Stacked optical films and image display devices

Abstract

To provide a laminated optical film including at least an acrylic film, which suppresses foreign-matter-induced bright spots even after humid durability testing, maintains superior visual characteristics, and ensures strong adhesion between the laminated optical films.SOLUTION: A laminated optical film includes at least an acrylic film and a first optical film laminated on each other with an adhesive layer interposed therebetween, wherein the adhesive layer is made of a layer of a cured product from an adhesive composition containing at least a polymerizable compound, wherein the acrylic film is in direct contact with the adhesive layer. The HSP distance between the acrylic film and the adhesive layer is 1.9 or more and 5.0 or less. The adhesive layer has an elastic modulus of 108 Pa or more and 3×109 Pa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated optical film in which at least an acrylic film and a first optical film are laminated with an adhesive layer in between. This laminated optical film can form image display devices such as mobile phones, car navigation systems, personal computer monitors, and televisions. [Background technology]

[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. The optical films used include polarizers and transparent resin films such as acrylic films.

[0003] Regarding acrylic films, there are concerns that the adhesive strength between the acrylic film and other optical films may not be sufficient when used as a laminated optical film, because the film surface contains almost no functional groups that can contribute to improving adhesion. In response to this, Patent Document 1 below describes an optical film laminate in which a (meth)acrylic resin layer and a thermoplastic resin film such as a cycloolefin resin film are bonded with sufficient adhesive strength using an active energy ray curable adhesive, resulting in a lightweight and thin film. The adhesive layer is formed by an active energy ray curable adhesive containing 2 to 35 parts by weight of a polymerizable monomer that dissolves the (meth)acrylic resin layer and 30 to 60 parts by weight of a polymerizable polyfunctional acrylate compound, with respect to 100 parts by weight of the total active energy ray curable compound containing a polymerizable monomer that dissolves the (meth)acrylic resin layer and a polymerizable polyfunctional acrylate compound. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-232251 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, in recent years, a durability test required for laminated optical films used in automotive applications is a humidified durability test, for example, one in which the film is exposed to an environment of 65°C and 95% humidity for 1000 hours. When the inventors of this invention conducted a detailed examination of the appearance of laminated optical films after such a humidified durability test, they found that bright spots originating from white, hazy foreign matter appeared, particularly at the edges of the laminated optical film, resulting in a product defect in terms of appearance characteristics. This phenomenon is observed for the first time after durability tests in high temperature and high humidity environments, and it was necessary to diligently investigate and resolve it.

[0006] The present invention was developed in view of the above circumstances, and aims to provide a laminated optical film comprising at least an acrylic film in which the generation of bright spots originating from foreign matter is suppressed even after a humidification durability test, has excellent appearance characteristics, and has excellent adhesive strength between laminated optical films. [Means for solving the problem]

[0007] The above problems can be solved by the following configuration. That is, the present invention is a laminated optical film in which at least an acrylic film and a first optical film are laminated with an adhesive layer in between, wherein the adhesive layer is formed of a cured layer of an adhesive composition containing at least a polymerizable compound, the acrylic film and the adhesive layer have a structure in which they are in direct contact, the HSP distance between the acrylic film and the adhesive layer is 1.9 or more and 5.0 or less, and the elastic modulus of the adhesive layer is 10 8 Pa or higher and 3 x 10 9 The present invention relates to a laminated optical film (1) characterized by having a Pa of less than or equal to Pa.

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

[0009] In the above laminated optical film (1) or (2), a laminated optical film (3) in which the thickness of the adhesive layer is 0.1 to 10 μm is preferable.

[0010] In any one of the above laminated optical films (1) to (3), a laminated optical film (4) in which a second optical film is further laminated via an adhesive layer on the surface of the first optical film opposite to the surface on which the acrylic film is laminated is preferable.

[0011] In any one of the above laminated optical films (1) to (4), a laminated optical film (5) in which the second optical film is a liquid crystal film or a retardation film is preferable.

[0012] In any one of the above laminated optical films (1) to (5), the adhesive composition contains a polymerizable compound A, and the polymerizable compound A has an HSP distance from the acrylic film of 0.0 or more and 4.0 or less. When the total amount of the polymerizable compounds contained in the adhesive composition is 100 parts by mass, a laminated optical film (6) in which the content of the polymerizable compound A is 20 parts by mass or more and 60 parts by mass or less is preferable.

[0013] In any one of the above laminated optical films (1) to (6), the adhesive composition contains a polymerizable compound B, and the polymerizable compound B is a compound having at least two or more polymerizable groups. When the total amount of the polymerizable compounds contained in the adhesive composition is 100 parts by mass, a laminated optical film (7) in which the content of the polymerizable compound B is 20 parts by mass or more and 50 parts by mass or less is preferable.

[0014] In the above laminated optical film (6) or (7), the adhesive composition contains a polymerizable compound C, and the polymerizable compound C has an HSP distance from the acrylic film of more than 4.0 and 8.0 or less. When the total amount of the polymerizable compounds contained in the adhesive composition is 100 parts by mass, a laminated optical film (8) in which the content of the polymerizable compound C is not more than the blending amount of the polymerizable compound A is preferable.

[0015] In any one of the laminated optical films (1) to (8) above, the adhesive composition contains a polymerizable compound D, and the polymerizable compound D is represented by the following general formula (1):

Chemical formula

[0016] In the laminated optical film (9) above, the adhesive composition contains a polymerizable compound E, the polymerizable compound E is a polymerizable compound containing a hydroxyl group, and when the content of the polymerizable compound D is 1, a laminated optical film (10) in which the content of the polymerizable compound E is 1 or more and 15 or less is preferable.

[0017] The present invention also relates to an image display device (11) including at least one of the laminated optical films (1) to (10) above.

Advantages of the Invention

[0018] As mentioned above, with regard to acrylic films, there are concerns that the adhesive strength may be insufficient when used in laminated optical films because the film surface contains almost no functional groups that can contribute to improving adhesive strength. One method for improving the adhesion between acrylic films and adhesive layers is to apply an easy-to-adhere adhesive, such as a water-based urethane resin, to the acrylic film to form an easy-to-adhere layer. However, due to process constraints, it is sometimes necessary to manufacture laminated optical films with a structure where the acrylic film and adhesive layer are in direct contact, without forming an easy-to-adhere layer on the acrylic film. In such cases, there are concerns that the adhesive strength may be insufficient due to the low interaction between the acrylic film and the adhesive layer.

[0019] Incidentally, laminated optical films used in automotive applications and other fields are required to have excellent appearance characteristics even after a humidification durability test in which they are exposed to an environment of 65°C and 95% humidity for 1000 hours. One component that adversely affects appearance characteristics is oxalate spotting, which occurs when oxalic acid present in the atmosphere forms salts during heating processes such as ovens and heating devices, drying processes, or film surface modification processes such as corona treatment, plasma treatment, and Itro treatment. Conventionally, oxalate spotting has been a problem in adhesive layers that come into contact with polarizers and contain metal components such as zinc, which cause oxalate spotting. However, as a result of the inventors' research, it has been found that deterioration of appearance characteristics due to oxalate spotting can also occur in adhesive layers that do not come into contact with polarizers, specifically in the adhesive layer that comes into direct contact with the acrylic film in this invention.

[0020] As described above, laminated optical films comprising an acrylic film have a unique challenge: because the acrylic film surface has almost no functional groups that can contribute to adhesion, it is difficult to increase the adhesion between the acrylic film and the adhesive layer while suppressing the generation of oxalic acid spots when the acrylic film is not treated with an easy-to-use adhesive containing water-based urethane resin, i.e., when the acrylic film and the adhesive layer are in direct contact. However, in the laminated optical film according to the present invention, the generation of bright spots originating from foreign matter is suppressed even after humidification durability testing, resulting in excellent appearance characteristics and excellent adhesion between the laminated optical films. The reason for these effects is not clear, but the following reasons are considered.

[0021] The laminated optical film according to the present invention is a laminated optical film in which at least an acrylic film and a first optical film are laminated with an adhesive layer in between, the adhesive layer is formed of a cured layer of an adhesive composition containing at least a polymerizable compound, and the acrylic film and the adhesive layer have a structure in which they are in direct contact. Furthermore, (i) the HSP distance between the acrylic film and the adhesive layer is 1.9 or more and 5.0 or less, and (ii) the elastic modulus of the adhesive layer is 10 8 Pa or higher and 3 x 10 9It is designed to be Pa or less. As described above, oxalic acid, a component that adversely affects appearance characteristics, can be mixed into the adhesive layer from the atmosphere during each manufacturing process. However, in the present invention, since it has the configuration described in (ii) above, the adhesive layer becomes sufficiently elastic, suppressing the mixing of oxalic acid into the adhesive layer and suppressing the occurrence of oxalic acid bright spots that cause deterioration of appearance characteristics. On the other hand, if the acrylic film and the adhesive layer are in direct contact, it is difficult to increase the adhesive strength between the acrylic film and the adhesive layer, and it is thought that this becomes even more difficult to improve the adhesive strength when the adhesive layer is made highly elastic. However, since the laminated optical film according to the present invention has the configuration described in (i) above, a compatible layer is formed between the acrylic film and the adhesive layer, and the adhesive strength is increased by the anchoring effect. As a result, in the laminated optical film according to the present invention, the occurrence of bright spots originating from foreign matter is suppressed even after the humidification durability test, and it has excellent appearance characteristics as well as excellent adhesive strength between the laminated optical films.

[0022] When the adhesive layer of the laminated optical film according to the present invention contains at least one of specific polymerizable compounds A to E, and especially when it contains polymerizable compounds A, B, D and / or E, the adhesion to the acrylic film or to the first optical film, or the effect of suppressing the generation and diffusion of oxalic acid spots is further enhanced. [Brief explanation of the drawing]

[0023] [Figure 1] This is an example of a schematic cross-sectional view of a laminated optical film according to one embodiment of the present invention. [Modes for carrying out the invention]

[0024] Figure 1 shows an example of a schematic cross-sectional view of a laminated optical film according to one embodiment of the present invention. In this embodiment, the laminated optical film 10 has an acrylic film 1 and a first optical film 2 laminated together via an adhesive layer 3. There is no intervening layer such as an easy-adhesion layer between the acrylic film 1 and the adhesive layer 3, and the acrylic film 1 and the adhesive layer 3 are in direct contact. Details of the acrylic film 1, the first optical film 2, and the adhesive layer 3 will be described separately. In this embodiment, the laminated optical film 10 further has a triacetylcellulose film 6, which is a transparent protective film, laminated on the side of the acrylic film 1 opposite to the side on which the first optical film 2 is laminated, via a water-based adhesive layer 7. A second optical film 4 is further laminated on the side of the first optical film 2 opposite to the side on which the acrylic film 1 is laminated, via an adhesive layer 5. Details of the adhesive layer 5 and the second optical film 4 will be described separately. In this embodiment, the second optical film 4 is bonded to an image display device (not shown in Figure 1) via an adhesive layer 8 on the side of the second optical film 4 opposite to the side on which the first optical film 2 is laminated. Each configuration will be described below.

[0025] <Acrylic film> Acrylic film contains (meth)acrylic resin. (Meth)acrylic resin film can be obtained, for example, by extrusion molding of a molding material containing a resin component mainly composed of (meth)acrylic resin.

[0026] The (meth)acrylic resin described above has a glass transition temperature (Tg) of preferably 70°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, and particularly preferably 120°C or higher. The (meth)acrylic resin film described above can be made highly durable by containing a (meth)acrylic resin with a glass transition temperature (Tg) of 70°C or higher as its main component. The upper limit of the Tg of the (meth)acrylic resin described above is not particularly limited, but from the viewpoint of moldability and other factors, it is preferably 170°C or lower.

[0027] Any suitable (meth)acrylic resin can be used as the (meth)acrylic resin mentioned above. For example, poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-(meth)acrylic acid ester copolymers, methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers, methyl (meth)acrylic acid-styrene copolymers (MS resin, etc.), and polymers having alicyclic hydrocarbon groups (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylic acid copolymer, etc.). Preferably, poly(meth)acrylic acid C1-6 alkyl such as polymethyl (meth)acrylate is used. More preferably, a methyl methacrylate resin having methyl methacrylate as the main component (50-100% by weight, preferably 70-100% by weight) is used.

[0028] In the present invention, in terms of having high heat resistance, high transparency, and high mechanical strength, the (meth)acrylic resin is preferably a (meth)acrylic resin having a glutaric acid anhydride structure, a (meth)acrylic resin having a lactone ring structure, or a (meth)acrylic resin having a glutarimide structure.

[0029] Examples of (meth)acrylic resins having a glutaric acid anhydride structure include those described in Japanese Patent Publication No. 2006-283013, Japanese Patent Publication No. 2006-335902, Japanese Patent Publication No. 2006-274118, and others.

[0030] Examples of (meth)acrylic resins having a lactone ring structure include those described in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084.

[0031] Examples of (meth)acrylic resins having a glutarimide structure include those described in Japanese Patent Publication No. 2006-309033, Japanese Patent Publication No. 2006-317560, Japanese Patent Publication No. 2006-328329, Japanese Patent Publication No. 2006-328334, Japanese Patent Publication No. 2006-337491, Japanese Patent Publication No. 2006-337492, Japanese Patent Publication No. 2006-337493, Japanese Patent Publication No. 2006-337569, Japanese Patent Publication No. 2007-009182, and others.

[0032] The content of the above-mentioned (meth)acrylic resin in the (meth)acrylic resin 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 (meth)acrylic resin in the (meth)acrylic resin film is less than 50% by weight, the high heat resistance and high transparency inherent to the (meth)acrylic resin may not be fully reflected.

[0033] The content of the above-mentioned (meth)acrylic resin in the molding material used when molding the (meth)acrylic resin 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 (meth)acrylic resin in the molding material used when molding the (meth)acrylic resin film is less than 50% by weight, the high heat resistance and high transparency inherent in the (meth)acrylic resin may not be fully reflected.

[0034] (Meth)acrylic resin films may contain other thermoplastic resins in addition to the (meth)acrylic resins mentioned above. Examples of other thermoplastic resins include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly(4-methyl-1-pentene); halogenated vinyl polymers such as vinyl chloride, vinylidene chloride, and chlorinated vinyl resin; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene block copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon 6, nylon 66, and nylon 610; polyacetal; polycarbonate; polyphenylene oxide; polyphenylene sulfide; polyether ether ketone; polysulfone; polyethersulfone; polyoxybenzyne; polyamide-imide; and rubbery polymers such as ABS resin and ASA resin blended with polybutadiene rubber and acrylic rubber.

[0035] The content of other thermoplastic resins in the (meth)acrylic resin film is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, even more preferably 0 to 30% by weight, and particularly preferably 0 to 20% by weight.

[0036] (Meth)acrylic resin films may contain additives. Examples of additives include: antioxidants such as hindered phenol, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; ultraviolet absorbers such as phenyl salicylate, (2,2'-hydroxy-5-methylphenyl)benzotriazole, and 2-hydroxybenzophenone; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic and inorganic fillers; resin modifiers; organic and inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants; and phase difference reducing agents.

[0037] The additive content in the (meth)acrylic resin film is preferably 0 to 5% by weight, more preferably 0 to 2% by weight, and even more preferably 0 to 0.5% by weight.

[0038] The method for producing a (meth)acrylic resin film is not particularly limited, but for example, the (meth)acrylic resin and other polymers or additives can be thoroughly mixed using any suitable mixing method to form a thermoplastic resin composition beforehand, and then this can be formed into a film. Alternatively, the (meth)acrylic resin and other polymers or additives can be prepared as separate solutions, mixed to form a homogeneous mixture, and then formed into a film.

[0039] To produce the above thermoplastic resin composition, the above film raw materials are pre-blended in any suitable mixer, such as an omni-mixer, and then the resulting mixture is extruded and kneaded. In this case, the mixer used for extrusion kneading is not particularly limited, and any suitable mixer can be used, such as an extruder like a single-screw extruder or twin-screw extruder, or a pressure kneader.

[0040] Examples of the above-mentioned film forming methods include any suitable film forming method such as solution casting, melt extrusion, calendering, and compression molding. Of these film forming methods, solution casting and melt extrusion are preferred.

[0041] Examples of solvents used in the above solution casting method (solution casting method) include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; dimethylformamide; and dimethyl sulfoxide. These solvents may be used individually or in combination of two or more.

[0042] Examples of equipment for performing the above-mentioned solution casting method (solution casting method) include drum-type casting machines, band-type casting machines, and spin coaters.

[0043] Examples of the melt extrusion methods mentioned above include the T-die method and the inflation method. The molding temperature is preferably 150 to 350°C, more preferably 200 to 300°C.

[0044] When forming a film using the T-die method described above, a T-die is attached to the tip of a known single-screw or twin-screw extruder, and the extruded film is wound up to obtain a roll of film. In this case, by appropriately adjusting the temperature of the winding roll and applying stretching in the extrusion direction, uniaxial stretching is also possible. Furthermore, by stretching the film in a direction perpendicular to the extrusion direction, simultaneous biaxial stretching, sequential biaxial stretching, etc., can also be performed.

[0045] The (meth)acrylic resin film may be either an unstretched film or a stretched film. If it is a stretched film, it may be either a uniaxially oriented film or a biaxially oriented film. If it is a biaxially oriented film, it may be either a simultaneously biaxially oriented film or a sequentially biaxially oriented film. When biaxially oriented, mechanical strength is improved and film performance is enhanced. By mixing the (meth)acrylic resin film with other thermoplastic resins, the increase in phase difference can be suppressed even when stretched, and optical isotropy can be maintained.

[0046] The stretching temperature is preferably near the glass transition temperature of the thermoplastic resin composition used as the film raw material. Specifically, it is preferably in the range of (glass transition temperature - 30°C) to (glass transition temperature + 100°C), and more preferably in the range of (glass transition temperature - 20°C) to (glass transition temperature + 80°C). If the stretching temperature is below (glass transition temperature - 30°C), a sufficient stretching ratio may not be obtained. Conversely, if the stretching temperature exceeds (glass transition temperature + 100°C), flow of the resin composition may occur, making stable stretching impossible.

[0047] The stretch ratio, defined by area ratio, is preferably 1.1 to 25 times, and more preferably 1.3 to 10 times. If the stretch ratio is less than 1.1 times, it may not lead to an improvement in toughness associated with stretching. If the stretch ratio exceeds 25 times, it may not be possible to observe the effect of increasing the stretch ratio.

[0048] The stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min, in one direction. If the stretching speed is less than 10% / min, it will take a long time to obtain a sufficient stretching ratio, which may increase manufacturing costs. If the stretching speed exceeds 20,000% / min, the stretched film may break or other damage may occur.

[0049] (Meth)acrylic resin films can be subjected to heat treatment (annealing) after stretching to stabilize their optical isotropy and mechanical properties. Any appropriate heat treatment conditions can be adopted.

[0050] The thickness of the (meth)acrylic resin film is preferably 20 to 60 μm, more preferably 20 to 30 μm. If the thickness is less than 20 μm, not only will the strength decrease, but there is also a risk of increased crimping when durability testing of the laminated optical film is performed. If the thickness exceeds 60 μm, there is a risk of decreased transparency.

[0051] The laminated optical film according to the present invention has an acrylic film and a first optical film laminated with an adhesive layer in between, and the acrylic film and the adhesive layer are in direct contact. In other words, the acrylic film does not have an easy-adhesion layer. However, a surface modification treatment may be performed on the surface of the acrylic film that is in contact with the adhesive layer. Examples of surface modification treatments include corona treatment, plasma treatment, and Itro treatment, with corona treatment being particularly preferred.

[0052] <First Optical Film> The laminated optical film according to the present invention comprises at least an acrylic film and a first optical film laminated with an adhesive layer in between. The first optical film is preferably a liquid crystal film or a phase difference film. Examples of liquid crystal films include an orientation film of a liquid crystal polymer and a film in which an orientation layer of a liquid crystal polymer is supported. Examples of phase difference films include a phase difference film having a front phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. The phase difference film may be a birefringent film obtained by uniaxial or biaxial stretching of a polymer material, an orientation film of a liquid crystal polymer, or a film in which an orientation layer of a liquid crystal polymer is supported. The thickness of the liquid crystal film and the phase difference film is not particularly limited, but is generally around 1 to 150 μm.

[0053] As for the phase difference film, the following formulas (1) to (3): 0.70 <Re

[0450] / Re

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

[0450] and Re

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

[0054] <Adhesive layer> The laminated optical film according to the present invention comprises at least an acrylic film and a first optical film laminated with an adhesive layer in between. The acrylic film and the adhesive layer are in direct contact. In other words, there is no easy-adhesion layer containing water-based urethane resin or the like between the acrylic film and the adhesive layer.

[0055] The laminated optical film according to the present invention has the following characteristics in the adhesive layer. (i) The HSP distance between the acrylic film and the adhesive layer is 1.9 or greater and 5.0 or less. (ii) The elastic modulus of the adhesive layer is 10 8 Pa or higher and 3 x 10 9 It is below Pa. With respect to (i) above, more preferably, the HSP distance between the acrylic film and the adhesive layer is 1.9 or more and 4.9 or less.

[0056] (Method for calculating solubility parameters (HSP distance)) In this invention, the solubility parameter (HSP distance) of the adhesive layer is calculated using Hansen's method [using HSPiP version 5.4.04 calculation software], that is, the Hansen solubility parameter, a value published by Charles M. Hansen in 1967, used to predict the solubility of a substance.

[0057] The Hansen solubility parameter consists of the following three parameters: • δD: Energy due to intermolecular dispersion forces • δP: Energy due to intermolecular dipole interaction • δH: Energy due to intermolecular hydrogen bonding These three parameters can be considered as coordinates in three-dimensional space. The affinity between two materials (for example, an acrylic film and an adhesive layer) can be evaluated by the distance between the two HSPs (HSP distance), and a smaller HSP distance between the two materials indicates greater affinity.

[0058] The HSP distance calculation formula used as an indicator in this study is the value obtained by substituting the three Hansen components of the two substances into the following formula. [Mathematics 1] HSP distance=√(4×(δD1-δD2)^2+2×(δP1-δP2)^2+2×(δH1-δH2)^2)

[0059] The adhesive layer is described in detail below. The adhesive layer is formed by a cured layer of an adhesive composition containing at least a polymerizable compound, and is particularly preferably formed by a cured layer of an active energy ray curable adhesive composition such as electron beam curable, ultraviolet curable, or visible light curable. The thickness of the adhesive layer after drying is preferably 0.1 μm to 10 μm, and more preferably 0.5 μm to 5 μm, from the viewpoint of improving the appearance characteristics and adhesive strength of the laminated optical film. Active energy ray curable adhesive compositions can be classified into radical polymerization curable adhesive compositions and cationic polymerization adhesive compositions. 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.

[0060] Examples of polymerizable compounds that constitute a radical polymerization-curable adhesive composition include radical polymerizable compounds. Examples of radical polymerizable compounds include compounds having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acryloyl 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. As these radical polymerizable compounds, for example, compounds having a (meth)acryloyl group are preferred. In this invention, (meth)acryloyl means an acryloyl group and / or a methacryloyl group, and "(meth)" has the same meaning hereafter.

[0061] Examples of monofunctional radical polymerizable compounds include (meth)acrylamide derivatives having a (meth)acrylamide group. (Meth)acrylamide derivatives are preferred for ensuring adhesion to polarizers and various transparent protective films, and for their fast polymerization rate and excellent productivity. 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-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-methylol-N-propane(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.

[0062] Among the (meth)acrylamide derivatives mentioned above, N-hydroxyalkyl group-containing (meth)acrylamide derivatives are preferred from the viewpoint of adhesion to polarizers and various transparent protective films. Examples of monofunctional radical polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, examples include alkyl esters of (meth)acrylic acid (with 1-20 carbon atoms), such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0063] Furthermore, the (meth)acrylic acid derivatives include, for example, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-ylmethyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyl acrylate. Examples include polycyclic (meth)acrylates such as methyl (meth)acrylate and dicyclopentanyl (meth)acrylate; and alkoxy group or phenoxy group-containing (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, and alkylphenoxy polyethylene glycol (meth)acrylate.

[0064] Furthermore, the (meth)acrylic acid derivatives include hydroxyalkyl( )acrylates such as 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 8-hydroxyoctyl(meth)acrylate, 10-hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate, etc. Hydroxyl group-containing (meth)acrylates such as meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate; epoxy group-containing (meth)acrylates such as glycidyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl(meth)acrylate, 2,2,2-trifluoroethyl(meth)acrylate Halogen-containing (meth)acrylates such as tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate Examples include acrylates, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, and other oxetane group-containing (meth)acrylates; heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; and hydroxypivalate neopentyl glycol (meth)acrylic acid adducts and p-phenylphenol (meth)acrylate.

[0065] Furthermore, examples of monofunctional radical polymerizable compounds include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0066] Examples of monofunctional radical polymerizable compounds include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and nitrogen-containing heterocyclic vinyl monomers such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

[0067] Furthermore, as a monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. A radical polymerizable compound having an active methylene group is a compound that has an active double bond group such as a (meth)acrylic group at its terminal or in the molecule, and also has an active methylene group. Examples of active methylene groups include an acetoacetyl group, an alkoxymalonyl group, or a cyanoacetyl group. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of radical polymerizable compounds having an active methylene group include acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; 2-ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, and N-(2-acetoacetylaminoethyl)acrylamide. The radical polymerizable compound having an active methylene group is preferably an acetoacetoxyalkyl (meth)acrylate.

[0068] In the present invention, it is preferable that the adhesive composition contains polymerizable compound A. Polymerizable compound A has an HSP distance of 0.0 or more and 4.0 or less from the acrylic film, and when the total amount of polymerizable compound contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound A is preferably 20 parts by mass or more and 60 parts by mass or less, and more preferably 30 parts by mass or more and 40 parts by mass or less. In the present invention, the "HSP distance between the acrylic film and the polymerizable compound" was calculated based on the HSP value of the acrylic film (δD: 18.5, δP: 10.9, δH: 7.7). Among the monofunctional radical polymerizable compounds mentioned above, the following are examples of polymerizable compound A. Vinylmethyloxazolidinone (HSP distance to acrylic film: 3.2), N-acryloylmorpholine (HSP distance to acrylic film: 1.9), N-isopropylacrylamide (HSP distance to acrylic film: 3.2), N-ethylacrylamide (HSP distance to acrylic film: 3.3), N-dimethylacrylamide (HSP distance to acrylic film: 2.8), N-vinylpyrrolidone (HSP distance to acrylic film: 3.1). The adhesive composition used in the present invention is preferable because the polymerizable compound A is included, thereby increasing the adhesion between the acrylic film and the adhesive layer and improving the adhesive strength.

[0069] Furthermore, in the present invention, it is preferable that the adhesive composition contains polymerizable compound C. Polymerizable compound C has an HSP distance from the acrylic film that is greater than 4.0 and 8.0 or less, and when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, it is preferable that the content of polymerizable compound C is less than or equal to the amount of polymerizable compound A, and more preferably 0 parts by mass or more and less than or equal to the amount of polymerizable compound A. The presence of polymerizable compound C in the adhesive composition used in the present invention is preferable because it improves the adhesive strength under humidified reliability testing. In particular, from the viewpoint of improving the adhesive strength under humidified reliability testing, when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, it is more preferable that the content of polymerizable compound C is less than or equal to the amount of polymerizable compound A, and more preferably 10 to 30 parts by mass. Examples of polymerizable compound C include the following monofunctional radical polymerizable compounds. 4-Hydroxybutyl acrylate acrylic (HSP distance to film 6.4), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (HSP distance to acrylic film 7.2), N (HSP distance to acrylic film 6.4), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (HSP distance to film 7.2), diethylacrylamide (HSP distance to film 5.9), t-butylcyclohexyl acrylate (HSP distance to film 5.4), ω-carboxypolycaprolactone (n=2) monoacrylate (HSP distance to film 7.1), phenoxydiethylene glycol acrylate (HSP distance to film 6.5), phenoxybenzyl acrylate (HSP distance to film 7.8), phenoxyethyl acrylate (HSP distance to film 6.3).

[0070] Furthermore, in the present invention, it is preferable that the adhesive composition contains polymerizable compound D. Polymerizable compound D is defined by the following general formula (1): [ka] A compound represented by (where X is a reactive group, Y is an alkylene group having 1 to 12 carbon atoms which may have a branched chain, or a phenylene group which may have a substituent, and R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group, or a heterocyclic group). When the total amount of the polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of the polymerizable compound D is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 5 parts by mass or less. Since the adhesive composition used in the present invention contains the polymerizable compound D, the adhesive strength between the acrylic film and the adhesive layer is increased, which is preferable for improving the adhesive force.

[0071] In the compound represented by the general formula (1), examples of the aliphatic hydrocarbon group include a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkyl group having 3 to 20 carbon atoms which may have a substituent, and an alkenyl group having 2 to 20 carbon atoms. Examples of the aryl group include a phenyl group having 6 to 20 carbon atoms which may have a substituent, a naphthyl group having 10 to 20 carbon atoms which may have a substituent, etc. Examples of the heterocyclic group include a 5-membered or 6-membered group which may have a substituent and contains at least one heteroatom. These may be linked to each other to form a ring. In the general formula (1), R 1 and R 2 are preferably a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom.

[0072] The X in the compound represented by general formula (1) is a reactive group, a functional group that can react with the curable components constituting the adhesive layer, and examples include hydroxyl groups, amino groups, aldehyde groups, carboxyl groups, vinyl groups, (meth)acrylic groups, styryl groups, (meth)acrylamide groups, vinyl ether groups, epoxy groups, oxetane groups, α,β-unsaturated carbonyl groups, mercapto groups, halogen groups, and the like. When the curable 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 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.

[0073] Preferred specific examples of compounds represented by general formula (1) include the following compounds (1a) to (1d). Note that R in general formulas (1a) and (1b) 3 This is either a hydrogen atom or a methyl group. [ka]

[0074] In addition to the compounds exemplified above, examples of compounds represented by general formula (1) include esters of (meth)acrylates and boric acid, such as esters of hydroxyethyl acrylamide and boric acid, esters of methylol acrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

[0075] Furthermore, in the present invention, it is preferable that the adhesive composition contains polymerizable compound E. Polymerizable compound E is a polymerizable compound containing a hydroxyl group, and when the content of polymerizable compound D is taken as 1, the content of polymerizable compound E is preferably 1 or more and 15 or less, and more preferably 5 parts by mass or more and 12 parts by mass or less. Examples of polymerizable compound D 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, as well as hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. The presence of polymerizable compound E in the adhesive composition used in the present invention is preferable because it increases the adhesion between the acrylic film and the adhesive layer, thereby improving adhesive strength.

[0076] Examples of polyfunctional radical polymerizable compounds having two or more polymerizable functional groups include tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, and neopentyl glycol. Examples include esters of (meth)acrylic acid with polyhydric alcohols such as di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclic trimethylolpropane formal(meth)acrylate, dioxaneglycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and EO-modified diglycerin tetra(meth)acrylate, as well as 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Aronics M-220 (manufactured by Toagosei Co., Ltd.), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), etc. In addition, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and various (meth)acrylate monomers may be used as needed.

[0077] In the present invention, it is preferable that the adhesive composition contains polymerizable compound B. Polymerizable compound B is a compound having at least two polymerizable groups, and when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound B is preferably 20 parts by mass or more and 50 parts by mass or less, and more preferably 30 parts by mass or more and 40 parts by mass or less. Examples of polymerizable compound B include the polyfunctional radical polymerizable compounds mentioned above. By containing polymerizable compound B in the adhesive composition used in the present invention, the adhesive layer becomes sufficiently elastic, the incorporation of oxalic acid into the adhesive layer is suppressed, and the occurrence of oxalic acid spots that cause deterioration of appearance characteristics can be suppressed.

[0078] 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, acrylic oligomers obtained by polymerizing (meth)acrylic monomers. By including acrylic oligomers in the adhesive composition, curing shrinkage when the composition is irradiated and cured with active energy rays can be reduced, and interfacial stress between the adhesive layer and adherends such as polarizers and optical films can be reduced. As a result, a decrease in the adhesion between the adhesive layer and adherends can be suppressed.

[0079] For active energy ray curing adhesives, low viscosity is preferable when considering workability and uniformity during coating; therefore, acrylic oligomers obtained by polymerizing (meth)acrylic monomers are also preferably low viscosity. Acrylic oligomers that are low viscosity and can prevent curing shrinkage of the adhesive layer are preferably those with a weight-average molecular weight (Mw) of 15,000 or less, more preferably 10,000 or less, and particularly preferably 5,000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the cured 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,Alkyl esters of (meth)acrylic acid (C1-C20) such as 2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate, and also, for example, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl ( (meth)acrylates, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (e.g., 2,2,2-trifluoroethyl (meth)acrylate, 2,2Examples include 2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc., and alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate). These (meth)acrylates can be used alone or in combination of two or more types. Specific examples of acrylic oligomers (E) include "ARUFON" from Toagosei Co., Ltd., "Actflow" from Soken Chemical Co., Ltd., and "JONCRYL" from BASF Japan.

[0080] The amount of acrylic oligomer blended is preferably 15 parts by weight or less per 100 parts by weight of the total amount of monomer components in the adhesive composition. If the acrylic oligomer content in the composition is too high, the reaction rate when the composition is irradiated with active energy rays will decrease sharply, which may result in poor curing. On the other hand, in order to sufficiently suppress curing shrinkage of the adhesive layer, it is preferable to contain 3 parts by weight or more of acrylic oligomer in the composition.

[0081] When using radical polymerizable compounds, the photopolymerization initiator is appropriately selected based on the active energy ray. When curing is performed with 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-morpholinopropane-1; benzioin methyl ether, benzioin ethyl ether, benzoin isopropyl ether, and Examples include benzoin ether compounds such as benzoin butyl ether and anisoin methyl ether; aromatic ketal compounds such as benzyldimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

[0082] The amount of the photopolymerization initiator is 20% by weight or less, when the total amount of the active energy ray curable 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.

[0083] Furthermore, when the curable adhesive for laminated optical films of the present invention is used as a visible light curable type containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator that is highly sensitive to light of 380 nm or higher. Photopolymerization initiators highly sensitive to light of 380 nm or higher will be described later.

[0084] The aforementioned photopolymerization initiator is a compound represented by the following general formula (1);

[0085] [ka] (In the formula, R 1 and R 2 R represents -H, -CH2CH3, -iPr, or Cl. 1 and R 2 It is preferable to use the compound represented by general formula (1) alone (which may be the same or different) or to use it in combination with a photopolymerization initiator that is highly sensitive to light of 380 nm or higher, as described later. When the compound represented by general formula (1) is used, the adhesion is superior to when the photopolymerization initiator that is highly sensitive to light of 380 nm or higher is used alone. Among the compounds represented by general formula (1), R 1 and R 2 Diethylthioxanthone, in which is -CH2CH3, is particularly preferred. The composition ratio of the compound represented by general formula (1) 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, based on 100 parts by weight of the total amount of curable components.

[0086] Furthermore, it is preferable to add polymerization initiators as needed. Examples of polymerization initiators include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate, with ethyl 4-dimethylaminobenzoate being particularly preferred. When using polymerization initiators, the amount added is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, per 100 parts by weight of the total amount of curable components.

[0087] Furthermore, known photopolymerization initiators can be used in combination as needed. Since transparent protective films with UV absorption ability do not transmit light below 380 nm, it is preferable to use a photopolymerization initiator that is highly sensitive to light above 380 nm. Specifically, examples include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium.

[0088] In particular, as a photopolymerization initiator, in addition to the photopolymerization initiator of general formula (1), a compound represented by the following general formula (2);

[0089] [ka] (In the formula, R 3 , R 4 and R 5 R represents -H, -CH3, -CH2CH3, -iPr, or Cl. 3 , R 4 and R5 It is preferable to use compounds that are the same or different. As compounds represented by general formula (2), commercially available products such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (trade name: Omnirad819, manufacturer: IGM Resins BV) and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (trade name: Omnirad907, manufacturer: IGM Resins BV) can be suitably used. In addition, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name: Omnirad369, manufacturer: IGM Resins BV) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (trade name: Omnirad379, manufacturer: IGM Resins BV) are preferred due to their high sensitivity.

[0090] 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 "DAROCUR1173", manufactured by BASF), 1-hydroxycyclohexylphenyl ketone (trade name "IRGACURE184", manufactured by BASF), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name "IRGACURE2959", manufactured by BASF), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one (trade name "IRGACURE127", manufactured by BASF). 1-hydroxycyclohexylphenyl ketone is particularly preferred because of its excellent solubility in adhesive layers with a high concentration of component A.

[0091] In the present invention, a cationic polymerizable adhesive composition may be used as the adhesive composition that serves as the raw material for the adhesive layer of the laminated optical film. Cationic polymerizable compounds used in cationic polymerizable adhesive compositions are classified into monofunctional cationic polymerizable compounds having one cationic polymerizable functional group in the molecule, and polyfunctional cationic polymerizable compounds having two or more cationic polymerizable functional groups in the molecule. Monofunctional cationic polymerizable compounds have relatively low liquid viscosity, so including them in a resin composition can reduce the liquid viscosity of the resin composition. Furthermore, monofunctional cationic polymerizable compounds often have functional groups that exhibit various functions, and including them in a cationic polymerizable adhesive composition can exhibit various functions in the cationic polymerizable adhesive composition and / or the cured product of the cationic polymerizable adhesive composition. Polyfunctional cationic polymerizable compounds are preferable to include in a cationic polymerizable adhesive composition because they can cause three-dimensional crosslinking of the cured product of the cationic polymerizable adhesive composition. The ratio of monofunctional cationic polymerizable compounds to polyfunctional cationic polymerizable compounds is preferably in the range of 10 to 1000 parts by weight of polyfunctional cationic polymerizable compounds per 100 parts by weight of monofunctional cationic polymerizable compounds. Examples of cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Examples of compounds having epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. The cationic polymerizable adhesive composition of the present invention is particularly preferably composed of an alicyclic epoxy compound because it exhibits excellent curability and adhesion. Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, caprolactone-modified, trimethylcaprolactone-modified, and valerolactone-modified 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 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 are preferable to include in cationic polymerizable adhesive compositions because they improve the curability of the composition and reduce its liquid viscosity. Examples of compounds containing 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, and Aronoxetane OXT-212 (all manufactured by Toagosei Co., Ltd.) are commercially available. Compounds having vinyl ether groups are preferable to include because they have the effect of improving the curability of cationic polymerizable adhesive compositions and reducing the liquid viscosity of the compositions. Examples of compounds having vinyl ether groups 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.

[0092] Cationic polymerizable adhesive compositions contain at least one compound selected from the epoxy group-containing compounds, oxetanyl group-containing compounds, and vinyl ether group-containing compounds described above as curable components, all of which cure by cationic polymerization; therefore, a photocationic polymerization initiator is included. This photocationic polymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, and electron beams, and initiates the polymerization reaction of epoxy groups and oxetanyl groups. As the photocationic polymerization initiator, the photoacid generator described later is preferably used. Furthermore, when using a cationic polymerizable adhesive composition that is curable with visible light, it is preferable to use a photocationic polymerization initiator that is particularly sensitive to light of 380 nm or higher. However, since photocationic polymerization initiators are generally compounds that show maximum absorption around 300 nm or shorter wavelengths, by incorporating a photosensitizer that shows maximum absorption in a longer wavelength range, specifically light with wavelengths longer than 380 nm, it is possible to stimulate light of this wavelength range and promote the generation of cationic species or acids from the photocationic polymerization initiator. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organosulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducible dyes. Two or more of these may be used in combination. Anthracene compounds are particularly preferred due to their excellent photosensitizing effect, and specific examples include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.). The photosensitizer content is preferably 0.1% to 5% by weight, and more preferably 0.5% to 3% by weight.

[0093] The laminated optical film 10 shown in Figure 1 further has a transparent protective film, triacetylcellulose film 6, laminated on the opposite side of the acrylic film 1 from the side where the first optical film 2 is laminated, via a water-based adhesive layer 7. Furthermore, a second optical film 4 is laminated on the opposite side of the first optical film 2 from the side where the acrylic film 1 is laminated, via an adhesive layer 5.

[0094] <Adhesive layer> The adhesive forming the adhesive layer is not particularly limited, but for example, adhesives 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.

[0095] 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.

[0096] <Second Optical Film> In the present invention, the second optical film is preferably a liquid crystal film or a phase difference film. The same liquid crystal film and phase difference film exemplified for the first optical film can be suitably used.

[0097] The laminated optical film according to the present invention may also include the following optical films in addition to the acrylic film, the first optical film, and the second optical film.

[0098] The laminated optical film according to the present invention may also include a polarizer as another optical film. Polyvinyl alcohol or its derivatives are used as the material for the polyvinyl alcohol-based film applied to the polarizer. Examples of polyvinyl alcohol derivatives include polyvinyl formal and polyvinyl acetal, as well as those modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, their alkyl esters, and acrylamide. Generally, polyvinyl alcohol with a degree of polymerization of about 1000 to 10000 and a degree of saponification of about 80 to 100 mol% is used.

[0099] Polyvinyl alcohol-based films may contain additives such as plasticizers. Examples of plasticizers include polyols and their condensates, such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of plasticizer used is not particularly limited, but 20% by weight or less in the polyvinyl alcohol-based film is preferred.

[0100] In the manufacture of polarizers, the polyvinyl alcohol-based film is subjected to a dyeing process in which it is dyed with iodine, and a stretching process in which the polyvinyl alcohol-based film is stretched in at least one direction. Generally, a method is employed in which the polyvinyl alcohol-based film is subjected to a series of processes including swelling, dyeing, crosslinking, stretching, washing, and drying.

[0101] The swelling process is carried out, for example, by immersing the polyvinyl alcohol-based film in a swelling bath (water bath). This treatment cleans dirt and blocking agents from the surface of the polyvinyl alcohol-based film and prevents uneven dyeing by swelling the film. Glycerin, potassium iodide, etc. may be added to the swelling bath as appropriate. The temperature of the swelling bath is usually around 20 to 60°C, and the immersion time in the swelling bath is usually around 0.1 to 10 minutes.

[0102] The dyeing process is carried out, for example, by immersing a polyvinyl alcohol-based film in an iodine solution. The iodine solution is usually an aqueous iodine solution containing iodine and potassium iodide as a solubilizer. The iodine concentration is usually about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The potassium iodide concentration is usually about 0.01 to 10% by weight, preferably 0.02 to 8% by weight.

[0103] In the iodine staining process, the temperature of the iodine solution is usually around 20 to 50°C, preferably 25 to 40°C. The immersion time is usually around 10 to 300 seconds, preferably 20 to 240 seconds. When performing the iodine staining treatment, it is preferable to adjust conditions such as the concentration of the iodine solution, the immersion temperature of the polyvinyl alcohol film in the iodine solution, and the immersion time so that the iodine content and potassium content in the polyvinyl alcohol film are within the aforementioned ranges.

[0104] The crosslinking process is carried out, for example, by immersing an iodine-stained polyvinyl alcohol-based film in a treatment bath containing a crosslinking agent. Any suitable crosslinking agent can be used. Specific examples of crosslinking agents include boric acid, boron compounds such as borax, glyoxal, and glutaraldehyde. These can be used alone or in combination. Water is generally used as the solvent in the crosslinking bath solution, but an appropriate amount of an organic solvent compatible with water may be added. The crosslinking agent is usually used in a ratio of 1 to 10 parts by weight per 100 parts by weight of solvent. It is desirable that the crosslinking bath solution further contain auxiliary agents such as iodide. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. The temperature of the crosslinking bath is usually around 20 to 70°C, preferably 40 to 60°C. The immersion time in the crosslinking bath is usually around 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

[0105] The stretching process is a process in which the polyvinyl alcohol-based film is stretched in at least one direction. Generally, the polyvinyl alcohol-based film is uniaxially stretched in the transport direction (longitudinal direction). The stretching method is not particularly limited, and either wet stretching or dry stretching can be used. When wet stretching is used, the polyvinyl alcohol-based film is stretched to a predetermined magnification in the treatment bath. As the solution for the stretching bath, a solution containing various compounds necessary for the treatment is preferably used in a solvent such as water or an organic solvent (e.g., ethanol). Examples of dry stretching methods include the inter-roll stretching method, the heated roll stretching method, and the compression stretching method. In the manufacture of polarizers, the stretching process may be carried out at any stage. Specifically, it may be carried out simultaneously with swelling, dyeing, and crosslinking, or before or after each of these processes. Furthermore, stretching may be carried out in multiple stages. The cumulative stretching magnification of the polyvinyl alcohol-based film is usually 5 times or more, preferably around 5 to 7 times.

[0106] In the present invention, it is preferable that the polarizer contains a metal component that can become a divalent metal cation in water, more preferably magnesium, calcium, copper, or zinc, and particularly preferably zinc. The inclusion of zinc in the polarizer tends to suppress the decrease in transmittance and hue degradation of the laminated optical film after heating tests. When the polarizer contains zinc, the zinc content in the polarizer is preferably 0.002 to 2% by weight, and more preferably 0.01 to 1% by weight.

[0107] In the present invention, it is preferable that the polarizer contains sulfate ions. The presence of sulfate ions in the polarizer tends to suppress the decrease in transmittance of the laminated optical film after the heating test. When the polarizer contains sulfate ions, the sulfate ion content in the polarizer is preferably 0.02 to 0.45% by weight, more preferably 0.05 to 0.35% by weight, and even more preferably 0.1 to 0.25% by weight. The sulfate ion content in the polarizer is calculated from the sulfur atom content.

[0108] In order to include zinc in the polarizer, it is preferable to perform a zinc impregnation treatment during the polarizer manufacturing process. Furthermore, in order to include sulfate ions in the polarizer, it is preferable to perform a sulfate ion treatment during the polarizer manufacturing process.

[0109] The zinc impregnation treatment is carried out, for example, by immersing a polyvinyl alcohol-based film in a zinc salt solution. Suitable zinc salts include zinc halides such as zinc chloride and zinc iodide, and inorganic salt compounds such as aqueous solutions of zinc sulfate and zinc acetate. Various zinc complex compounds may also be used for the zinc impregnation treatment. Furthermore, it is preferable to use an aqueous solution containing potassium ions and iodide ions, such as potassium iodide, as this facilitates zinc ion impregnation. The potassium iodide concentration in the zinc salt solution is preferably about 0.5 to 10% by weight, and more preferably 1 to 8% by weight.

[0110] Sulfate ion treatment is carried out, for example, by immersing a polyvinyl alcohol-based film in an aqueous solution containing a metal sulfate salt. Preferably, the metal sulfate salt is one that readily separates into sulfate ions and metal ions in the treatment solution, and is easily introduced into the polyvinyl alcohol-based film in an ionic state. Examples of metals that form metal sulfate salts include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; and transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, and iron.

[0111] In the manufacture of polarizers, the zinc impregnation treatment and sulfate ion treatment described above may be performed at any stage. That is, the zinc impregnation treatment and sulfate ion treatment may be performed before the dyeing process or after the dyeing process. The zinc impregnation treatment and sulfate ion treatment may be performed simultaneously. In the present invention, it is preferable to use zinc sulfate as the zinc salt and the metal sulfate salt, and to perform the zinc impregnation treatment and sulfate ion treatment simultaneously by immersing the polyvinyl alcohol-based film in a treatment bath containing zinc sulfate. Alternatively, the zinc salt and the metal sulfate salt may be present in the dyeing solution, and the zinc impregnation treatment and / or sulfate ion treatment may be performed simultaneously with the dyeing process. The zinc impregnation treatment and sulfate ion treatment may be performed simultaneously with stretching.

[0112] In zinc impregnation and sulfate ion treatment, the zinc and sulfate ion content in the polarizer is adjusted by adjusting conditions such as the concentration of the zinc salt solution and metal sulfate solution, the immersion temperature of the polyvinyl alcohol-based film in the treatment bath, and the immersion time. In zinc impregnation and sulfate ion treatment, the temperature of the zinc salt solution and metal sulfate solution is usually around 15 to 85°C, preferably 25 to 70°C. The immersion time is usually in the range of 1 to 120 seconds, preferably 3 to 90 seconds. The concentration of the zinc salt solution and metal sulfate solution varies depending on the type of zinc salt and metal sulfate, but is usually around 0.5 to 20% by weight, preferably 1 to 10% by weight, more preferably 2 to 7% by weight. By setting the zinc salt concentration and metal sulfate concentration within these ranges, the zinc and sulfate ion content in the polarizer can be kept within the preferred ranges.

[0113] The polyvinyl alcohol-based film (stretched film) that has undergone the above treatments is subjected to a water washing process and a drying process according to conventional methods.

[0114] The washing process is usually carried out by immersing the polyvinyl alcohol-based film in a washing bath. The washing bath may be pure water or an aqueous solution of iodide (e.g., potassium iodide, sodium iodide, etc.). The concentration of the iodide aqueous solution is preferably 0.1 to 10% by weight. Additives such as zinc sulfate and zinc chloride may be added to the iodide aqueous solution.

[0115] The water washing temperature is typically in the range of 5 to 50°C, preferably 10 to 45°C, and more preferably 15 to 40°C. The immersion time is typically about 10 to 300 seconds, preferably 20 to 240 seconds. The water washing process may be performed only once, or multiple times as needed. If the water washing process is performed multiple times, the type and concentration of additives contained in the water washing bath used for each treatment are adjusted as appropriate.

[0116] The drying process for the polyvinyl alcohol-based film is carried out by any suitable method (e.g., natural drying, forced-air drying, heat drying). The thickness of the polarizer after the drying process is preferably 3 to 20 μm.

[0117] In the present invention, the surface of the obtained polarizer may be modified. Examples of surface modification treatments include corona treatment, plasma treatment, and itro treatment, with corona treatment being particularly preferred. By performing corona treatment, reactive functional groups such as carbonyl groups and amino groups are generated on the polarizer surface, improving adhesion with the durability-enhancing layer. In addition, surface foreign matter is removed by the ashing effect, and surface irregularities are reduced, making it possible to create a laminated optical film with excellent appearance characteristics.

[0118] The laminated optical film according to the present invention may also include a transparent protective film as another optical film. As the material constituting the transparent protective film, for example, a thermoplastic resin with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be 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 suitable additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the 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 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.

[0119] Furthermore, the material used to form the transparent protective film is preferably one that is excellent in terms of transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy, and is particularly good if it has a moisture permeability of 150 g / m². 2 It is more preferable that the amount is 24 hours or less, and 140 g / m² 2 Products with a shelf life of 24 hours or less are particularly preferred, and the density is 120 g / m². 2 Even better are those with a shelf life of 24 hours or less.

[0120] 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.

[0121] 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.

[0122] 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 acrylic film and a first optical film are laminated with an adhesive layer in between, The adhesive layer is formed of a cured layer of an adhesive composition containing at least a polymerizable compound. A coating step of applying the adhesive composition to at least one of the acrylic film and the first optical film, A method for manufacturing a laminated optical film, comprising: a bonding step of bonding the acrylic film and the first optical film so that the acrylic film and the adhesive layer are in direct contact; and an adhesion step of bonding the acrylic film and the first optical film via an adhesive layer formed by curing at least the adhesive composition by irradiating with active energy rays from the acrylic film side or the first optical film side. Each step will be described below.

[0123] (Coating process) The method for coating the adhesive composition onto at least one of the acrylic film and the first optical film is appropriately selected depending on the viscosity of the composition and the desired thickness. Examples include reverse coaters, gravure coaters (direct, reverse, and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, and rod coaters. The viscosity of the easy-to-bond composition and the adhesive composition is preferably 0.1 to 200 mPa·s, more preferably 1 to 100 mPa·s, and most preferably 5 to 50 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.

[0124] (Lamination process) The acrylic film and the first optical film are bonded together so that the acrylic film and the adhesive layer are in direct contact. When the adhesive composition is applied to the acrylic film during the coating process, the adhesive composition is applied directly to the acrylic film without applying an easy-to-use adhesive containing water-based urethane resin or the like to the acrylic film, and then bonded to the first optical film. Similarly, when the adhesive composition is applied to the first optical film during the coating process, the adhesive composition-coated surface of the first optical film and the acrylic film are bonded directly without the use of an intermediary adhesive or the like. When bonding the acrylic film and the first optical film via the adhesive composition, a roll laminator or the like is used for bonding.

[0125] (Adhesion process) The acrylic film and the first optical film are bonded together via an adhesive layer formed by irradiating the acrylic film surface or the first optical film surface with active energy rays 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.

[0126] 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 5kV to 300kV, and more preferably 10kV to 250kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive, resulting in insufficient curing. If the acceleration voltage exceeds 300kV, the penetrating force through the sample may be too strong, potentially damaging the first and second optical films. The irradiation dose is 5 to 100kGy, more preferably 10 to 75kGy. If the irradiation dose is less than 5kGy, the adhesive will not cure sufficiently. If it exceeds 100kGy, the first and second optical films will be damaged, resulting in a decrease in mechanical strength and yellowing, making it impossible to obtain the desired optical properties.

[0127] Electron beam irradiation is usually performed in an inert gas environment, but if necessary, it can also be performed in air or under conditions with a small amount of oxygen introduced. Depending on the materials of the first and second optical films, by appropriately introducing oxygen, oxygen inhibition can be intentionally caused on the first and second optical film surfaces that are initially hit by the electron beam, thereby preventing damage to the first and second optical films and allowing the electron beam to be efficiently directed only at the adhesive.

[0128] When manufacturing the laminated optical film according to the present invention, it is preferable to use an active energy ray that includes visible light in the wavelength range of 380 nm to 450 nm, and more preferably an active energy ray that has the highest irradiation amount of visible light in the wavelength range of 380 nm to 450 nm. When ultraviolet light and visible light are used, and a second optical film with ultraviolet absorption capability, such as an ultraviolet-opaque transparent protective film, is used, light with wavelengths shorter than approximately 380 nm is absorbed, so light with wavelengths shorter than 380 nm does not reach the adhesive composition and does not contribute to its polymerization reaction. Furthermore, light with wavelengths shorter than 380 nm absorbed by the first optical film and the second optical film is converted into heat, causing the first optical film and the second optical film themselves to generate heat, which can cause defects such as curling and wrinkling of the laminated optical film. Therefore, when ultraviolet and visible light are used in the present invention, it is preferable to use a device that does not emit light with a wavelength shorter than 380 nm as the active energy ray generator. More specifically, it is preferable that the ratio of the integrated illuminance in the wavelength range of 380 to 440 nm to the integrated illuminance in the wavelength range of 250 to 370 nm is 100:0 to 100:50, and more preferably 100:0 to 100:40. When manufacturing the laminated optical film according to the present invention, gallium-filled metal halide lamps and LED light sources that emit light in the wavelength range of 380 to 440 nm are preferred as active energy rays. Alternatively, light sources containing ultraviolet and visible light such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, incandescent bulbs, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, excimer lasers, or sunlight can be used, and ultraviolet light with a wavelength shorter than 380 nm can also be blocked using a bandpass filter. To improve the adhesion performance of the adhesive layer between the first optical film and the second optical film while preventing curling of the laminated optical film, it is preferable to use an active energy ray obtained by using a gallium-filled metal halide lamp and passing it through a bandpass filter capable of blocking light with wavelengths shorter than 380 nm, or to use an active energy ray with a wavelength of 405 nm obtained using an LED light source.

[0129] When manufacturing the laminated optical film according to the present invention in a continuous line, the line speed depends on the curing time of the adhesive composition, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and even more preferably 10 to 100 m / min. If the line speed is too low, productivity will be poor, or the damage to the first or second optical 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.

[0130] (Laminated optical film) The laminated optical film according to the present invention can be preferably used for forming various image display devices such as liquid crystal displays. The formation of liquid crystal displays can be carried out in accordance with conventional methods. That is, liquid crystal displays are generally formed by assembling components such as liquid crystal cells, polarizing films or optical films, and, if necessary, lighting systems, and incorporating drive circuits. However, 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, such as TN type, STN type, or π type.

[0131] Appropriate liquid crystal display devices can be formed, such as liquid crystal display devices in which optical laminates are arranged on one or both sides of a liquid crystal cell, or in which a backlight or reflector is used in the illumination system. In this case, the optical laminate according to the present invention can be installed on one or both sides of the liquid crystal cell. When optical laminates are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, appropriate components such as diffusers, anti-glare layers, anti-reflective films, protective plates, prism arrays, lens array sheets, light diffusers, and backlights can be arranged in appropriate positions in one or more layers. [Examples]

[0132] The following describes some embodiments of the present invention, but the embodiments of the present invention are not limited to these.

[0133] (Method for measuring the storage modulus of adhesive layers) The storage modulus of the adhesive layer was measured using the Dva225 dynamic viscoelasticity measuring device manufactured by IT Measurement Control Co., Ltd. under the following measurement conditions. Sample size: 50mm wide, 30mm long. Clamping distance 20mm, Measurement mode: pull, frequency: 1Hz, Heating rate: 5°C / min Dynamic viscoelasticity was measured, and the storage modulus at 25°C was used as the measured value.

[0134] <Method for estimating HSP of adhesive compositions> The HSP of the adhesive composition was determined by calculating the Hansen solubility parameter (HSP) for each constituent material of the composition using the Y-MB method of the Hansen Solubility Parameter in Practice (HSPiP), and then taking the average value according to the volume ratio in the composition.

[0135] <Method for measuring HSP in acrylic film> Acrylic film was immersed for 24 minutes in five solvents with different solubility: methyl ethyl ketone, methanol, n-hexane, trichlorobenzene, γ-butyrolactone, and a mixture thereof. The state of the transparent protective film after 24 hours of immersion was classified into three stages: (1) dissolved, (2) swollen, and (3) insoluble. Based on the solubility information obtained for each solvent, Hansen's solubility parameter (HSP) was calculated using Hansen Solubility Parameter in Practice (HSPiP) ver. 5.4.04 (http: / / www.hansen-solubility.com / index.php).

[0136] <HSP distance between the HSP of the transparent protective film and the HSP of the adhesive composition> When the dispersion term of the Hansen solubility parameter for acrylic film is σd, the polarity term is σp, and the hydrogen bonding term is σh, and the dispersion term of the Hansen solubility parameter for adhesive composition is σAd, the polarity term is σAp, and the hydrogen bonding term is σAh, the following formula is used: Ra = [4 × (σd - σAd)] 2 +2×(σp-σAp) 2 +2×(σh-σAh) 2 ] 1 / 2 This was defined as "the HSP distance between the HSP of the acrylic film and the HSP of the adhesive composition." The calculation was performed using the Hansen solubility parameters of the acrylic film and adhesive composition calculated using the method described above.

[0137] <Acrylic film> For the acrylic film, we used "RX420," a product manufactured by Nippon Shokubai Co., Ltd.

[0138] <LCD film> Based on the following photopolymerizable liquid crystal composition, the following λ / 2 phase difference film was obtained as a liquid crystal film.

[0139] <Photopolymerizable liquid crystal composition> A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242") was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (Bic Chemie's "BYK-360") and a photopolymerization initiator (IGM Resins' "Omnirad907") were added to this solution to prepare a liquid crystal composition solution. The amounts of the leveling agent and polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound.

[0140] <λ / 2 phase difference film> Using a biaxially oriented norbornene-based film (Zeonor Film, manufactured by Zeon Corporation, thickness: 33 μm, frontal retardation: 135 nm) as a substrate, the above liquid crystal composition was coated onto the substrate by a bar coater so that the phase difference was λ / 2, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the film was subjected to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2 A laminate was obtained in which a homogeneous oriented liquid crystal layer was provided by photocuring using ultraviolet light.

[0141] <Fabrication of polarizing films> 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 immersed in a 30°C swelling bath (water bath) for 30 seconds between rolls with different peripheral speed ratios to swell and stretched to 2.2 times its original size in the conveying direction (swelling process). Subsequently, it was immersed in a 30°C dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) for 30 seconds, adjusting the iodine concentration so that the polarizing film had a predetermined transmittance, and dyed while being stretched to 3.3 times its original size in the conveying direction, using the original polyvinyl alcohol film (a polyvinyl alcohol film that had not been stretched at all in the conveying direction) as a reference (dyeing process). Next, the dyed polyvinyl alcohol film was immersed for 28 seconds in a 40°C crosslinking bath (an aqueous solution with boric acid concentration of 3.5 wt%, potassium iodide concentration of 3.0 wt%, and zinc sulfate concentration of 3.6 wt%) to stretch it to 3.6 times its original size in the transport direction (crosslinking step). Furthermore, the resulting polyvinyl alcohol film was immersed for 60 seconds in a 64°C stretching bath (an aqueous solution with boric acid concentration of 4.8 wt%, potassium iodide concentration of 5.0 wt%, and zinc sulfate concentration of 5.0 wt%) to stretch it to 6.0 times its original size in the transport direction (stretching step), and then immersed for 10 seconds in a 29°C washing bath (potassium iodide concentration of 2.3 wt%) (washing step). The washed polyvinyl alcohol film was dried at 40°C for 30 seconds to produce a polarizing film. The thickness of the polarizing film was 18 μm.

[0142] <Preparation of polarizing film> As an adhesive, an aqueous solution containing polyvinyl alcohol resin containing acetoacetyl groups (average degree of polymerization 1,200, degree of saponification 98.5 mol%, degree of acetoacetylation 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, a 39 μm thick triacetylcellulose film (manufactured by Konica Minolta, trade name "KC4UY") with a hard coat layer was laminated to one side of the polarizing film obtained above via a water-based adhesive layer 7 as a transparent protective film, and a 30 μm thick acrylic film (RX420) was laminated to the other side via a water-based adhesive layer 3 using a roll laminating machine, and then heated and dried in an oven (temperature 60°C, time 4 minutes) to produce polarizing film 1.

[0143] <Activated energy rays> The active energy source is visible light (gallium-filled metal halide lamp). Irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc. Bulb: V-bulb Peak illuminance: 1600 mW / cm 2 Total irradiation dose: 1000 mJ / cm² 2 (Wavelengths of 380-440 nm were used.) Illuminance of visible light was measured using a Solatell Sola-Check system.

[0144] Examples 1-4 and Comparative Examples 1-2 On polarizing film 1, an adhesive composition adjusted to the proportions listed in Table 1 was applied to the acrylic film surface of the polarizing film and the homogeneous oriented liquid crystal layer surface of the liquid crystal film (a laminate of a biaxially oriented norbornene-based film and a homogeneously oriented liquid crystal layer) using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, rotation speed 140% / line speed). The adhesive layer was applied to these surfaces so that the thickness of the adhesive layer was 2 μm, and the two films were bonded together using a roll machine. Subsequently, the adhesive composition was cured by irradiating it with visible light from the biaxially oriented norbornene-based film side using an active energy ray irradiation device, and the biaxially oriented norbornene-based film was peeled off to obtain a laminated optical film.

[0145] The materials that make up the adhesive composition are as follows: • Polymerizable compound A: Acryloylmorpholine (trade name "ACMO", manufactured by KJ Chemicals) (HSP distance from acrylic film: 1.9) • Polymerizable compound B: Tripropylene glycol diacrylate (product name "Aronics M-220", manufactured by Toagosei Co., Ltd.) (HSP distance with acrylic film: 8.9) • Polymerizable compound C: Phenoxydiethylene glycol acrylate (product name "Light Acrylate P2H-A", manufactured by Kyoeisha Chemical Co., Ltd.) (HSP distance from acrylic film: 6.5) • Polymerizable compound D: 3-methacrylamide phenylboronic acid (product name "MAPBA", manufactured by Junsei Chemical Co., Ltd.) (HSP distance from acrylic film: 15.7) • Polymerizable compound E: 4-hydroxybutyl acrylate (trade name "4HBA", manufactured by Mitsubishi Chemical Corporation) (HSP distance with acrylic film: 6.4) • Polymerizable compound F: 1,9-nonanediol diacrylate (product name "Light Acrylate 1,9ND-A", manufactured by Kyoeisha Chemical Co., Ltd.) (HSP distance with acrylic film: 8.5) • Initiator 1 (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one): (Product name: Omnirad907, Manufacturer: IGM Resins BV) • Initiator 2 (Diethylthioxanthone): (Trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.)

[0146] Examples 5-6 The laminated optical films were manufactured in the same manner as in Examples 1-4 and Comparative Examples 1-2, except that an acrylic film was used as the first optical film instead of a liquid crystal film (i.e., an acrylic film-acrylic film laminated structure was adopted), and the composition of the adhesive was changed to that shown in Table 1.

[0147] (Appearance evaluation (evaluation of the presence or absence of oxalate spots)) A sample for humidification durability testing was prepared by laminating a manufactured laminated optical film to one side of a 0.7 mm thick alkali-free glass plate via an adhesive layer (20 μm thick). A humidification durability test was conducted by placing the sample in an environment of 85°C and 85% humidity and exposing it for 500 hours. Using a differential interference microscope, the transmission axes of the crossed nicol polarizer and the laminated optical film were set perpendicular to each other at a magnification of 5x, exposure time of 760 μs, and gain of 1x. The sample was then trimmed from within 5 mm of the sample edge to a 2 mm × 3 mm area with the highest number of oxalic acid spots, and the number of spots was counted using ImageJ ver. 1.8.0. A score of "○" was used if there were fewer than 15 spots, "△" if there were 15 to 30 spots, and "×" if there were more than 30 spots. The results are shown in Table 1.

[0148] (Initial peel strength (initial adhesive strength)) The obtained laminated optical film was cut to a size of 200 mm x 15 mm, and the laminated optical film was bonded to a glass plate. Then, an incision was made between the acrylic film and the first optical film with a utility knife, and the acrylic film and the first optical film were peeled off at a 90-degree angle at a peeling speed of 10,000 mm / min using a Tensilon, and the peel strength (N / 15 mm) was measured. If the acrylic film or the first optical film broke, or if the peel strength exceeded 1.5 N, it was marked as "◎", if the peel strength was between 1 and 1.5 N, it was marked as "〇", if the peel strength was 0.5 N or more but less than 1 N, it was marked as "△", and if the peel strength was less than 0.5 N, it was marked as "×". The results are shown in Table 1.

[0149] (Humidified peeling power (humidified adhesive power)) The obtained laminated optical film was left in an oven at 20°C and 98% humidity for 240 hours. After that, the laminated optical film was cut to a size of 200 mm x 15 mm and bonded to a glass plate. Then, an incision was made between the acrylic film and the first optical film with a utility knife, and the acrylic film and the first optical film were peeled off at a 90-degree angle at a peeling speed of 10,000 mm / min using a Tensilon, and the peel strength (N / 15 mm) was measured. If the acrylic film or the first optical film broke, or if the peel strength exceeded 1.5 N, it was marked as "◎", if the peel strength was between 1 and 1.5 N, it was marked as "〇", if the peel strength was 0.5 N or more but less than 1 N, it was marked as "△", and if the peel strength was less than 0.5 N, it was marked as "×". The results are shown in Table 1.

[0150] [Table 1]

[0151] The results in Table 1 show that the laminated optical films according to Examples 1 to 6 suppress the generation of bright spots originating from foreign matter even after the humidification durability test, exhibiting excellent appearance characteristics and superior adhesive strength between the laminated optical films.

Claims

1. A laminated optical film in which at least an acrylic film and a first optical film are laminated with an adhesive layer in between, The adhesive layer is formed of a cured layer of an adhesive composition containing at least a polymerizable compound. The acrylic film and the adhesive layer have a structure in which they are in direct contact. The HSP distance between the acrylic film and the adhesive layer is 1.9 or more and 5.0 or less. The elastic modulus of the adhesive layer is 10 8 Pa or greater and 3 × 10 9 It is less than or equal to Pa, The adhesive composition contains polymerizable compound D, The polymerizable compound D is given by the following general formula (1): 【Chemistry 1】 The compound represented by (wherein 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, and R1 and R2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group, or a heterocyclic group), A laminated optical film characterized in that, when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound D is 1 part by mass or more and 10 parts by mass or less.

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

3. The laminated optical film according to claim 1, wherein the thickness of the adhesive layer is 0.1 to 10 μm.

4. The laminated optical film according to claim 1, wherein a second optical film is further laminated on the surface of the first optical film opposite to the surface on which the acrylic film is laminated, via an adhesive layer.

5. The laminated optical film according to claim 4, wherein the second optical film is a liquid crystal film or a phase difference film.

6. The adhesive composition contains polymerizable compound A, The polymerizable compound A has an HSP distance of 0.0 or more and 4.0 or less from the acrylic film. The laminated optical film according to claim 1, wherein when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound A is 20 parts by mass or more and 60 parts by mass or less.

7. The adhesive composition contains polymerizable compound B, The polymerizable compound B is a compound having at least two polymerizable groups, The laminated optical film according to claim 1, wherein when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound B is 20 parts by mass or more and 50 parts by mass or less.

8. The adhesive composition contains polymerizable compound C, The polymerizable compound C has an HSP distance from the acrylic film that is greater than 4.0 and less than or equal to 8.

0. The laminated optical film according to claim 6, wherein when the total amount of polymerizable compounds contained in the adhesive composition is 100 parts by mass, the content of polymerizable compound C is less than or equal to the amount of polymerizable compound A.

9. The adhesive composition contains polymerizable compound E, The polymerizable compound E is a polymerizable compound containing a hydroxyl group, The laminated optical film according to claim 1, wherein, when the content of polymerizable compound D is 1, the content of polymerizable compound E is 1 or more and 15 or less.

10. An image display device comprising at least one laminated optical film as described in claim 1.

Images