KR20220135162A - Polarizing plate and method for manufacturing polarizing plate - Google Patents

Abstract

An object of the present invention is to provide a warp-stabilized polarizing plate. According to an embodiment of the present invention, the polarizing plate includes: a first protective layer having a moisture permeability of 40 g/m2 24h at 40℃ and 92%RH, a polarizer, and a second protective layer having a moisture permeability of 350 g/m2 24h at 40℃ and 92%RH, arranged in the described order, and a light absorbance measured by an infrared moisture meter is 0.0100 or more and 0.0155 or less.

Description

A polarizing plate and the manufacturing method of a polarizing plate

The present invention relates to a polarizing plate and a method for manufacturing a polarizing plate.

BACKGROUND ART 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. A polarizing plate is typically used for an image display panel mounted on an image display apparatus. 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). However, there is a problem in that the polarizing plate is prone to warpage, and the direction and degree of the warpage are likely to change depending on the environment in which it is placed. This warpage and a change in warpage can cause, for example, a manufacturing defect of the image display device.

Japanese Patent No. 3325560 Publication

The present invention has been made in order to solve the above conventional problems, and its main object is to obtain a polarizing plate in which the state of warpage is stabilized.

According to an embodiment of the present invention, a polarizing plate is provided. This polarizing plate has a first protective layer having a water vapor transmission rate of 40 g/m 2 ·24h or less at 40°C and 92%RH, a polarizer, and a second protective layer having a water vapor transmission rate of 350 g/m2·24h or more at 40°C and 92%RH. is in this order, and the absorbance by infrared moisture meter measurement is 0.0100 or more and 0.0155 or less.

In one embodiment, the said 1st protective layer contains a cycloolefin resin.

In one embodiment, the said 2nd protective layer contains a cellulosic resin.

According to another embodiment of the present invention, a polarizing plate with a retardation layer is provided. This polarizing plate with a retardation layer has the said polarizing plate and the retardation layer arrange|positioned at the said 2nd protective layer side of the said polarizing plate.

In one embodiment, the phase difference layer is an alignment-solidified layer of a liquid crystal compound.

According to another embodiment of the present invention, a method for manufacturing a polarizing plate is provided. This manufacturing method is a 1st protective layer whose water vapor transmission rate is 40 g/m<2>*24h or less in 40 degreeC and 92%RH, a polarizer, and a 2nd protection whose water vapor transmission rate in 40 degreeC and 92%RH is 350 g/m<2>24h or more. A polarizing plate having an absorbance of 0.0100 or more and 0.0155 or less by infrared moisture meter measurement is obtained, including preparing a laminate having the layers in this order and subjecting the laminate to a humidity control treatment.

In one embodiment, the said humidity control process is performed in the state in which the main surface of one side of the said 2nd protective layer was exposed.

According to still another embodiment of the present invention, a method for manufacturing a polarizing plate with a retardation layer is provided. This manufacturing method includes laminating|stacking a retardation layer on the said 2nd protective layer side of the polarizing plate obtained by the said manufacturing method.

(Effects of the Invention)

According to the embodiment of the present invention, it is possible to obtain a polarizing plate in which a state of warpage is stabilized by satisfying a predetermined absorbance.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the outline structure of the polarizing plate with retardation layer by one Embodiment of this invention.
2 is a cross-sectional view showing an example of the laminate before being subjected to humidity control treatment.
It is sectional drawing which shows an example of the state of the curvature of a polarizing plate.
4 is a schematic cross-sectional view showing the outline of an image display panel according to one embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)

Definitions of terms and symbols in the present 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 (ie, slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, fast axis direction), and "nz" is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re(λ)" is an 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 the light of wavelength 550nm in 23 degreeC. Re(λ) is obtained by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm).

(3) retardation in thickness direction (Rth)

"Rth(λ)" is the retardation in the thickness direction measured with the light of the wavelength λnm in 23 degreeC. For example, "Rth(550)" is the phase difference in the thickness direction measured with the light of wavelength 550nm in 23 degreeC. Rth(λ) is obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm).

(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 a clockwise direction and a counterclockwise direction with respect to the reference direction. Accordingly, for example, “45°” means ±45°.

A. Polarizing plate with retardation layer

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the outline structure of the polarizing plate with retardation layer by one Embodiment of this invention. The polarizing plate 100 with a retardation layer has the polarizing plate 10, the retardation layer 20, and the protective film 30 in this order. The polarizer 11 has a first main surface 11a and a second main surface 11b that are opposed to each other, and a first protective layer 12 is formed on the first main surface 11a side (typically the viewer side) of the polarizer 11 . ) is disposed, and the second protective layer 13 is disposed on the second main surface 11b side of the polarizer 11 . Specifically, the polarizing plate 10 includes a polarizer 11 , a first protective layer 12 disposed on one side of the polarizer 11 (a side on which the retardation layer 20 is not disposed), and the polarizer 11 . and a second protective layer 13 disposed on the other side (between the polarizer 11 and the retardation layer 20). The retardation layer 20 has a stacked structure including the first retardation layer 21 and the second retardation layer 22 .

In the illustrated example, the retardation layer 20 has a stacked structure including the first retardation layer 21 and the second retardation layer 22, but it is different from the illustrated example, and the retardation layer 20 has a stacked structure of three or more layers. may have, or may be a single layer.

Although not shown in figure, the polarizing plate with a retardation layer may have another functional layer further. The type, characteristic, number, combination, arrangement, and the like of the functional layers that the polarizing plate with a retardation layer may have may be appropriately set according to the purpose. For example, the polarizing plate with a retardation layer may further have an isotropic base material with a conductive layer or a conductive layer. A polarizing plate with a retardation layer which has a conductive layer or an isotropic base material with a conductive layer is applied to the so-called inner touch panel type input display device in which a touch sensor was mounted inside an image display panel, for example. As another example, the polarizing plate with a retardation layer may further have another retardation layer. Other optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement, and the like of the retardation layer may be appropriately set according to the purpose. As a specific example, on the viewing side of the polarizer, other retardation layers that improve visibility when viewed through polarized sunglasses (typically, a layer imparting a (elliptic) circular polarization function, a layer imparting an ultra-high phase difference) are formed good night. By having such a layer, excellent visibility can be realized even when the display screen is visually viewed through a polarizing lens such as polarized sunglasses. Therefore, a polarizing plate with a retardation layer having such a layer can be suitably applied also to an image display device that can be used outdoors.

Each member constituting the retardation layer polarizing plate may be laminated via any suitable adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. Specifically, the retardation layer 20 may be bonded to the second protective layer 13 via an adhesive layer (preferably using an active energy ray-curable adhesive), or via an adhesive layer (eg, an acrylic adhesive). It may be joined to the second protective layer 13 . As shown, when the retardation layer 20 has a laminated structure of two or more layers, the retardation layers are bonded to each other through, for example, an adhesive layer (preferably using an active energy ray-curable adhesive).

For example, the protective film 30 is bonded to the retardation layer 20 through an adhesive layer. Practically, this pressure-sensitive adhesive layer allows the polarizing plate 100 with a retardation layer to be attached to the image display panel main body. The protective film 30 may function as a release film (separator) that is temporarily attached until the polarizing plate 100 with a retardation layer is provided for use. By temporarily affixing a protective film, while protecting an adhesive layer, for example, roll formation of a polarizing plate with retardation layer becomes possible.

The shape of a long picture may be sufficient as a polarizing plate with retardation layer, and single-leaf shape may be sufficient as it. Here, "long shape" refers to an elongated shape having a sufficiently long length with respect to the width, and for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width. The long phase difference layer polarizing plate can be wound in roll shape.

A-1. Polarizer

The polarizing plate includes a polarizer, a first passivation layer, and a second passivation layer. The thickness of a polarizing plate becomes like this. Preferably it is 20 micrometers or more, More preferably, it is 25 micrometers or more. On the other hand, the thickness of a polarizing plate becomes like this. Preferably it is 70 micrometers or less, More preferably, it is 65 micrometers or less. In addition, when an adhesive layer is used when laminating a polarizer and a protective layer in the thickness of a polarizing plate, the thickness is not included.

The absorbance of the polarizing plate 10 (the laminated portion from the first protective layer 12 to the second protective layer 13) measured by an infrared moisture meter is 0.0100 or more, preferably 0.0105 or more. On the other hand, the absorbance of the polarizing plate 10 is 0.0155 or less, preferably 0.0150 or less. By satisfying such absorbance, it is possible to obtain a polarizing plate in which the state of warpage is stabilized.

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

The thickness of a polarizer becomes like this. Preferably it is 18 micrometers or less, More preferably, it is 15 micrometers or less, More preferably, it is 12 micrometers 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%, and more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

The protective layer may be formed of any suitable film that can be used as a protective layer of a polarizer. Specific examples of the material used as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, and polysulfone. Transparent resins, such as a cycloolefin type, such as a phone type|system|group, a polystyrene type, and polynorbornene, a polyolefin type, (meth)acrylic type, and an acetate type, are mentioned.

The polarizing plate with a retardation layer which concerns on embodiment of this invention is arrange|positioned typically on the visual recognition side of an image display apparatus, and the 1st protective layer 12 is arrange|positioned on the visual recognition side. Accordingly, the first protective layer 12 may be subjected to a surface treatment such as a hard coat (HC) treatment, an antireflection treatment, an antistick treatment, or an antiglare treatment, if necessary.

The thickness of the protective layer is preferably 5 µm to 80 µm, more preferably 10 µm to 40 µm, and still more preferably 15 µm to 35 µm. In addition, when the surface treatment is performed, the thickness of the first protective layer 12 includes the thickness of the surface treatment layer.

The second protective layer 13 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 still more preferably 10 μm to 30 μm. .

In one embodiment, the moisture permeability of the first protective layer 12 at 40°C and 92%RH is 40 g/m 2 ·24h or less, and the second protective layer 13 at 40°C and 92%RH. of 350 g/m 2 ·24 h or more. According to this form, the absorbance can be satisfactorily achieved. Specifically, moisture can be absorbed by the polarizer 11 from the second protective layer 13 side by a humidity control treatment described later, and the moisture introduced into the polarizer 11 (polarizing plate 10) is converted into the first protective layer 12 . It can be prevented from being emitted from the side. In addition, since the polarizer 11 may have excellent water absorption (water holding capacity), it is difficult to miss moisture once introduced into the polarizer 11 .

The water vapor transmission rate of the first protective layer 12 at 40°C and 92%RH is preferably 30 g/m 2 ·24 h or less, and more preferably 20 g/m 2 ·24 h or less. On the other hand, the water vapor transmission rate of the 1st protective layer 12 at 40 degreeC and 92%RH is 1 g/m<2>*24h or more, for example. Examples of the constituent material of the first protective layer 12 include cycloolefin-based resins and polyester-based resins. In addition, when the surface treatment is performed, the moisture permeability of the first protective layer 12 is measured including the surface treatment layer.

Preferably the moisture permeability in 40 degreeC and 92%RH of the 2nd protective layer 13 is 500 g/m<2>*24h or more, More preferably, it is 600 g/m<2>*24h or more. On the other hand, the water vapor transmission rate of the 2nd protective layer 13 at 40 degreeC and 92%RH is 1200 g/m<2>*24h or less, for example. Examples of the constituent material of the second protective layer 13 include cellulose-based resins such as TAC, polycarbonate-based resins, and (meth)acrylic-based resins.

The polarizing plate may be manufactured by any suitable method. Specifically, the polarizing plate may contain the polarizer produced with the single-layered resin film, and may contain the polarizer obtained using the laminated body of two or more layers.

The method of manufacturing a polarizer from the said single-layered resin film typically includes performing the dyeing process and extending|stretching process with dichroic substances, such as iodine and a dichroic dye, to a resin film. As the resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene/vinyl acetate copolymer-based film is used. The method may further include an insolubilization treatment, a swelling treatment, a crosslinking treatment, and the like. A polarizing plate can be obtained by laminating|stacking a protective layer on at least one side of the obtained polarizer. Since such a manufacturing method is well-known and common in the art, a detailed description will be omitted.

The polarizer obtained using the said laminated body can be produced using, for example, a laminated body of a resin base material, a resin film, or a resin layer (typically a PVA-type resin layer). Specifically, a PVA-based resin solution is applied to a resin substrate, dried to form a PVA-based resin layer on the resin substrate, and a laminate of a resin substrate and a PVA-based resin layer is obtained; It can be produced by extending|stretching and dyeing the said laminated body, and making a PVA-type resin layer into a polarizer. In this embodiment, Preferably, the PVA-type resin layer containing a halide and PVA-type resin is provided on one side of a resin base material. Stretching typically includes stretching by immersing the laminate in an aqueous boric acid solution. In addition, the stretching may further include aerial stretching of the laminate at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution if necessary. Further, in the present embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is shrunk by 2% or more in the width direction by heating while being conveyed in the longitudinal direction. Typically, the manufacturing method of this embodiment includes performing an aerial auxiliary stretching process, a dyeing|staining process, an underwater extending|stretching process, and a drying shrinkage process to a laminated body in this order. By introducing auxiliary stretching, even when PVA is applied on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA, and high optical properties can be achieved. Moreover, by raising the orientation of PVA in advance at the same time, when it is immersed in water in a subsequent dyeing process or an extending process, problems, such as a fall and dissolution of the orientation of PVA, can be prevented, and high optical characteristic can be achieved. In addition, when the PVA-based resin layer is immersed in a liquid, as compared to the case where the PVA-based resin layer does not contain a halide, the disorder of the orientation of the PVA molecules and the decrease in the orientation can be suppressed, and high optical properties can be achieved. can In addition, high optical properties can be achieved 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 on the peeling surface where the resin substrate is peeled from the resin substrate/polarizer laminate, or on the side opposite to the peeling surface You may use it by laminating|stacking any suitable protective layer according to the purpose on the surface of. The detail of the manufacturing method of such a polarizer is described in Unexamined-Japanese-Patent No. 2012-73580, and patent 6470455, for example. These publications are incorporated herein by reference in their entirety.

A polarizing plate that satisfies the predetermined absorbance can be obtained by, for example, preparing a laminate of a first protective layer, a polarizer, and a second protective layer, and subjecting the laminate to a humidity control treatment (typically, a humidification treatment). can The light absorbency (moisture content) of the polarizing plate obtained by performing a humidity control process on such a laminated body (for example, in the state before laminating|stacking a retardation layer) is possible easily. Specifically, it can be easily controlled so that the polarizer can have an equilibrium moisture content by efficiently absorbing moisture to the polarizer. In one embodiment, the polarizing plate which satisfies the desired light absorbency (moisture content) is obtained by adjusting the conditions of a humidity control process according to the light absorbency (moisture content) of a laminated material. In addition, an equilibrium moisture content is a constant temperature, and in the atmosphere of a constant humidity, it means the weight fraction of water when it is left to stand until the change of a moisture content substantially disappears.

2 is a cross-sectional view showing an example of the laminate before being subjected to humidity control treatment. The laminate 90 has a first protective layer 12 , a polarizer 11 , a second protective layer 13 , and a surface protective film 40 in this order. The surface protection film 40 typically includes a base material (not shown) and an adhesive layer formed on one side of the base material, and is bonded to the main surface 13a of the second protective layer 13 so as to be peelable. The base material of the surface protection film 40 is comprised from polyester-type polymers, such as polyethylene terephthalate (PET), for example. The thickness of the surface protection film 40 is 30 micrometers - 100 micrometers, for example.

Although not shown, the surface protection film 40 is peeled off and the main surface 13a of one side of the second protective layer 13 (the side where the polarizer 11 is not disposed) is exposed to humidity with respect to the laminate 90 . It is preferable to perform a treatment. According to this form, the absorbance can be satisfactorily achieved. Specifically, in the humidity control treatment, the polarizer 11 can efficiently absorb moisture (diffuse moisture) from the second protective layer 13 side, and the time for the humidity control treatment can be shortened.

It is preferable to perform the said humidity control process by putting a laminated material under the environment of 23 degreeC - 40 degreeC and 60%RH - 95%RH. For example, when temperature is 23 degreeC, it carries out by setting a relative humidity in the environment of 60 %RH or more. In addition, when the temperature is 35 degreeC, for example, it carries out by setting a relative humidity in the environment of 60 %RH or more. In addition, when the temperature is 40 degreeC, for example, it carries out by setting a relative humidity in the environment of 60 %RH or more. According to the humidity control treatment in such an environment, after the humidity control treatment in which the deteriorated polarizing plate is obtained, problems such as dew condensation occurring on the polarizing plate and causing poor appearance can be suppressed. In addition, the upper limit of the relative humidity may be, for example, 100%RH.

The amount of water vapor in the humidity control treatment is preferably 12 g/m 3 to 49 g/m 3 and more preferably 16 g/m 3 to 40 g/m 3 .

The time of the humidity control process becomes like this. Preferably it is 2 minutes - 25 minutes, More preferably, it is 17 minutes or less. The humidity control treatment with the laminate can be achieved in a short time.

After the humidity control treatment, a retardation layer may be laminated on the main surface 13a of one side of the second protective layer 13 . Before laminating a retardation layer, it is preferable to bond a surface protection film back to the exposed surface 13a of the 2nd protective layer 13 in a peelable state. According to this form, the moisture contained in the second protective layer 13 can be efficiently diffused into the polarizer 11 . In addition, it is possible to prevent the moisture introduced into the polarizing plate 10 from being released from the second protective layer 13 side. As described above, the polarizer 11 has a high absorptivity and may be higher than the absorptivity of the first passivation layer 12 and the second passivation layer 13 . Accordingly, moisture introduced into the polarizer 10 may mainly exist in the polarizer 11 .

It is preferable that the moisture permeability in 40 degreeC and 92%RH of the surface protection film joined after a humidity control process is 40 g/m<2>*24h or less, More preferably, it is 20 g/m<2>*24h or less. On the other hand, the water vapor transmission rate in 40 degreeC and 92%RH of a surface protection film is 7 g/m<2>*24h or more, for example.

Warp may occur in the resulting polarizing plate (laminate after humidity control treatment). It is sectional drawing which shows an example of the state of the curvature of a polarizing plate. In addition, in FIG. 3, hatching is abbreviate|omitted in the cross section of a polarizing plate in order to make drawing easy to read. In the example shown in FIG. 3, the convex curvature generate|occur|produced in the 2nd protective layer 13 side in the polarizing plate 10. As shown in FIG. Warpage tends to occur along the absorption axis direction of the polarizing plate 10 (polarizer 11). Even if the curvature generate|occur|produced in the polarizing plate (even if there exists nonuniformity in the curvature which generate|occur|produced), the curvature which generate|occur|produced in the polarizing plate at the time of lamination|stacking of the retardation layer etc. mentioned later can be corrected, for example. As a result, a polarizing plate with a retardation layer can be manufactured with good yield.

A-2. retardation layer

The thickness of the retardation layer is preferably 10 µm or less, more preferably 8 µm or less, and still more preferably 7 µm or less, although depending on the configuration (single layer or having a laminated structure). On the other hand, the thickness of the retardation layer is, for example, 1 µm or more. In addition, when the retardation layer has a laminated structure, "thickness of the retardation layer" means the sum of the thicknesses of each retardation layer. Specifically, the "thickness of the retardation layer" does not include the thickness of the adhesive layer.

As said retardation layer, Preferably the alignment-solidified layer (liquid crystal alignment-solidified layer) of a liquid crystal compound is used. By using the liquid crystal compound, for example, the difference between nx and ny of the obtained retardation layer can be made significantly larger than that of a non-liquid crystal material, so that the thickness of the retardation layer for obtaining a desired in-plane retardation can be made particularly small. Therefore, remarkable thickness reduction of the polarizing plate with a retardation layer can be implement|achieved. In this specification, the "alignment-solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer, and the alignment state is fixed. In addition, an "orientation-solidified layer" is a concept including the orientation hardening layer obtained by hardening a liquid crystal monomer so that it may mention later. In the retardation layer, the rod-shaped liquid crystal compounds are typically oriented in a state in which they are aligned in the slow axis direction of the retardation layer (homogeneous alignment).

The liquid crystal alignment solidification layer performs an alignment treatment on the surface of a predetermined substrate, and applies 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 fix the alignment state It can be formed by Any suitable alignment treatment may be employed as the alignment treatment. Specifically, a mechanical orientation process, a physical orientation process, and a chemical orientation process are mentioned. A rubbing process and an extending|stretching process are mentioned as a specific example of a mechanical orientation process. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. As a specific example of a chemical orientation process, an oblique vapor deposition method and a photo-alignment process are mentioned. As for the processing conditions of various orientation treatments, any suitable conditions may be employ|adopted according to the objective.

The alignment of the liquid crystal compound is performed by treatment at a temperature exhibiting a liquid crystal phase depending on the kind of the liquid crystal compound. By performing such a temperature treatment, a liquid crystal compound takes a liquid crystal state, and the said liquid crystal compound orientates according to the orientation treatment direction of the surface of a base material.

Fixation of an orientation state is performed by cooling the liquid crystal compound orientated as mentioned above in one Embodiment. 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.

The specific example of a liquid crystal compound and the detail of the formation method of an alignment-solidified layer are described in Unexamined-Japanese-Patent No. 2006-163343. The disclosure of the above publication is incorporated herein by reference.

A single layer may be sufficient as the retardation layer as mentioned above, and it may have a laminated structure of two or more layers.

Different from the illustrated example, in one embodiment when 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, and still more preferably 110 nm to 160 nm. The thickness of the retardation layer can be adjusted so that a desired in-plane retardation of the λ/4 plate is obtained. When a phase difference layer is the above-mentioned liquid-crystal orientation solidification layer, the thickness is 1.0 micrometer - 2.5 micrometers, for example. 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 still more preferably 44° to 46°. . In addition, the retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light.

In another embodiment when the retardation layer is a single layer, the retardation layer can function as a λ/2 plate. Specifically, Re(550) of the retardation layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and still more preferably 230 nm to 280 nm. The thickness of the retardation layer can be adjusted so that a desired in-plane retardation of the λ/2 plate is obtained. When retardation layer is the above-mentioned liquid-crystal orientation solidification layer, the thickness is 2.0 micrometers - 4.0 micrometers, for example. 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 still more preferably 12° to 16°. .

As shown, in one embodiment when the retardation layer 20 has a laminated structure, the retardation layer 20 is the first retardation layer (H layer) 21 and the second in order from the polarizing plate 10 side. It has a laminated structure of two layers in which the retardation layer (Q layer) 22 is arrange|positioned. The H layer may typically function as a λ/2 plate, and the Q layer may 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, further preferably 230 nm to 280 nm; Re (550) of the Q layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and still more preferably 110 nm to 150 nm. The thickness of the H layer can be adjusted so that a desired in-plane retardation of the λ/2 plate is obtained. When H layer is the above-mentioned liquid-crystal orientation solidification layer, the thickness is 2.0 micrometers - 4.0 micrometers, for example. The thickness of the Q layer can be adjusted so that a desired in-plane retardation of the λ/4 plate is obtained. When Q layer is the said liquid-crystal orientation solidification layer, the thickness is 1.0 micrometer - 2.5 micrometers, for example. 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°, still 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 still more preferably 72° to 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 may be opposite. In addition, each layer (for example, H layer and Q layer) may exhibit an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light, and a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light. , or a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light may be exhibited.

The retardation layer (at least one layer in the case of having a laminated structure) typically exhibits a relationship of refractive index characteristics of nx>ny=nz. In addition, "ny=nz" includes not only the case where ny and nz are completely identical but also the case where they are substantially identical. Therefore, there may be a case where ny>nz or ny<nz is not impaired in the effect 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 solidification layer. As said liquid crystal compound, the liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase is mentioned, for example. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystalline expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic. A liquid crystal polymer and a liquid crystal monomer may be used independently, respectively, and may be combined.

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 crosslinking (ie, curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, when the liquid crystal monomers are polymerized or crosslinked, the alignment state can be fixed by this. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the formed retardation layer, for example, transition to a liquid crystal phase, a glass phase, and a crystalline phase by the temperature change peculiar to a liquid crystalline compound does not occur. As a result, the retardation layer is not affected by temperature changes and becomes a very excellent retardation layer.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs 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 suitable liquid crystal monomer may be employed as the liquid crystal monomer. For example, described in Japanese Patent Publication Nos. 2002-533742 (WO 00/37585), EP 358208 (US 5211877), EP 66137 (US 4388453), WO 93/22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445, etc. A polymerizable mesogenic compound or the like can be used. As a specific example of such a polymerizable mesogenic compound, BASF Japan Ltd. brand name LC242, Merck company brand name E7, Wacker-Chem company brand name LC-Sillicon-CC3767 are mentioned, for example. As the liquid crystal monomer, a nematic liquid crystal monomer is preferable.

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 so-called retardation layer 22) having a refractive index characteristic showing a relationship of nz>nx=ny. positive C plate). Details of the λ/4 plate are as described above. In this 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°, further preferably 44° to 46°. is °. In addition, the first retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light.

The retardation Rth (550) in the thickness direction of the positive C plate is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, further preferably -90 nm to -200 nm and particularly preferably -100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly the same but also the case where nx and ny are substantially the same. The in-plane retardation Re(550) of the positive C plate is, for example, less than 10 nm.

The second retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material, but preferably consists of a film comprising a liquid crystal material fixed in homeotropic orientation. The 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 described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642 and a method for forming the retardation layer. In this case, the thickness of the second retardation layer is preferably 0.5 µm to 5 µm.

A-3. protective film

Protective film 30 may be comprised of any suitable plastic film. Specific examples of the plastic film include a polyethylene terephthalate (PET) film, a polyethylene film, and a polypropylene film. As described above, the protective film 30 may function as a separator. Specifically, as the protective film 30, a plastic film whose surface is coated with a release agent is preferably used. Specific examples of the release agent include a silicone-based release agent, a fluorine-based release agent, and a long-chain alkyl acrylate-based release agent.

It is preferable that the moisture permeability in 40 degreeC and 92%RH of a protective film is 40 g/m<2>*24h or less, More preferably, it is 20 g/m<2>*24h or less. On the other hand, the moisture permeability in 40 degreeC and 92 %RH of a protective film is 4 g/m<2>*24h or more, for example.

The thickness of a protective film becomes like this. Preferably they are 20 micrometers - 80 micrometers, More preferably, they are 35 micrometers - 55 micrometers.

A-4. Preparation of polarizing plate with retardation layer

The polarizing plate with a retardation layer which concerns on embodiment of this invention can be obtained by laminating|stacking the said polarizing plate and the said retardation layer.

Lamination|stacking of a polarizing plate and retardation layer is performed, for example, roll conveying these (a so-called roll-to-roll method). Lamination|stacking is typically performed by transferring the liquid-crystal orientation solidification layer formed in the base material. As shown in the figure, when the retardation layer has a laminated structure, each retardation layer may be sequentially laminated (transferred) to a polarizing plate, or a laminate in which retardation layers are laminated in advance may be laminated (transferred) to a polarizing plate.

In one embodiment, the said transcription|transfer is performed using an active energy ray hardening-type adhesive agent. The thickness (thickness of an adhesive layer) after hardening of an active energy ray hardening-type adhesive agent becomes like this. Preferably they are 0.4 micrometers or more, More preferably, they are 0.4 micrometers - 3.0 micrometers, More preferably, they are 0.6 micrometers - 1.5 micrometers. In another embodiment, the said transcription|transfer is performed using an adhesive. The thickness of the pressure-sensitive adhesive layer formed between the polarizing plate and the retardation layer is preferably 1 µm or more, more preferably 1 µm to 10 µm, and still more preferably 2 µm to 8 µm.

As described above, when the polarizing plate with a retardation layer further has the protective film and other functional layers (eg, conductive layer, other retardation layer), they may be laminated or formed at a predetermined position by any suitable method. . For example, the protective film 30 is laminated using an adhesive on the retardation layer 20 side of the laminate obtained by laminating the polarizing plate 10 and the retardation layer 20 . The thickness of this adhesive (thickness of the adhesive layer arrange|positioned between the retardation layer 20 and the protective film 30) is 10 micrometers - 40 micrometers, for example.

For example, the laminate obtained by laminating the polarizing plate 10 and the retardation layer 20 is subjected to humidity control treatment (typically is provided to humidification treatment), depending on the configuration of the laminate, it takes a great amount of time until the polarizer absorbs moisture, the polarizer does not absorb moisture sufficiently, and there may be problems such as large unevenness of the moisture absorption state. As a result, it is difficult to stabilize the state of the curvature of the polarizing plate with retardation layer obtained, and there exists a tendency which leads to manufacturing defect of an image display apparatus. As described above, by performing humidity control treatment on the laminate of the first protective layer, the polarizer, and the second protective layer to produce a polarizing plate that satisfies a predetermined absorbance, the state of warpage can be easily stabilized by a short-time humidity control treatment. have.

B. Image display panel

The polarizing plate with a retardation layer may be applied to an image display panel (eg, an organic EL panel). Therefore, the image display panel which concerns on embodiment of this invention has the said polarizing plate with a retardation layer.

4 is a schematic cross-sectional view showing the outline of an image display panel according to one embodiment of the present invention. In the image display panel 200, the polarizing plate 100 with a retardation layer is arrange|positioned so that the retardation layer 20 may become the image display panel main body 150 side rather than the polarizing plate 10. Specifically, the polarizing plate 100 with a retardation layer is attached to the image display panel main body 150 through an adhesive layer (not shown).

When warpage occurs in the polarizing plate 100 (polarizing plate 10) with a retardation layer, warpage may also occur in the image display panel 200 obtained by laminating it on the image display panel main body 150 . The direction and degree of bending of the polarizing plate 100 (polarizing plate 10) with a retardation layer (the direction of unevenness) and the degree of bending may be reflected in the direction and degree of bending of the image display panel 200 obtained. The warped image display panel may cause manufacturing defects of the image display device. According to the polarizing plate in which the warpage is stabilized, manufacturing defects of the image display device may be reduced.

(Example)

Hereinafter, the present invention will be specifically described by way of Examples, but the present invention is not limited by these Examples. In addition, thickness and water vapor transmission rate are the values measured by the following measuring method. In addition, unless otherwise indicated, "part" and "%" in Examples and Comparative Examples are based on weight.

1. Thickness

The thickness of 10 micrometers or less was measured using the scanning electron microscope (JEOL Ltd. make, product name "JSM-7100F"). The thickness exceeding 10 µm was measured using a digital micrometer (manufactured by ANRITSU CORPORATION, product name “KC-351C”).

2. Water vapor permeability (water vapor permeability)

The water vapor transmission rate was measured by the differential pressure gas chromatography method according to JIS K7129-4 and ISO15106-4 (differential pressure method) using a vapor permeability measuring apparatus (manufactured by GTR TEC Corporation, product name "gas permeability/water vapor transmission rate measuring apparatus"). Specifically, the moisture permeability (unit: g/m 2 ·24h) was measured under conditions of a temperature of 40°C, a humidity of 92%RH on the water vapor supply side, and evacuation of the permeation side.

[Example 1]

(Production of polarizing plate)

A long roll of a 30 µm-thick polyvinyl alcohol (PVA)-based resin film (manufactured by KURARAY CO., LTD, product name “PE3000”) is uniaxially stretched in the longitudinal direction to 5.9 times in the longitudinal direction by a roll stretching machine while simultaneously swelling, After performing dyeing|staining, bridge|crosslinking, and a washing|cleaning process in this order, the water vapor transmission rate of 350 g/m<2>*24h and the 12-micrometer-thick polarizer were produced by performing a drying process last.

The said swelling process extended|stretched 2.2 times, processing with 20 degreeC pure water. Subsequently, the dyeing process was extended|stretched 1.4 times, processing in the 30 degreeC aqueous solution whose weight ratio of the iodine and potassium iodide whose iodine density|concentration was adjusted so that the single transmittance of the polarizer obtained might be set to 45.0% in 1:7. Next, the crosslinking treatment adopted two steps of crosslinking treatment, and the crosslinking treatment of the first step was stretched 1.2 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 40°C. The boric acid content of the aqueous solution of the crosslinking process of the 1st stage was 5.0 weight%, and potassium iodide content was 3.0 weight%. In the crosslinking treatment of the second step, it was stretched 1.6 times while processing in an aqueous solution in which boric acid and potassium iodide were dissolved at 65°C. The boric acid content of the aqueous solution of the crosslinking process of the 2nd stage was 4.3 weight%, and potassium iodide content was 5.0 weight%. Then, the washing process was processed with the potassium iodide aqueous solution at 20 degreeC. Potassium iodide content of the aqueous solution of a washing process was 2.6 weight%. Finally, the drying process was carried out at 70 degreeC for 5 minutes, and the polarizer was obtained.

On one side of the polarizer, an HC-COP film (water vapor transmission rate of 1.6 g/m 2 ·24 h, thickness of 29 µm) was bonded as a first protective layer via a polyvinyl alcohol-based adhesive. In addition, the HC-COP film is a film in which the hard coat (HC) layer (3 micrometers in thickness) was formed in the cycloolefin resin (COP) film (26 micrometers in thickness), and it bonded together so that the COP film might become the polarizer side. Next, a TAC film (water vapor transmission rate of 810 g/m 2 ·24 h, thickness of 20 µm) having a Re (550) of 0 nm was bonded to another side of the polarizer as a second protective layer. In this way, a laminate having a structure of HC-COP film (first protective layer)/polarizer/TAC film (second protective layer) was obtained.

The obtained laminate was subjected to a humidity control treatment. The humidity control treatment was performed by placing the laminate in an environment of 35°C and 80%RH (amount of water vapor of 32 g/m 3 ) for 2 minutes while roll conveying the laminate. In this way, a polarizing plate was obtained.

(keep)

A surface protection film (water vapor permeability 15 g/m 2 ·24 h, thickness 38 µm) is bonded to the TAC film side of the obtained polarizing plate, and the polarizing plate is stored in this state at 23° C. and 55% RH (water vapor content of 11 g/m 3) for 30 days. did. The surface protection film is a film in which an adhesive layer (10 µm in thickness) is formed on a PET-based film (28 µm in thickness).

(Production of retardation layer)

42 parts by weight of a polymerizable liquid crystal compound (L-1), 42 parts by weight of a polymerizable liquid crystal compound (L-2), 16 parts by weight of a polymerizable liquid crystal compound (L-3), 0.5 parts by weight of a polymerization initiator (PI-1); 0.09 parts by weight of polymer (T-1), 0.04 parts by weight of polymer (T-2), and 235 parts by weight of cyclopentanone were mixed to obtain a composition. The obtained composition is applied on the TAC film (substrate) on which the alignment film is formed to form a coating film, and the formed coating film is heated to 180 ° C., then cooled to 120 ° C., under a nitrogen atmosphere using a high-pressure mercury lamp at a wavelength of 365 nm. The coating film was irradiated with the ultraviolet-ray of 100 mJ/cm<2>, and the liquid-crystal orientation solidified layer A (2.3 micrometers in thickness) was formed on the base material. The in-plane retardation Re(550) of the obtained liquid-crystal orientation solidified layer A was 140 nm, and Re(450)/Re(550) was 0.87.

Polymerizable liquid crystal compound (L-1)

Polymerizable liquid crystal compound (L-2)

Polymerizable liquid crystal compound (L-3)

Polymerization Initiator (PI-1)

Polymer (T-1)

Polymer (T-2)

20 parts by weight of a side-chain liquid crystal polymer represented by the following formula (1) (numbers 65 and 35 in the formula represent mol% of monomer units and are conveniently represented as block polymers: weight average molecular weight 5000), a nematic liquid crystal phase 80 parts by weight of a polymerizable liquid crystal (manufactured by BASF Japan Ltd.: trade name: PaliocolorLC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Inc.: trade name IRGACURE 907) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating liquid. . And after apply|coating the said coating liquid to the PET base material which performed vertical alignment treatment with a bar coater, the liquid crystal was orientated by heat-drying at 80 degreeC for 4 minutes. By irradiating an ultraviolet-ray to this liquid-crystal layer and hardening the liquid-crystal layer, the liquid-crystal orientation solidified layer B (3 micrometers in thickness) which shows the refractive index characteristic of nz>nx=ny was formed on the base material.

(Production of polarizing plate with retardation layer)

The liquid-crystal orientation-solidified layer A and the liquid-crystal orientation-solidified layer B obtained on the TAC film side of the polarizing plate before the said storage were transcribe|transferred in this order. At this time, it transferred (bonding) so that the angle which the absorption axis of a polarizer and the slow axis of the liquid-crystal orientation solidification layer A make might be set to 45 degrees. Transfer of the liquid-crystal orientation solidification layer A to a polarizing plate was performed through the adhesive layer (acrylic type, thickness 5 micrometers). Next, transfer of the liquid-crystal orientation-solidified layer B to the liquid-crystal orientation-solidified layer A was performed through the ultraviolet curing adhesive agent (thickness 1 micrometer). In addition, transfer (bonding) was performed, roll conveying. In this way, a polarizing plate with a retardation layer was obtained.

(keep)

A separator (PET film, thickness 38 µm) was bonded to the retardation layer side of the obtained polarizing plate with retardation layer through an adhesive layer (acrylic system, thickness 26 µm), and in this state, the polarizing plate with retardation layer was applied at 23 ° C. and 55% RH (amount of water vapor) 11 g/m 3) and stored for 30 days.

[Example 2]

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 humidity control treatment of the laminate was carried out by placing it under an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 4 minutes.

[Example 3]

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 humidity control treatment of the laminate was placed in an environment of 35°C and 80%RH (32 g/m 3 of water vapor) for 7 minutes.

[Example 4]

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 humidity control treatment of the laminate was carried out by placing it in an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 10 minutes.

[Example 5]

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 humidity control treatment of the laminate was carried out by placing it under an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 14 minutes.

[Example 6]

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 humidity control treatment of the laminate was carried out by placing it under an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 17 minutes.

[Comparative Example 1]

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 humidity control treatment of the laminate was carried out by placing it in an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 34 minutes.

[Comparative Example 2]

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 humidity control treatment of the laminate was carried out by placing it under an environment of 35° C. and 80% RH (32 g/m 3 of water vapor) for 1 minute.

The following evaluation was performed about an Example and a comparative example. Table 1 summarizes the evaluation results.

<Evaluation>

1. Absorbance

In Examples and Comparative Examples, the absorbance of the laminate, the polarizing plate before and after storage, and a polarizing plate with a retardation layer (for a polarizing plate with a retardation layer, a polarizing plate obtained by excluding the laminated portion from the pressure-sensitive adhesive layer to the separator having a thickness of 5 μm) was measured by diffuse reflection type. It measured using the infrared moisture content meter (the KURABO INDUSTRIES LTD. make, product name "RM-300"), and evaluated the moisture content. Specifically, in an environment of 23° C. and 55% RH, members other than the lamination part of the HC-COP film/polarizer/TAC film (surface protection film, pressure-sensitive adhesive layer, retardation layer, separator, etc.) were peeled off to prepare a measurement sample. , the measurement sample was measured by setting the absorption axis of the polarizer to be parallel to the infrared light path.

2. Amount of change in warpage

In the Example and the comparative example, the amount of change of the curvature before and behind storage of a polarizing plate and a polarizing plate with a retardation layer was measured. Specifically, a 160 mm x 80 mm size test piece was cut out from the polarizing plate before and after storage (for the polarizing plate with a retardation layer, the polarizing plate obtained by excluding the laminated part from the 5 micrometers-thick adhesive layer to a separator). At this time, it cut out so that the direction of 45 degrees with respect to the absorption axis direction of a polarizer might become a long side direction. The height of the highest part from the plane when the test piece cut out on the plane was left still so that the TAC film side might become the plane side was measured, the amount of curvature was measured, and the amount of change of the curvature before and behind storage was calculated|required. Here, the case where the bending was convex to the stationary surface side was "positive (+)", and the case where the bending was convex to the opposite side to the stationary surface was defined as "negative (-)".

In an Example, the change amount of the absorbance before and behind storage is small, and it turns out that the state of the curvature of a polarizing plate is stable.

[Reference example]

The liquid-crystal orientation-solidified layer A obtained by carrying out similarly to Example 1 was transcribe|transferred to the laminated body obtained by carrying out similarly to Example 1, Then, the liquid-crystal orientation-solidified layer B obtained by carrying out similarly to Example 1 was laminated|stacked, and in this state (liquid-crystal orientation solidification) The PET substrate of layer B was subjected to humidity control treatment by placing it under an environment of 35° C. and 80% RH (with a water vapor content of 32 g/m 3 ) (without peeling) for 10 minutes, but the absorbance was not changed by the humidity control treatment as in the above example. Furthermore, the liquid-crystal alignment-solidified layer A obtained by carrying out similarly to Example 1 was transcribe|transferred to the laminated body obtained by carrying out similarly to Example 1, and the liquid-crystal orientation solidified layer B obtained by carrying out similarly to Example 1 except having used TAC base material then as a base material It was laminated and placed in this state (without peeling of the TAC substrate of the liquid crystal orientation solidified layer B) under an environment of 35° C. and 80% RH (water vapor content of 32 g/m 3 ) for 10 minutes to control the humidity, but absorbance immediately after the humidity control treatment did not change before the humidity control treatment, and when 5 days had elapsed from the humidity control treatment (storage for 5 days), the absorbance started to rise, and the curvature also changed. It took time until the state of warpage was stabilized in this way.

The polarizing plate according to the embodiment of the present invention is used as a polarizing plate of an image display device, and can also be used in an image display device capable of being curved or bent, folded, or wound. Representative examples of the image display device include a liquid crystal display device, an organic EL display device, and an inorganic EL display device.

10: polarizer
11: Polarizer
12: first protective layer
13: second protective layer
20: retardation layer
21: first retardation layer
22: second retardation layer
30: protective film
100: polarizing plate with retardation layer

Claims (8)

a first protective layer having a moisture permeability of 40 g/m 2 ·24 h or less at 40° C. and 92% RH;
polarizer and
A second protective layer having a water vapor transmission rate of 350 g/m 2 ·24 h or more at 40° C. and 92% RH in this order,
A polarizing plate having an absorbance of 0.0100 or more and 0.0155 or less as measured by an infrared moisture meter. The method of claim 1,
The first protective layer is a polarizing plate comprising a cycloolefin-based resin. The method of claim 1,
The second protective layer is a polarizing plate comprising a cellulose-based resin. A polarizing plate according to any one of claims 1 to 3;
A polarizing plate with a retardation layer having a retardation layer disposed on the second protective layer side of the polarizing plate. 5. The method of claim 4,
The retardation layer is a polarizing plate with a retardation layer which is an alignment-solidified layer of a liquid crystal compound. A first protective layer having a water vapor transmission rate of 40 g/m 2 ·24h or less at 40°C and 92%RH, a polarizer and a second protective layer having a water vapor transmission rate of 350 g/m2·24h or more at 40°C and 92%RH in this order preparing a laminate having as
and subjecting the laminate to a humidity control treatment;
The manufacturing method of the polarizing plate which obtains the polarizing plate whose absorbance by infrared moisture meter measurement is 0.0100 or more and 0.0155 or less. 7. The method of claim 6,
The manufacturing method of performing the said humidity control process in the state in which the main surface of one side of the said 2nd protective layer is exposed. The manufacturing method of the polarizing plate with retardation layer comprising laminating|stacking a retardation layer on the said 2nd protective layer side of the polarizing plate obtained by the manufacturing method of Claim 6 or 7.

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