WO2022230889A1

WO2022230889A1 - Multilayer optical film

Info

Publication number: WO2022230889A1
Application number: PCT/JP2022/018916
Authority: WO
Inventors: 泰介笹川
Original assignee: 日東電工株式会社
Priority date: 2021-04-30
Filing date: 2022-04-26
Publication date: 2022-11-03
Also published as: JPWO2022230889A1; CN117042961A; KR20240002732A; TW202308845A

Abstract

A multilayer optical film (X) according to the present invention is sequentially provided with an optical film (10), an adhesive layer (30) and an optical film (20) in the thickness direction (H). The adhesive layer (30) is bonded to the optical film (10), while also being bonded to the optical film (20). The adhesive layer (30) has an extended end part (30a). The extended end part (30a) extends outwardly beyond an edge (11) of the optical film (10) and an edge (21) of the optical film (20) in a plane direction that is perpendicular to the thickness direction (H).

Description

laminated optical film

The present invention relates to a laminated optical film.

A display panel has a laminated structure including, for example, a pixel panel, a touch panel, and a surface protective cover. Various functional optical films having predetermined optical functions are also included in the laminated structure of the display panel. Functional optical films include, for example, polarizer films and retardation films. The functional optical film is incorporated in a laminated structure in the form of a laminated optical film, for example, in a state where it is bonded to another optical film such as a protective film via an adhesive. Such a laminated optical film is described, for example, in Patent Document 1 below.

JP 2019-147865 A

As display panels become thinner, optical films are becoming thinner. The thinner the optical film in the laminated optical film is, the more likely the edges of the laminated optical film are to be cracked or otherwise damaged by an external force. When a crack occurs at the edge of the laminated optical film, the crack grows, for example, extending to the inner region in the plane direction of the film. The occurrence of cracks at the edges causes such large cracks, which is undesirable. In addition, in a non-rectangular irregular-shaped display panel, since the display function is used up to the edge of the panel, suppression of edge cracks is strongly desired. Conventionally, in irregular-shaped display panels such as smartphones, due to long-term use of the device in which the panel is incorporated, minute cracks at the edge of the panel in the periphery of the irregular-shaped processing progress into the panel, causing bright lines on the device display screen. Cheap. There is a strong demand for suppression of such defects.

The present invention provides a laminated optical film suitable for suppressing damage to the edges of the optical film.

The present invention [1] is a laminated optical film comprising a first optical film, an adhesive layer, and a second optical film in order in the thickness direction, wherein the adhesive layer is bonded to the first optical film. and bonded to the second optical film, the adhesive layer has an extending edge, and the extending edge extends from the first optical film in a plane direction orthogonal to the thickness direction. A laminated optical film extending outwardly from one edge and a second edge of the second optical film.

In the present laminated optical film, as described above, the adhesive layer sandwiched between the first optical film and the second optical film has an extension end extending outward from both optical films. At a location where such an extended end portion exists, when an external member approaches and collides with the laminated optical film from the outside in the plane direction, the extended end portion extends further outward than both optical films. is subjected to collisions with external members. As a result, further approaching of the external member is prevented, and collision of the external member with the first edge of the first optical film and the second edge of the second optical film is prevented. Alternatively, if the external member collides with the first edge and/or the second edge, the impact force against these edges is mitigated. Such collision prevention and impact mitigation are suitable for suppressing damage to the edges of the optical film in the laminated optical film. In addition, the fact that the adhesive layer of the laminated optical film has an extended end is suitable for suppressing the occurrence and growth of microcracks at the ends of the first and second optical films.

The present invention [2] is the laminated optical system according to [1] above, wherein the first optical film is a polarizer film, and the first edge is outside the second edge in the plane direction. Including film.

Such a configuration is preferable for suppressing damage to the second edge of the second optical film in the laminated optical film.

The present invention [3] is the laminate according to [1] or [2] above, wherein the extending length of the extending end portion from the first edge in the surface direction is 0.01 μm or more and 5 μm or less Includes optical film.

Such a configuration is preferable for achieving both suppression of damage and suppression of peeling at the first edge of the first optical film.

The present invention [4] provides any one of [1] to [3] above, wherein the extending length of the extending end portion from the second edge in the planar direction is 0.03 μm or more and 10 μm or less. The laminated optical film described in 1.

Such a configuration is preferable for achieving both suppression of damage and suppression of peeling at the second edge of the second optical film.

In the present invention [5], the indentation modulus E1 at 25° C. of the adhesive layer and the indentation modulus E2 at 80° C. of the adhesive layer are 0.05≦E2/E1≦0.05. 25, the laminated optical film according to any one of the above [1] to [4].

Such a configuration is preferable for forming the above-described extended end portion when the laminated optical film is manufactured through film contour processing in which the end portion of the laminated optical film is heated.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of one Embodiment of the laminated optical film of this invention. 2 is an enlarged cross-sectional view of an end portion of the laminated optical film shown in FIG. 1; FIG. Represents a function of the extended end of the adhesive layer.

A laminated optical film X as an embodiment of the laminated optical film of the present invention comprises an optical film 10 (first optical film), an optical film 20 (second optical film), and an adhesive layer, as shown in FIG. 30. The laminated optical film X has a sheet shape with a predetermined thickness and spreads in a direction orthogonal to the thickness direction H (plane direction). Specifically, the laminated optical film X includes an optical film 10, an adhesive layer 30, and an optical film 20 in the thickness direction H in this order. The adhesive layer 30 bonds the

optical films

10 and 20 together. Also, the laminated optical film X is a composite film incorporated into the laminated structure of the display panel. The laminated optical film X may be in the form of a sheet or in the form of a roll.

The optical film 10 is a functional optical film in this embodiment. Functional optical films include, for example, polarizer films and retardation films.

A polarizer film includes, for example, a hydrophilic polymer film that has undergone a dyeing treatment with a dichroic substance and a subsequent stretching treatment. Dichroic substances include, for example, iodine and dichroic dyes. Hydrophilic polymer films include, for example, polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films. Polarizer films also include oriented polyene films. Materials for the oriented polyene film include, for example, dehydrated PVA and dehydrochlorinated polyvinyl chloride. As the polarizer film, a PVA film that has undergone a dyeing treatment with iodine and a subsequent uniaxial stretching treatment is preferable because it has excellent optical properties such as polarizing properties.

The thickness of the optical film 10 as a polarizer film is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less, from the viewpoint of thinning. A thin polarizer film has excellent visibility due to its small thickness unevenness, and is excellent in durability against thermal shock due to its small dimensional change due to temperature change. The thickness of the optical film 10 as a polarizer film is preferably 3 μm or more, more preferably 5 μm or more, from the viewpoint of strength.

Examples of retardation films include λ/2 wavelength films, λ/4 wavelength films, and viewing angle compensation films. Materials for the retardation film include, for example, polymer films birefringent by stretching. Polymeric films include, for example, cellulose films and polyester films. Cellulose films include, for example, triacetyl cellulose films. Polyester films include, for example, polyethylene terephthalate films and polyethylene naphthalate films. The thickness of the optical film 10 as a retardation film is, for example, 20 μm or more and, for example, 150 μm or less. As the retardation film, a film comprising a substrate such as a cellulose film and an orientation layer of a liquid crystal compound such as a liquid crystalline polymer on the substrate can also be preferably used.

The optical film 20 is a transparent protective film in this embodiment. The transparent protective film is, for example, a flexible transparent resin film. Materials for the transparent protective film include, for example, polyolefin, polyester, polyamide, polyimide, polyvinyl chloride, polyvinylidene chloride, cellulose, modified cellulose, polystyrene, and polycarbonate. Polyolefins include, for example, cycloolefin polymers (COP), polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers. Polyesters include, for example, polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Polyamides include, for example, polyamide 6, polyamide 6,6, and partially aromatic polyamides. Examples of modified cellulose include triacetyl cellulose. These materials may be used alone, or two or more of them may be used in combination. As a material for the transparent protective film, from the viewpoint of cleanliness, polyolefin is preferably used, and COP is more preferably used. Also, the optical film 20 is preferably a uniaxially stretched film or a biaxially stretched film.

From the viewpoint of the strength of the laminated optical film X, the thickness of the optical film 20 is preferably 5 µm or more, more preferably 10 µm or more, and even more preferably 20 µm or more. From the viewpoint of thinning the laminated optical film X, the thickness of the optical film 20 is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

The adhesive layer 30 is a cured adhesive composition. The adhesive layer 30 bonds directly to the optical film 10 and directly bonds to the optical film 20 . The adhesive composition contains a curable resin. The components of the adhesive composition are specifically described below.

From the viewpoint of bonding strength between the

optical films

10 and 20, the thickness T1 of the adhesive layer 30 is preferably 0.1 μm or more, more preferably 0.4 μm or more, even more preferably 0.7 μm or more, and particularly preferably 0 .8 μm or more. From the viewpoint of thinning the laminated optical film X, the thickness T1 of the adhesive layer 30 is preferably 5 μm or less, more preferably 3 μm or less, still more preferably 1.5 μm or less, and particularly preferably 1 μm or less.

At least part of the peripheral edge of the adhesive layer 30 has an extended end portion 30a, as shown in FIG. The extending end portion 30a extends outward ( In FIG. 2, it is a part extending leftward in the drawing. In the laminated optical film X, when the external member M approaches and collides with the laminated optical film X from the outside in the plane direction, as shown in FIG. , the extension end portion 30a extending outward from the

optical films

10 and 20 receives the collision of the external member M. As shown in FIG. As a result, further approach of the external member M is prevented, and collision of the external member M against the edge 11 of the optical film 10 and the edge 21 of the optical film 20 is prevented. Alternatively, even if the external member M collides with the edge 11 and/or the edge 21, the impact force against these

edges

11 and 21 is alleviated. Such collision prevention and collision force mitigation are suitable for suppressing damage to the edges of the

optical films

10 and 20 in the laminated optical film X. FIG. In addition, the fact that the adhesive layer 30 of the laminated optical film X has the extended end portion 30a is suitable for suppressing the occurrence and growth of microcracks at the end portions of the

optical films

10 and 20. FIG.

When the optical film 10 is a polarizer film and the optical film 20 is a transparent protective film, the edge 11 is preferably outside the edge 21 in the plane direction. Such a configuration is preferable for suppressing damage to the edge 21 of the optical film 20 in the laminated optical film X.

The extension length L1 of the extension end portion 30a from the edge 11 in the surface direction is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm, and particularly preferably 0.3 μm or more. is. Such a configuration is preferable for suppressing damage to the edge 11 of the optical film 10 . Also, the extension length L1 is preferably 8 μm or less, more preferably 5 μm or less, even more preferably 4 μm or less, still more preferably 3 μm, and particularly preferably 1 μm or less. Such a configuration is preferable for suppressing the occurrence of adhesive residue on the edge of the panel due to the excessively extended adhesive when the laminated optical film X is incorporated into a display panel of a smartphone or the like. , it is preferable to suppress the display unevenness caused by the adhesive residue. The extension length L1 is specifically the distance in the surface direction between the edge 11 of the optical film 10 and the edge 31 of the adhesive layer 30 .

The extension length L2 of the extension end portion 30a from the edge 21 in the plane direction is preferably 0.03 μm or more, more preferably 0.1 μm or more, still more preferably 0.3 μm, and particularly preferably 0.5 μm or more. is. Such a configuration is preferable for suppressing damage to the edge 21 of the optical film 20 . Also, the extension length L2 is preferably 10 μm or less, more preferably 7 μm or less, still more preferably 5 μm, and particularly preferably 3 μm or less. Such a configuration is preferable for suppressing peeling from the adhesive layer 30 at the edge 21 of the optical film 20 . The extension length L2 is specifically the distance in the surface direction between the edge 21 of the optical film 20 and the edge 31 of the adhesive layer 30 .

The ratio (L2/L1) of the extension length L2 to the extension length L1 is preferably 1.1 or more, more preferably 1.5 or more, still more preferably 2 or more, and particularly preferably 2.5 or more. . The ratio (L2/L1) is preferably 10 or less, more preferably 8 or less, even more preferably 7 or less, and particularly preferably 5 or less. These configurations are preferable for achieving both the above-described suppression of damage and suppression of peeling of the

optical films

10 and 20 .

The indentation elastic modulus (indentation elastic modulus E1) of the adhesive layer 30 at 25° C. measured by the nanoindentation method is preferably 0.5 GPa or more, more preferably 1 GPa or more, still more preferably 1.5 GPa or more, Particularly preferably, it is 2 GPa or more. Such a configuration is preferable from the viewpoint of securing the bonding strength between the

optical films

10 and 20 . In addition, such a configuration is preferable for ensuring the above-described collision prevention and collision force mitigation functions of the extension end portion 30a, and for achieving both the above-described damage suppression and peeling suppression in the

optical films

10 and 20. Helpful. The indentation modulus E1 is preferably 7 GPa or less, more preferably 5 GPa or less, and even more preferably 3 GPa or less. Such a configuration is preferable for ensuring flexibility of the adhesive layer 30 when the laminated optical film X is used for a repeatedly foldable display panel. Methods for adjusting the indentation modulus of the adhesive layer 30 include, for example, adjusting the composition of the adhesive composition. Specifically, the adjustment of the number of functional groups of the polymerizable compound described later in the adhesive composition forming the adhesive layer 30, that is, the adjustment of the acrylic equivalent and epoxy equivalent of the polymerizable compound, is effective for the pressing of the adhesive layer 30. It is effective as an elastic modulus adjustment method.

The nanoindentation method is a technique for measuring various physical properties of samples on a nanometer scale. In this embodiment, the nanoindentation method is performed in compliance with ISO14577. In the nanoindentation method, a process of pushing an indenter into a sample set on a stage (loading process) and then a process of withdrawing the indenter from the sample (unloading process) are performed. The load acting between the indenter and the sample and the relative displacement of the indenter with respect to the sample are measured (load-displacement measurement). This makes it possible to obtain a load-displacement curve. From this load-displacement curve, it is possible to obtain various physical properties of the measurement sample based on nanometer scale measurement. For example, a nanoindenter (trade name “Triboindenter”, manufactured by Hysitron) can be used for the load-displacement measurement of the cross section of the adhesive layer by the nanoindentation method. Specifically, it is as described later with respect to Examples.

The indentation elastic modulus (indentation elastic modulus E2) of the adhesive layer 30 at 80° C. measured by the nanoindentation method is preferably 0.05 GPa or more, more preferably 0.1 GPa or more, and still more preferably 0.2 GPa. More preferably, it is 0.3 GPa or more. Such a configuration is preferable for suppressing heat shrinkage of the adhesive layer 30 and forming the extension end portion 30a during the later-described film contour processing when the temperature of the end portion of the laminated optical film X rises. From the viewpoint of the processing resistance of the adhesive layer 30, the indentation modulus E2 is preferably 0.7 GPa or less, more preferably 0.5 GPa or less, and even more preferably 0.4 GPa or less.

The indentation elastic moduli E1 and E2 preferably satisfy 0.05≦E2/E1≦0.25. Such a configuration is preferable for suppressing heat shrinkage of the adhesive layer 30 and forming the extension end portion 30a during the later-described film contour processing when the temperature of the end portion of the laminated optical film X rises. The value of E2/E1 is more preferably 0.1 or more, still more preferably 0.12 or more, and more preferably 0.2 or less, still more preferably 0.18 or less.

In the laminated optical film X, the 90° peel strength of the optical film 20 to the optical film 10 at 25°C is preferably 1 N/15 mm or more, more preferably 1.2 N/15 mm or more, and still more preferably 1.5 N/15 mm or more. is. Such a configuration is preferable for achieving good bonding strength between the

optical films

10 and 20, and particularly preferable for ensuring bonding strength between the

optical films

10 and 20 for a foldable display panel. The 90° peel strength is, for example, 10 N/15 mm or less. The 90° peel strength can be measured using, for example, a Tensilon universal tester (product name: "RTC", manufactured by A&D). In this measurement, the measurement temperature is 25° C., the peeling angle is 90°, and the peeling speed is 1000 mm/min. Moreover, as a method for adjusting the 90° peel strength, for example, adjustment of the composition of the adhesive composition can be mentioned. Specific examples of the method for adjusting the 90° peel strength include adjustment of the number of functional groups of the polymerizable compound described later in the adhesive composition, that is, adjustment of the acrylic equivalent and epoxy equivalent of the polymerizable compound.

The ratio of the 90° peel strength (N/15mm) to the indentation modulus E2 (GPa) described above is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, and preferably 30 or less, more It is preferably 25 or less. Such a configuration is preferable from the standpoint of processing resistance of the adhesive layer 30 .

The adhesive layer 30 is, for example, a cured product of an adhesive composition (active energy ray-curable composition) containing an active energy ray-curable resin. Active energy ray-curable compositions include, for example, electron beam-curable compositions, UV-curable compositions, and visible light-curable compositions. In addition, the active energy ray-curable composition is either one or both of a radically polymerizable composition and a cationic polymerizable composition in the present embodiment.

When the active energy ray-curable composition is a radically polymerizable composition, the composition contains a radically polymerizable compound as a monomer. A radically polymerizable compound is a compound having a radically polymerizable functional group. Examples of radically polymerizable functional groups include ethylenically unsaturated bond-containing groups. Ethylenically unsaturated bond-containing groups include, for example, (meth)acryloyl groups, vinyl groups, and allyl groups. A (meth)acryloyl group means an acryloyl group and/or a methacryloyl group. From the viewpoint of curability of the active energy ray-curable composition, the active energy ray-curable composition preferably contains a radically polymerizable compound having a (meth)acryloyl group as a main component. A main component means the component with the largest mass ratio. The proportion of the (meth)acryloyl group-containing radically polymerizable compound in the active energy ray-curable composition is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. Moreover, the radically polymerizable compound includes a monofunctional radically polymerizable compound and a difunctional or higher polyfunctional radically polymerizable compound.

Examples of monofunctional radically polymerizable compounds include (meth)acrylamide derivatives having a (meth)acrylamide group. (Meth)acrylamide derivatives include N-alkyl group-containing (meth)acrylamide derivatives, N-hydroxyalkyl group-containing (meth)acrylamide derivatives, N-aminoalkyl group-containing (meth)acrylamide derivatives, N-alkoxy group-containing (meth)acrylamide derivatives, ) acrylamide derivatives and N-mercaptoalkyl group-containing (meth)acrylamide derivatives. N-alkyl group-containing (meth)acrylamide derivatives include, for example, 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, preferably N,N-diethylacrylamide is used. N-hydroxyalkyl group-containing (meth)acrylamide derivatives include, for example, N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-methylol-N-propane(meth)acrylamide, preferably is N-hydroxyethyl acrylamide. The (meth)acrylamide derivatives may be used alone, or two or more of them may be used in combination.

Examples of monofunctional radically polymerizable compounds include (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Examples of the (meth)acrylic acid derivative include (meth)acrylic acid alkyl esters and (meth)acrylic acid derivatives other than (meth)acrylic acid alkyl esters. The (meth)acrylic acid derivatives may be used alone, or two or more of them may be used in combination.

(Meth)acrylic acid alkyl esters include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, ) acrylate, n-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl- 2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

Examples of (meth)acrylic acid derivatives other than (meth)acrylic acid alkyl esters include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid aralkyl esters, hydroxyl group-containing (meth)acrylic acid derivatives, alkoxy group-containing ( Examples include meth)acrylic acid derivatives and phenoxy group-containing (meth)acrylic acid derivatives. (Meth)acrylic acid cycloalkyl esters include, for example, cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate. (Meth)acrylic acid aralkyl esters include, for example, benzyl (meth)acrylate and 3-phenoxybenzyl (meth)acrylate. Examples of hydroxyl group-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]methyl acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. Alkoxy group-containing (meth)acrylic acid derivatives include, for example, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate. Phenoxy group-containing (meth)acrylic acid derivatives include, for example, phenoxyethyl (meth)acrylate and phenoxydiethylene glycol (meth)acrylate. The (meth)acrylic acid derivative other than the (meth)acrylic acid alkyl ester is preferably at least one selected from the group consisting of 3-phenoxybenzyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and phenoxydiethylene glycol acrylate. one is used.

　Carboxyl group-containing monomers are also included as monofunctional radically polymerizable compounds. Carboxyl group-containing monomers include, for example, (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

　The monofunctional radically polymerizable compound also includes a lactam-based vinyl monomer. Lactamic vinyl monomers include, for example, N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone.

Examples of monofunctional radically polymerizable compounds include vinyl-based monomers having nitrogen-containing heterocycles. Such monomers include, for example, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

Examples of polyfunctional radically polymerizable compounds include tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate. ) acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclic trimethylol propane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are used, preferably tripropylene glycol diacrylate. The polyfunctional radically polymerizable compounds may be used alone, or two or more of them may be used in combination. A polyfunctional radically polymerizable compound functions as a cross-linking agent.

When the active energy ray-curable composition is an ultraviolet curable composition or a visible light curable composition, the active energy ray curable composition preferably contains a photopolymerization initiator. Photoinitiators include, for example, benzophenone compounds, benzoin ether compounds, and thioxanthone compounds. Benzophenone compounds include, for example, benzyl, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone. Benzoin ether compounds include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin butyl ether. Thioxanthone compounds include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

When the active energy ray-curable composition is a visible light-curable composition, a photopolymerization initiator that is highly sensitive to light of 380 nm or longer is preferably used. Such photopolymerization initiators include, for example, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morphol linophenyl)-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-pyrrol-1-yl)-phenyl)titanium.

As the photopolymerization initiator, 2,4-diethylthioxanthone and/or 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one are preferably used.

The content of the photopolymerization initiator in the active energy ray-curable composition is preferably 0.1 parts by mass or more, more preferably 0.05 parts by mass with respect to 100 parts by mass of the curable component (radical polymerizable compound). Above, more preferably 0.1 parts by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

When the active energy ray-curable composition is a cationic polymerizable composition, the composition contains a cationic polymerizable compound as a monomer. The cationically polymerizable compound is a compound having a cationically polymerizable functional group, and includes a monofunctional cationically polymerizable compound having one cationically polymerizable functional group and a polyfunctional cationically polymerizable compound having two or more cationically polymerizable functional groups. compounds. A monofunctional cationic polymerizable compound has a relatively low liquid viscosity. By adding such a monofunctional cationically polymerizable compound to the resin composition, the viscosity of the resin composition can be lowered. In addition, monofunctional cationically polymerizable compounds often have functional groups that exhibit various functions. By incorporating such a monofunctional cationically polymerizable compound into the resin composition, various functions can be expressed in the resin composition and/or the cured product of the resin composition. On the other hand, by curing the resin composition containing the polyfunctional cationically polymerizable compound, a cured product having a three-dimensional crosslinked portion is obtained (the polyfunctional cationically polymerizable compound functions as a crosslinking agent). From such a point of view, it is preferable to use polyfunctional cationically polymerizable compounds. When a monofunctional cationically polymerizable compound and a polyfunctional cationically polymerizable compound are used in combination, the amount of the polyfunctional cationically polymerizable compound relative to 100 parts by weight of the monofunctional cationically polymerizable compound is, for example, 10 parts by weight or more. It is 1000 mass parts or less. Cationic polymerizable functional groups include, for example, epoxy groups, oxetanyl groups, and vinyl ether groups. Compounds having an epoxy group include, for example, aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. As the compound having an epoxy group, an alicyclic epoxy compound is preferably used from the viewpoint of curability and adhesiveness of the cationic polymerizable composition. The alicyclic epoxy compounds include, for example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, or caprolactone-modified 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, Examples include trimethylcaprolactone-modified products and valerolactone-modified products. Examples of commercially available alicyclic epoxy compounds include Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2083, and Celoxide 2085 (manufactured by Daicel Chemical Industries, Ltd.), and Cyracure UVR-6105. , Cyracure UVR-6107, Cyracure 30, and R-6110 (manufactured by Dow Chemical Japan). From the viewpoint of improving curability and reducing viscosity of the cationic polymerizable composition, it is preferable to use a compound having an oxetanyl group and/or a compound having a vinyl ether group. Compounds having an oxetanyl group include, for example, 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. Commercially available compounds having an oxetanyl group include, for example, Aron oxetane OXT-101, Aron oxetane OXT-121, Aron oxetane OXT-211, Aron oxetane OXT-221, and Aron oxetane OXT-212 (manufactured by Toagosei Co., Ltd.). is mentioned. Examples of compounds having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol vinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclo. Decane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and pentaerythritol type tetravinyl ether.

When the active energy ray-curable composition is an ultraviolet curable composition or a visible light curable composition, the active energy ray curable composition contains a photocationic polymerization initiator. A photocationic polymerization initiator generates cationic species or Lewis acid upon irradiation with active energy rays (visible light, ultraviolet rays, X-rays, electron beams, etc.) and initiates the polymerization reaction of the cationic polymerizable functional groups. The photocationic polymerization initiator includes a photoacid generator and a photobase generator, preferably a photoacid generator. When the active energy ray-curable composition is used as a visible light-curable composition, it is preferable to use a cationic photopolymerization initiator that is particularly sensitive to light of 380 nm or longer. Moreover, when a photocationic polymerization initiator is used, it is preferable to use together a photosensitizer showing maximum absorption of light having a wavelength longer than 380 nm. A photocationic polymerization initiator is generally a compound that exhibits maximum absorption in a wavelength region near or shorter than 300 nm. Long wavelength light can be effectively used to promote the generation of cationic species or Lewis acids from the photocationic polymerization initiator. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes. These may be used alone, or two or more of them may be used in combination. In particular, an anthracene compound is preferable because of its excellent photosensitizing effect. Commercially available anthracene compounds as photosensitizers include, for example, Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Kasei Co., Ltd.). The content of the photosensitizer in the composition is, for example, 0.1 to 5% by weight.

The active energy ray-curable composition may contain an oligomer. Oligomers include acrylic oligomers, fluorine oligomers, and silicone oligomers, preferably acrylic oligomers. Incorporation of the oligomer into the active energy ray-curable composition is useful for suppressing shrinkage of the composition upon curing. Suppression of cure shrinkage of the active energy ray-curable composition is preferable for reducing interfacial stress between the formed adhesive layer 30 and the

optical films

10 and 20 . Suppression of interfacial stress is useful for securing bonding strength between the

optical films

10 and 20 .

Examples of (meth)acrylic monomers that form acrylic oligomers include (meth)acrylic acid alkyl esters having 1 to 20 carbon atoms, cycloalkyl (meth)acrylates, aralkyl (meth)acrylates, polycyclic (meth)acrylates, Examples include hydroxyl group-containing (meth)acrylic acid esters and halogen-containing (meth)acrylic acid esters. (Meth)acrylic acid alkyl esters, for example, 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. Cycloalkyl (meth)acrylates include, for example, cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate. Aralkyl (meth)acrylates include, for example, benzyl (meth)acrylate. Polycyclic (meth)acrylates include, for example, 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, and 3-methyl- 2-Norbornylmethyl (meth)acrylate can be mentioned. Examples of hydroxyl group-containing (meth)acrylic acid esters include hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate. Halogen-containing (meth)acrylic acid esters include, for example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate. These (meth)acrylates may be used alone, or two or more of them may be used in combination.

The weight average molecular weight (Mw) of the acrylic oligomer is preferably 15,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less. Mw of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more.

The content of the acrylic oligomer in the active energy ray-curable composition is preferably 2% by mass or more, more preferably 4% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less. .

The active energy ray-curable composition may contain other components. Other ingredients include silane coupling agents, leveling agents, surfactants, plasticizers, and UV absorbers. The blending amount of the other component is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less with respect to 100 parts by mass of the curable component. Part by mass or more.

The viscosity of the active energy ray-curable composition at 25° C. is preferably 3 mPa·s or more, more preferably 5 mPa·s or more, and still more preferably 10 mPa·s or more, from the viewpoint of coatability in the coating step described later. and is preferably 100 mPa·s or less, more preferably 50 mPa·s or less, and still more preferably 30 mPa·s or less. The viscosity of the composition is a value measured with an E-type viscometer (cone plate type viscometer).

The laminated optical film X can be produced, for example, as follows.

First, an active energy ray-curable composition is applied to one side (surface to be bonded) of one optical film (optical film 10 or optical film 20) to form a coating film of the composition (application step). Prior to this coating step, the surface to be bonded of the optical film may be subjected to a surface modification treatment. Surface modification treatments include corona treatment, plasma treatment, excimer-treatment, and flame treatment. Examples of coating methods in this step include reverse coaters, gravure coaters, bar reverse coaters, roll coaters, die coaters, bar coaters, and rod coaters.

Next, the other optical film (optical film 20 or optical film 10) is attached to one optical film via the composition coating film. For lamination, for example, a roll laminator can be used.

Next, the composition coating film between the

optical films

10 and 20 is irradiated with an active energy ray to cure the coating film (active energy ray-curable composition) to form the adhesive layer 30 (adhesion The adhesive layer 30 is not a pressure sensitive adhesive layer). As a result, the

optical films

10 and 20 are joined via the adhesive layer 30, and the raw material film of the laminated optical film X is obtained. In this step, from the viewpoint of suppressing deterioration of the optical film 10 as a functional optical film, it is preferable to irradiate the active energy ray from the optical film 30 side. Electron beams, ultraviolet rays, and visible rays can be used as active energy rays. Examples of electron beam irradiation means include an electron beam accelerator. Ultraviolet and visible light sources include, for example, 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 cut filter for cutting a part of the wavelength range of ultraviolet rays and/or visible light emitted from the light source may be used as needed.

Next, at least a portion of the peripheral edge of the raw material film is contoured (outer contouring step). For example, one longitudinal end of a roll-shaped raw material film is trimmed. For example, a roll-shaped raw material film is cut into sheets. Examples of these contour processing methods include laser processing such as CO ₂ laser irradiation, cutting with a punch blade, and end mill processing. Relatively large heat shrinkage occurs in the

optical films

10 and 20 at the portion of the raw material film where the outer shape is processed, and the extended end portion 30a is formed. Specifically, the

edges

11 and 21 of the

optical films

10 and 20 are retracted from the edge 31 of the adhesive layer 30 inward in the plane direction at the edges of the raw material film. It contracts to form the extended end 30a. The length of shrinkage of the ends of the

optical films

10 and 20, that is, the extension lengths L1 and L2 of the extension end portion 30a, depends on the material (dimensional shrinkage rate) and thickness of the

optical films

10 and 20 and the processing conditions. can be adjusted by adjusting Processing conditions include, for example, adjustment of the draw ratio.

For example, the laminated optical film X can be manufactured as described above.

The present invention will be specifically described below with reference to examples. The invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), physical property values, parameters, etc. described below are the corresponding compounding amounts ( content), physical properties, parameters, etc., upper limits (values defined as “less than” or “less than”) or lower limits (values defined as “greater than” or “greater than”).

[Example 1]
The following components were mixed at 25° C. for 1 hour to prepare an adhesive composition (preparation step).

45 parts by mass of 3-phenoxybenzyl acrylate (product name “Light Acrylate POB-A”, monomer, manufactured by Kyoeisha Chemical Co., Ltd.)
25 parts by mass of phenoxydiethylene glycol acrylate (product name “Light Acrylate P2H-A”, monomer, manufactured by Kyoeisha Chemical Co., Ltd.)
15 parts by mass of tripropylene glycol diacrylate (product name "Aronix M-220", monomer, manufactured by Toagosei Co., Ltd.)
10 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate (product name "Aronix M-5700", monomer, manufactured by Toagosei Co., Ltd.)
5 parts by mass of hydroxyethyl acrylamide (product name "HEAA", monomer, manufactured by KJ Chemicals)
5 parts by mass of diethylacrylamide (product name "DEAA", monomer, manufactured by KJ Chemicals)
3 parts by mass of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (product name "OMINIRAD907", photopolymerization initiator, manufactured by IGM Resins)
3 parts by mass of 2,4-diethylthioxanthone (product name “KAYACURE DETX-S”, photopolymerization initiator, manufactured by Nippon Kayaku Co., Ltd.)
5 parts by mass of acrylic oligomer (product name “ALPHON 1190”, viscosity 6000 mPa s (25 ° C.), Mw 1700, Tg −50 ° C., manufactured by Toagosei Co., Ltd.)
0.5 parts by mass of modified polydimethylsiloxane having an acrylic group (product name "BYK-UV3505", leveling agent, manufactured by BYK)

Next, the adhesive composition was applied onto a 23 μm thick COP film (product name “Zeonor Film ZF14”, manufactured by Nippon Zeon Co., Ltd.) as a transparent protective film to form an adhesive coating film of 1 μm thick. . For coating, an MCD coater (manufactured by Fuji Machine Co., Ltd.) (cell shape: honeycomb, gravure roll number of lines: 1000 lines/inch, rotation speed: 140%/line speed) was used. Next, the polarizer film was attached to the transparent protective film via the adhesive coating film on the same film. Next, the adhesive coating between the films was cured by irradiating the adhesive coating with ultraviolet rays from the transparent protective film side. For ultraviolet irradiation, an ultraviolet irradiation apparatus (product name: "Light HAMMER10", bulb: V bulb, manufactured by Fusion UV Systems, Inc.) equipped with a gallium-encapsulated metal halide lamp as a light source was used. In UV irradiation, the peak illuminance was 1600 mW/cm ² and the cumulative irradiance was 1000 mJ/cm ² (wavelength 380 to 440 nm) (illuminance was measured using the “Sola-Check system” manufactured by Solatell. ). As a result, the transparent conductive film and the polarizer film were bonded to obtain a laminated optical film.

Next, the laminated optical film was subjected to external processing (external processing step). Specifically, the laminated optical film was cut in the thickness direction by irradiation with a CO ₂ laser to obtain a laminated optical film having a predetermined plan view shape. In the CO ₂ laser irradiation, the wavelength was 9.4 μm, the power was 48 W, and the scanning speed was 500 mm/sec. The laminated optical film was then left at room temperature for 24 hours.

The laminated optical film of Example 1 was produced as described above. The laminated optical film of Example 1 includes a polarizer film (5 μm thick), an adhesive layer, and a transparent protective film (23 μm thick) in this order in the thickness direction.

[Example 2]
A laminated optical film (polarizer film/adhesive layer/transparent protective film) of Example 2 was produced in the same manner as the laminated optical film of Example 1 except for the following. In the preparation process, the blending amount of “Aronix M-220” was changed from 15 parts by weight to 5 parts by weight, and the thickness of the adhesive layer coating film formed on the transparent protective film was set to 1 μm.

[Example 3]
A laminated optical film (polarizer film/second adhesive layer/transparent protective film) of Example 3 was produced in the same manner as the laminated optical film of Example 1 except for the following.

In the preparation process, the blending amount of “light acrylate POB-A” was 43 parts by mass, the blending amount of “light acrylate P2H-A” was 29 parts by mass, and the blending amount of “Aronix M-220” was 3 parts by mass. did. In the coating step, the thickness of the adhesive layer coating film formed on the transparent protective film was set to 1 μm.

[Comparative Example 1]
A laminated optical film (polarizer film/adhesive layer/transparent protective film) of Comparative Example 1 was produced in the same manner as the laminated optical film of Example 1 except for the following.

In the preparation process, instead of "light acrylate POB-A" and "light acrylate P2H-A", 36 parts by mass of "light acrylate 1.9ND-A" (1,9-nonanediol diacrylate) manufactured by Kyoeisha Chemical Co., Ltd. And, using 12.5 parts by mass of “Light Acrylate HPP-A” (neopentyl glycol hydroxypivalate glycol acrylic acid adduct) manufactured by Kyoeisha Chemical Co., without using “Aronix M-220”, “Aronix M-5700 ” is 22 parts by mass, the amount of “HEAA” is 12.5 parts by mass, the amount of “DEAA” is 6 parts by mass, the amount of “HEAA” is 12.5 parts by mass, The blending amount of "ALPHON 1190" was set to 10 parts by mass.

<Observation of edge>
With respect to each of the laminated optical films of Examples 1 to 3 and Comparative Example 1, the vertical cross-sectional shape of the edge portion was examined. First, a longitudinal section for observation was formed by cutting a portion arbitrarily selected from the peripheral edge of the laminated optical film in the thickness direction. Next, the longitudinal section was observed and photographed with an optical microscope. Then, in each observed cross section, the portion where the adhesive layer extends outward from the edge (first edge) of the polarizer film and the edge (second edge) of the transparent protective film in the film plane direction (Extension end) was confirmed. Further, in each observation section, the extension length L1 of the extension end from the first edge in the plane direction and the extension length L2 of the extension end from the second edge in the plane direction are It was measured. Table 1 shows the results.

In addition, regarding the suppression of damage to the laminated optical film, the case where both the polarizer film and the transparent protective film had no damage (such as cracks and chips) in the above observation cross section was evaluated as "good". The evaluation was made on the basis of the criteria for evaluating "poor" when at least one of the transparent protective films was damaged. Table 1 shows the results.

<Indentation modulus>
The indentation elastic modulus of the adhesive layer in each of the laminated optical films of Examples 1 to 3 and Comparative Example 1 was measured by the nanoindentation method (first elastic modulus measurement). Specifically, first, a film piece (laminated optical film) having a size of 5 mm×10 mm was cut out from the laminated optical film. Next, the laminated optical film was cut by a cryomicrotome method. Specifically, the laminated optical film was cooled to −30° C., cut with a hard knife in the thickness direction of the same film, and then returned to room temperature. Thus, a sample for measurement was obtained. Next, using a nanoindenter (product name “TI950 Triboindenter”, manufactured by Hysitron), load-displacement measurement on the exposed surface of the adhesive layer in the measurement sample was performed in accordance with JIS Z 2255:2003. - A displacement curve was obtained. In this measurement, the measurement mode is single indentation measurement, the measurement temperature is 25 ° C., the indenter used is a Berkovich (triangular pyramid) type diamond indenter, and the maximum indentation depth (maximum The displacement hmax) was 50 nm, the indentation speed was 10 nm/sec, and the indenter withdrawal speed was 10 nm/sec during the unloading process. Then, the obtained measurement data was processed by dedicated analysis software (Ver. 9.4.0.1) of "TI950 Triboindenter". Specifically, based on the obtained load (f)-displacement (h) curve, the maximum load fmax (the load acting on the indenter at the maximum displacement hmax) and the projected contact area S (the indenter and sample at the maximum load and the slope D of the tangent to the load-displacement curve at the beginning of the unloading process. Then, from the slope D and the contact projected area S, the indentation elastic modulus (=(π ^1/2 D)/(2S ^1/2 )) of the adhesive layer was calculated. The value is shown in Table 1 as indentation elastic modulus E1 (GPa).

Further, the indentation elastic modulus at 80° C. of the adhesive layer in each of the laminated optical films of Examples 1 to 3 and Comparative Example 1 was the first elastic modulus except that the measurement temperature was changed to 80° C. instead of 25° C. It was measured in the same manner as the measurement (second elastic modulus measurement). The value is shown in Table 1 as indentation elastic modulus E2 (GPa). Table 1 also shows the ratio (E2/E1) of the indentation modulus E2 at 80°C to the indentation modulus E1 at 25°C.

The laminated optical film of the present invention can be used, for example, as an element included in the laminated structure of a display panel such as a foldable display panel.

X laminated optical film H thickness direction 10 optical film (first optical film)
11 edge (first edge)
20 optical film (second optical film)
21 edge (second edge)
30 Adhesive layer 30a Extension end 31 Edge

Claims

A laminated optical film comprising a first optical film, an adhesive layer, and a second optical film in order in the thickness direction,
the adhesive layer bonds to the first optical film and bonds to the second optical film;
The adhesive layer has an extending edge, and the extending edge extends from the first edge of the first optical film and the second edge of the second optical film in a plane direction orthogonal to the thickness direction. A laminated optical film extending outwardly beyond an edge.
The laminated optical film according to claim 1, wherein the first optical film is a polarizer film, and the first edge is outside the second edge in the plane direction.
2. The laminated optical film according to claim 1, wherein the extended length of said extended end portion from said first edge in said surface direction is 0.01 μm or more and 5 μm or less.
2. The laminated optical film according to claim 1, wherein the extended length of said extended end portion from said second edge in said surface direction is 0.03 μm or more and 10 μm or less.
2. The indentation elastic modulus E1 at 25° C. of the adhesive layer and the indentation elastic modulus E2 at 80° C. of the adhesive layer satisfy 0.05≦E2/E1≦0.25. 5. The laminated optical film according to any one of 4 to 4.