to 9 and Comparative Examples 3 and 4, the laminate smoothness β' (arcmin) and the presence or absence of display unevenness caused by the adhesive layer are shown in Table 2. The laminate smoothness of the λ / 4 retardation film and the λ / 2 retardation film constituting the laminated optical film A' was both 0.3 arcmin, but the laminate smoothness of the polarizing film 1 was 0.42 arcmin, so the laminate smoothness α' of the polarizing film 1, which has the largest laminate smoothness arcmin value among the λ / 4 retardation film, the λ / 2 retardation film and the polarizing film 1 constituting the laminated optical film A', was determined to be 0.42 arcmin.

[0095] [Whether or not display unevenness occurs due to the adhesive layer] When the laminated optical film A' was attached to a blackboard, it was evaluated based on whether color unevenness due to the (molecular) adhesive layer could be visually recognized. If it was not visible, it was judged as "◯" that no display unevenness occurred, and if it was visible, it was judged as "×" that display unevenness occurred.

[0096] [Table 2]

[0097] From the results in Table 2, it can be seen that the laminated optical films A' of Examples 4 to 9 have excellent adhesion between the retardation film 1 and the retardation film 2, and furthermore, due to the excellent smoothness of the molecular adhesive layer, the laminated optical film A' as a whole has excellent smoothness. It can also be seen that no display unevenness occurs due to the excellent surface smoothness of the laminate. On the other hand, in the laminated optical films A' of Comparative Examples 3 and 4, it is necessary to make the adhesive layer considerably thick in order to ensure adhesion, so that the numerical value of the laminate smoothness arcmin becomes large, and it can be seen that display unevenness occurs.

Claims

1. A laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, The molecular adhesive layer is a cured layer of a molecular adhesive having at least one reactive group selected from the group consisting of a silanol group and an alkoxysilyl group, When the laminate smoothness of the entire laminated optical film is β, β<0.45 arcmin A laminated optical film comprising:

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

3. The laminated optical film according to claim 1 , wherein the molecular adhesive layer has a thickness of 1 nm or more and 100 nm or less.

4. 2. The laminated optical film according to claim 1, wherein the retardation film has a thickness of 5 μm or less.

5. The molecular adhesive is a compound having a first reactive group RG1 and a second reactive group RG2, the first reactive group RG1 is at least one reactive group selected from the group consisting of an azide group, an amino group, an epoxy group, and an acryloyl group; The laminated optical film according to claim 1 , wherein the second reactive group RG2 is at least one type of reactive group selected from the group consisting of a silanol group and an alkoxysilyl group.

6. The molecular adhesive has the following general formula (1): G-E (1) (In the general formula (1), E is Si(R') ｎ (OA) ３－ｎ When a plurality of R's are present, each independently represents a chain hydrocarbon group having 1 to 4 carbon atoms. When a plurality of A's are present, each independently represents a hydrogen atom or a chain hydrocarbon group having 1 to 4 carbon atoms. n represents an integer of 0 to 2. G represents a triazine ring C or an alkyl group D. Triazine ring C is Q １ Q ２ in the side chain, and Q １ and Q. ２ are each independently ３ Or -NR １ (R ２ ) represents R １ and R ２ are each independently a hydrogen atom, a hydrocarbon group having 1 to 24 carbon atoms, an aminoalkyl group, or -R-Si(R') ｎ (OA) ３－ｎ The alkyl group D is a hydrocarbon group having 1 to 24 carbon atoms. ３ and Q ３ 2. The laminated optical film according to claim 1, wherein the compound is represented by the formula: wherein R represents an azide group, an amino group, an epoxy group, or an acryloyl group.

7. When the laminate smoothness of the film having a larger laminate smoothness arcmin value among the retardation film and the optical film is α, ０．９３≦α／β≦１．０５ The laminated optical film according to claim 1 , which satisfies the above.

8. The laminated optical film is a laminated optical film in which at least a retardation film and an optical film other than a polyvinyl alcohol film are laminated via a molecular adhesive layer, and a polarizing film is further laminated on at least one of the laminated optical films, When the laminate smoothness of the entire laminated optical film is β', β'<0.45 arcmin A laminated optical film comprising:

9. The laminated optical film according to claim 8 , wherein the optical film is a retardation film.

10. When the laminate smoothness of a film having a large laminate smoothness arcmin value among the retardation film, the optical film, and the polarizing film is defined as α', ０．９３≦α’／β’≦１．０５ The laminated optical film according to claim 8 , which satisfies the above.

11. An image display device comprising the laminated optical film according to claim 1 .

12. An image display device comprising the laminated optical film according to claim 8 .

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