Polarizing plate with a phase difference layer

Abstract

To provide polarizing plates with retardation layers, which are less susceptible to cracking when bent in a low-temperature environment.SOLUTION: A polarizing plate with a retardation layer of the present invention comprises a protective layer, a polarizer, a retardation layer, and an adhesive layer arranged in the described order, where a total thickness from the protective layer to the retardation layer is 80 μm or less and the adhesive layer has a storage modulus G'-30 of 250 kPa or less at -30°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polarizing plate with a retardation layer.

Background Art

[0002] In recent years, image display devices typified by liquid crystal display devices and organic EL display devices have been rapidly spreading. Typically, a polarizing plate and a retardation plate are used in image display devices. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1). In recent years, foldable image display devices typified by smartphones have been put on the market, and the polarizing plate with a retardation layer used in such image display devices is required to have bending resistance. However, in conventional polarizing plates with a retardation layer, the bending resistance under harsh environments is insufficient, and there are problems such as cracks occurring when folded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer in which the generation of cracks is suppressed under low-temperature environments.

Means for Solving the Problems

[0005] The polarizing plate with a retardation layer of the present invention includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order, the total thickness from the protective layer to the retardation layer is 80 μm or less, and the storage elastic modulus G' of the adhesive layer at -30°C -30is 250 kPa or less. In one embodiment, the storage elastic modulus G' of the pressure-sensitive adhesive layer at -30°C -30 and the storage elastic modulus G' of the pressure-sensitive adhesive layer at 25°C 25 satisfy the following formula (1). 1 ≤ G' -30 / G' 25 ≤ 10...(1) In one embodiment, the storage elastic modulus G' of the pressure-sensitive adhesive layer at -30°C -30 is 200 kPa or less. In one embodiment, the pressure-sensitive adhesive layer is composed of an acrylic pressure-sensitive adhesive containing an acrylic-based polymer. In one embodiment, the acrylic-based polymer contains 1 to 40 parts by weight of a C-chain alkyl ester of (meth)acrylic acid 10-20 per 100 parts by weight of the total monomer components. In one embodiment, the acrylic-based polymer contains lauryl acrylate as the C-chain alkyl ester of (meth)acrylic acid. 10-20 In one embodiment, the acrylic-based polymer contains 5 to 30 parts by weight of one or more polar group-containing monomers selected from monomers having a nitrogen atom-containing ring, hydroxy group-containing monomers, and carboxy group-containing monomers per 100 parts by weight of the total monomer components. In one embodiment, the acrylic-based polymer contains 10 parts by weight or less of a hydroxy group-containing monomer per 100 parts by weight of the total monomer components. In one embodiment, the total thickness from the protective layer to the retardation layer is 60 μm or less. In one embodiment, the thickness of the polarizer is 10 μm or less. In one embodiment, the thickness of the protective layer is 45 μm or less. In one embodiment, the retardation layer has a laminated structure of a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer. The Re(550) of the first liquid crystal alignment cured layer is 200 nm to 300 nm, and the angle formed by its slow axis and the absorption axis of the polarizer is 10° to 20°. The Re(550) of the second liquid crystal alignment cured layer is 100 nm to 190 nm, and the angle formed by its slow axis and the absorption axis of the polarizer is 70° to 80°. In one embodiment, the retardation layer is a single layer of a liquid crystal alignment cured layer. The Re(550) of the retardation layer is 100 nm to 180 nm, and satisfies the relationship of Re(450) < Re(550) < Re(650). The angle formed by its slow axis and the absorption axis of the polarizer is 35° to 55°. Further, in one embodiment, the retardation layer further includes another retardation layer, and the another retardation layer exhibits a refractive index characteristic of nz > nx = ny.

Advantages of the Invention

[0006] According to an embodiment of the present invention, a polarizing plate with a retardation layer includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order. The total thickness from the protective layer to the retardation layer is 80 μm or less, and the storage elastic modulus G' of the adhesive layer at -30°C -30 is 250 kPa or less, thereby realizing a polarizing plate with a retardation layer in which the generation of cracks during bending is suppressed in a low-temperature environment.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] (Definition 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 where 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 Phase Difference (Re) “Re(λ)” is the in-plane phase difference measured with light of wavelength λ nm at 23°C. For example, “Re(550)” is the in-plane phase difference measured with light of wavelength 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Phase Difference 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. Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (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°.

[0010] A. Overall Configuration of Polarizing Plate with Phase Difference Layer The polarizing plate with a retardation layer of the present invention has a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order. FIG. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example has a protective layer 10, a polarizer 20, a retardation layer 30, and an adhesive layer 40 in this order. As shown in FIG. 1, the retardation layer 30 may be composed of a first liquid crystal alignment cured layer 31 and a second liquid crystal alignment cured layer 32. Alternatively, as shown in FIG. 2, the retardation layer 30 is a single layer of a liquid crystal alignment cured layer, and another retardation layer 33 may be provided between the retardation layer 30 and the adhesive layer 40. In an embodiment of the present invention, the retardation layer 30 is typically provided directly on the polarizer 20 (that is, without intervening other layers other than the adhesive layer).

[0011] In an embodiment of the present invention, in the above polarizing plate with a retardation layer, the total thickness from the protective layer to the retardation layer is 80 μm or less, and the storage elastic modulus G' of the adhesive layer at -30°C -30 is 250 kPa or less. By configuring the total thickness from the protective layer to the retardation layer to be within the above range and further defining the storage elastic modulus of the adhesive layer at -30°C as described above, it is possible to realize a polarizing plate with a retardation layer in which the generation of cracks during bending is suppressed in a low-temperature environment. In a conventional adhesive provided on a polarizing plate with a retardation layer, the storage elastic modulus in a low-temperature environment (for example, -30°C) becomes higher and may harden compared to the storage elastic modulus in a normal-temperature environment (for example, 25°C). Due to this phenomenon, in a conventional polarizing plate with a retardation layer, there is a problem that the desired bending resistance cannot be obtained in a harsh environment (especially in a low-temperature environment). In the present invention, it has been found that by using an adhesive whose storage elastic modulus is below a certain value even in a low-temperature environment, the hardening of the adhesive is suppressed and the bending resistance of the polarizing plate with a retardation layer is maintained. Furthermore, by defining the ratio of the storage elastic modulus of the above adhesive at -30°C to the storage elastic modulus at 25°C within a specific range, the desired storage elastic modulus is satisfied and the bending resistance of the polarizing plate with a retardation layer can be maintained in a wide temperature range including not only a low-temperature environment but also a normal-temperature environment.

[0012] The retardation film - attached polarizing plate has a total thickness from the protective layer to the retardation film of 80 μm or less, preferably 70 μm or less, and more preferably 60 μm or less as described above. The lower limit of the total thickness from the protective layer to the retardation film can be, for example, 20 μm. By having the total thickness from the protective layer to the retardation film within such a range, a retardation film - attached polarizing plate with suppressed crack generation during bending in a low - temperature environment can be obtained.

[0013] The retardation film - attached polarizing plate 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 retardation film - attached polarizing plate can be appropriately set according to the purpose. For example, the retardation film - attached polarizing plate may further have a conductive layer or an anisotropic substrate with a conductive layer (both not shown). The conductive layer or the anisotropic substrate with a conductive layer is typically provided on the side opposite to the polarizer 20 of the retardation layer 30. When the conductive layer or the anisotropic substrate with a conductive layer is provided, the retardation film - attached polarizing plate can be applied to a so - called inner - touch - panel - type input display device in which a touch sensor is incorporated between an organic EL cell and the polarizing plate.

[0014] The retardation film - attached polarizing plate may be in a sheet form or a long - strip form. In this specification, "long - strip form" means an elongated shape in which the length is sufficiently long relative to the width, for example, including an elongated shape in which the length is 10 times or more, preferably 20 times or more, the width. The long - strip retardation film - attached polarizing plate can be wound into a roll.

[0015] It is preferable that a release film is temporarily adhered to the surface of the adhesive layer 40 until the retardation film - attached polarizing plate is put into use. By temporarily adhering the release film, the adhesive layer is protected and the roll formation of the retardation film - attached polarizing plate becomes possible.

[0016] Hereinafter, the components of the retardation film - attached polarizing plate will be described in more detail.

[0017] B. Polarizing Plate Hereinafter, the components of the polarizing plate will be described in more detail.

[0018] B-1. Polarizer As the polarizer, any appropriate polarizer can be adopted. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0019] Specific examples of the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, which are dyed and stretched with dichroic substances such as iodine and dichroic dyes, 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 film with iodine and uniaxially stretching it is used because of its excellent optical properties.

[0020] The above-mentioned dyeing with iodine is performed, for example, by immersing the PVA-based 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, during the dyeing, or after the stretching and then the dyeing. If necessary, the PVA-based film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can the dirt on the surface of the PVA-based film and the blocking inhibitor be washed, but also the PVA-based film can be swollen to prevent uneven dyeing.

[0021] Specific examples of the polarizer obtained using the laminate 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 formed by coating on the resin substrate. The polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it 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; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. 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 substrate / polarizer may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the laminate of the resin substrate / 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 Japanese Patent Application Laid-Open No. 2012-73580 (Patent No. 5414738) and Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

[0022] The thickness of the polarizer is preferably 10 μm or less, more preferably 8 μm or less, and still more preferably 6 μm or less. The lower limit of the thickness of the polarizer can be, for example, 1 μm. If the thickness of the polarizer is within such a range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained. Further, if the thickness of the polarizer is within such a range, the above-described desired total thickness can be achieved.

[0023] The polarizer preferably exhibits absorption dichroism at any wavelength in the 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 more 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.

[0024] B-2. Protective layer The above protective layer is formed of any suitable film. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, acetate-based, and other transparent resins. Also, thermosetting resins or ultraviolet curable resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, and silicone-based resins can be mentioned. In addition, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Also, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the above resin composition.

[0025] The polarizing plate with a retardation layer according to an embodiment of the present invention is typically disposed on the viewing side of an organic EL display device, and the protective layer 10 is disposed on its viewing side. Therefore, the protective layer 10 may be subjected to surface treatments such as hard coat treatment, antireflection treatment, anti-sticking treatment, and antiglare treatment, if necessary.

[0026] The thickness of the protective layer is preferably 45 μm or less, more preferably 40 μm, and even more preferably 35 μm or less. The lower limit of the thickness of the protective layer can be, for example, 10 μm. When surface treatment is performed, the thickness of the protective layer 10 is the thickness including the thickness of the surface treatment layer.

[0027] C. Retardation layer In one embodiment, the retardation layer 30 has a laminated structure of a first liquid crystal alignment cured layer 31 and a second liquid crystal alignment cured layer 32 as described in C-1. In another embodiment, as described in C-2, the retardation layer 30 is a single layer of a liquid crystal alignment cured layer, and still another retardation layer 33 is provided between the retardation layer 30 and the adhesive layer 40.

[0028] C-1. Retardation layer having a laminated structure of a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer C-1-1. First liquid crystal alignment cured layer The first liquid crystal alignment cured layer 31 can function as a so-called λ / 2 plate. By using the first liquid crystal alignment cured layer as a so-called λ / 2 plate and the second liquid crystal alignment cured layer described below as a so-called λ / 4 plate and setting their slow axes in a predetermined direction with respect to the absorption axis of the polarizer, an optical laminate having excellent circular polarization characteristics in a wide band can be obtained. The in-plane retardation Re(550) of the first liquid crystal alignment cured layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, and even more preferably 250 nm to 280 nm.

[0029] The refractive index ellipsoid of the first liquid crystal alignment cured layer typically exhibits a relationship of nx > ny = nz. The angle formed between the slow axis of the first liquid crystal alignment cured layer 31 and the absorption axis of the polarizer 20 is preferably 10° to 20°, more preferably 13° to 17°, and even more preferably about 15°, as described above. If the angle formed between the slow axis of the first liquid crystal alignment cured layer and the absorption axis of the polarizer is within such a range, the in-plane retardations of the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer can be set within predetermined ranges respectively, and by arranging the slow axis of the second liquid crystal alignment cured layer at a predetermined angle with respect to the absorption axis of the polarizer as described later, an optical laminate having extremely excellent circular polarization characteristics (and as a result, extremely excellent antireflection characteristics) in a wide band can be obtained.

[0030] The thickness of the first liquid crystal alignment cured layer is preferably 1 μm to 7 μm, and more preferably 1.5 μm to 2.5 μm. As described above, by using a liquid crystal compound, the difference between nx and ny of the obtained optical compensation layer can be made significantly larger than that of a non-liquid crystal material, so that the layer thickness required to obtain a desired in-plane retardation can be significantly reduced. Therefore, an in-plane retardation equivalent to that of a resin film can be realized with a thickness significantly thinner than that of a resin film.

[0031] The first liquid crystal alignment cured layer is typically oriented with rod-shaped liquid crystal compounds aligned in a predetermined direction (homogeneous alignment). The slow axis can be developed in the alignment direction of the liquid crystal compounds. Examples of the liquid crystal compounds include liquid crystal compounds having a nematic liquid crystal phase (nematic liquid crystals). As such liquid crystal compounds, for example, liquid crystal polymers and liquid crystal monomers can be used. The mechanism for the manifestation of liquid crystallinity of the liquid crystal compounds can be either lyotropic or thermotropic. The liquid crystal polymers and liquid crystal monomers can be used alone or in combination.

[0032] When the liquid crystal compound is a liquid crystal monomer, it is preferable that the liquid crystal monomer is a polymerizable monomer and a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After the liquid crystal monomer is aligned, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the alignment state can be fixed thereby. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the formed first liquid crystal alignment solidified layer, for example, a transition from a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to the liquid crystalline compound does not occur. As a result, the first liquid crystal alignment solidified layer becomes a layer that is not affected by temperature changes and has extremely excellent stability.

[0033] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably from 40°C to 120°C, more preferably from 50°C to 100°C, and most preferably from 60°C to 90°C.

[0034] As the above liquid crystal monomer, any suitable liquid crystal monomer can be employed. For example, polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445, etc. can be used. Specific examples of such polymerizable mesogenic compounds include, for example, LC242 with the trade name of BASF, E7 with the trade name of Merck, and LC-Sillicon-CC3767 with the trade name of Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

[0035] The first liquid crystal alignment curing layer can be formed by subjecting the surface of a predetermined substrate to an alignment treatment, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. By using such an alignment treatment, the liquid crystal compound can be aligned in a predetermined direction with respect to the longitudinal direction of the long substrate, and as a result, a slow axis can be expressed in a predetermined direction of the formed liquid crystal alignment curing layer. For example, a liquid crystal alignment curing layer having a slow axis in a direction of 15° with respect to the longitudinal direction can be formed on a long substrate. Such a liquid crystal alignment curing layer can be laminated using roll-to-roll even when it is desired to have a slow axis in an oblique direction, so that the productivity of the optical laminate can be significantly improved. In one embodiment, the substrate is any suitable resin film, and the alignment curing layer formed on the substrate can be transferred to the surface of the polarizer. In another embodiment, the substrate can be an inner protective layer (inner protective film). In this case, the transfer step is omitted, and lamination can be continuously performed by roll-to-roll from the formation of the alignment curing layer.

[0036] As the alignment treatment, any suitable alignment treatment can be adopted. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique evaporation method and photoalignment treatment. The treatment conditions of various alignment treatments can be any suitable conditions according to the purpose.

[0037] The alignment of the liquid crystal compound is performed by treating at a temperature at which the liquid crystal compound exhibits a liquid crystal phase according to the type of the liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound takes a liquid crystal state and aligns according to the alignment treatment direction of the substrate surface.

[0038] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0039] Specific examples of the liquid crystal compound and details of the method for forming the alignment fixing layer are described in JP-A-2006-163343. The description of this publication is incorporated herein by reference.

[0040] C-1-2. Second Liquid Crystal Alignment Fixing Layer The second liquid crystal alignment fixing layer 32 can function as a so-called λ / 4 plate. By using the second liquid crystal alignment fixing layer as a so-called λ / 4 plate, the first liquid crystal alignment fixing layer as a so-called λ / 2 plate as described above, and setting their slow axes in a predetermined direction with respect to the absorption axis of the polarizer, an optical laminate having excellent circular polarization characteristics in a wide band can be obtained. The in-plane retardation Re(550) of the second liquid crystal alignment fixing layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and still more preferably 130 nm to 150 nm as described above.

[0041] The refractive index ellipsoid of the second liquid crystal alignment fixing layer typically shows a relationship of nx > ny = nz. The angle formed by the slow axis of the second liquid crystal alignment fixing layer 32 and the absorption axis of the polarizer 20 is preferably 65° to 85°, more preferably 72° to 78°, and still more preferably about 75° as described above. If the angle formed by the slow axis of the second liquid crystal alignment fixing layer and the absorption axis of the polarizer is within such a range, the in-plane retardations of the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer are set in respective predetermined ranges, and the slow axis of the first liquid crystal alignment fixing layer is arranged at a predetermined angle as described above with respect to the absorption axis of the polarizer, whereby an optical laminate having very excellent circular polarization characteristics (and as a result, very excellent antireflection characteristics) in a wide band can be obtained.

[0042] The thickness of the second liquid crystal alignment cured layer is preferably 0.5 μm to 2 μm, more preferably 1 μm to 1.5 μm.

[0043] The constituent materials, properties, manufacturing methods, etc. of the second liquid crystal alignment cured layer are as described in the above item C-1-1 with respect to the first liquid crystal alignment cured layer.

[0044] Regarding the embodiment in which the angle formed by the slow axis of the first liquid crystal alignment cured layer 31 and the absorption axis of the polarizer 20 is about 15°, and the angle formed by the slow axis of the second liquid crystal alignment cured layer 32 and the absorption axis of the polarizer 20 is about 75°, the relationship of this axis angle may be reversed. Specifically, the angle formed by the slow axis of the first liquid crystal alignment cured layer 31 and the absorption axis of the polarizer 20 may preferably be 65° to 85°, more preferably 72° to 78°, and even more preferably about 75°; in this case, the angle formed by the slow axis of the second liquid crystal alignment cured layer 32 and the absorption axis of the polarizer 20 may preferably be 10° to 20°, more preferably 13° to 17°, and even more preferably about 15°. Also, the first liquid crystal alignment cured layer 31 may be a λ / 4 plate, and the second liquid crystal alignment cured layer 32 may be a λ / 2 plate.

[0045] C-2. A retardation layer composed of a single layer of a liquid crystal alignment layer and another retardation layer C-2-1. A single layer of a liquid crystal alignment cured layer In another embodiment, the retardation layer 30 is a single layer of a liquid crystal compound alignment cured layer. The retardation layer can typically function as a λ / 4 plate. The retardation layer typically exhibits a refractive index characteristic of nx > ny = nz. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 160 nm, and even more preferably 120 nm to 140 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 the range not impairing the effects of the present invention, ny > nz or ny < nz may occur.

[0046] The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3.

[0047] 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, the retardation layer satisfies the relationship Re(450) < Re(550) < Re(650), and 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.

[0048] The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 35° to 55°, more preferably 40° to 50°, still more preferably 42° to 48°, and particularly preferably about 45°. If the angle is in such a range, an organic EL display device having very excellent antireflection characteristics can be obtained by using the retardation layer as a λ / 4 plate as described above.

[0049] The retardation layer can be composed of any appropriate material as long as it can satisfy the above characteristics. Specifically, the retardation layer may be a stretched film of a resin film.

[0050] Typical examples of the resin constituting the resin film include polycarbonate resins or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins). As the polycarbonate resin, any suitable polycarbonate resin can be used as long as the desired moisture permeability can be obtained. For example, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from an alicyclic dimethanol and / or a structural unit derived from di-, tri- or polyethylene glycol; more preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri- or polyethylene glycol. The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. The retardation layer can be formed by stretching a film made of the polycarbonate resin as described above under any suitable stretching conditions. Details of the polycarbonate resin and the method for forming the retardation layer are described, for example, in JP-A-2014-10291, JP-A-2014-26266 (Patent No. 5528606), JP-A-2015-212816 (Patent No. 6189355), JP-A-2015-212817 (Patent No. 6823899), JP-A-2015-212818, JP-A-2017-54093 (Patent No. 6360821), and JP-A-2018-60014 (Patent No. 6321107). The descriptions of these publications are incorporated herein by reference.

[0051] The thickness of the retardation layer can typically be set to a thickness that can function appropriately as a λ / 4 plate.

[0052] C-2-2. Another retardation layer In another embodiment of the present invention, the polarizing plate with a retardation layer may further include another retardation layer 33 between the retardation layer 30 and the adhesive layer 40. The another retardation layer may preferably be a so-called positive C-plate showing a refractive index characteristic of nz > nx = ny. By using a positive C-plate as the another retardation layer, reflection in an oblique direction can be prevented well, 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 another 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 another retardation layer can be less than 10 nm.

[0053] The another retardation layer having a refractive index characteristic of nz > nx = ny can be formed of any suitable material. The another 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 liquid crystal alignment curing layer include the liquid crystal compounds and the method for forming the liquid crystal alignment curing layer described in

[0020] to

[0028] of JP-A-2002-333642 (Patent No. 4174192). In this case, the thickness of the another 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.

[0054] D. Adhesive layer In the polarizing plate with a retardation layer according to the embodiment of the present invention, the storage elastic modulus G' of the adhesive layer at -30°C -30 is 250 kPa or less, preferably 200 kPa or less. The storage elastic modulus G' of the adhesive layer -30The lower limit can be, for example, 100 kPa. Also, the storage elastic modulus G' of the adhesive layer at 25°C -25 is 100 kPa or less, preferably 50 kPa or less. The lower limit of the storage elastic modulus G' of the adhesive layer -25 can be, for example, 10 kPa. Further, preferably, the above G' -30 and G' 25 satisfy the following formula (1). 1 ≦ G' -30 / G' 25 ≦ 10…(1) The above G' -30 and G' 25 more preferably satisfy 2 ≦ G' -30 / G' 25 ≦ 9, and even more preferably satisfy 3 ≦ G' -30 / G' 25 ≦ 8. In the retardation film - attached polarizing plate according to the embodiment of the present invention, since the adhesive layer has such a storage elastic modulus, the generation of cracks during bending in a low - temperature environment is suppressed.

[0055] The thickness of the adhesive layer is preferably 10 μm to 100 μm, more preferably 20 μm to 60 μm.

[0056] The adhesive for forming the adhesive layer contains at least a base polymer. The base polymer is an adhesive component that exhibits adhesiveness in the adhesive layer 40. Examples of the base polymer include acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate / vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluorine polymers, and rubber polymers. The base polymer may be used alone or in combination of two or more. From the viewpoint of ensuring good transparency and adhesiveness in the adhesive layer 40, an acrylic polymer is preferably used as the base polymer.

[0057] The acrylic polymer is a copolymer of a monomer component containing an alkyl (meth)acrylate at a ratio of 50% by mass or more. "Alkyl (meth)acrylate" means acrylic acid and / or methacrylic acid.

[0058] As the alkyl (meth)acrylate, an alkyl (meth)acrylate preferably having 1 to 20 carbon atoms in the alkyl group is preferably used, and more preferably an alkyl (meth)acrylate having 10 to 20 carbon atoms in the alkyl group is preferably used. The alkyl (meth)acrylate may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.

[0059] Examples of the alkyl (meth)acrylate having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (i.e., lauryl acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

[0060] Examples of the alkyl (meth)acrylate having an alicyclic alkyl group include cycloalkyl (meth)acrylates, (meth)acrylates having a bicyclic aliphatic hydrocarbon ring, and (meth)acrylates having a tricyclic or higher aliphatic hydrocarbon ring. Examples of the cycloalkyl (meth)acrylate include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of the (meth)acrylate having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. Examples of the (meth)acrylate having a tricyclic or higher aliphatic hydrocarbon ring include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0061] As the alkyl (meth)acrylate, an alkyl acrylate having an alkyl group with 3 to 15 carbon atoms is preferably used, and more preferably, at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and dodecyl acrylate (i.e., lauryl acrylate) is used.

[0062] From the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer, the proportion of the alkyl (meth)acrylate in the monomer component is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. The proportion is, for example, 99% by mass or less.

[0063] With respect to 100 parts by weight in total of the monomer components of the acrylic-based polymer, C of (meth)acrylic acid 10-20The amount of the chain-like alkyl ester is preferably from 1 part by weight to 40 parts by weight, more preferably from 5 parts by weight to 35 parts by weight. In particular, it is preferable that the amount of lauryl acrylate is within the above range.

[0064] The monomer component may contain a copolymerizable monomer copolymerizable with an alkyl (meth)acrylate. Examples of the copolymerizable monomer include monomers having a polar group. Examples of the polar group-containing monomer include monomers having a nitrogen atom-containing ring, hydroxy group-containing monomers, and carboxy group-containing monomers. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing crosslinking points into the acrylic polymer and ensuring the cohesive force of the acrylic polymer.

[0065] Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyl oxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. As the monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

[0066] From the viewpoints of ensuring the cohesive force in the pressure-sensitive adhesive layer and ensuring the adhesion strength to the adherend in the pressure-sensitive adhesive layer, the proportion of the monomer having a nitrogen atom-containing ring in the monomer component is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.55% by mass or more. From the viewpoints of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the pressure-sensitive adhesive layer and the acrylic polymer), the proportion is preferably 10% by mass or less, more preferably 5% by mass or less.

[0067] Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (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 (meth)acrylate. As the hydroxy group-containing monomer, preferably 4-hydroxybutyl (meth)acrylate is used, and more preferably 4-hydroxybutyl acrylate is used.

[0068] From the viewpoints of introducing a crosslinked structure into the acrylic polymer and ensuring the cohesive force in the pressure-sensitive adhesive layer, the proportion of the hydroxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 0.8% by mass or more. From the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the pressure-sensitive adhesive layer 40 and the acrylic polymer), the proportion is preferably 10% by mass or less, more preferably 8% by mass or less.

[0069] Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0070] The proportion of the carboxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 0.8% by mass or more, from the viewpoints of introducing a crosslinked structure into the acrylic polymer, ensuring the cohesive force in the pressure-sensitive adhesive layer 40, and ensuring the adhesion to the adherend in the pressure-sensitive adhesive layer 40. The proportion is preferably 30% by mass or less, more preferably 25% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by an acid.

[0071] The amount of the polar group-containing monomer with respect to 100 parts by weight in total of the monomer components of the acrylic-based polymer is preferably 5 parts by weight or more, and may be 6 parts by weight or more, 7 parts by weight or more, or 8 parts by weight or more. On the other hand, as the content of the polar monomer increases, the dipole moment of the base polymer increases and the relative dielectric constant increases. Further, if the content of the polar monomer is excessively large, the glass transition temperature of the polymer becomes high and the adhesive strength at low temperature tends to decrease. Therefore, the amount of the polar group-containing monomer with respect to 100 parts by weight in total of the monomer components of the acrylic-based polymer is preferably 30 parts by weight or less, and may be 25 parts by weight or less.

[0072] The monomer component may contain other copolymerizable monomers. Examples of the other copolymerizable monomers include an acid anhydride monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, an epoxy group-containing monomer, a cyano group-containing monomer, an alkoxy group-containing monomer, and an aromatic vinyl compound. These other copolymerizable monomers may be used alone or in combination of two or more.

[0073] In this embodiment, the base polymer has a crosslinked structure. As a method for introducing a crosslinked structure into the base polymer, a method of blending a base polymer having a functional group capable of reacting with a crosslinking agent and the crosslinking agent in the pressure-sensitive adhesive composition and reacting the base polymer and the crosslinking agent in the pressure-sensitive adhesive layer 40, and a method of including a polyfunctional monomer in the monomer components forming the base polymer and forming a base polymer in which a branched structure (crosslinked structure) is introduced into the polymer chain by polymerization of the monomer components can be mentioned. These methods may be used in combination.

[0074] The acrylic polymer can be formed by polymerizing monomer components. Examples of the polymerization method include solution polymerization, active energy ray polymerization (e.g., UV polymerization), bulk polymerization, and emulsion polymerization. From the viewpoints of the transparency, water resistance, and cost of the pressure-sensitive adhesive layer 40, solution polymerization and UV polymerization are preferable. As the solvent for solution polymerization, for example, ethyl acetate and toluene are used. Further, as the polymerization initiator, for example, a thermal polymerization initiator and a photoinitiator are used. The usage amount of the polymerization initiator is, for example, 0.05 parts by weight or more and, for example, 1 part by weight or less with respect to 100 parts by weight of the monomer components.

[0075] From the viewpoint of ensuring the cohesive force in the pressure-sensitive adhesive layer 40, the weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and still more preferably 500,000 or more. The same weight average molecular weight is preferably 5,000,000 or less, more preferably 3,000,000 or less, and still more preferably 2,000,000 or less. The weight average molecular weight of the acrylic polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene conversion.

[0076] The glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and still more preferably -20°C or lower. The same glass transition temperature is, for example, -80°C or higher.

[0077] The pressure-sensitive adhesive composition may contain one or more kinds of oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, preferably, an acrylic oligomer is used as the oligomer. The acrylic oligomer is a copolymer of a monomer component containing an alkyl (meth)acrylate in a proportion of 50% by mass or more, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.

[0078] Examples of the crosslinking agent include compounds that react with functional groups (such as hydroxy groups and carboxy groups) contained in the base polymer. Examples of such crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. The crosslinking agent may be used alone or two or more kinds may be used in combination. As the crosslinking agent, isocyanate crosslinking agents, peroxide crosslinking agents, and epoxy crosslinking agents are preferably used because they have high reactivity with hydroxy groups and carboxy groups in the base polymer and it is easy to introduce a crosslinked structure.

[0079] The pressure-sensitive adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, based on 100 parts by weight of the base polymer. The content is preferably 5 parts by weight or less, more preferably 3 parts by weight or less.

[0080] The pressure-sensitive adhesive composition may contain other components as necessary. Examples of the other components include tackifiers, plasticizers, softening agents, deterioration inhibitors, fillers, colorants, ultraviolet absorbers, antioxidants, surfactants, and antistatic agents.

Examples

[0081] 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) Flexural resistance From the polarizing plates with a retardation layer obtained in the examples and comparative examples, a sample of 100 mm × 30 mm was cut out as a measurement sample and measured using a bending tester (manufactured by Yuasa System Devices Co., Ltd., product name "CL09 Type D01"). The measurement temperature was -30°C or 25°C. The bending diameter φ = 3 mm, the number of bending cycles was 500,000 times, and the bending direction was inward bending, and the measurement was carried out and evaluated according to the following criteria. Good: No cracks occurred after the 500,000 - cycle bending test Poor: Cracks occurred after the 500,000 - cycle bending test

[0082] [Production Example 1] Preparation of Adhesive Layer A 1. Preparation of acrylic - based polymer In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, a mixture containing 70 parts by weight of 2 - ethylhexyl acrylate (2EHA), 20 parts by weight of n - butyl acrylate (BA), 8 parts by weight of lauryl acrylate (LA), 1 part by weight of 4 - hydroxybutyl acrylate (4HBA), 0.6 part by weight of N - vinyl - 2 - pyrrolidone (NVP), 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as a solvent (solid content concentration 47 mass%) was stirred at 56°C for 6 hours under a nitrogen atmosphere (polymerization reaction). As a result, a polymer solution containing an acrylic - based polymer was obtained. The weight - average molecular weight of the acrylic - based polymer in this polymer solution was about 2 million. 2. Preparation of adhesive composition To the polymer solution, 1.5 parts by weight of a first acrylic oligomer, 0.26 parts by weight of a first crosslinking agent (trade name "Niper BMT-40SV", dibenzoyl peroxide, manufactured by NOF Corporation), 0.02 parts by weight of a second crosslinking agent (trade name "Coronate L", trimethylolpropane / toluene diisocyanate trimer adduct, manufactured by Tosoh Corporation), and 0.3 parts by weight of a silane coupling agent (trade name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added per 100 parts by weight of the solid content of the polymer solution, and the mixture was stirred to prepare an adhesive composition. 3. Formation of Adhesive Layer A The adhesive composition A was applied onto the release-treated surface of a first release film having one side silicone-release-treated to form a coating film. The first release film is a polyethylene terephthalate (PET) film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having one side silicone-release-treated. Next, the release-treated surface of a second release film having one side silicone-release-treated was laminated onto the coating film on the first release film. The second release film is a PET film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having one side silicone-release-treated. Next, the coating film on the first release film was dried by heating at 100°C for 1 minute and then at 150°C for 3 minutes to form a transparent adhesive layer A having a thickness of 50 μm. The thickness of the obtained adhesive layer A was 50 μm.

[0083] [Production Example 2] Preparation of Adhesive Layer B 1. Preparation of Acrylic Base Polymer A mixture containing 56 parts by weight of 2-ethylhexyl acrylate (2EHA), 34 parts by weight of lauryl acrylate (LA), 7 parts by weight of 4-hydroxybutyl acrylate (4HBA), 2 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by weight of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins) was irradiated with ultraviolet rays (polymerization reaction) to obtain a prepolymer composition (the polymerization rate was approximately 10%) (the prepolymer composition contains monomer components that have not undergone the polymerization reaction). 2. Preparation of Adhesive Composition Next, 100 parts by weight of the prepolymer composition, 0.08 parts by weight of 1,6 - hexanediol diacrylate (HDDA), 1 part by weight of the second acrylic oligomer, and 0.3 parts by weight of a silane coupling agent (trade name "KBM403", manufactured by Shin - Etsu Chemical Co., Ltd.) were mixed to prepare a photocurable pressure - sensitive adhesive composition. 3. Formation of the pressure - sensitive adhesive layer B The pressure - sensitive adhesive composition B was applied onto the release - treated surface of the first release film with one - side silicone release treatment to form a coating film. The first release film is a polyethylene terephthalate (PET) film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) with one - side silicone release treatment. Next, the release - treated surface of the second release film with one - side silicone release treatment was laminated onto the coating film on the first release film. The second release film is a PET film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) with one - side silicone release treatment. Next, the coating film was irradiated with ultraviolet rays through the second release film to cure the coating film by ultraviolet rays. A black light was used for the ultraviolet ray irradiation. The irradiation intensity of the ultraviolet rays was 5 mW / cm 2 The thickness of the obtained pressure - sensitive adhesive layer B was 50 μm.

[0084] [Production Example 3] Preparation of the pressure - sensitive adhesive layer C 1. Preparation of the acrylic - based polymer A mixture containing 44 parts by weight of 2 - ethylhexyl acrylate (2EHA), 43 parts by weight of lauryl acrylate (LA), 6 parts by weight of 4 - hydroxybutyl acrylate (4HBA), 7 parts by weight of N - vinyl - 2 - pyrrolidone (NVP), and 0.015 parts by weight of a photoinitiator (trade name "Omnirad 184", manufactured by IGM Resins) was irradiated with ultraviolet rays (polymerization reaction) to obtain a prepolymer composition (the polymerization rate was about 10%) (the prepolymer composition contains monomer components that have not undergone the polymerization reaction). 2. Preparation of the pressure - sensitive adhesive composition Next, 100 parts by weight of the prepolymer composition, 0.08 parts by weight of 1,6 - hexanediol diacrylate (HDDA), 1 part by weight of the second acrylic oligomer, and 0.3 parts by weight of a silane coupling agent (trade name "KBM403", manufactured by Shin - Etsu Chemical Co., Ltd.) were mixed to prepare a photocurable pressure - sensitive adhesive composition. 3. Formation of the pressure - sensitive adhesive layer C The pressure - sensitive adhesive composition C was applied onto the release - treated surface of the first release film with one - side silicone release treatment to form a coating film. The first release film is a polyethylene terephthalate (PET) film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) with one - side silicone release treatment. Next, the release - treated surface of the second release film with one - side silicone release treatment was laminated onto the coating film on the first release film. The second release film is a PET film (trade name "Diafoil MRF#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) with one - side silicone release treatment. Next, the coating film was irradiated with ultraviolet rays through the second release film to cure the coating film by ultraviolet rays. A black light was used for the ultraviolet irradiation. The irradiation intensity of the ultraviolet rays was 5 mW / cm 2 and the thickness of the obtained pressure - sensitive adhesive layer C was 25 μm.

[0085] [Production Example 4] Preparation of the pressure - sensitive adhesive layer D 1. Preparation of the acrylic polymer A monomer mixture containing 94.9 parts by weight of butyl acrylate (BA), 0.1 parts by weight of 2 - hydroxyethyl acrylate (HEA), and 5 parts by weight of acrylic acid (AA) was charged into a four - necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler. Further, 0.2 parts by weight of 2,2´ - azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate with respect to 100 parts by weight of the above monomer mixture (solid content). After introducing nitrogen gas while gently stirring for nitrogen substitution, the liquid temperature in the flask was maintained at around 55 °C and a polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the obtained reaction solution to prepare an acrylic polymer solution with a solid content concentration of 30% and a weight - average molecular weight of 2.2 million. 2. Preparation of the pressure - sensitive adhesive composition To 100 parts by weight of the solid content of the obtained acrylic polymer solution, 0.6 part by weight of trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") as a crosslinking agent and 0.2 part by weight of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added and stirred to obtain an adhesive composition. 3. Formation of Adhesive Layer D The above acrylic adhesive composition was uniformly coated on the surface of a release film made of a 38-μm-thick polyethylene terephthalate film (PET film, transparent base material) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form an adhesive layer D with a thickness of 50 μm.

[0086] [Production Example 5] Preparation of Adhesive Layer E 1. Preparation of Acrylic Polymer A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. Further, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator was charged together with ethyl acetate with respect to 100 parts by weight of the monomer mixture, and nitrogen gas was introduced while gently stirring for nitrogen substitution. Then, the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55°C. Thereafter, ethyl acetate was added to the obtained reaction solution to prepare an acrylic polymer solution having a solid content concentration of 30% and a weight average molecular weight of 1.8 million. 2. Preparation of Adhesive Composition To 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 part of trimethylolpropane / xylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Takenate D110N") and 0.3 part of a peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") were blended in this order to obtain an adhesive composition. 3. Formation of Adhesive Layer E The above acrylic pressure-sensitive adhesive composition was uniformly coated on the surface of a release film made of a 38-μm-thick polyethylene terephthalate film (PET film, transparent base material) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulation constant-temperature oven at 155°C for 2 minutes to form an adhesive layer E with a thickness of 50 μm.

[0087] [Example 1] 1. Preparation of Polarizer As a thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) that is long, has a water absorption rate of 0.75%, and a Tg of about 75°C was used. One side of the resin base material was subjected to corona treatment. 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 base material 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 freely at a ratio of 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 with a liquid temperature of 40°C (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment). Next, the laminate was immersed in a dyeing bath with a liquid temperature of 30°C (an aqueous iodine solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer is 43.0% or more (dyeing treatment). Next, the laminate was immersed in a crosslinking bath with a liquid temperature of 40°C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (crosslinking treatment). Thereafter, while immersing the laminate in an aqueous boric acid solution (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, uniaxial stretching was performed in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds so that the total draw ratio became 5.5 times (stretching treatment in water). Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a SUS-made heating roll whose surface temperature was maintained at 75°C for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the dry shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm was formed on the resin base material.

[0088] 2. Production of polarizing plate An acrylic resin film (thickness: 20 μm) was bonded to the surface of the polarizer obtained above via a PVA-based adhesive. In this way, a polarizing plate having a structure of acrylic resin film / adhesive / polarizer was obtained.

[0089] 3. Production of first liquid crystal alignment curing layer and second liquid crystal alignment curing layer 10 g of a polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) showing a nematic liquid crystal phase and 3 g of a photopolymerization initiator (manufactured by BASF: trade name "Irgacure 907") for the polymerizable liquid crystal compound were dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

Chemical formula

[0090] 4. Fabrication of Polarizer with Retardation Layer The first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer obtained in 3. above were transferred in this order onto the surface of the polarizer of the polarizer obtained in 2. above. At this time, the transfer (lamination) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the first liquid crystal alignment cured layer was 15°, and the angle between the absorption axis of the polarizer and the slow axis of the second liquid crystal alignment cured layer was 75°. Each transfer (lamination) was performed via an ultraviolet curable adhesive (thickness 1.0 μm). Next, the adhesive layer A (thickness 50 μm) obtained in Production Example 1 was disposed on the surface of the second liquid crystal alignment cured layer. In this way, a polarizer with a retardation layer having a configuration of acrylic resin film / adhesive / polarizer / first liquid crystal alignment cured layer / second liquid crystal alignment cured layer / adhesive layer A was obtained. The obtained polarizer with a retardation layer was subjected to the evaluation in (2) above. The results are shown in Table 1.

[0091] [Example 2] A polarizer with a retardation layer was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was 25 μm. The obtained polarizer with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0092] [Example 3] The polarizing plate was produced according to the following procedure 1, and a single layer of the liquid crystal alignment cured layer and another retardation layer were produced according to the following 2 and 3 instead of the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer in Example 1. A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except for this. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0093] 1. Production of the polarizing plate An HC-TAC film was bonded to the surface of the polarizer obtained in 1. of Example 1 via an ultraviolet curable adhesive. Specifically, it was coated so that the thickness of the curable adhesive became 1.0 μm and bonded using a roll machine. Then, UV light was irradiated from the HC-TAC film side to cure the adhesive. 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). In this way, a polarizing plate having a configuration of HC-TAC film / polarizer was obtained.

[0094] 2. Production of a single layer of the liquid crystal alignment cured 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, stirred and dissolved. After dissolution was confirmed, it 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, and stirring was further carried out 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. 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 carried out 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 for 30 seconds at an intensity of 30 mW / cm 2 to obtain a first liquid crystal alignment cured layer. The in-plane retardation Re(550) of the first 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.

[0095]

Chemical formula

Chemical formula

[0096] 3. Preparation of Another Retardation Layer 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (I) (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 the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby forming a second liquid crystal alignment and curing layer (thickness: 0.58 μm) on the substrate. Re(550) of this layer was 0 nm, and Rth(550) was -80 nm, showing a refractive index characteristic of nz > nx = ny.

[0097] [Chemical formula]

[0098] [Example 4] A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the adhesive layer B obtained in Production Example 2 was used. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0099] [Comparative Example 1] A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the adhesive layer D obtained in Production Example 4 was used. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0100] [Comparative Example 2] A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 1, except that the thickness of the adhesive layer was 25 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0101] [Comparative Example 3] A retardation film - attached polarizing plate was obtained in the same manner as in Comparative Example 1, except that the thickness of the adhesive layer was 15 μm. The obtained retardation film - attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0102] [Comparative Example 4] A retardation film - attached polarizing plate was obtained in the same manner as in Example 1, except that the adhesive layer E obtained in Production Example 5 was used. The obtained retardation film - attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0103] [Comparative Example 5] A retardation film - attached polarizing plate was obtained in the same manner as in Example 1, except that the adhesive layer C obtained in Production Example 3 was used and the thickness of the adhesive layer was 25 μm. The obtained retardation film - attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0104] [Comparative Example 6] A retardation film - attached polarizing plate was obtained in the same manner as in Example 3, except that a polarizer formed from a PVA - based resin film (thickness 12 μm) was used for the polarizer and an inner protective layer (TAC film, thickness 25 μm) was provided on the side opposite to the HC - TAC film of the polarizer. The obtained retardation film - attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0105] [Comparative Example 7] A retardation film - attached polarizing plate was obtained in the same manner as in Comparative Example 6, except that the thickness of the adhesive layer was 25 μm. The obtained retardation film - attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0106]

Table 1

[0107] [Evaluation] As is clear from Table 1, according to the examples of the present invention, a retardation layer - attached polarizing plate in which the generation of cracks during bending is suppressed under a low - temperature environment can be obtained. On the other hand, in the retardation layer - attached polarizing plates of the comparative examples, cracks occurred in all of them during the bending test. For example, in Comparative Example 1, cracks occurred along the absorption axis direction of the polarizer, and in Comparative Example 6, cracks occurred along the absorption axis direction of the polarizer and the bending direction of the bending test.

Industrial Applicability

[0108] The retardation layer - attached polarizing plate of the present invention is suitably used for an organic EL display device.

Explanation of Reference Numerals

[0109] 10 Polarizing plate 10 Protective layer 20 Polarizer 30 Retardation layer 31 First liquid crystal alignment curing layer 32 Second liquid crystal alignment curing layer 33 Another retardation layer 40 Adhesive layer 100 Retardation layer - attached polarizing plate 101 Retardation layer - attached polarizing plate

Claims

1. A polarizing plate with a retardation layer, comprising a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order, wherein the total thickness from the protective layer to the retardation layer is 80 μm or less, The storage elastic modulus G' of the adhesive layer at -30°C －３０ is 100 kPa or more and 250 kPa or less, the adhesive layer is composed of an acrylic adhesive containing an acrylic base polymer, The acrylic-based polymer contains 1 to 8 parts by weight of a chain alkyl ester of (meth)acrylic acid with respect to a total of 100 parts by weight of monomer components, １０－２０ and the acrylic base polymer does not contain a (meth)acrylate having an alkoxyalkyl group or an alkylene oxide group as a monomer component, a polarizing plate with a retardation layer.

2. The storage elastic modulus G' of the adhesive layer at -30°C －３０ and the storage elastic modulus G' of the adhesive layer at 25°C ２５ satisfy the following formula (1), the polarizing plate with a retardation layer according to claim 1: 1 ≤ G' －３０ / G' ２５ ≤ 4.6…(1).

3. The storage elastic modulus G' of the pressure-sensitive adhesive layer at -30°C －３０ is 200 kPa or less, and the polarizing plate with a retardation layer according to claim 1 or 2.

4. The acrylic-based polymer contains lauryl acrylate as the (meth)acrylic acid C １０－２０ The retardation film-attached polarizing plate according to any one of claims 1 to 3, wherein the acrylic-based polymer contains lauryl acrylate as the chain alkyl ester.

5. The polarizing plate with a retardation layer according to any one of Claims 1 to 4, wherein the acrylic base polymer contains 5 to 30 parts by weight of one or more polar group-containing monomers selected from monomers having a nitrogen atom-containing ring, hydroxy group-containing monomers, and carboxy group-containing monomers with respect to a total of 100 parts by weight of the monomer components.

6. The polarizing plate with a retardation layer according to any one of Claims 1 to 5, wherein the acrylic base polymer contains 10 parts by weight or less of a hydroxy group-containing monomer with respect to a total of 100 parts by weight of the monomer components.

7. The polarizing plate with a retardation layer according to any one of Claims 1 to 6, wherein the total thickness from the protective layer to the retardation layer is 60 μm or less.

8. The polarizing plate with a retardation layer according to any one of Claims 1 to 7, wherein the thickness of the polarizer is 10 μm or less.

9. The polarizing plate with a retardation layer according to any one of Claims 1 to 8, wherein the thickness of the protective layer is 45 μm or less.

10. The polarizing plate with a retardation layer according to any one of Claims 1 to 9, wherein the retardation layer has a laminated structure of a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer, Re(550) of the first liquid crystal alignment cured layer is 200 nm to 300 nm, the angle formed by its slow axis and the absorption axis of the polarizer is 10° to 20°, Re(550) of the second liquid crystal alignment cured layer is 100 nm to 190 nm, and the angle formed by its slow axis and the absorption axis of the polarizer is 70° to 80°.

11. The polarizing plate with a retardation layer according to any one of Claims 1 to 9, wherein the retardation layer is a single layer of a liquid crystal alignment cured layer, Re(550) of the retardation layer is 100 nm to 180 nm, and the relationship of Re(450) < Re(550) < Re(650) is satisfied, and the angle formed by its slow axis and the absorption axis of the polarizer is 35° to 55°.

12. The polarizing plate with a retardation layer according to claim 11, further comprising another retardation layer, wherein the another retardation layer exhibits a refractive index characteristic of nz > nx = ny.

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