JP2022156655A - Method for manufacturing polarizing plate with retardation layer and method for storing polarizing plate with retardation layer - Google Patents

Abstract

To provide a polarizing plate with a retardation layer with which warpage is suppressed.SOLUTION: A method for manufacturing a polarizing plate with a retardation layer according to an embodiment of the present invention includes: preparing a laminate that has a polarizing plate that includes a polarizer having first and second principal surfaces facing each other and a first protective layer arranged on the first principal surface of the polarizer and a retardation layer arranged on the second principal surface of the polarizer; packing the laminate with a packaging material the thermal conductivity of which is 0.2 W/m-k or less and obtaining a package; and storing the package. The difference in moisture vapor permeability at 40°C and 92% RH between a lamination part from a layer arranged adjacent to the second principal surface of the polarizer to the retardation layer and the first protective layer is 350 g/m2-24h or greater.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a method for producing a polarizing plate with a retardation layer and a method for storing the polarizing plate with a retardation layer.

Image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) are rapidly spreading. Polarizing plates and retardation plates are typically 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, the possibility of curving, bending, folding, and winding an image display device using a flexible substrate (for example, a resin substrate) has been investigated. As a polarizing plate with a retardation layer used in such an image display device, a thin polarizing plate with a retardation layer is desired. However, the thin polarizing plate with a retardation layer has a problem that warping is likely to occur. This warping can cause, for example, manufacturing defects in the image display device.

Japanese Patent No. 3325560

The present invention has been made to solve the conventional problems described above, and a main object thereof is to provide a retardation layer-attached polarizing plate in which warping is suppressed.

An embodiment of the present invention provides a method for manufacturing a polarizing plate with a retardation layer. The manufacturing method comprises a polarizing plate including a polarizer having a first principal surface and a second principal surface facing each other and a first protective layer disposed on the first principal surface side of the polarizer; and the polarizer. Prepare a laminate having a retardation layer arranged on the second main surface side of the above, and pack the laminate with a packing material having a thermal conductivity of 0.2 W / m K or less to form a package. and storing the package, comprising: a laminated portion from a layer disposed adjacent to the second main surface of the polarizer to the retardation layer; and the first protective layer; The difference in moisture permeability at 40° C. and 92% RH is 350 g/m ² ·24 h or more.
In one embodiment, the moisture permeability of the first protective layer at 40° C. and 92% RH is 100 g/m ² ·24 h or less.
In one embodiment, the laminated portion has a moisture permeability of 400 g/m ² ·24 h or more at 40° C. and 92% RH.
In one embodiment, the polarizing plate has a second protective layer arranged between the polarizer and the retardation layer.
In one embodiment, the retardation layer is a fixed alignment layer of a liquid crystal compound.
In one embodiment, the retardation layer has a laminated structure of two or more layers.
In one embodiment, the laminate has the first protective film, the polarizing plate, the retardation layer, and the second protective film in this order.
In one embodiment, the moisture permeability of the first protective film at 40° C. and 92% RH is 30 g/m ² ·24 h or less.
In one embodiment, the moisture permeability of the second protective film at 40° C. and 92% RH is 30 g/m ² ·24 h or less.
In one embodiment, the sheet-shaped laminate is packed to obtain the package.
In one embodiment, the sum of the thickness of the polarizing plate and the thickness of the retardation layer is 83 μm or less.
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 manufacturing method includes subjecting the laminate to a humidifying treatment before the packing.
According to another embodiment of the present invention, a method for storing a retardation layer-attached polarizing plate is provided. The storage method includes a polarizing plate including a polarizer having a first principal surface and a second principal surface facing each other and a first protective layer disposed on the first principal surface side of the polarizer; and the polarizer. Prepare a laminate having a retardation layer arranged on the second main surface side of the above, and pack the laminate with a packing material having a thermal conductivity of 0.2 W / m K or less to form a package. and storing the package, comprising: a laminated portion from a layer disposed adjacent to the second main surface of the polarizer to the retardation layer; and the first protective layer; The difference in moisture permeability at 40° C. and 92% RH is 350 g/m ² ·24 h or more.

According to the embodiment of the present invention, by packing a laminate having a polarizing plate and a retardation layer with a predetermined packing material, it is possible to obtain a polarizing plate with a retardation layer in which warping is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing which shows the structure of the outline of the laminated body which concerns on 1st embodiment of this invention. FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a laminate according to a second embodiment of the present invention; FIG. 4 is a schematic perspective view showing an example of a state in which a laminated body is packed; 4 is a cross-sectional view of the package shown in FIG. 3; FIG.

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols used herein 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., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is an in-plane retardation measured at 23° C. with light having a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 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) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of λ nm. For example, “Rth(550)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of 550 nm. Rth(λ) is determined 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 a reference direction. Thus, for example, "45°" means ±45°.

A method for producing a polarizing plate with a retardation layer according to one embodiment of the present invention comprises preparing a laminate having a polarizing plate and a retardation layer, which includes a polarizer and a protective layer, and packing the laminate. including doing

A. 1. Laminate FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a laminate according to a first embodiment of the present invention. The laminate 100 has a first protective film 31, a polarizing plate 10, a retardation layer 20 and a second protective film 32 in this order. The polarizer 11 has a first main surface 11a and a second main surface 11b facing each other, and a first protective layer 12 is arranged on the first main surface 11a side (typically, the viewing side) of the polarizer. . Specifically, the polarizing plate 10 includes a polarizer 11 and a first protective layer 12 arranged on one side of the polarizer 11 (the side on which the retardation layer 20 is not arranged). The retardation layer 20 has a laminated structure including a first retardation layer 21 and a second retardation layer 22 .

FIG. 2 is a schematic cross-sectional view showing the schematic configuration of the laminate according to the second embodiment of the present invention. The laminate 200 has a first protective film 31, a polarizing plate 10, a retardation layer 20 and a second protective film 32 in this order. The polarizer 11 has a first main surface 11a and a second main surface 11b facing each other, and a first protective layer 12 is disposed on the first main surface 11a side (typically, the viewing side) of the polarizer, A second protective layer 13 is arranged on the second main surface 11b side of the polarizer. Specifically, the polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11 (the side on which the retardation layer 20 is not disposed), and the other side of the polarizer 11 ( and a second protective layer 13 disposed between the polarizer 11 and the retardation layer 20). The second embodiment differs from the first embodiment in that a protective layer (second protective layer) is further arranged between the polarizer 11 and the retardation layer 20 .

In the illustrated example, the retardation layer 20 has a laminated structure including the first retardation layer 21 and the second retardation layer 22, but unlike the illustrated example, the retardation layer 20 has a lamination of three or more layers. It may have a structure or may be a single layer.

Although not shown, the laminate may further have other functional layers. The type, properties, number, combination, arrangement, etc. of the functional layers that the laminate may have can be appropriately set according to the purpose. For example, the laminate may further have a conductive layer or an isotropic substrate with a conductive layer. A conductive layer or an isotropic substrate with a conductive layer is typically placed between the retardation layer 20 and the second protective film 32 . In addition, a laminate having a conductive layer or an isotropic substrate with a conductive layer (polarizing plate with a retardation layer) is applied to, for example, 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 have another retardation layer. Other optical properties (for example, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement, etc. of the retardation layer can be appropriately set according to the purpose. As a specific example, on the viewing side of the polarizer 11, another retardation layer that improves visibility when viewed through polarized sunglasses (typically, a layer that imparts (elliptical) circular polarization function, a super A layer that imparts a high retardation) may be provided. By having such a layer, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the obtained polarizing plate with a retardation layer can be suitably applied to an image display device that can be used outdoors.

Each member constituting the laminate can be laminated via any appropriate adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. For example, the first protective film 31 is attached to the polarizing plate 10 via an adhesive layer. The first protective film 31 is applied until the retardation layer-attached polarizing plate obtained by the embodiment of the present invention is used (until it is laminated on the image display panel), or until the final product (image display device). It may be peeled off during the manufacturing process, or it may be mounted as it is on the final product.

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

For example, the retardation layer 20 is attached to the polarizing plate 10 via an adhesive layer (preferably using 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 together via an adhesive layer (preferably using an active energy ray-curable adhesive).

A-1. Polarizing Plate The polarizing plate includes a polarizer and a protective layer. The thickness of the polarizing plate is preferably 20 μm or more, more preferably 25 μm or more, depending on the number of protective layers included. On the other hand, the thickness of the polarizing plate is preferably 75 μm or less. The thickness of the polarizing plate may be 70 μm or less, 65 μm or less, or 60 μm or less. The thickness of the polarizing plate does not include the thickness of the adhesive layer when the polarizer and the protective layer are laminated together.

The polarizer is typically a resin film containing a dichroic substance (eg, iodine). Examples of resin films include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films.

The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 42.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, still more preferably 99.9% or higher.

The protective layer may be formed of any appropriate film that can be used as a protective layer for polarizers. 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, and polysulfone-based resins. , polystyrene, cycloolefin such as polynorbornene, polyolefin, (meth)acrylic, and acetate.

The polarizing plate with a retardation layer obtained by the embodiment of the present invention is typically arranged on the viewer side of the image display device, and the first protective layer 12 is arranged on the viewer side. Therefore, the first 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., if necessary.

The thickness of the protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, still more preferably 15 μm to 35 μm. In addition, when the said surface treatment is performed, the thickness of the 1st protective layer 12 is thickness including the thickness of a surface treatment layer.

In one embodiment, the second protective layer 13 placed between the polarizer 11 and the retardation layer 20 is preferably optically isotropic. As used herein, “optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say. The thickness of the protective layer placed between the polarizer 11 and the retardation layer 20 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, still more preferably 10 μm to 30 μm.

A polarizing plate can be made by any suitable method. Specifically, the polarizing plate may include a polarizer produced from a single-layer resin film, or may include a polarizer obtained using a laminate of two or more layers.

The method of producing a polarizer from the single-layer resin film typically includes dyeing the resin film with a dichroic substance such as iodine or a dichroic dye and stretching the film. As the resin film, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films are used. The method may further include an insolubilization treatment, a swelling treatment, a cross-linking treatment, and the like. A polarizing plate can be obtained by laminating a protective layer on at least one of the obtained polarizers. Since such a manufacturing method is well known and commonly used in the industry, detailed description thereof will be omitted.

Specific examples of the polarizer obtained using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the A polarizer obtained by using a laminate with a PVA-based resin layer formed by coating on a resin base material can be mentioned. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. In addition, in the present embodiment, the laminate is preferably subjected to drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink the laminate by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes subjecting the laminate to an in-air auxiliary 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 improve the crystallinity of PVA and achieve high optical properties even when PVA is coated on a thermoplastic resin. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process, resulting in high optical properties. can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance of the orientation of the polyvinyl alcohol molecules and deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical properties of the polarizer obtained through treatment steps such as dyeing treatment and underwater stretching treatment in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin substrate/polarizer laminate 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 resin substrate/polarizer laminate. Any appropriate protective layer may be laminated according to the purpose on the peeled surface or on the surface opposite to the peeled surface. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. These publications are incorporated herein by reference in their entireties.

A-2. Retardation Layer The thickness of the retardation layer is preferably 8 µm or less, more preferably 5 µm or less, depending on its configuration (whether it is a single layer or has a laminated structure). 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 total thickness of each retardation layer. Specifically, the "thickness of the retardation layer" does not include the thickness of the adhesive layer.

As the retardation layer, an alignment fixed layer of a liquid crystal compound (liquid crystal alignment fixed layer) is preferably used. By using a liquid crystal compound, for example, the difference between nx and ny in the resulting retardation layer can be significantly increased compared to a non-liquid crystal material. thickness can be significantly reduced. Therefore, it is possible to realize a remarkable thinning of the polarizing plate with the retardation layer. As used herein, the term "fixed alignment layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction and the alignment state is fixed. In addition, the "alignment fixed layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer as described later. In the retardation layer, rod-shaped liquid crystal compounds are typically aligned in the slow axis direction of the retardation layer (homogeneous alignment).

The liquid crystal alignment fixed layer is formed by subjecting the surface of a predetermined base material to an alignment treatment, coating the surface with a coating liquid containing a liquid crystal compound, and orienting the liquid crystal compound in a direction corresponding to the alignment treatment. It can be formed by fixing the orientation state. Any appropriate orientation treatment can be adopted as the orientation treatment. Specific examples include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical orientation treatment include magnetic orientation treatment and electric field orientation treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. Arbitrary appropriate conditions can be adopted as the processing conditions for various alignment treatments depending on the purpose.

Alignment of the liquid crystal compound is performed by treatment at a temperature at which a liquid crystal phase is exhibited depending on the type of liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned in accordance with the orientation treatment direction of the surface of the base material.

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 orientation state is fixed by subjecting the liquid crystal compound oriented as described above to a polymerization treatment or a crosslinking treatment.

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

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

Unlike the illustrated example, in one embodiment where the retardation layer is a single layer, the retardation layer can function as a λ/4 plate. Specifically, Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, still more preferably 110 nm to 160 nm. The thickness of the retardation layer can be adjusted so as to obtain the desired in-plane retardation of the λ/4 plate. When the retardation layer is the liquid crystal alignment fixing layer described above, its thickness is, for example, 1.0 μm to 2.5 μm. In the present embodiment, the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, still more preferably 44 ° to 46°. Moreover, the retardation layer preferably exhibits reverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light.

As illustrated, in one embodiment in which the retardation layer 20 has a laminated structure, the retardation layer 20 includes a first retardation layer (H layer) 21 and a second retardation layer in order from the polarizing plate 10 side. It has a two-layer laminated structure in which a layer (Q layer) 22 is arranged. The H layer can typically function as a λ/2 plate and the Q layer can typically function as a λ/4 plate. Specifically, Re(550) of the H layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, still more preferably 230 nm to 280 nm; Re(550) of the Q layer is preferably It is 100 nm to 180 nm, more preferably 110 nm to 170 nm, 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 liquid crystal alignment fixing layer described above, 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 liquid crystal alignment fixing layer described above, its thickness is, for example, 1.0 μm to 2.5 μm. In the present 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°, still more preferably 12°. ~16°; the angle formed by the slow axis of the Q layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, still more preferably 72° ~76°. The arrangement order of the H layer and the Q layer may be reversed, and the angle between the slow axis of the H layer and the absorption axis of the polarizer and the angle between the slow axis of the Q layer and the absorption axis of the polarizer The angles may be reversed. In addition, each layer (for example, the H layer and the Q layer) may exhibit an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and the retardation value increases according to the wavelength of the measurement light. It may exhibit a small positive wavelength dispersion characteristic, or may exhibit a flat wavelength dispersion characteristic in which the retardation value hardly changes even with the wavelength of the measurement light.

The retardation layer (at least one layer if it has a laminated structure) typically exhibits a relationship of nx>ny=nz in refractive index characteristics. Note that "ny=nz" includes not only the case where ny and nz are completely equal but also the case where they are substantially equal. Therefore, ny>nz or ny<nz may be satisfied within a range that does not impair the effects of the present invention. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3.

As described above, the retardation layer is preferably a liquid crystal alignment fixed layer. Examples of the liquid crystal compound include a liquid crystal compound having a nematic liquid crystal phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. Either lyotropic or thermotropic mechanism may be used to develop the liquid crystallinity of the liquid crystal compound. The liquid crystal polymer and liquid crystal monomer may be used alone or in combination.

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 alignment state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (that is, curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, the alignment state can be fixed by polymerizing or cross-linking the liquid crystal monomers. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by cross-linking, but these are non-liquid crystalline. Therefore, the formed retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a change in temperature, which is peculiar to liquid crystalline compounds. As a result, the retardation layer becomes a highly stable retardation layer that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type. 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.

Any appropriate liquid crystal monomer can be employed as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) available from BASF, E7 (trade name) available from Merck, and LC-Sillicon-CC3767 (trade name) available from Wacker-Chem. A nematic liquid crystal monomer is preferable as the liquid crystal monomer.

In another embodiment, the retardation layer 20 includes a first retardation layer 21 that can function as a λ/4 plate and a second retardation layer 22 (so-called It has a laminated structure with a positive C plate). The details of the λ/4 plate are as described above. In the present embodiment, the angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, still more preferably is 44° to 46°. Moreover, the first retardation layer preferably exhibits reverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light.

The thickness direction retardation Rth (550) of the positive C plate 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 is -100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal but also the case where nx and ny are substantially equal. The in-plane retardation Re(550) of the positive C plate is, for example, less than 10 nm.

The second retardation layer having refractive index properties of nz>nx=ny can be made of any suitable material, but preferably consists of a film containing a liquid crystal material fixed in homeotropic alignment. A liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of JP-A-2002-333642. In this case, the thickness of the second retardation layer is preferably 0.5 μm to 5 μm.

A-3. Relationship Between Polarizing Plate and Retardation Layer The sum of the thickness of the polarizing plate and the thickness of the retardation layer (hereinafter sometimes simply referred to as "total thickness") is preferably 83 μm or less, more preferably It is 70 μm or less, more preferably 66 μm or less. On the other hand, the total thickness is, for example, 25 μm or more.

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

The difference in moisture permeability at 40 ° C. and 92% RH between the laminated portion from the layer arranged adjacent to the second main surface 11 b of the polarizer 11 to the retardation layer 20 and the first protective layer 12 is 350 g / m ² ·24 h or more, may be 400 g/m ² ·24 h or more, or may be 500 g/m ² ·24 h or more. The present inventors have found that when the moisture permeability of the layers arranged on the first principal surface side and the second principal surface side of the polarizer has such a relationship, the problem of warpage described above tends to occur. I found Specifically, we found that it is susceptible to the environment (for example, temperature) in which it is placed. Note that "adjacent" means adjoining via an adhesive layer.

The moisture permeability of the first protective layer 12 at 40° C. and 92% RH is, for example, 100 g/m ² ·24 h or less, may be 80 g/m ² ·24 h or less, or 60 g/m ² ·24 h or less. may The first protective layer 12 includes, for example, at least one selected from the group consisting of cycloolefin-based resin films, polyolefin-based resin films, and (meth)acrylic-based resin films. On the other hand, the moisture permeability of the first protective layer 12 at 40° C. and 92% RH is, for example, 5 g/m ² ·24 h or more. In addition, when the said surface treatment is given, the moisture permeability of the 1st protective layer 12 is measured including a surface treatment layer.

The moisture permeability at 40° C. and 92% RH of the laminated portion from the layer arranged adjacent to the second main surface 11b of the polarizer 11 to the retardation layer 20 is, for example, 400 g/m ² ·24 h or more, and 450 g /m ² ·24 h or more, 500 g/m ² ·24 h or more, 600 g/m ² ·24 h or more, or 700 g/m ² ·24 h or more . Such a moisture permeability can be satisfied when an alignment fixed layer of a liquid crystal compound is used as the retardation layer. In the first embodiment shown in FIG. 1, the laminated portion from the layer arranged adjacent to the second main surface 11b of the polarizer 11 to the retardation layer 20 is the first retardation layer 21 to the second It refers to the laminated portion up to the retardation layer 22 . In the second embodiment shown in FIG. 2, the laminated portion from the layer arranged adjacent to the second main surface 11b of the polarizer 11 to the retardation layer 20 is the second protective layer 13 to the second retardation layer Refers to stacks up to 22. As the second protective layer 13, for example, a cellulose resin film is used.

A-4. First Protective Film The first protective film 31 can be made of any suitable 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 methyl methacrylate; cycloolefin polymers such as polynorbornene; These may be used alone or in combination of two or more.

The first protective film preferably has a moisture permeability at 40°C and 92% RH of 30 g/m ² ·24 h or less, more preferably 20 g/m ² ·24 h or less, still more preferably 15 g/m ² · 24 hours or less. On the other hand, the moisture permeability of the first protective film at 40° C. and 92% RH is, for example, 1 g/m ² ·24 h or more.

The thickness of the first protective film is preferably 10 μm to 50 μm, more preferably 15 μm to 35 μm.

As described above, the first protective film 31 can be attached to the polarizing plate 10 via an adhesive layer. Any appropriate configuration can be adopted as the pressure-sensitive adhesive layer. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding amount of the cross-linking agent, the reaction temperature, the reaction time, etc., an adhesive having desired properties according to the purpose. can be prepared. The base resin of the adhesive may be used alone or in combination of two or more. 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 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 to 1.0×10 ⁷ Pa.

In one embodiment, a laminate (hereinafter referred to as "surface protective film") is used in which the pressure-sensitive adhesive layer is formed in advance on the first protective film. The thickness of the surface protective film is preferably 20 μm to 60 μm, more preferably 25 μm to 45 μm. In addition, as described above, when the first protective film is peeled off, it can be peeled off together with the adhesive layer (together with the surface protective film).

A-5. Second Protective Film The second protective film 32 may be composed of any suitable plastic film. Specific examples of plastic films include polyethylene terephthalate (PET) films, polyethylene films, and polypropylene films. As mentioned above, the second protective film 32 can 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 release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.

The second protective film preferably has a moisture permeability at 40°C and 92% RH of 30 g/m ² ·24h or less, more preferably 20 g/m ² ·24h or less, still more preferably 15 g/m ² · 24 hours or less. On the other hand, the moisture permeability of the second protective film at 40° C. and 92% RH is, for example, 1 g/m ² ·24 h or more.

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

A-6. Production of Laminate A laminate can be obtained by laminating at least the polarizing plate and the retardation layer.

The lamination of the polarizing plate and the retardation layer is performed, for example, while transporting them by roll (so-called roll-to-roll). Lamination is typically performed by transferring a liquid crystal alignment solidified layer formed on a substrate. As shown in FIG. 2, when the retardation layer has a laminated structure, each retardation layer may be sequentially laminated (transferred) to the polarizing plate, and the laminate of the retardation layers may be laminated (transferred) to the polarizing plate. may be transferred).

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 still more preferably 0.6 μm to 1.5 μm. In addition, for example, due to the adhesive used for lamination of the polarizing plate and the retardation layer (specifically, shrinkage during curing of the active energy ray-curable adhesive), lamination of the polarizing plate and the retardation layer Warping may occur later. The direction of the warpage that occurs after lamination of the polarizing plate and the retardation layer is, for example, convex toward the polarizing plate side. Warping tends to occur along the absorption axis direction of the polarizing plate 10 (polarizer 11).

Lamination of the polarizing plate and the retardation layer is preferably carried out in an environment where the amount of water vapor (A1) is 10.2 g/m ³ or less. The water vapor content (A1) in lamination is more preferably 6.0 g/m ³ to 10.0 g/m ³ , still more preferably 8.0 g/m ³ to 9.5 g/m ³ . By performing lamination in an environment in which the amount of water vapor (A1) is within such a range, for example, the effect of the humidification treatment described later becomes remarkable. Such a water vapor content (A1) in the lamination can be realized, for example, by changing the relative humidity depending on the temperature in the temperature range of 18°C to 25°C. The amount of water vapor (A1) can be achieved, for example, by setting the relative humidity to 65% RH or less when the temperature is 18 ° C.; For example, when the temperature is 23° C., it can be achieved by setting the relative humidity to 45% RH or less. In addition, the lower limit of the relative humidity can be, for example, 30% RH.

As described above, when the laminate further has the first protective film, the second protective film, the other functional layers (e.g., conductive layer, other retardation layer), these are at predetermined positions, optionally can be laminated or formed in any suitable manner.

In one embodiment, the laminate is obtained by laminating a polarizing plate and a retardation layer to prepare a laminate precursor, and laminating a first protective film and a second protective film on the obtained laminate precursor. can be obtained by

Lamination of the laminate precursor and the first protective film is performed, for example, by laminating the surface protective film. Lamination of the laminate precursor and the second protective film 32 is performed using, for example, an adhesive. The thickness of the adhesive (the thickness of the adhesive layer arranged between the retardation layer 20 and the second protective film 32) is, for example, 10 μm to 20 μm.

The laminate can be subjected to humidification treatment. By subjecting the laminate to a humidifying treatment, moisture is imparted to the laminate (preferably, the polarizer), and the warp that occurs after lamination of the polarizing plate and the retardation layer can be corrected. In addition, it is preferable that the laminated body to be packed is not warped at the time of packing, which will be described later.

The humidification treatment is performed, for example, by placing the laminate in an environment of 18° C. to 34° C. and 60% RH to 90% RH. The amount of water vapor (A2) during humidification is preferably 10.5 g/m ³ to 30 g/m ³ , more preferably 11 g/m ³ to 20 g/m ³ .

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.; can be achieved by setting the relative humidity to 60% RH or higher; and for example, when the temperature is 23° C., it can be achieved by setting the relative humidity to 50% RH or higher. In addition, the upper limit of the relative humidity may be, for example, 100% RH.

In one embodiment, the laminate is subjected to a humidification treatment in an environment that satisfies a water vapor content higher than the water vapor content (A1). More specifically, the difference between the amount of water vapor (A2) during the humidification process and the amount of water vapor (A1) is preferably 0.5 g/m ³ or more, more preferably 1.0 g/m ³ to 28 g. /m ³ , more preferably 1.0 g/m ³ to 12 g/m ³ , particularly preferably 1.5 g/m ³ to 10 g/m ³ , most preferably 1.5 g/m ³ to ⁸ g/m3. By humidifying under such conditions, an appropriate amount of moisture can be imparted to the laminate. More specifically, moisture can be applied to the laminate without shrinking the laminate. In the humidification treatment, if the amount of moisture applied to the laminate is too large, for example, warpage occurs in a direction opposite to the initial warp and/or in a direction orthogonal to the initial warp direction within the plane. Sometimes.

The moistening treatment time is preferably 6 hours or longer, more preferably 12 hours or longer, and still more preferably 18 hours or longer. On the other hand, the duration of the humidification process is, for example, 48 hours or less.

B. 3. Packing FIG. 3 is a schematic perspective view showing an example of a state in which the laminate is packed, and FIG. 4 is a cross-sectional view of the package shown in FIG. As illustrated, the laminate 100 is packed with a packing material 110 to obtain a package 200 . Specifically, the package 200 can be obtained by putting the laminate 100 inside a bag-like package 110 having an opening and then closing the opening. In the illustrated example, the laminated body is packed by closing the opening of the bag-shaped packing material 110 containing the laminated body 100, but the packing method is not limited to this. For example, the package may be obtained by wrapping the laminate with a sheet-like packing material.

As shown in the figure, a stack 102 in which a plurality of sheet-shaped laminates 100 are stacked is packed with a packing material 110 . Specifically, prior to packaging, the laminate is formed into sheets of a predetermined size. A sheet-shaped laminate is preferably obtained, for example, by cutting a long laminate or a laminate precursor. In the illustrated example, a sheet-shaped laminated body is packed, but for example, a long laminated body may be rolled up and packed.

The thermal conductivity of the packing material is 0.2 W/m·K or less, preferably 0.1 W/m·K or less, more preferably 0.06 W/m·K or less, and still more preferably It is 0.03 W/m·K or less. By using such a packing material, it is possible to reduce the influence of heat on the laminate and suppress the occurrence of warpage in the obtained polarizing plate with a retardation layer. On the other hand, the thermal conductivity of the packing material is, for example, 0.001 W/m·K or more.

A resin sheet is typically used as the packing material. Polyester sheets such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT) are preferably used as the resin sheet. Moreover, a laminated sheet obtained by laminating any suitable layer on a resin sheet may be used as the packing material. Examples of the layer laminated on the resin sheet include metal layers containing metals such as aluminum and copper, and oxide layers containing oxides such as aluminum oxide and silicon oxide.
The thickness of the packing material is, for example, 1 mm to 6 mm.

As shown in the figure, the inside of the package is preferably hermetically sealed from the viewpoint of more reliably suppressing the influence of heat.

The package can be stored for a predetermined period of time. A method for storing a polarizing plate with a retardation layer according to one embodiment of the present invention includes storing the package. By packing the laminate with a predetermined packing material, it is possible to suppress the occurrence of warping in the obtained polarizing plate with a retardation layer during storage (including transportation). Thus, the retardation layer-attached polarizing plate obtained according to the embodiment of the present invention can be satisfactorily laminated on, for example, an image display panel.

The weight loss per unit volume of the laminated portion of the polarizing plate and the retardation layer from before packing to after storage is preferably 0.2% or less, more preferably 0.1% or less. Such weight reduction can be achieved by suppressing the effects of heat using the predetermined packaging material. By setting the weight reduction within such a range, warping of the obtained polarizing plate with a retardation layer can be effectively suppressed.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. The thickness, thermal conductivity and moisture permeability are values measured by the following measuring methods. In addition, unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are by weight.
<Thickness>
The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name “JSM-7100F”). A thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name “KC-351C”).
<Thermal conductivity>
The thermal conductivity of the packing material was determined by the laser flash method. Specifically, the packing material is heated and the thermal diffusivity at 20 ° C.-70 ° C. is measured with a laser flash method thermal constant measurement device (manufactured by Advance Riko, product name “TC-1200RH”), and the specific heat and density are multiplied. The thermal conductivity of the packing material was calculated from the combined value.
<Moisture permeability>
The moisture permeability was determined by the moisture permeability cup method (JIS Z0208-1976).

[Example 1]
(Preparation of polarizing plate)
As a thermoplastic resin substrate, a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used, and one side of this resin substrate was subjected to corona treatment. .
Polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER") were mixed at a ratio of 9:1, and 100 parts by weight of PVA-based resin. was added with 13 parts by weight of potassium iodide and dissolved in water to prepare an aqueous PVA 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 having a thickness of 13 μm, thereby producing a laminate.
The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Then, the finally obtained polarizer is added to a dyeing bath (iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. It was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was a desired value (dyeing treatment).
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 40°C (an aqueous solution of boric acid 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). (crosslinking treatment).
After that, while immersing the laminate in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70° C., the laminate was moved vertically (longitudinally) between rolls with different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).
Thereafter, while drying in an oven maintained at about 90° C., it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75° C. (dry shrinkage treatment).
In this way, a polarizer having a thickness of about 5 μm was formed on the resin substrate to obtain a laminate having a structure of resin substrate/polarizer.

An HC-COP film (water vapor permeability at 40° C. and 92% RH: 30 g/m ² · 24 h, thickness: 27 μm) was placed on the polarizer side of the resulting laminate via an ultraviolet curable adhesive as a first protective layer. pasted together. The HC-COP film was a film in which an HC layer (2 μm thick) was formed on a cycloolefin resin (COP) film (25 μm thick), and the films were laminated so that the COP film was on the polarizer side. Then, the resin substrate was peeled off from the polarizer to obtain a polarizing plate having a structure of HC-COP film (first protective layer)/polarizer.

(Production of retardation layer)
Polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name “Paliocolor LC242”, represented by the following formula) 10 g, and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name “Irgacure 907 ”) was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth and subjected to orientation treatment. The direction of the orientation treatment was set to be 15° from the direction of the absorption axis of the polarizer when viewed from the viewing side when attached to the polarizing plate. The above liquid crystal coating solution was applied to the alignment-treated surface using a bar coater, and dried by heating at 90° C. for 2 minutes to align the liquid crystal compound. The liquid crystal layer thus formed is irradiated with light of 1 mJ/cm ² using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal alignment fixed layer A (H layer) on the PET film. did. The liquid crystal alignment fixed layer A had a thickness of 2.5 μm and an in-plane retardation Re (550) of 270 nm. Furthermore, the liquid crystal alignment fixed layer A exhibited refractive index characteristics of nx>ny=nz.

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

(Preparation of laminate)
The obtained liquid crystal alignment fixed layer A (H layer) and liquid crystal alignment fixed layer B (Q layer) were transferred in this order to the polarizer side of the obtained polarizing plate. At this time, the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment fixed layer A is 15°, and the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment fixed layer B is 75°. Transfer (bonding) was carried out in this manner. Each transfer was performed through an ultraviolet curable adhesive (thickness 1.0 μm). Thus, a laminate precursor was obtained. Note that the transfer (bonding) was carried out while being conveyed by rolls. Further, the transfer (bonding) was performed in an environment with a water vapor content of 9.3 g/m ³ (23° C. and 45% RH).
The obtained laminate precursor had a total thickness of 36 μm and a thickness ratio of 8. Further, the moisture permeability of the laminated portion from the liquid crystal alignment fixed layer A to the liquid crystal alignment fixed layer B at 40° C. and 92% RH was 500 g/m ² ·24 h.

Next, a surface protective film (thickness: 38 μm) was attached to the first protective layer side of the polarizing plate of the laminate precursor. The surface protection film is a PET film (thickness: 28 μm, moisture permeability: 20 g/m ² ·24 h) and an adhesive layer (thickness: 10 μm) formed thereon.
Furthermore, a separator (thickness 38 μm, moisture permeability 20 g / m ² · 24 h) is attached to the liquid crystal alignment fixed layer B (Q layer) side of the laminate precursor via an adhesive layer (thickness 15 μm), and the laminate got

The obtained long laminate was cut along a direction at 45° to the longitudinal direction and the width direction (direction orthogonal to the longitudinal direction) to obtain a sheet laminate of 144 mm x 73 mm. The longitudinal direction corresponds to the absorption axis direction of the polarizer.
Similarly, a total of 200 sheet laminates of 144 mm×73 mm were produced.

(Humidification treatment)
Humidification treatment was applied to 200 sheets of the obtained sheet-shaped laminate. The humidification treatment was performed at 23° C. and 60% RH (water vapor content of 12.4 g/m ³ ) for 24 hours.

(packing)
After putting 200 sheets of the laminate after humidification treatment inside a bag-shaped packing material (PET sheet, thermal conductivity 0.01 to 0.03%, thickness 4 mm) having an opening, the opening of the packing material. closed to obtain a package.

The obtained package was stored in an environment of 40° C. for 10 hours. Thus, a polarizing plate with a retardation layer was obtained.

[Example 2]
In the same manner as in Example 1, except that a polarizing plate was obtained by the method described below, and a retardation layer was laminated on the second protective layer side of the obtained polarizing plate to obtain a laminate. A polarizing plate with a retardation layer was obtained.

(Preparation of polarizing plate)
A long roll of polyvinyl alcohol (PVA)-based resin film with a thickness of 30 μm (manufactured by Kuraray, product name “PE3000”) is uniaxially stretched in the longitudinal direction by a roll stretching machine so as to be 5.9 times the length while simultaneously being stretched. After swelling, dyeing, cross-linking and washing treatments were performed in this order, a drying treatment was finally performed to produce a polarizer having a thickness of 12 μm.
In the swelling treatment, the film was stretched 2.2 times while being treated with pure water at 20°C. Next, the dyeing treatment is performed in an aqueous solution at 30° C. in which the weight ratio of iodine and potassium iodide is 1:7 and the iodine concentration is adjusted so that the single transmittance of the resulting polarizer is 45.0%. while stretching to 1.4 times. Then, the cross-linking treatment employed two-step cross-linking treatment, and the first-step cross-linking treatment was performed by stretching the film 1.2 times while treating it in an aqueous solution of boric acid and potassium iodide at 40°C. The boric acid content of the aqueous solution for the first-stage cross-linking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. In the second-stage cross-linking treatment, the film was stretched 1.6 times while being treated in an aqueous solution of boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution for the second-stage cross-linking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight. Then, the washing treatment was carried out with an aqueous potassium iodide solution at 20°C. The potassium iodide content of the aqueous solution for the cleaning treatment was 2.6% by weight. Finally, a drying treatment was performed at 70° C. for 5 minutes to obtain a polarizer.

An HC-COP film (water vapor permeability at 40° C. and 92% RH: 20 g/m ² ·24 h, thickness: 29 μm) was attached as a first protective layer to one side of the polarizer. The HC-COP film is a film in which an HC layer (thickness 3 μm) is formed on a cycloolefin resin (COP) film (thickness 26 μm). Then, on the other side of the polarizer, a TAC film (thickness: 20 μm) with Re(550) of 0 nm was attached as a second protective layer. Thus, a polarizing plate having a structure of HC-COP film (first protective layer)/polarizer/TAC film (second protective layer) was obtained.

The moisture permeability at 40° C. and 92% RH of the laminated portion from the TAC film to the liquid crystal alignment fixed layer B was 600 g/m ² ·24 h.

[Comparative Example 1]
Polarized light with a retardation layer in the same manner as in Example 1 except that a bag-shaped packing material having an opening (polyethylene sheet, thermal conductivity 0.3 to 0.4%, thickness 500 μm) was used for packing. got a board

[Comparative Example 2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the laminate was not packed.

[Reference example 1]
HC-TAC film (water vapor transmission rate 600 g/m ² 24 h at 40° C. and 92% RH, thickness 32 μm) was used as the first protective layer in place of the HC-COP film in the production of the polarizing plate; A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the body was not packed. Note that the HC-TAC film is a film in which an HC layer (7 μm thick) is formed on a TAC film (25 μm thick), and the films were laminated so that the TAC film was on the polarizer side.

[Reference example 2]
HC-TAC film (water vapor transmission rate 600 g/m ² 24 h at 40° C. and 92% RH, thickness 32 μm) was used as the first protective layer in place of the HC-COP film in the production of the polarizing plate; A polarizing plate with a retardation layer was obtained in the same manner as in Example 2, except that the body was not packed. Note that the HC-TAC film is a film in which an HC layer (7 μm thick) is formed on a TAC film (25 μm thick), and the films were laminated so that the TAC film was on the polarizer side.

The examples and comparative examples were evaluated as follows. The evaluation results are summarized in Table 1.
<Evaluation>
1. Amount of Change in Warpage In the examples and comparative examples, the laminate and the polarizing plate with the retardation layer before storage (packing) were used as test pieces. When the test piece was placed on a flat surface with the retardation layer side facing the flat surface, the height of the highest portion from the flat surface was measured to determine the amount of warpage. Here, the case where the warpage was convex toward the stationary surface was indicated as "positive (+)", and the case where the curvature was convex toward the side opposite to the stationary surface was indicated as "negative (-)".
Next, the difference (amount of change in warpage) between the warpage amount of the retardation layer-attached polarizing plate and the warpage amount of the laminate before storage (packing) was determined. The values shown in Table 1 are average values of 12 sheets.
2. Weight change per unit volume of laminated portion of polarizing plate and retardation layer And the weight of the separator (including the adhesive layer) was measured, and the weight change (%) was calculated by the following formula. The values shown in Table 1 are the minimum and maximum values of the measured samples.
(Weight of laminate before storage - Weight of polarizing plate with retardation layer) / (Weight of laminate before storage - Weight of surface protective film and separator (including adhesive layer)) x 100

In the example, warpage is suppressed. It should be noted that the direction of warpage changed in the (-) direction due to storage.
In Reference Examples 1 and 2, substantially no change in warpage was observed before and after storage.

A retardation layer-attached polarizing plate according to one embodiment of the present invention is used as a retardation layer-attached polarizing plate of an image display device, and in particular, a curved, bendable, foldable, or windable image display device. can be suitably used for Typical image display devices include liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

10 polarizing plate 11 polarizer 12 first protective layer 13 second protective layer 20 retardation layer 21 first retardation layer 22 second retardation layer 100 laminate 110 packing material 200 package

Claims (14)

A polarizing plate including a polarizer having a first principal surface and a second principal surface facing each other and a first protective layer disposed on the first principal surface side of the polarizer; and the second principal surface of the polarizer. preparing a laminate having a retardation layer disposed on the face side;
obtaining a package by packing the laminate with a packing material having a thermal conductivity of 0.2 W/m·K or less;
storing the package;
The difference in moisture permeability at 40° C. and 92% RH between the laminated portion from the layer arranged adjacent to the second main surface of the polarizer to the retardation layer and the first protective layer is 350 g / m 2.24 hours or ^more ,
A method for producing a polarizing plate with a retardation layer. The manufacturing method according to claim 1, wherein the first protective layer has a moisture permeability at 40°C and 92% RH of 100 g/ ^m2 ·24h or less. The manufacturing method according to claim 1 or 2, wherein the laminated portion has a moisture permeability of 400 g/m ² ·24 h or more at 40°C and 92% RH. 4. The manufacturing method according to any one of claims 1 to 3, wherein the polarizing plate has a second protective layer arranged between the polarizer and the retardation layer. 5. The manufacturing method according to any one of claims 1 to 4, wherein the retardation layer is an alignment fixed layer of a liquid crystal compound. The manufacturing method according to any one of claims 1 to 5, wherein the retardation layer has a laminated structure of two or more layers. The manufacturing method according to any one of claims 1 to 6, wherein the laminate has a first protective film, the polarizing plate, the retardation layer, and a second protective film in this order. The manufacturing method according to claim 7, wherein the first protective film has a moisture permeability of 30 g/m ² ·24 h or less at 40°C and 92% RH. The manufacturing method according to claim 7 or 8, wherein the second protective film has a moisture permeability at 40°C and 92% RH of 30 g/m ² ·24 h or less. The manufacturing method according to any one of claims 1 to 9, wherein the sheet-shaped laminate is packed to obtain the package. 11. The manufacturing method according to any one of claims 1 to 10, wherein the sum of the thickness of said polarizing plate and the thickness of said retardation layer is 83 [mu]m or less. 12. The manufacturing method according to any one of claims 1 to 11, comprising laminating the polarizing plate and the retardation layer using an active energy ray-curable adhesive. 13. The manufacturing method according to any one of claims 1 to 12, comprising subjecting the laminate to a humidifying treatment before the packaging. A polarizing plate including a polarizer having a first principal surface and a second principal surface facing each other and a first protective layer disposed on the first principal surface side of the polarizer; and the second principal surface of the polarizer. preparing a laminate having a retardation layer disposed on the face side;
obtaining a package by packing the laminate with a packing material having a thermal conductivity of 0.2 W/m·K or less;
storing the package;
The difference in moisture permeability at 40° C. and 92% RH between the laminated portion from the layer arranged adjacent to the second main surface of the polarizer to the retardation layer and the first protective layer is 350 g / m 2.24 hours or ^more ,
A method for storing a polarizing plate with a retardation layer.

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