WO2021070467A1

WO2021070467A1 - Phase difference layer-attached polarization plate and organic electro luminescence display device using same

Info

Publication number: WO2021070467A1
Application number: PCT/JP2020/030573
Authority: WO
Inventors: 寛友久; 後藤　周作; 一生田中
Original assignee: 日東電工株式会社
Priority date: 2019-10-10
Filing date: 2020-08-11
Publication date: 2021-04-15
Also published as: CN114502998A; KR20220076468A

Abstract

Provided is a phase difference layer-attached polarization plate which has remarkably suppressed decoloring when applied to an organic EL display device. This phase difference layer-attached polarization plate has: a polarization plate including a polarizer and a protective layer disposed at least on a viewing side of the polarizer; and a phase difference layer disposed on the reverse side of the viewing side of the polarization plate. The moisture permeability of the protective layer on the viewing side is at least 200 g/m²•24h, and is greater than the moisture permeability of the phase difference layer.

Description

Polarizing plate with retardation layer and organic electroluminescence display device using it

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

In recent years, with the spread of thin displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Since the organic EL panel has a highly reflective metal layer, problems such as reflection of external light and reflection of the background are likely to occur. Therefore, it is known that these problems can be prevented by providing a circular polarizing plate on the visual side (for example, Patent Documents 1 to 3). However, there is a problem that the circular polarizing plate provided in the organic EL display device is easily decolorized.

Japanese Unexamined Patent Publication No. 2003-31239 JP-A-2002-372622 Japanese Patent No. 3325560

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

The polarizing plate with a retardation layer of the present invention comprises a polarizing plate, a polarizing plate including a protective layer at least on the viewing side of the polarizing element, and a retardation layer arranged on the side opposite to the viewing side of the polarizing plate. Have. Moisture permeability of the protective layer of the viewing side is a 200g / m 2 · ^24h or more, greater than the moisture permeability of the retardation layer.
In one embodiment, the polarizing plate includes a protective layer only on the visual side.
In one embodiment, the difference between the moisture permeability of the moisture permeability and the retardation layer of the protective layer of the viewing side is 200g / m 2 · ^24h or more.
In one embodiment, the polarizing plate further includes another protective layer on the side opposite to the visible side of the polarizer, and the moisture permeability of the protective layer on the visible side is the moisture permeability of the other protective layer and the moisture permeability of the other protective layer. The moisture permeability of the retardation layer is larger than the smaller one. In one embodiment, the retardation layer is an orientation-solidified layer of a liquid crystal compound, and the moisture permeability of the protective layer on the visible side is larger than the moisture permeability of the other protective layer. In one embodiment, the difference between the moisture permeability of the protective layer on the visible side, the moisture permeability of the other protective layer, and the moisture permeability of the retardation layer, whichever is smaller, is 200 g / m ^2. It is 24 hours or more.
In one embodiment, the moisture permeability of the further protective layer is not more than 150g ^/ m 2 · 24h.
In one embodiment, the thickness of the polarizer is 8 μm or less.
In one embodiment, the total thickness of the polarizing plate with a retardation layer is 20 μm or more and 100 μm or less.
According to another aspect of the present invention, an organic electroluminescent display device is provided. This organic electroluminescence display device includes the above-mentioned polarizing plate with a retardation layer.

According to the embodiment of the present invention, in the polarizing plate with a retardation layer, the moisture permeability of the protective layer on the viewing side is the moisture permeability of the protective layer (if present) on the opposite side to the viewing side and the moisture permeability of the retardation layer. By making the moisture permeability larger than the smaller one, it is possible to realize a polarizing plate with a retardation layer in which decolorization is remarkably suppressed when applied to an organic EL display device.

It is schematic cross-sectional view of the polarizing plate with a retardation layer by one Embodiment of this invention.

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

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Refractive index (nx, ny, nz)
"Nx" is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
“Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) Angle When referring to an angle herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45 °" means ± 45 °.

A. Overall Configuration of Polarizing Plate with Difference Layer FIG. 1 is a schematic cross-sectional view of the polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example typically has a polarizing plate 10 and a retardation layer 20 in this order from the viewing side. The polarizing plate 10 includes a polarizing element 11 and a protective layer (visible side protective layer) 12 at least on the viewing side of the polarizing element 11. In the illustrated example, the protective layer (inner protective layer) 13 is provided on the side opposite to the visible side of the polarizer 11, but the protective layer 13 may be omitted depending on the purpose or the like. For example, if the retardation layer 20 is made of a stretched film of a resin film and can also serve as a protective layer for a polarizer, the protective layer 13 may be omitted. On the other hand, when the retardation layer 20 is an orientation-solidified layer of a liquid crystal compound, a protective layer 13 is typically provided. Practically, an adhesive layer (not shown) is provided on the side opposite to the polarizing plate 10 of the retardation layer 20 (that is, as the outermost layer on the side opposite to the viewing side), and the polarizing plate with the retardation layer is organic. It is said that it can be pasted on an EL cell. Further, it is preferable that a release film is temporarily adhered to the surface of the pressure-sensitive adhesive layer until a polarizing plate with a retardation layer is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be protected and a roll of the polarizing plate with a retardation layer can be formed.

In the embodiment of the present invention, the moisture permeability of the protective layer 12 is larger than the moisture permeability of the protective layer 13 (if present) and the moisture permeability of the retardation layer 20 whichever is smaller. Specifically: (1) When the protective layer 13 is omitted, the moisture permeability of the protective layer 12 is larger than the moisture permeability of the retardation layer 20; (2) When the protective layer 13 is present. , The moisture permeability of the protective layer 12 is larger than the moisture permeability of the protective layer 13 and the moisture permeability of the retardation layer 20, whichever is smaller; (3) The protective layer 13 is present and the retardation layer 20 is present. In the case of the oriented solidified layer of the liquid crystal compound, the moisture permeability of the protective layer 12 is larger than the moisture permeability of the protective layer 13. The present inventors faced a new problem that the polarizing plate with a retardation layer is decolorized when the polarizing plate with a retardation layer is applied to an organic EL display device, and as a result of diligent studies on the problem, the decolorization was performed. It was discovered that the cause was ammonia (substantially ammonium ions) generated from the organic EL panel. Furthermore, as a result of diligent studies on means for suppressing decolorization due to ammonia, the decolorization is remarkable by blocking the ammonium ions that have invaded the polarizer as much as possible and discharging the ammonium ions that have invaded as much as possible. I found that it can be suppressed. Based on these findings, by reducing the moisture permeability of the protective layer or retardation layer on the side opposite to the viewing side (organic EL panel side), ammonium ions that invade the polarizer are blocked as much as possible, and the viewing side (organic). By increasing the moisture permeability on the side far from the EL panel), it was possible to discharge as much ammonium ions as possible that had invaded, and this new problem was solved. The protective layer of the polarizer is designed to reduce the moisture permeability of the outer (visual side) protective layer because the main purpose is to protect the polarizer from moisture (water vapor). The embodiment of the present invention is based on such a technical idea completely opposite to the common general technical knowledge in the art.

The difference between the smaller moisture permeability of the moisture permeability and moisture permeability of the phase difference layer 20 of the moisture permeability and the protective layer 13 of the protective layer 12 (if present) is preferably 200g / m 2 · ^24h or more, more preferably 220g ^/ m 2 · 24h or more, more preferably 250g ^/ m 2 · 24h or more, and particularly preferably 300g ^/ m 2 · 24h or more. The upper limit of the difference may be, for example, 600g ^/ m 2 · 24h. When the difference is within such a range, decolorization of the polarizing plate with a retardation layer can be suppressed more satisfactorily.

Moisture permeability of the protective layer 12 is 200g ^/ m 2 · 24h or more, preferably 300g ^/ m 2 · 24h or more, more preferably 330g ^/ m 2 · 24h or more, more preferably 360 g / ^{m 2} · 24h or more, particularly preferably 400 g ^/ m 2 · 24h or more. The upper limit of the moisture permeability of the protective layer 12 may be, for example, 650g ^/ m 2 · 24h. Moisture permeability of the protective layer 13 is preferably not more than 150g ^/ m 2 · 24h, more preferably not more than 100g ^/ m 2 · 24h, more preferably at 70g ^/ m 2 · 24h or less, particularly preferably 50g / ^m is 2 · 24h or less. Moisture permeability of the protective layer 13 is preferably as low, the lower limit can be, for example, 5g ^/ m 2 · 24h. If the protective layer 13 is not present or, if the moisture permeability of the phase difference layer 20 is smaller than the moisture permeability of the protective layer 13, the moisture permeability of the retardation layer 20 is preferably not more than 150g / m 2 · ^24h, more preferably not more than 100g ^/ m 2 · 24h, more preferably less 70g ^/ m 2 · 24h, most preferably not more than 50g ^/ m 2 · 24h. Moisture permeability preferably as low retardation layer 20, the lower limit can be, for example, 5g ^/ 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 set the above difference in moisture permeability to a desired range. The moisture permeability can be measured according to JIS Z 0208.

The total thickness of the polarizing plate with a retardation layer is preferably 120 μm or less, more preferably 100 μm or less, and further preferably 80 μm 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 can have extremely excellent flexibility and bending durability. As a result, the polarizing plate with a retardation layer can be particularly preferably applied to a curved organic EL display device and / or a bendable or bendable organic EL display device.

The polarizing plate with a retardation layer may further include other optical functional layers. The type, characteristics, number, combination, arrangement position, and the like of the optical functional layers that can be provided on the polarizing plate with the retardation layer can be appropriately set according to the purpose. For example, the polarizing plate with a retardation layer may further have a conductive layer or an isotropic base material with a conductive layer (neither is shown). The conductive layer or the isotropic base material with the conductive layer is typically provided on the outside of the retardation layer 20 (opposite 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. .. Further, for example, the polarizing plate with a retardation layer may further include other retardation layers. The optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of other retardation layers can be appropriately set according to the purpose.

The polarizing plate with a retardation layer may be single-wafered or elongated. As used herein, the term "long" means an elongated shape having a length sufficiently long 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. Including. The long-shaped polarizing plate with a retardation layer can be wound in a roll shape.

Hereinafter, the components of the polarizing plate with a retardation layer will be described in more detail.

B. Polarizing plate B-1. Polarizer As the polarizer 11, any suitable polarizer can be adopted. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is used.

The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, it may be stretched and then dyed. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt on the surface of the PVA-based film and the blocking inhibitor, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying the resin base material. It is produced by forming a PVA-based resin layer on the resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. 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), and the resin substrate is peeled off from the resin substrate / polarizer laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, further preferably 10 μm or less, and particularly preferably 8 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance 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 degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

B-2. Protective Layer The visible side protective layer 12 and the inner protective layer 13 (if any) are each composed of any suitable film that can be used as a protective layer for the polarizer as long as it has the above-mentioned moisture permeability. Typical materials constituting the inner protective layer 13 include cycloolefin resins such as polycarbonate, (meth) acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polyester resins such as polyethylene terephthalate (PEN). Examples thereof include polyolefin resins such as polyethylene and polycarbonate resins. A typical example of the (meth) acrylic resin is a (meth) acrylic resin having a lactone ring structure. Examples of the (meth) acrylic resin having a lactone ring structure include JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005. It is described in Japanese Patent Application Laid-Open No. 146804. These publications are incorporated herein by reference. The inner protective layer 13 is preferably composed of a cycloolefin-based resin. Typical examples of the material constituting the visible side protective layer 12 include a cellulosic resin such as triacetyl cellulose (TAC) and a resin capable of forming a microporous film (for example, a polyurethane resin).

As will be described later, the polarizing plate with a retardation layer is typically arranged on the visible side of the organic EL display device, and the protective layer 12 is arranged on the visible side thereof. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary. Further / or, if necessary, the protective layer 12 is provided with a process for improving visibility when visually recognizing through polarized sunglasses (typically, a (elliptical) circularly polarized light function is provided, and an ultra-high phase difference is provided. May be given). By performing such a process, excellent visibility can be realized even when the display screen is visually recognized through a polarized lens such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can be suitably applied to an organic EL display device that can be used outdoors.

The thickness of the protective layer 12 can be appropriately set according to the desired moisture permeability. The thickness of the protective layer 12 is preferably 10 μm to 80 μm, more preferably 15 μm to 70 μm, and even more preferably 20 μm to 50 μm. When the surface treatment is applied, the thickness of the protective layer 12 is a thickness including the thickness of the surface treatment layer.

The protective layer 13 is preferably optically isotropic in one embodiment. As used herein, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. Say. The thickness of the protective layer 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, and even 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 thinning.

C. Phase difference layer The phase difference layer 20 may be a single layer or may have a laminated structure (substantially a two-layer structure).

When the retardation layer 20 is a single layer, the retardation layer 20 can typically function as a λ / 4 plate. The retardation layer is typically provided to impart antireflection characteristics to an organic EL display device. The retardation layer typically shows a relationship in which the refractive index characteristic is 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, and even more preferably 120 nm to 160 nm. Here, "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny> nz or ny <nz may occur within a range that does not impair the effects of the present invention.

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

When the retardation layer is a single layer, the retardation layer preferably exhibits a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, the 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 characteristics can be realized.

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

The retardation layer can be made of any suitable material as long as the above characteristics can be satisfied. Specifically, the retardation layer may be a stretched film of a resin film, or may be an orientation-solidifying layer of a liquid crystal compound (hereinafter, a liquid crystal alignment solidification layer).

When the retardation layer is a stretched film of a resin film, typical examples of the resin constituting the resin film include a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin). As the polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as the desired moisture permeability can be obtained. For example, the polycarbonate-based resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol, and an alkylene. Includes structural units derived from at least one dihydroxy compound selected from the group consisting of glycols or spiroglycols. Preferably, the polycarbonate-based resin is 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 an alicyclic dimethanol, and / or di, tri or polyethylene glycol. Includes structural units derived from; more preferably structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. .. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds, if necessary. The retardation layer can be formed by stretching a film made of the above-mentioned polycarbonate resin under arbitrary suitable stretching conditions. For details on the method for forming the polycarbonate resin and the retardation layer, see, for example, JP-A-2014-10291, JP-A-2014-226666, JP-A-2015-212816, JP-A-2015-212817. It is described in JP-A-2015-212818, JP-A-2017-54093, and JP-A-2018-60014. The descriptions in these publications are incorporated herein by reference.

When the retardation layer is a liquid crystal oriented solidified layer, the difference between nx and ny of the obtained retardation layer can be remarkably increased as compared with the non-liquid crystal material by using the liquid crystal compound, so that the desired surface can be obtained. The thickness of the retardation layer for obtaining the inner retardation can be remarkably reduced. As a result, it is possible to further reduce the thickness of the polarizing plate with a retardation layer (as a result, the organic EL display device). As used herein, the term "aligned solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the oriented state is fixed. The "oriented solidified layer" is a concept including an oriented cured layer obtained by curing a liquid crystal monomer. In the present embodiment, the rod-shaped liquid crystal compounds are typically oriented in a state of being aligned in the slow axis direction of the retardation layer (homogeneous orientation). Specific examples of the liquid crystal compound and details of the method for forming the liquid crystal oriented solidified layer are described in, for example, JP-A-2006-163343 and JP-A-2006-178389. The descriptions in these publications are incorporated herein by reference.

The thickness of the retardation layer can 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 can be, for example, 10 μm to 60 μm. When the retardation layer is a liquid crystal oriented solidification layer, the thickness of the retardation layer can be, for example, 1 μm to 5 μm.

When the retardation layer has a laminated structure, the retardation layer typically has a two-layer structure of a first liquid crystal oriented solidified layer and a second liquid crystal oriented solidified layer. In this case, either one of the first liquid crystal oriented solidified layer or the second liquid crystal oriented 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 oriented solidified layer can function as a λ / 2 plate and the second liquid crystal oriented solidified layer can function as a λ / 4 plate will be described, but these may be reversed. .. The thickness of the first liquid crystal oriented solidified layer can be adjusted so as to obtain a desired in-plane phase difference of the λ / 2 plate, and can be, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal oriented solidified layer can be adjusted so as to obtain the desired in-plane phase difference of the λ / 4 plate, and can be, for example, 1.0 μm to 2.5 μm. The in-plane retardation Re (550) of the first liquid crystal oriented solidified layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and further preferably 250 nm to 280 nm. As described above, the in-plane retardation Re (550) of the second liquid crystal oriented solidified layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and further preferably 120 nm to 160 nm. The angle formed by the slow axis of the first liquid crystal oriented solidified layer and the absorption axis of the polarizer is preferably 10 ° to 20 °, more preferably 12 ° to 18 °, and even more preferably about 15 °. Is. The angle formed by the slow axis of the second liquid crystal oriented solidified layer and the absorption axis of the polarizer is preferably 70 ° to 80 °, more preferably 72 ° to 78 °, and even more preferably about 75 °. Is. With such a configuration, it is possible to obtain characteristics close to the ideal reverse wavelength dispersion characteristic, and as a result, it is possible to realize extremely excellent antireflection characteristics.

D. Image display device The polarizing plate with a retardation layer according to the above items A to C can be applied to an organic EL display device. Therefore, an embodiment of the present invention includes an organic EL display device using such a polarizing plate with a retardation layer. The organic EL display device according to the embodiment of the present invention includes the polarizing plate with a retardation layer according to the above items A to C on the visible side thereof. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the organic EL cell side (the polarizing plate is on the visual recognition side). In one embodiment, the organic EL display device has a curved shape (substantially a curved display screen) and / or is bendable or bendable. As described above, when the polarizing plate with a retardation layer is applied to an organic EL display device, the present inventors use a polarizing plate with a retardation layer due to ammonia (substantially ammonium ions) generated from the organic EL panel. Discovered a new problem of decolorization, and solved the problem by the polarizing plate with a retardation layer according to the above items A to C. That is, in the organic EL display device, the effect of the polarizing plate with a retardation layer according to the embodiment of the present invention is remarkable.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" 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 meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).
(2) Single-unit transmittance and polarization degree The single-unit transmittance Ts and parallel transmittance measured using an ultraviolet-visible spectrophotometer (“LPF-2000” manufactured by Otsuka Electronics Co., Ltd.) for the polarizing plates used in Examples and Comparative Examples. The Tp and the orthogonal transmittance Tc were defined as the polarizers Ts, Tp and Tc, respectively. These Ts, Tp and Tc are Y values measured by the JIS Z8701 2 degree field of view (C light source) and corrected for luminosity factor. From the obtained Tp and Tc, the degree of polarization P was determined by the following formula.
Polarization degree P (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100
(3) Moisture Permeability Measured according to JIS Z 0208. Specifically, the protective layer or the retardation layer (the film constituting the layer) used in Examples and Comparative Examples was cut out in a circle of 10 cmΦ and used as a measurement sample. The moisture permeability of this measurement sample was measured using "MOCON" manufactured by Hitachi, Ltd. under the test conditions of 40 ° C. and 92% RH.
(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 mouth (upper end) of the glass bottle was about 30 mm. The polarizing plates with retardation layers obtained in Examples and Comparative Examples were cut out to a size of 15 mm × 15 mm, and an adhesive layer was provided on the retardation layer side to use as measurement data. The measurement material was attached to the edge of the mouth of the glass bottle via the adhesive layer so that the mouth of the glass bottle was completely covered with this measurement material and steam did not leak through the gap. The glass bottle covered with the measurement material was heated at 60 ° C. for 2 hours. ΔP was calculated from the following formula _{, where P 0 was} the degree of polarization of the polarizing plate with a retardation layer (substantially, the polarizer) before _{heating and P 20} was the degree of polarization after heating. The smaller ΔP, the more the decolorization by ammonia is suppressed.
ΔP = P ₂₀ −P ₀

[Example 1]
1. 1. Preparation of Polarizer As the thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape, a water absorption of 0.75%, and a Tg of about 75 ° C. was used. One side of the resin base material was corona-treated.
100 weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") are mixed at a ratio of 9: 1. A PVA aqueous solution (coating solution) was prepared by dissolving 13 parts by weight of potassium iodide in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm to prepare a laminate.
The obtained laminate was uniaxially stretched at the free end 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the finally obtained polarizing film was placed in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water). Immersion was carried out for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) was 43.0% (dyeing treatment).
Then, it was immersed in a cross-linked bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight) at a liquid temperature of 70 ° C., the rolls having different peripheral speeds are subjected to the longitudinal direction (longitudinal direction). ) Was uniaxially stretched so that the total stretching ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75 ° C. for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the laminated body by the drying shrinkage treatment was 5.2%.
In this way, a polarizer having a thickness of 5 μm was formed on the resin base material.

2. Preparation of Polarizing Plate An HC-TAC film was attached to the surface of the polarizer of the resin base material / polarizer laminate obtained above via an ultraviolet curable adhesive. Specifically, the curable adhesive was coated so as to have a thickness of 1.0 μm, and bonded using a roll machine. Then, UV light was irradiated from the HC-TAC film side to cure the adhesive. The HC-TAC film is a film in which a hard coat (HC) layer (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film is attached so as to be on the polarizer side. I matched it. Next, the resin base material was peeled off, and a cycloolefin-based resin film (thickness 13 μm: hereinafter, COP film) was attached to the peeled surface in the same manner as described above. Moisture permeability of HC-TAC film was 427g ^/ m 2 · 24h, moisture permeability of the COP film was 35g ^/ m 2 · 24h. In this way, a polarizing plate having a structure of a visible side protective layer (HC-TAC film) / a polarizer / another protective layer (COP film) was obtained.

3. 3. Preparation of retardation film constituting the retardation layer 3-1. Polymerization of polyester carbonate-based resin Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. Bis [9- (2-phenoxycarbonylethyl) fluorene-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 parts by weight (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by weight (0.298 mol) and calcium acetate monohydrate 1.19 × ^{10 -2} parts by weight as a catalyst (6.78 × 10 ^{- 5} mol) was charged. After substituting nitrogen under reduced pressure in the reactor, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was adjusted to 13.3 kPa 90 minutes after reaching 220 ° C. The phenol vapor produced as a by-product of the polymerization reaction was guided 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 guided to a condenser at 45 ° C. for recovery. Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.

3-2. Preparation of retardation film After vacuum-drying the obtained polyester carbonate resin (pellets) at 80 ° C for 5 hours, a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 ° C), T-die (width 200 mm) , Set temperature: 250 ° C.), chill roll (set temperature: 120 to 130 ° C.), and a film forming apparatus equipped with a winder was used to prepare a long resin film having a thickness of 135 μm. The obtained long resin film was stretched in the width direction at a stretching temperature of 133 ° C. and a stretching ratio of 2.8 times to obtain a retardation film having a thickness of 47 μm. The Re (550) of the obtained retardation film was 141 nm, the Re (450) / Re (550) was 0.82, and the Nz coefficient was 1.12. Further, the moisture permeability of the obtained retardation film was 75g ^/ m 2 · 24h.

4. Fabrication of polarizing plate with retardation layer 2. On the surface of another protective layer (COP film) of the polarizing plate obtained in 3. above. The retardation film obtained in (1) was bonded via an acrylic pressure-sensitive adhesive (thickness: 5 μm). At this time, the absorption axis of the polarizer and the slow axis of the retardation film were bonded so as to form an angle of 45 °. In this way, a polarizing plate with a retardation layer having a structure of a visible side protective layer (HC-TAC film) / a polarizer / another protective layer (COP film) / an adhesive layer / a retardation layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 112 μm. Further, the obtained polarizing plate with a retardation layer was subjected to the evaluation of (4) above. The results are shown in Table 1.

[Example 2]
1. 1. Preparation of Polarizing Plate A polarizing plate was prepared in the same manner as in Example 1.

2. Preparation of liquid crystal oriented solidified layer constituting the 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 cyclopenta. After adding to 400 parts of non (CPN), heat to 60 ° C. to dissolve by stirring, and after confirmation of dissolution, return to room temperature, and return to room temperature, 3 parts of Irgacure 907 (manufactured by BASF Japan Co., Ltd.), Megafuck F- 0.2 part of 554 (manufactured by DIC Corporation) and 0.1 part of p-methoxyphenol (MEHQ) were added, and the mixture was further stirred to obtain a solution. The solution was clear and uniform. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, a polyimide solution for an alignment film was applied to a glass substrate having a thickness of 0.7 mm by a spin coating method, dried at 100 ° C. for 10 minutes, and then fired at 200 ° C. for 60 minutes to obtain a coating film. .. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to a base material (substantially an alignment film) by a spin coating method, and dried at 100 ° C. for 2 minutes. The obtained coating film was cooled to room temperature and then irradiated with ultraviolet rays at an intensity of 30 ^{mW / cm 2 for 30 seconds using a high-pressure mercury lamp to obtain a liquid crystal oriented solidified layer.} The in-plane retardation Re (550) of the liquid crystal oriented solidified layer was 130 nm. The Re (450) / Re (550) of the liquid crystal oriented solidified layer was 0.851, showing the inverse dispersion wavelength characteristic.

3. 3. Fabrication of polarizing plate with retardation layer 1. On the surface of another protective layer (COP film) of the polarizing plate obtained in 2. above. The liquid crystal oriented solidified layer obtained in the above was transferred. At this time, transfer (bonding) was performed so that the angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal oriented solidified layer was 45 °. The transfer (bonding) was carried out via an ultraviolet curable adhesive (thickness 1.0 μm). In this way, polarized light with a retardation layer having a structure of a visible side protective layer (HC-TAC film) / a polarizing element / another protective layer (COP film) / an adhesive layer / a retardation layer (liquid crystal oriented solidifying layer). I got a board. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that a separate protective layer was not provided. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Examples 4 to 6]
A polarizing plate with a retardation layer was obtained with the structure shown in Table 1 for the viewing side protective layer, the polarizer, another protective layer, and the retardation layer. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A resin base material / polarizer laminate was produced in the same manner as in Example 1. An HC-COP film was attached to the surface of the polarizer of the obtained resin base material / polarizer laminate in the same manner as in Example 1. The HC-COP film is a film in which a hard coat (HC) layer (thickness 2 μm) is formed on a COP film (thickness 25 μm), and the COP film is bonded so as to be on the polarizer side. Next, the resin base material was peeled off, and a COP film similar to that in Example 1 was attached to the peeled surface in the same manner as in Example 1. Moisture permeability of HC-COP film is 17g ^/ m 2 · 24h, moisture permeability of the COP film was 35g ^/ m 2 · 24h. In this way, a polarizing plate having a structure of a visible side protective layer (HC-COP film) / a polarizer / another protective layer (COP film) was obtained. The following procedure was the same as in Example 1 to obtain a polarizing plate with a retardation layer. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Examples 2 to 10]
A polarizing plate with a retardation layer was obtained with the structure shown in Table 1 for the viewing side protective layer, the polarizer, another protective layer, and the retardation layer. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Evaluation]
As is clear from Table 1, according to the examples 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 decolorize) even when exposed to ammonia. That is, according to the embodiment of the present invention, it can be seen that a polarizing plate with a retardation layer in which decolorization is suppressed can be realized when applied to an organic EL display device. On the other hand, the polarizing plate with a retardation layer in the comparative example has a significantly reduced polarization function, and the majority of the polarizing plates have almost no polarization function.

The polarizing plate with a retardation layer of the present invention is suitably used as an antireflection circular polarizing plate of an organic EL display device.

10 Polarizing plate 11 Polarizer 12 Protective layer 13 Protective layer 20 Phase difference layer 100 Polarizing plate with retardation layer

Claims

It has a polarizing element, a polarizing plate including a protective layer at least on the viewing side of the polarizing element, and a retardation layer arranged on the side opposite to the viewing side of the polarizing plate.
Moisture permeability of the protective layer of the viewing side is at 200g / m 2 · 24h or more, greater than the moisture permeability of the retardation layer,
Polarizing plate with retardation layer.
The polarizing plate with a retardation layer according to claim 1, wherein the polarizing plate includes a protective layer only on the visual side.
The difference between the moisture permeability of the moisture permeability of the viewer side protective layer and the retardation layer is the 200 g / m 2 · 24h or more, according to claim 1 or 2 retardation layer with the polarizing plate according to.
The polarizing plate further includes another protective layer on the side opposite to the visible side of the polarizer.
The moisture permeability of the protective layer on the visual side is larger than the moisture permeability of the other protective layer and the moisture permeability of the retardation layer, whichever is smaller.
The polarizing plate with a retardation layer according to claim 1.
The polarizing plate with a retardation layer according to claim 4, wherein the retardation layer is an orientation-solidified layer of a liquid crystal compound, and the moisture permeability of the protective layer on the visible side is larger than the moisture permeability of the other protective layer.
The difference between the smaller moisture permeability of the moisture permeability of the moisture permeability and the retardation layer of the further protective layer and moisture permeability of the protective layer of the viewing side is a 200g / m 2 · 24h or more, claim 4. The polarizing plate with a retardation layer according to 4 or 5.
It said further moisture permeability of the protective layer is not more than 150g / m 2 · 24h, the phase difference layer with a polarizing plate according to any of claims 3 to 6.
The polarizing plate with a retardation layer according to any one of claims 1 to 7, wherein the thickness of the polarizer is 8 μm or less.
The polarizing plate with a retardation layer according to any one of claims 1 to 8, wherein the total thickness is 20 μm or more and 100 μm or less.
An organic electroluminescence display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 9.