The method of producing polarizing plates equipped with a phase shift layer.

Abstract

The invention relates to a method for producing a polarizing plate with a hysteresis layer, prevented from warping, with high productivity. The method for producing a polarizing plate with a hysteresis layer according to a scheme of the invention comprises the following steps: preparation of the layer material comprising a first protective film, a polarizing plate comprising a polarizing layer and a protective layer arranged on at least one side of the polarizing layer, the hysteresis layer, and a second protective film in that order, having a total thickness of the polarizing plate and the thickness of the hysteresis layer less than or equal to 50 µm, and having a ratio of the thickness of the polarizing plate to the thickness of the hysteresis layer greater than or equal to 5; and laying this layer material in an environment with a moisture content greater than or equal to 10.5 g / m³ in a state in which the layer material is laid on a laying surface, so that the layer material is treated with moisture, wherein the laying step is performed in a state in which the principal surface of the layer material is at an angle to the laying surface.

Description

Method for manufacturing a polarizing plate with a retardation layer

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

[0002] 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), are rapidly becoming popular. Image display devices typically use a polarizing plate and a retardation plate. In practice, retardation layer-attached polarizing plates, which integrate a polarizing plate and a retardation plate, are widely used (e.g., Patent Document 1). In recent years, the possibility of bending, flexing, folding, and rolling up image display devices using flexible substrates (e.g., resin substrates) has been investigated. There is a demand for thin retardation layer-attached polarizing plates for use in such image display devices. However, thin retardation layer-attached polarizing plates have a problem in that they are prone to warping.

[0003] Patent No. 3325560

[0004] The present invention has been made to solve the above-mentioned problems of the prior art, and a main object of the present invention is to provide a retardation layer-attached polarizing plate with reduced warpage at a high yield.

[0005] According to an embodiment of the present invention, there is provided a method for producing a polarizing plate with a retardation layer, the method comprising: preparing a laminate having, in this order, a first protective film, a polarizing plate including a polarizer and a protective layer disposed on at least one side of the polarizer, a retardation layer, and a second protective film, wherein the sum of the thickness of the polarizing plate and the thickness of the retardation layer is 50 μm or less, and the ratio of the thickness of the polarizing plate to the thickness of the retardation layer is 5 or more; ３and subjecting the laminate to a humidifying treatment under the above-described environment, wherein the laminate is placed with the main surface of the laminate at an angle to the placement surface. In one embodiment, the manufacturing method includes laminating the polarizing plate and the retardation layer to obtain a laminate precursor. In one embodiment, the manufacturing method includes cutting the laminate precursor into sheets. In one embodiment, the humidifying treatment is performed with a plurality of the laminates arranged side by side. In one embodiment, the moisture permeability of the first protective film at 40°C and 92% RH is 30 g / m ２ In one embodiment, the moisture permeability of the second protective film at 40°C and 92% RH is 30 g / m ２ - 24 hours or less. In one embodiment, the manufacturing method includes laminating the polarizing plate and the retardation layer while transporting them with a roll. In one embodiment, the manufacturing method includes laminating the polarizing plate and the retardation layer using an active energy ray-curable adhesive. In one embodiment, the thickness of the active energy ray-curable adhesive after curing is 0.4 μm or more. In one embodiment, the laminate has a pressure-sensitive adhesive layer arranged on the side of the retardation layer where the polarizing plate is not arranged, and the weight increase per unit area of ​​the laminated portion of the polarizing plate, the retardation layer, and the pressure-sensitive adhesive layer due to the humidification treatment is 0.1% or more. In one embodiment, the time period for the humidification treatment is 6 hours or more. In one embodiment, the amount of water vapor during the humidification treatment is 10.5 g / m ３ ~30g / m ３ In one embodiment, the manufacturing method includes: ３ In one embodiment, the amount of water vapor during the humidification treatment is 0.5 g / m less than the amount of water vapor during lamination of the polarizing plate and the retardation layer. ３ In one embodiment, the moisture permeability of the retardation layer or the protective layer at 40° C. and 92% RH is 300 g / m or more. ２24 hours or more. In one embodiment, a protective layer is arranged on only the side of the polarizer where the retardation layer is not arranged. In one embodiment, the center of gravity in the thickness direction of the polarizer is located closer to the retardation layer than the center of gravity in the thickness direction of the laminated portion of the polarizing plate and the retardation layer. In one embodiment, the retardation layer is an alignment and solidification layer of a liquid crystal compound.

[0006] According to an embodiment of the present invention, by subjecting a laminate having a first protective film, a polarizing plate, a retardation layer, and a second protective film in this order to a humidification treatment under specified conditions, it is possible to produce a retardation layer-attached polarizing plate with reduced warping with good yield, even if the polarizing plate and the retardation layer have a specified thickness.

[0007] Fig. 1 is a schematic cross-sectional view showing the general configuration of a laminate according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing the general configuration of a laminate according to a second embodiment of the present invention. Fig. 3 is a cross-sectional view showing an example of a warped state of a laminate precursor. Fig. 4 is a cross-sectional view showing an example of a laminated portion from a polarizing plate to a pressure-sensitive adhesive layer. Fig. 5 is a cross-sectional view showing an example of a state in which a laminate is placed on a placement surface.

[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 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°.

[0010] A method for manufacturing a polarizing plate with a retardation layer according to one embodiment of the present invention includes preparing a laminate having a polarizing plate including a polarizer and a retardation layer, and placing the laminate on a mounting surface in a predetermined environment.

[0011] A. Laminate FIG. 1 is a schematic cross-sectional view showing the overall configuration of a laminate according to a first embodiment of the present invention. The laminate 100 includes a first protective film 31, a polarizing plate 10, a retardation layer 20, and a second protective film 32, in this order from the viewing side. In the illustrated example, the polarizing plate 10 includes a polarizer 11 and a protective layer 12 disposed on the viewing side of the polarizer 11 (the side on which the retardation layer 20 is not disposed), and no protective layer is disposed between the polarizer 11 and the retardation layer 20. This configuration, for example, can satisfactorily achieve the thickness, total thickness, and thickness ratio of the polarizing plate described below. Typically, the center of gravity in the thickness direction of the polarizer is located closer to the retardation layer than the center of gravity in the thickness direction of the laminated portion between the polarizing plate and the retardation layer.

[0012] Although not shown, a protective layer may be further included on the other side of the polarizer 11 (between the polarizer 11 and the retardation layer 20).

[0013] 2 is a schematic cross-sectional view showing the general configuration of a laminate according to a second embodiment of the present invention. In the first embodiment, the retardation layer 20 is a single layer, whereas in the second embodiment, the retardation layer 20 has a laminated structure including a first retardation layer 21 and a second retardation layer 22. Unlike the illustrated example, the retardation layer 20 may have a laminated structure of three or more layers.

[0014] Although not shown, the laminate may further include other functional layers. The type, characteristics, number, combination, arrangement, etc. of the functional layers that the laminate may include can be appropriately set depending on the purpose. For example, the laminate may further include a conductive layer or an isotropic substrate with a conductive layer. The conductive layer or isotropic substrate with a conductive layer is typically disposed between the retardation layer 20 and the second protective film 32. Note that a laminate (polarizing plate with a retardation layer) having a conductive layer or an isotropic substrate with a conductive layer is applied, for example, to a so-called inner touch panel type input display device in which a touch sensor is incorporated inside an image display panel. As another example, the laminate may further include other retardation layers. The optical properties (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement, etc. of the other retardation layers can be appropriately set depending on the purpose. As a specific example, the viewing side of the polarizer 11 may be provided with another retardation layer (typically, a layer imparting (elliptically) circular polarization function or a layer imparting ultra-high retardation) that improves visibility when viewed through polarized sunglasses. By including such a layer, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the resulting polarizing plate with a retardation layer can be suitably applied to image display devices that can be used outdoors.

[0015] The components constituting the laminate may be laminated via any appropriate adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and a pressure-sensitive adhesive layer. For example, the first protective film 31 is attached to the polarizing plate 10 via a pressure-sensitive adhesive layer. The first protective film 31 may be peeled off before the retardation layer-attached polarizing plate obtained according to the embodiment of the present invention is used (before being laminated on an image display panel) or during the manufacturing process of the final product (image display device), or may be mounted directly on the final product.

[0016] For example, the second protective film 32 is attached to the retardation layer 20 via a pressure-sensitive adhesive layer. In practice, the second protective film 32 can function as a release film (separator) to which the retardation layer-attached polarizing plate obtained according to an embodiment of the present invention is temporarily attached until it is used. By temporarily attaching the release film, for example, the pressure-sensitive adhesive layer is protected and the laminate can be formed into a roll.

[0017] For example, the retardation layer 20 is bonded to the polarizing plate 10 via an adhesive layer (preferably, an active energy ray-curable adhesive). When the retardation layer 20 has a laminated structure of two or more layers, the respective retardation layers are bonded to each other via an adhesive layer (preferably, an active energy ray-curable adhesive).

[0018] A-1. Polarizing Plate The polarizing plate includes a polarizer and a protective layer. The thickness of the polarizing plate, although it depends on the number of protective layers included, is preferably 20 μm or more, more preferably 25 μm or more. On the other hand, the thickness of the polarizing plate is preferably 40 μm or less, more preferably 36 μm or less, and even more preferably 33 μm or less. Note that, if an adhesive layer is used when laminating the polarizer and the protective layer, the thickness of the adhesive layer is not included in the thickness of the polarizing plate.

[0019] The polarizer is typically a resin film containing a dichroic substance (e.g., iodine). Examples of the resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films.

[0020] The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less, while the thickness of the polarizer is preferably 1 μm or more.

[0021] 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 42.0% 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.

[0022] The protective layer may be formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material that serves as the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, and polynorbornene-based cycloolefin-based, polyolefin-based, (meth)acrylic, and acetate-based resins.

[0023] The retardation layer-attached polarizing plate obtained by the embodiment of the present invention is typically placed on the viewing side of an image display device, and the protective layer 12 is placed on the viewing side. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat (HC) treatment, anti-reflection treatment, anti-sticking treatment, anti-glare treatment, etc., as necessary.

[0024] The thickness of the protective layer 12 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 30 μm. If the protective layer 12 has undergone any of the above surface treatments, the thickness of the protective layer 12 includes the thickness of the surface treatment layer.

[0025] In one embodiment, the protective layer (not shown) disposed between the polarizer 11 and the retardation layer 20 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 retardation Rth(550) in the thickness direction is -10 nm to +10 nm. The thickness of the protective layer disposed between the polarizer 11 and the retardation layer 20 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 30 μm.

[0026] The polarizing plate can be produced by any appropriate method. Specifically, the polarizing plate may include a polarizer produced from a single-layer resin film, or may include a polarizer obtained by using a laminate of two or more layers.

[0027] A typical method for producing a polarizer from the single-layer resin film includes dyeing the resin film with a dichroic substance such as iodine or a dichroic dye and stretching it. Examples of the resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films. This method may further include insolubilization, swelling, crosslinking, and the like. A polarizing plate can be obtained by laminating a protective layer on at least one side of the resulting polarizer. Since this production method is well known and commonly used in the art, a detailed description thereof will be omitted.

[0028] Specific examples of polarizers 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 laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. A 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 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, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in the orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the orientation of polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through treatment steps in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through drying shrinkage treatment.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 any suitable protective layer may be laminated depending on the purpose on the surface obtained by peeling the resin substrate from the resin substrate / polarizer laminate or on the surface opposite to the peeled surface. Details of the method for producing such a polarizer are described in, for example, JP 2012-73580 A and Japanese Patent No. 6,470,455 A. The entire disclosures of these publications are incorporated herein by reference.

[0029] A-2. Retardation Layer The thickness of the retardation layer depends on its configuration (whether it is a single layer or has a laminated structure), but is preferably 8 μm or less, more preferably 5 μm or less. On the other hand, the thickness of the retardation layer is, for example, 1 μm or more. When the retardation layer has a laminated structure, the "thickness of the retardation layer" means the sum of the thicknesses of the individual retardation layers. Specifically, the "thickness of the retardation layer" does not include the thickness of the adhesive layer.

[0030] As the retardation layer, a layer of orientation-solidified liquid crystal compounds (liquid crystal orientation-solidified layer) is preferably used. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to non-liquid crystal materials, so the thickness of the retardation layer required to obtain a desired in-plane retardation can be significantly reduced. Therefore, a polarizing plate with a retardation layer can be significantly thinned. In this specification, the term "orientation-solidified layer" refers to a layer in which liquid crystal compounds are oriented in a predetermined direction within the layer and the orientation state is fixed. Note that the term "orientation-solidified layer" encompasses a concept including an orientation-solidified layer obtained by curing a liquid crystal monomer, as described below. In the retardation layer, typically, rod-shaped liquid crystal compounds are oriented in a state aligned in the slow axis direction of the retardation layer (homogeneous orientation).

[0031] The liquid crystal alignment solidified layer can be formed by performing an alignment treatment on the surface of a predetermined substrate, 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. Any appropriate alignment treatment can be used as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. 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 vapor deposition and photoalignment treatment. Any appropriate treatment conditions can be used for the various alignment treatments depending on the purpose.

[0032] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction of the substrate surface.

[0033] 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.

[0034] Specific examples of liquid crystal compounds and details of the method for forming the alignment solidified layer are described in JP-A-2006-163343, the disclosure of which is incorporated herein by reference.

[0035] As described above, the retardation layer 20 may be a single layer or may have a laminated structure of two or more layers.

[0036] As shown in FIG. 1 , in one embodiment where the retardation layer 20 is a single layer, the retardation layer 20 can function as a λ / 4 plate. Specifically, the Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and even more preferably 110 nm to 160 nm. The thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation of the λ / 4 plate. When the retardation layer is the above-mentioned liquid crystal alignment solidified layer, its thickness is, for example, 1.0 μm to 2.5 μm. In this embodiment, 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 44° to 46°. In this embodiment, the retardation layer preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases depending on the wavelength of the measurement light. In this embodiment, the laminate may further include a layer (another retardation layer, not shown) that exhibits a refractive index characteristic of nz > nx = ny and is disposed between the retardation layer 20 and the second protective film 32.

[0037] In another embodiment in which the retardation layer 20 is a single layer, the retardation layer 20 can function as a λ / 2 plate. Specifically, the Re(550) of the retardation layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 230 nm to 280 nm. The thickness of the retardation layer can be adjusted so as to obtain the desired in-plane retardation of the λ / 2 plate. When the retardation layer is the above-mentioned liquid crystal alignment solidified layer, its thickness is, for example, 2.0 μm to 4.0 μm. In this embodiment, the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 12° to 16°.

[0038] As shown in FIG. 2, when the retardation layer 20 has a laminated structure, the retardation layer 20 has a two-layer laminated structure, for example, in which a first retardation layer (H layer) 21 and a second retardation layer (Q layer) 22 are arranged in this order from the polarizing plate side. The H layer can typically function as a λ / 2 plate, and the Q layer can typically function as a λ / 4 plate. Specifically, the Re(550) of the H layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, and even more preferably 230 nm to 280 nm; the Re(550) of the Q layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and even more preferably 110 nm to 150 nm. The thickness of the H layer can be adjusted to obtain the desired in-plane retardation of the λ / 2 plate. When the H layer is the above-mentioned liquid crystal alignment solidified layer, its thickness is, for example, 2.0 μm to 4.0 μm. The thickness of the Q layer can be adjusted to obtain the desired in-plane retardation of the λ / 4 plate. When the Q layer is the above-mentioned liquid crystal alignment solidified layer, its thickness is, for example, 1.0 μm to 2.5 μm. In this embodiment, the angle between the slow axis of the H layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 12° to 16°; the angle between the slow axis of the Q layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 72° to 76°. When the retardation layer 20 has a laminated structure, each layer (e.g., the H layer and the Q layer) may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases depending on the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases depending on the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation value changes little depending on the wavelength of the measurement light.

[0039] The retardation layer 20 (or each layer when it has a laminated structure) typically exhibits the relationship of nx>ny=nz in refractive index characteristics. Note that "ny=nz" does not only include the case where ny and nz are completely equal, but also includes 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. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.

[0040] As described above, the retardation layer is preferably a liquid crystal alignment solidified layer. Examples of the liquid crystal compound include a liquid crystal compound whose liquid crystal phase is a nematic phase (nematic liquid crystal). Examples of such liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The mechanism by which the liquid crystal compound exhibits liquid crystallinity may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

[0041] When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the orientation 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, the alignment state can be fixed by polymerizing or crosslinking the liquid crystal monomers with each other. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystals. Therefore, the formed retardation layer does not undergo, for example, a transition to a liquid crystal phase, a glass phase, or a crystalline phase due to temperature changes, which is specific to liquid crystal compounds. As a result, the retardation layer becomes a retardation layer that is not affected by temperature changes and has excellent stability.

[0042] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type of the liquid crystal monomer. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

[0043] Any appropriate liquid crystal monomer can be used as the liquid crystal monomer. For example, polymerizable mesogen compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0,261,712, DE 19,504,224, DE 4,408,171, and GB 2,280,445 can be used. Specific examples of such polymerizable mesogen compounds include LC242 (product name) from BASF, E7 (product name) from Merck, and LC-Silicon-CC3767 (product name) from Wacker-Chem. Nematic liquid crystal monomers are preferred as the liquid crystal monomer.

[0044] A-3. Relationship between Thickness of Polarizing Plate and Retardation Layer The sum of the thickness of the polarizing plate and the thickness of the retardation layer (sometimes simply referred to as "total thickness") is 50 μm or less, preferably 45 μm or less, and more preferably 40 μm or less. On the other hand, the total thickness is, for example, 25 μm or more.

[0045] The ratio of the thickness of the polarizing plate to the thickness of the retardation layer (thickness of polarizing plate / thickness of retardation layer, sometimes simply referred to as "thickness ratio") is 5 or more, preferably 8 or more, and more preferably 10 or more. On the other hand, the thickness ratio is preferably 30 or less, and more preferably 25 or less.

[0046] The laminate used in the manufacturing method according to an embodiment of the present invention has a small total thickness and a large ratio of the polarizing plate thickness to the total thickness (a small ratio of the retardation layer thickness). The inventors have found that the above-mentioned warping problem is likely to occur when the total thickness and thickness ratio are within the above-mentioned predetermined range. More specifically, when the difference between the polarizing plate thickness and the retardation layer thickness is not large, and when the polarizing plate thickness is excessively large, the warping problem is unlikely to occur in the retardation layer-attached polarizing plate. Based on this new knowledge, the inventors have conducted extensive research into suppressing warping and have found that warping can be efficiently suppressed by the manufacturing method according to an embodiment of the present invention.

[0047] A-4. First Protective Film The first protective film 31 can be formed of any appropriate material. Specific examples of forming materials include polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate-based polymers; (meth)acrylic polymers such as polymethyl methacrylate; and cycloolefin-based polymers such as polynorbornene. These may be used alone or in combination of two or more.

[0048] The first protective film has a moisture permeability of 30 g / m at 40°C and 92% RH. ２ Preferably 24 hours or less, more preferably 20 g / m ２ The moisture permeability of the first protective film at 40°C and 92% RH is, for example, 5 g / m or less. ２ ・24 hours or more.

[0049] The thickness of the first protective film is preferably 15 μm to 50 μm, and more preferably 25 μm to 40 μm.

[0050] As described above, the first protective film 31 can be attached to the polarizing plate 10 via a pressure-sensitive adhesive layer. Any appropriate configuration can be employed for the pressure-sensitive adhesive layer. Specific examples include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, epoxy pressure-sensitive adhesives, and polyether pressure-sensitive adhesives. Pressure-sensitive adhesives with desired properties can be prepared by adjusting the type, number, combination, and compounding ratio of monomers forming the base resin of the pressure-sensitive adhesive, as well as the amount of cross-linking agent, reaction temperature, reaction time, and the like. The base resin of the pressure-sensitive adhesive may be used alone or in combination of two or more types. The base resin is preferably an acrylic resin (specifically, the pressure-sensitive adhesive layer is preferably composed of an acrylic pressure-sensitive adhesive). The thickness of the pressure-sensitive adhesive layer is, for example, 5 μm to 15 μm. The storage modulus of the pressure-sensitive adhesive layer at 25°C is, for example, 1.0 × 10 ５ Pa ~ 1.0 x 10 ７ It is Pa.

[0051] In one embodiment, a laminate (hereinafter referred to as a "surface protection film") is used in which the pressure-sensitive adhesive layer is formed on a first protective film in advance. The thickness of the surface protection film is preferably 30 μm to 60 μm, and more preferably 30 μm to 50 μm. As described above, when the first protective film is peeled off, it can be peeled off together with the pressure-sensitive adhesive layer (together with the surface protection film).

[0052] A-5. Second Protective Film The second protective film 32 may be made of any appropriate plastic film. Specific examples of plastic films include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film. As described above, the second protective film 32 may function as a separator. Specifically, a plastic film whose surface is coated with a release agent is preferably used as the second protective film 32. Specific examples of the release agent include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.

[0053] The second protective film has a moisture permeability of 30 g / m at 40°C and 92% RH.２ Preferably 24 hours or less, more preferably 20 g / m ２ The moisture permeability of the second protective film at 40°C and 92% RH is, for example, 5 g / m or less. ２ ・24 hours or more.

[0054] The thickness of the second protective film is preferably 20 μm to 80 μm, and more preferably 35 μm to 55 μm.

[0055] A-6. Preparation of Laminate The laminate 100 can be obtained, for example, by laminating the polarizing plate 10 and the retardation layer 20 to prepare a laminate precursor, and then laminating the first protective film 31 and the second protective film 32 on the obtained laminate precursor.

[0056] The polarizing plate 10 and the retardation layer 20 are laminated, for example, while they are transported by rolls (so-called roll-to-roll method). The lamination is typically performed by transferring a liquid crystal alignment solidified layer formed on a substrate. As shown in Figure 2, when the retardation layer has a laminated structure, each retardation layer may be laminated (transferred) sequentially onto the polarizing plate, or a laminate of retardation layers may be laminated (transferred) onto the polarizing plate.

[0057] The transfer is performed using, for example, an active energy ray-curable adhesive. The thickness of the active energy ray-curable adhesive after curing (thickness of the adhesive layer) is preferably 0.4 μm or more, more preferably 0.4 μm to 3.0 μm, and even more preferably 0.6 μm to 1.5 μm. The warping of a retardation layer-attached polarizing plate having the above-mentioned predetermined total thickness and thickness ratio is mainly caused by the adhesive used to laminate the polarizing plate and the retardation layer (specifically, shrinkage during curing of the active energy ray-curable adhesive), and warping may occur in the laminate precursor obtained by laminating the polarizing plate 10 and the retardation layer 20.

[0058] Fig. 3 is a cross-sectional view showing an example of a warped state of a laminate precursor. In Fig. 3, hatching is omitted from the cross section of the laminate precursor to make the drawing easier to see. In the example shown in Fig. 3, a convex warp occurs in the laminate precursor 90 toward the polarizing plate 10. The warp tends to occur along the absorption axis direction of the polarizing plate 10 (polarizer 11).

[0059] The laminate of the polarizing plate 10 and the retardation layer 20 has a water vapor content (A1) of 10.2 g / m ３ It is preferable that the lamination is carried out under the following conditions: The amount of water vapor (A1) during lamination is more preferably 6.0 g / m ３ ~10.0g / m ３ and more preferably 8.0 g / m ３ ~9.5g / m ３ By performing lamination in an environment where the amount of water vapor (A1) is in this range, for example, the effect of the humidification treatment described below becomes significant. Such an amount of water vapor (A1) in lamination can be achieved, for example, by changing the relative humidity depending on the temperature within a temperature range of 18°C ​​to 25°C. For example, when the temperature is 18°C, the amount of water vapor (A1) can be achieved by setting the relative humidity to 65% RH or less; or, for example, when the temperature is 20°C, the amount of water vapor (A1) can be achieved by setting the relative humidity to 55% RH or less; or, for example, when the temperature is 23°C, the amount of water vapor can be achieved by setting the relative humidity to 45% RH or less. The lower limit of the relative humidity can be, for example, 30% RH.

[0060] In one embodiment, the moisture permeability of either the protective layer 12 or the retardation layer 20 at 40°C and 92% RH is preferably 300 g / m ２ 24 hours or more, more preferably 400 g / m ２ ・24h~1000g / m ２ 24h, more preferably 400g / m ２ ・24h~800g / m ２ When either the protective layer 12 or the retardation layer 20 has such moisture permeability, the effect of the humidification treatment described below can be significantly obtained.

[0061] As described above, when the laminate further includes other functional layers (for example, a conductive layer, other retardation layers), the functional layers can be laminated or formed at predetermined positions by any appropriate method.

[0062] The laminate precursor having at least the polarizing plate 10 and the retardation layer 20 is laminated onto the first protective film 31, for example, by bonding the surface protective film. The laminate precursor is laminated onto the second protective film 32, for example, by using a pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive (the thickness of the pressure-sensitive adhesive layer disposed between the retardation layer 20 and the second protective film 32) is, for example, 10 μm to 20 μm.

[0063] B. Moisture Treatment The laminate is subjected to a humidification treatment. By subjecting the laminate to a humidification treatment, moisture is added to the laminate (preferably, the polarizer), and a retardation layer-attached polarizing plate with reduced warpage can be obtained. For example, the laminate is subjected to a humidification treatment under conditions where the amount of water vapor is 10.5 g / m ３ The humidification treatment is carried out by placing the film under the above environment. The amount of water vapor (A2) during the humidification treatment is preferably 10.5 g / m ３ ~30g / m ３ and more preferably 11 g / m ３ ~20g / m ３ is.

[0064] The amount of water vapor (A2) during the humidification treatment can be achieved, for example, by setting the relative humidity to 80% RH or higher when the temperature is 18° C., or by setting the relative humidity to 60% RH or higher when the temperature is 20° C., or by setting the relative humidity to 50% RH or higher when the temperature is 23° C. The upper limit of the relative humidity can be, for example, 100% RH.

[0065] In one embodiment, the laminate is subjected to a humidification treatment in an environment where the amount of water vapor is greater than the amount of water vapor (A1). More specifically, the difference between the amount of water vapor (A2) during the humidification treatment and the amount of water vapor (A1) is 0.5 g / m or less. ３ It is preferable that the content is 1.0 g / m or more, and more preferably 1.0 g / m ３ ~28g / m ３ and more preferably 1.0 g / m３ ~12g / m ３ and particularly preferably 1.5 g / m ３ ~10g / m ３ and most preferably 1.5 g / m ３ ~8g / m ３ By humidifying under such conditions, an appropriate amount of moisture can be imparted to the laminate. More specifically, moisture can be imparted to the laminate without causing the laminate to shrink. If too much moisture is imparted to the laminate in the humidifying treatment, for example, warpage may occur in a direction opposite to the initial warpage and / or warpage may occur in a direction perpendicular to the initial warpage within the plane.

[0066] In one embodiment, the laminate is preferably subjected to a humidification treatment so that the weight per unit area of ​​the laminate portion from the polarizing plate to the adhesive layer increases by 0.1% or more. The weight increase per unit area of ​​the laminate portion from the polarizing plate to the adhesive layer due to the humidification treatment is more preferably 0.1% to 2.0%, even more preferably 0.1% to 1.0%, and particularly preferably 0.1% to 0.5%. By controlling the weight increase within this range, the polarizer can absorb the desired amount of moisture. As a result, warping of the resulting retardation layer-attached polarizing plate can be effectively suppressed. Here, the laminate portion from the polarizing plate to the adhesive layer refers to, for example, a laminate portion 80 of the polarizing plate 10, adhesive layer 40, retardation layer 20 (including the adhesive layer if the retardation layer has a laminated structure), and adhesive layer 50, as shown in FIG. 4 . Note that hatching is omitted from the cross section of the laminate portion in FIG. 4 .

[0067] The humidification treatment time is preferably 6 hours or more, more preferably 12 hours or more, and even more preferably 24 hours or more. With such a treatment time, for example, the desired weight gain (water absorption) can be satisfactorily achieved. On the other hand, the humidification treatment time is, for example, 150 hours or less. Since the effect remains unchanged even if the humidification treatment time is excessively long, the upper limit of the humidification treatment time can be determined by balancing the desired weight gain and production efficiency.

[0068] During the humidification treatment, the laminate is placed with its main surface at an angle relative to the placement surface. Fig. 5 is a cross-sectional view showing an example of the state in which the laminate is placed on the placement surface. Note that in Fig. 5, hatching has been omitted from the cross section of the laminate to make the drawing easier to see. In the illustrated example, the laminate 100 is placed on the placement surface S such that the main surface 100a of the laminate 100 forms an angle θ with the placement surface S. The angle θ is greater than 0° and equal to or less than 90°, preferably 70° to 90°, and more preferably 80° to 90°.

[0069] In the illustrated example, n sheet-like laminates 100 are arranged so that the main surfaces of adjacent laminates 100 overlap. Typically, prior to the humidification treatment, the laminate is cut into sheets of a predetermined size. The sheet-like laminates are preferably obtained by cutting a long laminate precursor. Specifically, it is preferable to obtain sheet-like laminate precursors by cutting a long laminate precursor, and then laminate the sheet-like laminate precursors with a first protective film and a second protective film to obtain sheet-like laminates. This configuration, for example, eliminates the need for large-scale roll-to-roll transport equipment, thereby improving manufacturing efficiency. Cutting is preferably performed so that the resulting sheet-like laminates are superimposed on the warped laminate precursor, as shown in FIG. 5 . In one embodiment, the long laminate precursor is cut at an angle of 45° to the longitudinal direction. In another embodiment, the long laminate precursor is cut along the longitudinal and width directions (directions perpendicular to the longitudinal direction).

[0070] According to this embodiment, moisture can be efficiently absorbed into the laminate (polarizer), and retardation layer-attached polarizing plates with reduced warpage can be produced with high yield. Specifically, by adopting a state in which the main surface of the laminate is angled with respect to the mounting surface, as shown in FIG. 5, it is possible to perform a humidification treatment on multiple laminates at once in a uniform state (e.g., a state in which the force applied to the laminate is uniform), as shown in FIG. 5. As a result, moisture can be uniformly added to multiple laminates (e.g., a single humidification treatment can satisfactorily achieve an increase in weight of the laminated portion between the polarizer and the retardation layer in multiple laminates), and retardation layer-attached polarizing plates with reduced warpage can be produced with high yield. In addition, the resulting retardation layer-attached polarizing plates can also have excellent appearance.

[0071] The present invention will be described in detail below using examples, but the present invention is not limited to these examples. The thickness and moisture permeability are values ​​measured by the following measurement methods. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. <Thickness> Thicknesses of 10 μm or less were measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). Thicknesses of more than 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Moisture permeability> Moisture permeability was determined using the cup method (JIS Z 0208).

[0072] Example 1 (Preparation of Polarizing Plate) A long, amorphous, isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) with a Tg of approximately 75°C was used as the thermoplastic resin substrate. One side of this resin substrate was subjected to a corona treatment. A PVA-based resin (100 parts by weight) containing 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 "GOHSEFIRM") 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 uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (in-air auxiliary stretching treatment). Next, the laminate was immersed for 30 seconds 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) having a liquid temperature of 40°C (insolubilization treatment), then immersed for 60 seconds in a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide with 100 parts by weight of water in a weight ratio of 1:7) having a liquid temperature of 30°C while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment), then immersed for 30 seconds 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) having a liquid temperature of 40°C (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls operating at different peripheral speeds to a total stretch ratio of 5.5 (underwater stretching treatment). The laminate was then immersed in a cleaning bath (an 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). The laminate was then dried in an oven maintained at approximately 90°C and brought into contact with a SUS heated roll maintained at a surface temperature of approximately 75°C (drying shrinkage treatment). In this way, a polarizer having a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate / polarizer configuration was obtained.

[0073] An HC-COP film (thickness: 27 μm) was attached as a protective layer to the polarizer side of the obtained laminate via a UV-curable adhesive. The HC-COP film was a film in which an HC layer (thickness: 2 μm) was formed on a cycloolefin resin (COP) film (thickness: 25 μm), and the COP film was attached to the polarizer side. Next, the resin substrate was peeled off from the polarizer to obtain a polarizing plate having a HC-COP film (protective layer) / polarizer configuration.

[0074] (Preparation of Retardation Layer) 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Irgacure 907") were dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

[0075] The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth to perform an alignment treatment. The direction of the alignment treatment was set to be 15° from the viewing side with respect to the direction of the absorption axis of the polarizer when it was attached to the polarizing plate. The liquid crystal coating solution was applied to this alignment-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with 1 mJ / cm using a metal halide lamp. ２ The liquid crystal layer was cured by irradiating the PET film with light of 1000 nm to form a liquid crystal alignment solidified layer A (H layer). The liquid crystal alignment solidified layer A had a thickness of 2.5 μm and an in-plane retardation Re(550) of 270 nm. Furthermore, the liquid crystal alignment solidified layer A exhibited a refractive index characteristic of nx>ny=nz.

[0076] A liquid crystal alignment layer B (Q layer) was formed on a PET film in the same manner as above, except that the coating thickness was changed and the alignment treatment direction was set to a 75° angle with respect to the absorption axis direction of the polarizer when viewed from the viewing side. The liquid crystal alignment layer B had a thickness of 1.5 μm and an in-plane retardation Re(550) of 140 nm. Furthermore, the liquid crystal alignment layer B exhibited refractive index characteristics of nx > ny = nz.

[0077] (Preparation of Laminate) The obtained liquid crystal alignment solidified layer A (H layer) and liquid crystal alignment solidified layer B (Q layer) were transferred in this order to the polarizer side of the obtained polarizing plate. 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 alignment solidified layer A was 15°, and the angle between the absorption axis of the polarizer and the slow axis of the alignment solidified layer B was 75°. Each transfer was performed via an ultraviolet-curable adhesive (thickness 1.0 μm). In this way, a laminate precursor was obtained. The transfer (lamination) was performed while transporting with a roll. Furthermore, the transfer (lamination) was performed in an atmosphere with a water vapor content of 9.3 g / m ３ The test was carried out under an environment of 23° C. and 45% RH. The total thickness of the obtained laminate precursor was 36 μm, and the thickness ratio was 8.

[0078] The obtained long laminate precursor was cut in a direction at an angle of 45° to the longitudinal direction and the width direction (the direction perpendicular to the longitudinal direction) to obtain a 165 mm x 80 mm sheet of the laminate precursor. The longitudinal direction corresponds to the absorption axis direction of the polarizer.

[0079] Next, a surface protection film (thickness: 48 μm) was attached to the protective layer side of the polarizing plate of the laminate precursor. The surface protection film was a PET film (thickness: 38 μm, moisture permeability: 18 g / m ２ A pressure-sensitive adhesive layer (thickness: 10 μm) was formed on the laminate precursor (24 h). Furthermore, a separator (thickness: 38 μm, moisture permeability: 18 g / m) was attached to the liquid crystal alignment solidified layer B (Q layer) side of the laminate precursor. ２ The laminates were laminated together with a pressure-sensitive adhesive layer (thickness: 15 μm) to obtain a 165 mm × 80 mm sheet-like laminate. Similarly, a total of 500 165 mm × 80 mm sheet-like laminates were produced.

[0080] (Humidification Treatment) Five hundred of the obtained sheet-like laminates were stacked to form a laminate assembly, and the laminate was subjected to a humidification treatment while being placed so that the main surface of each laminate formed an angle of 90° with respect to the mounting surface, as shown in FIG. 5 . Specifically, 500 laminates (laminate assembly) were housed in a case of a predetermined size, and the humidification treatment was performed while the main surface of each laminate formed an angle of 90° with respect to the inner bottom surface (mounting surface) of the case. Here, the long sides of each laminate were in contact with the inner bottom surface of the case, and the humidification treatment was performed while unfoamed polystyrene (PS) sheets were filled in the empty space within the case (the space between the main surfaces of the laminates located at the front and rear ends of the laminate assembly and the inner side surface of the case). The humidification treatment was performed at 23°C and 60% RH (water vapor content of 12.4 g / m). ３ ) for 24 hours. In this way, a polarizing plate with a retardation layer was obtained.

[0081] Example 2 A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that a TAC film (thickness: 27 μm) was used as the protective layer instead of the HC-COP film.

[0082] [Comparative Example 1] A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the long laminate precursor was not cut and that the long laminate was prepared and wound into a roll and subjected to the humidification treatment.

[0083] [Comparative Example 2] A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that in the humidification treatment, the laminate assembly was placed so that the main surface of each laminate formed an angle of 0° with respect to the placement surface (500 laminates were placed in a stack on the placement surface).

[0084] [Comparative Example 3] Humidification treatment was performed at 23°C and 45% RH (water vapor amount 9.3 g / m ３ A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the heating was carried out at 100° C. for 24 hours.

[0085] [Reference Example 1] A long roll of a 60 μm-thick PVA-based resin film was uniaxially stretched in the longitudinal direction using a roll stretching machine to a total stretch ratio of 6.0 times, while simultaneously undergoing swelling, dyeing, crosslinking, and washing treatments, and finally drying treatment to produce a 22 μm-thick polarizer. A TAC film (71 μm thick) with an HC layer was laminated to one side of the obtained polarizer. Furthermore, a polycarbonate resin retardation film (58 μm thick) exhibiting reverse dispersion wavelength dependence and having an Re(550) of 140 nm was laminated to the other side of the polarizer. The retardation film was laminated so that the angle between the slow axis and the absorption axis of the polarizer was 45°. In this way, a retardation layer-attached polarizing plate was obtained. The total thickness of the retardation layer-attached polarizing plate was 151 μm, and the thickness ratio was 1.6. This retardation layer-attached polarizing plate was cut into a size of 165 mm x 80 mm and placed on a flat surface, and no warping was observed.

[0086] [Reference Example 2] A polarizer having a thickness of 22 μm was produced in the same manner as in Reference Example 1. A TAC film (thickness 91 μm) with an HC layer was bonded to one surface of the obtained polarizer, and a TAC film (thickness 80 μm) was bonded to the other surface to obtain a polarizing plate. A retardation layer-attached polarizing plate having a configuration of HC layer-attached TAC film / polarizer / TAC film / adhesive layer / retardation layer (H layer) / adhesive layer / retardation layer (Q layer) was obtained in the same manner as in Example 1, except that this polarizing plate was used. The total thickness of the retardation layer-attached polarizing plate was 197 μm, and the thickness ratio was 48. This retardation layer-attached polarizing plate was cut into a size of 165 mm × 80 mm and placed on a flat surface, and no warping was observed.

[0087] The following evaluations were performed on the Examples and Comparative Examples. The evaluation results are summarized in Tables 1 and 2. <Evaluation> 1. Weight change per unit area: Using an electronic balance, the weight of the laminated portion from the polarizing plate to the pressure-sensitive adhesive layer (laminate portion 80 shown in FIG. 4) was measured before and after humidification, and the weight change was calculated from the obtained measurements. 2. Amount of warpage: A sheet of the laminate precursor and the retardation layer-attached polarizing plate were placed on a flat surface with the retardation layer side facing the flat surface, and the height of the highest part from the flat surface was measured to determine the amount of warpage. Note that a convex warpage toward the surface on which the plate was placed is represented by "positive (+)" and a convex warpage toward the opposite side of the surface on which the plate was placed is represented by "negative (-)." In the table, "(MD)" corresponds to the transport direction of the roll transport and the absorption axis direction of the polarizer. 3. Appearance: The appearance of the obtained retardation layer-attached polarizing plate was visually observed. Note that the evaluation criteria are as follows: (Evaluation criteria) Good: No dents were observed. Poor: Dents were observed.

[0088]

[0089]

[0090] As is clear from Table 1, in Examples 1 and 2, weight changes due to humidification treatment were confirmed within a range of 0.1% to 0.4%, and the warpage of the resulting retardation layer-attached polarizing plates was within a range of -20 mm to +20 mm (- indicates warpage in the MD direction, and + indicates warpage in the TD direction perpendicular to the MD direction). Thus, in Examples 1 and 2, moisture could be uniformly applied to multiple laminates, and the degree of correction of warpage occurring in the laminate precursors was highly uniform. In contrast, in Comparative Example 2, in which the laminates were placed one on top of the other on the mounting surface, variation in weight change due to humidification treatment was confirmed. Specifically, the laminates located at the top of the laminate assembly were subjected to a smaller force than the laminates located at the bottom, and the laminates located at the top absorbed more moisture than the laminates located at the bottom. The laminates located at the top exhibited warpage in the opposite direction to the warpage occurring in the laminate precursor. Meanwhile, the warpage occurring in the laminate precursors in the laminates located at the bottom was improved. Thus, variations in the degree of correction of the warp that occurred in the laminate precursor were confirmed, and dents were also confirmed in the obtained retardation layer-attached polarizing plate.

[0091] In Comparative Example 1, in which the film was humidified in a rolled state, the weight per unit area of ​​the inner part of the roll did not change, and warpage was not improved. As is clear from the Reference Example, such warpage is a problem specific to polarizing plates with a retardation layer, which have a small total thickness and in which the ratio of the polarizing plate thickness to the total thickness is large.

[0092] The retardation layer-attached polarizing plate according to one embodiment of the present invention is used as a retardation layer-attached polarizing plate for an image display device, and can be particularly suitably used for a curved, bendable, foldable, or rollable image display device. Representative examples of the image display device include a liquid crystal display device, an organic EL display device, and an inorganic EL display device.

[0093] REFERENCE SIGNS LIST 10 Polarizing plate 11 Polarizer 12 Protective layer 20 Retardation layer 21 First retardation layer (H layer) 22 Second retardation layer (Q layer) 31 First protective film 32 Second protective film 90 Laminate precursor 100 Laminate

Claims

1. A laminate is prepared, which includes a first protective film, a polarizing plate including a polarizer and a protective layer disposed on at least one side of the polarizer, a retardation layer, and a second protective film in this order, in which the sum of the thickness of the polarizing plate and the thickness of the retardation layer is 50 μm or less, and the ratio of the thickness of the polarizing plate to the thickness of the retardation layer is 5 or more; and ３ placing the laminate in the above environment for humidification treatment; and placing the laminate in a state in which a main surface of the laminate is angled with respect to the placement surface.

2. The method according to claim 1, further comprising laminating the polarizing plate and the retardation layer to obtain a laminate precursor.

3. The method according to claim 2, further comprising cutting the laminate precursor into sheets.

4. The method according to any one of claims 1 to 3, wherein the humidification treatment is carried out in a state where a plurality of the laminates are arranged in an array.

5. The first protective film has a moisture permeability of 30 g / m at 40° C. and 92% RH. ２ The method according to any one of claims 1 to 4, wherein the period is 24 hours or less.

6. The second protective film has a moisture permeability of 30 g / m at 40° C. and 92% RH. ２ The method according to any one of claims 1 to 5, wherein the period is 24 hours or less.

7. The method according to claim 1, further comprising laminating the polarizing plate and the retardation layer while transporting them with a roll.

8. The method according to claim 1, further comprising laminating the polarizing plate and the retardation layer with an active energy ray-curable adhesive.

9. The method according to claim 8, wherein the active energy ray-curable adhesive has a thickness of 0.4 μm or more after curing.

10. A manufacturing method according to any one of claims 1 to 9, wherein the laminate has an adhesive layer arranged on the side of the retardation layer on which the polarizing plate is not arranged, and the weight increase per unit area of ​​the laminated portion of the polarizing plate, the retardation layer and the adhesive layer due to the humidification treatment is 0.1% or more.

11. The method according to any one of claims 1 to 10, wherein the humidification treatment is carried out for 6 hours or more.

12. The amount of water vapor during the humidification process is 10.5 g / m ３ ~30g / m ３ The method according to any one of claims 1 to 11, 13. The polarizing plate and the retardation layer are placed in a vacuum chamber with a water vapor content of 10.2 g / m ３ 13. A method according to any one of claims 1 to 12, comprising laminating under the following conditions:

14. The amount of water vapor during the humidification treatment is 0.5 g / m less than the amount of water vapor during lamination of the polarizing plate and the retardation layer. ３ The method according to any one of claims 1 to 13, wherein the concentration of the at least one ion is more than or equal to 100%.

15. The moisture permeability of the retardation layer or the protective layer at 40° C. and 92% RH is 300 g / m ２ The method according to any one of claims 1 to 14, wherein the period is 24 hours or more.

16. The manufacturing method according to any one of claims 1 to 15, wherein the polarizing plate has a protective layer disposed only on the side of the polarizer on which the retardation layer is not disposed.

17. A method for producing a film according to any one of claims 1 to 16, wherein the center of gravity of the polarizer in the thickness direction is located on the retardation layer side of the center of gravity of the laminated portion of the polarizing plate and the retardation layer in the thickness direction.

18. The method according to any one of claims 1 to 17, wherein the retardation layer is a layer in which a liquid crystal compound is aligned and solidified.

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