Optical film with an adhesive layer and an image display device including the optical film with an adhesive layer

Abstract

To provide an optical film which is thin and in which decoloration is suppressed.SOLUTION: An optical film with adhesive layer comprises a polarizing plate including a polarizer and a protective layer arranged on at least one side of the polarizer, a retardation layer and an adhesive layer in this order from the viewing side. The moisture vapor permeability of the retardation layer is equal to or greater than 300 g / m2 / 24h. In the cross-sectional view, the end of the adhesive layer is located on the inner side with respect to the end of the polarizer. The horizontal distance between the end of the adhesive layer and the end of the polarizer is between 0 μm and 50 μm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical film with an adhesive layer and an image display device including the optical film with the adhesive layer.

Background Art

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. In an organic EL display device equipped with an organic EL panel, since the organic EL panel has a highly reflective metal layer, problems such as external light reflection and background reflection are likely to occur. Therefore, it is known to prevent these problems by providing a circular polarizing plate including a λ / 4 plate on the viewing side (for example, Patent Documents 1 to 3).

[0003] As the above circular polarizing plate, excellent antireflection characteristics can be realized by using a λ / 4 plate having reverse wavelength dispersion characteristics. On the other hand, from the viewpoint of thinning of the image display device, there is a demand for thinning of the circular polarizing plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] For the purpose of thinning the circular polarizing plate, when the present inventors produced a circular polarizing plate using a thin λ / 4 plate, it was found that the moisture permeability of the λ / 4 plate increased, and as a result, discoloration was likely to occur at the ends compared with the conventional circular polarizing plate.

[0006] The present invention has been made to solve the above problems, and its main object is to provide an optical film that is thin and has suppressed discoloration.

Means for Solving the Problems

[0007] Optical films such as circular polarizing plates are usually provided with an adhesive layer for bonding to an image display cell. As a result of intensive studies to achieve the above object, the inventors of the present invention have found that when cutting an optical film with an adhesive layer into a desired shape, chipping occurs at the end of the adhesive layer and the retardation layer is exposed, which affects the discoloration of the polarizer. They have also obtained the idea that the discoloration can be suppressed by controlling the chipping at the end of the adhesive layer within a predetermined range, and thus completed the present invention.

[0008] According to one aspect of the present invention, there is provided an optical film with an adhesive layer, comprising a polarizing plate including a polarizer and a protective layer disposed on at least one side of the polarizer, a retardation layer, and an adhesive layer, which are provided in this order from the viewing side, wherein the moisture permeability of the retardation layer is 300 g / m 2 ·24 h or more, and in a cross-sectional view, the end of the adhesive layer is located inward of the end of the polarizer, and the horizontal distance between the end of the adhesive layer and the end of the polarizer is 0 μm to 50 μm. In one embodiment, the polarizing plate includes the polarizer and a protective layer disposed only on the viewing side of the polarizer. In one embodiment, the thickness of the polarizer is 10 μm or less. In one embodiment, when stress-strain measurement is performed on the adhesive layer at 23°C, the strain amount at a stress of 0.4 N is 900% or less. In one embodiment, the retardation layer includes an alignment cured layer of a liquid crystal compound, Re(550) and Re(450) of the alignment cured layer of the liquid crystal compound satisfy the relationship of 0.8 ≦ Re(450) / Re(550) < 1, Re(550) of the alignment cured layer of the liquid crystal compound is 100 nm to 190 nm, and the angle formed by the slow axis of the alignment cured layer of the liquid crystal compound and the absorption axis of the polarizer is 40° to 50°. According to one aspect of the present invention, there is provided an image display device including the above optical film with an adhesive layer. In one embodiment, the image display device is an organic electroluminescence display device.

Effects of the Invention

[0009] According to the optical film with an adhesive layer of the present invention, as a result of suppressing the exposure of the retardation layer, even when a thin retardation layer is used, decoloration of the polarizer can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0012] (Definitions of Terms and Symbols) The definitions of terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction. (2) In-Plane Retardation (Re) “Re(λ)” is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, “Re(550)” is the in-plane retardation measured with light of wavelength 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx - ny)×d when the thickness of the layer (film) is d (nm). (3) Retardation in the Thickness Direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. When the thickness of the layer (film) is d (nm), Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d. (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0013] A. Overall configuration of the optical film with an adhesive layer FIG. 1 is a schematic cross-sectional view of an optical film with an adhesive layer according to one embodiment of the present invention. The optical film 100A with an adhesive layer in the illustrated example has a polarizing plate 10, a retardation layer 20, and an adhesive layer 30 in this order from the viewing side. The polarizing plate 10 includes a polarizer 11, a protective layer (outer protective layer) 12 provided on the viewing side of the polarizer 11, and a protective layer (inner protective layer) 13 provided on the side opposite to the viewing side of the polarizer 11. The protective layer 13 may be omitted depending on the purpose or the like. For example, when the retardation layer 20 can also serve as the protective layer of the polarizer 11, the protective layer 13 can be omitted.

[0014] FIG. 2 is a schematic cross-sectional view of an optical film with an adhesive layer according to another embodiment of the present invention. The optical film 100B with an adhesive layer in the illustrated example has a polarizing plate 10, a retardation layer 20, and an adhesive layer 30 in this order from the viewing side. The polarizing plate 10 includes a polarizer 11 and an outer protective layer 12, and the inner protective layer is omitted. In this embodiment, the retardation layer 20 has a laminated structure including a first retardation layer 20a and a second retardation layer 20b, and the retardation layer 20 (substantially, the first retardation layer 20a) also serves as the protective layer of the polarizer 11. Since the decoloration of the polarizer is likely to occur when the retardation layer is exposed in the optical film with an adhesive layer in which the inner protective layer is omitted, compared with the optical film with an adhesive layer in which the inner protective layer is provided, the effects of the present invention can be more preferably obtained.

[0015] In an embodiment of the present invention, the moisture permeability of the retardation layer 20 is 300 g / m 2 ·24 h or more, and in a cross-sectional view, the end of the adhesive layer 30 is located inward of the end of the polarizer 11. Here, "located inward" includes being at the same position, and in a cross-sectional view, it is allowed that the end of the adhesive layer 30 is located on the same vertical line as the end of the polarizer 11. More specifically, in a cross-sectional view, when the position of the end of the polarizer 11 is P1 and the position of the end of the adhesive layer 30 is P2, P1 and P2 are on the same vertical line, or P2 is located inward of P1, and the distance (horizontal distance) D between P1 and P2 is 50 μm or less. The distance D between P1 and P2 is preferably short and can be 0 μm to 40 μm, 0 μm to 35 μm, 0 μm to 30 μm, or 0 μm to 25 μm. By suppressing the exposure of the end of the retardation layer 20 due to chipping or the like of the adhesive layer 30 during cutting, it is possible to suppress the decoloration of the polarizer 11 even when a retardation layer having a high moisture permeability is used.

[0016] The retardation layer 20 and the polarizing plate 10 are typically bonded via an adhesive layer such as an adhesive layer or an adhesive layer. In a cross-sectional view, it is preferable that the end of the adhesive layer is located inward of the end of the polarizer. The distance (horizontal distance) between the position of the end of the polarizer and the position of the end of the adhesive layer is preferably short and can be, for example, 0 μm to 50 μm, 0 μm to 40 μm, 0 μm to 35 μm, 0 μm to 30 μm, or 0 μm to 25 μm. By suppressing the exposure of the polarizing plate due to chipping or the like of the end of the adhesive layer, the decoloration suppression effect of the polarizer can be more preferably obtained. In addition, the ends of the protective layer and the retardation layer are preferably on the same vertical line as the end of the polarizer in a cross-sectional view.

[0017] Although not shown, it is preferable that a release film is temporarily attached to the surface of the adhesive layer until the optical film with an adhesive layer is put into use. Further, the optical film with an adhesive layer may further include other optical functional layers. The type, characteristics, number, combination, arrangement position, etc. of the optical functional layers that can be provided on the optical film with an adhesive layer can be appropriately set according to the purpose.

[0018] The total thickness of the optical film with an adhesive layer is preferably 120 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. The lower limit of the total thickness can be, for example, 45 μm. The optical film with an adhesive layer having such a total thickness can contribute to the thinning of the image display device and can have excellent flexibility and bending durability, so it can be suitably applied to a curved image display device and / or an image display device that can be bent or folded.

[0019] In one embodiment, the optical film with an adhesive layer is a sheet-like film cut to a predetermined size. Since the optical film with an adhesive layer according to the embodiment of the invention has less chipping of the adhesive layer due to shear stress during cutting, decoloration of the end portion of the polarizer after being cut into a sheet shape can be suppressed. As the cutting method, any appropriate method such as punching, milling such as full-back processing, and FFC processing can be adopted.

[0020] Hereinafter, the components of the optical film with an adhesive layer will be described in more detail.

[0021] B. Polarizer B-1. Polarizing film As the polarizing film 11, any appropriate polarizing film can be adopted. For example, the polarizing film may be composed of a single-layer resin film or may be obtained using a laminate of two or more layers.

[0022] Specific examples of the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based resin films, partially formalized PVA-based resin films, and ethylene-vinyl acetate copolymer-based partially saponified films, which are subjected to dyeing treatment with dichroic substances such as iodine and dichroic dyes and stretching treatment, and polyene-based oriented films such as dehydrated products of PVA and dehydrochlorinated products of polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based resin film with iodine and uniaxially stretching it is used because of its excellent optical properties.

[0023] The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based resin film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment, or may be performed while dyeing. Also, dyeing may be performed after stretching. If necessary, a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment, etc. are performed on the PVA-based resin film. For example, by immersing the PVA-based resin film in water and washing it before dyeing, not only can the dirt and blocking inhibitor on the surface of the PVA-based resin film be washed, but also the PVA-based resin film can be swollen to prevent uneven dyeing.

[0024] As specific examples of the polarizer obtained using the laminate, there may be mentioned a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a polarizer obtained using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material. The polarizer obtained using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material can be produced, for example, by coating a PVA-based resin solution on the resin base material and drying it to form a PVA-based resin layer on the resin base material to obtain a laminate of the resin base material and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer; and the like. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Further, stretching may further include, if necessary, air stretching the laminate at a high temperature (for example, 95° C. or higher) before stretching in the aqueous boric acid solution. The obtained laminate of the resin base material / polarizer may be used as it is (that is, the resin base material may be used as a protective layer of the polarizer), or the resin base material may be peeled off from the laminate of the resin base material / polarizer, and an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of such a method for manufacturing a polarizer are described, for example, in JP-A-2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

[0025] The thickness of the polarizer is, for example, 25 μm or less, preferably 10 μm or less, and more preferably 8 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and still more preferably 3 μm or more.

[0026] The polarizer preferably exhibits absorption dichroism at any wavelength in the wavelength range of 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

[0027] B-2. Protective layer The outer protective layer 12 and the inner protective layer 13 (when present) are each composed of any suitable film that can be used as a protective layer for the polarizer. Representative examples of the material constituting the inner protective layer 13 include cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. Representative examples of the (meth)acrylic resin include (meth)acrylic resins having a lactone ring structure. The (meth)acrylic resin having a lactone ring structure is described, for example, in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005-146084. These publications are incorporated herein by reference. The inner protective layer 13 is preferably composed of a cycloolefin resin. Representative examples of the material constituting the outer protective layer 12 include cellulose resins such as triacetyl cellulose (TAC), and resins that can form a microporous film (for example, polyurethane resins).

[0028] As described later, the optical film with an adhesive layer can be disposed on the viewing side of an image display device (typically, an organic EL display device) such that the outer protective layer faces the viewing side. Therefore, the outer protective layer may be subjected to surface treatments such as hard coat treatment, antireflection treatment, anti-sticking treatment, and antiglare treatment, as necessary. Further / alternatively, the outer protective layer may be subjected to a treatment (typically, imparting an (elliptical) polarization function or a super high retardation) for improving visibility when viewing through polarized sunglasses, as necessary. By performing such a treatment, excellent visibility can be achieved even when viewing the display screen through a polarizing lens such as polarized sunglasses. Therefore, the optical film with an adhesive layer can also be suitably applied to an image display device that can be used outdoors.

[0029] The thickness of the outer protective layer is preferably 10 μm to 80 μm, more preferably 15 μm to 70 μm, and even more preferably 20 μm to 50 μm. When surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

[0030] In one embodiment, the inner protective layer is preferably optically isotropic. As used herein, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the retardation in the thickness direction Rth(550) is -10 nm to +10 nm. The thickness of the inner protective layer is preferably 10 μm to 80 μm, more preferably 20 μm to 70 μm, and even more preferably 30 μm to 50 μm.

[0031] C. Retardation layer As shown in FIG. 1, the retardation layer 20 can be a single layer. The retardation layer 20 may also have a laminated structure of a first retardation layer 20a and a second retardation layer 20b as shown in FIG. 2, or may have a laminated structure of three or more layers.

[0032] The moisture permeability of the retardation layer (in the case of a laminated structure, the moisture permeability of the entire laminate) is, for example, 300 g / m 2 ·24 h or more, and also, for example, 350 g / m 2 ·24 h to 700 g / m 2 ·24 h. When a retardation layer having such humidity is used, the effects of the present invention can be preferably obtained.

[0033] The thickness of the retardation layer (in the case of a laminated structure, the total thickness) can be appropriately set according to the purpose. The thickness of the retardation layer is preferably 1 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 2 μm to 8 μm. One of the features of the present invention is that even when a retardation layer that is thin and has a large moisture permeability is used, discoloration at the ends of the polarizer can be suppressed.

[0034] When the retardation layer 20 is a single layer, the retardation layer can typically function as a λ / 4 plate. The retardation layer typically exhibits a refractive index characteristic where nx > ny = nz. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 120 nm to 160 nm. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny > nz or ny < nz may occur.

[0035] The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying such a relationship, an organic EL display device having a very excellent reflection hue can be obtained.

[0036] The retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized.

[0037] The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is within such a range, by using the retardation layer as a λ / 4 plate as described above, an organic EL display device having very excellent antireflection characteristics can be obtained.

[0038] The retardation layer can be composed of any suitable material as long as it can satisfy the above characteristics. Specifically, the retardation layer may be an alignment and curing layer of a liquid crystal compound (hereinafter, a liquid crystal alignment and curing layer), or a stretched film of a resin film.

[0039] When the phase difference layer is a liquid crystal alignment cured layer, by using a liquid crystal compound, the difference between nx and ny of the obtained phase difference layer can be made significantly larger than that of a non-liquid crystal material. Therefore, the thickness of the phase difference layer for obtaining a desired in-plane phase difference can be made significantly smaller. As a result, further thinning of the optical film with an adhesive layer (and as a result, the image display device) can be achieved. In this specification, the "alignment cured layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. Note that the "alignment cured layer" is a concept that includes an alignment cured layer obtained by curing a liquid crystal monomer. In this embodiment, typically, rod-shaped liquid crystal compounds are aligned in a state parallel to the slow axis direction of the phase difference layer (homogeneous alignment). Specific examples of the liquid crystal compound and details of the method for forming the liquid crystal alignment cured layer are described in, for example, JP-A-2006-163343 and JP-A-2006-178389. The descriptions in these publications are incorporated herein by reference.

[0040] The thickness of the phase difference layer composed of a single layer of the liquid crystal alignment cured layer can be, for example, 1 μm to 5 μm.

[0041] When the phase difference layer 20 has a laminated structure of a first phase difference layer 20a and a second phase difference layer 20b, as the first phase difference layer, a phase difference layer that can function as a λ / 4 plate with the above single layer is preferably used. The angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°.

[0042] The second retardation layer can be a so-called positive C-plate showing a refractive index characteristic of nz > nx = ny. By using a positive C-plate as the second retardation layer, reflection in an oblique direction can be well prevented, and a wide viewing angle of the antireflection function can be achieved. In this case, the retardation Rth(550) in the thickness direction of the second retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, still more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, "nx = ny" includes not only the case where nx and ny are exactly equal but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re(550) of the second retardation layer can be less than 10 nm.

[0043] The second retardation layer having a refractive index characteristic of nz > nx = ny can be formed of any suitable material. The second retardation layer preferably comprises a film containing a liquid crystal material fixed in a homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compounds and the method for forming the retardation layer described in

[0020] to

[0028] of JP-A-2002-333642. In this case, the thickness of the second retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, still more preferably 0.5 μm to 5 μm.

[0044] D. Adhesive layer As the adhesive layer, an adhesive layer having relatively high elasticity and little glue shortage due to cutting is preferably used.

[0045] The strain amount at a stress of 0.4 N when measuring stress-strain at 23°C of the adhesive layer is, for example, 900% or less, preferably 800% or less, more preferably 200% to 600%, and still more preferably 200% to 400%.

[0046] The creep value of the adhesive layer at 85°C is preferably 80 μm or less, more preferably 1 μm to 60 μm, and even more preferably 1 μm to 50 μm. The creep value can be measured by the method described in the examples.

[0047] The storage elastic modulus G' of the adhesive layer at 25°C is preferably 1.00×10 5 Pa or more, more preferably 1.10×10 5 Pa or more, and preferably 2.00×10 6 Pa or less.

[0048] The storage elastic modulus G' of the adhesive layer at 85°C is preferably 7.00×10 4 (Pa) or more, more preferably 1.00×10 5 Pa or more, even more preferably 1.50×10 5 Pa or more, and preferably 5.50×10 6 Pa or less.

[0049] The moisture permeability of the adhesive layer is, for example, 2500 g / m 2 ·24 h or less, preferably 100 g / m 2 ·24 h to 2000 g / m 2 ·24 h.

[0050] The thickness of the adhesive layer is, for example, 5 μm to 50 μm, preferably 5 μm to 35 μm, and more preferably 5 μm to 25 μm.

[0051] Examples of the adhesive for forming the adhesive layer include rubber-based adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, etc. The tacky base polymer is selected according to the type of the adhesive. Among the adhesives, acrylic adhesives are preferably used because of their excellent optical transparency and adhesion characteristics.

[0052] The acrylic adhesive contains a (meth)acrylic polymer as a base polymer. The (meth)acrylic polymer usually contains an alkyl (meth)acrylate as a main component as monomer units. Note that (meth)acrylate means acrylate and / or methacrylate, which has the same meaning as (meth) in this specification.

[0053] Examples of the alkyl (meth)acrylate that constitutes the main skeleton of the (meth)acrylic polymer include those having 1 to 18 carbon atoms in a linear or branched alkyl group. These can be used alone or in combination. The average carbon number of these alkyl groups is preferably 3 to 9.

[0054] Also, from the viewpoints of adhesion characteristics, durability, adjustment of phase difference, adjustment of refractive index, etc., alkyl (meth)acrylates containing an aromatic ring such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate can be used as copolymerization monomers.

[0055] In the (meth)acrylic polymer, for the purpose of improving adhesiveness and heat resistance, one or more copolymerizable monomers having polymerizable functional groups with unsaturated double bonds such as (meth)acryloyl groups or vinyl groups can be introduced by copolymerization. Specific examples of such copolymerizable monomers include, for example, hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate; carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate, etc.

[0056] Also, (N-substituted) amide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide; alkylaminoalkyl (meth)acrylate-based monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate-based monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide, and N-acryloylmorpholine; maleimide-based monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide can also be mentioned as copolymerization monomers.

[0057] Furthermore, as other copolymerizable monomers, vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methyl vinylpyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N-vinyl carboxamides, styrene, α-methylstyrene, N-vinyl caprolactam; cyanoacrylate monomers such as acrylonitrile, methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; glycol-based acrylate monomers such as (meth)acrylic acid polyethylene glycol, (meth)acrylic acid polypropylene glycol, (meth)acrylic acid methoxyethylene glycol, (meth)acrylic acid methoxypolypropylene glycol; acrylate monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, 2-methoxyethyl acrylate, etc. can also be used. Furthermore, isoprene, butadiene, isobutylene, vinyl ether, etc. can be mentioned.

[0058] Furthermore, as copolymerizable monomers other than those described above, silane-based monomers containing silicon atoms, etc. can be mentioned. Examples of silane-based monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc.

[0059] Furthermore, as the copolymerization monomer, (meth)acrylic acid esters such as tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6 - hexanediol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone - modified dipentaerythritol hexa(meth)acrylate, which are esters of (meth)acrylic acid and polyhydric alcohols, and polyfunctional monomers having two or more unsaturated double bonds such as (meth)acryloyl groups and vinyl groups, and polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, etc., in which two or more unsaturated double bonds such as (meth)acryloyl groups and vinyl groups are added as functional groups similar to the monomer components to the skeletons of polyester, epoxy, urethane, etc. can also be used.

[0060] (Meth)acrylic polymers are mainly composed of alkyl (meth)acrylates in terms of the weight ratio of all constituent monomers, and the ratio is preferably 70% to 99.9% by weight, more preferably 75% to 99% by weight, and even more preferably 80% to 98% by weight. By using alkyl (meth)acrylates as the main component, an adhesive excellent in adhesive properties can be obtained.

[0061] The weight ratio of the copolymerization monomer in all constituent monomers is preferably 0.1% to 30% by weight, more preferably 1% to 25% by weight, and even more preferably 2% to 30% by weight in terms of the weight ratio of all constituent monomers.

[0062] Among these copolymer monomers, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferably used from the viewpoints of adhesiveness and durability. The hydroxyl group-containing monomer and the carboxyl group-containing monomer can be used in combination. These copolymer monomers serve as reaction points with a crosslinking agent when the pressure-sensitive adhesive contains a crosslinking agent. Hydroxyl group-containing monomers, carboxyl group-containing monomers, etc. are highly reactive with intermolecular crosslinking agents, and are thus preferably used to improve the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer.

[0063] When the copolymer monomer contains a hydroxyl group-containing monomer, the proportion is preferably 0.01% by weight to 15% by weight, more preferably 0.05% by weight to 10% by weight, and even more preferably 0.1% by weight to 5% by weight. When the copolymer monomer contains a carboxyl group-containing monomer, the proportion is preferably 0.01% by weight to 15% by weight, more preferably 0.05% by weight to 10% by weight, and even more preferably 0.1% by weight to 5% by weight.

[0064] The weight average molecular weight of the above (meth)acrylic polymer is, for example, 1 million to 2.5 million, preferably 1.2 million to 2.3 million. When the weight average molecular weight is 1 million or more, it is preferable in terms of heat resistance. Also, when the weight average molecular weight exceeds 2.5 million, the pressure-sensitive adhesive may become hard. The weight average molecular weight is determined from the value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

[0065] For the production of such (meth)acrylic polymers, known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. Also, the resulting (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc.

[0066] In addition, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer can contain a crosslinking agent corresponding to the base polymer. When, for example, a (meth)acrylic polymer is used as the base polymer, an organic crosslinking agent or a polyfunctional metal chelate can be used as the crosslinking agent. Examples of the organic crosslinking agent include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, and the like. The polyfunctional metal chelate is one in which a polyvalent metal is covalently bonded or coordinately bonded to an organic compound. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Examples of the atom in the organic compound that forms a covalent bond or a coordinate bond include an oxygen atom, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, ketone compounds, and the like.

[0067] The amount of the crosslinking agent used is preferably 0.5 to 6 parts by weight, more preferably 1 to 6 parts by weight, still more preferably 2 to 5.5 parts by weight, and even more preferably 3 to 5 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer.

[0068] The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer can contain a silane coupling agent and other additives. For example, polyether compounds of polyalkylene glycols such as polypropylene glycol, powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, reducing agents, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulate materials, foil-like materials, etc. can be appropriately added according to the intended use. These additives are preferably used in an amount of 5 parts by weight or less, more preferably 3 parts by weight or less, and still more preferably 1 part by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer.

[0069] E. Image display device The optical film with the adhesive layer can be applied to image display devices such as organic EL display devices and liquid crystal display devices. Therefore, embodiments of the present invention include image display devices provided with the optical film with the adhesive layer. When the image display device is an organic EL display device, the optical film with the adhesive layer is laminated on the viewing side of the organic EL cell so that the retardation layer is on the organic EL cell side.

Examples

[0070] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods for each property are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. (1) Thickness For a thickness of 10 μm or less, it was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). For a thickness exceeding 10 μm, it was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). (2) Stress-strain measurement The adhesive solution was cast and coated on the release-treated surface of a polyethylene terephthalate film (thickness: 38 μm) that had been release-treated on one side so that the thickness after drying was about 4 μm. After heating and drying at 130 °C for 3 minutes and further aging at 50 °C for 24 hours, a sample formed into a columnar shape with a cross-sectional area of 1 mm 2 was used as a sample. This sample was placed on a tensile testing machine (manufactured by Shimadzu Corporation, Shimadzu Autograph AG-IS MS type), and the maximum stress (N / mm 2 ) and the maximum elongation (%) generated when pulled under the conditions of a chuck distance of 10 mm, a pulling speed of 300 mm / min, and 25 °C were measured. (3) Moisture permeability A sample in which a retardation layer (a laminate of a first retardation layer and a second retardation layer) was bonded to a TAC film with a thickness of 25 μm via an adhesive was used as a measurement sample and measured in accordance with JIS Z 0208 (cup method). (4) Creep value The pressure-sensitive adhesive layer - attached optical film was cut into a size of 10 mm × 30 mm to obtain a test sample. The upper end portion (10 mm × 10 mm) of the test sample was adhered to a SUS plate via the pressure-sensitive adhesive layer, and autoclave treatment was performed under the conditions of 50°C and 5 atm for 15 minutes. A precision hot plate installed such that the heating surface was in the vertical direction was heated to 85°C, and the SUS plate with the pressure-sensitive adhesive layer - attached optical film was installed such that the surface without the pressure-sensitive adhesive layer adhered thereto was in contact with the heating surface of the hot plate. After heating the SUS plate at 85°C for 5 minutes, a load of 500 gf was vertically applied downward to the lower end portion of the polarizing film with the pressure-sensitive adhesive layer. The amount of displacement between the pressure-sensitive adhesive layer - attached optical film and the SUS plate 1 second and 3600 seconds after applying the load was measured, and designated as Cr1 and Cr 3600 respectively. Cr1 and Cr 3600 The ΔCr obtained from the following formula using Cr1 and Cr ΔCr = Cr 3600 - Cr1 (5) Storage modulus The release film was peeled off from the pressure-sensitive adhesive layer prepared in the production example, and a plurality of pressure-sensitive adhesive layers were laminated to prepare a test sample with a thickness of about 1.5 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and dynamic viscoelasticity measurement was performed under the following conditions using "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific, and the storage modulus G' was read from the measurement results. (Measurement conditions) Deformation mode: torsion Measurement temperature: -40°C to 150°C Temperature rising rate: 5°C / min Measurement frequency: 1 Hz (6) Transmittance of single layer Regarding a polarizing plate having a configuration of [polarizer / protective layer], the transmittance Ts in the wavelength range of 380 nm to 780 nm when measured using an ultraviolet - visible - near - infrared spectrophotometer (V - 7100 manufactured by JASCO Corporation) was defined as the transmittance Ts of the single layer of the polarizer. This Ts is the Y value measured by the 2° field of view (C light source) of JIS Z8701 and subjected to visual sensitivity correction.

[0071] [Production Example 1: Preparation of Adhesive Layer A] 1. Preparation of Adhesive Into a reaction vessel equipped with a cooling pipe, a nitrogen inlet pipe, a thermometer, and a stirring device, 94.9 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and 0.3 part of 2,2'-azobisisobutyronitrile were added together with ethyl acetate to prepare a solution. Then, while blowing nitrogen gas into this solution and stirring, the reaction was carried out at 55°C for 8 hours to obtain a solution containing an acrylic polymer with a weight average molecular weight of 2.1 million. Further, ethyl acetate was added to the solution containing this acrylic polymer to obtain an acrylic polymer solution with a solid content concentration adjusted to 30%.

[0072] Based on 100 parts of the solid content of the acrylic polymer solution, 4 parts of a crosslinking agent mainly composed of a compound having isocyanate groups (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") and 0.2 part of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") were blended in this order to prepare an adhesive solution.

[0073] 2. Preparation of Adhesive Layer The above adhesive solution was applied and dried on the surface of a release film made of a polyethylene terephthalate film (thickness 38 μm) subjected to a release treatment so that the thickness after drying was 20 μm to prepare an adhesive layer A.

[0074] [Production Example 2: Preparation of Adhesive Layer B] An adhesive layer B was prepared in the same manner as in Production Example 1, except that the addition amount of the crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") was 0.6 part and the adhesive solution was applied so that the thickness after drying was 15 μm.

[0075] [Production Example 3: Preparation of Adhesive Layer C] As a monomer component, a solution containing an acrylic polymer with a weight average molecular weight of 1.8 million was obtained using 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate. As a crosslinking agent, 0.1 part of trimethylolpropane / xylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Takenate D110N") and 0.3 part of peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") were used. And an adhesive layer C was prepared in the same manner as in Production Example 1 except that the adhesive solution was applied so that the thickness after drying was 15 μm.

[0076] [Production Example 4: Preparation of Adhesive Layer D] As a monomer component, a solution containing an acrylic polymer with a weight average molecular weight of 1.8 million was obtained using 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate. As a crosslinking agent, 0.02 part of trimethylolpropane / xylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Takenate D110N") and 0.3 part of peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") were used. And an adhesive layer D was prepared in the same manner as in Production Example 1 except that the adhesive solution was applied so that the thickness after drying was 21 μm.

[0077] [Production Example 5: Preparation of Adhesive Layer E] An adhesive layer E (thickness 30 μm) was obtained in the same manner as in Production Example 3 except that the adhesive solution was applied so that the thickness of the resulting adhesive layer was 30 μm.

[0078] Viscoelasticity measurement was performed using the adhesive layers A to D prepared in Production Examples 1 to 4. Also, the creep value of the adhesive layer was evaluated using an optical film with an adhesive layer provided with the adhesive layers A to D (the optical film with an adhesive layer obtained in Examples 1 to 4 below). The results are shown in Table 1.

[0079]

Table 1

[0080] [Example 1] 1. Production of Polarizer As the thermoplastic resin substrate, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) in a long strip shape with a water absorption rate of 0.75% and a Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") at a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilization bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment). Next, the laminate was immersed in a dyeing bath at a liquid temperature of 30°C (an iodine aqueous solution prepared by mixing iodine and potassium iodide so that the iodine concentration is 0.03% by weight and the potassium concentration is 0.2% by weight) for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizing film is 42.0% (dyeing treatment). Next, the laminate was immersed in a cross-linking bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (cross-linking treatment). Thereafter, while immersing the laminate in an aqueous boric acid solution at a liquid temperature of 70°C (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight), uniaxial stretching was performed in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds so that the total stretching ratio is 5.5 times (in-water stretching treatment). Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a SUS heating roll having a surface temperature maintained at 75°C for about 2 seconds (drying and shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying and shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

[0081] 2. Production of polarizing plate An HC-TAC film was laminated on the surface of the polarizer of the [resin substrate / polarizer] laminate obtained above through a PVA-based resin aqueous solution. Specifically, a PVA-based resin aqueous solution (manufactured by Nippon Gosei Chemical Industry Co., Ltd., trade name "Gosefilm (registered trademark) Z-200", resin concentration: 3% by weight) was applied, the HC-TAC film was laminated, and it was heated in an oven maintained at 60°C for 5 minutes for lamination. The HC-TAC film is a film in which a hard coat (HC) layer (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film was laminated so as to be on the polarizer side. Next, the resin substrate was peeled off to obtain a polarizing plate having a configuration of [outer protective layer (HC-TAC film) / polarizer].

[0082] 3. Production of the first retardation layer 55 parts of the compound represented by formula (I), 25 parts of the compound represented by formula (II), and 20 parts of the compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN). After that, the mixture was heated to 60 °C and stirred until dissolved. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 part of Megafac F-554 (manufactured by DIC Corporation), and 0.1 part of p-methoxyphenol (MEHQ) were added, followed by further stirring to obtain a solution. The solution was transparent and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, a polyimide solution for an alignment film was applied to a glass substrate with a thickness of 0.7 mm using a spin coating method, dried at 100 °C for 10 minutes, and then fired at 200 °C for 60 minutes to obtain a coating film. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing apparatus. The polymerizable composition obtained above was applied to the substrate (substantially the alignment film) by a spin coating method and dried at 100 °C for 2 minutes. After the obtained coating film was cooled to room temperature, it was irradiated with ultraviolet rays at an intensity of 30 mW / cm 2 for 30 seconds using a high-pressure mercury lamp to obtain a liquid crystal alignment cured layer (thickness: 2.8 μm). The in-plane retardation Re(550) of the liquid crystal alignment cured layer was 130 nm. Also, Re(450) / Re(550) of the liquid crystal alignment cured layer was 0.851, showing an inverse dispersion wavelength characteristic.

[0083]

Chemical formula

Chemical formula

[0084] 4. Preparation of the second retardation layer 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (IV) (the numbers 65 and 35 in the formula represent mol% of monomer units and are represented as a block polymer for convenience: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal showing a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating solution. Then, the coating solution was applied to a substrate film (norbornene-based resin film: manufactured by Nippon Zeon Co., Ltd., trade name "Zeonex") using a bar coater, and then heated and dried at 80°C for 4 minutes to align the liquid crystal. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby forming an alignment and curing layer (liquid crystal alignment and curing layer, thickness 0.58 μm) of a liquid crystal compound that becomes a second retardation layer on the substrate. The Re(590) of this layer was 0 nm, and the Rth(590) was -100 nm, showing a refractive index characteristic of nz > nx = ny. [Chemical formula]

[0085] 5. Preparation of an optical film with an adhesive layer The first retardation layer was bonded to the polarizer surface of the polarizing plate obtained in 2. through an adhesive (thickness 5 μm), and the glass substrate was peeled off. Here, it was bonded so that the angle between the absorption axis of the polarizer and the slow axis of the first retardation layer was +45°. Next, the second retardation layer was bonded to the surface of the first retardation layer through a UV-curable adhesive (thickness 1 μm), and the substrate film was peeled off. Further, the adhesive layer A prepared in Production Example 1 was bonded to the surface of the second retardation layer. Thereby, an optical film with an adhesive layer (substantially a circular polarizing plate with an adhesive layer) having a structure of [protective layer / polarizer / first retardation layer / second retardation layer / adhesive layer A ( / release film)] was obtained.

[0086] [Example 2] An optical film with an adhesive layer having a structure of [protective layer / polarizer / first retardation layer / second retardation layer / adhesive layer B ( / release film)] was obtained in the same manner as in Example 1, except that adhesive layer B was used instead of adhesive layer A.

[0087] [Comparative Example 1] An optical film with an adhesive layer having a structure of [protective layer / polarizer / first retardation layer / second retardation layer / adhesive layer C ( / release film)] was obtained in the same manner as in Example 1, except that adhesive layer C was used instead of adhesive layer A.

[0088] [Comparative Example 2] An optical film with an adhesive layer having a structure of [protective layer / polarizer / first retardation layer / second retardation layer / adhesive layer D ( / release film)] was obtained in the same manner as in Example 1, except that adhesive layer D was used instead of adhesive layer A.

[0089] [Comparative Example 3] An optical film with an adhesive layer having a structure of [protective layer / polarizer / first retardation layer / second retardation layer / adhesive layer E ( / release film)] was obtained in the same manner as in Example 1, except that adhesive layer E was used instead of adhesive layer A.

[0090] [Reference Example 1] 1. Preparation of Polarizer A polarizer with a thickness of 5 μm was formed on a resin substrate in the same manner as in Example 1, except that the iodine concentration in the dyeing bath was 0.025% by weight and the potassium concentration was 0.18% by weight.

[0091] 2. Preparation of Polarizing Plate A polarizing plate having a structure of [outer protective layer (HC-TAC film) / polarizer] was obtained in the same manner as in Example 1, except that the laminate of [resin substrate / polarizer] obtained above was used.

[0092] 3. Preparation of Retardation Film Constituting the Retardation Layer 3-1. Polymerization of Polyester Carbonate Resin Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100 °C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluorene-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 -2 parts by mass (6.78×10 -5 mol) of calcium acetate monohydrate as a catalyst were charged. After replacing the inside of the reactor with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the internal temperature reached 100 °C. The internal temperature reached 220 °C 40 minutes after the start of temperature increase, and while controlling to maintain this temperature, reduced pressure was started and it was made 13.3 kPa in 90 minutes after reaching 220 °C. The phenol vapor by-produced along with the polymerization reaction was led to a reflux condenser at 100 °C, the monomer components contained in a small amount in the phenol vapor were returned to the reactor, and the phenol vapor that did not condense was led to a condenser at 45 °C and recovered. Nitrogen was introduced into the first reactor to repressurize to atmospheric pressure once, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and reduced pressure in the second reactor were started, and the internal temperature was made 240 °C and the pressure was made 0.2 kPa in 50 minutes. Thereafter, the polymerization was allowed to proceed until a predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, and the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.

[0093] 3-2. Preparation of the retardation film 0.7 parts by mass of PMMA was melt-kneaded into the obtained polyester carbonate resin (pellets), and after vacuum drying at 80 °C for 5 hours, a film forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 °C), a T-die (width 200 mm, set temperature: 250 °C), a chill roll (set temperature: 120 - 130 °C), and a winder was used to produce a long resin film with a thickness of 130 μm. The obtained long resin film was stretched while adjusting so as to obtain a predetermined retardation, and a retardation film with a thickness of 38 μm was obtained. The stretching conditions were a stretching temperature of 143 °C and a stretching ratio of 2.8 times in the width direction. Re(550) of the obtained retardation film was 141 nm, Re(450) / Re(550) was 0.86, and the Nz coefficient was 1.12.

[0094] 4. Production of an optical film with an adhesive layer A retardation film was laminated on the polarizer surface of the polarizing plate obtained in 2. through an adhesive (thickness 5 μm). Here, it was laminated so that the angle between the absorption axis of the polarizer and the slow axis of the retardation film was +45°. Next, the adhesive layer E produced in Production Example 5 was transferred onto the surface of the retardation film. Thereby, an optical film with an adhesive layer having a structure of [protective layer / polarizer / retardation layer / adhesive layer E ( / release film)] was obtained.

[0095] 〈Cutting process〉 Using a laminate in which a surface protective film (manufactured by Nitto Denko Corporation, product name "PPF-100T") was laminated on the HC-attached TAC film side of the optical film with an adhesive layer obtained in the examples, comparative examples, and reference examples as the workpiece, the end faces of each of the four sides of the rectangle were cut and polished by 2.5 mm with a full-back cutter under the following conditions, and cut into a rectangular shape with a size of 25 mm × 50 mm. [Processing conditions] Rotation speed / feed rate: 4500 rpm / 900 mm / min

[0096] The obtained optical film with an adhesive layer in a rectangular shape was cut in the thickness direction, and the cross-section was observed at a magnification of 10 times using an optical microscope (MX61L, manufactured by Olympus Corporation), and the horizontal distance (amount of glue shortage) between the position P2 at the end of the adhesive layer and the position P1 at the end of the polarizer was measured. The results are shown in Table 2.

[0097] 〈Hot water test〉 The release film was peeled off from the obtained optical film with an adhesive layer in a rectangular shape by cutting, and the adhesive layer was exposed. The optical film with an adhesive layer was bonded to a glass plate through the adhesive layer and immersed in hot water at 60°C for 30 minutes. The optical film with an adhesive layer after immersion was observed with a microscope, and the depth (amount of discoloration) of the region where discoloration occurred was measured with reference to the end of the polarizer. Also, considering the practical allowable range of the amount of discoloration, when the amount of discoloration was 250 μm or less, it was evaluated as "good", and when it exceeded 250 μm, it was evaluated as "bad". The results are shown in Table 2.

[0098]

Table 2

[0099] As shown in Table 2, in the reference example where the moisture permeability of the retardation layer was low, even if the amount of glue shortage was large, the discoloration of the polarizer was within the practical allowable range. However, in the comparative example where the moisture permeability of the retardation layer was high and the amount of glue shortage was also large, the amount of discoloration of the polarizer was large. On the other hand, in the example where the amount of glue shortage was small, even if the moisture permeability of the retardation layer was high, the discoloration of the polarizer was suppressed within the practical allowable range.

Industrial applicability

[0100] The optical film with an adhesive layer of the present invention is suitably used as a circular polarizing plate for image display devices such as liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

Explanation of symbols

[0101] 10 Polarizing plate 11 Polarizing film 12 Outer protective layer 13 Inner protective layer 20 Retardation layer 30 Adhesive layer 100 Optical film with adhesive layer

Claims

1. A polarizing plate including a polarizer and a protective layer disposed only on the viewing side of the polarizer, a retardation layer, and an adhesive layer, provided in this order from the viewing side. The moisture permeability of the retardation layer is 300 g / m ２ ·24 h or more, and The thickness of the retardation layer is from 1 μm to 10 μm. When stress-strain measurement is performed on the adhesive layer at 23°C, the strain amount at a stress of 0.4 N is from 200% to 400%. An optical film with an adhesive layer, in cross-sectional view, the end of the adhesive layer is located inward of the end of the polarizer, and the horizontal distance between the end of the adhesive layer and the end of the polarizer is from 0 μm to 50 μm.

2. The optical film with an adhesive layer according to Claim 1, wherein the thickness of the polarizer is 10 μm or less.

3. The retardation layer includes an alignment cured layer of a liquid crystal compound. Re(550) and Re(450) of the alignment cured layer of the liquid crystal compound satisfy the relationship of 0.8 ≤ Re(450) / Re(550) < 1. Re(550) of the alignment cured layer of the liquid crystal compound is from 100 nm to 190 nm. The optical film with an adhesive layer according to Claim 1 or 2, wherein the angle formed by the slow axis of the alignment cured layer of the liquid crystal compound and the absorption axis of the polarizer is from 40° to 50°.

4. An image display device including the optical film with an adhesive layer according to any one of Claims 1 to 3.

5. The image display device according to Claim 4, which is an organic electroluminescence display device.

Images