WO2023157406A1

WO2023157406A1 - Optical laminate and image display device

Info

Publication number: WO2023157406A1
Application number: PCT/JP2022/042566
Authority: WO
Inventors: 亮菅野; 昌之岡本; かおる ▲黒▼原
Original assignee: 日東電工株式会社
Priority date: 2022-02-17
Filing date: 2022-11-16
Publication date: 2023-08-24
Also published as: TW202333950A; JP2023119830A

Abstract

An optical laminate obtained by laminating an optical functional layer and a base film with an adhesive layer therebetween, said optical laminate characterized in that the thickness of the optical functional layer is 0.5 to 5 μm, the thickness of the adhesive layer is 0.5 to 3 μm, the adhesive layer is formed from a cured layer of an active energy ray-curable resin composition, and the glass transition temperature of the cured layer is less than 30°C.

Description

Optical laminate and image display device

The present invention relates to an optical laminate. The optical layered body can form an image display device such as a liquid crystal display (LCD) or an organic EL display.

In recent years, image display devices represented by liquid crystal display devices and organic EL display devices have spread rapidly. Conventionally, most image display devices have flat display screens, but in recent years, image display devices whose display screens can be curved, bent, folded, or rolled up have been developed. A display screen is usually formed of an optical laminate in which a plurality of optical films are laminated. For example, in the case of a foldable display screen, the adhesion between the laminated optical film and the adhesive layer is excellent. Otherwise, peeling or cracking may occur, especially in a humid environment, which may lead to product failure.

Patent Document 1 below discloses a laminated film having a laminated liquid crystal layer obtained by laminating at least two liquid crystal layers on one side of a base film with an adhesion-imparting layer interposed therebetween, wherein each liquid crystal layer is formed by the adhesion-imparting layer. describes an infrared reflective film in which the orientation of the

Patent Document 2 below describes a method for manufacturing a half mirror used on the surface of an image display portion of an image display device, wherein the half mirror includes a circularly polarized light reflecting layer, an adhesive layer and a transparent substrate in this order, and the circularly polarized light reflecting layer is It includes a cholesteric liquid crystal layer, and the manufacturing method includes preparing a transfer material including a circularly polarized light reflecting layer, bonding the surface of the circularly polarized light reflecting layer of the transfer material and a transparent substrate with a curable adhesive, and A production method is described which includes curing an adhesive to form the adhesive layer having a thickness of 1 μm or more and 5 μm or less, and wherein the pencil hardness of the surface of the transfer material to be bonded to the transparent substrate is HB or less.

Patent Document 3 below describes a laminate composed at least of a support substrate/adhesive layer/cholesteric liquid crystal layer/ultraviolet absorption layer, wherein the cholesteric liquid crystal layer has a cholesteric liquid crystal layer partially having a region exhibiting diffraction ability. Optical laminates composed of optical films are described.

Patent Document 4 below discloses a base layer having a first main surface and a second main surface, an adhesive layer provided in contact with the first main surface of the base layer, and a liquid crystal composition provided in contact with the adhesive layer. and a material-curing layer, wherein the substrate layer is made of a resin containing a polymer containing an alicyclic structure, and the first main surface of the substrate layer has a water contact angle of 80° or less. The adhesive layer is made of a cured product of an ultraviolet-curable resin composition, the ultraviolet-curable resin composition contains hydroxyalkyl acrylate as a main component, and the liquid crystal composition cured layer is a cured liquid crystal composition containing a liquid crystal compound. Laminates are described, consisting of objects.

JP 2013-158970 A Japanese Patent Application Laid-Open No. 2016-224292 JP-A-2000-304927 JP 2019-188740 A

The technology described in the above patent document does not originally envision applications for display screens that can be curved, bent, bent, or rolled up. In addition, as a result of intensive studies by the present inventors, in the technique described in the above patent document, when the optical laminate is folded, the adhesive layer maintains the adhesion between the adherend (optical film). Turns out it wasn't possible.

The present invention has been developed in view of the above circumstances, and the optical film exhibits excellent adhesion between the optical film and the adhesive layer and crack resistance of the optical film even in a humidified environment, especially when the adhesive layer is folded. An object of the present invention is to provide an optical layered body provided with an adhesive layer capable of improving properties, and an image display device using the optical layered body.

The above issues can be resolved by the following configuration. That is, the present invention provides an optical laminate in which an optical functional layer and a base film are laminated via an adhesive layer, wherein the optical functional layer has a thickness of 0.5 to 5 μm, and the adhesive layer has a thickness of 0.5 to 3 μm, the adhesive layer is formed of a cured product layer of an active energy ray-curable resin composition, and the glass transition temperature of the cured product layer (hereinafter, also referred to as “Tg” ) is less than 30°C.

In the optical layered body, the active energy ray-curable resin composition contains 20 to 90 parts by mass of a (meth)acrylate having a polar group when the total amount of the composition is 100 parts by mass. preferable.

In the above optical laminate, the polar group is preferably a hydroxyl group or a carboxyl group.

In the optical layered body, the active energy ray-curable resin composition contains 5 to 90 parts by mass of (meth)acrylate having an alkylene glycol unit when the total amount of the composition is 100 parts by mass. is preferred.

In the optical layered body, the active energy ray-curable resin composition preferably contains 3 to 20 parts by mass of a polyfunctional (meth)acrylate when the total amount of the composition is 100 parts by mass.

In the above optical layered body, the active energy ray-curable resin composition preferably contains 3 to 20 parts by mass of an acrylic oligomer when the total amount of the composition is 100 parts by mass.

In the optical layered body, the active energy ray-curable resin composition contains 30 polymer components having a glass transition temperature exceeding 30° C. when homopolymerized, when the total amount of the composition is 100 parts by mass. It is preferably not more than parts by mass.

In the above optical layered body, it is preferable that the optical function layer is a liquid crystal layer.

It is preferable that the above-described optical layered body includes a bending region that is bent along a bending axis located between two non-bending regions.

In the above optical layered body, it is preferable that the optical function layer is bent so as to be positioned on the outside.

The present invention also relates to an image display device using any one of the optical laminates described above.

The optical laminate according to the present invention is obtained by laminating an optical function layer and a base film via an adhesive layer, and the thickness of the optical function layer is as thin as 0.5 to 5 μm. For example, when the optical layered body having such a structure is bent so that the optical function layer is positioned on the outside, a strong stress is applied to the thin optical function layer in the extending direction. In this case, not only is it impossible to ensure the adhesion between the adhesive layer and the optical function layer, but cracks may occur in the optical function layer. However, in the optical laminate according to the present invention, the adhesive layer is formed of a cured product layer of the active energy ray-curable resin composition, and the glass transition temperature of the cured product layer is designed to be less than 30°C. It is Therefore, even if force is applied to bend the optical layered body, the soft adhesive layer relaxes the stress applied to the optical function layer. As a result, it is possible to improve the crack resistance of the optical functional layer while ensuring the adhesion between the optical functional layer and the adhesive layer.

In particular, the active energy ray-curable resin composition, which is a raw material for the adhesive layer, is a (meth)acrylate having a polar group, particularly a (meth)acrylate having a hydroxyl group or a carboxyl group, or a (meth)acrylate having an alkylene glycol unit. When a predetermined amount of acrylate, acrylic oligomer, or polyfunctional (meth)acrylate is contained, the adhesion between the optical function layer and the adhesive layer is excellent both in the normal state (when not folded) and when folded. In addition, due to the excellent adhesion between the optical function layer and the adhesive layer, the crack resistance of the optical function layer is further improved even if the optical function layer is folded.

As described above, the optical layered body according to the present invention has excellent adhesion of the adhesive layer and crack resistance of the thin optical function layer not only when it is normal (when not folded) but also when it is folded. can improve sexuality. To this end, in particular an optical stack comprising a folding region that is folded along a folding axis located between two non-folding regions, and an optical stack for an image display device in which the display screen can be curved, bent, folded or rolled up Useful as a body.

It is an example which shows the aspect which bent the optical laminated body which concerns on this invention. 1 is a schematic diagram of a 180° folding endurance tester (manufactured by Imoto Seisakusho Co., Ltd.); FIG.

The optical laminate according to the present invention is obtained by laminating an optical function layer and a base film via an adhesive layer. Each configuration will be described below.

(Optical function layer)
A thin film having a thickness of 0.5 to 5 μm is used as the optical function layer. From the viewpoint of thinning the optical layered body, the thickness of the optical function layer is more preferably 0.5 to 3 μm.

In the optical laminate according to the present invention, the adhesive layer is formed of a cured product layer of an active energy ray-curable resin composition, and the glass transition temperature of the cured product layer is designed to be less than 30°C. there is Therefore, when the optical function layer is brittle, specifically, even if the breaking stress is 5 N/10 mm or less, the crack resistance of the optical function layer can be improved, which is preferable.

In the present invention, the optical function layer is preferably a liquid crystal layer. The liquid crystal layer can be formed, for example, by applying a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound directly on the substrate film or on an alignment film, aligning the polymerizable liquid crystal compound, and polymerizing it. .

The liquid crystal layer contains at least a liquid crystal compound. The liquid crystal compound is preferably a polymerizable liquid crystal compound. That is, the liquid crystal layer preferably contains a cured polymerizable liquid crystal composition containing a polymerizable liquid crystal compound. In other words, the liquid crystal layer preferably has a fixed alignment state of the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is not particularly limited, and can be appropriately selected according to the desired retardation value, wavelength dispersion, orientation, solubility, and the like. In addition, the polymerizable liquid crystal compound may be used singly or in combination of two or more. By using two or more polymerizable liquid crystal compounds in combination, it is possible to adjust the retardation value, wavelength dispersion, orientation, solubility, phase transition temperature, and the like. In addition to the polymerizable compound, if necessary, a polymerizable liquid crystal composition containing a polymerizable compound having no liquid crystallinity, a photopolymerization initiator, a sensitizer, a leveling agent, an antioxidant, a light stabilizer, etc. You can use it as an object.

A polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group, and includes a monofunctional liquid crystal compound with one polymerizable group and a polyfunctional liquid crystal compound with two or more polymerizable groups. Among them, polyfunctional liquid crystal compounds are preferred, polyfunctional liquid crystal compounds having two or three polymerizable groups are more preferred, and polyfunctional liquid crystal compounds having two polymerizable groups are even more preferred. The polymerizable group can be polymerized by irradiation with an active energy ray such as ultraviolet rays, and examples thereof include ethylenically unsaturated double bonds such as vinyl groups, acryloyl groups, and methacryloyl groups. Moreover, the polymerizable liquid crystal compound may be a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound.

The liquid crystal phase of the polymerizable liquid crystal compound is not particularly limited, and may be, for example, nematic phase, smectic phase, cholesteric phase, or discotic phase. Further, the liquid crystal layer may be, for example, a polymerizable liquid crystal compound fixed in a state of exhibiting a nematic phase, or a polymerizable liquid crystal compound fixed in a state of exhibiting a cholesteric phase. Well, the polymerizable liquid crystal compound may be immobilized in a state showing a smectic phase.

The orientation state of the liquid crystal compound contained in the liquid crystal layer may be, for example, horizontal orientation, vertical orientation, tilt orientation, twist orientation, or hybrid orientation with respect to the surface of the base film.

(Base film)
The thickness of the base film is not particularly limited, but the thickness of the base film is 0.5 to 40 μm, especially considering the balance between the improvement of the crack resistance of the optical function layer and the thinning of the optical laminate. and more preferably 0.5 to 30 μm.

Since the optical functional layer included in the optical layered body according to the present invention is as thin as 0.5 to 5 μm in thickness, the breaking stress of the base film is 10 N/10 mm or more from the standpoint of improving the crack resistance of the optical functional layer. is preferable, and 20 N/10 mm or more is more preferable. In addition, when a base film is a stretched film, breaking stress means the breaking stress of MD direction. Moreover, the breaking stress of the base film is preferably 80 N/10 mm or less, more preferably 60 N/10 mm or less.

As the base film, any film having the above thickness and the above breaking stress can be used, but polyethylene terephthalate film (PET film) or triacetyl cellulose film (TAC film) is preferably used. It is possible.

In the present invention, instead of the base film, an optical laminate in which at least two optical functional layers are laminated via an adhesive layer may be used.

(adhesive layer)
The adhesive layer included in the optical laminate according to the present invention is formed of a cured product layer of an active energy ray-curable resin composition, and is characterized in that the cured product layer has a Tg of less than 30°C. The Tg of the cured product layer can be optimized by adjusting the blending ratio of the materials constituting the active energy ray-curable resin composition. From the viewpoint of improving both the adhesion between the optical film and the adhesive layer and the crack resistance of the optical film in a well-balanced manner, the Tg of the cured product layer is more preferably less than 30°C. Although the lower limit of Tg of the cured product layer is not particularly limited, it can be, for example, about -50°C. The thickness of the adhesive layer is 0.5 to 3 μm, more preferably 0.5 to 2.5 μm.

In addition, from the viewpoint of improving both the adhesion between the optical film and the adhesive layer and the crack resistance of the optical film in a well-balanced manner, the storage elastic modulus E′ of the cured product layer of the active energy ray-curable resin composition (Pa (25° C.)) is preferably 1×10 ⁴ to 5×10 ⁷ , more preferably 1×10 ⁵ to 1×10 ⁷ . Materials constituting the active energy ray-curable resin composition are described below.

Active energy ray-curable resin compositions can be classified into radically polymerizable and cationic polymerizable resin compositions. In the present invention, active energy rays with a wavelength range of 10 nm to less than 380 nm are expressed as ultraviolet rays, and active energy rays with a wavelength range of 380 nm to 800 nm are expressed as visible rays.

Examples of monomer components constituting the radically polymerizable curable resin composition include compounds having radically polymerizable functional groups of carbon-carbon double bonds such as (meth)acryloyl groups and vinyl groups. These monomer components can be either monofunctional radically polymerizable compounds or multifunctional radically polymerizable compounds having two or more polymerizable functional groups. Moreover, these radical polymerizable compounds can be used individually by 1 type or in combination of 2 or more types. As these radically polymerizable compounds, for example, (meth)acrylates having a (meth)acryloyl group are suitable. In the present invention, (meth)acryloyl means an acryloyl group and/or a methacryloyl group, and "(meth)" has the same meaning below.

In the present invention, when a (meth)acrylate having a polar group is used as the monofunctional radically polymerizable compound, the adhesion between the optical film and the adhesive layer is improved even in a humidified environment, especially when the adhesive layer is folded. is excellent and the crack resistance of the optical film can be improved. Among the polar groups, a hydroxyl group or a carboxyl group is particularly preferred.

Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl Hydroxyalkyl (meth)acrylates such as (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone, 1,4-cyclohexane and dimethanol monoacrylate.

Further, as the hydroxyl group-containing (meth)acrylate, when a (meth)acrylate having an alkylene glycol unit and a terminal hydroxyl group is used, the Tg of the resulting adhesive layer (cured material layer) is lowered while optical It is preferable because it can improve the adhesion between the film and the adhesive layer. Examples of the (meth)acrylate having an alkylene glycol unit and a terminal hydroxyl group include polyethylene glycol (meth)acrylate having an average of 2 to 10 ethylene glycol units, and an average of 2 to 13 propylene glycol units. and polypropylene glycol (meth)acrylate having

Examples of hydroxyl group-containing (meth)acrylates include N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-methylol-N-propane (meth)acrylamide. Available.

Carboxyl group-containing (meth)acrylates include (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

In the present invention, the active energy ray-curable resin composition preferably contains 20 to 90 parts by mass of a (meth)acrylate having a polar group when the total amount of the composition is 100 parts by mass. It is more preferable to contain 30 to 80 parts by mass.

In addition, the (meth)acrylate having a polar group preferably has a glass transition temperature of 30° C. or less when homopolymerized, and 0° C. or less, from the viewpoint of lowering the Tg of the resulting adhesive layer (cured material layer). is more preferred.

In the present invention, when a (meth)acrylate having an alkylene glycol unit is used as the monofunctional radically polymerizable compound, adhesion between the optical film and the adhesive layer is maintained even in a humidified environment, especially when the adhesive layer is folded. It is preferable because it has excellent properties and can improve the crack resistance of the optical film. The (meth)acrylate having an alkylene glycol unit may be a (meth)acrylate having the alkylene glycol unit described above and having a hydroxyl group at the end, or a methyl group, an ethyl group, and 2-ethylhexyl at the end. and alkoxy groups such as methoxy, ethoxy, and phenoxy groups.

In the present invention, the active energy ray-curable resin composition preferably contains 5 to 90 parts by mass of (meth)acrylate having an alkylene glycol unit when the total amount of the composition is 100 parts by mass. , more preferably 15 to 80 parts by mass.

In the present invention, as the monofunctional radically polymerizable compound, a compound other than (meth)acrylate having a polar group and (meth)acrylate having an alkylene glycol unit may be used. Usable (meth)acrylates include, for example, (meth)acrylamide derivatives having a (meth)acrylamide group. A (meth)acrylamide derivative is preferable in terms of securing adhesion to the optical function layer and/or the substrate film, and in terms of high polymerization rate and excellent productivity. Specific examples of (meth)acrylamide derivatives include N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N -N-alkyl group-containing (meth)acrylamide derivatives such as butyl (meth)acrylamide and N-hexyl (meth)acrylamide;; N-aminoalkyl group-containing (such as aminomethyl (meth)acrylamide and aminoethyl (meth)acrylamide) meth)acrylamide derivatives; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; N-mercaptoalkyl group-containing derivatives such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide (meth)acrylamide derivatives; and the like. Further, the heterocycle-containing (meth)acrylamide derivative in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle includes, for example, N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine etc.

In addition, examples of monofunctional radically polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, 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 ( Examples include (meth)acrylic acid (C1-20) alkyl esters such as meth)acrylate and n-octadecyl (meth)acrylate.

Examples of the (meth)acrylic acid derivative include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, dicyclopentenyl (meth) ) Polycyclic (meth)acrylates such as acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxy Ethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, alkylphenoxy polyethylene glycol (meth) acrylate, etc. alkoxy group- or phenoxy group-containing (meth)acrylates; and the like.

In the present invention, a compound represented by the following formula (1) as a monofunctional radically polymerizable compound;

(where X is a functional group containing a reactive group, R ¹ and R ² are each independently a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group, or a heterocyclic group represents), preferably a compound according to the general formula (1′);

(where Y is an organic group, X' is a reactive group contained in X, and R ¹ and R ² are the same as described above), more preferably the following general formulas (1a) to (1d) Compound;

can be blended into the active energy ray-curable resin composition. When these compounds are blended in the active energy ray-curable resin composition, the adhesion between the optical function layer and the substrate film may be improved, which is preferable. From the standpoint of improving the adhesion between the optical functional layer and the substrate film, the content of the compound represented by the general formula (1) in the active energy ray-curable resin composition is 0.1 to 10 parts by mass. is preferred, and 0.5 to 5 parts by mass is more preferred.

In the general formula (1), the aliphatic hydrocarbon group includes a linear or branched alkyl group optionally having a substituent having 1 to 20 carbon atoms, and a substituent having 3 to 20 carbon atoms. cyclic alkyl groups which may be substituted, and alkenyl groups having 2 to 20 carbon atoms. optionally substituted naphthyl groups and the like, and examples of heterocyclic groups include 5- or 6-membered ring groups containing at least one heteroatom and optionally having substituents. These may be linked together to form a ring. In formula (1), R ¹ and R ² are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, most preferably a hydrogen atom.

X possessed by the compound represented by the general formula (1) is a functional group containing a reactive group, and the reactive group contained in X includes, for example, a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, and a vinyl group. , (meth)acryl group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, α,β-unsaturated carbonyl group, mercapto group, halogen group and the like. The reactive group contained in X is at least one reactive group selected from the group consisting of a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group and a mercapto group. is preferably a group, and particularly when the active energy ray-curable resin composition is radically polymerizable, the reactive group contained in X is selected from the group consisting of a (meth)acryl group, a styryl group and a (meth)acrylamide group. It is preferably at least one selected reactive group, and when the compound represented by the general formula (1) has a (meth)acrylamide group, the reactivity is high, and the active energy ray-curable resin composition and It is more preferable because the copolymerization rate of is increased. In addition, the (meth)acrylamide group has a high polarity and is excellent in adhesiveness, so it is preferable from the viewpoint that the effects of the present invention can be obtained efficiently. When the curable resin composition that constitutes the adhesive layer is cationic polymerizable, the reactive group contained in X is a hydroxyl group, an amino group, an aldehyde, a carboxyl group, a vinyl ether group, an epoxy group, an oxetane group, or a mercapto group. It is preferable to have at least one selected functional group, especially when it has an epoxy group, it is preferable for excellent adhesion between the resulting curable resin layer and the adherend, and when it has a vinyl ether group, the curable resin composition is preferred because of its excellent curability.

In the present invention, the compound represented by the general formula (1) may be one in which the reactive group and the boron atom are directly bonded. The compound represented by is preferably one in which a reactive group and a boron atom are bonded via an organic group, that is, a compound represented by general formula (1′). For example, when the compound represented by the general formula (1) is bonded to a reactive group via an oxygen atom bonded to a boron atom, the adhesion water resistance of the polarizing film tends to deteriorate. On the other hand, the compound represented by the general formula (1) does not have a boron-oxygen bond, but has a boron-carbon bond by bonding a boron atom and an organic group, and contains a reactive group. When it is a compound (when represented by general formula (1′)), it is preferable because the adhesive water resistance of the polarizing film is improved. The organic group specifically means an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically, for example, having a substituent having 1 to 20 carbon atoms. A linear or branched alkylene group which may be optionally substituted, a cyclic alkylene group which may have a substituent of 3 to 20 carbon atoms, a phenylene group which may have a substituent of 6 to 20 carbon atoms, a phenylene group which may have a substituent of 10 to 10 carbon atoms. A naphthylene group which may have 20 substituents may be mentioned.

As the compound represented by the general formula (1), in addition to the compounds exemplified above, esters of hydroxyethylacrylamide and boric acid, esters of methylolacrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and hydroxybutyl Esters of (meth)acrylates and boric acid can be exemplified, such as esters of acrylate and boric acid.

In the present invention, when the active energy ray-curable resin composition contains a polyfunctional (meth)acrylate as a polyfunctional radically polymerizable compound, the optical film and the adhesive can be used in a humidified environment, especially even when the adhesive is folded. It is preferable because it has excellent adhesion between the layers and can improve the crack resistance of the optical film. Examples of polyfunctional (meth)acrylates include tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, 1,6-hexanediol di (Meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, Esterified products of (meth)acrylic acid and polyhydric alcohols, such as dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated glycerin triacrylate, and EO-modified diglycerin tetra(meth)acrylate, 9 ,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include light acrylate 9EG-A (manufactured by Kyoeisha Chemical Co., Ltd.), Blemmer ADP-400 (manufactured by NOF Corporation), NK ester A-GLY-9E (manufactured by Shin-Nakamura Chemical Co., Ltd.), light acrylate 1,9ND- A (manufactured by Kyoeisha Chemical Co., Ltd.), Aronix M-220 (manufactured by Toagosei Co., Ltd.), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer ), CD-536 (manufactured by Sartomer), and the like. Various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, various (meth)acrylate monomers, and the like can also be used as necessary.

In the present invention, the active energy ray-curable resin composition preferably contains 3 to 20 parts by mass of a polyfunctional (meth)acrylate when the total amount of the composition is 100 parts by mass. It is more preferable to contain 15 parts by mass.

The adhesive layer included in the optical laminate according to the present invention is formed of a cured product layer of an active energy ray-curable resin composition, and is characterized in that the cured product layer has a Tg of less than 30°C. However, from the viewpoint of improving both the adhesion between the optical film and the adhesive layer and the crack resistance of the optical film in a well-balanced manner, when the total amount of the composition is 100 parts by mass, the glass when homopolymerized The content of the polymerized component having a transition temperature exceeding 30°C is preferably 30 parts by mass or less, and the content of the polymerized component having a glass transition temperature exceeding 30°C when homopolymerized is 20 parts by mass or less. It is more preferable to be

In the present invention, the active energy ray-curable resin composition preferably contains an acrylic oligomer obtained by polymerizing a (meth)acrylic monomer. By containing an acrylic oligomer in the active energy ray-curable resin composition, curing shrinkage when irradiating and curing the composition with an active energy ray is reduced, and the adhesive layer, the optical function layer and the base material Interfacial stress with an adherend such as a film can be reduced. As a result, deterioration in adhesion between the adhesive layer and the adherend can be suppressed.

Considering workability and uniformity during coating, the active energy ray-curable resin composition preferably has a low viscosity. Preferably. The acrylic oligomer which has a low viscosity and can prevent curing shrinkage of the adhesive layer preferably has a weight-average molecular weight (Mw) of 15,000 or less, more preferably 10,000 or less, and particularly 5,000 or less. preferable. On the other hand, in order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more. 1500 or more is particularly preferable. Specific examples of the (meth)acrylic monomer constituting the acrylic oligomer include 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)acrylic acid (C1-20) alkyl esters such as meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate, and further, for example, cycloalkyl (meth) ) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, etc.), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) ) acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, etc.), hydroxyl group-containing (meth) ) Acrylic esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth)acryl Acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxy ethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (e.g., 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) ) acrylate, etc.), alkylaminoalkyl (meth)acrylate (eg, dimethylaminoethyl (meth)acrylate, etc.), and the like. These (meth)acrylates can be used alone or in combination of two or more. Specific examples of the acrylic oligomer (E) include "ARUFON" manufactured by Toagosei Co., Ltd., "ACT FLOW" manufactured by Soken Chemical Co., Ltd., and "JONCRYL" manufactured by BASF Japan.

In the optical layered body, the active energy ray-curable resin composition preferably contains 3 to 20 parts by mass, more preferably 3 to 15 parts by mass, of the acrylic oligomer when the total amount of the composition is 100 parts by mass. It is more preferable to contain a part.

The active energy ray-curable resin composition used in the present invention preferably contains a photopolymerization initiator. A photopolymerization initiator is appropriately selected depending on the active energy ray. When curing with ultraviolet light or visible light, a photopolymerization initiator that is cleaved with ultraviolet light or visible light is used. Examples of the photopolymerization initiator include benzophenone compounds such as benzyl, benzophenone, benzoylbenzoic acid, and 3,3′-dimethyl-4-methoxybenzophenone; 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2 -propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α-hydroxycyclohexylphenylketone and other aromatic ketone compounds; methoxyacetophenone, 2,2-dimethoxy- Acetophenone compounds such as 2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin methyl ether, Benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4- Thioxanthone compounds such as dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone; camphorquinone; halogenated ketone; acylphosphinoxide; acylphosphonate, and the like.

The amount of the photopolymerization initiator is preferably 0.5 to 5 parts by mass, preferably 1 to 4 parts by mass, when the total amount of the active energy ray-curable resin composition is 100 parts by mass. It is more preferable that

In addition, when using a visible light-curable active energy ray-curable resin composition, it is preferable to use a photopolymerization initiator that is particularly sensitive to light of 380 nm or more. A photopolymerization initiator highly sensitive to light of 380 nm or more will be described later.

As the photopolymerization initiator, a compound represented by the following general formula (2);

(wherein R ³ and R ⁴ represent —H, —CH ₂ CH ₃ , —iPr or Cl, and R ³ and R ⁴ may be the same or different), or the general formula ( It is preferable to use the compound represented by 1) together with a photopolymerization initiator highly sensitive to light of 380 nm or longer, which will be described later. When the compound represented by the general formula (2) is used, the adhesiveness is superior to the case where a photopolymerization initiator highly sensitive to light of 380 nm or more is used alone. Among the compounds represented by general formula (2), diethylthioxanthone in which R ¹ and R ² are —CH ₂ CH ₃ is particularly preferred. The amount of the compound represented by the general formula (2) in the active energy ray-curable resin composition is 0.1 to 4 parts by mass when the total amount of the active energy ray-curable resin composition is 100 parts by mass. It preferably contains 0.5 to 3 parts by mass, more preferably 0.5 to 3 parts by mass.

In addition, it is preferable to add a polymerization initiation aid as necessary. Examples of polymerization initiation aids include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate. and ethyl 4-dimethylaminobenzoate is particularly preferred. When a polymerization initiation aid is used, the amount added is preferably 0.1 to 3 parts by mass when the total amount of the active energy ray-curable resin composition is 100 parts by mass. It is more preferable to contain 3 to 1 part by mass.

In addition, a known photopolymerization initiator can be used together as needed. Since the optical functional layer and base film having UV absorbability do not transmit light of 380 nm or less, it is preferable to use a photopolymerization initiator highly sensitive to light of 380 nm or more as the photopolymerization initiator. . Specifically, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 , 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole- 1-yl)-phenyl) titanium and the like.

The active energy ray-curable resin composition used in the present invention preferably contains a silane coupling agent. Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycide as active energy ray-curable compounds. xypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane silane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and the like.

　Preferred are 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

The amount of the silane coupling agent compounded is preferably in the range of 0.01 to 20% by mass, preferably 0.05 to 15% by mass, based on the total amount of the active energy ray-curable resin composition. It is more preferably 1 to 10% by mass. This is because if the amount exceeds 20% by mass, the storage stability of the active energy ray-curable resin composition deteriorates, and if the amount is less than 0.1% by mass, the effect of adhesion water resistance is not sufficiently exhibited.

Specific examples of non-active energy ray-curable silane coupling agents other than the above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. silane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazolesilane, and the like.

The active energy ray-curable resin composition used in the present invention may be a cationic polymerization-curable resin composition. The cationically polymerizable compound used in the cationically polymerizable curable resin composition includes a monofunctional cationically polymerizable compound having one cationically polymerizable functional group in the molecule and two or more cationically polymerizable functional groups in the molecule. It is classified into polyfunctional cationic polymerizable compounds with Since the monofunctional cationically polymerizable compound has a relatively low liquid viscosity, the liquid viscosity can be reduced by including it in the cationically polymerizable curable resin composition. In addition, the monofunctional cationically polymerizable compound often has a functional group that exhibits various functions. Various functions can be expressed in the cured product of the curable resin composition. Since the polyfunctional cationically polymerizable compound can three-dimensionally crosslink the cured product of the cationically polymerizable curable resin composition, it is preferably contained in the cationically polymerizable curable resin composition. The ratio of the monofunctional cationically polymerizable compound and the polyfunctional cationically polymerizable compound is to mix 10 parts by mass to 1000 parts by mass of the polyfunctional cationically polymerizable compound with respect to 100 parts by mass of the monofunctional cationically polymerizable compound. is preferred. Examples of cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Compounds having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. It is particularly preferred to contain a cyclic epoxy compound. Alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, caprolactone-modified products of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and trimethylcaprolactone-modified products. and valerolactone modified products, and specifically, Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2083, Celoxide 2085 (manufactured by Daicel Chemical Industries, Ltd., Cyracure UVR-6105, Cyracure UVR -6107, Cyracure 30, R-6110 (manufactured by Dow Chemical Japan Co., Ltd.), etc. Compounds having an oxetanyl group improve the curability of the cationic polymerizable resin composition, The compound having an oxetanyl group includes 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, phenol novolak Oxetane and the like are mentioned, and Aron oxetane OXT-101, Aron oxetane OXT-121, Aron oxetane OXT-211, Aron oxetane OXT-221, Aron oxetane OXT-212 (manufactured by Toagosei Co., Ltd.) and the like are commercially available. A compound having a vinyl ether group has the effect of improving the curability of the cationic polymerizable resin composition and lowering the liquid viscosity of the composition, so it is preferable to include the compound having a vinyl ether group. -hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxy Examples include ethyl vinyl ether and pentaerythritol type tetravinyl ether.

The cationically polymerizable curable resin composition contains at least one compound selected from the epoxy group-containing compound, the oxetanyl group-containing compound, and the vinyl ether group-containing compound described above as a curable component. A photo cationic polymerization initiator is blended because it is cured by This cationic photopolymerization initiator generates cationic species or Lewis acid upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays and electron beams, and initiates the polymerization reaction of epoxy groups and oxetanyl groups. As the photocationic polymerization initiator, a photoacid generator described later is preferably used. In addition, when the cationic polymerizable resin composition is used with visible light curing, it is preferable to use a cationic photopolymerization initiator that is highly sensitive to light of 380 nm or more. Since it is a compound that exhibits maximum absorption in a wavelength region near or shorter than that, by blending a photosensitizer that exhibits maximum absorption in a wavelength region longer than that, specifically, light with a wavelength longer than 380 nm, and can promote the generation of cationic species or acid from the photocationic polymerization initiator. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducible dyes, and the like. You may use it in mixture of 2 or more types. Anthracene compounds are particularly preferable because of their excellent photosensitizing effect, and specific examples thereof include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Kasei Co., Ltd.). The content of the photosensitizer is preferably 0.1% by mass to 5% by mass, more preferably 0.5% by mass to 3% by mass.

In the present invention, the active energy ray-curable resin composition may contain a photoacid generator. When the active energy ray-curable resin composition contains a photoacid generator, the water resistance and durability of the adhesive layer can be dramatically improved as compared with the case where the photoacid generator is not contained. The photoacid generator can be represented by the following general formula (3).

General formula (3)

(wherein L ⁺ represents any onium cation, and X ⁻ is PF6 ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ − , SbCl ₆ ⁻ , BiCl ₅ ⁻ , SnCl ₆ ⁻ ^, ClO ₄ ⁻ , dithiocarbamate represents a counter anion selected from the group consisting of an anion and SCN-.)

Next, the counter anion X ⁻ in general formula (3) will be explained.

The counter anion X 1 ⁻ in general formula (3) is not particularly limited in principle, but is preferably a non-nucleophilic anion. When the counter anion X ⁻ is a non-nucleophilic anion, nucleophilic reactions in cations coexisting in the molecule and various materials used in combination are unlikely to occur, and as a result, the photoacid generator represented by general formula (4) itself It is possible to improve the aging stability of the composition using it. A non-nucleophilic anion as used herein refers to an anion having a low ability to cause a nucleophilic reaction. Such anions include PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , SbCl ₆ ⁻ , BiCl ₅ ⁻ , SnCl ₆ ⁻ , ClO ₄ ⁻ , B(C ₆ H ₅ ) ₄ ⁻ , dithiocarbamate anion, SCN ^- and the like.

Specifically, "Cyracure UVI-6992", "Cyracure UVI-6974" (manufactured by Dow Chemical Japan Co., Ltd.), "ADEKA OPTOMER SP150", "ADEKA OPTOMER SP152", "ADEKA OPTOMER SP170", "Adeka Optomer SP172" (manufactured by ADEKA Corporation), "Omnicat250" (manufactured by IGM Resins B.V.), "CI-5102", "CI-2855" (manufactured by Nippon Soda Co., Ltd.) ), “San-Aid SI-60L”, “San-Aid SI-80L”, “San-Aid SI-100L”, “San-Aid SI-110L”, “San-Aid SI-180L” (manufactured by Sanshin Chemical Co., Ltd.), “IK-1 ”, “CPI-100P”, “CPI-101A”, “CPI-110P”, “CPI-200K”, “CPI-210S”, “CPI-310B”, “CPI-410B”, “CPI-410S” ( Above, manufactured by San-Apro Co., Ltd.), “WPI-069”, “WPI-113”, “WPI-116”, “WPI-041”, “WPI-044”, “WPI-054”, “WPI-055”, "WPAG-281", "WPAG-567" and "WPAG-596" (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) are preferred specific examples of the photoacid generator of the present invention.

The content of the photoacid generator in the active energy ray-curable resin composition is 0.1 to 5 parts by mass when the total amount of the active energy ray curable resin composition is 100 parts by mass. is preferred, and 0.5 to 4 parts by mass is more preferred.

The optical layered body according to the present invention can be produced, for example, by the following production method.
A method for producing an optical laminate in which an optical functional layer and a substrate film are laminated via an adhesive layer, wherein the active energy ray described above is applied to at least one surface of the optical functional layer and the substrate film. A coating step of applying a curable resin composition, a bonding step of bonding the optical function layer and the base film, and irradiating an active energy ray from the optical function layer surface side or the base film surface side. and a bonding step of bonding the optical function layer and the base film via an adhesive layer obtained by curing the active energy ray-curable resin composition.

The optical functional layer and base film may be subjected to surface modification treatment before the coating process. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment and flame treatment, with corona treatment being particularly preferred. By performing the corona treatment, reactive functional groups such as carbonyl groups and amino groups are generated on the surface of the optical function layer and/or the substrate film, thereby improving adhesion to the adhesive layer. In addition, foreign matter on the surface is removed by the ashing effect, and unevenness on the surface is reduced, so that an optical layered body with excellent appearance characteristics can be produced.

<Coating process>
The method of applying the active energy ray-curable resin composition is appropriately selected depending on the viscosity of the composition and the desired thickness. A coater, a die coater, a bar coater, a rod coater and the like can be mentioned. The viscosity of the active energy ray-curable resin composition used in the present invention is preferably 3 to 100 mPa·s, more preferably 5 to 50 mPa·s, and most preferably 10 to 30 mPa·s. When the viscosity of the composition is high, the surface smoothness after coating is poor, resulting in poor appearance, which is not preferable. The active energy ray-curable resin composition used in the present invention can be applied by heating or cooling the composition to adjust the viscosity to a preferred range.

<Lamination process>
The optical functional layer and the substrate film are bonded together via the active energy ray-curable resin composition coated as described above. The optical function layer and the substrate film can be attached together using a roll laminator or the like.

<Adhesion process>
After bonding the optical function layer and the substrate film together, an active energy ray (electron beam, ultraviolet rays, visible light, etc.) is irradiated to cure the active energy ray-curable resin composition to form an adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet rays, visible rays, etc.) can be any suitable direction.

Any appropriate irradiation conditions can be adopted as long as the irradiation conditions for electron beam irradiation are such that the active energy ray-curable resin composition can be cured. For example, electron beam irradiation preferably has an acceleration voltage of 5 kV to 300 kV, more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive, resulting in insufficient curing. It may cause damage. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the adhesive will be insufficiently cured, and if it exceeds 100 kGy, the optical function layer and the base film will be damaged, the mechanical strength will be reduced, yellowing will occur, and the desired optical properties will be obtained. I can't.

　Electron beam irradiation is usually carried out in an inert gas, but if necessary, it may be carried out in the air or with a small amount of oxygen introduced. Although it depends on the materials of the optical functional layer and the substrate film, by appropriately introducing oxygen, the surfaces of the optical functional layer and the substrate film that are first exposed to the electron beam are intentionally inhibited by oxygen, and the optical functional layer and the substrate film are exposed. can be prevented, and only the adhesive can be efficiently irradiated with the electron beam.

When producing the optical layered product according to the present invention, active energy rays containing visible light with a wavelength range of 380 nm to 450 nm, particularly active energy rays with the largest irradiation amount of visible light with a wavelength range of 380 nm to 450 nm are used. preferably. When using ultraviolet light or visible light, and when using an optical functional layer or substrate film imparted with ultraviolet absorption ability (ultraviolet non-transmissive optical functional layer or substrate film), light with a wavelength shorter than approximately 380 nm , light with a wavelength shorter than 380 nm does not reach the active energy ray-curable resin composition and does not contribute to its polymerization reaction. Furthermore, light with a wavelength shorter than 380 nm absorbed by the optical functional layer or substrate film is converted into heat, and the optical functional layer or substrate film itself generates heat, which causes defects such as curling and wrinkling of the optical laminate. . Therefore, when ultraviolet light and visible light are used in the present invention, it is preferable to use a device that does not emit light with a wavelength shorter than 380 nm as an active energy ray generator, more specifically, an integrated wavelength range of 380 to 440 nm. The ratio of the illuminance to the integrated illuminance in the wavelength range of 250 to 370 nm is preferably 100:0 to 100:50, more preferably 100:0 to 100:40. When producing the optical laminate according to the present invention, the active energy ray is preferably a gallium-encapsulated metal halide lamp or an LED light source emitting light in a wavelength range of 380 to 440 nm. Alternatively, ultraviolet rays from low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, extra high pressure mercury lamps, incandescent lamps, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, excimer lasers, or sunlight. A light source containing visible light can be used, and a band-pass filter can be used to cut off ultraviolet light with a wavelength shorter than 380 nm. In order to prevent curling of the optical laminate while improving the adhesive performance of the adhesive layer between the optical functional layer and the base film, a gallium-filled metal halide lamp is used and light with a wavelength shorter than 380 nm is blocked. It is preferable to use an active energy ray obtained through a possible bandpass filter or an active energy ray with a wavelength of 405 nm obtained using an LED light source.

It is preferable to heat the active energy ray-curable resin composition before irradiation with ultraviolet light or visible light (pre-irradiation heating), in which case the temperature is preferably 40°C or higher, and the temperature is preferably 50°C or higher. is more preferable. It is also preferable to heat the active energy ray-curable resin composition after irradiation with ultraviolet light or visible light (post-irradiation heating). is more preferable.

When the optical laminate according to the present invention is produced in a continuous line, the line speed is preferably 1 to 500 m/min, more preferably 5 to 300 m/min, although it depends on the curing time of the active energy ray-curable resin composition. More preferably, it is 10 to 100 m/min. If the line speed is too low, the productivity will be poor, or the damage to the optical functional layer or substrate film will be too great, and an optical laminate that can withstand durability tests and the like cannot be produced. If the line speed is too high, the curing of the active energy ray-curable resin composition may be insufficient and the intended adhesiveness may not be obtained.

In the method for producing an optical layered body according to the present invention, an easy-adhesion layer containing a specific boric acid group-containing compound is formed on the bonding surface of at least one of the optical function layer and the substrate film before the coating step. An easy-adhesion treatment process may be provided. Specifically, the following manufacturing method;
A method for producing an optical laminate in which an optical functional layer and a substrate film are laminated via an adhesive layer, wherein the compound represented by the general formula (1) is applied to the bonding surface of at least one of the optical functional layer and the substrate film. A compound represented by, more preferably a compound represented by general formula (1′) is adhered to an easy-adhesion treatment step, and at least one bonding surface of the optical function layer and the base film is coated with an active energy ray-curable A coating step of applying a resin composition, a lamination step of laminating an optical function layer and a substrate film, and irradiating an active energy ray from the optical function layer side or the substrate film side to cure the active energy ray. an optical layered body manufacturing method including an adhesion step of bonding the optical functional layer and the substrate film via an adhesive layer obtained by curing a flexible resin composition.

<Easy adhesion treatment process>
As a method of forming an easy-adhesion layer on at least one of the bonding surface of the optical function layer and the base film using the easy-adhesion composition containing the compound represented by general formula (1), for example, general formula (1 ) is prepared, and the composition is coated on at least one bonding surface of the optical function layer and the base film. In addition to the compound represented by formula (1), the easy-adhesion composition (A) may include solvents and additives.

When the easily adhesive composition (A) contains a solvent, the composition (A) is applied to the bonding surface of at least one of the optical function layer and the base film, and if necessary, a drying step or a curing treatment (such as heat treatment) is performed. ) may be performed.

As the solvent that the easy-adhesion composition (A) may contain, a solvent capable of stabilizing and dissolving or dispersing the compound represented by general formula (1) is preferable. An organic solvent, water, or a mixed solvent thereof can be used as such a solvent. Examples of the solvent include esters such as ethyl acetate, butyl acetate, and 2-hydroxyethyl acetate; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl-n-propyl ketone, and acetylacetone; tetrahydrofuran ( Cyclic ethers such as THF) and dioxane; Aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; Aromatic hydrocarbons such as toluene and xylene; Methanol, ethanol, n-propanol, isopropanol, cyclohexanol aliphatic or alicyclic alcohols such as; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and diethylene glycol monoethyl ether; glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; is selected from

Additives that the easy-adhesion composition (A) may contain include, for example, surfactants, plasticizers, tackifiers, low-molecular-weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, and corrosion inhibitors. agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, titanium coupling agents, inorganic or organic fillers, metal powders, particles, and foils.

If the content of the compound represented by general formula (1) in the easy-adhesion layer is too low, the proportion of the compound represented by general formula (1) present on the surface of the easy-adhesion layer decreases, resulting in poor adhesion. may be lower. Therefore, the content of the compound represented by general formula (1) in the easy-adhesion layer is preferably 1% by mass or more, more preferably 20% by mass or more, and 40% by mass or more. is more preferred.

Regarding the method of forming an easy-adhesion layer on the optical functional layer and/or the base film using the easy-adhesion composition (A), the lamination surface of at least one of the optical function layer and/or the base film is composed A method of direct immersion in the treatment bath for the product (A) or a known coating method can be used as appropriate. Specific examples of the coating method include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, and curtain coating, but are not limited to these.

In the present invention, if the easy-adhesion layer provided on the lamination surface of at least one of the optical function layer and/or the base film is too thick, the cohesive force of the easy-adhesion layer may be reduced, and the easy-adhesion effect may be reduced. be. Therefore, the thickness of the easy-adhesion layer is preferably 2000 nm or less, more preferably 1000 nm or less, and even more preferably 500 nm or less. On the other hand, the minimum thickness for the easy-adhesion layer to fully exhibit its effect includes at least the thickness of the monomolecular film of the compound represented by the general formula (1), preferably 1 nm or more, and more It is preferably 2 nm or more, more preferably 3 nm or more.

<Optical film>
The optical laminate of the present invention can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited. Examples thereof include optical layers, such as polarizing films, which are sometimes used in the formation of liquid crystal display devices and the like.

As the retardation film, a film having a front retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The front retardation is usually controlled in the range of 40-200 nm, and the thickness direction retardation is usually controlled in the range of 80-300 nm.

Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, and a film in which an oriented layer of a liquid crystal polymer is supported. Although the thickness of the retardation film is not particularly limited, it is generally about 20 to 150 μm.

As the retardation film, the following formulas (1) to (3):
0.70<Re[450]/Re[550]<0.97 (1)
1.5×10 ⁻³ <Δn<6×10 ⁻³ (2)
1.13<NZ<1.50 (3)
(Wherein, Re [450] and Re [550] are the in-plane retardation values of the retardation film measured with light having wavelengths of 450 nm and 550 nm, respectively, at 23 ° C., and Δn is the slow phase of the retardation film In-plane birefringence that is nx-ny when the refractive indices in the axial direction and the fast axis direction are nx and ny, respectively, and NZ is the refractive index in the thickness direction of the retardation film, (ratio of nx-nz, which is birefringence in the thickness direction, to nx-ny, which is in-plane birefringence) may be used.

An adhesive layer for adhering to other members such as liquid crystal cells can also be provided in the optical layered body described above and the optical film in which an optical layer is further layered on the optical layered body. The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based polymer, rubber-based polymer, or the like is appropriately selected. can be used as In particular, adhesives such as acrylic pressure-sensitive adhesives which are excellent in optical transparency, exhibit appropriate wettability, cohesiveness and adhesive properties, and are excellent in weather resistance and heat resistance can be preferably used.

The adhesive layer can also be provided on one side or both sides of the optical laminate as a superimposed layer of different compositions or types. Further, when provided on both sides, adhesive layers with different compositions, types, thicknesses, etc. can be provided on the front and back sides of the optical layered body. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 1 to 200 μm, particularly preferably 1 to 100 μm.

The exposed surface of the adhesive layer is temporarily covered with a separator for the purpose of preventing contamination until it is put into practical use. This prevents contact with the adhesive layer during normal handling conditions. As the separator, excluding the above thickness conditions, suitable thin sheets such as plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, foam sheets, metal foils, and laminates thereof may be used. An appropriate release agent according to the prior art, such as one coated with an appropriate release agent such as chain alkyl, fluorine, or molybdenum sulfide, can be used.

The optical layered body according to the present invention exhibits excellent adhesion of the adhesive layer and excellent crack resistance of the thin optical function layer not only in the normal state (when not folded) but also in the case of folding. . FIG. 1 is an example showing an aspect in which the optical laminate according to the present invention is folded. 20 is an example showing an aspect folded along 20. FIG. In FIG. 1, 11 indicates a bending area and 12 indicates a non-bending area. The optical function layer 1 included in the optical laminate A has a thin thickness of 0.5 to 5 μm. As shown in FIG. 1, when the optical layered body A having such a structure is bent so that the optical function layer 1 is positioned on the outside, a strong stress is applied to the thin optical function layer 1 in the direction of elongation. However, in the optical laminate A, the adhesive layer 2 is formed of a cured product layer of the active energy ray-curable resin composition, and the glass transition temperature of the cured product layer is designed to be less than 30°C. there is Therefore, even if a force is applied so as to bend the optical layered body A, the soft adhesive layer 2 relaxes the stress applied to the optical function layer 1 in the outward extending direction. As a result, the crack resistance of the optical functional layer 1 can be improved while ensuring the adhesion between the optical functional layer 1 and the adhesive layer 2 in particular.

<Image display device>
The optical laminate of the present invention can be preferably used for forming various devices such as liquid crystal display devices. Formation of the liquid crystal display device can be carried out according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or an optical film, and, if necessary, an illumination system, and incorporating a driving circuit. There is no particular limitation except that the polarizing film or optical film according to the invention is used, and conventional methods can be applied. As for the liquid crystal cell, any type such as TN type, STN type, or π type can be used.

Appropriate liquid crystal display devices can be formed, such as a liquid crystal display device in which an optical laminate is arranged on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector for an illumination system. In that case, the optical laminate according to the present invention can be placed on one side or both sides of the liquid crystal cell. If optical stacks are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, appropriate parts such as a diffuser plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffuser plate, and a backlight are arranged in a single layer or at an appropriate position. Two or more layers can be arranged.

The optical layered body according to the present invention has excellent adhesion between the optical film and the adhesive layer even in a humidified environment, especially when folded, and adhesion that can improve the crack resistance of the optical film. It has an agent layer. Therefore, it is particularly preferable for an image display device whose display screen can be curved, bent, folded or rolled up.

Examples of the present invention are described below, but embodiments of the present invention are not limited to these.

<Optical function layer>
A 4 μm-thick cholesteric liquid crystal layer (manufactured by Dai Nippon Printing Co., Ltd.) was used as the optical function layer. The breaking stress of the cholesteric liquid crystal layer used was 3 N/10 mm.

<Base film>
A polyethylene terephthalate (PET) film with a thickness of 25 μm (manufactured by Toyobo Co., Ltd.: trade name A4100) or a triacetyl cellulose (TAC) film with a thickness of 25 μm (manufactured by Konica Minolta: trade name KC2UA) was used as the base film. The breaking stress of the polyethylene terephthalate (PET) film used was 55 N/10 mm in the MD direction and 65 N/mm in the TD direction, and the breaking stress of the triacetyl cellulose (TAC) film was 35 N/10 mm.

The breaking stress of the optical function layer and base film was measured according to JIS-K-7161 using samples cut into 10 mm width.

<Active energy ray>
As the active energy ray, visible light (gallium-filled metal halide lamp) Irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc. Bulb: V bulb Peak illuminance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380- 440 nm) was used. The illuminance of visible light was measured using a Sola-Check system manufactured by Solatell.

(Adjustment of active energy ray-curable resin composition)
According to the recipes shown in Tables 1 to 5, each component shown below was mixed and stirred at 50° C. for 1 hour to obtain the active energy ray-curable resin composition used in Examples 1 to 16 and Comparative Examples 1 to 3. got Numerical values in the table indicate weight % when the total amount of the composition is 100 parts by mass.

Each material constituting the active energy ray-curable resin composition is shown below.
(1) (Meth)acrylate/unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone having a polar group (hydroxyl group); trade name “PLAXEL FA1DDM”, manufactured by Daicel Corporation, liquid viscosity 35 (mPa s), homopolymerized Initial Tg-45℃
・Polyethylene glycol-monoacrylate (acrylate having an average of 4.5 ethylene glycol units); trade name "Blemmer AE-200" manufactured by NOF Corporation, liquid viscosity 34 (mPa s), homopolymerization Tg-63°C
· Polypropylene glycol-monoacrylate (acrylate having an average of 3.5 propylene glycol units); trade name "Blemmer AP-200", manufactured by NOF Corporation, liquid viscosity 36 (mPa s), when homopolymerized Tg-40°C
· 1,4-cyclohexanedimethanol monoacrylate; trade name "CHDMMA", manufactured by Mitsubishi Chemical Corporation, liquid viscosity 88 (mPa s), Tg 18 ° C. when homopolymerized
· 4-hydroxybutyl acrylate; trade name "4HBA", manufactured by Mitsubishi Chemical Corporation, liquid viscosity 5.5 (mPa s), Tg -32 ° C. when homopolymerized
(2) (meth)acrylate having a polar group (carbonyl group) ω-carboxy-polycaprolactone monoacrylate (acrylate having an average of two C ₅ H ₁₀ COO units); trade name "Aronix M-5300", Toa Gosei Co., Ltd., liquid viscosity 130 (mPa s), Tg -41 ° C when homopolymerized
(3) (meth) acrylate having an alkylene glycol unit · polyethylene glycol-monoacrylate described above · polypropylene glycol-monoacrylate described above (4) polyfunctional (meth) acrylate · polyethylene glycol-diacrylate (ethylene glycol unit diacrylate having an average of 9); trade name “Light acrylate 9EG-A”, manufactured by Kyoeisha Chemical Co., Ltd., liquid viscosity 24 (mPa s), Tg −23 ° C. when homopolymerized
· Polypropylene glycol-diacrylate (diacrylate having an average of 7 propylene glycol units); trade name "Blemmer ADP-400" manufactured by NOF Corporation, liquid viscosity 25 (mPa s), Tg when homopolymerized -18°C
・ Ethoxylated glycerin triacrylate; trade name "NK Ester A-GLY-9E", manufactured by Shin-Nakamura Chemical Co., Ltd., liquid viscosity 100 (mPa s), Tg -25 ° C. when homopolymerized
・ 1.9-nonanediol diacrylate; trade name “Light Acrylate 1.9ND-A”, manufactured by Kyoeisha Chemical Co., Ltd., liquid viscosity 10 (mPa s), Tg 68 ° C. when homopolymerized
(5) Acrylic oligomer ・Product name “ARUFON UP-1190”, manufactured by Toagosei Co., Ltd., liquid viscosity 6000 (mPa s), Tg-50 ° C.
・ Product name “X MAP SA120S”, manufactured by Kaneka, liquid viscosity 70000 (mPa s), Tg-50 ° C.
(6) Other polymerizable components ・Butyl acrylate; liquid viscosity 2 (mPa s), Tg -55 ° C. when homopolymerized
・ Lauryl acrylate; liquid viscosity 5 (mPa s), Tg -3 ° C when homopolymerized
· N-acryloylmorpholine; trade name "ACMO", manufactured by Kojin Co., Ltd., liquid viscosity 12 (mPa s), Tg 145 ° C. when homopolymerized
・Hydroxyethyl acrylamide; trade name “HEAA”, manufactured by Kojin Co., Ltd., liquid viscosity 280 (mPa s), Tg 98 ° C. when homopolymerized
・Dicyclopentanyl acrylate; trade name “FA-513AS”, manufactured by Showa Denko Materials Co., Ltd., liquid viscosity 12 (mPa s), Tg 120 ° C. when homopolymerized
・ 4-vinylphenylboronic acid; manufactured by Tokyo Kasei Co., Ltd., liquid viscosity (solid at room temperature), Tg 100 ° C. or higher when homopolymerized (7) Silane coupling agent ・ 3-acryloxypropyltrimethoxysilane; manufactured by Shin-Etsu Silicone Co., Ltd. , trade name “KBM-5103”, liquid viscosity 2 (mPa s)
· 8-glycidoxyoctyltrimethoxysilane; manufactured by Shin-Etsu Silicone Co., Ltd., trade name "KBM-4803", liquid viscosity 5 (mPa s)
(8) Photoradical initiator Bis(2,4,6-trimethylbenzoyl)phenylphosphorine oxide; trade name "Omnirad 819", IGM Resins B.V. V. company, liquid viscosity (normal temperature solid)
2-methyl-4′-methylthio-2-morpholinopropiophenone; trade name “Omnirad 907”, IGM Resins B.V. V. company, liquid viscosity (normal temperature solid)
· 1-hydroxycyclohexyl-phenyl ketone; manufactured by Shin-Etsu Silicone Co., Ltd., trade name "Omnirad 184", IGM Resins B.V. V. company, liquid viscosity (normal temperature solid)
(9) Photoacid generator 4-methylphenyl[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate 75% propylene carbonate solution, trade name "Omnicat 250D", IGM Resins B.V. V. company, liquid viscosity 630 (mPa s)
(10) photosensitizer, diethylthioxanthone; trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd. (11) leveling agent, liquid viscosity (normal temperature solid)
・ Trade name “BYK-UV3505”, manufactured by BYK, liquid viscosity 596 (mPa s)

<Measurement of Tg and storage modulus of cured product layer of active energy ray-curable resin composition>
The active energy ray-curable resin composition used in Examples 1 to 16 and Comparative Examples 1 to 3 was applied to a cycloolefin polymer film (COP film) (thickness: 100 μm), and the same COP film was attached to the coated surface. At the same time, the active energy ray irradiator was used to irradiate the above visible light to obtain a cured product layer (single layer) of the active energy ray curable adhesive used in Examples 1 to 16 and Comparative Examples 1 to 3. Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, trade name “RSA-G2”), the storage elastic modulus of each single film was measured under the following conditions.
(Load mode): Tensile (heating rate): 5°C/min
(Frequency): 1Hz
(Initial strain): 0.1%
The Tg of each single film was obtained from the peak top temperature of tan δ obtained from the dynamic viscoelasticity measurement results obtained using the dynamic viscoelasticity measurement device. The results are shown in Tables 1-5.

(Fabrication of optical laminate)
Example 1
Using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, number of gravure roll lines: 1000 lines/inch, rotation speed 140%/relative to line speed), on the bonding surface of the PET film as the base film, The active energy ray-curable resin composition used in Example 1 was applied so as to have a thickness of 1.1 μm, and was bonded to the surface of the optical function layer using a roll machine. After that, the visible light was irradiated from the bonded substrate film side by an active energy ray irradiation device to cure the active energy ray-curable adhesive, thereby obtaining an optical laminate. The lamination line speed was 25 m/min. An optical laminate (PET) is obtained by using a PET film as a base film. An optical layered body manufactured in the same manner except that a TAC film was used as the base film instead of the PET film is referred to as an optical layered body (TAC).

Examples 2-16, Comparative Examples 1-3
Instead of the active energy ray-curable adhesive used in Example 1, the active energy ray-curable adhesive used in Examples 2 to 16 and Comparative Examples 1 to 3 was used, and the active energy ray-curable resin An optical layered body (PET) and an optical layered body (TAC) were produced in the same manner as in Example 1, except that the thickness of the composition was changed to that shown in the table.

<Evaluation of Adhesion of Optical Laminate>
The optical laminates (PET) and the optical laminates (TAC) according to Examples 1 to 16 and Comparative Examples 1 to 3 were coated with a reinforcing polyimide tape (manufactured by Nitto Denko Co., Ltd., polyimide adhesive tape No. 360A). A sample for measurement was produced by cutting a piece having a PET surface and a TAC surface of 15 mm wide. A glass plate to which double-sided tape (manufactured by Nitto Denko Co., Ltd., double-sided tape No. 500) is attached is prepared, and the optical functional layer surface (liquid crystal layer surface) of the prepared sample is attached to the double-sided tape on the glass plate to form an optical laminate. fixed on a glass plate. A cut was made with a cutter knife between the optical function layer and the base film (PET or TAC) of this measurement sample, and the base film (PET or TAC) and the polyimide tape for reinforcement were attached at 90 degrees to the glass plate surface. ° angle, and the force (N/15mm) required for peeling at a peeling speed of 3000mm/min was measured using an angle-variable type adhesive/film peeling analyzer "VPA-2" (manufactured by Kyowa Interface Chemical Co., Ltd.). It was measured.

(Preparation of adhesive layer)
63 parts by mass of 2-ethylhexyl acrylate (2EHA), 13 parts by mass of 2-hydroxyethyl acrylate (HEA), and methyl methacrylate (MMA) were placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. A monomer mixture containing 9 parts by weight and 15 parts by weight of N-vinylpyrrolidone (NVP) was charged. Further, 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts by weight of the monomer mixture (solid content) together with ethyl acetate, and nitrogen gas was introduced while gently stirring. After introducing and purging with nitrogen, the temperature of the liquid in the flask was kept around 55° C., and the polymerization reaction was carried out for 7 hours. Thereafter, ethyl acetate was added to the resulting reaction solution to prepare a solution of (meth)acrylic polymer 1 having a weight average molecular weight of 1,000,000, adjusted to a solid concentration of 30%.

1 mass of an isocyanate cross-linking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) per 100 parts by mass of the solid content of the (meth)acrylic polymer 1 solution obtained above and 0.08 parts by mass of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare an acrylic pressure-sensitive adhesive composition 1.

The acrylic pressure-sensitive adhesive composition 1 obtained above is evenly coated with a fountain coater on the surface of a 38 μm thick polyethylene terephthalate film (PET film, transparent substrate, separator) treated with a silicone release agent. and dried in an air circulation type constant temperature oven at 155° C. for 2 minutes to form an adhesive layer (25) with a thickness of 25 μm and an adhesive layer (50) with a thickness of 50 μm on the surface of the separator.

<Evaluation of Adhesion and Crack Resistance During Bending Test of Optical Layered Body in Humidified Environment>
The pressure-sensitive adhesive layer (50) was transferred from the separator to the TAC side of the optical laminates (TAC) according to Examples 1 to 16 and Comparative Examples 1 to 3, and the pressure-sensitive adhesive layer (25) was transferred from the separator to the cholesteric liquid crystal layer side. ) to produce an optical layered body having pressure-sensitive adhesive layers on both sides. Next, a corona-treated 25 μm-thick PET film (transparent substrate, manufactured by Mitsubishi Plastics Co., Ltd., trade name: Diafoil) was attached to the surface of the adhesive layer (25) of the optical laminate. Furthermore, by laminating a corona-treated 77 μm-thick polyimide film (PI film, manufactured by Toray-DuPont Co., Ltd., Kapton 300V, base material) on the surface of the pressure-sensitive adhesive layer (50), Examples 1 to 16 and Comparative Evaluation samples of optical laminates (TAC) according to Examples 1 to 3 were produced.

FIG. 2 shows a schematic diagram of a 180° folding endurance tester (manufactured by Imoto Seisakusho Co., Ltd.). This device has a mechanism in which the chuck on one side of the mandrel is repeatedly bent by 180° in a constant temperature bath, and the bending radius can be changed according to the diameter of the mandrel. It has a mechanism that stops the test when the film breaks. In the test, evaluation samples (5 cm × 15 cm) of the optical laminates (TAC) according to Examples 1 to 16 and Comparative Examples 1 to 3 manufactured above were placed on the outside (TAC on the mandrel side). It was set in an apparatus in such a manner that the temperature was 60° C. and the humidity was 95% RH. Evaluation conditions are as follows.
・When there was no peeling between the adhesive layer and the cholesteric liquid crystal layer and between the adhesive layer and the TAC even after the number of times of bending reached 200,000 → Adhesion in a humidified environment was 〇・Slight peeling between the adhesive layer and the cholesteric liquid crystal layer and/or between the adhesive layer and the TAC only in the folded area even after the number of times of folding reaches 200,000 (practical level) → Adhesion is △ in a humidified environment
・When the number of times of bending reaches 200,000 times, peeling occurs between the adhesive layer and the cholesteric liquid crystal layer and/or between the adhesive layer and the TAC (unpractical level) → in a humidified environment Adhesion is ×
・When no cracks occurred in the cholesteric liquid crystal layer and TAC even when the number of bends reached 200,000 times → crack resistance in a humidified environment was 〇・When the number of bends reached 200,000 times, the cholesteric liquid crystal When cracks occur in the layer → crack resistance under humid environment is ×
The results are shown in Tables 1-5.

From the results in Tables 1 to 5, the optical laminates according to Examples 1 to 16 not only exhibit excellent adhesion between each film and the adhesive layer at room temperature (23°C) when unfolded, but also exhibit excellent adhesion under a humidified environment. It can be seen that the adhesion is also excellent. In addition, it can be seen that the optical layered bodies according to Examples 1 to 16 are also excellent in crack resistance under a humid environment. On the other hand, in the optical laminates according to Comparative Examples 1 to 3, even though the adhesion between each film and the adhesive layer at room temperature (23° C.) when not folded is relatively good, adhesion under a humidified environment I know it gets worse. In Comparative Example 2, peeling occurred only in the bent region, but cracks occurred in the cholesteric liquid crystal layer. In Comparative Examples 1 and 3, the cholesteric liquid crystal layer was particularly peeled off, and cracks occurred in the cholesteric liquid crystal layer during the evaluation test.

Claims

An optical laminate in which an optical functional layer and a base film are laminated via an adhesive layer,
The optical function layer has a thickness of 0.5 to 5 μm,
The adhesive layer has a thickness of 0.5 to 3 μm,
The optical laminate, wherein the adhesive layer is formed of a cured product layer of an active energy ray-curable resin composition, and the cured product layer has a glass transition temperature of less than 30°C.
2. The optical laminate according to claim 1, wherein the active energy ray-curable resin composition contains 20 to 90 parts by mass of a (meth)acrylate having a polar group when the total amount of the composition is 100 parts by mass. body.
The optical laminate according to claim 2, wherein the polar group is a hydroxyl group or a carboxyl group.
Any one of claims 1 to 3, wherein the active energy ray-curable resin composition contains 5 to 90 parts by mass of (meth)acrylate having an alkylene glycol unit when the total amount of the composition is 100 parts by mass. The optical laminate according to any one of the above.
5. The active energy ray-curable resin composition according to any one of claims 1 to 4, which contains 3 to 20 parts by mass of a polyfunctional (meth)acrylate when the total amount of the composition is 100 parts by mass. optical laminate.
6. The optical laminate according to any one of claims 1 to 5, wherein the active energy ray-curable resin composition contains 3 to 20 parts by mass of an acrylic oligomer when the total amount of the composition is 100 parts by mass. body.
The active energy ray-curable resin composition contains 30 parts by mass or less of a polymer component having a glass transition temperature exceeding 30°C when homopolymerized, when the total amount of the composition is 100 parts by mass. The optical laminate according to any one of claims 1 to 6.
The optical laminate according to any one of claims 1 to 7, wherein the optical function layer is a liquid crystal layer.
The optical laminate according to any one of claims 1 to 8, comprising a folding region that is folded along a folding axis located between two non-folding regions.
The optical laminate according to claim 9, wherein the optical function layer is bent so as to be positioned on the outside.
An image display device using the optical laminate according to any one of claims 1 to 10.