WO2017038416A1

WO2017038416A1 - Longitudinally oriented optical compensation layer-equipped polarizing plate and organic el panel using same

Info

Publication number: WO2017038416A1
Application number: PCT/JP2016/073518
Authority: WO
Inventors: 敏行飯田
Original assignee: 日東電工株式会社
Priority date: 2015-08-31
Filing date: 2016-08-10
Publication date: 2017-03-09
Also published as: SG11201800797VA; JP6512998B2; CN107924012B; JP2017049362A; TWI801329B; TW201710721A; CN107924012A; KR102561199B1; KR20180039649A

Abstract

Provided is a longitudinally oriented optical compensation layer-equipped polarizing plate which exhibits an excellent reflective color phase and excellent viewing angle characteristics, and can be produced with extremely high production efficiency. The optical compensation layer-equipped polarizing plate is longitudinally oriented, and is to be used in an organic EL panel. The optical compensation layer-equipped polarizing plate is equipped with a longitudinally oriented polarizer, a longitudinally oriented first optical compensation layer, and a longitudinally oriented second optical compensation layer, in this order. The absorption axis direction of the polarizer is substantially perpendicular or parallel to the lengthwise direction. The first optical compensation layer exhibits refractive index properties which satisfy nx>ny≥nz, the Re(550) thereof is 100-180nm, the Nz coefficient thereof is 1.0-2.0, the relationship Re(450)<Re(550) is satisfied, and the angle formed between the lengthwise direction and the slow axis of the first optical compensation layer is 35-55°. The second optical compensation layer exhibits refractive index properties which satisfy nz>nx>ny, the Re(550) thereof is 5-20nm, the Rth(550) thereof is -200 to -20nm, and the slow axis direction of the second optical compensation layer is substantially perpendicular or parallel to the lengthwise direction.

Description

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

The present invention relates to a long polarizing plate with an optical compensation layer and an organic EL panel using the same.

In recent years, with the spread of thin displays, displays (organic EL display devices) equipped with organic EL panels have been proposed. Since the organic EL panel has a highly reflective metal layer, problems such as external light reflection and background reflection tend to occur. Thus, it is known to prevent these problems by providing a circularly polarizing plate on the viewing side. As a general circularly polarizing plate, a retardation film (typically a λ / 4 plate) is laminated so that its slow axis forms an angle of about 45 ° with respect to the absorption axis of the polarizer. Are known. In addition, in order to further improve the antireflection characteristics, attempts have been made to laminate retardation films (optical compensation layers) having various optical characteristics. On the other hand, from the viewpoint of production efficiency, a long (particularly roll-shaped) circularly polarizing plate that can be produced by so-called roll-to-roll is desired. However, in the production of a circularly polarizing plate by roll-to-roll, the optical film is displaced from the set direction of the optical axis by laminating, and the slow retardation of the long retardation film (for example, λ / 4 plate) is oblique. Many problems remain, such as difficulty in controlling the shaft and variations in characteristics in the width direction.

Japanese Patent No. 3325560

The present invention has been made to solve the above-described conventional problems, and its main purpose is to realize a long reflective shape and a viewing angle characteristic that can be obtained with extremely excellent manufacturing efficiency. Another object of the present invention is to provide a polarizing plate with an optical compensation layer.

The polarizing plate with an optical compensation layer of the present invention has a long shape and is used for an organic EL panel. The polarizing plate with an optical compensation layer includes a long polarizer, a long first optical compensation layer, and a long second optical compensation layer in this order. The absorption axis direction of the polarizer is substantially perpendicular or parallel to the longitudinal direction; the first optical compensation layer exhibits a refractive index characteristic of nx> ny ≧ nz, and Re (550) is 100 nm. 180 nm, Nz coefficient is 1.0 to 2.0, satisfies the relationship of Re (450) <Re (550), and an angle formed by the slow axis and the longitudinal direction of the first optical compensation layer The second optical compensation layer exhibits a refractive index characteristic of nz>nx> ny, Re (550) is 5 nm to 20 nm, and Rth (550) is −200 nm to −20 nm. And the slow axis direction of the second optical compensation layer is substantially perpendicular or parallel to the longitudinal direction. Here, Re (450) and Re (550) represent in-plane retardation measured with light having a wavelength of 450 nm and 550 nm at 23 ° C., respectively, and Rth (550) is measured with light having a wavelength of 550 nm at 23 ° C. Represents the retardation in the thickness direction.
In one embodiment, the polarizing plate with an optical compensation layer is wound in a roll shape.
In one embodiment, the first optical compensation layer is a retardation film obtained by oblique stretching.
In one embodiment, the polarizing plate with an optical compensation layer further includes a conductive layer and a base material in this order on the opposite side of the second optical compensation layer from the first optical compensation layer.
According to another aspect of the present invention, an organic EL panel is provided. This organic EL panel includes the above polarizing plate with an optical compensation layer cut into a predetermined size.

According to the present invention, a long polarizing plate with an optical compensation layer is optimized by combining the refractive index characteristics, in-plane retardation, thickness direction retardation, and slow axis direction of the two optical compensation layers. Thus, it is possible to obtain a polarizing plate with an optical compensation layer that can be produced by roll-to-roll production and that can realize excellent reflection hue and viewing angle characteristics.

It is a schematic sectional drawing of the polarizing plate with an optical compensation layer by one Embodiment of this invention.

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)
The 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 in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re (λ)” is an in-plane retardation measured with light having a wavelength of λ nm at 23 ° C. Re (λ) is determined by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). For example, “Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C.
(3) Thickness direction retardation (Rth)
“Rth (λ)” is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. Rth (λ) is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film). For example, “Rth (550)” is a retardation in the thickness direction measured with 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 between 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 between two directions is 0 ° ± 10 °, preferably 0 ° ± 7 °, more preferably 0 ° ± 5 °. Further, in the present specification, the term “orthogonal” or “parallel” may include a substantially orthogonal state or a substantially parallel state.

A. 1 is a schematic sectional view of a polarizing plate with an optical compensation layer according to one 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. Practically, the protective layer 20 can be provided on the opposite side of the polarizer 10 from the first optical compensation layer 30 as in the illustrated example. Preferably, the polarizing plate 100 with an optical compensation layer does not include an optically anisotropic layer between the polarizer 10 and the first optical compensation layer 30. The optically anisotropic layer refers to a layer having, for example, an in-plane retardation Re (550) exceeding 10 nm and / or a thickness direction retardation Rth (550) being less than −10 nm or exceeding 10 nm. Examples of the optically anisotropic layer include a liquid crystal layer, a retardation film, and a protective film. When the polarizing plate with an optical compensation layer does not include an optically anisotropic layer, in one embodiment, the first optical compensation layer 30 can function as a protective layer for the polarizer. In another embodiment, an optically isotropic protective layer (hereinafter referred to as an optically isotropic layer) is provided between the polarizer 10 and the first optical compensation layer 30 (that is, on the side opposite to the protective layer 20 of the polarizer 10). , Also referred to as an inner protective layer (not shown) may be provided. Further, if necessary, a conductive layer and a base material may be provided in this order on the opposite side of the second optical compensation layer 40 from the first optical compensation layer 30 (that is, outside the second optical compensation layer 40). Good (both not shown). The base material is closely adhered to the conductive layer. In the present specification, “adhesion lamination” means that two layers are directly and firmly laminated without an adhesive layer (for example, an adhesive layer or an adhesive layer). The conductive layer and the base material can be typically introduced into the polarizing plate 100 with an optical compensation layer as a laminate of the base material and the conductive layer. By further providing a conductive layer and a substrate, the polarizing plate 100 with an optical compensation layer can be suitably used for an inner touch panel type input display device.

Although not clear from the drawings, the polarizing plate with an optical compensation layer of the present embodiment is long. Therefore, the constituent elements of the polarizing plate with an optical compensation layer (for example, the polarizer, the first and second optical compensation layers, the protective layer, and the conductive layer and the substrate, if present) are also long. . In one embodiment, the polarizing plate with an optical compensation layer is wound in a roll shape. In this specification, “long shape” means an elongated shape having a sufficiently long length with respect to the width. For example, an elongated shape having a length that is 10 times or more, preferably 20 times or more the width. Including. Therefore, the polarizing plate 100 with an optical compensation layer is, for example, a long retardation film constituting the long polarizer 10 and the first optical compensation layer 30 and a long length constituting the second optical compensation layer 40. It can be prepared by laminating a long retardation film and a long protective film constituting a protective layer as needed, by roll-to-roll. In this specification, “roll-to-roll” means that the roll-shaped films are bonded together while aligning their longitudinal directions.

The absorption axis direction of the polarizer 10 is substantially orthogonal or parallel to the longitudinal direction. The first optical compensation layer 30 has a refractive index characteristic of nx> ny ≧ nz and has a slow axis. In the present embodiment, the first optical compensation layer 30 has a slow axis in an oblique direction with respect to the longitudinal direction. Specifically, the angle formed between the slow axis of the first optical compensation layer 30 and the longitudinal direction is 35 ° to 55 °, preferably 38 ° to 52 °, more preferably 42 ° to 48 °. And more preferably about 45 °. Since the absorption axis of the polarizer is expressed in the longitudinal direction or the width direction due to the manufacturing method thereof, the angle formed between the slow axis of the first optical compensation layer 30 and the longitudinal direction is the first optical compensation layer. This can correspond to an angle formed by 30 slow axes and the absorption axis of the polarizer 10. When the angle is within such a range, an excellent antireflection function can be realized. The first optical compensation layer 30 can typically be composed of a retardation film obtained by oblique stretching. The second optical compensation layer 40 has a refractive index characteristic of nz> nx> ny and has a slow axis. The slow axis direction of the second optical compensation layer 40 is substantially orthogonal or parallel to the longitudinal direction. Therefore, the slow axis of the second optical compensation layer 40 and the absorption axis of the polarizer 10 are substantially orthogonal or parallel, and the slow axis of the second optical compensation layer 40 and the first optical compensation layer are The angle formed by the 30 slow axes is 35 ° to 55 °, preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and even more preferably about 45 °. The second optical compensation layer having a refractive index characteristic of nz> nx> ny is provided in order to improve the viewing angle characteristic of the polarizing plate with an optical compensation layer, and is generally produced by stretching. , It has the advantage of being easy to form in a long shape. On the other hand, such a second optical compensation layer has an in-plane anisotropy, which may affect the antireflection characteristics of the polarizing plate with an optical compensation layer. In the long second optical compensation layer, the slow axis is substantially orthogonal or parallel to the longitudinal direction, and the relationship with the slow axis direction of the first optical compensation layer is optimized. In addition, by optimizing the in-plane retardation of the second optical compensation layer, the influence of in-plane anisotropy can be reduced. As described above, when the relationship with the slow axis direction of the first optical compensation layer is optimized so as to reduce the influence of anisotropy in the surface of the second optical compensation layer, the angle becomes about 45 °. . As a result, the angle formed by the slow axis of the first optical compensation layer and the absorption axis of the polarizer is 45 °, and the antireflection characteristics of the first optical compensation layer are very excellent. . As a result, it is possible to achieve both excellent viewing angle characteristics and antireflection characteristics (for example, reflection hue).

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

A-1. Polarizer Any appropriate polarizer may be adopted as the polarizer 10. 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 hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and ethylene / vinyl acetate copolymer partially saponified films. In addition, there may be mentioned polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because of excellent optical properties.

The dyeing with iodine is performed, for example, by immersing a PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing the PVA film in water and washing it before dyeing, not only can the surface of the PVA film be cleaned of dirt and anti-blocking agents, but the PVA film can be swollen to cause uneven staining. Can be prevented.

As a specific example of a polarizer obtained by using a laminate, a laminate of a resin substrate and a PVA resin layer (PVA resin film) laminated on the resin substrate, or a resin substrate and the resin Examples thereof include a polarizer obtained by using a laminate with a PVA resin layer applied and formed on a substrate. For example, a polarizer obtained by using a laminate of a resin base material and a PVA resin layer applied and formed on the resin base material may be obtained by, for example, applying a PVA resin solution to a resin base material and drying it. A PVA-based resin layer is formed thereon to obtain a laminate of a resin base material and a PVA-based resin layer; the laminate is stretched and dyed to make the PVA-based resin layer a polarizer; obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, the stretching may further include, if necessary, stretching the laminate in the air at a high temperature (for example, 95 ° C. or higher) before stretching in the aqueous boric acid solution. The obtained resin base material / polarizer laminate may be used as it is (that is, the resin base material may be used as a protective layer of the polarizer), and the resin base material is peeled from the resin base material / polarizer laminate. Any appropriate protective layer according to the purpose may be laminated on the release surface. Details of a method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. This publication is incorporated herein by reference in its entirety.

The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. As described above, the single transmittance of the polarizer is 43.0% to 46.0%, 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, the first optical compensation layer 30 has a refractive index characteristic of nx> ny ≧ nz. The in-plane retardation Re (550) of the first optical compensation layer is 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm. If the in-plane retardation of the first optical compensation layer is in such a range, the slow axis direction of the first optical compensation layer is set to 35 ° to 55 ° as described above with respect to the absorption axis direction of the polarizer. By setting the angle to be (especially about 45 °), an excellent antireflection function can be realized.

The first optical compensation layer exhibits the so-called reverse dispersion wavelength dependency. Specifically, the in-plane retardation satisfies the relationship Re (450) <Re (550). By satisfying such a relationship, an excellent reflection hue can be achieved. Re (450) / Re (550) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.

The Nz coefficient of the first optical compensation layer is 1.0 to 2.0, preferably 1.0 to 1.5, and more preferably 1.0 to 1.3. By satisfying such a relationship, a more excellent reflection hue can be achieved.

The variation of the in-plane retardation Re (550) in the width direction of the first optical compensation layer is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. The smaller the variation, the better. This is because problems caused by roll-to-roll bonding can be satisfactorily suppressed with respect to the antireflection characteristics of the obtained polarizing plate with an optical compensation layer. In this specification, “in-plane phase difference variation” refers to the maximum value of variation with respect to a set in-plane phase difference.

The variation in the slow axis direction in the width direction of the first optical compensation layer is preferably 5 ° or less, more preferably 3 ° or less, and further preferably 1 ° or less. The smaller the variation, the better. This is because, as in the case of variations in the in-plane retardation in the width direction, problems caused by roll-to-roll bonding can be satisfactorily suppressed with respect to the antireflection characteristics of the obtained polarizing plate with an optical compensation layer. The “variation in the slow axis direction” refers to the maximum value of the variation in the set slow axis direction.

The water absorption rate of the first optical compensation layer is preferably 3% or less, more preferably 2.5% or less, and further preferably 2% or less. By satisfying such a water absorption rate, it is possible to suppress changes in display characteristics over time. In addition, a water absorption rate can be calculated | required based on JISK7209.

The first optical compensation layer is typically a retardation film formed of any appropriate resin. As the resin for forming the retardation film, a polycarbonate resin is preferably used.

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 includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri, or polyethylene glycol, and an alkylene. A structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol or spiroglycol. Preferably, the polycarbonate resin is derived from a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or a di-, tri- or polyethylene glycol. More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. Details of the polycarbonate resin that can be suitably used in the present invention are described in, for example, Japanese Patent Application Laid-Open Nos. 2014-10291 and 2014-26266, and the description is incorporated herein by reference. The

The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 180 ° C. or lower, more preferably 120 ° C. or higher and 165 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, there is a possibility of causing a dimensional change after film formation, and the image quality of the resulting organic EL panel may be lowered. If the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K 7121 (1987).

The molecular weight of the polycarbonate resin can be represented by a reduced viscosity. The reduced viscosity is measured using a Ubbelohde viscometer at a temperature of 20.0 ° C. ± 0.1 ° C., using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL. The lower limit of the reduced viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, still more preferably 0.80 dL / g. If the reduced viscosity is less than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is larger than the upper limit, the fluidity at the time of molding is lowered, and there may be a problem that productivity and moldability are lowered.

The retardation film is typically produced by stretching a resin film in at least one direction.

Any appropriate method can be adopted as a method for forming the resin film. For example, a melt extrusion method (for example, a T-die molding method), a cast coating method (for example, a casting method), a calendar molding method, a hot press method, a co-extrusion method, a co-melting method, a multilayer extrusion method, an inflation molding method, etc. It is done. Preferably, a T-die molding method, a casting method, and an inflation molding method are used.

The thickness of the resin film (unstretched film) can be set to any appropriate value depending on desired optical characteristics, stretching conditions described later, and the like. The thickness is preferably 50 μm to 300 μm.

Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) may be employed for the stretching. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction can be used singly or simultaneously or sequentially. The stretching direction can also be performed in various directions and dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction. The stretching temperature is preferably Tg-30 ° C. to Tg + 60 ° C., more preferably Tg-10 ° C. to Tg + 50 ° C. with respect to the glass transition temperature (Tg) of the resin film.

A retardation film having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained by appropriately selecting the stretching method and stretching conditions.

In one embodiment, the retardation film is produced by continuously stretching a long resin film obliquely in the direction of an angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of θ with respect to the longitudinal direction of the film (slow axis in the direction of angle θ) can be obtained. For example, when laminating with a polarizer Roll-to-roll is possible, and the manufacturing process can be simplified. Since the absorption axis of the polarizer is expressed in the longitudinal direction or the width direction of the long film due to the production method, the angle θ is the absorption axis of the polarizer and the slow axis of the first optical compensation layer. It can be an angle between

Examples of the stretching machine used for the oblique stretching include a tenter type stretching machine capable of adding feed forces, pulling forces, or pulling forces at different speeds in the lateral and / or longitudinal directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as a long resin film can be continuously stretched obliquely.

The thickness of the retardation film (stretched film, that is, the first optical compensation layer) is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm, and further preferably 20 μm to 65 μm. With such a thickness, the desired in-plane retardation and thickness direction retardation can be obtained.

A-3. Second Optical Compensation Layer As described above, the second optical compensation layer 40 has a refractive index characteristic of nz>nx> ny. By providing the second optical compensation layer having such optical characteristics, the reflection hue when viewed from an oblique direction is remarkably improved, and as a result, the polarization with an optical compensation layer having very excellent viewing angle characteristics. A plate can be obtained.

The in-plane retardation Re (550) of the second optical compensation layer is 5 nm to 20 nm, preferably 5 nm to 15 nm, and more preferably 5 nm to 10 nm. If the in-plane phase difference is in such a range, there is an advantage that both excellent viewing angle characteristics and reflection hue can be achieved.

The thickness direction retardation Rth (550) of the second optical compensation layer is −200 nm to −20 nm, preferably −180 nm to −40 nm, more preferably −180 nm to −60 nm. If the retardation in the thickness direction is in such a range, there is an advantage that it is possible to achieve both excellent viewing angle characteristics and reflection hue as in the case of optimizing the in-plane retardation.

The second optical compensation layer can be formed of any appropriate material. Preferably, the second optical compensation layer may be composed of a retardation film formed of a fumaric acid diester resin described in JP 2012-32784 A. The thickness of the second optical compensation layer is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm.

A-4. Laminate The in-plane retardation Re (550) of the laminate of the first optical compensation layer and the second optical compensation layer is 120 nm to 160 nm, preferably 130 nm to 150 nm. The thickness direction retardation Rth (550) of the laminate is −40 nm to 100 nm, preferably −20 nm to 50 nm. By setting the optical characteristics of the laminate in this way, the reflection hue when viewed from an oblique direction is remarkably improved, and as a result, a polarizing plate with an optical compensation layer having a very excellent viewing angle characteristic is obtained. obtain.

A-5. 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 as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Further, a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

The protective layer 20 may be subjected to a surface treatment such as a hard coat treatment, an antireflection treatment, an antisticking treatment, and an antiglare treatment as necessary. Further / or, if necessary, the protective layer 20 may be treated to improve visibility when viewed through polarized sunglasses (typically, an (elliptical) circular polarization function is imparted, an ultrahigh phase difference is provided. May be applied). By performing such processing, excellent visibility can be achieved even when the display screen is viewed through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate with an optical compensation layer can be suitably applied to an image display device that can be used outdoors.

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 even more 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 as described above. In this specification, “optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say. The inner protective layer can be composed of any suitable material as long as it is optically isotropic. The material may be appropriately selected from the materials described above for the protective layer 20, for example.

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

A-6. Conductive layer or conductive layer with substrate The conductive layer can be formed on any suitable substrate by any suitable film formation method (eg, vacuum deposition, sputtering, CVD, ion plating, spraying, etc.). Further, it can be formed by forming a metal oxide film. After film formation, heat treatment (for example, 100 ° C. to 200 ° C.) may be performed as necessary. By performing the heat treatment, the amorphous film can be crystallized. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. The indium oxide may be doped with divalent metal ions or tetravalent metal ions. Indium composite oxides are preferable, and indium-tin composite oxide (ITO) is more preferable. Indium composite oxides are characterized by high transmittance (for example, 80% or more) in the visible light region (380 nm to 780 nm) and low surface resistance per unit area.

When the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The surface resistance value of the conductive layer is preferably 300Ω / □ or less, more preferably 150Ω / □ or less, and further preferably 100Ω / □ or less.

The conductive layer may be transferred from the base material to the second optical compensation layer, and the conductive layer alone may be used as a constituent layer of the polarizing plate with an optical compensation layer, or a laminate with the base material (conductive layer with base material). May be laminated on the second optical compensation layer. Typically, as described above, the conductive layer and the base material can be introduced into the polarizing plate with an optical compensation layer as a conductive layer with a base material.

Any suitable resin may be used as the material constituting the base material. Preferably, it is resin excellent in transparency. Specific examples include cyclic olefin resins, polycarbonate resins, cellulose resins, polyester resins, and acrylic resins.

Preferably, the substrate is optically isotropic. Therefore, the conductive layer can be used as a conductive layer with an isotropic substrate in a polarizing plate with an optical compensation layer. Examples of the material constituting the optically isotropic substrate (isotropic substrate) include, for example, a material having a main skeleton such as a norbornene-based resin or an olefin-based resin, a lactone ring, or glutar Examples thereof include materials having a cyclic structure such as an imide ring in the main chain of the acrylic resin. When such a material is used, when an isotropic substrate is formed, it is possible to suppress the expression of the phase difference accompanying the orientation of the molecular chain.

The thickness of the substrate is preferably 10 μm to 200 μm, more preferably 20 μm to 60 μm.

A-7. Others Arbitrary appropriate pressure-sensitive adhesive layers or adhesive layers are used for laminating the layers constituting the polarizing plate with an optical compensation layer of the present invention. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. The adhesive layer is typically formed of a polyvinyl alcohol-based adhesive.

Although not shown, an adhesive layer may be provided on the second optical compensation layer 40 side of the polarizing plate 100 with the optical compensation layer. By providing the pressure-sensitive adhesive layer in advance, it can be easily bonded to another optical member (for example, an organic EL cell). In addition, it is preferable that the peeling film is bonded together on the surface of this adhesive layer until it uses.

B. Manufacturing Method As a manufacturing method of the polarizing plate with an optical compensation layer, roll-to-roll can be typically employed. For example, the polarizing plate with an optical compensation layer includes a long resin film constituting the protective layer, a long polarizer having an absorption axis in the longitudinal direction, and a long shape constituting the first optical compensation layer. The phase difference film is laminated in such a manner that each of the phase difference films is transported in the longitudinal direction so that the respective longitudinal directions are aligned, and a laminated film is obtained. And a step of coating and forming on the surface of the optical compensation layer. The protective layer, the polarizer and the first optical compensation layer may be laminated at the same time, the protective layer and the polarizer may be laminated first, or the polarizer and the first optical compensation layer may be laminated first. May be. Alternatively, a laminated body of the first optical compensation layer and the second optical compensation layer may be formed first, and the laminated body may be used for the above-described lamination. Here, the angle between the absorption axis of the polarizer 10 and the slow axis of the first optical compensation layer 30 is 35 ° to 55 °, preferably 38 ° to 52 °, more preferably as described above. Is between 42 ° and 48 °, more preferably about 45 °.

In the present embodiment, as described above, the long retardation film constituting the first optical compensation layer has a slow axis in an oblique direction (for example, the direction of the angle θ) with respect to the longitudinal direction. . The angle θ may be an angle formed between the absorption axis of the polarizer as described above and the slow axis of the first optical compensation layer. Such a retardation film can be obtained by oblique stretching as described above. By using such a retardation film, roll-to-roll is possible in the production of a polarizing plate with an optical compensation layer, and the production process can be significantly shortened.

C. Organic EL Panel The long polarizing plate with an optical compensation layer described in the items A and B can be cut into a predetermined size and applied to an organic EL panel. Therefore, the present invention includes an organic EL panel using such a polarizing plate with an optical compensation layer. The organic EL panel of the present invention includes an organic EL cell and the polarizing plate with an optical compensation layer cut to a predetermined size on the viewing side of the organic EL cell. The polarizing plate with an optical compensation layer is laminated so that the second optical compensation layer is on the organic EL cell side (so that the polarizer is on the viewing side).

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 measuring method of each characteristic is as follows.

(1) Thickness The thickness was measured using a dial gauge (manufactured by PEACOCK, product name “DG-205”, dial gauge stand (product name “pds-2”)).
(2) Retardation A 50 mm × 50 mm sample was cut out from each optical compensation layer to obtain a measurement sample, and measurement was performed using Axoscan manufactured by Axometrics. The measurement wavelength was 450 nm, 550 nm, and the measurement temperature was 23 ° C.
Moreover, the average refractive index was measured using an Abbe refractometer manufactured by Atago Co., Ltd., and the refractive indexes nx, ny, and nz were calculated from the obtained retardation values.
(3) Variation in retardation value and slow axis direction Five samples of 50 mm × 50 mm were cut out at equal intervals in the width direction of the film roll constituting the first optical compensation layer. With respect to the cut sample, an in-plane retardation Re (550) and a slow axis were obtained using Axoscan manufactured by Axometrics. The maximum variation (%) with respect to the set phase difference was defined as the phase difference variation, and the maximum variation (°) with respect to the set slow axis direction was defined as the slow axis direction variation.
(4) Water Absorption Rate Measured according to “Test method for water absorption rate and boiling water absorption rate of plastics” described in JIS K 7209. The size of the test piece was a square with a side of 50 mm, and was obtained by immersing the test piece in water at a water temperature of 25 ° C. for 24 hours and then measuring the weight change before and after the immersion. The unit is%.
(5) Reflection hue and viewing angle characteristics A black image was displayed on the obtained organic EL panel, and the reflection hue was measured using a viewing angle measurement evaluation apparatus conoscope manufactured by Auoronic-MERCHERS. The “viewing angle characteristic” indicates the distance Δxy between two points between the reflected hue in the front direction and the reflected hue in the oblique direction (maximum value or minimum value at 45 ° polar angle) in the xy chromaticity diagram of the CIE color system. When this Δxy is smaller than 0.15, the viewing angle characteristics are evaluated as good.
(6) Front reflectance The black image was displayed on the obtained organic EL panel, and the front reflectance was measured using a spectrocolorimeter CM-2600d manufactured by Konica Minolta. When the reflectance is less than 20 (%), the reflection characteristics are evaluated as good.

[Example 1]
(Production of polycarbonate resin film)
Polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. 9,9- [4- (2-hydroxyethoxy) phenyl] fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate tetrahydrate in a molar ratio of BHEPF / ISB / DEG / DPC / magnesium acetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10 ⁻⁵ . After sufficiently replacing the inside of the reactor with nitrogen (oxygen concentration 0.0005 to 0.001 vol%), heating was performed with a heating medium, and stirring was started when the internal temperature reached 100 ° C. After 40 minutes from the start of temperature increase, the internal temperature was reached to 220 ° C., and control was performed so as to maintain this temperature. The phenol vapor produced as a by-product with the polymerization reaction was led to a reflux condenser at 100 ° C., and a monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the phenol vapor not condensed was led to a condenser at 45 ° C. and recovered.

Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Subsequently, the temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was obtained. When a predetermined power is reached, nitrogen is introduced into the reactor, the pressure is restored, the reaction solution is withdrawn in the form of a strand, pelletized with a rotary cutter, and BHEPF / ISB / DEG = 34.8 / 49.0 / A polycarbonate resin having a copolymer composition of 16.2 [mol%] was obtained. This polycarbonate resin had a reduced viscosity of 0.430 dL / g and a glass transition temperature of 128 ° C.

(Preparation 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 Industries, screw diameter 25 mm, cylinder set temperature: 220 ° C.), T-die (width 900 mm, set temperature: 220). ° C), a chill roll (set temperature: 125 ° C), and a film-forming apparatus equipped with a winder, a polycarbonate resin film having a thickness of 130 µm was produced. The polycarbonate resin film obtained had a water absorption rate of 1.2%.

The polycarbonate resin film obtained as described above was obliquely stretched by a method according to Example 1 of Japanese Patent Application Laid-Open No. 2014-194383 to obtain a retardation film.

The specific production procedure of the retardation film is as follows: A polycarbonate resin film (thickness 130 μm, width 765 mm) was preheated to 142 ° C. in the preheating zone of the stretching apparatus. In the preheating zone, the clip pitch of the left and right clips was 125 mm. Next, as soon as the film entered the first oblique stretching zone C1, the clip pitch of the right clip began to increase and increased from 125 mm to 177.5 mm in the first oblique stretching zone C1. The clip pitch change rate was 1.42. In the first oblique stretching zone C1, the clip pitch of the left clip started to decrease and decreased from 125 mm to 90 mm in the first oblique stretching zone C1. The clip pitch change rate was 0.72. Furthermore, as soon as the film entered the second oblique stretching zone C2, the clip pitch of the left clip started to increase and increased from 90 mm to 177.5 mm in the second oblique stretching zone C2. On the other hand, the clip pitch of the right clip was maintained at 177.5 mm in the second oblique stretching zone C2. Simultaneously with the oblique stretching, stretching in the width direction was performed 1.9 times. The oblique stretching was performed at 135 ° C. Next, MD shrinkage treatment was performed in the shrinkage zone. Specifically, the clip pitches of the left clip and right clip were both reduced from 177.5 mm to 165 mm. The shrinkage rate in the MD shrinkage treatment was 7.0%.

Thus, a retardation film (thickness 40 μm) was obtained. Re (550) of the obtained retardation film is 147 nm, Rth (550) is 167 nm (nx: 1.5977, ny: 1.59404, nz: 1.5935), and the refractive index is nx> ny = nz. The characteristics are shown. Moreover, Re (450) / Re (550) of the obtained retardation film was 0.89. The slow axis direction of the retardation film was 45 ° with respect to the longitudinal direction. The in-plane retardation Re (550) of the retardation film was 4 nm, the variation in retardation in the width direction was 20%, and the variation in the orientation angle in the width direction (the direction of the slow axis) was 2 °. .

(Preparation of second optical compensation layer)
In a 1 liter reactor equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 2.3 g of hydroxypropyl methylcellulose (trade name: Metroze 60SH-50, manufactured by Shin-Etsu Chemical Co., Ltd.), 600 g of distilled water, diisopropyl fumarate 358 g, diethyl fumarate 42 g (11.7 parts by weight with respect to 100 parts by weight of diisopropyl fumarate), methyl isobutyl ketone 10 g (2.4 parts by weight with respect to a total of 100 parts by weight of diisopropyl fumarate and diethyl fumarate) Then, 3.1 g of tert-butyl peroxypivalate as a polymerization initiator was added, nitrogen bubbling was performed for 1 hour, and suspension radical polymerization was performed by maintaining at 50 ° C. for 24 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents are recovered from the reactor, the polymer is filtered off, washed 5 times with 2000 g of distilled water, then washed 5 times with 2000 g of methanol, and vacuum dried at 80 ° C. for 6 hours. As a result, 310 g of a fumaric acid diester polymer was obtained.
The obtained fumaric acid diester was dissolved in MIBK, and the coating solution was coated on PET and dried at 80 ° C. for 5 minutes and further at 130 ° C. for 5 minutes to prepare a retardation layer (nz> nx = ny). Furthermore, a retardation layer having a refractive index characteristic of nz>nx> ny was formed by stretching, and this retardation layer was used as a second optical compensation layer.

(Production of laminate)
After the retardation layer (second optical compensation layer) is bonded to the retardation film (first optical compensation layer) by roll-to-roll through an acrylic adhesive, the base film is removed. Thus, a laminate in which the retardation layer (second optical compensation layer) was transferred to the retardation film was obtained.

(Production of polarizer)
At the same time, a long roll of polyvinyl alcohol (PVA) resin film (product name “PE3000”, manufactured by Kuraray Co., Ltd.) having a thickness of 30 μm is uniaxially stretched in the longitudinal direction so as to be 5.9 times in the longitudinal direction by a roll stretching machine. Swelling, dyeing, crosslinking, and washing treatment were performed, and finally a drying treatment was performed to produce a polarizer having a thickness of 12 μm.
Specifically, the swelling treatment was stretched 2.2 times while being treated with pure water at 20 ° C. Next, the dyeing treatment is performed in an aqueous solution at 30 ° C. in which the weight ratio of iodine and potassium iodide is 1: 7, the iodine concentration of which is adjusted so that the single transmittance of the obtained polarizer is 45.0%. The film was stretched 1.4 times. Furthermore, the crosslinking treatment employed a two-stage crosslinking treatment, and the first-stage crosslinking treatment was stretched 1.2 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 40 ° C. The boric acid content of the aqueous solution of the first-stage crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. The cross-linking treatment at the second stage was stretched 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 crosslinking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight. In addition, the cleaning treatment was performed with an aqueous potassium iodide solution at 20 ° C. The potassium iodide content of the aqueous solution for the washing treatment was 2.6% by weight. Finally, the drying process was performed at 70 ° C. for 5 minutes to obtain a polarizer.

(Preparation of polarizing plate)
An HC-TAC film (thickness: 32 μm, corresponding to a protective layer) having a hard coat (HC) layer formed on one side of the TAC film by a hard coat treatment on one side of the polarizer via a polyvinyl alcohol adhesive. ) Were bonded by roll-to-roll to obtain a long polarizing plate having a protective layer / polarizer configuration.

(Preparation of polarizing plate with optical compensation layer)
The polarizer surface of the polarizing plate obtained above and the first optical compensation layer surface of the first optical compensation layer / second optical compensation layer laminate obtained above through an acrylic adhesive Bonding was performed by roll-to-roll to obtain a long polarizing plate with an optical compensation layer having a configuration of protective layer / polarizer / first optical compensation layer / second optical compensation layer.

(Production of organic EL panel)
An adhesive layer was formed with an acrylic adhesive on the second optical compensation layer side of the obtained polarizing plate with an optical compensation layer, and cut into dimensions of 50 mm × 50 mm.
A smartphone (Galaxy-S5) manufactured by Samsung Radio Co., Ltd. was disassembled and the organic EL panel was taken out. The polarizing film affixed to this organic EL panel was peeled off, and the polarizing plate with an optical compensation layer cut out above was bonded together to obtain an organic EL panel.
The reflection characteristics of the obtained organic EL panel were measured by the procedure (5). As a result, it was confirmed that a neutral reflection hue was realized both in the front direction and in the oblique direction. Table 1 shows the results of viewing angle characteristics and front reflectance.

[Examples 2 to 5 and Comparative Examples 1 to 3]
A polarizing plate with an optical compensation layer and an organic EL panel having the configuration shown in Table 1 were prepared. The obtained polarizing plate with an optical compensation layer and the organic EL panel were subjected to the same evaluation as in Example 1. As shown in Table 1, the organic EL panels of Examples 2 to 5 were good in both viewing angle characteristics and front reflectance. Furthermore, about these organic electroluminescent panels, it confirmed that the neutral reflective hue was implement | achieved in both the front direction and the diagonal direction. On the other hand, the organic EL panels of Comparative Examples 1 to 3 had insufficient front reflectance and insufficient antireflection properties.

The polarizing plate with an optical compensation layer of the present invention is suitably used for an organic EL panel.

DESCRIPTION OF SYMBOLS 10 Polarizer 20 Protective layer 30 1st optical compensation layer 40 2nd optical compensation layer 100 Polarizing plate with an optical compensation layer

Claims

A long polarizer, a long first optical compensation layer, and a long second optical compensation layer are provided in this order,
The absorption axis direction of the polarizer is substantially perpendicular or parallel to the longitudinal direction;
The first optical compensation layer exhibits refractive index characteristics of nx> ny ≧ nz, Re (550) is 100 nm to 180 nm, Nz coefficient is 1.0 to 2.0, and Re (450) <Re ( 550), and the angle formed between the slow axis and the longitudinal direction of the first optical compensation layer is 35 ° to 55 °,
The second optical compensation layer exhibits a refractive index characteristic of nz>nx> ny, Re (550) is 5 nm to 20 nm, Rth (550) is −200 nm to −20 nm, and the second optical compensation layer The slow axis direction of the compensation layer is substantially perpendicular or parallel to the longitudinal direction;
Used for organic EL panels,
Long polarizing plate with optical compensation layer:
Here, Re (450) and Re (550) represent in-plane retardation measured with light having a wavelength of 450 nm and 550 nm at 23 ° C., respectively, and Rth (550) is measured with light having a wavelength of 550 nm at 23 ° C. Represents the retardation in the thickness direction.
The long polarizing plate with an optical compensation layer according to claim 1, which is wound in a roll shape.
The long polarizing plate with an optical compensation layer according to claim 1 or 2, which is a retardation film obtained by obliquely stretching the first optical compensation layer.
The long polarizing plate with an optical compensation layer according to any one of claims 1 to 3, further comprising a conductive layer and a base material in this order on the opposite side of the second optical compensation layer to the first optical compensation layer. Board.
An organic EL panel comprising the polarizing plate with an optical compensation layer according to claim 1, which is cut into a predetermined size.