CN116529803A

CN116529803A - Polarizing plate with retardation layer and organic electroluminescent display device using same

Info

Publication number: CN116529803A
Application number: CN202180078043.XA
Authority: CN
Inventors: 沟端骏; 友久宽; 后藤周作
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2020-11-20
Filing date: 2021-07-28
Publication date: 2023-08-01
Also published as: WO2022107394A1; KR20230106612A; JP2022081990A; TW202229013A

Abstract

The present invention provides a polarizing plate with a retardation layer which can significantly inhibit discoloration when applied to an organic EL display device. The polarizing plate with a retardation layer according to an embodiment of the present invention comprises a polarizer and a barrier layer disposed on one side of the polarizer and including the retardation layer, wherein the barrier layer has an ammonia gas transmission rate of 70g/m ² 24h or less.

Description

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

Technical Field

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

Background

In recent years, with the popularization of thin displays, displays (organic EL display devices) having organic EL panels mounted thereon have been proposed. Since the organic EL panel has a metal layer with high reflectivity, problems such as reflection of external light and reflection of background are likely to occur. Accordingly, it is known to prevent these problems by providing a circularly polarizing plate on the viewing side (for example, patent document 1 and patent document 2). However, the circularly polarizing plate provided in the organic EL display device has a problem of easy discoloration.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2002-372622

Patent document 2: japanese patent No. 3325560

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above-described conventional problems, and a main object of the present invention is to provide a polarizing plate with a retardation layer that can significantly suppress discoloration when applied to an organic EL display device.

Means for solving the problems

According to an embodiment of the present invention, a polarizing plate with a retardation layer is provided. The polarizing plate with a retardation layer comprises a polarizer and a barrier layer disposed on one side of the polarizer and comprising a retardation layer, wherein the barrier layer has an ammonia gas transmission rate of 70g/m ² 24h or less.

In one embodiment, the ammonia gas permeation amount of the retardation layer is 70g/m ² 24h or less.

In one embodiment, the barrier layer comprises a protective layer of the polarizer.

In one embodiment, the ammonia gas of the protective layer has a permeability of 70g/m ² 24h or less.

In one embodiment, the polarizing plate with a retardation layer has a protective layer disposed on the other side of the polarizer.

In one embodiment, the polarizer has a single transmittance of 40% or more and 45% or less.

In one embodiment, re (450)/Re (550) of the retardation layer is 0.8 or more and less than 1.

In one embodiment, the polarizer has a thickness of 10 μm or less.

In one embodiment, the thickness of the polarizing plate with a retardation layer is 150 μm or less.

According to another aspect of the present invention, an organic electroluminescent display device is provided. The organic electroluminescent display device has the polarizing plate with a retardation layer described above.

Effects of the invention

According to the embodiment of the present invention, by providing a layer satisfying a predetermined transmission amount of ammonia on one side of the polarizer, the polarizing plate with the retardation layer, which can significantly suppress discoloration when applied to an organic EL display device, can be realized.

Drawings

Fig. 1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate with a retardation layer according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view schematically showing a state in which a polarizing plate with a retardation layer is disposed on an organic EL panel in an organic EL display device according to an embodiment of the present invention.

Detailed Description

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

(definition of terms and symbols)

The definitions of terms and symbols in the present specification are as follows.

(1) Refractive index (nx, ny, nz)

"nx" is a refractive index in a direction in which the in-plane refractive index becomes maximum (i.e., a slow axis direction), "ny" is a refractive index in a direction orthogonal to the slow axis (i.e., a fast axis direction), and "nz" is a refractive index in a thickness direction.

(2) In-plane phase difference (Re)

"Re (λ)" is the in-plane retardation measured by light having a wavelength of λnm at 23 ℃. For example, "Re (550)" is the in-plane retardation measured at 23℃by light having a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), re (λ) passes through the formula: re (λ) = (nx-ny) ×d.

(3) Retardation in thickness direction (Rth)

"Rth (λ)" is a phase difference in the thickness direction measured by light having a wavelength of λnm at 23 ℃. For example, "Rth (550)" is a phase difference in the thickness direction measured at 23℃by light having a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), rth (λ) is represented by the formula: rth (λ) = (nx-nz) ×d.

(4) Nz coefficient

The Nz coefficient is obtained by nz=rth/Re.

(5) Angle of

In the present specification, when referring to an angle, the angle includes both clockwise and counterclockwise with respect to a reference direction. Thus, for example, "45" means ± 45 °.

A. Polarizing plate with phase difference layer

Fig. 1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate with a retardation layer according to an embodiment of the present invention. The polarizing plate 100 with a retardation layer includes a polarizer 11, a protective layer (visible side protective layer) 12 disposed on the visible side of the polarizer 11, and a blocking layer 30 disposed on the opposite side of the polarizer 11 from the visible side. The blocking layer 30 includes, in order from the visible side, a protective layer (inner protective layer) 13 of the polarizer 11 and the retardation layer 20. As described above, the protective layer 13 is disposed on the opposite side of the polarizer 11 from the visible side, but the protective layer 13 may be omitted depending on the purpose or the like. Specifically, the barrier layer 30 may not include the protective layer 13. For example, in the case where the retardation layer 20 is formed 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 alignment cured layer of a liquid crystal compound, the protective layer 13 is typically disposed. The retardation layer 20 may be a single layer or may have a laminated structure in which two or more layers are laminated. The laminate of the polarizer and the protective layer is referred to as a polarizing plate. In the illustrated example, the polarizer 10 has a polarizer 11 and protective layers 12, 13.

The thickness of the polarizing plate with a retardation layer (the thickness from the visible side protective layer to the retardation layer) is preferably 150 μm or less, more preferably 120 μm or less, still more preferably 100 μm or less, particularly preferably 80 μm or less. The lower limit of the thickness of the polarizing plate with a retardation layer is preferably 20 μm, more preferably 45 μm. Such a polarizing plate with a retardation layer can have excellent flexibility and bending durability, for example. As a result, the polarizing plate with the retardation layer can be applied to an organic EL display device that can be bent, flexed, folded, wound, or the like.

Although not shown, the polarizing plate with a retardation layer may further have another functional layer. The kind, characteristics, number, combination, arrangement, and the like of the functional layers that the polarizing plate with a retardation layer can have 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 substrate with a conductive layer. The polarizing plate with a retardation layer having a conductive layer or an isotropic substrate with a conductive layer is applicable to, for example, an organic EL display device incorporating a touch sensor inside an organic EL panel. As another example, the polarizing plate with a retardation layer may further have another retardation layer. The optical characteristics (for example, refractive index characteristics, in-plane retardation, nz coefficient, photoelastic coefficient), thickness, arrangement, and the like of the other retardation layers can be appropriately set according to the purpose. As a specific example, another retardation layer (typically, a layer imparting (elliptical) polarization function, a layer imparting ultra-high retardation) that improves visibility when viewed through polarized sunglasses may be provided on the visible side of the polarizing plate 10. By having such a layer, excellent visibility can be achieved even when a display screen is visualized through a polarized lens such as polarized sunglasses. Therefore, the obtained polarizing plate (polarizing plate with retardation layer) can be suitably used for an image display device which can be used outdoors.

The members constituting the polarizing plate with the retardation layer may be laminated via any suitable adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. Specifically, the retardation layer 20 may be bonded to the polarizer 11 or the protective layer 13 via an adhesive layer (preferably, an active energy ray-curable adhesive) or may be bonded to the polarizer 11 or the protective layer 13 via an adhesive layer (for example, an acrylic adhesive). When the retardation layer 20 has a laminated structure of two or more layers, the respective retardation layers are bonded, for example, via an adhesive layer (preferably, an active energy ray-curable adhesive is used). The blocking layer 30 may include an adhesive layer disposed between the polarizer 11 and the retardation layer 20.

Although not shown, in practical use, an adhesive layer is provided on the opposite side of the retardation layer 20 to the side on which the polarizer 11 is disposed (specifically, as the outermost layer on the opposite side from the viewing side), and a polarizing plate with a retardation layer is made to be attachable to the organic EL panel body. Further, a release film (separator) is preferably temporarily attached to the surface of the pressure-sensitive adhesive layer before the polarizing plate with the retardation layer is used. By temporarily attaching the release film, the adhesive layer can be protected, and a roll of the polarizing plate with the retardation layer can be formed.

The polarizing plate with the retardation layer may be elongated or monolithic. Here, the term "long" refers to an elongated shape having a length sufficiently long with respect to the width, and for example, refers to an elongated shape having a length 10 times or more, preferably 20 times or more, with respect to the width. The elongated polarizing plate with the retardation layer may be wound into a roll.

A-1 Barrier layer

The ammonia permeation amount of the barrier layer 30 was 70g/m ² 24 hours or less, preferably 60g/m ² 24 hours or less, more preferably 50g/m ² 24 hours or less, more preferably 40g/m ² 24 hours or less, particularly preferably 30g/m ² 24h or less. By providing such a barrier layer, discoloration can be significantly suppressed. The present inventors have made intensive studies on a new problem of decoloring a polarizing plate with a retardation layer when the polarizing plate with a retardation layer is applied to an organic EL display device, and as a result, have found that: the cause of the discoloration is ammonia (substantially ammonium ions) originating from members constituting the organic EL panel. General purpose medicineBy blocking ammonia reaching the polarizer 11 as much as possible by such a barrier layer 30, discoloration can be significantly suppressed. Specifically, decomposition of a dichroic substance (typically, an iodine complex) contained in the polarizer can be suppressed. The permeation amount of ammonia gas through the barrier layer 30 is, for example, 3.0g/m ² 24h or more.

The ammonia gas permeation amount of the barrier layer 30 may be satisfied by at least one layer contained in the barrier layer 30, or may be satisfied by a combination of 2 or more layers contained in the barrier layer 30. Specifically, the ammonia gas permeation amount of the barrier layer 30 may be achieved by the protective layer 13 of the polarizer 11, may be achieved by the retardation layer 20, may be achieved by the adhesive layer (for example, an adhesive layer), or may be achieved by a combination of these. In one embodiment, the ammonia gas permeation amount of both or either of the retardation layer 20 and the protective layer 13 is 70g/m ² 24h or less.

The ammonia gas permeation amount can be determined by measuring the ammonia water permeation amount and the water permeation amount from the difference between them.

A-2 polarizer

The polarizer is typically a film containing a dichroic substance (typically iodine).

For example, from the viewpoint of thickness reduction, 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 still more preferably 3 μm or more. If the thickness of the polarizer is in such a range, curling at the time of heating can be well suppressed, and good durability of appearance at the time of heating can be obtained, for example.

The polarizer preferably exhibits absorption dichroism at any one of wavelengths 380nm to 780 nm. The monomer transmittance of the polarizer is, for example, 40.0% or more, preferably 41.5% or more, more preferably 43.0% or more, and still more preferably 44.5% or more. On the other hand, the monomer transmittance may be, for example, 46.0% or less, or 45.0% or less. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

The polarizer may be made by any suitable method. Specifically, the polarizer may be made of a single-layer resin film, or may be made of a laminate of two or more layers.

A typical method for producing a polarizer from the single-layer resin film includes a dyeing treatment and a stretching treatment of the resin film with a dichroic substance such as iodine or a dichroic dye. As the resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially methylalized PVA film, or an ethylene-vinyl acetate copolymer partially saponified film is used. The polarizer is preferably obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film, in view of excellent optical characteristics.

The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing or may be performed while dyeing. In addition, dyeing may be performed after stretching. The PVA-based film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like as needed. For example, by immersing the PVA-based film in water and washing it with water before dyeing, not only stains and anti-blocking agents on the surface of the PVA-based film can be washed away, but also the PVA-based film can be swelled to prevent uneven dyeing.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, and a polarizer obtained by coating a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be obtained by, for example, forming a PVA-based resin layer on the resin substrate by applying a PVA-based resin solution on the resin substrate and drying the same; the laminate was stretched and dyed to prepare a polarizer from the PVA-based resin layer. In the present embodiment, it is preferable to form a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Further, the stretching may further include if necessary, subjecting the laminate to air stretching at a high temperature (for example, 95 ℃ or higher) before stretching in an aqueous boric acid solution. In the present embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction and is shrunk by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes sequentially subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, an in-water stretching treatment, and a drying shrinkage treatment. By introducing the auxiliary stretching, even when PVA is coated on the thermoplastic resin, crystallinity of PVA can be improved, and high optical characteristics can be achieved. Further, by simultaneously improving the orientation of PVA in advance, problems such as lowering of the orientation of PVA and dissolution can be prevented when immersed in water in the subsequent dyeing step and stretching step, and high optical characteristics can be achieved. Further, when the PVA-based resin layer is immersed in a liquid, disturbance of orientation of polyvinyl alcohol molecules and decrease of orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This improves the optical characteristics of the polarizer obtained by the treatment step of immersing the laminate in a liquid, such as dyeing treatment or underwater stretching treatment. Further, by shrinking the laminate in the width direction by the drying shrinkage treatment, the optical characteristics can be improved. The resulting laminate of the resin substrate and the polarizer may be used as it is (that is, the resin substrate may be used as the protective layer of the polarizer), or any suitable protective layer according to the purpose may be laminated on the release surface or the surface opposite to the release surface after the resin substrate is released from the laminate of the resin substrate and the polarizer. Details of such a method for producing a polarizer are described in, for example, japanese patent application laid-open No. 2012-73580 and japanese patent No. 6470455. The entire disclosures of these publications are incorporated by reference into this specification.

A-3 protective layer

The protective layer may be formed of any suitable film that can be used as a protective layer for a polarizer. Examples of the material constituting the protective layer include cellulose resins such as triacetyl cellulose (TAC), cycloolefin resins such as polynorbornene, (meth) acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. As a representative example of the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure is given. (meth) acrylic resins having a lactone ring structure are described in, for example, JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005-146084. These publications are incorporated by reference into this specification.

The polarizing plate with a retardation layer is typically disposed on the viewing side of the organic EL display device, and the viewing side protective layer 12 may be subjected to surface treatments such as a hard coat treatment, an antireflection treatment, a release treatment, and an antiglare treatment, as necessary.

The thickness of the visible side protective layer 12 can be set appropriately. The thickness of the visible side protective layer 12 is preferably 10 μm to 80 μm, more preferably 15 μm to 70 μm, and still more preferably 20 μm to 50 μm. In the case of performing the surface treatment, the thickness of the visible side protective layer 12 is a thickness including the thickness of the surface treatment layer.

In one embodiment, the protective layer 13 has an ammonia permeation rate of 70g/m ² 24 hours or less, preferably 60g/m ² 24 hours or less, more preferably 50g/m ² 24 hours or less, more preferably 40g/m ² 24 hours or less, particularly preferably 30g/m ² 24h or less. In this case, as a material constituting the protective layer 13, at least 1 selected from the group consisting of cellulose-based resins, cycloolefin-based resins, and polyester-based resins is preferably used.

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 0nm to 10nm, and the retardation Rth (550) in the thickness direction is-10 nm to +10nm. The thickness of the protective layer 13 can be appropriately set in accordance with a desired ammonia gas permeation amount, for example. The thickness of the protective layer 13 is preferably 10 μm to 80 μm, more preferably 20 μm to 70 μm, and still more preferably 30 μm to 50 μm. In the case where the retardation layer 20 is a stretched film of a resin film, the protective layer 13 may be omitted from the viewpoint of, for example, thickness reduction.

A-4 phase difference layer

The retardation 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 typically functions as a λ/4 plate. The retardation layer is typically provided to impart an antireflection property to the organic EL display device. The refractive index characteristics of the retardation layer typically show a relationship of nx > ny=nz. The in-plane retardation Re (550) of the retardation layer is preferably 100nm to 190nm, more preferably 110nm to 170nm, and still more preferably 120nm to 160nm. Here, "ny=nz" includes not only the case where ny is completely equal to nz but also the case where ny is substantially equal to nz. Therefore, ny > nz or ny < nz may be used in some cases within a range that does not impair the effects of the present invention.

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

When the phase difference layer is a single layer, the phase difference layer preferably exhibits an inverse dispersion wavelength characteristic in which the phase difference value increases according to 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, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be achieved.

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 in such a range, an organic EL display device having very excellent antireflection characteristics can be obtained by forming the phase difference layer into a λ/4 plate as described above.

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

In the case where the retardation layer is a stretched film of a resin film, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin) is exemplified as a representative example of the resin constituting the resin film. Any suitable polycarbonate resin may be used as long as the desired moisture permeability is obtained. For example, the polycarbonate resin contains a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanol, diethylene glycol, triethylene glycol or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from alicyclic dimethanol, and/or a structural unit derived from diethylene glycol, triethylene glycol, or polyethylene glycol; it is further preferable that the composition contains 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 diethylene glycol, triethylene glycol or polyethylene glycol. The polycarbonate resin may contain a structural unit derived from another dihydroxy compound, if necessary. The retardation layer can be formed by stretching a film made of the polycarbonate resin described above under any suitable stretching conditions. Details of the method for forming the polycarbonate resin and the retardation layer are described in, for example, japanese patent application laid-open No. 2014-10291, japanese patent application laid-open No. 2014-2666, japanese patent application laid-open No. 2015-212816, japanese patent application laid-open 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 disclosures of these publications are incorporated by reference into this specification.

In the case where the retardation layer is a liquid crystal alignment cured layer, the difference between nx and ny of the obtained retardation layer can be increased significantly compared with a non-liquid crystal material by using a liquid crystal compound, and therefore the thickness of the retardation layer for obtaining a desired in-plane retardation can be reduced excessively. As a result, the polarizing plate with the retardation layer (as a result, the organic EL display device) can be further thinned. In the present specification, the "alignment cured layer" is a layer in which a liquid crystal compound is aligned in a predetermined direction in a layer and the alignment state thereof is fixed. The term "alignment cured layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer. In this embodiment, the rod-like liquid crystal compound is typically aligned (parallel alignment) in a state of being aligned along the slow axis direction of the retardation layer. Specific examples of the liquid crystal compound and details of the method for forming the liquid crystal alignment cured layer are described in, for example, japanese patent application laid-open No. 2006-163343 and Japanese patent application laid-open No. 2006-178389. The disclosures of these publications are incorporated by reference into this specification.

The thickness of the retardation layer may be typically set to a thickness that can function properly as a λ/4 plate. In the case where 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. In the case where the retardation layer is a liquid crystal alignment cured layer, the thickness of the retardation layer may be, for example, 1 μm to 5 μm.

In the case where the retardation layer 20 has a laminated structure, the retardation layer typically has a 2-layer structure of a 1 st liquid crystal alignment cured layer and a 2 nd liquid crystal alignment cured layer. In this case, either one of the 1 st liquid crystal alignment cured layer or the 2 nd liquid crystal alignment cured layer may function as a λ/2 plate, and the other may function as a λ/4 plate. Here, the description will be given of the case where the 1 st liquid crystal alignment cured layer can function as a λ/2 plate and the 2 nd liquid crystal alignment cured layer can function as a λ/4 plate, but the opposite may be true. The thickness of the 1 st liquid crystal alignment cured layer may be adjusted so as to obtain a desired in-plane retardation of the lambda/2 plate, and may be, for example, 2.0 μm to 4.0 μm. The thickness of the 2 nd liquid crystal alignment cured layer may be adjusted so as to obtain a desired in-plane retardation of the λ/4 plate, and may be, for example, 1.0 μm to 2.5 μm. The in-plane phase difference Re (550) of the 1 st liquid crystal alignment cured layer is preferably 200nm to 300nm, more preferably 230nm to 290nm, and still more preferably 250nm to 280nm. The in-plane phase difference Re (550) of the 2 nd liquid crystal alignment cured layer is preferably 100nm to 190nm, more preferably 110nm to 170nm, and still more preferably 120nm to 160nm as described above. The angle between the slow axis of the 1 st liquid crystal alignment cured 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 2 nd liquid crystal alignment cured layer and the absorption axis of the polarizer is preferably 70 ° to 80 °, more preferably 72 ° to 78 °, and still more preferably about 75 °. With such a configuration, characteristics close to ideal inverse wavelength dispersion characteristics can be obtained, and as a result, very excellent antireflection characteristics can be realized.

In one embodiment, the ammonia gas permeation amount of the retardation layer 20 is 70g/m ² 24 hours or less, preferably 60g/m ² 24 hours or less, more preferably 50g/m ² 24 hours or less, more preferably 40g/m ² 24 hours or less, particularly preferably 30g/m ² 24h or less. In this case, as the retardation layer 20, a stretched film of the above resin film is preferably used. As a constituent material of the protective layer 13 combined with the retardation layer 20 which is a stretched film of the resin film, at least 1 selected from cycloolefin-based resins and polyester-based resins is preferably used. According to such a combination, discoloration can be extremely remarkably suppressed.

As a constituent material of the protective layer 13 combined with the retardation layer 20 which is a liquid crystal alignment cured layer, a cellulose resin is preferably used. According to such a combination, discoloration can be extremely remarkably suppressed.

B. Organic EL display device

The polarizing plate with a retardation layer described above can be applied to an organic EL display device. Accordingly, the organic EL display device according to the embodiment of the present invention has the above-described polarizing plate with a retardation layer.

Fig. 2 is a schematic cross-sectional view schematically showing a state in which a polarizing plate with a retardation layer is disposed on an organic EL panel in an organic EL display device according to an embodiment of the present invention. The polarizing plate 100 with a retardation layer is arranged such that the blocking layer 30 is on the organic EL panel main body 40 side of the polarizer 11. Specifically, the polarizing plate 100 with a retardation layer is attached to the organic EL panel main body 40 via an adhesive layer (not shown). The organic EL panel body 40 has a substrate 60, and an upper structure layer 80 including a circuit layer including a Thin Film Transistor (TFT) or the like, an Organic Light Emitting Diode (OLED), a sealing film sealing the OLED, and the like. In the upper structural layer 80, for example, a nitrogen-containing layer (for example, a nitride layer) is included, and ammonia (ammonia ions) can be generated from the upper structural layer 80. According to the above polarizing plate with a retardation layer, discoloration can be significantly suppressed in an organic EL display device. In addition, the problem of decoloring can be solved without designing and changing the structure of the organic EL panel main body.

For example, when a flexible substrate (for example, a resin substrate) is used as the substrate 60, the obtained organic EL display device can be bent, flexed, folded, wound, or the like.

Examples

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 weight basis.

(1) Thickness of (L)

The thickness of 10 μm or less was measured by an interferometer film thickness meter (product name "MCPD-3000" manufactured by Otsuka electronics Co., ltd.). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by ANRITSU Co., ltd., product name "KC-351C").

(2) Permeation amount of ammonia gas

Two cups A, B were prepared, 150g of a 10% aqueous ammonia solution was added to cup A, 150g of water was added to cup B, and the mixture was sealed with a test piece (film) cut into a round shape having a diameter of 6cm, and in this state, cup A, B was left to stand in an oven (at atmospheric pressure) set at 40℃for 24 hours, and the weight change of cup A, B before and after the standing was measured. Calculate the weight change of cup A (ammonia and oxygen)The amount of permeation of water) and the weight change amount of the cup B (amount of permeation of water), the amount of permeation of ammonia gas (g/m) ² ·24h)。

Example 1

1. Manufacture of polarizer

As the thermoplastic resin base material, an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) having a long form, a water absorption of 0.75% and a Tg of about 75℃was used. Corona treatment is performed on one side of the resin base material.

In the case of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (trade name "GOHSEFIMERZ410" manufactured by Japanese synthetic chemical Co., ltd.) were used in the following manner: 1 to 100 parts by weight of the PVA-based resin mixed in the above step, 13 parts by weight of potassium iodide was added, and the resultant was dissolved in water to prepare a PVA aqueous solution (coating liquid).

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

The resulting laminate was subjected to free-end uniaxial stretching to 2.4 times in the machine direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ℃.

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

Next, the film was immersed in a dyeing bath (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) at a liquid temperature of 30 ℃ for 60 seconds while adjusting the concentration so that the monomer transmittance (Ts) of the finally obtained polarizing film became 43.0% (dyeing treatment).

Then, the resultant mixture was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40℃for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4.0 wt% and potassium iodide: 5.0 wt%) at a liquid temperature of 70 ℃ and uniaxially stretched (in-water stretching treatment) between rolls having different peripheral speeds so that the total stretching ratio became 5.5 times in the longitudinal direction.

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20 ℃.

After that, the resultant was dried in an oven maintained at 90℃and then contacted with a SUS-made heating roller maintained at 75℃in surface temperature for about 2 seconds (drying shrinkage treatment). The shrinkage in the width direction of the laminate by the drying shrinkage treatment was 5.2%.

In this way, a polarizer having a thickness of 5 μm was formed on the resin substrate.

2. Manufacture of polarizer

The polarizer surface of the laminate of the resin substrate/polarizer obtained in the above was bonded to a TAC film having a thickness of 25 μm via an ultraviolet curable adhesive. Specifically, the cured adhesive was coated so that the thickness of the cured adhesive became 1.0 μm, and the cured adhesive was bonded by a roll machine. Then, UV light is irradiated from the TAC film side to harden the adhesive. Next, the resin substrate was peeled off from the polarizer, and a cycloolefin resin film (thickness 13 μm, permeability of ammonia: 54g/m ² 24h: the following, COP films). In this manner, a polarizing plate having a structure of TAC film/polarizer/COP film was obtained.

3. Fabrication of retardation film constituting retardation layer

3-1 polymerization of polyester carbonate resin

The polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with stirring wings and a reflux cooler controlled at 100 ℃. Adding bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl]29.60 parts by mass (0.046 mol) of methane, 29.21 parts by mass (0.200 mol) of Isosorbide (ISB), 42.28 parts by mass (0.139 mol) of Spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC) and 1.19X10 of calcium acetate monohydrate as a catalyst ^-2 Parts by mass (6.78X10) ^-5 mol). After the reduced pressure nitrogen substitution in the reactor, the reactor was warmed with a heat medium and at an internal temperatureStirring was started at the point of reaching 100 ℃. After 40 minutes from the start of the temperature increase, the internal temperature was controlled to 220℃and the pressure was reduced to 13.3kPa for 90 minutes after the start of the temperature increase. The phenol vapor produced as a by-product of the polymerization reaction was introduced into a reflux condenser at 100℃and some of the monomer components contained in the phenol vapor were returned to the reactor, and the uncondensed phenol vapor was introduced into a condenser at 45℃and recovered. After nitrogen was introduced into the 1 st reactor and once repressed to atmospheric pressure, the oligomerization reaction liquid in the 1 st reactor was transferred to the 2 nd reactor. Then, the temperature rise and pressure reduction in the 2 nd reactor were started, and the internal temperature was set at 240℃and the pressure at 0.2kPa for 50 minutes. Thereafter, polymerization is carried out until a predetermined stirring power is reached. Nitrogen was introduced into the reactor at the time of reaching the predetermined power and the pressure was again applied, and the polyester carbonate resin thus produced was extruded into water, and the strands were cut to obtain pellets.

3-2 preparation of phase-difference film

The obtained polyester-carbonate resin (pellets) were dried in vacuo at 80℃for 5 hours, and then a film-forming apparatus comprising a single screw extruder (cylinder set temperature: 250 ℃ C. Manufactured by Toshiba machine Co., ltd.), a T-die (width: 200mm, set temperature: 250 ℃ C.), a chilled roll (set temperature: 120 to 130 ℃ C.) and a winder was used to prepare a resin film in the form of a long film having a thickness of 135. Mu.m. The obtained long resin film was stretched at a stretching temperature of 133℃and a stretching ratio of 2.8 times in the width direction to obtain a retardation film having a thickness of 47. Mu.m. The Re (550) of the obtained retardation film was 141nm, re (450)/Re (550) was 0.82, and the nz coefficient was 1.12. In addition, the ammonia gas permeability of the obtained retardation film was 10g/m ² ·24h。

4. Preparation of the adhesive

4-1 preparation of acrylic Polymer

Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, a monomer mixture containing 91 parts of butyl acrylate, 6 parts of Acryloylmorpholine (ACMO), 2.7 parts of acrylic acid, and 0.3 part of 4-hydroxybutyl acrylate was charged. Further, 0.1 part of 2,2' -azobisisobutyronitrile as a polymerization initiator was charged together with 100 parts of ethyl acetate with respect to 100 parts of the monomer mixture, nitrogen was introduced while stirring slowly to replace nitrogen, and then the polymerization was carried out by maintaining the liquid temperature in the flask at about 55℃for 8 hours to prepare an acrylic polymer solution.

4-2 preparation of the adhesive

To 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 part of trimethylolpropane/tolylene diisocyanate adduct (trade name "Coronate L" manufactured by Tosoh corporation), 0.3 part of peroxide crosslinking agent (benzoyl peroxide) and 0.2 part of epoxy group-containing silane coupling agent (trade name "KBM-403" manufactured by Xinyue chemical industry Co., ltd.) were blended to obtain a pressure-sensitive adhesive. The ammonia gas permeability of the resulting adhesive (thickness 20 μm) was 118g/m ² ·24h。

5. Production of polarizing plate with retardation layer

The COP film surface of the polarizing plate obtained in the above 2 was bonded to the retardation film obtained in the above 3 via the adhesive (thickness: 20 μm) obtained in the above 4. At this time, the polarizer was attached so that the absorption axis of the polarizer and the slow axis of the retardation film form an angle of 45 °. In this manner, a polarizing plate with a retardation layer was obtained.

Example 2

For the production of the polarizing plate, a PET film (thickness: 30 μm, permeation of ammonia gas: 53g/m was used ² 24 h) in the same manner as in example 1 except that the COP film was replaced, a polarizing plate with a retardation layer was obtained.

Example 3

In the production of the polarizing plate, a TAC film (thickness: 25 μm, ammonia permeation amount: 30g/m ² 24 h) in the same manner as in example 1 except that the COP film was replaced, a polarizing plate with a retardation layer was obtained.

Example 4

In the production of the polarizing plate, an acrylic film having a lactone ring structure (thickness: 20 μm, ammonia transmission of 78g/m ² 24 h) in the same manner as in example 1 except that the COP film was replaced, a polarizing plate with a retardation layer was obtained.

Example 5

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the COP film was bonded to the polarizer without using an ultraviolet curable adhesive in the production of the polarizing plate.

Example 6

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the following liquid crystal alignment cured layer was used as the retardation layer.

(production of liquid Crystal alignment cured layer constituting phase-Shift 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) were added to 400 parts of Cyclopentanone (CPN), and after heating to 60℃and stirring to dissolve the compound, the solution was returned to room temperature after confirming the dissolution, 3 parts of Irgacure 907 (manufactured by BASF Japan Co., ltd.), 0.2 part of MEGAFAC F-554 (manufactured by DIC Co., ltd.) and 0.1 part of p-Methoxyphenol (MEHQ) were added thereto and further stirred to obtain a solution. The solution was transparent and homogeneous. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, the polyimide solution for an alignment film was applied to a glass substrate having a thickness of 0.7mm by spin coating, dried at 100℃for 10 minutes, and then baked at 200℃for 60 minutes, thereby obtaining a coating film. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The friction treatment was performed using a commercially available friction device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating, and dried at 100℃for 2 minutes. After cooling the resulting coating film to room temperature, a high-pressure mercury lamp was used at 30mW/cm ² The liquid crystal alignment cured layer was obtained by irradiating the liquid crystal alignment cured layer with an ultraviolet ray for 30 seconds Zhong Zi. The in-plane retardation Re (550) of the obtained liquid crystal alignment cured layer was 130nm, re (450)/Re (550) was 0.851, and the liquid crystal alignment cured layer exhibited an inverse dispersion wavelength characteristic. In addition, the ammonia gas permeability of the resulting liquid crystal alignment cured layer was 103g/m ² ·24h。

[ chemical formula 1]

[ chemical formula 2]

Example 7

In the production of the polarizing plate, a TAC film (thickness: 25 μm, ammonia permeation amount: 30g/m ² 24 h) instead of COP film; and, a polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the liquid crystal alignment cured layer was used as the retardation layer, and an ultraviolet-curable adhesive (thickness 1.0 μm) was used instead of the adhesive when the polarizing plate was bonded to the retardation layer.

Comparative example 1

In the production of the polarizing plate, a TAC film having a thickness of 40 μm was used instead of the TAC film having a thickness of 25. Mu.m, and an acrylic film having a lactone ring structure (thickness of 20 μm, permeability of ammonia gas of 78g/m was used ² 24 h) instead of COP film; a polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the liquid crystal alignment cured layer was used as the retardation layer.

Comparative example 2

In the production of the polarizing plate, a TAC film having a thickness of 40 μm was used instead of the TAC film having a thickness of 25 μm; a polarizing plate with a retardation layer was obtained in the same manner as in example 5, except that the liquid crystal alignment cured layer was used as the retardation layer.

Comparative example 3

In the production of the polarizing plate, an acrylic film (thickness: 20 μm) having a lactone ring structure was used instead of the TAC film having a thickness: 25 μm, and an acrylic film (thickness: 20 μm, permeation of ammonia: 78 g/m) having a lactone ring structure was used ² 24 h) instead of COP film; a polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the liquid crystal alignment cured layer was used as the retardation layer.

The following evaluations were performed for examples and comparative examples. The evaluation results are summarized in table 1 together with the configuration of the polarizing plate with a retardation layer (barrier layer).

< evaluation >

Monomer transmittance and polarization degree

For the polarizers of examples and comparative examples, the single transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc measured by using an ultraviolet-visible spectrophotometer (LPF-2000 made by the tsuka electronics agency) were set as Ts, tp, and Tc of the polarizer, respectively. These Ts, tp, and Tc are Y values measured by a 2-degree field of view (C light source) of JISZ8701 and subjected to visibility correction. From the obtained Tp and Tc, the polarization degree P is obtained by the following formula.

The polarization degree P (%) = { (Tp-Tc)/(tp+tc) } ^1/2 ×100

Ammonia decolorization test

10g of 10% aqueous ammonia solution was added to a glass bottle (cylindrical shape having a diameter of 30mm and a depth of 50 mm), and the opening of the glass bottle was covered with the polarizing plate with retardation layer obtained in examples and comparative examples (the retardation layer was in contact with the opening) and sealed, and the glass bottle was heated at 65℃for 2 hours in this state. After heating, the degree of polarization of the portion corresponding to the opening of the glass bottle was measured, the degree of polarization before heating of the polarizing plate with the retardation layer (substantially, polarizer) was set to P, the degree of polarization after heating was set to P', and Δp was calculated from the following formula. The smaller Δp means that discoloration caused by ammonia is suppressed more.

ΔP＝P-P’

TABLE 1

In the examples, a polarizing plate with a retardation layer was obtained, in which Δp was less than 20% and the degree of polarization was not substantially changed (not decolored) even when exposed to ammonia. On the other hand, in the comparative example, it was also confirmed that the degree of polarization was greatly reduced and the polarization function was substantially lost.

Industrial applicability

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

Description of symbols

10. Polarizing plate

11. Polarizer

12. Protective layer (visible side protective layer)

13. Protective layer (inner protective layer)

20. Phase difference layer

30. Barrier layer

100. Polarizing plate with phase difference layer

Claims

1. A polarizing plate with a retardation layer, comprising:

a polarizer; and

a blocking layer disposed on one side of the polarizer and including a phase difference layer;

the ammonia gas permeability of the barrier layer is 70g/m ² 24h or less.

2. The polarizing plate with a retardation layer as claimed in claim 1, wherein the ammonia gas permeation amount of the retardation layer is 70g/m ² 24h or less.

3. The polarizing plate with a phase difference layer according to claim 1 or 2, wherein the blocking layer comprises a protective layer of the polarizer.

4. The polarizing plate with a retardation layer as claimed in claim 3, wherein the protective layer has a transmission amount of ammonia gas of 70g/m ² 24h or less.

5. The polarizing plate with a retardation layer according to any one of claims 1 to 4, which has a protective layer disposed on the other side of the polarizer.

6. The polarizing plate with a retardation layer as claimed in any one of claims 1 to 5, wherein the single body transmittance of the polarizer is 40% or more and 45% or less.

7. The polarizing plate with a retardation layer as claimed in any one of claims 1 to 6, wherein Re (450)/Re (550) of the retardation layer is 0.8 or more and less than 1.

8. The polarizing plate with a retardation layer as claimed in any one of claims 1 to 7, wherein the thickness of the polarizer is 10 μm or less.

9. The polarizing plate with a retardation layer as claimed in any one of claims 1 to 8, having a thickness of 150 μm or less.

10. An organic electroluminescent display device having the polarizing plate with a retardation layer as claimed in any one of claims 1 to 9.