Decomposed optical thin films

Abstract

The present invention relates to providing a laminated optical film suitable for suppressing end adhesion of a laminated optical film including an adhesive layer. The solution is as follows: The laminated optical thin film X of the present invention sequentially comprises an optical thin film 10, an adhesive layer 30, and an optical thin film 20 in the thickness direction H. The adhesive layer 30 is bonded to the optical thin film 10 and to the optical thin film 20. The adhesive layer 30 has a side surface 31, which is recessed further inward than the end edge 11 of the optical thin film 10 and the end edge 21 of the optical thin film 20 in a plane direction orthogonal to the thickness direction H.

Description

Technical Field

[0001] This invention relates to a multilayer optical thin film. Prior Technology

[0002] The display panel has a multilayer structure, including, for example, a pixel panel, a touch panel, and a surface protective cover. The multilayer structure of the display panel also includes various functional optical films having predetermined optical functions. Examples of functional optical films include polarizing films and retardation films. The functional optical films are, for example, assembled into the multilayer structure in a state where they are bonded to other optical films such as protective films through an adhesive, i.e., in the form of multilayer optical films. Such multilayer optical films are described, for example, in Patent Document 1 below. Previous technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-147865 Summary of the Invention

[0004] The problem the invention aims to solve Long, multilayer optical films are manufactured in a roll-to-roll manner and processed in roll form. On the other hand, as display panels become thinner, the thinning of optical films continues. The thinner the optical films in a multilayer optical film, the easier it is for adjacent multilayer optical films to adhere to each other at the ends of the roll (multilayer optical film roll material) (end-bonding). Specifically, as follows.

[0005] In the case of laminated optical film rolls, a load is applied in the thickness direction (diameter direction of the roll). Under heavy loads, a portion of the adhesive layer (adhesive) seeps out from between the optical films at the ends of the laminated optical films. When this adhesive extends beyond the aforementioned optical films at the ends of the roll and reaches adjacent optical films, these adjacent optical films adhere to each other through the adhesive. The thinner the optical films, the easier it is for the adhesive seeping out from between the optical films to reach adjacent optical films after extending beyond the optical film. Therefore, the thinner the optical films in a laminated optical film, the easier it is for end bonding to occur. In the case of laminated optical films used in reversibly bendable (foldable) display panels, the optical films and adhesive layers are soft, making the aforementioned end bonding particularly prone to occur. Furthermore, in the case of laminated optical films used in foldable display panels, the adhesive layer between the optical films is soft, making end bonding also prone to occur during the shaping process of the laminated optical films. Furthermore, when the stacked optical film with easy end bonding is mounted on flexible devices such as smartphones, stress on the stacked optical film will be generated in the shear direction of the bonding interface when used for a long time in a high-temperature environment, making it easy for the bonding interface to peel off.

[0006] The present invention provides a laminated optical film suitable for suppressing end adhesion of a laminated optical film including an adhesive layer.

[0007] The means to solve the problem The present invention [1] is a laminated optical thin film, which has a first optical thin film, an adhesive layer and a second optical thin film sequentially in the thickness direction; the adhesive layer is bonded to the first optical thin film and to the second optical thin film; the adhesive layer has a side surface, which is recessed further inward than the first edge of the first optical thin film and the second edge of the second optical thin film in a plane direction orthogonal to the thickness direction.

[0008] In this laminated optical film, as described above, the adhesive layer sandwiched between the first and second optical films has a side surface that is recessed further inward than the first end edge of the first optical film and the second end edge of the second optical film. At the end edge of the laminated optical film, where the adhesive layer has the recessed side surface described above, even when a load is applied to the laminated optical film in the thickness direction, the adhesive layer can still be prevented from seeping out between the optical films. Therefore, this laminated optical film is suitable for suppressing end adhesion.

[0009] The present invention [2] includes a stacked optical thin film as described in [1] above, wherein the recess length of the side surface is 0.05µm or more, measured from the end edge located inside the surface direction of the first end edge and the second end edge described above.

[0010] The configuration is suitable for suppressing the seepage of the adhesive layer from between the optical films, and therefore suitable for suppressing end adhesion. Suppression of end adhesion helps ensure the transportability and handleability of the laminated optical films during processing.

[0011] The present invention [3] includes a stacked optical film as described in [1] or [2] above, wherein the recess length of the side surface is less than 1.0µm, measured from the end edge located inside the surface direction of the first end edge and the second end edge described above.

[0012] The configuration is suitable for suppressing peeling between the first and second optical films at the ends of the laminated optical films. For example, this configuration can ensure the adhesion between the optical films using the adhesive layer even in high temperature and high humidity environments, thus effectively suppressing peeling. Furthermore, the above configuration can also ensure the reinforcing function of the adhesive layer at both ends (first end and second end) of the first and second optical films, thus effectively ensuring the impact resistance of both ends. Simple Explanation of the Diagram

[0013] Figure 1 is a cross-sectional schematic diagram of one embodiment of the stacked optical thin film of the present invention. Figure 2 is a partially enlarged cross-sectional view of the end of the laminated optical thin film shown in Figure 1. Figure 3 is an enlarged cross-sectional view of the end of a modified example of the laminated optical thin film shown in Figure 1. In this modified example, the side of the adhesive layer has a curved, recessed shape. Figure 4 is an enlarged cross-sectional view of the end of another variation of the laminated optical thin film shown in Figure 1. In this variation, the side of the adhesive layer has a partially recessed shape. Implementation

[0014] As one embodiment of the laminated optical film of the present invention, the laminated optical film X, as shown in FIG1, comprises an optical film 10 (first optical film), an optical film 20 (second optical film), and an adhesive layer 30. The laminated optical film X has a sheet shape of a predetermined thickness and extends in a direction orthogonal to the thickness direction H (planar direction). Specifically, the laminated optical film X comprises the optical film 10, the adhesive layer 30, and the optical film 20 sequentially in the thickness direction H. The adhesive layer 30 is used to bond the optical films 10 and 20. The laminated optical film has an elongated strip shape extending in one direction and is processed in the form of a roll. Furthermore, the laminated optical film X is a composite film incorporated into the laminated structure of a display panel.

[0015] In this embodiment, the optical thin film 10 is a functional optical thin film. Examples of functional optical thin films include polarizing films and phase difference films.

[0016] Examples of polarizing films include hydrophilic polymer films that have undergone dyeing with dichroic substances and subsequent stretching treatment. Examples of dichroic substances include iodine and dichroic dyes. Examples of hydrophilic polymer films include polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified films of ethylene-vinyl acetate copolymers. Another example of a polarizing film is a polyene-oriented film. Examples of materials for polyene-oriented films include dehydrated PVA and dehydrochlorinated polyvinyl chloride. Considering the excellent optical properties such as polarization characteristics, a PVA film that has undergone dyeing with iodine and subsequent uniaxial stretching treatment is preferable for polarizing films.

[0017] From the perspective of thinning, the thickness of the optical thin film 10, which serves as a polarizing element thin film, should preferably be 15µm or less, more preferably 12µm or less, even more preferably 10µm or less, and especially preferably 8µm or less. Thin polarizing thin films have excellent visibility due to their smaller thickness variations, and their dimensional changes due to temperature variations are small, resulting in excellent thermal shock resistance. From the perspective of strength, the thickness of the optical thin film 10, which serves as a polarizing element thin film, should preferably be 3µm or more, and more preferably 5µm or more.

[0018] Examples of phase retardation films include, for example, λ / 2 wavelength films, λ / 4 wavelength films, and viewing angle compensation films. Materials for phase retardation films include, for example, polymer films that have undergone birefringence through a stretching process. Examples of polymer films include cellulose films and polyester films. Examples of cellulose films include, for example, cellulose triacetate films. Examples of polyester films include, for example, polyethylene terephthalate films and polyethylene naphthalate films. The thickness of the optical film 10, as a phase retardation film, is, for example, 20 µm or more, and for example, 150 µm or less. Furthermore, phase retardation films can also be suitable films comprising a substrate such as a cellulose film and an alignment layer of a liquid crystal compound such as a liquid crystal polymer on that substrate.

[0019] In this embodiment, the optical film 20 is a transparent protective film. The transparent protective film is, for example, a flexible transparent resin film. Examples of materials for the transparent protective film include polyolefins, polyesters, polyamides, polyimides, polyvinyl chloride, polyvinyl chloride, cellulose, modified cellulose, polystyrene, and polycarbonate. Examples of polyolefins include cyclic olefin polymers (COP), polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers. Examples of polyesters include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Examples of polyamides include polyamide 6, polyamide 6,6, and some aromatic polyamides. Examples of modified cellulose include cellulose triacetate. These materials can be used alone or in combination of two or more. From a cleanliness perspective, polyolefins are preferable for the transparent protective film, and COPs are more suitable. Furthermore, the optical thin film 20 is preferably a uniaxially stretched thin film or a biaxially stretched thin film.

[0020] From the perspective of the strength of the multilayer optical film X, the thickness of the optical film 20 should preferably be 5µm or more, preferably 10µm or more, and even more preferably 20µm or more. From the perspective of the thinning of the multilayer optical film X, the thickness of the optical film 20 should preferably be 100µm or less, preferably 70µm or less, and even more preferably 50µm or less.

[0021] Adhesive layer 30 is a cured form of the adhesive composition. Adhesive layer 30 is directly bonded to optical film 10 and optical film 20. The adhesive composition contains a curable resin. The specific composition of the adhesive composition is described below.

[0022] From the perspective of the bonding strength between optical films 10 and 20, the thickness of adhesive layer 30 should preferably be 0.1µm or more, preferably 0.4µm or more, more preferably 0.7µm or more, and especially preferably 0.8µm or more. From the perspective of thinning the laminated optical film X, the thickness of adhesive layer 30 should preferably be 5µm or less, preferably 3µm or less, more preferably 1.5µm or less, and especially preferably 1µm or less.

[0023] In the laminated optical film X, the adhesive layer 30 sandwiched between the optical films 10 and 20 has a side surface 31 that is recessed further inward than the end edges 11 and 21 of the optical films 10 and 20 (the figure schematically shows the end edges 11 and 21 being located at the same position in the planar direction). At the end edge of the laminated optical film X, where the adhesive layer 30 has the recessed side surface 31, even when a load is applied to the laminated optical film X in the thickness direction H, the adhesive layer 30 can still be prevented from seeping out between the optical films 10 and 20. Therefore, the laminated optical film X is suitable for suppressing the aforementioned end adhesion. Suppression of end adhesion helps ensure the transportability and handleability of the laminated optical film during processing.

[0024] Measured from the innermost edge of the end edge 11 or 21 in the planar direction, the recessed length L1 of the side surface 31 should preferably be 0.05µm or more, more preferably 0.1µm or more, and even more preferably 0.2µm or more. This configuration is suitable for suppressing the seepage of the adhesive layer 30 from between the optical films 10 and 20, thus effectively suppressing end adhesion. Specifically, the recessed length L1 is the planar distance between the innermost edge of the end edge 11 or 21 of the optical films 10 or 20 in the planar direction and the innermost end of the side surface 31 of the adhesive layer 30 in the planar direction.

[0025] The recessed length L1 is preferably 1.0µm or less, more preferably 0.8µm or less, and even more preferably 0.6µm or less. This configuration is suitable for suppressing peeling between optical films 10 and 20 at the ends of the laminated optical film X. For example, even in high temperature and high humidity environments, this configuration can ensure the adhesion between optical films 10 and 20 using the adhesive layer 30, thus effectively suppressing peeling (peeling caused by the large thermal shrinkage of the adhesive layer 30 during the processing of the laminated optical film). Furthermore, this configuration also ensures the reinforcing function of the adhesive layer 30 on the ends 10a and 20a of the optical films 10 and 20, thus effectively ensuring the impact resistance of the ends 10a and 20a.

[0026] In the thickness direction section shown in Figure 2, the aforementioned side surface 31 has a generally straight shape at the position receding in the surface direction from the end edges 11, 21. However, the adhesive layer 30 can also have a curved and concave side surface 31A as shown in Figure 3 (the figure schematically shows the case where the ends 31a, 31a of the side surface 31A in the thickness direction H are located at the same position as the end edges 11, 21 in the surface direction). In the thickness direction section shown in Figure 3, the side surface 31A has a curved, generally V-shaped shape, specifically a shape that gradually concaves inward in the surface direction from both ends (ends 31a, 31a) in the thickness direction H toward the middle part (deepest part 31b). The concavity length L1 of the side surface 31A is the surface direction distance between the end edges 11, 21 of the optical thin films 10, 20 located in the surface direction and the innermost end (deepest part) 31b of the side surface 31A in the surface direction. The case where the adhesive layer 30 has side 31A is the same as the case where the adhesive layer 30 has side 31, and will achieve the above-mentioned technical effects (suppress end adhesion, ensure peeling between optical film ends, and ensure the impact resistance of optical film ends).

[0027] The adhesive layer 30 can also have a partially recessed side surface 31B as shown in FIG. 4 (the figure schematically shows the outermost end 31a of side surface 31B and the end edges 11, 21 being located at the same position in the surface direction). Furthermore, the side surface 31B shown in FIG. 4 has an end face F and an inclined surface D. The end face F in side surface 31B is located on the optical film 10 side and is flush with the end edge 11. The inclined surface D in side surface 31B is located on the optical film 20 side, and it is inclined inward from the end face F towards the optical film 20 in the surface direction (the more inward the inclined surface D is in the surface direction, the closer it is to the optical film 20). Side surface 31B can have a partially recessed shape or an inclined surface (not shown) on the optical film 10 side, or it can have a partially recessed shape in the middle of the thickness direction H (not shown), instead of the aforementioned partially recessed shape. The recessed length L1 of side 31B is the distance in the plane direction between the inner edge of the end edges 11 and 21 of the optical films 10 and 20 and the innermost end 31b of side 31B in the plane direction. The case where the adhesive layer 30 has side 31B is the same as the case where the adhesive layer 30 has side 31, and will achieve the above-mentioned technical effects (suppress end adhesion, ensure peeling between the ends of the optical films, and ensure the impact resistance of the ends of the optical films).

[0028] The first indentation modulus of the adhesive layer 30, measured by nanoindentation at 25°C, is preferably 0.01 GPa or higher, more preferably 0.03 GPa or higher, more preferably 0.05 GPa or higher, and especially preferably 0.07 GPa or higher (the first indentation modulus is set as the indentation modulus under the first measurement conditions; the first measurement conditions are as described later with reference to the embodiments, in which the maximum indentation depth of the indenter on the test sample during the application of load is 200 nm). This configuration is preferred from the viewpoint of ensuring the bonding force between the optical films 10 and 20. Furthermore, this configuration helps to ensure the aforementioned impact resistance of the optical films 10 and 20. Also, the first indentation modulus is preferably 5 GPa or lower, more preferably 3 GPa or lower, and more preferably 1 GPa or lower. This configuration is suitable for ensuring the flexibility of the adhesive layer 30 when the laminated optical film X is used in a repeatedly bendable (foldable) display panel. One method for adjusting the indentation elastic modulus of the adhesive layer 30 is, for example, adjusting the composition of the adhesive composition. Specifically, an effective method for adjusting the indentation elastic modulus of the adhesive layer 30 is to adjust the functional groups of the polymeric compound in the adhesive composition forming the adhesive layer 30, i.e., to adjust the acrylonitrile equivalent or epoxy equivalent of the polymeric compound.

[0029] Nanoindentation is a method for determining the properties of a sample at the nanoscale. In this embodiment, nanoindentation is performed according to ISO 14577. Nanoindentation involves pressing an indenter into the sample mounted on a platform (load application process) and then pulling the indenter out of the sample (unloading process), measuring the load acting between the indenter and the sample and the relative displacement of the indenter relative to the sample during this series of processes (load-displacement measurement). This yields a load-displacement curve. From this load-displacement curve, the properties of the sample can be determined based on nanoscale measurements. Load-displacement measurements of the adhesive layer cross-section using nanoindentation can be performed, for example, using a nanoindenter (trade name "Triboindenter," manufactured by Hysitron). Specifically, as described later with reference to the embodiments.

[0030] The second indentation modulus of the adhesive layer 30, measured by nanoindentation at 25°C, is preferably 0.5 GPa or higher, more preferably 1 GPa or higher, more preferably 1.5 GPa or higher, and especially preferably 2 GPa or higher (the second indentation modulus is set as the indentation modulus under the second measurement conditions; the second measurement conditions are as described later with reference to the embodiments, in which the maximum indentation depth of the indenter on the test sample during the application of load is 50 nm). This configuration is preferred from the viewpoint of ensuring the adhesion between the optical films 10 and 20. Furthermore, this configuration helps to ensure the aforementioned impact resistance of the optical films 10 and 20. Also, the second indentation modulus is preferably 7 GPa or lower, more preferably 5 GPa or lower, and more preferably 3 GPa or lower. This configuration is suitable for ensuring the flexibility of the adhesive layer 30 when the laminated optical film X is used in a repeatedly bendable (foldable) display panel.

[0031] In the laminated optical thin film X, the 90° peel strength of the optical thin film 20 against the optical thin film 10 at 25°C is preferably 1 N / 15 mm or more, more preferably 1.2 N / 15 mm or more, and even more preferably 1.5 N / 15 mm or more. This configuration is suitable for achieving good adhesion between the optical thin films 10 and 20, and is particularly suitable for ensuring adhesion between the optical thin films 10 and 20 used in foldable display panels. The 90° peel strength is, for example, 10 N / 15 mm or less. The 90° peel strength can be measured, for example, using a TENSILON universal testing machine (product name "RTC", manufactured by A&D Company, Limited). In this measurement, the measurement temperature is set to 25°C, the peel angle is set to 90°, and the peel speed is set to 1000 mm / min. Furthermore, the 90° peel strength can be adjusted, for example, by adjusting the composition of the adhesive. Specifically, methods for adjusting the 90° peel strength include, for example, adjusting the number of functional groups of the polymeric compound in the adhesive composition, i.e., adjusting the acrylonitrile equivalent or epoxy equivalent of the polymeric compound.

[0032] The ratio of the aforementioned 90° peel strength (N / 15mm) to the first indentation modulus (GPa) is preferably 5 or more, more preferably 10 or more, more preferably 15 or more, and preferably 30 or less, more preferably 25 or less. The ratio of the aforementioned 90° peel strength (N / 15mm) to the second indentation modulus (GPa) is preferably 0.2 or more, more preferably 0.3 or more, more preferably 0.4 or more, and preferably 5 or less, more preferably 3 or less, more preferably 2 or less. This configuration is particularly effective in suppressing peeling between the optical films 10 and 20 when the laminated optical film X is repeatedly bent.

[0033] The adhesive layer 30 is, for example, a cured product containing an adhesive composition (active energy line curing composition) of an active energy line curing resin. Examples of active energy line curing compositions include electron beam curing compositions, ultraviolet curing compositions, and visible light curing compositions. Furthermore, in this embodiment, the active energy line curing composition is either a free radical polymerization composition or a cationic polymerization composition, or both.

[0034] When a hardening composition of an active energy line is a free radical polymer type composition, the composition contains a free radical polymerizable compound as a monomer. A free radical polymerizable compound is a compound having a free radical polymerizable functional group. Examples of free radical polymerizable functional groups include those containing vinyl unsaturated bonds. Examples of groups containing vinyl unsaturated bonds include (meth)acryl, vinyl, and allyl. (Meth)acryl refers to acrylonitrile and / or methacryl. From the viewpoint of the hardening properties of the active energy line hardening composition, it is preferable that the active energy line hardening composition contains a free radical polymerizable compound having a (meth)acryl group as the main component. The main component refers to the component with the highest mass percentage. The proportion of the free radical polymerizable compound containing a (meth)acryl group in the active energy line hardening composition is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. Furthermore, examples of free radical polymers include monofunctional free radical polymers and polyfunctional free radical polymers with two or more functions.

[0035] Monofunctional free radical polymerizable compounds include, for example, (meth)acrylamide derivatives containing a (meth)acrylamide group. Examples of (meth)acrylamide derivatives include: (meth)acrylamide derivatives containing N-alkyl groups, (meth)acrylamide derivatives containing N-hydroxyalkyl groups, (meth)acrylamide derivatives containing N-aminealkyl groups, (meth)acrylamide derivatives containing N-alkoxy groups, and (meth)acrylamide derivatives containing N-mercaptoalkyl groups. Examples of (meth)acrylamide derivatives containing N-alkyl groups include: 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,N-diethylacrylamide is preferred. Examples of N-hydroxyalkyl (meth)acrylamide derivatives include: N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-hydroxymethyl-N-propane (meth)acrylamide. N-hydroxyethylacrylamide is preferred. (Methacrylamide)acrylamide derivatives may be used alone or in combination of two or more.

[0036] Examples of monofunctional free radical polymerizable compounds include (meth)acrylic acid derivatives having a (meth)acryloxy group. Examples of such (meth)acrylic acid derivatives include alkyl (meth)acrylates and other (meth)acrylic acid derivatives. (Methacryl)acrylic acid derivatives can be used alone or in combination of two or more.

[0037] Examples of alkyl methacrylates include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, 2,2-dimethylbutyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0038] Examples of (meth)acrylic acid derivatives other than alkyl (meth)acrylates include cycloalkyl (meth)acrylates, aralkyl (meth)acrylates, hydroxyl-containing (meth)acrylic acid derivatives, alkoxy-containing (meth)acrylic acid derivatives, and phenoxy-containing (meth)acrylic acid derivatives. Examples of cycloalkyl (meth)acrylates include cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate. Examples of aralkyl (meth)acrylates include benzyl (meth)acrylate and 3-phenoxybenzyl (meth)acrylate. Examples of hydroxyl-containing (meth)acrylic acid derivatives include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methacrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. Examples of alkoxy-containing (meth)acrylate derivatives include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate. Examples of phenoxy-containing (meth)acrylate derivatives include phenoxyethyl (meth)acrylate and phenoxydiethylene glycol (meth)acrylate. (Meth)acrylate derivatives other than alkyl (meth)acrylates may preferably be selected from at least one of the group consisting of 3-phenoxybenzyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and phenoxydiethylene glycol acrylate.

[0039] Monofunctional free radical polymerizable compounds can also include carboxyl-containing monomers. Examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0040] Monofunctional free radical polymerizable compounds also include lactone-based vinyl monomers. Examples of lactone-based vinyl monomers include N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactone, and methylvinylpyrrolidone.

[0041] Monofunctional free radical polymerizable compounds may also include vinyl monomers having nitrogen-containing heterocycles. Examples of such monomers include: vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidine, vinylpyridine, vinylpyrrole, vinylimidazolium, vinylpyrazole, and vinylmorpholin.

[0042] Polyfunctional radical polymerizable compounds may include, for example: 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, neopentyl glycol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, cyclic trimethylolpropane acetal (meth)acrylate, dialkyldiol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyltetrol tri(meth)acrylate, neopentyltetrol tetra(meth)acrylate, dinepentyltetrol penta(meth)acrylate, and dinepentyltetrol hexa(meth)acrylate. Tripropylene glycol diacrylate is also suitable. Polyfunctional radical polymerizable compounds may be used alone or in combination of two or more. Multifunctional free radical polymerizable compounds can function as crosslinking agents.

[0043] When the active energy line curing composition is an ultraviolet-curing composition or a visible light-curing composition, it should preferably contain a photopolymerization initiator. Examples of photopolymerization initiators include diphenyl ketone compounds, benzoin ether compounds, and 9-oxosulfuron. Compounds. Examples of diphenyl ketone compounds include benzyl, diphenyl ketone, benzoic acid, and 3,3'-dimethyl-4-methoxydiphenyl ketone. Examples of benzoin ether compounds include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether. 9-Oxysulfuron Examples of compounds include: 9-oxosulfur 2-Chloro-9-oxysulfur 2-Methyl-9-oxosulfur 2,4-Dimethyl-9-oxosulfur Isopropyl 9-Oxysulfur 2,4-Dichloro-9-oxosulfur 2,4-Diethyl-9-oxosulfur 2,4-Diisopropyl-9-oxosulfuron and dodecyl 9-oxosulfur .

[0044] When the active energy line-curing composition is a visible light-curing composition, a photopolymerization initiator with high sensitivity to light above 380nm should be used. Examples of photopolymerization initiators include: 2-methyl-1-(4-methylthiophenyl)-2-mofolinylprop-1-one, 2-benzyl-2-dimethylamino-1-(4-mofolinylphenyl)-but-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-mofolinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(n5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium.

[0045] The photopolymerization initiator should preferably be 2,4-diethyl-9-oxosulfuron. And / or 2-methyl-1-(4-methylthiophenyl)-2-methylfolinylprop-1-one.

[0046] Relative to 100 parts by mass of the curing component (free radical polymerizable compound), the content of the photopolymerization initiator in the active energy line curing composition should preferably be 0.1 parts by mass or more, more preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0047] When the active energy line curing composition is a cationic polymer composition, the composition contains a cationic polymeric compound as a monomer. The cationic polymeric compound is a compound having a cationic polymeric functional group, including monofunctional cationic polymeric compounds having one cationic polymeric functional group and polyfunctional cationic polymeric compounds having two or more cationic polymeric functional groups. Monofunctional cationic polymeric compounds have relatively low liquid viscosity. By incorporating the monofunctional cationic polymeric compound into the resin composition, the viscosity of the resin composition can be reduced. Furthermore, monofunctional cationic polymeric compounds mostly possess functional groups capable of exhibiting various functions. By incorporating the monofunctional cationic polymeric compound into the resin composition, the resin composition and / or the cured resin composition can exhibit various functions. On the other hand, by curing a resin composition incorporating a polyfunctional cationic polymeric compound, a cured product with a 3D cross-linked portion can be obtained (the polyfunctional cationic polymeric compound functions as a cross-linking agent). From this perspective, it is preferable to utilize polyfunctional cationic polymeric compounds. When using both monofunctional cationic polymeric compounds and polyfunctional cationic polymeric compounds, the amount of the polyfunctional cationic polymeric compound is, for example, 10 parts by mass or more, and for example, 1000 parts by mass or less, relative to 100 parts by mass of the monofunctional cationic polymeric compound. Examples of cationic polymeric functional groups include epoxy groups, oxetyl groups, and vinyl ether groups. Examples of compounds containing epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. From the viewpoint of the curability and adhesion of cationic polymeric compositions, alicyclic epoxy compounds are preferable to be used as epoxy groups. Examples of alicyclic epoxy compounds include: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, or caprolactone-modified, trimethylcaprolactone-modified, and valproicone-modified versions of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate. Commercially available alicyclic epoxy compounds include, for example, CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, and CELLOXIDE 2085 (all manufactured by DAICL Chemical Co., Ltd.), and Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, and R-6110 (all manufactured by DOW CHEMICAL Japan Co., Ltd.). From the perspective of improved curability and reduced viscosity of cationic polymeric compositions, compounds containing oxetane groups and / or compounds containing vinyl ether groups are preferable.Examples of compounds containing oxetane include: 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetane)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetane)methyl] ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenolic varnish oxetane. Commercially available examples of compounds containing oxetane include: ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, and ARON OXETANE OXT-212 (all manufactured by Toa Synthetic Co., Ltd.). Compounds containing a vinyl ether group include, for example: 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanediethanol divinyl ether, cyclohexanediethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and neopentyl tetravinyl ether.

[0048] When the active energy line curing composition is an ultraviolet-curing composition or a visible light-curing composition, it contains a photocationic polymerization initiator. When irradiated by active energy lines (visible light, ultraviolet light, X-rays, electron beams, etc.), the photocationic polymerization initiator generates cationic species or Lewis acids, initiating the polymerization reaction of cationic polymerizable functional groups. Examples of photocationic polymerization initiators include photoacid generators and photobase generators; photoacid generators are preferred. When the active energy line curing composition is a visible light-curing composition, it is particularly advisable to use a photocationic polymerization initiator with high sensitivity to light above 380 nm. Furthermore, when using a photocationic polymerization initiator, it is advisable to also use a photosensitizer that exhibits maximum absorption to light with wavelengths longer than 380 nm. Photocationic polymerization initiators are generally compounds that exhibit maximum absorption in the wavelength region around 300 nm or shorter. Therefore, by using them in conjunction with photosensitizers that exhibit maximum absorption in wavelengths longer than 380 nm, the generation of cationic species or Lewis acids from the photocationic polymerization initiator can be effectively promoted using light with wavelengths longer than 380 nm. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organosulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducing pigments. These can be used alone or in combination of two or more. Anthracene compounds are particularly ideal due to their excellent photosensitizing effect. Commercially available anthracene compounds as photosensitizers include ANTHRACURE UVS-1331 and ANTHRACURE UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.). The content of the photosensitizer in the composition is, for example, 0.1 to 5% by weight.

[0049] Active energy line curable compositions may also contain oligomers. Examples of oligomers include acrylic oligomers, fluoro oligomers, and polysiloxane oligomers; acrylic oligomers are preferred. The blending of oligomers into the active energy line curable composition helps suppress shrinkage during curing. Suppression of curing shrinkage in the active energy line curable composition appropriately reduces the interfacial stress between the formed adhesive layer 30 and the optical films 10 and 20. Suppression of interfacial stress helps ensure adhesion between the optical films 10 and 20.

[0050] Examples of (meth)acrylic acid monomers that form acrylic acid oligomers include: alkyl (meth)acrylic acid esters with 1 to 20 carbon atoms, cycloalkyl (meth)acrylic acid esters, aralkyl (meth)acrylic acid esters, polycyclic (meth)acrylic acid esters, hydroxyl-containing (meth)acrylic acid esters, and halogen-containing (meth)acrylic acid esters. Examples of alkyl methacrylates include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl methacrylate, isobutyl methacrylate, S-butyl methacrylate, tributyl methacrylate, n-pentyl methacrylate, tripentyl methacrylate, 3-pentyl methacrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl methacrylate, cetyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 4-methyl-2-propylpentyl (meth)acrylate, and N-octadecyl (meth)acrylate. Examples of cycloalkyl methacrylates include cyclohexyl methacrylate and cyclopentyl methacrylate. Examples of aralkyl methacrylates include benzyl methacrylate. Examples of polycyclic (meth)acrylates include 2-isocamphene (meth)acrylate, 2-norcamphenylmethyl (meth)acrylate, 5-norcamphen-2-yl-methyl (meth)acrylate, and 3-methyl-2-norcamphenylmethyl (meth)acrylate. Examples of hydroxyl-containing (meth)acrylates include hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate. Examples of halogen-containing (meth)acrylates include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, and heptadecafluorodecyl (meth)acrylate. These (meth)acrylates can be used alone or in combination of two or more.

[0051] The weight average molecular weight (Mw) of acrylic oligomers should preferably be below 15,000, more preferably below 10,000, and even more preferably below 5,000. The Mw of acrylic oligomers should preferably be above 500, more preferably above 1,000, and even more preferably above 1,500.

[0052] The content of acrylic oligomer in the active energy line hardening type composition should preferably be 2% by mass or more, more preferably 4% by mass or more, and preferably less than 20% by mass, more preferably less than 15% by mass.

[0053] The active energy line hardening composition may also contain other components. Other components may include silane coupling agents, leveling agents, surfactants, plasticizers, and ultraviolet absorbers. The amount of these other components should preferably be less than 10 parts by mass relative to 100 parts by mass of the hardening component, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass, and for example, more than 0.01 parts by mass.

[0054] From the perspective of coatability in the coating step described later, the viscosity of the active energy linear hardening composition at 25°C should preferably be 3 mPa·s or higher, more preferably 5 mPa·s or higher, more preferably 10 mPa·s or higher, and preferably 100 mPa·s or lower, more preferably 50 mPa·s or lower, and more preferably 30 mPa·s or lower. The viscosity of the composition is measured using an E-type viscometer (cone-plate viscometer).

[0055] The laminated optical thin film X can be manufactured, for example, in the following manner.

[0056] First, an active energy line-curing composition is coated onto one side (the pre-bonding surface) of one of the optical films (optical film 10 or optical film 20) to form a coating of the composition (coating step). Prior to this coating step, the pre-bonding surface of the optical film may also undergo surface modification treatment. Surface modification treatments may include corona treatment, plasma treatment, excimer laser treatment, and flame treatment. The coating method in this step may include, for example, a reverse coating machine, a gravure coating machine, a bar reverse coating machine, a roll coating machine, a die coating machine, a bar coating machine, and a rod coating machine.

[0057] Next, one optical film (optical film 20 or optical film 10) is laminated to one optical film over the composition coating. The lamination can be performed using, for example, a roll laminator.

[0058] Next, an active energy line is irradiated onto the composition coating between optical thin films 10 and 20, causing the coating (an active energy line-cured composition) to harden and form an adhesive layer 30 (the adhesive layer 30 is not a pressure-sensitive adhesive layer). In this way, optical thin films 10 and 20 are bonded together through the adhesive layer 30, thus obtaining the raw material film of the laminated optical thin film X. From the viewpoint of suppressing the degradation of the optical thin film 10 as a functional optical thin film, it is preferable to irradiate the active energy line from the optical thin film 30 side in this step. The active energy line can be an electron beam, ultraviolet light, or visible light. An electron beam irradiation mechanism can be, for example, an electron beam accelerator. Examples of ultraviolet and visible light sources include: LED lights, gallium-filled metal halide lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, and gallium lamps. In this step, a wavelength cutoff filter can also be used as needed to cut off a portion of the wavelength region of ultraviolet and / or visible light emitted from the light source.

[0059] Next, at least a portion of the periphery of the raw film is shaped (shape forming step). For example, one end of the long side of the rolled raw film is trimmed. For example, the rolled raw film is cut into single sheets. Such shape forming methods include, for example, laser processing using CO2 laser irradiation, cutting using a cutting tool, cutting using a punching tool, and end milling.

[0060] By irradiating with a CO2 laser, the adhesive layer 30 undergoes significant thermal shrinkage at the outer processing area of ​​the original film, resulting in a side surface 31 (or side surface 31A) that is recessed further inward than the end edges 11, 21 of the optical films 10, 20. Specifically, the end of the adhesive layer 30 shrinks so that the side surface 31 of the adhesive layer 30, either entirely or partially, recedes further inward than the end edges 11, 21 of the optical films 10, 20, thus forming a recessed side surface 31 (or side surface 31A). The length of the end shrinkage of the adhesive layer 30, i.e., the recessed length L1, can be adjusted, for example, by adjusting the composition of the adhesive layer 30 and the CO2 laser irradiation conditions.

[0061] By cutting with a cutting tool, the end of the adhesive layer 30 is partially removed, thereby forming a side surface 31 (or side surfaces 31A, 31B) that is recessed further inward than the end edges 11, 21 of the optical films 10, 20. Methods for adjusting the location and extent of partial removal include, for example, adjusting the difference in elastic modulus between the optical films 10, 20 and the adhesive layer 30, adjusting the thermal shrinkage rate and thickness of the adhesive layer 30, and adjusting the frictional force generated between the cutting tool and the adhesive layer 30 during cutting. This frictional force can be adjusted, for example, by adjusting the composition of the adhesive layer 30.

[0062] For example, a multilayer optical thin film X can be manufactured using the above method.

[0063] Example The following examples illustrate the present invention. The present invention is not limited to the examples. Furthermore, the specific values ​​of blending amount (content), physical property value, parameters, etc., described below can be replaced by the upper limit (values ​​defined as "below" or "less than") or lower limit (values ​​defined as "above" or "greater than") of the blending amount (content), physical property value, parameters, etc., corresponding to those described in the above "Forms for Implementing the Invention".

[0064] [Example 1] Mix the following ingredients at 25°C for 1 hour to prepare the adhesive composition.

[0065] 45 parts by weight of 3-phenoxybenzyl acrylate (brand name "LIGHT ACRYLATE POB-A", monomer, manufactured by Kyoei Chemical Co., Ltd.) 25 parts by weight of phenoxy diethylene glycol acrylate (brand name "LIGHT ACRYLATE P2H-A", monomer, manufactured by Kyoei Chemical Co., Ltd.) 5 parts by weight of 3-propylene glycol diacrylate (brand name "ARONIX M-220", monomer, manufactured by Toa Synthetic Co., Ltd.) 10 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate (brand name "ARONIX M-5700", monomer, manufactured by Toa Synthetic Co., Ltd.) 5 parts by weight of hydroxyethyl acrylamide (product name "HEAA", monomer, manufactured by KJ Chemicals Corporation) 5 parts by weight of diethylacrylamide (product name "DEAA", monomer, manufactured by KJ Chemicals Corporation) 3 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morphofolinylprop-1-one (brand name "OMINIRAD907", photopolymerization initiator, manufactured by IGM Resins) 3 parts by weight of 2,4-diethyl-9-oxosulfur (Product name "KAYACURE DETX-S", photopolymerization initiator, manufactured by Nippon Kayaku Co., Ltd.) 5 parts by weight of acrylic oligomer (brand name "ARUFON 1190", viscosity 6000 mPa·s (25℃), Mw 1700, Tg -50℃, manufactured by Toa Synthetic Co., Ltd.) 0.5 parts by weight of acrylonitrile-modified polydimethylsiloxane (brand name "BYK-UV3505", leveling agent, manufactured by BYK Corporation)

[0066] Next, an adhesive composition is coated onto a 23µm thick COP film (brand name "ZeonorFilm ZF14", manufactured by ZEON Corporation, Japan) serving as a transparent protective film, forming an adhesive coating film with a thickness of 1µm. Coating is performed using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd.) (groove shape: honeycomb, gravure roller line count 1000 lines / inch, rotation speed 140% / line speed). Next, a polarizing film is bonded to the transparent protective film through the adhesive coating film. Then, the adhesive coating film is cured by irradiating it with ultraviolet light from the transparent protective film side. For ultraviolet irradiation, an ultraviolet irradiation device equipped with a gallium-filled metal halide lamp (brand name "Light HAMMER10", bulb: V bulb, manufactured by Fusion UV Systems, Inc.) is used as the light source. Under ultraviolet irradiation, the peak illuminance was 1600 mW / cm², and the cumulative irradiation was set to 1000 mJ / cm² (wavelength 380~440 nm) (illuminance was measured using the "Sola-Check system" manufactured by Solatell). A multilayer optical film was then obtained by bonding a transparent protective film and a polarizing film. Next, the multilayer optical film underwent shaping. Specifically, the multilayer optical film was cut along its thickness direction by irradiation with a CO₂ laser to obtain a multilayer optical film with a predetermined top-view shape. During CO₂ laser irradiation, the wavelength was set to 9.4 µm, the output to 48 W, and the scanning speed to 500 mm / s. The multilayer optical film was then placed at room temperature for 24 hours.

[0067] Following the above method, the multilayer optical film of Example 1 was fabricated. The multilayer optical film of Example 1 has a polarizing film (thickness 5µm), an adhesive layer and a transparent protective film (thickness 23µm) sequentially formed in the thickness direction.

[0068] [Example 2] Except that the amount of one of the monomer components, "ARONIX M-220", was set to 2 parts by mass instead of 5 parts by mass, the multilayer optical film (polarizing film / adhesive layer / transparent protective film) of Example 2 was produced in the same manner as the multilayer optical film of Example 1.

[0069] [Example 3] Except that the amount of one of the monomer components, "ARONIX M-220", was set to 1 part by mass instead of 5 parts by mass, the multilayer optical film (polarizing film / adhesive layer / transparent protective film) of Example 3 was produced in the same manner as the multilayer optical film of Example 1.

[0070] [Comparative Example 1] Except that the amount of one of the monomer components, "ARONIX M-220", was set to 3 parts by mass instead of 5 parts by mass, the composite optical film (polarizing film / adhesive layer / transparent protective film) of Comparative Example 1 was prepared in the same manner as the composite optical film of Example 1.

[0071] <Indentation modulus> The indentation modulus of the adhesive layer in each laminated optical film of Examples 1-3 and Comparative Example 1 was determined by nanoindentation. Specifically, a 5mm × 10mm film sheet (laminated optical film) was first cut from the laminated optical film. Then, the laminated optical film was cut using the freeze-cutting method. Specifically, after cooling the laminated optical film to -30°C, it was cut along the thickness direction of the film with a hard cutter, and then restored to room temperature. This yielded the test sample. Next, using a nanoindentation testing machine (product name "TI950 Triboindenter", manufactured by Hysitron Corporation), the exposed surface of the adhesive layer in the test sample was subjected to load-displacement measurement according to JIS Z 2255:2003 to obtain the load-displacement curve. In this measurement, the measurement mode was set to single indentation measurement, the measurement temperature was set to 25℃, and a Berkovich (triangular pyramidal) diamond indenter was used. During load application, the maximum indentation depth (maximum displacement hmax) of the indenter on the test sample was set to 200 nm, the indentation speed was set to 10 nm / s, and the pull-out speed of the indenter from the test sample during unloading was set to 10 nm / s (first measurement condition). Then, the obtained measurement data were processed using the dedicated analysis software (Ver. 9.4.0.1) of the "TI950 Triboindenter". Specifically, based on the obtained load (f)-displacement (h) curve, the following were obtained: maximum load fmax (the load acting on the indenter with the maximum displacement hmax), contact projected area S (the projected area of ​​the contact region between the indenter and the sample at maximum load), and the slope D of the tangent line of the load-displacement curve at the start of unloading. Then, the indentation elastic modulus of the adhesive layer is calculated from the slope D and the contact projected area S (=(π 1 / 2D) / (2S 1 / 2)).

[0072] On the other hand, except that the maximum indentation depth was changed from 200 nm to 50 nm, load-displacement measurements were performed using a nanoindenter under the same measurement conditions as the first measurement condition (the second measurement condition). Then, the measurement data were processed using the dedicated analysis software (Ver. 9.4.0.1) of the "TI950 Triboindenter" to calculate the indentation elastic modulus of the adhesive layer.

[0073] <Observation of the End> The longitudinal cross-sectional shape of the ends of each laminated optical film of Examples 1-3 and Comparative Example 1 was investigated. Specifically, a longitudinal cross-section for observation was first formed by cutting along the thickness direction at an arbitrarily selected point from the periphery of the laminated optical film. Then, this longitudinal cross-section was observed and photographed using an optical microscope. In the observation cross-sections of each laminated optical film of Examples 1-3, it was confirmed that the end edge (side surface) of the adhesive layer was located further inward in the film surface direction than the end edge (first end edge) of the polarizing film and the end edge (second end edge) of the transparent protective film. In the observation cross-section of the laminated optical film of Comparative Example 1, it was confirmed that the end edge (side surface) of the adhesive layer was located further outward in the film surface direction than the end edge (first end edge) of the polarizing film and the end edge (second end edge) of the transparent protective film.

[0074] Furthermore, in each observation section, the receding length d1 of the adhesive layer side surface in the planar direction, measured from the edge of the polarizing film (first edge), and the receding length d2 of the adhesive layer side surface in the planar direction, measured from the edge of the transparent protective film (second edge), were measured. The results are shown in Table 1. Also shown in Table 1 is the recessed length L1 of the adhesive layer side surface, measured from the inner edge of the first and second edges in the planar direction (corresponding to the longer of the receding lengths d1 and d2). When the recessed length L1 is negative, the edge of the adhesive layer is located further outward in the planar direction than the edge of the polarizing film (first edge) and the edge of the transparent protective film (second edge). Then, regarding the prevention of end-bonding of the laminated optical film, cases with a recessed length L1 greater than 0 µm were evaluated as "good," and cases less than 0 µm were evaluated as "poor." The evaluation results are shown in Table 1.

[0075] Impact resistance Regarding the impact resistance of the laminated optical films of Examples 1-3 and Comparative Example 1, the condition in which neither the polarizing film nor the transparent protective film suffers damage (cracks, notches, etc.) in the above-mentioned observation cross-section is evaluated as "good", and the condition in which at least one of the polarizing film and the transparent protective film suffers damage is evaluated as "poor". The evaluation results are shown in Table 1.

[0076] [Table 1]

[0077] X: Multilayer optical thin film H: Thickness direction D: Inclined surface F: End face L1: Indentation length 10: Optical Thin Films (First Optical Thin Film) 10a: End 11: The edge (first edge) of the optical thin film 10 20: Optical Thin Film (Second Optical Thin Film) 20a: end 21: The second edge of the optical thin film 20 30: Adhesive layer 31, 31A, 31B: Side view 31a, 31b: End

Claims

1. A laminated optical thin film, comprising, in a thickness direction, a first optical thin film, an adhesive layer, and a second optical thin film sequentially thereon; the adhesive layer is bonded to the first optical thin film and to the second optical thin film; the adhesive layer has a side surface that is recessed further inward than a first edge of the first optical thin film and a second edge of the second optical thin film in a plane direction orthogonal to the thickness direction; the recessed length of the side surface is 1.0 µm or less, measured from the edge of the first or second edge located inward in the plane direction.

2. The laminated optical thin film of claim 1, wherein the recessed length of the side surface, measured from the end edge located inside the aforementioned surface direction of the aforementioned first end edge and the aforementioned second end edge, is 0.05µm or more.

Images