CN114578469A - Polarizing plate with optical compensation layer and organic EL panel using the polarizing plate with optical compensation layer - Google Patents

Abstract

The invention provides a polarizing plate with an optical compensation layer, which has excellent anti-reflection characteristics in an oblique direction while maintaining excellent anti-reflection characteristics in a front direction, and has a neutral hue in the oblique direction. The polarizing plate with an optical compensation layer of the present invention is used for an organic EL panel. The polarizing plate with the optical compensation layer is provided with a polarizer, a first optical compensation layer and a second optical compensation layer in sequence. The first optical compensation layer exhibits a refractive index characteristic of nx > nz > ny, and Re (550) is 220nm to 300 nm. The second optical compensation layer exhibits a refractive index characteristic of nx > nz > ny, and Re (550) is from 90nm to 170 nm. Re (450) and Re (550) of the first optical compensation layer and the second optical compensation layer are substantially equal.

Description

Polarizing plate with optical compensation layer and organic EL panel using the polarizing plate with optical compensation layer

technical field

The present invention relates to a polarizer with an optical compensation layer and an organic EL panel using the polarizer with an optical compensation layer.

Background technique

In recent years, with the spread of thin displays, displays (organic EL display devices) mounted with organic EL panels 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 to prevent these problems by disposing the circularly polarizing plate on the visual confirmation side. As a general circularly polarizing plate, a circularly polarizing film obtained by laminating a retardation film (typically, a λ/4 plate) so that the slow axis of the retardation film forms an angle of about 45° with respect to the absorption axis of the polarizer is known. piece. In addition, in order to further improve the antireflection properties, attempts have been made to laminate retardation films (optical compensation layers) having various optical properties. As this retardation film, for example, a retardation film satisfying Re(550)>Re(450) is known. The circularly polarizing plate using such a retardation film can be expected to improve the viewing angle characteristics of an organic EL panel. However, such a retardation film has problems that it is expensive and the cost of producing a circularly polarizing plate is high.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent No. 3325560

SUMMARY OF THE INVENTION

The problem to be solved by the invention

The present invention has been made in order to solve the above-mentioned conventional problems, and its main object is to provide inexpensive and excellent anti-reflection characteristics in the front direction and also excellent in the anti-reflection characteristics in the oblique direction, and further realize that the hue in the oblique direction can be Polarizer with optical compensation layer for neutral organic EL panel.

means to solve the problem

The polarizing plate with an optical compensation layer of the present invention can be used for an organic EL panel. The polarizer with an optical compensation layer includes a polarizer, a first optical compensation layer, and a second optical compensation layer in this order. The first optical compensation layer and the second optical compensation layer respectively show the refractive index characteristics of nx>nz>ny. Furthermore, Re(450) and Re(550) of each of the first optical compensation layer and the second optical compensation layer are substantially equal. In one embodiment, Re(550) is 220nm～300nm, Nz coefficient is 0.4～0.8, and the angle formed by the absorption axis direction of the polarizer and the slow axis direction of the first optical compensation layer is 5°～25° . In addition, the Re(550) of the second optical compensation layer is 90 nm to 170 nm, the Nz coefficient is 0.4 to 0.8, and the angle formed between the absorption axis direction of the polarizer and the slow axis direction of the second optical compensation layer is 65 °～85°. Here, Re(450) and Re(550) represent the in-plane retardation measured with light having wavelengths of 450 nm and 550 nm at 23° C., respectively.

In one embodiment, the Re(550) of the first optical compensation layer is 280 nm to 360 nm, the Nz coefficient is 0.5 to 0.9, and the absorption axis direction of the polarizer and the slow axis direction of the first optical compensation layer are formed. The angles are substantially parallel. In addition, the Re(550) of the second optical compensation layer is 100 nm to 180 nm, the Nz coefficient is 0.2 to 0.6, and the angle formed between the absorption axis direction of the polarizer and the slow axis direction of the second optical compensation layer is 35 °～55°.

According to other aspects of the present invention, an organic EL panel is provided. This organic EL panel includes the above-mentioned polarizing plate with an optical compensation layer.

Invention effect

According to the present invention, in the polarizer with an optical compensation layer, the first optical compensation layer and the second optical compensation layer are arranged in order from the polarizer side, and the first optical compensation layer exhibits a refraction of nx>nz>ny The second optical compensation layer exhibits a refractive index characteristic of nx>nz>ny and has a predetermined in-plane retardation, and provides the first optical compensation layer and the second optical compensation layer. All layers are composed of retardation films with flat dispersion, which can be inexpensive and excellent in anti-reflection properties in the oblique direction while maintaining the excellent anti-reflection properties in the front direction, and can achieve an organic neutral hue in the oblique direction. Polarizer with optical compensation layer for EL panel.

Description of drawings

1 is a schematic cross-sectional view of a polarizing plate with an optical compensation layer according to an embodiment of the present invention.

Symbol Description

10 Polarizer

20 protective layer

30 The first optical compensation layer

40 Second optical compensation layer

100 Polarizers with Optical Compensation Layer

Detailed ways

Hereinafter, preferred 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 in this specification are as follows.

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

"nx" is the refractive index in the direction where the in-plane refractive index is the largest (ie, the slow axis direction), "ny" is the refractive index in the in-plane direction orthogonal to the slow axis (ie, the fast axis direction), "nz" ” is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. Re(λ) is obtained by the formula: Re=(nx−ny)×d when the thickness of the layer (film) is set to d (nm). For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C.

(3) Phase difference in thickness direction (Rth)

"Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. Rth(λ) is obtained by the formula: Rth=(nx−nz)×d when the thickness of the layer (film) is set to d (nm). For example, "Rth(550)" is the retardation in the thickness direction measured by light having a wavelength of 550 nm at 23°C.

(4) Nz coefficient

The Nz coefficient is obtained by Nz=Rth/Re.

(5) Substantially orthogonal or parallel

The expressions "substantially orthogonal" and "substantially orthogonal" include the case where the angle formed by the two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±5°. The expressions "substantially parallel" and "substantially parallel" include the case where the angle formed by the two directions is 0°±10°, preferably 0°±7°, and more preferably 0°±5°. Further, in this specification, when referring to "orthogonal" or "parallel", a state of being substantially orthogonal or substantially parallel may be included.

A. Overall composition of polarizer with optical compensation layer

1 is a schematic cross-sectional view of a polarizing plate with an optical compensation layer according to an embodiment of the present invention. The polarizing plate 100 with an optical compensation layer of the present embodiment includes a polarizer 10 , a first optical compensation layer 30 , and a second optical compensation layer 40 in this order. In practical terms, the protective layer 20 may be provided on the opposite side of the polarizer 10 from the first optical compensation layer 30 as in the illustrated example. In addition, the polarizer with an optical compensation layer may include another protective layer (also referred to as an inner protective layer) between the polarizer 10 and the first optical compensation layer 30 . In the illustrated example, the inner protective layer is omitted. In this case, the first optical compensation layer 30 can also function as an inner protective layer. In addition, a conductive layer and a substrate (both not shown) can be sequentially provided on the opposite side of the second optical compensation layer 40 to the first optical compensation layer 30 (ie, outside the second optical compensation layer 40 ) as required. The base material and the conductive layer are closely laminated. In this specification, "adhesive lamination" means that two layers are directly and fixedly laminated without intervening an adhesive layer (eg, an adhesive bond layer, a pressure-sensitive adhesive layer). The conductive layer and the base material can be typically introduced into the polarizing plate 100 with an optical compensation layer in the form of a laminate of the base material and the conductive layer. By further providing a conductive layer and a substrate, the polarizer 100 with an optical compensation layer can be applied to an internal touch panel type input display device. Further/or, if necessary, the polarizing plate with an optical compensation layer (substantially the protective layer 20) may be subjected to a process for improving the visibility when visually confirming through polarized sunglasses (representatively, imparting (elliptical) polarization to the polarizer. Optical function, giving ultra-high phase difference). By implementing such a process, even when the display screen is visually confirmed through polarized lenses such as polarized sunglasses, excellent visibility can be achieved. Therefore, the polarizing plate with an optical compensation layer can also be applied to an image display device which can be used outdoors.

The respective refractive index characteristics of the first optical compensation layer 30 and the second optical compensation layer 40 show a relationship of nx>nz>ny and have a slow axis. Furthermore, Re(450) and Re(550) of each of the first optical compensation layer and the second optical compensation layer are substantially equal. That is, each of the first optical compensation layer and the second optical compensation layer has a flat dispersion characteristic in which the retardation value hardly changes with the change in the wavelength of the measurement light. In one embodiment, the in-plane retardation Re(550) of the first optical compensation layer 30 is 220 nm to 300 nm. In this case, the Nz coefficient of the first optical compensation layer is 0.4 to 0.8, and the angle formed by the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 is 5° to 25°, preferably 8° ~22°, more preferably 12° to 18°, further preferably about 15°.

Furthermore, the in-plane retardation Re(550) of the second optical compensation layer 40 is 90 nm to 170 nm. In this case, the Nz coefficient of the second optical compensation layer is 0.4 to 0.8, and the angle formed by the slow axis of the second optical compensation layer 30 and the absorption axis of the polarizer 10 is 65° to 85°, preferably 68° ~82°, more preferably 72° to 78°, further preferably about 75°. In another embodiment, the in-plane retardation Re(550) of the first optical compensation layer 30 of the first optical compensation layer 30 is preferably 280 nm to 360 nm. In this case, the Nz coefficient of the first optical compensation layer is preferably 0.5 to 0.9, and the angle formed by the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 is preferably substantially parallel. Further, the in-plane retardation Re(550) of the second optical compensation layer 40 is preferably 100 nm to 180 nm. In this case, the Nz coefficient of the second optical compensation layer is preferably 0.2 to 0.6, and the angle formed between the slow axis of the second optical compensation layer 30 and the absorption axis of the polarizer 10 is preferably 35° to 55°, more preferably It is 38° to 52°, more preferably 42° to 48°, and particularly preferably about 45°. As described above, the first optical compensation layer exhibiting the refractive index characteristic of nx>nz>ny and having a predetermined in-plane retardation, and the first optical compensation layer exhibiting the refractive index characteristic of nx>nz>ny and The second optical compensation layer having a predetermined in-plane retardation, and both the first optical compensation layer and the second optical compensation layer are made of a retardation film with flat dispersion, thereby maintaining the excellent circularly polarized light function. It has excellent anti-reflection properties in the frontal direction, and can prevent light leakage and the like caused by the apparent axis shift of the absorption axis of the polarizer when viewed from an oblique direction. As a result, when a polarizing plate with an optical compensation layer is applied to an organic EL panel, excellent antireflection properties can be achieved in the oblique direction, and further neutrality in the oblique direction (that is, no undesired tinted) hue.

Hereinafter, each layer and optical film constituting the polarizing plate with an optical compensation layer will be described in detail.

A-1. Polarizer

As the polarizer 10, any appropriate polarizer can be employed. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of a single-layer resin film include polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. A polarizer obtained by dyeing and stretching with dichroic substances such as iodine and dichroic dyes, dehydration of PVA, and dehydrochlorination of polyvinyl chloride such as polyene-based alignment films and the like. From the viewpoint of being excellent in optical properties, it is preferable to use a polarizer obtained by uniaxially stretching a PVA-based film by dyeing it with iodine.

The above-mentioned dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, 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 necessary. For example, washing with water by immersing the PVA-based film in water before dyeing can not only wash away the stains and anti-blocking agent on the surface of the PVA-based film, but also swell the PVA-based film to prevent uneven dyeing.

Specific examples of polarizers obtained by using a laminate include a laminate using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and coating The polarizer obtained by the laminated body of the PVA-type resin layer formed in this resin base material. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, by applying a PVA-based resin solution on the resin substrate and making it By drying and forming a PVA-based resin layer on the resin substrate, a laminate of the resin substrate and the PVA-based resin layer is obtained; this laminate is stretched and dyed to make the PVA-based resin layer a polarizer. In the present embodiment, the stretching typically includes stretching the laminate by immersing it in an aqueous solution of boric acid. Furthermore, the stretching may further include in-air stretching of the laminate at a high temperature (eg, 95° C. or higher) before stretching in a boric acid aqueous solution, if necessary. The obtained laminate of resin substrate/polarizer may be used as it is (that is, the resin substrate may be used as a protective layer of the polarizer), or the resin substrate may be removed from the laminate of resin substrate/polarizer. It is peeled and used by laminating any appropriate protective layer according to the purpose on the peeling surface. The details of the manufacturing method of such a polarizer are described in Unexamined-Japanese-Patent No. 2012-73580 (Japanese Patent No. 5414738 ), for example. The entire contents of this publication are incorporated herein by reference.

The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, further preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. As long as the thickness of the polarizer is within such a range, curling during heating can be suppressed favorably, and favorable appearance durability during heating can be obtained.

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

A-2. First Optical Compensation Layer

As described above, in the case of the first optical compensation layer 30, the refractive index characteristic shows a relationship of nx>nz>ny and has a slow axis. Furthermore, the first optical compensation layer exhibits a flat wavelength dispersion characteristic in which the retardation value hardly changes with the change in the wavelength of the measurement light. Specifically, Re(450)/Re(550) of the first optical compensation layer is preferably 0.99 to 1.03. A retardation film exhibiting flat wavelength dispersion characteristics is less expensive than a retardation film exhibiting reverse dispersion characteristics, so by adopting a configuration like the embodiment of the present invention, an inexpensive and excellent optical characteristic with optical compensation can be obtained layer of polarizer.

The in-plane retardation Re(550) of the first optical compensation layer 30 is 220 nm to 300 nm, preferably 230 nm to 290 nm, and more preferably 250 nm to 270 nm. As long as the in-plane retardation of the first optical compensation layer is within such a range, the slow axis direction of the first optical compensation layer is set to 5° to 25° with respect to the absorption axis direction of the polarizer as described above (especially is about 15°), it is possible to prevent the reduction of the antireflection function in the oblique direction due to the apparent axis shift of the absorption axis of the polarizer. Furthermore, in this case, in one embodiment, the Nz coefficient of the first optical compensation layer is 0.4 to 0.8, preferably 0.5 to 0.7, more preferably 0.55 to 0.65, and particularly preferably 0.55 to 0.60. As long as the Nz coefficient is within such a range, by adjusting the angle between the slow axis of the first optical compensation layer and the absorption axis of the polarizer to a predetermined angle, more excellent antireflection characteristics in the oblique direction can be achieved.

In another embodiment, the in-plane retardation Re(550) of the first optical compensation layer is preferably 280 nm to 360 nm, more preferably 290 nm to 350 nm, and even more preferably 310 nm to 330 nm. As long as the in-plane retardation of the first optical compensation layer is within such a range, by setting the slow axis direction of the first optical compensation layer to preferably be substantially parallel to the absorption axis direction of the polarizer, it is possible to prevent polarization caused by The apparent axis shift of the absorption axis of the device reduces the antireflection function in the oblique direction. Furthermore, in this case, in another embodiment, the Nz coefficient is preferably 0.5 to 0.9, more preferably 0.6 to 0.8, still more preferably 0.7 to 0.8, and particularly preferably 0.72 to 0.78. As long as the Nz coefficient is within such a range, by adjusting the angle between the slow axis of the first optical compensation layer and the absorption axis of the polarizer to a predetermined angle, more excellent antireflection characteristics in the oblique direction can be achieved.

The first optical compensation layer is typically formed of a resin film formed of any appropriate resin capable of achieving the above-mentioned properties. Examples of resins forming the resin film include polycarbonate-based resins, cyclic olefin-based resins, cellulose-based resins, polyester-based resins, polyvinyl alcohol-based resins, polyamide-based resins, and polyimides. resin, polyether resin, polystyrene resin, acrylic resin, polyester carbonate resin. Among these, a cyclic olefin-based resin or a polycarbonate-based resin can be appropriately used.

Cyclic olefin-based resins are a general term for resins in which cyclic olefins are polymerized as polymer units, and examples thereof include those described in Japanese Patent Laid-Open No. 1-240517, Japanese Patent Laid-Open No. 3-14882, and Japanese Patent Laid-Open No. 3-122137. The resins described in the official gazette. Specific examples include ring-opening (copolymer) polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymers of cyclic olefins and α-olefins such as ethylene and propylene (representatively random copolymers) and graft-modified products obtained by modifying them with unsaturated carboxylic acids and their derivatives, and their hydrogenated products. Specific examples of cyclic olefins include norbornene-based monomers. As the norbornene-based monomer, the monomers described in Japanese Patent Laid-Open No. 2015-210459 and the like can be exemplified. Various products of the said cyclic olefin resin are marketed. Specific examples include: "ZEONEX", "ZEONOR" manufactured by Japan's ZEON Corporation, "Arton" manufactured by JSR Corporation, "TOPAS" manufactured by TICONA, and "TOPAS" manufactured by Mitsui Chemicals "APEL".

As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained. Preferably, the polycarbonate resin contains a structural unit derived from an isosorbide-based dihydroxy compound and a structural unit derived from the group consisting of alicyclic diol, alicyclic dimethanol, diethylene glycol, triethylene glycol, or polyethylene glycol, and Structural unit of at least one dihydroxy compound of alkylene glycol or spiroglycol. More preferably, the polycarbonate resin contains a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and/or a structural unit derived from diethylene glycol, triethylene glycol, or polyethylene glycol. Structural units. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as needed. In addition, the details of the manufacturing method of the polycarbonate resin and retardation film which can be used suitably in this invention are described in, for example, International Publication No. 2011/062239, and this description is incorporated in this specification as a reference.

The first optical compensation layer can be formed, for example, by coating a shrinkable film with a coating liquid obtained by dissolving or dispersing the above-mentioned resin in any appropriate solvent to form a coating film, and shrinking the coating film. Typically, as for the shrinkage of the coating film, the shrinkable film is shrunk by heating the laminate of the shrinkable film and the coating film, and the coating film is shrunk by such shrinkage of the shrinkable film. The shrinkage rate of the coating film is preferably 0.50 to 0.99, more preferably 0.60 to 0.98, and further preferably 0.70 to 0.95. The heating temperature is preferably 130°C to 170°C, and more preferably 150°C to 160°C. In one embodiment, when shrinking the coating film, the laminate may be stretched in a direction orthogonal to the shrinking direction. In this case, the draw ratio of the laminate is preferably 1.01 times to 3.0 times, more preferably 1.05 times to 2.0 times, and even more preferably 1.10 times to 1.50 times. Specific examples of the material constituting the shrinkable film include polyolefin, polyester, acrylic resin, polyamide, polycarbonate, norbornene resin, polystyrene, polyvinyl chloride, polyvinylidene chloride, fiber Plain resin, polyethersulfone, polysulfone, polyimide, polyacrylic acid, acetate resin, polyarylate, polyvinyl alcohol, liquid crystal polymer. They can be used alone or in combination. The shrinkable film is preferably a stretched film formed of these materials.

The thickness of the first optical compensation layer is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and further preferably 20 μm to 60 μm. With such a thickness, the desired in-plane retardation and Nz coefficient described above can be obtained.

A-3. Second Optical Compensation Layer

As described above, in the case of the second optical compensation layer 40, the refractive index characteristic shows the relationship of nx>nz>ny and has a slow axis. In addition, the first optical compensation layer exhibits a flat wavelength dispersion characteristic in which the retardation value hardly changes with the wavelength of the measurement light. Specifically, Re(450)/Re(550) of the first optical compensation layer is preferably 0.99 to 1.03. A retardation film exhibiting flat wavelength dispersion characteristics is less expensive than a retardation film exhibiting reverse dispersion characteristics, so by adopting a configuration like the embodiment of the present invention, an inexpensive and excellent optical characteristic with optical compensation can be obtained layer of polarizer.

As described above, the in-plane retardation Re(550) of the second optical compensation layer 40 is 90 nm to 170 nm, preferably 100 nm to 160 nm, and more preferably 120 nm to 140 nm. As long as the in-plane retardation of the second optical compensation layer is in such a range, it is set so as to be an angle of 65° to 85° (particularly about 75°) with respect to the absorption axis direction of the polarizer as described above. The direction of the slow axis of the second optical compensation layer can achieve excellent anti-reflection properties. Furthermore, in this case, in one embodiment, the Nz coefficient of the second optical compensation layer is 0.4 to 0.8, preferably 0.5 to 0.7, more preferably 0.55 to 0.65, and particularly preferably 0.57 to 0.63. A better reflection hue can be achieved.

In another embodiment, as described above, the in-plane retardation Re(550) of the second optical compensation layer 40 is preferably 100 to 180 nm, more preferably 110 to 170 nm, and even more preferably 130 to 150 nm. As long as the in-plane retardation of the second optical compensation layer is in such a range, as described above, it is preferable to set an angle of 35° to 55° (especially preferably about 45°) with respect to the absorption axis direction of the polarizer. By setting the slow axis direction of the second optical compensation layer, excellent antireflection properties can be achieved. In addition, in this case, the Nz coefficient is preferably 0.2 to 0.6, more preferably 0.3 to 0.5, still more preferably 0.35 to 0.45, and particularly preferably 0.37 to 0.42. A better reflection hue can be achieved.

The material for forming the second optical compensation layer and the formation method of the second optical compensation layer are the same as the first optical compensation layer.

The thickness of the second optical compensation layer is preferably 10 μm to 150 μm, more preferably 10 μm to 100 μm, and further preferably 10 μm to 30 μm. With such a thickness, the desired in-plane retardation and Nz coefficient described above can be obtained,

By combining the first optical compensation layer described in the above A-2. and the second optical compensation layer described in this A-3., it is possible to obtain an inexpensive and oblique direction while maintaining excellent antireflection properties in the front direction. It is also excellent in antireflection properties, and can realize a polarizing plate with an optical compensation layer of an organic EL panel whose hue in the oblique direction is neutral.

A-4. Protective layer

The protective layer 20 is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material used as the main component of the film include cellulose-based resins such as cellulose triacetate (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, Transparent resins such as polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based. In addition, thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone-based resins or ultraviolet curable resins may also be mentioned. Wait. In addition to this, for example, glass-based polymers such as siloxane-based polymers can also be used. In addition, the polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain can be used, such as The resin composition which has an alternating copolymer which consists of isobutylene and N-methylmaleimide, and an acrylonitrile-styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion-molded product of the above-mentioned resin composition.

Surface treatments such as hard coating treatment, antireflection treatment, anti-sticking treatment, and anti-glare treatment may be applied to the protective layer 20 as necessary.

The thickness of the protective layer 20 is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and further preferably 5 μm to 150 μm. In addition, when the surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

When an inner protective layer is provided between the polarizer 10 and the first optical compensation layer 30 , the inner protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the retardation Rth(550) in the thickness direction is -10 nm to +10 nm. The inner protective layer may be composed of any appropriate material as long as it is optically isotropic. The material may be appropriately selected from, for example, the materials described above for the protective layer 20 .

The thickness of the inner protective layer is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and further preferably 15 μm to 95 μm.

A-5. Others

Each layer constituting the polarizing plate with an optical compensation layer is bonded via any appropriate pressure-sensitive adhesive layer or adhesive layer.

Although not shown, an adhesive layer may be provided on the second optical compensation layer 40 side of the polarizing plate 100 with an optical compensation layer. By providing a pressure-sensitive adhesive layer in advance, bonding with other optical members (for example, an organic EL panel) can be made easy. Moreover, it is preferable to stick a release film on the surface of this pressure-sensitive adhesive layer until it is ready for use. By temporarily sticking the release film, it is possible to protect the pressure-sensitive adhesive layer and form a roll.

B. Organic EL Panel

The organic EL panel of the present invention includes an organic EL unit and the polarizing plate with an optical compensation layer described in the above-mentioned item A, which is provided on the visual confirmation side of the organic EL unit. The polarizing plate with an optical compensation layer is laminated so that the second optical compensation layer is on the side of the organic EL unit (the polarizer is on the side of visual confirmation).

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, the measurement method of each characteristic is as follows.

(1) Thickness

The measurement was performed using a dial indicator (manufactured by PEACOCK, product name "DG-205", dial indicator stand (product name "pds-2")).

(2) Phase difference

A sample of 50 mm×50 mm was cut out from the retardation film constituting the optical compensation layer of each of the polarizers with optical compensation layers of Examples and Comparative Examples as measurement samples, and the measurement was performed using Axoscan manufactured by Axometrics. The measurement wavelengths were 450 nm and 550 nm, and the measurement temperature was 23°C.

In addition, the average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive indices nx, ny, and nz were calculated from the obtained retardation values.

(3) Front reflection brightness

The polarizers with the optical compensation layer obtained in the examples and the comparative examples were connected to the organic EL display device (LG Display, product name "55C7P") through the pressure-sensitive adhesive layer so that the optical compensation layer was on the organic EL side. The visual confirmation side of the organic EL panel was bonded to obtain an organic EL display device.

The organic EL was made to display a black image, and the front reflection luminance was measured using a spectrophotometer (product name "CM-2600D") manufactured by Konica Minolta.

(4) Reflection characteristics in oblique directions

Simulations were performed using the properties of the polarizers with optical compensation layers obtained in Examples and Comparative Examples. The oblique direction (polar angle of 60°) was evaluated. "LCD MASTER Ver.6.084" manufactured by Shintech Corporation was used for the simulation. A simulation of reflection characteristics was performed using the extended functions of LCD Master.

[Example 1]

(i) Fabrication of the first optical compensation layer

As the resin film, a commercially available cyclic olefin-based resin film (manufactured by JSR Corporation, product name "Arton (R5000)") was used. The thickness was 130 μm and the Tg was 137°C. A 60-μm-thick shrinkable film (manufactured by Toray Industries, Ltd., product name "TORAYFAN BO2873") was pasted on both sides of the film via an acrylic pressure-sensitive adhesive layer (thickness: 15 μm), and supplied to the free end unidirectional By stretching, a retardation film constituting the first optical compensation layer was obtained. The stretching temperature was set to 134° C., and the stretching ratio was set to 1.06 times. The obtained retardation film (ie, the first optical compensation layer) had Re(550) of 257 nm, Nz coefficient of 0.59, and Re(450)/Re(550) of 1.00.

(ii) Fabrication of the second optical compensation layer

A retardation film constituting the second optical compensation layer was produced in the same manner as (i) Production of the first optical compensation layer, except that the stretching temperature was set to 135° C. and the stretching magnification was set to 1.03 times. The obtained retardation film (ie, the second optical compensation layer) had Re(550) of 130 nm, Nz coefficient of 0.6, and Re(450)/Re(550) of 1.00.

(iii) Fabrication of polarizer

Simultaneously stretched a long roll of a polyvinyl alcohol (PVA)-based resin film (manufactured by Toray Industries, product name "PE3000") with a thickness of 30 μm to 5.9 times in the longitudinal direction by a roll stretching machine. Swelling, dyeing, cross-linking, washing treatment, and finally drying treatment were performed, thereby producing a polarizer having a thickness of 12 μm.

Specifically, as for the swelling treatment, it was stretched to 2.2 times while being treated with pure water at 20°C. Next, in terms of dyeing treatment, the obtained polarizer was placed in an aqueous solution at 30° C. in which the weight ratio of iodine and potassium iodide adjusted for the iodine concentration was 1:7 so that the obtained polarizer had a single transmittance of 45.0%. It was stretched to 1.4 times while being processed. Furthermore, two-stage cross-linking treatment was used for the cross-linking treatment, and the first-stage cross-linking treatment was stretched to 1.2 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 40°C. The boric acid content of the aqueous solution of the first-stage crosslinking treatment was set to 5.0% by weight, and the potassium iodide content was set to 3.0% by weight. The crosslinking treatment in the second stage was stretched to 1.6 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 65°C. The boric acid content of the aqueous solution of the second-stage crosslinking treatment was set to 4.3% by weight, and the potassium iodide content was set to 5.0% by weight. In addition, the washing process was performed in a potassium iodide aqueous solution at 20°C. The potassium iodide content of the washing-processed aqueous solution was set to 2.6% by weight. Finally, in terms of drying treatment, the polarizer was obtained by drying at 70° C. for 5 minutes.

(iv) Production of polarizer

A HC-coating layer (7 μm) having a hard coat (HC) layer (7 μm) formed on one side of a TAC film (25 μm) by a hard coating process was laminated on one side of the polarizer via a polyvinyl alcohol-based adhesive. TAC film (thickness: 32 μm, corresponding to the protective layer), a long polarizing plate having a protective layer/polarizer configuration was obtained.

(v) Fabrication of polarizer with optical compensation layer

The polarizing plate, the first optical compensation layer and the second optical compensation layer obtained above are cut into predetermined sizes, the polarizer surface of the polarizing plate and the first optical compensation layer are pasted through the acrylic adhesive, and the polarizer surface and the first optical compensation layer are further separated. The first optical compensation layer and the second optical compensation layer are bonded together with an acrylic adhesive. In this way, a polarizing plate with an optical compensation layer having a configuration of protective layer/polarizer/first optical compensation layer/second optical compensation layer was obtained. In addition, the cutting of the first optical compensation layer was performed so that the angle formed by the absorption axis of the polarizer and the slow axis of the first optical compensation layer in the polarizing plate with the optical compensation layer became 15°. In addition, the cutting of the second optical compensation layer was performed so that the angle formed by the absorption axis of the polarizer and the slow axis of the second optical compensation layer in the polarizing plate with the optical compensation layer became 75°. That is, the number of times of the step (RtoS) of cutting and bonding each layer constituting the polarizing plate with an optical compensation layer was two.

The obtained polarizing plate with an optical compensation layer was used for the evaluation of the above (3). Moreover, the simulation of the reflection characteristic of the said (4) was performed using the characteristic of the obtained polarizing plate with an optical compensation layer. The results are shown in Table 1.

[Example 2]

A first optical compensation layer and a second optical compensation layer were obtained in the same manner as in Example 1 except that the stretching temperature and stretching ratio described in Table 1 were used. Re(550) of the obtained first optical compensation layer was 317 nm, Nz coefficient was 0.75, and Re(450)/Re(550) was 1.00. Re(550) of the obtained second optical compensation layer was 136 nm, Nz coefficient was 0.41, and Re(450)/Re(550) was 1.00. The polarizing plate and the 1st optical compensation layer were bonded together by roll-to-roll, and the shrinkable film was peeled and removed, and the laminated body of the protective layer/polarizer/1st optical compensation layer was obtained. The absorption axis of the polarizer is substantially parallel to the slow axis of the first optical compensation layer. The laminate was cut into a predetermined size, and the second optical compensation layer was cut and bonded so that the angle formed by the absorption axis of the polarizer and the slow axis of the second optical compensation layer was 45°, thereby obtaining A polarizer with an optical compensation layer having the configuration of protective layer/polarizer/first optical compensation layer/second optical compensation layer. That is, the number of times of the process (RtoS) of cutting and bonding each layer which comprises the polarizing plate with an optical compensation layer is one. Furthermore, except having used this polarizing plate with an optical compensation layer, it carried out similarly to Example 1, and produced the organic electroluminescent panel. The obtained polarizing plate with an optical compensation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]

(i) Fabrication of the first optical compensation layer

(i-1) Production of polycarbonate resin film

Polymerization was performed using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux cooler controlled at 100°C. 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC) and magnesium acetate tetra The hydrate was charged in a molar ratio such that BHEPF/ISB/DEG/DPC/magnesium acetate=0.348/0.490/0.162/1.005/1.00×10 ⁻⁵ . The inside of the reactor was sufficiently substituted with nitrogen (oxygen concentration: 0.0005 to 0.001 vol %), then heated with a heat medium, and stirring was started when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature was brought to 220°C, and the pressure was started to be reduced while maintaining the temperature. After reaching 220°C, it was set to 13.3 kPa for 90 minutes. The phenol vapor by-produced with the polymerization reaction was introduced into a reflux cooler 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 introduced into a condenser at 45°C for recovery.

Nitrogen was introduced into the first reactor to temporarily return to atmospheric pressure, and then the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were started, and the internal temperature was set to 240° C. and the pressure to be 0.2 kPa for 50 minutes. Then, polymerization is performed until a predetermined stirring power is obtained. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the reaction liquid was drawn out in the form of strands, and pelletized with a rotary cutter to obtain BHEPF/ISB/DEG=34.8/49.0/16.2 [mol%] ] The copolymerization composition of polycarbonate resin. The reduced viscosity of this polycarbonate resin was 0.430 dL/g, and the glass transition temperature was 128°C.

(i-2) Production of the first optical compensation layer

The obtained polycarbonate resin was vacuum-dried at 80° C. for 5 hours, and then a single-screw extruder (manufactured by Isuzu Chemical Machinery Co., Ltd., screw diameter: 25 mm, cylinder set temperature: 220° C.), T A die (width: 900 mm, set temperature: 220° C.), a cooling roll (set temperature: 125° C.), and a film forming apparatus of a winder were used to obtain a polycarbonate resin film having a thickness of 130 μm. The water absorption of the obtained polycarbonate resin film was 1.2%.

The first optical compensation layer was obtained by diagonally stretching the polycarbonate resin film obtained as described above according to the method of Example 1 of JP-A No. 2014-194483. The Re(550) of the obtained first optical compensation layer was 139 nm, the Nz coefficient was 1.10, and the Re(450)/Re(550) was 0.89.

(ii) Fabrication of the second optical compensation layer

The side chain type liquid crystal polymer represented by the following chemical formula (II) (the numbers 65 and 35 in the formula represent the mol % of the monomer unit, and it is represented in the form of a block polymer for convenience; the weight average molecular weight is 5000) by weight. 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: product name: Paliocolor LC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Seika Co., Ltd.: product name: IRGACURE 907) were dissolved in In 200 parts by weight of cyclopentanone, a liquid crystal coating liquid was prepared. Then, the coating liquid was applied on a base film (norbornene-based resin film: manufactured by Japan ZEON Co., Ltd., product name "ZEONEX") by a wire bar coater, and then heated and dried at 80° C. for 4 minutes. , thereby aligning the liquid crystal. The liquid crystal layer was cured by irradiating the liquid crystal layer with ultraviolet rays, and a liquid crystal fixed layer (thickness: 0.58 μm) to be the second optical compensation layer was formed on the substrate. Re(550) of the obtained second optical compensation layer was 0 nm, and Rth(550) was -71.

Chemical formula 1

The first optical compensation layer and the second optical compensation layer obtained in the above (i) and (ii) were bonded to each other by roll-to-roll, and the base material was peeled off to obtain a protective layer/polarizer. A polarizer with an optical compensation layer consisting of the first optical compensation layer/the second optical compensation layer. The angle formed by the absorption axis of the polarizer and the slow axis of the first optical compensation layer was 45°. Further, an organic EL surface was produced in the same manner as in Example 1, except that this polarizing plate with an optical compensation layer was used. The obtained polarizing plate with an optical compensation layer and an organic EL panel were subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 2]

An optical compensation layer with a protective layer/polarizer/first optical compensation layer/second optical compensation layer was obtained in the same manner as in Comparative Example 1, except that the thickness of the second optical compensation layer was set to 0.44 μm polarizer. The Re(550) of the first optical compensation layer was 139 nm, the Nz coefficient was 1.00, and the Re(450)/Re(550) was 0.89. Re(550) of the second optical compensation layer was 0 nm, and Rth(550) was -54. Furthermore, except having used this polarizing plate with an optical compensation layer, it carried out similarly to Example 1, and produced the organic electroluminescent panel. The obtained polarizing plate with an optical compensation layer and an organic EL panel were subjected to the same evaluation as in Example 1. The results are shown in Table 1.

Table 1

*Indicates the retardation (Rth) in the thickness direction.

[Evaluation]

As can be seen from Table 1, the polarizing plate with an optical compensation layer according to the example of the present invention is excellent in the anti-reflection property in the oblique direction while maintaining the excellent anti-reflection property in the front direction. Furthermore, according to the Example, it was confirmed that the hue in the oblique direction can be set to neutral.

Industrial Availability

The polarizing plate with an optical compensation layer of the present invention can be applied to an organic EL panel.

Claims (3)

1. A polarizer with an optical compensation layer, which is used in an organic EL panel, and includes a polarizer, a first optical compensation layer and a second optical compensation layer in this order, Wherein, the first optical compensation layer shows the refractive index characteristic of nx>nz>ny, Re(550) is 220nm～300nm, Nz coefficient is 0.4～0.8, and the absorption axis direction of the polarizer is the same as that of the first optical compensation layer. The angle formed by the slow axis direction of the layer is 5° to 25°, The second optical compensation layer exhibits a refractive index characteristic of nx>nz>ny, Re(550) is 90nm-170nm, Nz coefficient is 0.4-0.8, and the absorption axis direction of the polarizer is the same as that of the second optical compensation layer. The angle formed by the slow axis direction is 65° to 85°, Re(450) and Re(550) of each of the first optical compensation layer and the second optical compensation layer are substantially equal, Here, Re(450) and Re(550) represent in-plane retardation measured with light having wavelengths of 450 nm and 550 nm at 23°C, respectively. 2. A polarizer with an optical compensation layer, which is used in an organic EL panel, and includes a polarizer, a first optical compensation layer and a second optical compensation layer in this order, Wherein, the first optical compensation layer shows the refractive index characteristic of nx>nz>ny, Re(550) is 280nm～360nm, Nz coefficient is 0.5～0.9, and the absorption axis direction of the polarizer is the same as that of the first optical compensation layer. The angles formed by the slow axis directions of the layers are substantially parallel, The second optical compensation layer exhibits a refractive index characteristic of nx>nz>ny, Re(550) is 100nm-180nm, Nz coefficient is 0.2-0.6, and the absorption axis direction of the polarizer is the same as that of the second optical compensation layer. The angle formed by the slow axis direction is 35° to 55°, Re(450) and Re(550) of each of the first optical compensation layer and the second optical compensation layer are substantially equal, Here, Re(450) and Re(550) represent in-plane retardation measured with light having wavelengths of 450 nm and 550 nm at 23°C, respectively. 3. An organic EL panel comprising the polarizing plate with an optical compensation layer according to claim 1 or 2.

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