KR20210028582A - Laminated optical film and image display device - Google Patents

Abstract

Disclosed is a laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer. The polarizer is located on the outer side of the second optical film. The adhesive layer differs in refractive index RF1 in the polarizer transmission axis direction on the polarizer side surface (F1) and the refractive index RF2 in the polarizer transmission axis direction on the second optical film side surface (F2). In the laminated optical film, the difference between the refractive index of RF1 and the polarizer transmission axis direction of the polarizer is within 0.05, and the difference of the refractive index of RF2 and the second optical film in the polarizer transmission axis direction is 0.05 or less.

Description

Laminated optical film and image display device TECHNICAL FIELD

The present invention relates to a laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer. This laminated optical film is suitable for an image display device, particularly an organic EL display device.

In order to improve visibility defects due to reflection of external light on a display screen of an image display device or reflection of a background, a display device in which a circular polarizing plate is disposed on the viewer side of a display panel is known. In Patent Documents 1 and 2, a polarizing film in which reflection of incident light from an oblique direction in black display is reduced, and an excellent color reflected in an oblique direction is realized, and a display device provided with the polarizing film are proposed.

Japanese Unexamined Patent Publication No. 2015-111236 Japanese Unexamined Patent Publication No. 2015-210459

However, in the display device using the polarizing film described in Patent Documents 1 and 2, there is a problem that nonuniformity occurs in reflected light, and visibility is insufficient.

In view of the above circumstances, an object of the present invention is to provide a laminated optical film having reduced reflectance from external light and excellent in visibility, and an image display device including the laminated optical film, particularly an organic EL display device.

The above problem can be solved by the following configuration. That is, the present invention is a laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer, wherein the polarizer is positioned outside the second optical film, and the adhesive layer is a polarizer-side surface ( F1) will have the polarizer transmission axis direction of the refractive index of R _F1 and the index of refraction of the polarizer transmission axis direction in the second optical film side surface (F2) R _F2 different in, of the polarizer transmission axis of the R _F1 and the polarizer direction It relates to a laminated optical film, wherein the difference in refractive index is within 0.05, and the difference in refractive index between R _F2 and the polarizer transmission axis direction of the second optical film is within 0.05.

In the laminated optical film, it is preferable that the thickness of the polarizer is 20 μm or less, and the thickness of the second optical film is 30 μm or less.

In the laminated optical film, it is preferable that the thickness of the adhesive layer is 5 μm or less.

Further, the present invention relates to an image display device, particularly an organic EL display device, provided with the laminated optical film described above.

The image display device includes a laminated optical film in which two or more optical films are laminated, and each optical film constituting such a laminated optical film is usually laminated through an adhesive layer. As a result of intensive examination by the present inventors, the adhesive layer provided by the conventionally existing laminated optical film is one optical film side (this is expressed as ``front side'') and the other optical film side (this is expressed as ``back side''). ), and in order to suppress reflection at the interface between the front optical film and the adhesive layer, and at the interface between the rear optical film and the adhesive, the concept of making the refractive index of the adhesive layer different from the front side and the back side has existed so far. Did not do it.

In the present invention, since the polarizer is positioned on the outer surface (viewing side) than the second optical film, when external light, particularly natural light, passes through the polarizer and enters it, the transmitted light becomes polarized light in the direction of the polarizer transmission axis. Here, in the present invention, in order to suppress reflection at the interface between each optical film and the adhesive layer, one having a different refractive index on the front side and the back side is used as such an adhesive layer. Specifically, an adhesive layer having a different _{refractive index R F1 in} the polarizer transmission axis direction in the polarizer side surface F1 and the refractive index R F2 in the polarizer transmission axis direction in the second optical film side surface _{F2 is used,} In addition, it is designed so that the difference between R _F1 and the refractive index in the polarizer transmission axis direction of the polarizer is within 0.05, _{and the difference between R F2} and the refractive index in the polarizer transmission axis direction of the second optical film is within 0.05. For this reason, since reflection at the interface between a polarizer and an adhesive layer, and an interface between a 2nd optical film and an adhesive layer can be suppressed remarkably, visibility improves.

In general, the thinner the laminated optical film is, the more easily unevenness occurs in reflected light, which is a problem.In particular, the laminated optical film according to the present invention, even if the thickness of the polarizer and the second optical film, and furthermore, the adhesive layer is thin, external light, In particular, it becomes possible to reduce the reflectance of natural light, and the visibility is also improved. Therefore, the laminated optical film according to the present invention is particularly useful for an image display device, particularly an organic EL display device.

1 is a diagram showing an example of reflection from external light in an image display device provided with a laminated optical film that has conventionally existed.
2 is a diagram showing an example of an image display device provided with a laminated optical film according to the present invention

In the present invention, in the laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer, in order to suppress reflection at the interface between each optical film and an adhesive layer, the front side and the back side as such an adhesive layer It is characterized in that the use of different refractive indices is used. These features will be described below, in contrast to a conventional image display device provided with a laminated optical film.

1 is a diagram showing an example _{of reflected light L R} from external light (natural light) L in an image display device provided with a laminated optical film that has conventionally existed. The image display device M shown in FIG. 1 is an organic EL image display device provided with an organic light-emitting diode 7, and a polarizer 3 and a second optical film 5 through the first adhesive layer 4 The laminated optical film 10 is provided. In the case of the conventional configuration shown in Fig. 1, the first adhesive layer 4 has the same refractive index on the front side and the back side, and the difference between the refractive index of the polarizer 3 and the refractive index of the first adhesive layer 4, furthermore, the first adhesive layer 4 The difference in the refractive index between the first adhesive layer 4 and the second optical film 5 is caused, and the interface between the polarizer 3 and the first adhesive layer 4, and the first adhesive layer 4 and the second optical Since the external light (natural light) L is reflected at the interface of the film 5, unevenness occurs in the reflected light, and the visibility becomes insufficient.

2 is a diagram showing an example of an image display device provided with a laminated optical film according to the present invention. The image display device M shown in FIG. 2 is an organic EL image display device including an organic light-emitting diode 7, and a first adhesive layer so that the polarizer 3 is positioned outside the second optical film 5. The laminated optical film 10 in which the polarizer 3 and the 2nd optical film 5 were laminated|stacked through (4) is provided. In addition, in the present invention, the laminated optical film may be composed of three or more optical films, and in the embodiment shown in Fig. 2(a), the image display device M is an organic light-emitting diode from the outermost side (viewing side). (7) In turn, transparent protective film (first optical film) (1) → second adhesive layer (2) → polarizer (3) → first adhesive layer (4) → retardation film (second optical film) ( 5) → A pressure-sensitive adhesive layer (6) is provided. As shown in Fig. 2(b), the first adhesive layer 4 included in the laminated optical film 10 according to the present invention has a refractive index R _{F1 in the polarizer transmission axis direction in the polarizer side surface F1 The refractive index R F2} in the polarizer transmission axis direction in the second optical film side surface F2 is different, and the difference in _{the refractive index in the polarizer transmission axis direction of R F1} and the polarizer is within 0.05, and R _F2 and the polarizer of the second optical film The difference in refractive index in the direction of the transmission axis is designed to be within 0.05. Accordingly, in the laminated optical film 10 according to the present invention, the reflectance of external light (natural light) (L) at the interface between the polarizer and the adhesive layer and the interface between the adhesive layer and the second optical film is reduced, and is excellent in visibility. Do.

<1st adhesive layer>

Hereinafter, an adhesive layer provided in the laminated optical film according to the present invention will be described. In the present invention, the thickness of the adhesive layer is preferably thinner, specifically, the thickness of the adhesive layer is preferably 5 µm or less, and more preferably 0.5 to 3 µm.

The adhesive layer provided in the laminated optical film according to the present invention is characterized in that the refractive index is different on the front side and the back side. _{Specifically, the refractive index R F1 in} the polarizer transmission axis direction in the polarizer side surface F1 and the refractive index R F2 in the polarizer transmission axis direction in the second optical film side surface _F2 are different, and further from R _F1 The difference between the refractive index of the polarizer in the polarizer transmission axis direction is within 0.05, _{and the difference between the refractive index between R F2} and the polarizer transmission axis direction of the second optical film is designed to be within 0.05. In order to further suppress reflection at the interface between the polarizer and the adhesive layer, and at the interface between the first optical film and the adhesive layer, the difference between R _F1 and the refractive index in the polarizer transmission axis direction of the polarizer is more preferably within 0.03, and R _F2 It is more preferable to make the difference between the refractive index of the polarizer transmission axis direction and the 2nd optical film within 0.03.

In the present invention, the "refractive index in the polarizer transmission axis direction" in the polarizer-side surface (F1) (or the second optical film-side surface (F2)) of the adhesive layer is the prism coupler SPA-4000 (Sylon Technology Co., Ltd.) was used to measure the refractive index in the direction of the polarizer transmission axis on each surface side of the adhesive layer. The measurement temperature was 23°C and the measurement wavelength was 532 nm.

In the present invention, the adhesive layer may be of any material design as long as it satisfies the above characteristics. In particular, it is preferable that the adhesive layer is formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray. In addition, an example of the manufacturing method of the adhesive layer which differs in the refractive index of the polarizer transmission axis direction from the front side and the back side is mentioned later. The active energy ray-curable adhesive composition can be broadly classified into an electron beam curing type, an ultraviolet curing type, and a visible ray curing type. Furthermore, the ultraviolet curing type and the visible ray curing type adhesive can be classified into a radical polymerization curing type adhesive and a cation polymerization type adhesive. In the present invention, active energy rays having a wavelength range of 10 nm to less than 380 nm are indicated as ultraviolet rays, and active energy rays having a wavelength range of 380 nm to 800 nm are indicated as visible rays.

Examples of the compound constituting the radical polymerization curable adhesive include radical polymerizable compounds. Examples of the radically polymerizable compound include compounds having a radically polymerizable functional group of a carbon-carbon double bond such as a (meth)acryloyl group and a vinyl group. These curable components can be used either as a monofunctional radical polymerizable compound or a bifunctional or more polyfunctional radical polymerizable compound. Moreover, these radically polymerizable compounds can be used individually by 1 type or in combination of 2 or more types. As these radical polymerizable compounds, for example, a compound having a (meth)acryloyl group is suitable. The active energy ray-curable adhesive composition used in the present invention preferably contains a compound having a (meth)acryloyl group as a main component, and specifically, the total amount of the active energy ray-curable adhesive composition is 100% by weight. In this case, it is preferable to contain 50% by weight or more of the compound having a (meth)acryloyl group, and more preferably 80% by weight or more. In addition, in this invention, (meth)acryloyl means an acryloyl group and/or a methacryloyl group, and "(meth)" has the same meaning as follows.

As a monofunctional radical polymerizable compound, a (meth)acrylamide derivative which has a (meth)acrylamide group is mentioned, for example. The (meth)acrylamide derivative not only secures adhesiveness with a polarizer and various transparent protective films, but also has a high polymerization rate and is preferable in terms of excellent productivity. Specific examples of the (meth)acrylamide derivative include, for example, N-methyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N- N-alkyl group-containing (meth)acrylamide derivatives such as isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, and N-hexyl (meth)acrylamide; N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-methylol-N-propane (meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl (meth)acrylamide and aminoethyl (meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; And N-mercaptoalkyl group-containing (meth)acrylamide derivatives such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide. In addition, as a heterocycle-containing (meth)acrylamide derivative in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle, for example, N-acryloylmorpholine, N-acryloylpiperidine, N -Methacryloylpiperidine, N-acryloylpyrrolidine, and the like.

Among the above (meth)acrylamide derivatives, from the viewpoint of adhesiveness to polarizers and various transparent protective films, an N-hydroxyalkyl group-containing (meth)acrylamide derivative is preferable, and as a monofunctional radical polymerizable compound, examples For example, various (meth)acrylic acid derivatives having a (meth)acryloyloxy group can be mentioned. 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)acrylic (Meth)acrylic acid (carbon number 1-20) alkyl esters such as acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate Can be mentioned.

Further, 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 Polycyclic (meth)acrylates such as (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbitol ( Alkoxy groups, such as meth)acrylate, phenoxyethyl (meth)acrylate, and alkylphenoxy polyethylene glycol (meth)acrylate, or (meth)acrylate containing a phenoxy group, etc. are mentioned.

In addition, as the (meth)acrylic acid derivative, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl ( Meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12 -Hydroxyalkyl (meth)acrylates such as hydroxylauryl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methylacrylate, cyclohexanedimethanol mono(meth)acrylate, 2- Hydroxyl group-containing (meth)acrylates such as hydroxy-3-phenoxypropyl (meth)acrylate; Epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth) Halogen-containing (meth)acrylates such as acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; Alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; 3-oxetanylmethyl(meth)acrylate, 3-methyl-oxetanylmethyl(meth)acrylate, 3-ethyl-oxetanylmethyl(meth)acrylate, 3-butyl-oxetanylmethyl(meth) ) Oxetane group-containing (meth)acrylates such as acrylate and 3-hexyl-oxetanylmethyl (meth)acrylate; Heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, butyrolactone (meth)acrylate, hydroxypivalate neopentyl glycol (meth)acrylic acid adduct, p-phenylphenol ( And meth)acrylate.

Further, examples of the monofunctional radical polymerizable compound include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Further, examples of the monofunctional radical polymerizable compound include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; Vinyl-based monomers having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

Moreover, as a monofunctional radically polymerizable compound, a radically polymerizable compound having an active methylene group can be used. The radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acryl group at the terminal or in the molecule and further having an active methylene group. Examples of the active methylene group include an acetoacetyl group, an alkoxymalonyl group, or a cyanoacetyl group. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include, for example, 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methyl. Acetoacetoxyalkyl (meth)acrylate such as ethyl (meth)acrylate; 2-Ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxy Butyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, N-(2-acetoacetylaminoethyl)acrylamide, and the like. It is preferable that the radically polymerizable compound having an active methylene group is acetoacetoxyalkyl (meth)acrylate.

In addition, as a polyfunctional radical polymerizable compound having a bifunctional or higher function, for example, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate , 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, 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, tri Cyclodecane dimethanol di(meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate )Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO modified diglycerin tetra (meth) acrylate, etc. ) Esterified products of acrylic acid and polyhydric alcohol, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Aronix M-220 (manufactured by Toa Synthetic Corporation), light acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), and light acrylate DCP. -A (manufactured by Kyoeisha Chemical), SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), and the like. Moreover, as needed, various epoxy (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, various (meth)acrylate-type monomers, etc. are mentioned.

When the active energy ray-curable adhesive composition uses an electron beam or the like for an active energy ray, the active energy ray-curable adhesive composition does not need to contain a photoinitiator, but uses ultraviolet rays or visible rays as the active energy ray. In the case, it is preferable to contain a photoinitiator.

The photoinitiator in the case of using a radically polymerizable compound is appropriately selected by an active energy ray. In the case of curing by ultraviolet or visible light, an ultraviolet or visible light cleavage photopolymerization initiator is used. The photopolymerization initiator may be used alone, but when a plurality of photopolymerization initiators are mixed and used, since the curing rate and curability can be adjusted, it is preferable. 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, 1 -Hydroxycyclohexylphenylketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{ Aromatic ketone compounds such as 4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one; Methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane Acetophenone compounds such as -1; Benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; Aromatic ketal compounds such as benzyl dimethyl ketal; Aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; Thioxanthone, 2-chloro thioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, 2,4-dichloro thioxanthone, 2,4-diethyl thioxanthone Thioxanthone compounds such as santon, 2,4-diisopropyl thioxanthone, and dodecyl thioxanthone; Camphor quinone; Halogenated ketones; Acylphosphinoside; Acylphosphonate, etc. are mentioned.

The blending amount of the photopolymerization initiator is 20% by weight or less when the total amount of the active energy ray-curable adhesive composition is 100% by weight. The blending amount of the photoinitiator is preferably 0.01 to 20% by weight, further preferably 0.05 to 10% by weight, and further preferably 0.1 to 5% by weight.

In addition, when using the curable adhesive for a laminated optical film of the present invention in a visible ray-curable type containing a radically polymerizable compound as a curable component, it is particularly preferable to use a photoinitiator that is highly sensitive to light of 380 nm or more. A photoinitiator that is highly sensitive to light of 380 nm or more will be described later.

As the photoinitiator, a compound represented by the following general formula (1);

[Formula 1]

(In the formula, R ¹ and R ² represent -H, -CH ₂ CH ₃ , -iPr or Cl, and R ¹ and R ² may be the same or different) alone, or a general formula (1 It is preferable to use together the compound represented by) and a photoinitiator which is highly sensitive to light of 380 nm or more to be described later. When the compound represented by the general formula (1) is used, the adhesiveness is excellent compared to the case where a photoinitiator having high sensitivity to light of 380 nm or more is used alone. Among the compounds represented by the general formula (1), diethylthioxanthone in which ^{R 1} and R ² are -CH ₂ CH _{3 is particularly preferable.} The composition ratio of the compound represented by the general formula (1) in the adhesive is preferably 0.1 to 5% by weight, more preferably 0.5 to 4% by weight, when the total amount of the active energy ray-curable adhesive composition is 100% by weight. It is preferable, and it is more preferable that it is 0.9-3 weight%.

Moreover, it is preferable to add a polymerization initiation aid as needed. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and 4-dimethylaminobenzoic acid. Somatomeal and the like, and ethyl 4-dimethylaminobenzoate is particularly preferred. When a polymerization initiation aid is used, the addition amount is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable component. .

Moreover, a known photoinitiator can be used together as needed. Since the transparent protective film having UV absorbing ability does not transmit light of 380 nm or less, it is preferable to use a photoinitiator with high sensitivity to light of 380 nm or more as the photoinitiator. Specifically, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-buta Non-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 Ro-3-(1H-pyrrol-1-yl)-phenyl) titanium and the like.

In particular, as a photoinitiator, in addition to the photoinitiator of the general formula (1), a compound further represented by the following general formula (2);

[Formula 2]

(In the formula, R ³ , R ⁴ and R ⁵ represent -H, -CH ₃ , -CH ₂ CH ₃ , -iPr or Cl, and R ³ , R ⁴ and R ⁵ may be the same or different) It is preferable to use. As the compound represented by the general formula (2), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (trade name: Omnirad907 manufacturer: IGMresins), which is also a commercial product, is suitably used. It is possible. Others, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (brand name: Omnirad369, manufacturer: IGMresins), 2-(dimethylamino)-2-[(4-methylphenyl) )Methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (trade name: Omnirad379, manufacturer: IGMresins) is preferable because of its high sensitivity.

In the present invention, among the photopolymerization initiators, it is preferable to use a hydroxyl group-containing photopolymerization initiator. When the active energy ray-curable adhesive composition contains a photopolymerization initiator containing a hydroxyl group as a polymerization initiator, the solubility in the adhesive layer having a high concentration of the component A on the polarizer side increases, and the curability of the adhesive layer increases. As a photoinitiator having a hydroxyl group, for example, 2-methyl-2-hydroxypropiophenone (trade name "DAROCUR1173", manufactured by IGMresins), 1-hydroxycyclohexylphenyl ketone (trade name "Omnirad184", IGMresins), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name "Omnirad2959", manufactured by IGMresins), 2 -Hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (trade name "Omnirad127", manufactured by IGMresins) And the like. In particular, 1-hydroxycyclohexylphenyl ketone is more preferable because it has particularly excellent solubility in an adhesive layer having a high concentration of component A.

The active energy ray-curable adhesive composition used in the present invention may contain an acrylic oligomer obtained by polymerizing a (meth)acrylic monomer in addition to the curable component related to the radical polymerizable compound. By containing an acrylic oligomer component in the active energy ray-curable adhesive composition, curing shrinkage is reduced when the composition is irradiated and cured with active energy rays, and interfacial stress between the adhesive and adherends such as polarizers and transparent protective films is reduced. It can be reduced. As a result, it is possible to suppress a decrease in adhesion between the adhesive layer and the adherend. In order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), when the total amount of the active energy ray-curable adhesive composition is 100% by weight, the content of the acrylic oligomer is preferably 5 to 30% by weight, and 10 It is more preferable to set it as-20 weight%.

When the active energy ray-curable adhesive composition considers workability and uniformity at the time of coating, it is preferable that it has a low viscosity, and therefore it is preferable that an acrylic oligomer obtained by polymerizing a (meth)acrylic monomer also has a low viscosity. As an acrylic oligomer having a low viscosity, it is preferable that the weight average molecular weight (Mw) is 15000 or less, more preferably 10000 or less, and particularly preferably 5000 or less. On the other hand, in order to further advance uneven distribution of the components of the adhesive composition interposed between the polarizer and the transparent protective film, the weight average molecular weight (Mw) of the acrylic oligomer (A) is preferably 500 or more, more preferably 1000 or more, and 1500 It is particularly preferable that it is above. As the (meth)acrylic monomer constituting the acrylic oligomer (A), 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 (meth)acrylate, N-octadecyl (meth)acrylate (Meth)acrylic acid (carbon number 1-20) alkyl esters such as, and, for example, cycloalkyl (meth)acrylate (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.) ), aralkyl (meth)acrylate (eg, benzyl (meth)acrylate, etc.), polycyclic (meth)acrylate (eg, 2-isobornyl (meth)acrylate, 2-norbor Nylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, etc.), containing a hydroxyl group (meth) Acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group Or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxy Butyl (meth)acrylate, ethylcarbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (eg, glycidyl (meth)acrylate, etc.) , Halogen-containing (meth)acrylic acid esters (for example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2 ,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl ( Meth)acrylate, etc.), alkylaminoalkyl (meth)acrylate (eg, dimethylaminoethyl (meth)acrylate), and the like. These (meth)acrylates can be used alone or in combination of two or more. Specific examples of the acrylic oligomer (A) include "ARUFON" manufactured by Toa Synthetic Company, "Actflow" manufactured by Soken Chemical Company, and "JONCRYL" manufactured by IGMresins.

When the acrylic oligomer is a liquid, since it is not necessary to consider the solubility in the adhesive composition, it is suitably used. The acrylic oligomer is usually liquid when the glass transition temperature (Tg) is less than 25°C. Moreover, in order to achieve both compatibility with the adhesive composition and the uneven distribution of the components in the adhesive layer, it is preferable that the acrylic oligomer contains a polar functional group. Examples of the polar functional group include a hydroxyl group, an epoxy group, a carboxyl group, and an alkoxysilyl group. Specifically, for example, "ARUFON UH series", "ARUFON UC series", "ARUFON UF series", "ARUFON UG series", "ARUFON US series" (all manufactured by Toa Synthetic Corporation), and the like. Among them, it is preferable to contain an epoxy group from the viewpoint of expecting an improvement in adhesiveness due to interaction with a polarizer. Specifically, "ARUFON UG-4000" and "ARUFON UG-4010" (all manufactured by Toa Synthetic Corporation) are mentioned, for example.

<polarizer>

The polarizer used in the present invention is not particularly limited, and various types of polarizers can be used. As a polarizer, for example, a dichroic material such as iodine or a dichroic dye is added to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene/vinyl acetate copolymer-based partial saponification film. Polyene-based oriented films, such as a thing which was adsorbed and uniaxially stretched, a polyvinyl alcohol dehydration treatment product, a polyvinyl chloride dehydrochloric acid treatment product, etc. are mentioned. Among these, a polarizer made of a polyvinyl alcohol-based film and a dichroic substance such as iodine is suitable.

In the present invention, the "refractive index in the direction of the polarizer transmission axis" of the polarizer is measured using a prism coupler SPA-4000 (manufactured by Silon Technology), among the refractive indexes in the plane of the polarizer, in the direction of the transmission axis. It was set as the refractive index in the direction of the polarizer transmission axis. The measurement temperature was 23°C and the measurement wavelength was 532 nm.

The thickness of the polarizer is generally 1 to 30 µm, but as described above, since the thinner the laminated optical film is more likely to cause unevenness in the reflected light, in particular, in the present invention, it is preferable that the polarizer is a thin polarizer, specifically It is preferable that it is 20 micrometers or less in thickness, and it is more preferable that it is 1-12 micrometers.

As a thin polarizer, representatively, Japanese Laid-Open Patent Publication No. 51-069644 or Japanese Laid-Open Patent Publication No. 2000-338329, a pamphlet of WO2010/100917, a specification of PCT/JP2010/001460, or Japanese Patent Application No. 2010-269002 The thin polarizing film described in the specification and Japanese Patent Application No. 2010-263692 can be mentioned. These thin polarizing films can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as a PVA-based resin) layer and a resin substrate for stretching in the state of a laminate and a step of dyeing. In this production method, even if the PVA-based resin layer is thin, it becomes possible to extend without problems such as fracture due to stretching by being supported by the resin substrate for stretching.

The thin polarizing film can be stretched at a high magnification to improve polarization performance, among the manufacturing methods including the step of stretching and dyeing in the state of a laminate. WO2010/100917 pamphlet, PCT/JP2010 It is preferably obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in the specification of /001460 or the specification of Japanese Patent Application 2010-269002 or specification of Japanese Patent Application 2010-263692, and in particular, Japanese Patent Application 2010 It is preferably obtained by a manufacturing method including a step of auxiliary air stretching before stretching in boric acid aqueous solution described in the specification of -269002 or the specification of Japanese Patent Application No. 2010-263692.

<2nd optical film>

The second optical film is not particularly limited, but, for example, a reflective film, a transflective film, a retardation film (including a wavelength film such as 1/2 or 1/4), a visual compensation film, etc. An optical layer that may be used for can be used. In the present invention, the thickness of the second optical film is preferably thinner, specifically, preferably 30 µm or less, and more preferably 1 to 20 µm.

In the present invention, the "refractive index in the polarizer transmission axis direction" of the retardation film (second optical film) is, using a prism coupler SPA-4000 (manufactured by Silon Technology), among the in-plane refractive indexes of the retardation film, the retardation film The refractive index in the transmission axis direction of the polarizer positioned further outside was measured, and this was made into the refractive index in the polarizer transmission axis direction. The measurement temperature was 23°C and the measurement wavelength was 532 nm.

The laminated optical film according to the present invention is characterized in that the refractive indexes in the polarizer transmission axis direction differ between the front side and the back side of the adhesive layer. The laminated optical film provided with such an adhesive layer can be manufactured by the following manufacturing method, for example.

A method for manufacturing a laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer, wherein the adhesive layer comprises a first cured product layer of a first adhesive composition and a second cured product layer of a second adhesive composition. A first step of coating the first adhesive composition on a bonding surface of the polarizer, wherein at least a part of the first adhesive composition and the second adhesive composition contain different components, A second step of coating the second adhesive composition on the bonding surface of the second optical film, and bonding the first adhesive composition coating surface of the polarizer and the second adhesive composition coating surface of the second optical film A manufacturing method comprising a third step and a fourth step of irradiating an active energy ray from the side of the polarizer surface or the side of the second optical film to bond the polarizer and the second optical film.

In the above manufacturing method, the adhesive layer comprises a first cured product layer of the first adhesive composition and a second cured product layer of the second adhesive composition, and the first adhesive composition and the second adhesive composition contain different components at least in part. Since it is contained, an adhesive layer different from _{the in-plane refractive index R F1} in the polarizer side surface F1 and the in-plane refractive index R _{F2 in the second optical film side surface F2 is formed.} Here, the refractive index in the polarizer transmission axis direction of the polarizer and the refractive index in the polarizer transmission axis direction of the second optical film can be measured in advance, and in the polarizer side surface (F1) of the first cured product layer of the first adhesive composition The refractive index R _F1 in the polarizer transmission axis direction of and the refractive index R _{F2 in} the polarizer transmission axis direction in the second optical film side surface F2 are also designed to be arbitrary values by performing the optimal combination design. Therefore, in the above manufacturing method, _{a laminated optical film comprising an adhesive layer in which the difference in the refractive index between R F1} and the polarizer in the transmission axis direction is within 0.05, and the difference _{between R F2} and the refractive index in the polarizer transmission axis direction of the second optical film is within 0.05 Can be manufactured.

Further, in the first step, with respect to the coated first adhesive composition, an active energy ray is irradiated from the side of the polarizer or the side of the coated side of the first adhesive composition of the polarizer, and the first adhesive composition is cured. The first cured material layer may be formed in advance, and the coated first adhesive composition is air-dried, or further, when the coated first adhesive composition contains a solvent, it is uncured in advance by removing the solvent. You may form the coating layer of the 1st adhesive composition of.

In the laminated optical film according to the present invention, the surface modification treatment of the polarizer and the second optical film may be performed before the first step and/or the second coating step (coating step). Specific treatments include corona treatment, plasma treatment, and saponification treatment.

Moreover, in the said 1st process and/or 2nd coating process (coating process), the coating method of an active energy ray-curable adhesive composition is suitably selected according to the viscosity of a composition and a target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, a method such as a dipping method can be appropriately used for coating.

In the said 3rd process (bonding process), two types of different optical films are bonded through the applied active energy ray-curable adhesive composition. The bonding of the optical film can be performed by, for example, a roll laminator.

In the fourth step (adhesion step), the active energy ray-curable adhesive composition can be used in an electron beam curing type, an ultraviolet curing type, or a visible ray curing type. As the active energy ray-curable adhesive composition, a visible ray-curable adhesive composition is preferable from the viewpoint of productivity.

In an active energy ray-curable adhesive composition, for example, after bonding a polarizer and a retardation film, an active energy ray (electron ray, ultraviolet ray, visible ray, etc.) is irradiated, and the active energy ray-curable adhesive composition is cured to form an adhesive layer. . The irradiation direction of an active energy ray (electron ray, ultraviolet ray, visible ray, etc.) can be irradiated from any suitable direction. Preferably, it irradiates from the phase difference film side. When irradiated from the polarizer side, there is a concern that the polarizer is deteriorated by active energy rays (electron rays, ultraviolet rays, visible rays, etc.).

In the electron beam curing type, any suitable condition can be adopted as long as the irradiation condition of the electron beam is a condition capable of curing the active energy ray-curable adhesive composition. For example, in electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, there is a risk that the electron beam does not reach the adhesive, resulting in insufficient curing. If the acceleration voltage exceeds 300 kV, the penetration force passing through the sample is too strong, causing damage to the retardation film or polarizer. have. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficient in curing, and when it exceeds 100 kGy, damage is given to the retardation film or polarizer, a decrease in mechanical strength or yellowing occurs, and predetermined optical properties cannot be obtained.

The electron beam irradiation is usually irradiated in an inert gas, but if necessary, it may be carried out in the atmosphere or under the condition of introducing a little oxygen. Depending on the material of the retardation film, by appropriately introducing oxygen, oxygen inhibition is generated on the plane of the retardation film to which the electron beam first touches, and damage to the retardation film can be prevented, so that only the adhesive can be efficiently irradiated with electron beams.

When manufacturing the laminated optical film according to the present invention, as an active energy ray, one containing visible light having a wavelength range of 380 nm to 450 nm, in particular, an active energy ray having the greatest irradiation amount of visible light having a wavelength range of 380 nm to 450 nm It is preferable to use. In the case of the ultraviolet curing type and the visible ray curing type, in the case of using a retardation film (ultraviolet non-transmissive retardation film) to which an ultraviolet absorbing ability is used, light having a wavelength shorter than 380 nm is absorbed, so that light having a wavelength shorter than 380 nm is an active energy ray curing type. It does not reach the adhesive and does not contribute to its polymerization reaction. Further, light having a wavelength shorter than that of 380 nm absorbed by the retardation film is converted into heat, and the retardation film itself generates heat, causing defects such as curls and wrinkles in the laminated optical film. Therefore, in the case of adopting an ultraviolet curing type or a visible ray curing type 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 generating device, and more specifically, a wavelength range of 380 It is preferable that it is 100:0-100:50, and it is more preferable that it is 100:0-100:40 ratio of the integrated illuminance of -440 nm and the integrated illuminance of the wavelength range 250-370 nm. As the active energy ray according to the present invention, a gallium-encapsulated metal halide lamp and an LED light source emitting light in a wavelength range of 380 to 440 nm are preferable. Alternatively, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, incandescent lamps, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, excimer lasers, ultraviolet rays and visible rays such as sunlight A light source including a may be used, and a band pass filter may be used to block ultraviolet rays having a wavelength shorter than 380 nm. In order to prevent curling of the laminated optical film while improving the adhesion performance of the adhesive layer between the polarizer and the retardation film, a gallium-encapsulated metal halide lamp is used, and a band pass filter capable of blocking light with a wavelength shorter than 380 nm is interposed. It is preferable to use the thus obtained active energy ray or an active energy ray having a wavelength of 405 nm obtained using an LED light source.

In the ultraviolet-curable or visible-ray-curable type, heating the active energy ray-curable adhesive after irradiation with ultraviolet or visible light (heating after irradiation) is also preferable, and in that case, heating to 40° C. or higher is preferable, and 50° C. or higher. It is more preferable to warm.

The active energy ray-curable adhesive used in the present invention can be particularly suitably used when forming an adhesive layer for bonding a polarizer and a retardation film having a light transmittance of less than 5% at a wavelength of 365 nm to form an adhesive layer. Here, when the active energy ray-curable adhesive according to the present invention contains the photopolymerization initiator of the above-described general formula (1), ultraviolet rays are irradiated over the retardation film having UV absorption ability to cure the adhesive layer. Therefore, also in the laminated optical film which laminated|stacked the retardation film which has UV absorption ability on both surfaces of a polarizer, the adhesive layer can be hardened. However, naturally, also in the laminated optical film which laminated|stacked the retardation film which does not have UV absorbing ability, the adhesive layer can be hardened. In addition, the retardation film having UV absorption ability means a retardation film in which the transmittance to light of 380 nm is less than 10%.

As a method of imparting the UV absorbing ability to the retardation film, a method of including an ultraviolet absorber in the retardation film, or a method of laminating a surface treatment layer containing an ultraviolet absorber on the surface of the retardation film may be mentioned.

Specific examples of the ultraviolet absorber include, for example, conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, and triazine compounds. Compounds, etc. are mentioned.

<2nd adhesive layer>

In the embodiment shown in FIG. 2, the 2nd adhesive layer 2 can be designed similarly to the said 1st adhesive layer. However, also in the 2nd adhesive layer 2, in order to suppress reflection at the interface with each optical film, it is preferable to use what is different in refractive index on the front side and the back side. Specifically, the transparent protective film (1) side surface (F3) in-plane refractive index of R _F3 and the polarizer (3) side surface (F4) in-plane refractive index R _F4 is using a different adhesive layers, and also R _F3 of the in It is preferable to design so that the difference between the in-plane average refractive index of the translucent protective film 1 is within 0.05, and the difference between the in-plane average refractive index of R _{F4 and the polarizer 3 is within 0.05.} In this case, the reflectance is reduced in the entire image display device M, and visibility is remarkably improved. In the present invention, the ``in-plane average refractive index'' of the polarizer is a prism coupler SPA-4000 (manufactured by Silon Technology), and among the in-plane refractive indexes of the polarizer, the refractive index in the transmission axis direction and the absorption axis direction are measured. And these average values are made into the in-plane average refractive index of a polarizer. The measurement temperature is 23°C and the measurement wavelength is 532 nm.

<Transparent protective film>

The thickness of the transparent protective film is preferably thinner, specifically, preferably 30 µm or less, and more preferably 1 to 20 µm. As a transparent protective film, it is preferable that it is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, and the like. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene or acrylonitrile-styrene copolymer Styrene polymers, such as (AS resin), polycarbonate polymers, etc. are mentioned. In addition, polyethylene, polypropylene, polyolefin having a cyclo-based or norbornene structure, polyolefin-based polymer such as ethylene-propylene copolymer, vinyl chloride-based polymer, amide-based polymer such as nylon or aromatic polyamide, imide-based polymer, alcohol Pone polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, Epoxy polymers, blends of the polymers, etc. are also exemplified as examples of polymers forming the transparent protective film. One or more types of arbitrary suitable additives may be contained in the transparent protective film. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, particularly preferably 70 to 97% by weight. . When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, there is a fear that the high transparency inherent in the thermoplastic resin cannot be sufficiently expressed.

In addition, as a transparent protective film, a polymer film described in JP 2001-343529 A (WO01/37007), for example, (A) a thermoplastic resin having a substituted and/or unsubstituted imide group in the side chain, And a resin composition containing a thermoplastic resin having a substituted and/or unsubstituted phenyl and nitrile group in the side chain. As a specific example, a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer is exemplified. As the film, a film made of a mixed extruded product of a resin composition or the like can be used. Since these films have a small retardation and a small photoelastic modulus, problems such as unevenness due to deformation of the polarizing film can be solved, and since the moisture permeability is small, they are excellent in humidification durability.

In addition, the "in-plane average refractive index" of the transparent protective film in the present invention uses a prism coupler SPA-4000 (manufactured by Silon Technology), and among the in-plane refractive indexes of the transparent protective film, the refractive index in the fast axis direction and the slow axis direction The refractive index of was measured, and these average values were made into the in-plane average refractive index. The measurement temperature was 23°C and the measurement wavelength was 532 nm.

<Adhesive layer>

In the embodiment shown in FIG. 2, the above-described transparent protective film (first optical film) (1), first adhesive layer (2), polarizer (second optical film) (3), and second adhesive layer (4) And the laminated optical film provided with the retardation film (third optical film) 5 is laminated|stacked on the organic light-emitting diode 7 via the adhesive layer 6. The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyamide, polyether, a fluorine-based or rubber-based polymer can be appropriately selected and used as a base polymer. have. In particular, those having excellent optical transparency, appropriate wettability, cohesiveness and adhesive properties, such as an acrylic pressure-sensitive adhesive, and excellent weather resistance and heat resistance, can be preferably used.

The adhesive layer may be formed on one side or both sides of a polarizing film or an optical film as an overlapping layer of different compositions or types. Moreover, in the case of forming on both sides, it is also possible to use an adhesive layer such as a different composition, type, or thickness on the front and back of a polarizing film or an optical film. 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, and particularly preferably 1 to 100 µm.

With respect to the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination or the like until it is provided for practical use. Accordingly, it is possible to prevent contact with the adhesive layer in the usual handling state. As the separator, except for the above-described thickness conditions, for example, suitable thin-walled materials such as plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet or metal foil, and laminates thereof may be used as necessary, such as silicone or long chains. A suitable one according to the prior art, such as one coated with an appropriate release agent such as an alkyl-based, fluorine-based or molybdenum sulfide, can be used.

<Image display device>

The laminated optical film of the present invention can be suitably used for the formation of various image display devices such as an organic EL imaging device or a liquid crystal display device. The formation of the image display device can be carried out according to the prior art. That is, an image display device is generally formed by properly assembling components such as an organic light emitting diode or a liquid crystal cell, a laminated optical film, and a lighting system as necessary to attach a driving circuit, but in the present invention, the present invention There is no restriction|limiting in particular except for using the laminated optical film by, and it can follow conventionally.

When the laminated optical film of the present invention is used in a liquid crystal display device, a liquid crystal display device in which a laminated optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector is used in a lighting system, etc. can do. In that case, the laminated optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When forming a laminated optical film on both sides, they may be the same thing or different things may be sufficient. In addition, when forming a liquid crystal display, for example, a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc. It can be placed above.

Example

In Examples 1-3 and Comparative Example 1 shown below, a laminated optical film was model-designed by simulation. For the simulation, a commercially available liquid crystal simulator "LCD master (manufactured by Syntech Co., Ltd.)" was used. In addition, the optical calculation algorithm was set to a 4x4 Jones matrix method. Moreover, the thing of 380 nm-780 nm was used as incident light (random light) from the 1st optical film side with respect to a laminated optical film.

(Polarizer)

As the polarizer, a polarizer having a refractive index of 1.52 in the direction of the transmission axis of the polarizer of 550 nm (thickness 5 μm) was used.

(2nd optical film (phase difference film))

As a 2nd optical film, the thing of the retardation film (thickness 1.5 micrometers) of the refractive index of 1.65 in the polarizer transmission axis direction of 550 nm was used.

Examples 1 to 3

Using LCD Master, and the in-plane refractive index R _F2 at the polarizer side surface (F1) in-plane refractive index of R _F1 and the second optical film side surface (F2) of the design of the adhesive layer which is a value described in Table 1, The laminated optical film in which the 1st optical film and the 2nd optical film were laminated was designed through such an adhesive layer, and the reflectance when irradiating random light from the 1st optical film side with respect to the laminated optical film was calculated. Table 1 shows the results.

Comparative Example 1

Using an LCD master, to design an adhesive layer (single-layer adhesive layer) having a constant in-plane refractive index in the thickness direction, and design a laminated optical film in which the first optical film and the second optical film are laminated through the adhesive layer, The reflectance was calculated. Table 1 shows the results.

From the results of Table 1, in the laminated optical films according to Examples 1 to 3, because |R _(a) -R _F1 | and |R _(b) -R _F2 | are designed to be within 0.05, external light (random light) It turns out that the reflectance when incident on this laminated optical film is low and visibility is excellent. On the other hand, in the laminated optical film according to the comparative example corresponding to the conventional laminated optical film, since |R _{(b) -RF2} | exceeds 0.05, it turns out that the reflectance is large and visibility is bad.

Claims (5)

As a laminated optical film in which at least a polarizer and a second optical film are laminated through an adhesive layer,
The polarizer is positioned outside the second optical film,
The adhesive layer is, assumes that the refractive index of R _F2 of the polarizer transmission axis direction in the polarizer side surface (F1) the refractive index R _F1 and the second optical film side surface (F2) of the polarizer transmission axis direction in the different,
A laminated optical film, characterized in that the difference between the refractive indexes of the R _F1 and the polarizer in the transmission axis direction of the polarizer is within 0.05, and the difference between the refractive indexes of the R _{F2 and the second optical film in the polarizer transmission axis direction is within 0.05.} The method of claim 1,
A laminated optical film having a thickness of the polarizer of 20 μm or less and a thickness of the second optical film of 30 μm or less. The method according to claim 1 or 2,
A laminated optical film having a thickness of the adhesive layer of 5 μm or less. An image display device provided with the laminated optical film according to claim 1 or 2. An organic EL display device comprising the laminated optical film according to claim 1 or 2.

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