KR20220076468A - Polarizing plate with retardation layer and organic electroluminescent display device using same - Google Patents

Abstract

A polarizing plate with a retardation layer in which discoloration is significantly suppressed when applied to an organic EL display device is provided. The polarizing plate with a retardation layer of this invention contains the polarizing plate which contains a protective layer at least on the visual recognition side of a polarizer and a polarizer, and the retardation layer arrange|positioned on the opposite side to the visual recognition side of a polarizing plate. The water vapor transmission rate of the protective layer on the visual side is 200 g/m 2 ·24 h or more, and is larger than the water vapor transmission rate of the retardation layer.

Description

Polarizing plate with retardation layer and organic electroluminescent display device using same

The present invention relates to a polarizing plate with a retardation layer and an organic electroluminescent (EL) display device using the same.

In recent years, with the spread of a thin display, the display (organic electroluminescent display apparatus) in which the organic electroluminescent panel was mounted is proposed. Since an organic EL panel has a highly reflective metal layer, it is easy to produce problems, such as external light reflection and background reflection. Accordingly, it is known to prevent these problems by providing a circularly polarizing plate on the viewer side (for example, Patent Documents 1 to 3). However, there is a problem that the circularly polarizing plate provided in the organic EL display device is easily discolored.

Japanese Laid-Open Patent Publication No. 2003-311239 Japanese Laid-Open Patent Publication No. 2002-372622 Japanese Patent Publication No. 3325560

The present invention has been made in order to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer in which discoloration is remarkably suppressed when applied to an organic EL display device.

The polarizing plate with a retardation layer of this invention contains the polarizing plate which contains a protective layer at least on the visual recognition side of a polarizer and this polarizer, and the retardation layer arrange|positioned on the opposite side to the visual recognition side of this polarizing plate. The water vapor transmission rate of the protective layer on the visual side is 200 g/m 2 ·24 h or more, and is larger than the water vapor transmission rate of the retardation layer.

In one embodiment, the polarizing plate includes a protective layer only on the viewer side.

In one embodiment, the difference of the water vapor transmission rate of the said visual recognition side protective layer and the said retardation layer is 200 g/m<2>*24h or more.

In one embodiment, the polarizing plate further includes another protective layer on the opposite side to the viewer side of the polarizer, and the water vapor transmission rate of the protective layer on the viewer side is the smaller of the water vapor transmission rate of the other protective layer and the water vapor transmission rate of the retardation layer greater than the moisture permeability of In one embodiment, the phase difference layer is an alignment-solidified layer of a liquid crystal compound, and the water vapor transmission rate of the visual recognition side protective layer is larger than that of the other protective layer. In one embodiment, the difference between the water vapor transmission rate of the visual recognition side protective layer, the water vapor transmission rate of the other protective layer, and the water vapor transmission rate of the phase difference layer, which is smaller, is 200 g/m 2 ·24 h or more.

In one embodiment, the moisture permeability of the said other protective layer is 150 g/m<2>*24h or less.

In one embodiment, the thickness of the said polarizer is 8 micrometers or less.

In one embodiment, the total thickness of the said polarizing plate with a retardation layer is 20 micrometers or more and 100 micrometers or less.

According to another aspect of the present invention, an organic electroluminescent display device is provided. This organic electroluminescent display device is equipped with said polarizing plate with a retardation layer.

According to the embodiment of the present invention, in the polarizing plate with a retardation layer, the water vapor transmission rate of the visual recognition side protective layer is made larger than the water vapor transmission rate of the smaller one of the moisture vapor transmission rate of the protective layer (if present) on the side opposite to the visual recognition side and the retardation layer. , a polarizing plate with a retardation layer in which discoloration was remarkably suppressed when applied to an organic EL display device can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this 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, the slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and 'nz' is the refractive index It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. For example, 'Re(550)' is an in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) can be 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 phase difference in the thickness direction measured with light having a wavelength of λnm at 23°C. For example, 'Rth (550)' is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) can be 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 can be calculated|required by Nz=Rth/Re.

(5) angle

When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, '45°' means ±45°.

A. Overall configuration of polarizing plate with retardation layer

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this invention. The polarizing plate 100 with a retardation layer of the example of illustration typically has the polarizing plate 10 and the retardation layer 20 in this order from the visual recognition side. The polarizing plate 10 includes a polarizer 11 and a protective layer (viewing side protective layer) 12 at least on the viewer side of the polarizer 11 . In the illustrated example, the protective layer (inner protective layer) 13 is provided on the side opposite to the viewing side of the polarizer 11, but the protective layer 13 may be omitted depending on the purpose or the like. For example, when the retardation layer 20 is composed of a stretched film of a resin film and can also serve as a protective layer of the polarizer, the protective layer 13 may be omitted. On the other hand, when the retardation layer 20 is an alignment-solidified layer of a liquid crystal compound, the protective layer 13 is typically provided. Practically, an adhesive layer (not shown) is provided on the opposite side to the polarizing plate 10 of the retardation layer 20 (that is, as the outermost layer on the opposite side to the viewing side), and the polarizing plate with a retardation layer is applied to the organic EL cell. It is possible to attach (貼付). Moreover, it is preferable that the peeling film is temporarily attached to the surface of an adhesive layer until the polarizing plate with retardation layer is provided for use. By temporarily adhering a peeling film, while protecting an adhesive layer, roll formation of a polarizing plate with retardation layer is attained.

In the embodiment of the present invention, the water vapor transmission rate of the protective layer 12 is larger than the water vapor transmission rate of the smaller one of the water vapor transmission rate of the protective layer 13 (if present) and the water vapor transmission rate of the retardation layer 20 . Specifically, it is as follows: (1) when the protective layer 13 is omitted, the water vapor transmission rate of the protective layer 12 is greater than that of the retardation layer 20; (2) when the protective layer 13 is present, the water vapor transmission rate of the protective layer 12 is greater than the water vapor transmission rate of the smaller one of the water vapor transmission rate of the protective layer 13 and the retardation layer 20; (3) When the protective layer 13 is present and the retardation layer 20 is an alignment-solidified layer of a liquid crystal compound, the moisture permeability of the protective layer 12 is greater than that of the protective layer 13 . The present inventors face a new problem that the polarizing plate with a retardation layer is discolored when a polarizing plate with a retardation layer is applied to an organic EL display device. (substantially, ammonium ion). In addition, as a result of earnestly examining the means for suppressing discoloration by ammonia, it is possible to significantly suppress the discoloration by blocking as much as possible ammonium ions penetrating into the polarizer and discharging the penetrating ammonium ions as much as possible. found Based on such knowledge, by reducing the water vapor transmission rate of the protective layer or retardation layer on the side opposite to the viewing side (organic EL panel side), ammonium ions penetrating into the polarizer are blocked as much as possible, and the viewing side (the side farther from the organic EL panel) ), by increasing the water vapor transmission rate, it was realized to discharge the ammonium ions that penetrated as much as possible, and the new subject was solved. In addition, the protective layer of the polarizer is designed to reduce the moisture permeability of the protective layer on the outside (visible side) due to its main purpose of protecting the polarizer from moisture (water vapor). It is based on a technical idea that is completely opposite to the technical common sense of the industry.

The difference between the water vapor transmission rate of the protective layer 12 and the water vapor transmission rate of the smaller one of the water vapor transmission rate of the protective layer 13 (if present) and the retardation layer 20 is preferably 200 g/m 2 ·24 h or more, more preferably Preferably, it is 220 g/m 2 ·24 h or more, more preferably 250 g/m 2 ·24 h or more, and particularly preferably 300 g/m 2 ·24 h or more. The upper limit of the tea may be, for example, 600 g/m 2 ·24h. The discoloration of a polarizing plate with a retardation layer can be suppressed more favorably as the said difference is such a range.

The moisture permeability of the protective layer 12 is 200 g/m 2 ·24 h or more, preferably 300 g/m 2 · 24 h or more, more preferably 330 g/m 2 · 24 h or more, and still more preferably 360 g/m 2 · 24 h or more. , particularly preferably 400 g/m 2 ·24 h or more. The upper limit of the moisture permeability of the protective layer 12 may be, for example, 650 g/m 2 ·24h. The moisture permeability of the protective layer 13 is preferably 150 g/m 2 ·24 h or less, more preferably 100 g/m 2 · 24 h or less, still more preferably 70 g/m 2 ·24 h or less, and particularly preferably 50 g/m 2 ·24 h or less. It is less than m2·24h. The lower the moisture permeability of the protective layer 13, the more preferable, and the lower limit thereof may be, for example, 5 g/m 2 ·24h. When the protective layer 13 is not present, or when the water vapor transmission rate of the retardation layer 20 is smaller than that of the protective layer 13, the water vapor transmission rate of the retardation layer 20 is preferably 150 g/m 2 ·24h or less. , more preferably 100 g/m 2 ·24 h or less, still more preferably 70 g/m 2 ·24 h or less, and particularly preferably 50 g/m 2 ·24 h or less. The lower the moisture permeability of the retardation layer 20, the more preferable, and the lower limit thereof may be, for example, 5 g/m 2 ·24h. If the moisture permeability of the protective layers 12 and 13 and the retardation layer 20 is within such a range, it is easy to make the difference between the moisture permeability into a desired range. In addition, the water vapor transmission rate can be measured according to JIS Z 0208.

The total thickness of the polarizing plate with a retardation layer becomes like this. Preferably it is 120 micrometers or less, More preferably, it is 100 micrometers or less, More preferably, it is 80 micrometers or less. The lower limit of the total thickness is preferably 20 µm, more preferably 45 µm. A polarizing plate with a retardation layer having such a total thickness may have extremely excellent flexibility and bending durability. As a result, the polarizing plate with a retardation layer can be applied especially suitably to a curved organic electroluminescent display device and/or a bendable or bendable organic electroluminescent display device.

The polarizing plate with a retardation layer may further contain the other optical function layer. The type, characteristic, number, combination, arrangement position, and the like of the optical function layers that can be provided in the polarizing plate with a retardation layer may be appropriately set according to the purpose. For example, the polarizing plate with a retardation layer may further contain the isotropic base material with a conductive layer or a conductive layer (neither is shown). A conductive layer or an isotropic substrate with a conductive layer is typically provided on the outside of the retardation layer 20 (on the opposite side to the polarizing plate 10 ). When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between the organic EL cell and the polarizing plate. Moreover, for example, the polarizing plate with a retardation layer may further contain the other retardation layer. Other optical properties (eg, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the retardation layer may be appropriately set according to the purpose.

A single-leaf shape may be sufficient as a polarizing plate with retardation layer, and the shape of a long picture may be sufficient as it. As used herein, 'long shape' means an elongate shape having a sufficiently long length with respect to the width, and includes, for example, an elongated shape with a length of 10 times or more, preferably 20 times or more with respect to the width. The elongate polarizing plate with retardation layer can be wound in roll shape.

Hereinafter, the components of a polarizing plate with a retardation layer are demonstrated in detail.

B.　Polarizer

B-1. polarizer

As the polarizer 11, any suitable polarizer may be employed. For example, a single-layered resin film may be sufficient as the resin film which forms a polarizer, and the laminated body of two or more layers may be sufficient as it.

As a specific example of a polarizer constituted from a single-layer resin film, a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, an ethylene/vinyl acetate copolymer-based partially saponified film, etc. polyene-based oriented films such as those subjected to the dyeing treatment and stretching treatment with a dichroic substance of PVA and dehydrochloric acid treatment products of PVA and polyvinyl chloride. Preferably, from the viewpoint of excellent optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used.

The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. Preferably the draw ratio of the said uniaxial stretching is 3-7 times. Extending|stretching may be performed after a dyeing process, and may be performed, dyeing|staining. Moreover, you may dye|stain after extending|stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, and the like. For example, by immersing the PVA-based film in water and washing with water before dyeing, it is possible to not only wash the surface of the PVA-based film from contamination and anti-blocking agent, but also to swell the PVA-based film to prevent staining of dyeing.

As a specific example of the polarizer obtained using a laminated body, a laminated body of a resin base material and the PVA-type resin layer (PVA-type resin film) laminated|stacked on the said resin base material, or a resin base material and the PVA-type resin layer coated and formed on the said resin base material. The light polarizer obtained using the laminated body of this is mentioned. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer applied and formed on the resin substrate is, for example, a PVA-based resin solution applied to a resin substrate, dried to form a PVA-based resin layer on the resin substrate, obtaining a laminate of a resin substrate and a PVA-based resin layer; It can be produced by; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, extending|stretching includes extending|stretching by immersing a laminated body in boric-acid aqueous solution typically. In addition, the stretching may further include air stretching the laminate at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer of the polarizer), or the resin substrate is peeled from the resin substrate/polarizer laminate, Any suitable protective layer may be laminated and used. The detail of the manufacturing method of such a polarizer is described in Unexamined-Japanese-Patent No. 2012-73580, and Unexamined-Japanese-Patent No. 6470455, for example. These publications are incorporated herein by reference in their entirety.

The thickness of a polarizer becomes like this. Preferably it is 15 micrometers or less, More preferably, it is 12 micrometers or less, More preferably, it is 10 micrometers or less, Especially preferably, it is 8 micrometers or less. On the other hand, the thickness of the polarizer is preferably 1 µm or more, more preferably 2 µm or more, and still more preferably 3 µm or more. If the thickness of a polarizer is such a range, the curl at the time of a heating can be suppressed favorably, and the external appearance durability at the time of a favorable heating can be acquired.

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 43.0% to 46.0%, and 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.

B-2. protective layer

The visual recognition side protective layer 12 and the inner protective layer 13 (if present) are each composed of any suitable film that can be used as a protective layer of the polarizer, as long as they each have the moisture permeability as described above. Examples of the material constituting the inner protective layer 13 include cycloolefin-based resins such as polynorbornene, (meth)acrylic-based resins, polyethylene terephthalate (PET), and polyester-based resins such as polyethylene naphthalate (PEN). , polyolefin-based resins such as polyethylene, and polycarbonate-based resins. As a representative example of (meth)acrylic-type resin, the (meth)acrylic-type resin which has a lactone ring structure is mentioned. The (meth)acrylic resin having a lactone ring structure is, for example, Japanese Patent Application Laid-Open No. 2000-230016, Japanese Patent Application Laid-Open No. 2001-151814, Japanese Patent Application Laid-Open No. 2002-120326, and Japanese Patent Application Laid-Open No. 2002 -254544 and Japanese Unexamined Patent Publication No. 2005-146084. These publications are incorporated herein by reference. The inner protective layer 13 is preferably made of a cycloolefin-based resin. Examples of the material constituting the visual recognition-side protective layer 12 include cellulose-based resins such as triacetyl cellulose (TAC), and resins capable of forming microporous films (eg, polyurethane-based resins).

The polarizing plate with a retardation layer is typically arrange|positioned on the visual recognition side of an organic electroluminescent display device so that it may mention later, and the protective layer 12 is arrange|positioned at the visual recognition side. Accordingly, the protective layer 12 may be subjected to a surface treatment such as a hard coat treatment, an antireflection treatment, an antistick treatment, and an antiglare treatment, if necessary. In addition/or, the protective layer 12 is subjected, if necessary, to a process for improving visibility when visually recognized through polarized sunglasses (typically, imparting a (other) circular polarization function, imparting an ultra-high phase difference). it may be By performing such a process, excellent visibility can be implement|achieved even when a display screen is visually recognized through polarization lenses, such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can be suitably applied also to the organic electroluminescent display which can be used outdoors.

The thickness of the protective layer 12 may be appropriately set according to a desired moisture permeability. The thickness of the protective layer 12 is preferably 10 µm to 80 µm, more preferably 15 µm to 70 µm, still more preferably 20 µm to 50 µm. In addition, when surface treatment is performed, the thickness of the protective layer 12 is the thickness including the thickness of a surface treatment layer.

In one embodiment, the protective layer 13 is preferably optically isotropic. In the present 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 13 can also be appropriately set according to the desired moisture permeability. The thickness of the protective layer 13 is preferably 10 µm to 80 µm, more preferably 20 µm to 70 µm, still more preferably 30 µm to 50 µm. When the retardation layer 20 is a stretched film of a resin film, the protective layer 13 may be preferably omitted from the viewpoint of reducing the thickness.

C. retardation layer

A single layer may be sufficient as the retardation layer 20, and it may have a laminated structure (substantially two-layer structure).

When the retardation layer 20 is a single layer, the retardation layer 20 may typically function as a λ/4 plate. The retardation layer is typically provided to impart antireflection properties to the organic EL display device. The retardation layer typically exhibits a relationship of refractive index characteristics of nx>ny=nz. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 120 nm to 160 nm. In addition, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where 'ny=nz' is substantially the same. Therefore, within the range which does not impair the effect of this invention, it may become ny>nz or ny<nz.

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

When the retardation layer is a single layer, the retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. In this case, Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be realized.

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 about 45°. If the angle is within such a range, an organic EL display device having very excellent antireflection properties can be obtained by forming the retardation layer as a ?/4 plate as described above.

The retardation layer may be made of any suitable material as long as the above characteristics can be satisfied. Specifically, a stretched film of a resin film may be sufficient as retardation layer, and the alignment-solidified layer (henceforth liquid crystal alignment-solidified layer) of a liquid crystal compound may be sufficient as it.

When the retardation layer is a stretched film of a resin film, as a typical example of the resin constituting the resin film, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, simply referred to as a polycarbonate-based resin in some cases) is mentioned. As polycarbonate-type resin, any suitable polycarbonate-type resin can be used as long as a desired water vapor transmission rate is obtained. For example, the polycarbonate resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri or polyethylene glycol. , and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alkylene glycol or spiro glycol. Preferably, the polycarbonate resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from alicyclic dimethanol, and/or di , containing a structural unit derived from tri or polyethylene glycol; More preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri or polyethylene glycol. Polycarbonate resin may contain the structural unit derived from another dihydroxy compound as needed. The retardation layer may be formed by stretching the film composed of the polycarbonate-based resin as described above under any suitable stretching conditions. In addition, the detail of the formation method of polycarbonate-type resin and retardation layer is, for example, Unexamined-Japanese-Patent No. 2014-10291, Unexamined-Japanese-Patent No. 2014-26266, Unexamined-Japanese-Patent No. 2015-212816, Unexamined-Japanese-Patent No. It is described in Patent Publication No. 2015-212817, Japanese Patent Application Laid-Open No. 2015-212818, Japanese Patent Application Laid-Open No. 2017-54093, and Japanese Patent Application Laid-Open No. 2018-60014. The descriptions of these publications are incorporated herein by reference.

When the retardation layer is a liquid crystal alignment solidification layer, by using a liquid crystal compound, the difference between nx and ny of the retardation layer obtained can be significantly increased compared to that of a non-liquid crystal material, so the thickness of the retardation layer for obtaining a desired in-plane retardation is can be made significantly smaller. As a result, further thinning of the polarizing plate with a retardation layer (as a result, organic electroluminescent display apparatus) can be implement|achieved. As used herein, the term 'alignment solidified layer' refers to a layer in which the liquid crystal compound is oriented in a predetermined direction in the layer, and the alignment state thereof is fixed. In addition, the 'alignment hardening layer' is a concept including an alignment hardening layer obtained by curing a liquid crystal monomer. In this embodiment, the rod-shaped liquid crystal compounds are typically oriented in a state aligned in the slow axis direction of the retardation layer (homogeneous alignment). The specific example of a liquid crystal compound and the detail of the formation method of a liquid-crystal orientation solidification layer are described in Unexamined-Japanese-Patent No. 2006-163343 and Unexamined-Japanese-Patent No. 2006-178389, for example. The descriptions of these publications are incorporated herein by reference.

The thickness of the retardation layer may be typically set to a thickness that can properly function as a λ/4 plate. When the retardation layer is a stretched film of a resin film, the thickness of the retardation layer may be, for example, 10 μm to 60 μm. When the retardation layer is a liquid crystal alignment solidification layer, the thickness of the retardation layer may be, for example, 1 µm to 5 µm.

When the retardation layer has a laminated structure, the retardation layer typically has a two-layered structure of a first liquid-crystal alignment-solidified layer and a second liquid-crystal alignment-solidified layer. In this case, either one of the first liquid crystal alignment-solidified layer or the second liquid-crystal alignment-solidified layer can function as a λ/2 plate, and the other can function as a λ/4 plate. Here, the case where the first liquid-crystal alignment-solidified layer can function as a λ/2 plate and the second liquid-crystal alignment-solidified layer can function as a λ/4 plate is described, but these may be reversed. The thickness of the first liquid crystal alignment solidification layer may be adjusted so that a desired in-plane retardation of the λ/2 plate is obtained, and may be, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment solidification layer may be adjusted so that a desired in-plane retardation of the λ/4 plate is obtained, and may be, for example, 1.0 μm to 2.5 μm. Preferably in-plane retardation Re(550) of a 1st liquid-crystal orientation solidification layer is 200 nm - 300 nm, More preferably, they are 230 nm - 290 nm, More preferably, they are 250 nm - 280 nm. As mentioned above, in-plane retardation Re(550) of a 2nd liquid-crystal orientation solidified layer becomes like this. Preferably it is 100 nm - 190 nm, More preferably, they are 110 nm - 170 nm, More preferably, they are 120 nm - 160 nm. The angle between the slow axis of the first liquid crystal alignment-solidified layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and still more preferably about 15°. The angle between the slow axis of the second liquid crystal alignment-solidified layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, still more preferably about 75°. With such a configuration, it is possible to obtain a characteristic close to the ideal reverse wavelength dispersion characteristic, and as a result, an extremely excellent antireflection characteristic can be realized.

D. Image display device

The polarizing plate with a retardation layer as described in item A to item C above can be applied to an organic EL display device. Accordingly, an embodiment of the present invention includes an organic EL display device using such a polarizing plate with a retardation layer. The organic electroluminescence display which concerns on embodiment of this invention is equipped with the polarizing plate with a retardation layer as described in the said section A to C section on the visual recognition side. The polarizing plate with a retardation layer is laminated|stacked so that a retardation layer may become the organic EL cell side (a polarizing plate may become a visual recognition side). In one embodiment, the organic EL display device has a curved shape (substantially curved display screen) and/or is bendable or bendable. As described above, the present inventors have discovered a new problem that, when a polarizing plate with a retardation layer is applied to an organic EL display device, the polarizing plate with a retardation layer is discolored by ammonia (substantially ammonium ions) generated from the organic EL panel, The said subject was solved by the said polarizing plate with a retardation layer as described in the said A section to C section. That is, in an organic electroluminescent display device, the effect of the polarizing plate with retardation layer which concerns on embodiment of this invention is remarkable.

[Example]

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic is as follows. In addition, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

(1) thickness

The thickness of 10 µm or less was measured using an interference film thickness measuring instrument (manufactured by Otsuka Electronics, product name 'MCPD-3000'). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name 'KC-351C').

(2) Single transmittance and polarization degree

For the polarizing plates used in Examples and Comparative Examples, single transmittance (Ts), parallel transmittance (Tp), orthogonal transmittance (Tc) measured using an ultraviolet/visible light spectrophotometer ('LPF-2000' manufactured by Otsuka Denshi Co., Ltd.) was taken as Ts, Tp, and Tc of the polarizer, respectively. These Ts, Tp, and Tc are Y values which measured by the 2 degree field of view (C light source) of JIS Z8701, and performed visibility correction|amendment. The degree of polarization P was calculated|required by the following formula from the obtained Tp and Tc.

Polarization degree P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

(3) moisture permeability

It measured according to JIS Z 0208. Specifically, the protective layer or retardation layer (film constituting the film) used in Examples and Comparative Examples was cut out in a circular shape of 10 cm phi to obtain a measurement sample. About this measurement sample, the water vapor transmission rate was measured under the test conditions of 40 degreeC 92%RH using "MOCON" manufactured by Hitachi Corporation.

(4) Ammonia decolorization test

10 g of a 10% aqueous ammonia solution was placed in a glass bottle (cylindrical shape having a diameter of 30 mm and a depth of 50 mm). At this time, the distance from the liquid level of the aqueous ammonia solution to the inlet (top) of the glass bottle was about 30 mm. The polarizing plate with retardation layer obtained in Examples and Comparative Examples was cut out to a size of 15 mm x 15 mm, and a pressure-sensitive adhesive layer was provided on the retardation layer side as measurement data. The measurement data were attached to the edge of the mouth of the glass bottle through an adhesive layer, so that the mouth of the glass bottle was all covered with this measurement data, and steam was prevented from leaking from the gap. The glass bottle covered with the measurement data was heated at 60° C. for 2 hours. The polarization degree before heating of the polarizing plate with retardation layer (substantially, a polarizer) was P ₀ , and the polarization degree after heating was P ₂₀ , and ΔP was calculated from the following formula. It means that discoloration by ammonia is suppressed, so that ΔP is small.

ΔP=P ₂₀ -P ₀

[Example 1]

1. Fabrication of polarizer

As a thermoplastic resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 µm) having a long water absorption rate of 0.75% and a Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate.

Potassium iodide in polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name 'Goseimer Z410') in a ratio of 9: 1 to 100 parts by weight of a PVA-based resin mixed 13 parts by weight was added and dissolved in water to prepare a PVA aqueous solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm to prepare a laminate.

The obtained laminate was uniaxially stretched at the free end by 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130°C (air-assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, in a dyeing bath with a liquid temperature of 30°C (an aqueous solution of iodine obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water), the single transmittance (Ts) of the finally obtained polarizing film is 43.0% It was immersed for 60 seconds while adjusting the concentration as much as possible (dyeing treatment).

Then, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 parts by weight of water and 5 parts by weight of boric acid) with a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, while the laminate is immersed in an aqueous boric acid solution (boric acid concentration: 4.0 wt%, potassium iodide 5.0 wt%) at a liquid temperature of 70°C, the total draw ratio is 5.5 in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds. Uniaxial stretching was performed so that it might become double (underwater stretching process).

Then, the laminated body was immersed in the washing|cleaning bath (aqueous solution obtained by mix|blending 4 weight part of potassium iodide with respect to 100 weight part of water) with a liquid temperature of 20 degreeC (washing process).

After that, it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at 75°C while drying in an oven maintained at 90°C for about 2 seconds (dry shrinkage treatment). The shrinkage ratio in the width direction of the laminate by the drying shrinkage treatment was 5.2%.

In this way, the polarizer with a thickness of 5 micrometers was formed on the resin base material.

2. 　Manufacture of polarizing plate

The HC-TAC film was pasted together on the polarizer surface of the laminated body of the resin base material/polarizer obtained above via an ultraviolet curing adhesive. Specifically, it coated so that the thickness of a curable adhesive might be set to 1.0 micrometer, and it bonded together using the roll machine. Thereafter, UV rays were irradiated from the HC-TAC film side to cure the adhesive. In addition, the HC-TAC film is a film in which the hard coat (HC) layer (thickness 7 micrometers) was formed in the triacetyl cellulose (TAC) film (25 micrometers), and it bonded together so that the TAC film might become a polarizer side. Next, the resin base material was peeled, and the cycloolefin resin film (thickness: 13 micrometers: hereafter, a COP film) was carried out similarly to the above and bonded together on the said peeling surface. The water vapor transmission rate of the HC-TAC film was 427 g/m 2 ·24 h, and the water vapor transmission rate of the COP film was 35 g/m 2 ·24 h. In this way, the polarizing plate which has the structure of visual recognition side protective layer (HC-TAC film)/polarizer/other protective layer (COP film) was obtained.

3. Preparation of retardation film constituting retardation layer

3-1. Polymerization of polyester carbonate-based resins

Polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 mass Parts (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 ^-2 parts by mass (6.78×10 ^-5 mol) of calcium acetate monohydrate as a catalyst were added. After replacing the inside of the reactor with reduced pressure nitrogen, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100°C. The internal temperature was made to reach 220 degreeC 40 minutes after the start of temperature rise, and while controlling so that this temperature might be maintained, pressure reduction was started, and it was set to 13.3 kPa in 90 minutes after reaching 220 degreeC. The phenol vapor produced by the polymerization reaction was led to a reflux condenser at 100° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was led to the condenser at 45° C. and recovered. After nitrogen was introduced into the first reactor and the pressure was returned to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature increase and pressure reduction in the 2nd reactor were started, and it was set as the internal temperature of 240 degreeC and the pressure of 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor and the pressure was returned, and the resulting polyester carbonate-based resin was extruded in water, and the strands were cut to obtain pellets.

3-2. Production of retardation film

After vacuum drying the obtained polyester carbonate-based resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machinery Co., Ltd., cylinder set temperature: 250 ° C), T-die (width 200 mm, set temperature: 250 ° C), A 135-micrometer-thick long resin film was produced using the film film forming apparatus provided with the chilled roll (set temperature: 120-130 degreeC) and the winder. The obtained elongate resin film was extended|stretched by the extending|stretching temperature of 133 degreeC, and a draw ratio of 2.8 times in the width direction, and the 47-micrometer-thick retardation film was obtained. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.82, and Nz coefficient was 1.12. Moreover, the water vapor transmission rate of the obtained retardation film was 75 g/m<2>*24h.

4. Preparation of polarizing plate with retardation layer

On the surface of the other protective layer (COP film) of the polarizing plate obtained in 2. above, the retardation film obtained in 3. above was bonded through an acrylic pressure-sensitive adhesive (thickness: 5 µm). At this time, it bonded together so that the absorption axis of a polarizer and the slow axis of retardation film might make the angle of 45 degrees. In this way, the polarizing plate with retardation layer which has the structure of visual recognition side protective layer (HC-TAC film)/polarizer/other protective layer (COP film)/adhesive layer/retardation layer was obtained. The total thickness of the obtained polarizing plate with retardation layer was 112 micrometers. Moreover, the obtained polarizing plate with retardation layer was used for evaluation of said (4). A result is shown in Table 1.

[Example 2]

1. Fabrication of polarizing plate

It carried out similarly to Example 1, and produced the polarizing plate.

2. Preparation of liquid crystal alignment solidification layer constituting retardation layer

55 parts of the compound represented by the formula (I), 25 parts of the compound represented by the formula (II), and 20 parts of the compound represented by the formula (III) are added to 400 parts of cyclopentanone (CPN), followed by heating to 60° C. and stirring to dissolve After confirming dissolution, return to room temperature and add 3 parts of Igacure 907 (manufactured by BASF Japan), 0.2 parts of Megapack F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) , further stirred to obtain a solution. The solution was clear and homogeneous. The resulting solution was filtered through a 0.20 µm membrane filter to obtain a polymerizable composition. On the other hand, a coating film was obtained by apply|coating the polyimide solution for alignment films to a 0.7 mm-thick glass substrate using the spin coating method, drying at 100 degreeC for 10 minutes, and baking at 200 degreeC for 60 minutes. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing apparatus. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating, and dried at 100°C for 2 minutes. After cooling the obtained coating film to room temperature, the ultraviolet-ray was irradiated for 30 second at the intensity|strength of 30 mW/cm<2> using a high pressure mercury lamp, and the liquid-crystal orientation solidification layer was obtained. The in-plane retardation Re(550) of the liquid crystal alignment solidified layer was 130 nm. In addition, Re(450)/Re(550) of the liquid crystal alignment solidified layer was 0.851, indicating reverse dispersion wavelength characteristics.

3. Preparation of polarizing plate with retardation layer

On the surface of the other protective layer (COP film) of the polarizing plate obtained in 1. above, the liquid-crystal alignment solidified layer obtained in 2. above was transcribed. At this time, transcription|transfer (bonding) was performed so that the angle which the absorption axis of a polarizer and the slow axis of a liquid-crystal orientation solidification layer make might be 45 degrees. In addition, transcription|transfer (bonding) was performed through the ultraviolet curable adhesive (1.0 micrometer in thickness). In this way, a polarizing plate with a retardation layer having the structure of a visual recognition side protective layer (HC-TAC film)/polarizer/other protective layer (COP film)/adhesive layer/retardation layer (liquid crystal orientation solidified layer) was obtained. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

[Example 3]

Except not having provided another protective layer, it carried out similarly to Example 1, and obtained the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

[Examples 4 to 6]

A polarizing plate with a retardation layer was obtained by making the visual recognition side protective layer, a polarizer, another protective layer, and retardation layer into the structure shown in Table 1. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

[Comparative Example 1]

It carried out similarly to Example 1, and produced the laminated body of the resin base material/polarizer. The HC-COP film was pasted together on the polarizer surface of the laminated body of the obtained resin base material / polarizer in the same manner as in Example 1. The HC-COP film was the film in which the hard-coat (HC) layer (2 micrometers in thickness) was formed in the COP film (25 micrometers in thickness), and it bonded together so that a COP film might become the polarizer side. Next, the resin base material was peeled, and the COP film similar to Example 1 was carried out similarly to Example 1, and was bonded together on the said peeling surface. The water vapor transmission rate of the HC-COP film was 17 g/m 2 ·24 h, and the water vapor transmission rate of the COP film was 35 g/m 2 ·24 h. In this way, the polarizing plate which has the structure of visual recognition side protective layer (HC-COP film)/polarizer/other protective layer (COP film) was obtained. The following procedure was carried out similarly to Example 1, and obtained the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

[Comparative Examples 2 to 10]

A polarizing plate with a retardation layer was obtained by making the visual recognition side protective layer, a polarizer, another protective layer, and retardation layer into the structure shown in Table 1. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

[Table 1]

[evaluation]

As is clear from Table 1, according to the embodiment of the present invention, it is possible to obtain a polarizing plate with a retardation layer in which the degree of polarization hardly changes (that is, does not discolor) even when exposed to ammonia. That is, according to the embodiment of the present invention, it can be seen that when applied to an organic EL display device, a polarizing plate with a retardation layer in which discoloration is suppressed can be realized. On the other hand, in the polarizing plate with a retardation layer of a comparative example, the polarization function is greatly reduced, and the polarization function is substantially lost in the majority of the.

[Industrial Applicability]

The polarizing plate with a retardation layer of this invention is used suitably as a circularly polarizing plate for reflection prevention of organic electroluminescent display apparatus.

10: polarizer
11: Polarizer
12: protective layer
13: protective layer
20: retardation layer
100: polarizing plate with retardation layer

Claims (10)

A polarizing plate including a polarizer and a protective layer on at least a viewing side of the polarizer, and a retardation layer disposed on a side opposite to the viewing side of the polarizing plate,
The water vapor transmission rate of the protective layer on the visual side is 200 g/m 2 ·24 h or more, and is larger than the water vapor transmission rate of the retardation layer,
Polarizing plate with retardation layer. The method of claim 1,
A polarizing plate with a retardation layer, wherein the polarizing plate includes a protective layer only on a viewing side. 3. The method of claim 1 or 2,
A polarizing plate with a retardation layer, wherein a difference between the water vapor transmission rate of the protective layer on the visual side and the water vapor transmission rate of the retardation layer is 200 g/m 2 ·24 h or more. The method of claim 1,
The polarizing plate further includes another protective layer on the opposite side to the viewing side of the polarizer,
The water vapor transmission rate of the protective layer on the visual side is larger than the water vapor transmission rate of the smaller one of the water vapor transmission rate of the other protective layer and the water vapor transmission rate of the retardation layer;
Polarizing plate with retardation layer. 5. The method of claim 4,
A polarizing plate with a retardation layer, wherein the retardation layer is an alignment-solidified layer of a liquid crystal compound, and the water vapor transmission rate of the visual recognition side protective layer is larger than the water vapor transmission rate of the other protective layer. 6. The method according to claim 4 or 5,
A polarizing plate with a retardation layer, wherein a difference between the water vapor transmission rate of the visual recognition side protective layer and the water vapor transmission rate of the other protective layer and the water vapor transmission rate of the retardation layer is 200 g/m 2 ·24 h or more. 7. The method according to any one of claims 3 to 6,
The polarizing plate with a retardation layer whose water vapor transmission rate of the said other protective layer is 150 g/m<2>*24h or less. 8. The method according to any one of claims 1 to 7,
The polarizing plate with a retardation layer whose thickness of the said polarizer is 8 micrometers or less. 9. The method according to any one of claims 1 to 8,
A polarizing plate with a retardation layer whose total thickness is 20 micrometers or more and 100 micrometers or less. The organic electroluminescent display apparatus provided with the polarizing plate with retardation layer in any one of Claims 1-9.

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