Adhesive-coated optical films and imaging devices including adhesive-coated optical films.

Abstract

The invention relates to a thin optical film that is resistant to fading. The optical film with a pressure-sensitive adhesive layer as described in the invention comprises, in order from the viewer's side, a polarizing plate consisting of a polarizing glass and a protective layer arranged on at least one side of the polarizing glass; a slowing layer; and a pressure-sensitive adhesive layer, wherein the slowing layer has a moisture permeability of 300 g / m2.24 h or more, and wherein, according to the cross-sectional drawing, the end of the pressure-sensitive adhesive layer is arranged inward with respect to the end of the polarizing glass, and the horizontal distance between the end of the pressure-sensitive adhesive layer and the end of the polarizing glass is between 0 µm and 50 µm.

Description

Optical film with pressure-sensitive adhesive layer and image display device including said optical film with pressure-sensitive adhesive layer

[0001] The present invention relates to a pressure-sensitive adhesive layer-attached optical film and an image display device including the pressure-sensitive adhesive layer-attached optical film.

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. Organic EL display devices incorporating an organic EL panel are prone to problems such as reflection of external light and glare of the background because the organic EL panel has a highly reflective metal layer. It is known, therefore, to prevent these problems by providing a circular polarizer including a λ / 4 plate on the viewing side (e.g., Patent Documents 1 to 3).

[0003] By using a λ / 4 plate having reverse wavelength dispersion characteristics as the circular polarizer, excellent anti-reflection characteristics can be realized. On the other hand, from the viewpoint of reducing the thickness of image display devices, there is a demand for reducing the thickness of circular polarizers as well.

[0004] Japanese Patent Application Laid-Open No. 2003-311239 Japanese Patent Application Laid-Open No. 2002-372622 Japanese Patent No. 3325560

[0005] In order to make the circular polarizer thinner, the inventors produced a circular polarizer using a thin λ / 4 plate, but found that the moisture permeability of the λ / 4 plate increased, and as a result, discoloration was more likely to occur at the edges than in conventional circular polarizers.

[0006] The present invention has been made to solve the above problems, and a main object of the present invention is to provide a thin optical film that is inhibited from discoloring.

[0007] Optical films such as circular polarizing plates are usually provided with a pressure-sensitive adhesive layer for bonding to an image display cell. As a result of intensive studies to achieve the above object, the present inventors have found that, when an optical film with a pressure-sensitive adhesive layer is cut into a desired shape, chipping occurs at the edge of the pressure-sensitive adhesive layer, exposing the retardation layer and affecting decolorization of the polarizer. They also came up with the idea that the decolorization can be suppressed by controlling the chipping at the edge of the pressure-sensitive adhesive layer within a predetermined range, and have completed the present invention.

[0008] According to one aspect of the present invention, there is provided a polarizing plate including a polarizer and a protective layer disposed on at least one side of the polarizer, a retardation layer, and a pressure-sensitive adhesive layer in this order from a viewing side, wherein the moisture permeability of the retardation layer is 300 g / m ２ The present invention provides a pressure-sensitive adhesive layer-attached optical film having a shelf life of 24 hours or more, wherein, in a cross-sectional view, an end of the pressure-sensitive adhesive layer is located more inward than an end of the polarizer, and the horizontal distance between the end of the pressure-sensitive 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, the pressure-sensitive adhesive layer exhibits a strain of 900% or less at a stress of 0.4 N when subjected to stress-strain measurement at 23°C. In one embodiment, the retardation layer includes a layer of a liquid crystal compound with a fixed orientation, and the Re(550) and Re(450) of the layer of a liquid crystal compound with a fixed orientation satisfy the relationship 0.8≦Re(450) / Re(550)<1, the Re(550) of the layer of a liquid crystal compound with a fixed orientation is 100 nm to 190 nm, and the angle between the slow axis of the layer of a liquid crystal compound with 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 pressure-sensitive adhesive layer-attached optical film. In one embodiment, the image display device is an organic electroluminescence display device.

[0009] According to the pressure-sensitive adhesive layer-attached optical film of the present invention, exposure of the retardation layer is suppressed, and as a result, discoloration of the polarizer can be suppressed even when a thin retardation layer is used.

[0010] 1 is a schematic cross-sectional view of a pressure-sensitive adhesive layer-attached optical film according to one embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a pressure-sensitive adhesive layer-attached optical film according to another embodiment of the present invention.

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

[0012] (Definition of Terms and Symbols) The definitions of terms and symbols used 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 in-plane direction perpendicular to the slow axis (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 having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Thickness Direction Retardation (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth(λ) = (nx - nz) x d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is calculated by Nz = Rth / Re. (5) Angle When an angle is mentioned in this specification, the angle includes both clockwise and counterclockwise angles relative to the reference direction. Therefore, for example, "45°" means ±45°.

[0013] A. Overall Configuration of Pressure-Sensitive Adhesive Layer-Attached Optical Film FIG. 1 is a schematic cross-sectional view of a pressure-sensitive adhesive layer-attached optical film according to one embodiment of the present invention. The pressure-sensitive adhesive layer-attached optical film 100A shown in the figure has a polarizing plate 10, a retardation layer 20, and a pressure-sensitive 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 the viewing side of the polarizer 11. The protective layer 13 may be omitted depending on the purpose, etc. For example, if the retardation layer 20 can also serve as a protective layer for the polarizer 11, the protective layer 13 may be omitted.

[0014] 2 is a schematic cross-sectional view of a pressure-sensitive adhesive layer-attached optical film according to another embodiment of the present invention. The pressure-sensitive adhesive layer-attached optical film 100B shown in the figure has a polarizing plate 10, a retardation layer 20, and a pressure-sensitive 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 a protective layer for the polarizer 11. A pressure-sensitive adhesive layer-attached optical film omitting the inner protective layer is more likely to cause decoloration of the polarizer when the retardation layer is exposed than a pressure-sensitive adhesive layer-attached optical film having an inner protective layer, and therefore the effects of the present invention can be more suitably obtained.

[0015] In the embodiment of the present invention, the moisture permeability of the retardation layer 20 is 300 g / m ２ - 24h or more, and the end of the pressure-sensitive adhesive layer 30 is located more inward than the end of the polarizer 11 in a cross-sectional view. Here, "located inward" includes being in the same position, and allows the end of the pressure-sensitive adhesive layer 30 to be located on the same vertical line as the end of the polarizer 11 in a cross-sectional view. More specifically, the position of the end of the polarizer 11 in a cross-sectional view is P １ The position of the end of the adhesive layer 30 is P ２ In this case, P １ and P ２ and are on the same vertical line, or P ２ P １ It is located inward from P １ and P ２ The distance (horizontal distance) D between the P １ and P ２ The distance D between the polarizer 11 and the pressure-sensitive adhesive layer 30 is preferably short, and may be 0 μm to 40 μm, 0 μm to 35 μm, 0 μm to 30 μm, or 0 μm to 25 μm. By suppressing exposure of the edge of the retardation layer 20 due to chipping of the pressure-sensitive adhesive layer 30 during cutting, discoloration of the polarizer 11 can be suppressed even when a retardation layer with high moisture permeability is used.

[0016] The retardation layer 20 and the polarizing plate 10 are typically bonded together via an adhesive layer such as an adhesive layer or a pressure-sensitive adhesive layer. In a cross-sectional view, the end of the adhesive layer is preferably located inward from the end of the polarizer. The distance (horizontal distance) between the end of the polarizer and the end of the adhesive layer is preferably short, and may 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 exposure of the polarizing plate due to chipping or the like at the end of the adhesive layer, the effect of suppressing discoloration of the polarizer can be more suitably achieved. 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 be temporarily attached to the surface of the pressure-sensitive adhesive layer until the pressure-sensitive adhesive layer-attached optical film is used. The pressure-sensitive adhesive layer-attached optical film may further include other optical functional layers. The type, characteristics, number, combination, arrangement position, etc. of the optical functional layers that can be provided in the pressure-sensitive adhesive layer-attached optical film can be appropriately set depending on the purpose.

[0018] The total thickness of the pressure-sensitive adhesive layer-attached optical film is preferably 120 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. The lower limit of the total thickness may be, for example, 45 μm. A pressure-sensitive adhesive layer-attached optical film having such a total thickness can contribute to reducing the thickness of an image display device and can have excellent flexibility and bending durability, and therefore can be suitably applied to curved image display devices and / or bendable or foldable image display devices.

[0019] In one embodiment, the pressure-sensitive adhesive layer-attached optical film is a sheet-shaped film cut to a predetermined size. The pressure-sensitive adhesive layer-attached optical film according to an embodiment of the present invention has little chipping of the pressure-sensitive adhesive layer due to shear stress during cutting, so discoloration of the polarizer end portion after being cut into sheets can be suppressed. As the cutting method, any appropriate method can be used, such as punching, milling such as full-back processing, or FFC processing.

[0020] The components of the pressure-sensitive adhesive layer-attached optical film will be described in more detail below.

[0021] B. Polarizing Plate B-1. Polarizer Any appropriate polarizer can be adopted as the polarizer 11. For example, the polarizer may be made of a single-layer resin film, or may be obtained using a laminate of two or more layers.

[0022] Specific examples of polarizers 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 partially saponified ethylene-vinyl acetate copolymer films that have been dyed with iodine or a dichroic substance such as a dichroic dye and stretched, and polyene-based oriented films such as dehydrated PVA and dehydrochlorinated 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 dyeing with iodine is carried out, for example, by immersing the PVA-based resin film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA-based resin film may be stretched and then dyed. If necessary, the PVA-based resin film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based resin film in water and washing it before dyeing, it is possible to wash away dirt and antiblocking agents from the surface of the PVA-based resin film and also to swell the PVA-based resin film, thereby preventing uneven dyeing and the like.

[0024] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further involve in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such a method for producing a polarizer are described in, for example, JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures 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, while the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more.

[0026] The polarizer preferably exhibits absorptive dichroism at any wavelength between 380 nm and 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 even more preferably 99.9% or more.

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

[0028] As described below, the pressure-sensitive adhesive layer-equipped optical film can be placed on the viewing side of an image display device (typically, an organic EL display device) so that the outer protective layer faces the viewing side. Therefore, the outer protective layer may be subjected to surface treatments such as hard coating, anti-reflection, anti-sticking, and anti-glare, as necessary. Furthermore / alternatively, the outer protective layer may be subjected to treatments to improve visibility when viewed through polarized sunglasses (typically, by imparting (elliptically) circular polarization or ultra-high phase difference). By performing such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the pressure-sensitive adhesive layer-equipped optical film can also be suitably applied to image display devices 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. If a surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

[0030] In one embodiment, the inner protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the thickness direction retardation 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 The retardation layer 20 may be a single layer as shown in Fig. 1. 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 (the moisture permeability of the entire laminate in the case of a laminate structure) is, for example, 300 g / m ２ 24 hours or more, for example, 350 g / m ２ ・24h~700g / m ２ When a retardation layer having such humidity is used, the effects of the present invention can be suitably obtained.

[0033] The thickness of the retardation layer (total thickness in the case of a laminated structure) can be appropriately set depending on 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 such a thin retardation layer having high moisture permeability is used, discoloration of the edge 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 the relationship of nx>ny=nz in refractive index characteristics. 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. Note that "ny=nz" here encompasses not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, there may be cases where ny>nz or ny<nz, as long as the effects of the present invention are not impaired.

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

[0036] The retardation layer preferably exhibits a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measuring light. In this case, the 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 this configuration, it is possible to realize very excellent anti-reflection properties.

[0037] The angle between 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°. When the angle is within this range, an organic EL display device having very excellent antireflection properties can be obtained by using a λ / 4 plate as the retardation layer as described above.

[0038] The retardation layer may be made of any suitable material as long as it satisfies the above-mentioned characteristics. Specifically, the retardation layer may be a layer in which a liquid crystal compound is aligned and solidified (hereinafter referred to as a liquid crystal alignment and solidified layer), or a stretched film of a resin film.

[0039] When the retardation layer is a liquid crystal alignment solidified layer, the use of a liquid crystal compound can significantly increase the difference between nx and ny of the resulting retardation layer compared to non-liquid crystal materials, thereby significantly reducing the thickness of the retardation layer required to obtain the desired in-plane retardation. As a result, a pressure-sensitive adhesive layer-attached optical film (and, consequently, the image display device) can be made even thinner. In this specification, the term "alignment solidified layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer and the alignment state is fixed. The term "alignment solidified layer" encompasses an alignment solidified layer obtained by curing a liquid crystal monomer. In this embodiment, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the retardation layer (homogeneous alignment). Specific examples of liquid crystal compounds and details of methods for forming a liquid crystal alignment solidified layer are described, for example, in JP-A-2006-163343 and JP-A-2006-178389. The descriptions in these publications are incorporated herein by reference.

[0040] The thickness of the retardation layer formed of a single layer of the liquid crystal alignment solidified layer can be, for example, 1 μm to 5 μm.

[0041] When the retardation layer 20 has a laminated structure of a first retardation layer 20a and a second retardation layer 20b, the first retardation layer is preferably a single layer that can function as a λ / 4 plate. The angle between the slow axis of the first 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°.

[0042] The second retardation layer may be a so-called positive C plate, whose refractive index characteristics exhibit the relationship nz > nx = ny. By using a positive C plate as the second retardation layer, reflection in oblique directions can be effectively prevented, enabling the anti-reflection function to have a wide viewing angle. In this case, the thickness direction retardation Rth(550) of the second retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even 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 strictly 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 may be less than 10 nm.

[0043] The second retardation layer having refractive index characteristics of nz > nx = ny can be formed of any appropriate material. The second retardation layer is preferably made of a film containing a liquid crystal material fixed in 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 compound and the method for forming the retardation layer described in paragraphs

[0020] to

[0028] of JP-A No. 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, and even more preferably 0.5 μm to 5 μm.

[0044] D. Pressure-sensitive adhesive layer As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer that has relatively high elasticity and that is less susceptible to adhesive chipping due to cutting processing is preferably used.

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

[0046] The creep value of the pressure-sensitive 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 modulus G' of the pressure-sensitive adhesive layer at 25°C is preferably 1.00 x 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 modulus G' of the pressure-sensitive adhesive layer at 85°C is preferably 7.00 x 10 ４ (Pa) or more, more preferably 1.00 × 10 ５ Pa or more, and 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 24h or less, preferably 100g / m ２ ・24h~2000g / m ２ ・It can be 24 hours.

[0050] The thickness of the pressure-sensitive 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 adhesives that form the adhesive layer include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. The adhesive base polymer is selected depending on the type of adhesive. Among adhesives, acrylic-based adhesives are preferably used because of their excellent optical transparency and adhesive properties.

[0052] The acrylic pressure-sensitive adhesive contains a (meth)acrylic polymer as a base polymer. The (meth)acrylic polymer usually contains alkyl (meth)acrylate as a main component as a monomer unit. Note that (meth)acrylate refers to acrylate and / or methacrylate, and (meth) in this specification has the same meaning.

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

[0054] In addition, from the viewpoints of adhesive properties, durability, adjustment of retardation, 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 order to improve adhesiveness and heat resistance, one or more copolymerizable monomers having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, can be introduced into the (meth)acrylic polymer by copolymerization. Specific examples of such copolymerizable monomers include 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; (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and the like. carboxyl group-containing monomers such as 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 phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

[0056] Further, (N-substituted) amide 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 monomers such as aminoethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, and t-butylaminoethyl(meth)acrylate; alkoxyalkyl(meth)acrylate monomers such as methoxyethyl(meth)acrylate and ethoxyethyl(meth)acrylate; N-(meth)acryloyloxymethylene succinimide and N-(meth)acryloyloxymethylene succinimide; p) Examples of copolymerizable monomers include succinimide-based monomers such as 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; and itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

[0057] Other copolymerizable monomers that can be used include vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate. Further examples include isoprene, butadiene, isobutylene, and vinyl ether.

[0058] Further, copolymerizable monomers other than those mentioned above include silicon atom-containing silane-based monomers, etc. Examples of the silane-based monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0059] Furthermore, examples of copolymerizable monomers include 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, and dipentaerythritol tetra(meth)acrylate.

[0043] It is also possible to use polyfunctional monomers having two or more unsaturated double bonds such as (meth)acryloyl groups or vinyl groups, such as esters of (meth)acrylic acid with polyhydric alcohols, such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate; and polyester(meth)acrylates, epoxy(meth)acrylates, urethane(meth)acrylates, etc., in which two or more unsaturated double bonds such as (meth)acryloyl groups or vinyl groups are added as functional groups similar to those of the monomer components to the backbone of polyester, epoxy, urethane, etc.

[0060] The (meth)acrylic polymer preferably contains alkyl(meth)acrylate as a main component, in terms of the weight ratio of all constituent monomers, and the ratio is preferably 70% by weight to 99.9% by weight, more preferably 75% by weight to 99% by weight, and even more preferably 80% by weight to 98% by weight. By using alkyl(meth)acrylate as a main component, a pressure-sensitive adhesive with excellent adhesive properties can be obtained.

[0061] The weight ratio of the copolymerizable monomer to 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.

[0062] Among these copolymerizable monomers, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferably used in terms of adhesiveness and durability. Hydroxyl group-containing monomers and carboxyl group-containing monomers can be used in combination. When the pressure-sensitive adhesive contains a crosslinking agent, these copolymerizable monomers serve as reaction sites with the crosslinking agent. Hydroxyl group-containing monomers, carboxyl group-containing monomers, etc. are highly reactive with intermolecular crosslinking agents, and are therefore preferably used to improve the cohesion and heat resistance of the resulting pressure-sensitive adhesive layer.

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

[0064] The weight-average molecular weight of the (meth)acrylic polymer is, for example, 1,000,000 to 2,500,000, preferably 1,200,000 to 2,300,000. A weight-average molecular weight of 1,000,000 or more is preferable in terms of heat resistance. Furthermore, if the weight-average molecular weight is greater than 2,500,000, the pressure-sensitive adhesive may become hard. The weight-average molecular weight is measured by GPC (gel permeation chromatography) and calculated in polystyrene equivalent terms.

[0065] Such a (meth)acrylic polymer can be produced by appropriately selecting a known production method such as solution polymerization, bulk polymerization, emulsion polymerization, various radical polymerizations, etc. The resulting (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc.

[0066] The adhesive forming the adhesive layer may contain a crosslinking agent appropriate for 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 may be used as the crosslinking agent. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Polyfunctional metal chelates are those in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

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

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

[0069] E. Image display device The pressure-sensitive adhesive layer-attached optical film can be applied to image display devices such as organic EL display devices and liquid crystal display devices. Therefore, an embodiment of the present invention includes an image display device including the pressure-sensitive adhesive layer-attached optical film. When the image display device is an organic EL display device, the pressure-sensitive adhesive layer-attached optical film is laminated on the viewing side of an organic EL cell so that the retardation layer faces the organic EL cell.

[0070] The present invention will be described in detail below with reference to 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 Thicknesses of 10 μm or less were measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). (2) Stress-Strain Measurement A pressure-sensitive adhesive solution was cast onto the release-treated surface of a polyethylene terephthalate film (thickness: 38 μm) with one side treated for release, so that the thickness after drying would be approximately 4 μm. After heating and drying at 130°C for 3 minutes, the film was further aged at 50°C for 24 hours, and then the cross-sectional area of ​​1 mm ２ This sample was placed in a tensile testing machine (Shimadzu Autograph AG-IS MS type, manufactured by Shimadzu Corporation) and stretched at a chuck distance of 10 mm, a tension speed of 300 mm / min, and a temperature of 25°C. The maximum stress (N / mm ２) and maximum elongation (%) were measured. (3) Moisture permeability A sample obtained by bonding a retardation layer (a laminate of a first retardation layer and a second retardation layer) to a 25 μm-thick TAC film via an adhesive was used as a measurement sample, and measurement was performed in accordance with JIS Z 0208 (cup method). (4) Creep value A test sample was prepared by cutting the pressure-sensitive adhesive layer-attached optical film into a size of 10 mm × 30 mm. A 10 mm × 10 mm portion of the upper end of the test sample was attached to an SUS plate via the adhesive layer, and autoclaved for 15 minutes under conditions of 50°C and 5 atmospheres. A precision hot plate installed so that the heating surface was vertical was heated to 85°C, and the SUS plate to which the pressure-sensitive adhesive layer-attached optical film was attached was installed so that the side not attached with the adhesive layer 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 applied vertically downward to the lower end of the pressure-sensitive adhesive layer-attached polarizing film. The amount of displacement between the pressure-sensitive adhesive layer-attached optical film and the SUS plate was measured 1 second and 3600 seconds after the load was applied, and the amount of displacement was measured. １ and Cr ３６００ Cr １ and Cr ３６００ The creep value was determined by the following formula: ΔCr = Cr ３６００ -Cr １(5) Storage Modulus The release film was peeled off from the pressure-sensitive adhesive layer prepared in each Production Example, and a plurality of pressure-sensitive adhesive layers were laminated to prepare a test sample having a thickness of approximately 1.5 mm. This test sample was punched out into a disk having a diameter of 7.9 mm, and sandwiched between parallel plates. Dynamic viscoelasticity measurement was performed under the following conditions using an 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 Heating rate: 5°C / min Measurement frequency: 1 Hz (6) Single transmittance For a polarizing plate having a [polarizer / protective layer] configuration, the transmittance Ts at wavelengths of 380 nm to 780 nm measured using an ultraviolet-visible-near-infrared spectrophotometer (V-7100 manufactured by JASCO Corporation) was taken as the single transmittance Ts of the polarizer. This Ts is the Y value measured using a 2-degree visual field (C light source) according to JIS Z8701 and corrected for visibility.

[0071] [Production Example 1: Preparation of Pressure-Sensitive Adhesive Layer A] 1. Preparation of Pressure-Sensitive Adhesive A solution was prepared by adding 94.9 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 parts of 2-hydroxyethyl acrylate, and 0.3 parts of 2,2'-azobisisobutyronitrile together with ethyl acetate to a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer. This solution was then stirred while blowing in nitrogen gas, and reacted at 55°C for 8 hours to obtain a solution containing an acrylic polymer having a weight-average molecular weight of 2.1 million. Furthermore, ethyl acetate was added to this solution containing the acrylic polymer to adjust the solids concentration to 30%, thereby obtaining an acrylic polymer solution.

[0072] A pressure-sensitive adhesive solution was prepared by blending, in this order, 4 parts of a crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L") whose main component is a compound having an isocyanate group and 0.2 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") per 100 parts of the solid content of the acrylic polymer solution.

[0073] 2. Preparation of Pressure-Sensitive Adhesive Layer The pressure-sensitive adhesive solution was applied to the surface of a release film made of a release-treated polyethylene terephthalate film (thickness: 38 μm) so as to have a dried thickness of 20 μm, and then dried to prepare a pressure-sensitive adhesive layer A.

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

[0075] [Production Example 3: Preparation of adhesive layer C] An adhesive layer C was produced in the same manner as in Production Example 1, except that 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate were used as monomer components to obtain a solution containing an acrylic polymer having a weight average molecular weight of 1,800,000, that 0.1 parts of a trimethylolpropane / xylylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Takenate D110N") and 0.3 parts of a peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") were used as crosslinking agents, and that the adhesive solution was applied so as to have a thickness of 15 μm after drying.

[0076] [Production Example 4: Preparation of adhesive layer D] Adhesive layer D was produced in the same manner as in Production Example 1, except that a solution containing an acrylic polymer having a weight average molecular weight of 1,800,000 was obtained using 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate as monomer components, that 0.02 parts of a trimethylolpropane / xylylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Takenate D110N") and 0.3 parts of a peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") were used as crosslinking agents, and that the adhesive solution was applied so as to have a thickness of 21 μm after drying.

[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 would be 30 μm.

[0078] Viscoelasticity measurements were carried out using the pressure-sensitive adhesive layers A to D produced in Production Examples 1 to 4. In addition, the creep values ​​of the pressure-sensitive adhesive layers were evaluated using pressure-sensitive adhesive layer-attached optical films comprising the pressure-sensitive adhesive layers A to D (pressure-sensitive adhesive layer-attached optical films obtained in Examples 1 to 4 below). The results are shown in Table 1.

[0079]

[0080] Example 1 1. Preparation of Polarizer A long, amorphous, isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of approximately 75°C was used as the thermoplastic resin substrate. One side of the resin substrate was subjected to a corona treatment. A PVA-based resin (a 9:1 mixture of polyvinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIRMER Z410") was prepared by mixing 100 parts by weight of the resin with 13 parts by weight of potassium iodide, and the resulting solution was dissolved in water to prepare an aqueous PVA solution (coating solution). The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a 13 μm-thick PVA-based resin layer, producing a laminate. The resulting laminate was free-end uniaxially stretched 2.4 times in the longitudinal direction (machine direction) between rolls with different peripheral speeds in an oven at 130°C (in-air auxiliary stretching treatment). The laminate was then immersed in an insolubilizing bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment). The laminate was then immersed in a dyeing bath (an iodine aqueous solution containing iodine and potassium iodide blended to an iodine concentration of 0.03 wt% and a potassium concentration of 0.2 wt%) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the final polarizer was 42.0% (dyeing treatment). The laminate was then immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide 5.0 wt%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 (underwater stretching treatment). The laminate was then immersed in a cleaning bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment). Then, while drying in an oven maintained at 90°C, it was brought into contact with a SUS heated roll maintained at a surface temperature of 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.In this manner, a polarizer having a thickness of 5 μm was formed on the resin substrate.

[0081] 2. Preparation of Polarizing Plate An HC-TAC film was bonded to the polarizer surface of the resin substrate / polarizer laminate obtained above via a PVA-based resin aqueous solution. Specifically, a PVA-based resin aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIRMER (registered trademark) Z-200", resin concentration: 3 wt %) was applied, and the HC-TAC film was bonded thereto. The laminate was then heated for 5 minutes in an oven maintained at 60°C. The HC-TAC film was a triacetyl cellulose (TAC) film (thickness: 25 μm) with a hard coat (HC) layer (thickness: 7 μm) formed thereon, and the TAC film was bonded to the polarizer side. The resin substrate was then peeled off to obtain a polarizing plate having a configuration of [outer protective layer (HC-TAC film) / polarizer].

[0082] 3. Preparation of the First Retardation Layer 55 parts of a compound represented by formula (I), 25 parts of a compound represented by formula (II), and 20 parts of a compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN), heated to 60 ° C, stirred to dissolve, and after dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 parts of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added and further stirred to obtain a solution. The solution was transparent and uniform. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. Meanwhile, a polyimide solution for an alignment film was applied to a 0.7 mm thick glass substrate using a spin coating method, dried at 100 ° C for 10 minutes, and then baked 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 carried out using a commercially available rubbing device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating, and dried at 100°C for 2 minutes. After the obtained coating film was cooled to room temperature, it was irradiated with 30 mW / cm using a high-pressure mercury lamp. ２The liquid crystal alignment layer was irradiated with ultraviolet light at an intensity of 1000 nm for 30 seconds to obtain a liquid crystal alignment layer (thickness: 2.8 μm). The in-plane retardation Re(550) of the liquid crystal alignment layer was 130 nm. The Re(450) / Re(550) of the liquid crystal alignment layer was 0.851, and the layer exhibited reverse dispersion wavelength characteristics.

[0083]

[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 indicate the mol% of the monomer unit, and are conveniently expressed as a block polymer: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal (manufactured by BASF: trade name Paliocolor LC242) exhibiting a nematic liquid crystal phase, 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 light and cured to form a liquid crystal compound alignment layer (liquid crystal alignment layer, thickness 0.58 μm) which served as the second retardation layer on the substrate. This layer had Re(590) of 0 nm, Rth(590) of −100 nm, and exhibited refractive index characteristics of nz > nx = ny.

[0085] 5. Preparation of an Optical Film with a Pressure-Sensitive Adhesive Layer A first retardation layer was bonded to the polarizer surface of the polarizing plate obtained in 2. with a pressure-sensitive adhesive (thickness: 5 μm) interposed therebetween, and the glass substrate was peeled off. Here, the layers were bonded so that the angle between the absorption axis of the polarizer and the slow axis of the first retardation layer was +45°. Next, a second retardation layer was bonded to the surface of the first retardation layer with a UV-curable adhesive (thickness: 1 μm), and the substrate film was peeled off. Furthermore, the pressure-sensitive adhesive layer A prepared in Production Example 1 was bonded to the surface of the second retardation layer. This resulted in an optical film with a pressure-sensitive adhesive layer (essentially a circular polarizing plate with a pressure-sensitive adhesive layer) having a configuration of [protective layer / polarizer / first retardation layer / second retardation layer / pressure-sensitive adhesive layer A ( / release film)].

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

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

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

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

[0090] Reference Example 1 1. Preparation of Polarizer A polarizer having 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 dye bath was set to 0.025 wt % and the potassium concentration was set to 0.18 wt %.

[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 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 a stirring blade and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol), and calcium acetate monohydrate 1.19 × 10 as a catalyst. －２ Parts by mass (6.78×10 －５ mol) was charged. After purging the reactor with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was initiated when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was initiated. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and a small amount of monomer components contained in the phenol vapor were returned to the reactor, while uncondensed phenol vapor was introduced into a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor, and the pressure was temporarily restored to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, heating and pressure reduction in the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was achieved. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets.

[0093] 3-2. Preparation of Retardation Film 0.7 parts by mass of PMMA was melt-kneaded with the obtained polyester carbonate resin (pellets) and vacuum-dried at 80 ° C for 5 hours. After that, 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 film-forming device equipped with a winder were used to produce a long resin film with a thickness of 130 μm. The obtained long resin film was stretched while adjusting to obtain a predetermined retardation, and a retardation film with a thickness of 38 μm was obtained. The stretching conditions were a width direction stretching temperature of 143 ° C and a stretch ratio of 2.8 times. The 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. Preparation of Optical Film with Pressure-Sensitive Adhesive Layer A retardation film was attached to the polarizer surface of the polarizing plate obtained in 2. with a pressure-sensitive adhesive (thickness: 5 μm) interposed therebetween. The film was attached so that the angle between the absorption axis of the polarizer and the slow axis of the retardation film was +45°. Next, the pressure-sensitive adhesive layer E prepared in Production Example 5 was transferred to the surface of the retardation film. This resulted in an optical film with a pressure-sensitive adhesive layer having a configuration of [protective layer / polarizer / retardation layer / pressure-sensitive adhesive layer E ( / release film)].

[0095] <Cutting Processing> A laminate in which a surface protective film (manufactured by Nitto Denko, product name "PPF-100T") was laminated on the HC-attached TAC film side of the pressure-sensitive adhesive layer-attached optical film obtained in the Examples, Comparative Examples, and Reference Examples was used as the workpiece, and the end faces of each of the four rectangular sides were cut and polished by 2.5 mm using a full-back cutter under the following conditions to cut into a rectangular shape of 25 mm x 50 mm. [Processing Conditions] Rotational speed / feed rate: 4500 rpm / 900 mm / min

[0096] The obtained rectangular optical film with a pressure-sensitive adhesive layer 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). ２ and the position P of the polarizer end １ The horizontal distance (amount of glue chipping) between the adhesive layer and the adhesive layer was measured. The results are shown in Table 2.

[0097] <Hot Water Test> The release film was peeled off from the rectangular pressure-sensitive adhesive layer-attached optical film obtained by cutting to expose the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer-attached optical film was attached to a glass plate via the pressure-sensitive adhesive layer and immersed in hot water at 60°C for 30 minutes. After immersion, the pressure-sensitive adhesive layer-attached optical film was observed under a microscope, and the depth of the area where discoloration occurred (amount of discoloration) was measured using the edge of the polarizer as the reference. In addition, taking into account the practical allowable range of the amount of discoloration, a discoloration amount of 250 μm or less was evaluated as "good," and a discoloration amount of more than 250 μm was evaluated as "poor." The results are shown in Table 2.

[0098]

[0099] As shown in Table 2, in the Reference Examples in which the moisture permeability of the retardation layer was small, the discoloration of the polarizer was within a practically acceptable range even if the amount of glue chipping was large, but in the Comparative Examples in which the moisture permeability of the retardation layer was large and the amount of glue chipping was also large, the amount of polarizer discoloration was large. On the other hand, in the Examples in which the amount of glue chipping was small, the discoloration of the polarizer was suppressed within a practically acceptable range even if the moisture permeability of the retardation layer was large.

[0100] The pressure-sensitive adhesive layer-attached optical film of the present invention is suitably used as a circular polarizing plate for image displays such as liquid crystal displays, organic EL displays, and inorganic EL displays.

[0101] REFERENCE SIGNS LIST 10 Polarizing plate 11 Polarizer 12 Outer protective layer 13 Inner protective layer 20 Retardation layer 30 Pressure-sensitive adhesive layer 100 Pressure-sensitive adhesive layer-attached optical film

Claims

1. 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, 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, an end portion of the adhesive layer is located inward of an end portion of the polarizer, and a horizontal distance between the end portion of the adhesive layer and the end portion of the polarizer is 0 μm to 50 μm. An optical film with an adhesive layer.

2. The optical film with an adhesive layer according to claim 1, wherein the polarizing plate includes the polarizer and a protective layer disposed only on the viewing side of the polarizer.

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

4. The optical film with an adhesive layer according to any one of claims 1 to 3, wherein the amount of strain at a stress of 0.4 N when measuring stress-strain at 23°C of the adhesive layer is 900% or less.

5. The optical film with an adhesive layer according to any one of claims 1 to 4, wherein the retardation layer includes an alignment and curing layer of a liquid crystal compound, Re(550) and Re(450) of the alignment and curing layer of the liquid crystal compound satisfy the relationship of 0.8 ≦ Re(450) / Re(550) < 1, Re(550) of the alignment and curing layer of the liquid crystal compound is 100 nm to 190 nm, and the angle formed by the slow axis of the alignment and curing layer of the liquid crystal compound and the absorption axis of the polarizer is 40° to 50°.

6. An image display device comprising the optical film with an adhesive layer according to any one of claims 1 to 5.

7. The image display device according to claim 6, which is an organic electroluminescence display device.

Images