JP7126479B2 - Polarizing plate with retardation layer and organic EL display device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polarizing plate with a retardation layer and an organic EL display device.

2. Description of the Related Art A display device is known in which a circularly polarizing plate is arranged on the viewing side of a display panel in order to improve poor visibility due to external light reflection or background reflection on the display screen of the display device. Patent Literatures 1 and 2 propose a polarizing plate that reduces the reflection of incident light from oblique directions in black display and achieves excellent oblique reflection hue, and a display device including the polarizing plate.

JP 2015-111236 A JP 2015-210459 A

However, the display devices using the polarizing plates described in Patent Documents 1 and 2 have a problem that unevenness occurs in reflected light and visibility is insufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress unevenness of reflected light and improve visibility. Another object of the present invention is to provide an organic EL display device.

The polarizing plate with a retardation layer of the present invention comprises a polarizer, a first retardation layer and a second retardation layer in this order, and the polarizer and the first retardation layer are connected via a first adhesive layer. and the first retardation layer and the second retardation layer are bonded via a second adhesive layer, and the thickness of the first retardation layer and the second retardation layer is 5 μm or less. , the average refractive index of the second adhesive layer is 1.55 or more, and the difference from the average refractive index of the first retardation layer and the difference from the average refractive index of the second retardation layer are less than 0.08.
In one embodiment, the difference in the average refractive index of the first adhesive layer from the average refractive index of the polarizer and the difference from the average refractive index of the first retardation layer is 0.06 or less. be.
In one embodiment, the thickness of the first adhesive layer and the second adhesive layer is 6 μm or less.
In one embodiment, each of the first retardation layer and the second retardation layer is an alignment fixed layer of a liquid crystal compound.
In one embodiment, the first retardation layer is a λ/2 plate and the second retardation layer is a λ/4 plate.
In one embodiment, the thickness of the polarizer is 12 μm or less.
In one embodiment, the thickness from the polarizer to the second retardation layer is 35 μm or less.
According to another aspect of the invention, an organic EL display device is provided. This organic EL display device includes the retardation layer-attached polarizing plate.

According to the present invention, it is possible to provide a retardation layer-equipped polarizing plate capable of suppressing unevenness of reflected light and improving visibility, and an organic EL display device including the retardation layer-equipped polarizing plate.

1 is a cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention; FIG.

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

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is an in-plane retardation measured at 23° C. with light having a wavelength of λ nm. 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 the in-plane retardation measured with light having a wavelength of 550 nm at 23°C.
(3) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of λ nm. For example, “Rth(550)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of 550 nm. Rth(λ) is determined by the formula: Rth=(nx−nz)×d, where d (nm) is the thickness of the layer (film).

A. 1. Polarizing Plate with Retardation Layer FIG. 1 is a cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The retardation layer-attached polarizing plate 10 includes a polarizer 1, a first retardation layer 2, and a second retardation layer 3 in this order.

Each of the first retardation layer 2 and the second retardation layer 3 has a thickness of 5 μm or less. The first retardation layer 2 typically functions as a λ/2 plate, and the second retardation layer 3 typically functions as a λ/4 plate. The first retardation layer 2 has a slow axis. In one embodiment, the angle between the slow axis of the first retardation layer 2 and the absorption axis of the polarizer 1 is, for example, 5° to 25°, preferably 10° to 20°, more preferably is between 10° and 17°, more preferably about 15°. The second retardation layer 3 also has a slow axis. The angle formed by the slow axis of the second retardation layer 3 and the absorption axis of the polarizer 1 is, for example, 60° to 90°, preferably 65° to 85°, more preferably 70° to 78°. and more preferably about 75°. The angle between the slow axis of the first retardation layer 2 and the slow axis of the second retardation layer 3 is, for example, 50° to 70°, preferably 52° to 65°, more preferably 55°. ° to 65°, more preferably about 60°.
In another embodiment, the angle between the slow axis of the first retardation layer 2 and the absorption axis of the polarizer 1 is, for example, -5° to -25°, preferably -10° to -20°. , more preferably -10° to -17°, more preferably about -15°. The second retardation layer 3 also has a slow axis. The angle formed by the slow axis of the second retardation layer 3 and the absorption axis of the polarizer 1 is, for example, -60° to -90°, preferably -65° to -85°, more preferably - 70° to -78°, more preferably about -75°. The angle between the slow axis of the first retardation layer 2 and the slow axis of the second retardation layer 3 is, for example, 50° to 70°, preferably 52° to 65°, more preferably 55°. ° to 65°, more preferably about 60°.
In yet another embodiment, the angle between the slow axis of the first retardation layer 2 and the absorption axis of the polarizer 1 is, for example, 60° to 90°, preferably 65° to 85°, and more It is preferably 70° to 78°, more preferably about 75°. The second retardation layer 3 also has a slow axis. The angle formed by the slow axis of the second retardation layer 3 and the absorption axis of the polarizer 1 is, for example, 5° to 25°, preferably 10° to 20°, more preferably 10° to 17°. and more preferably about 15°. The angle between the slow axis of the first retardation layer 2 and the slow axis of the second retardation layer 3 is, for example, 50° to 70°, preferably 52° to 65°, more preferably 55°. ° to 65°, more preferably about 60°.
In yet another embodiment, the angle between the slow axis of the first retardation layer 2 and the absorption axis of the polarizer 1 is, for example, -60° to -90°, preferably -65° to -85°. , more preferably -70° to -78°, and more preferably about -75°. The second retardation layer 3 also has a slow axis. The angle formed by the slow axis of the second retardation layer 3 and the absorption axis of the polarizer 1 is, for example, -5° to -25°, preferably -10° to -20°, more preferably - 10° to -17°, more preferably about -15°. The angle between the slow axis of the first retardation layer 2 and the slow axis of the second retardation layer 3 is, for example, 50° to 70°, preferably 52° to 65°, more preferably 55°. ° to 65°, more preferably about 60°.

The polarizer 1 and the first retardation layer 2 are bonded via the first adhesive layer 4, and the first retardation layer 2 and the second retardation layer 3 are bonded via the second adhesive layer 5. are glued together. The thicknesses of the first adhesive layer 4 and the second adhesive layer 5 are each typically 6 μm or less. The difference between the average refractive index of the first adhesive layer 4 and the average refractive index of the layers adjacent to the first adhesive layer 4 (the polarizer 1 and the first retardation layer 2) is typically 0.12. is less than The difference between the average refractive index of the first adhesive layer 4 and the average refractive index of the adjacent layers is preferably less than 0.10, more preferably less than 0.08, even more preferably 0.06. It is below. The average refractive index of the second adhesive layer 5 is 1.55 or more, and the average refractive index of the layers adjacent to the second adhesive layer 5 (first retardation layer 2 and second retardation layer 3) difference is less than 0.08. The difference between the average refractive index of the second adhesive layer 5 and the average refractive index of the adjacent layers is preferably 0.06 or less, more preferably 0.01 or less. By using the retardation layer-attached polarizing plate 10 in a display device, unevenness of reflected light in the display device can be suppressed and visibility can be improved. The retardation layer-attached polarizing plate 10 may have a protective film (not shown) on the side of the polarizer 1 opposite to the first retardation layer 2 .

The thickness of the retardation layer-attached polarizing plate 10 (total thickness of polarizer 1/first adhesive layer 4/first retardation layer 2/second adhesive layer 5/second retardation layer 3) is preferably 4 μm. ~35 μm, more preferably 6 μm to 20 μm.

B. Polarizer Any appropriate polarizer can be employed as the polarizer 1 . 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 the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films. In addition, oriented polyene films such as those dyed with dichroic substances such as iodine and dichroic dyes and stretched, and dehydrated PVA and dehydrochlorinated polyvinyl chloride films. A polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is preferably used because of its excellent optical properties.

The dyeing with iodine is performed by, for example, immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial drawing is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. If necessary, the PVA-based film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but also the PVA-based film can be swollen to remove uneven dyeing. can be prevented.

Specific examples of the polarizer obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and the resin A polarizer obtained by using a laminate with a PVA-based resin layer formed by coating on a substrate can be mentioned. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate. Then, any appropriate protective layer may be laminated on the release surface according to the purpose. Details of a method for manufacturing such a polarizer are described, for example, in Japanese Patent Application Laid-Open No. 2012-73580. The publication is incorporated herein by reference in its entirety.

The thickness of the polarizer 1 is preferably 12 μm or less, more preferably 1 μm to 10 μm, even more preferably 3 μm to 8 μm, particularly preferably 3 μm to 5 μm. If the thickness of the polarizer 1 is within such a range, the thickness of the entire polarizing plate 10 with a retardation layer can be reduced. By using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material, the thin polarizer 1 as described above can be produced.

The polarizer 1 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%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, still more preferably 99.9% or higher.

The average refractive index of the polarizer 1 is preferably 1.48-1.65, typically 1.55. If the average refractive index of the polarizer 1 is within the above range, it is easy to adjust the difference from the average refractive index of the first adhesive layer 4 .

C. First Retardation Layer and Second Retardation Layer As described above, in one embodiment of the present invention, the first retardation layer 2 can function as a λ/2 plate, and the second retardation layer 3 can function as a λ/4 plate. It can act as a plate. By the first retardation layer 2 functioning as a λ / 2 plate, the wavelength dispersion characteristics after lamination with the second retardation layer 3 functioning as a λ / 4 plate (in particular, the wavelength where the phase difference is outside λ / 4 range), the phase difference can be adjusted appropriately, and the circular polarization function can be exhibited in a wide wavelength range.

The in-plane retardation Re(550) of the first retardation layer 2 is 180 nm to 320 nm, preferably 200 nm to 300 nm, more preferably 200 nm to 280 nm. The first retardation layer 2 typically has a refractive index ellipsoid of nx>ny=nz or nz=nx>ny. The in-plane retardation Re(550) of the second retardation layer 3 is 80 nm to 180 nm, preferably 90 nm to 170 nm, more preferably 100 nm to 150 nm. The second retardation layer 3 typically has a refractive index ellipsoid of nx>ny=nz or nz=nx>ny.

The average refractive index of the first retardation layer 2 is preferably 1.50 to 1.70, typically 1.59 or 1.60. If the average refractive index of the first retardation layer 2 is within the above range, the difference from the average refractive index of the first adhesive layer 4 and / or the second adhesive layer 5 is less than 0.12 (further 0.06 or less). The thickness of the first retardation layer 2 is preferably 1 μm to 5 μm, more preferably 1 μm to 3 μm, particularly preferably 2 μm.

The average refractive index of the second retardation layer 3 is preferably 1.50 to 1.70, typically 1.59 or 1.60. If the average refractive index of the second retardation layer 3 is within the above range, the difference from the average refractive index of the second adhesive layer 5 can be less than 0.08. The thickness of the second retardation layer 3 is preferably 1 μm to 5 μm, more preferably 1 μm to 3 μm, particularly preferably 1 μm.

In one embodiment, the first retardation layer 2 and/or the second retardation layer 3 may be an alignment fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the obtained first retardation layer 2 and/or the second retardation layer 3 can be significantly increased compared to a non-liquid crystal material. The thickness of the first retardation layer and/or the second retardation layer for obtaining the internal retardation can be remarkably reduced. As a result, it is possible to realize further thinning of the retardation layer-attached polarizing plate 10 (ultimately, the organic EL display device). As used herein, the term "fixed alignment layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction and the alignment state is fixed.

In one embodiment, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first retardation layer 2 (second retardation layer 3) (homogeneous alignment). Examples of liquid crystal compounds include liquid crystal compounds whose liquid crystal phase is a nematic phase (nematic liquid crystal). As the liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. Either lyotropic or thermotropic mechanism may be used to develop the liquid crystallinity of the liquid crystal compound. The liquid crystal polymer and liquid crystal monomer may be used alone or in combination. Any appropriate liquid crystal monomer can be employed as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) available from BASF, E7 (trade name) available from Merck, and LC-Sillicon-CC3767 (trade name) available from Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable. Specific examples of the liquid crystal compound and details of the method for forming the alignment fixed layer are described in JP-A-2006-163343. The description of the publication is incorporated herein by reference.

In another embodiment, typically, the discotic liquid crystal compound is oriented in any one of vertical orientation, hybrid orientation and tilted orientation. Examples of liquid crystal compounds include discotic liquid crystal compounds. The discotic liquid crystalline compound typically has a discotic plane oriented substantially perpendicular to the film plane of the first retardation layer (second retardation layer). The fact that the discotic liquid crystalline compound is substantially perpendicular means that the average angle formed by the film plane and the disk plane of the discotic liquid crystalline compound is in the range of 70° to 90°. 80° to 90° is more preferred, and 85° to 90° is even more preferred. As the discotic liquid crystalline compound, for example, those described in JP-A-2007-108732 and JP-A-2010-244038 can be preferably used, but the compounds are not limited thereto.

D. First Adhesive Layer As described above, the average refractive index of the first adhesive layer 4 differs from the average refractive index of the layers adjacent to the first adhesive layer 4 by less than 0.12. When a thin retardation layer-attached polarizing plate having a thin retardation layer (e.g., 5 μm or less) is used in a display device, the thickness of each layer becomes uneven due to the difference in refractive index between the layers constituting the retardation layer-attached polarizing plate. , unevenness, etc. can be visually recognized as interference unevenness. On the other hand, since the difference between the average refractive index of the first adhesive layer 4 and the average refractive index of the layer adjacent to the first adhesive layer 4 is less than 0.12, the above interference unevenness is suppressed. and, as a result, visibility can be improved.

The average refractive index of the first adhesive layer 4 is preferably 1.52-1.64, more preferably 1.55-1.64. The thickness of the first adhesive layer 4 is preferably 10 nm to 6 μm, more preferably 200 nm to 2 μm.

The adhesive that can constitute the first adhesive layer 4 preferably has transparency and optical isotropy. As the adhesive, an active energy ray-curable adhesive can be typically used. The active energy ray-curable adhesive can be selected from radical-curing, cationic-curing, and anion-curing adhesives as needed. For example, a radical-curing and cationic-curing hybrid can be used in combination as appropriate. is also possible. Radical curing adhesives include, for example, adhesives containing, as curing components, compounds (eg, monomers and/or oligomers) having radically polymerizable groups such as (meth)acrylate groups and (meth)acrylamide groups. be done. In addition, "(meth)acryl" refers to acryl and/or methacryl.

As the active energy ray-curable adhesive, desired properties (for example, refractive index after curing) can be obtained by adjusting the type, combination, and blending ratio of double bond-containing monomers and/or oligomers, cross-linking agents, etc. It is possible to obtain an active energy ray-curable adhesive having Examples of components capable of adjusting the refractive index after curing include compounds having aromatic rings, compounds having halogen atoms, compounds having sulfur atoms, and inorganic particles such as titania and zirconia. Compounds having an aromatic ring include compounds having a naphthalene skeleton, a phenoxybenzyl skeleton, a fluorene skeleton, and a 9-vinylcarbazole skeleton. It may also contain a (meth)acryloyl group-containing compound as a diluent component, an acrylic oligomer as a plasticizer, and a radical photopolymerization initiator as a photopolymerization initiator.

E. Second Adhesive Layer The second adhesive layer 5 may consist of any suitable adhesive. As described above, the average refractive index of the second adhesive layer 5 differs from the average refractive index of the layers adjacent to the second adhesive layer 5 by less than 0.08. As a result, the above interference unevenness can be suppressed, and as a result, the visibility can be improved.

The average refractive index of the second adhesive layer 5 is 1.55 or more, preferably 1.55 to 1.64, more preferably 1.55 to 1.63. The thickness of the second adhesive layer 5 is preferably 10 nm to 6 μm, more preferably 200 nm to 2 μm. The adhesive that can constitute the second adhesive layer 5 is the same as the adhesive described for the first adhesive layer 4 in section D.

F. Protective Film The protective film is formed of any suitable film that can be used as a protective film for the polarizer 1 . Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based resins. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, 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 nitrile group in a side chain. can be used, for example, a resin composition comprising an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile/styrene copolymer. The polymer film can be, for example, an extrudate of the resin composition.

The (meth)acrylic resin has a Tg (glass transition temperature) of preferably 115° C. or higher, more preferably 120° C. or higher, still more preferably 125° C. or higher, and particularly preferably 130° C. or higher. It is because durability can be excellent. Although the upper limit of Tg of the (meth)acrylic resin is not particularly limited, it is preferably 170° C. or less from the viewpoint of moldability and the like.

As the (meth)acrylic resin, any appropriate (meth)acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly(meth)acrylic acid ester such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester - (meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer , methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferable examples include poly(meth)acrylic acid C1-6 alkyl such as polymethyl(meth)acrylate. Methyl methacrylate-based resins containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) are more preferred.

Specific examples of the (meth)acrylic resin include, for example, ACRYPET VH and ACRYPET VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and (meth)acrylic resins having a ring structure in the molecule described in JP-A-2004-70296. Resins, and high Tg (meth)acrylic resins obtained by intramolecular cross-linking or intramolecular cyclization reaction can be mentioned.

As the (meth)acrylic resin, a (meth)acrylic resin having a lactone ring structure is particularly preferable because it has high heat resistance, high transparency, and high mechanical strength. As the (meth)acrylic resin having the lactone ring structure, JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, JP-A-2005 Examples thereof include (meth)acrylic resins having a lactone ring structure, such as those described in JP-A-146084.

The (meth)acrylic resin having the lactone ring structure has a mass average molecular weight (also referred to as weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, especially It is preferably 50,000 to 500,000.

The (meth)acrylic resin having a lactone ring structure has a Tg (glass transition temperature) of preferably 115°C or higher, more preferably 125°C or higher, still more preferably 130°C or higher, particularly preferably 135°C, and most preferably 135°C. is above 140°C. It is because durability can be excellent. Although the upper limit of the Tg of the (meth)acrylic resin having the lactone ring structure is not particularly limited, it is preferably 170° C. or less from the viewpoint of moldability and the like. In this specification, "(meth)acrylic" refers to acrylic and/or methacrylic.

The retardation layer-attached polarizing plate 10 of the present invention is typically arranged on the viewing side of the image display device, and the protective film is typically arranged on the viewing side. Therefore, the protective film may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary.

Any appropriate thickness can be adopted as the thickness of the protective film as long as the effects of the present invention can be obtained. The thickness of the protective film is, for example, 10 μm to 100 μm, preferably 12 μm to 90 μm. In addition, when the surface treatment is given, the thickness of the protective film is the thickness including the thickness of the surface treatment layer.

G. Display Device The polarizing plate with a retardation layer described in the above items A to F can be applied to a display device such as a liquid crystal display device and an organic EL display device. Therefore, the present invention includes a display device using the retardation layer-attached polarizing plate. A display device according to an embodiment of the present invention includes a display element and the polarizing plate with a retardation layer according to any one of the above items A to F arranged on the viewing side of the display element. The retardation layer-attached polarizing plate is arranged so that the second retardation layer 3 faces the display element side.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. In addition, the measuring method of each characteristic is as follows.
1. Refractive index measurement of polarizer Using a prism coupler SPA-4000 (manufactured by Cylon Technology), the refractive index in the direction perpendicular to the absorption axis, the refractive index in the direction of the absorption axis, and the thickness of the in-plane refractive index of the polarizer The refractive index in the vertical direction was measured, and the average value of these was taken as the average refractive index of the polarizer. The measurement temperature was 23° C. and the measurement wavelength was 532 nm.
2. Refractive index measurement of retardation layer Using a prism coupler SPA-4000 (manufactured by Cylon Technology), out of the in-plane refractive indices of the retardation film, the refractive index in the direction perpendicular to the slow axis and the refraction in the slow axis direction and the refractive index in the thickness direction were measured, and the average value of these was taken as the average refractive index of the retardation layer. The measurement temperature was 23° C. and the measurement wavelength was 532 nm.
3. Refractive index measurement of adhesive layer Using a prism coupler SPA-4000 (manufactured by Cylon Technology), the in-plane refractive index and the thickness direction refractive index of the cured adhesive constituting the adhesive layer were measured, respectively. These average values were taken as the average refractive index of the adhesive layer. The measurement temperature was 23° C. and the measurement wavelength was 532 nm.
4. Retardation Measurement of Retardation Layer Measured using Axoscan (manufactured by Axometrics). The measurement temperature was 23° C. and the measurement wavelength was 550 nm.

(Production of polarizer)
An amorphous polyethylene terephthalate (A-PET) film (manufactured by Mitsubishi Plastics, Inc., trade name “Novaclear”, thickness: 100 μm) was used as the resin substrate. An aqueous solution of polyvinyl alcohol (PVA) resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosenol (registered trademark) NH-26”) is applied to one side of the resin substrate at 60 ° C. and dried to form a PVA with a thickness of 7 μm. A system resin layer was formed. The laminate thus obtained was immersed for 30 seconds in an insolubilizing bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. ( insolubilization step). Then, it was immersed for 60 seconds in a dyeing bath (iodine aqueous solution obtained by blending 0.2 parts by weight of iodine and 2 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. (dyeing process). Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 30°C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking step). After that, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 60° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). In the meantime, uniaxial stretching was performed in the machine direction (longitudinal direction) between rolls with different peripheral speeds (step B). The immersion time in the boric acid aqueous solution was 120 seconds, and the laminate was stretched until just before it broke. Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 parts by weight of water), and then dried with hot air at 60°C (washing/drying process ). Thus, a laminate was obtained in which a polarizer having a thickness of 5 μm was formed on the resin substrate. Next, the resin substrate is peeled off from the polarizer, and an acrylic transparent protective film described in JP-A-2012-3269 is attached as a protective film to one surface of the polarizer, thereby obtaining a polarizer with a protective film. Obtained. The protective film-attached polarizer was used after being subjected to corona treatment.

(Preparation of Retardation Film Constituting Retardation Layer)
(Retardation film A)
A coating liquid containing a rod-shaped polymerizable nematic liquid crystal monomer is applied to a transparent resin base material for λ/2 alignment which has been subjected to a rubbing treatment for an alignment film, and solidified while maintaining refractive index anisotropy to obtain a transparent resin substrate. A retardation film A having a thickness of 2 μm was produced on a resin substrate. Among the in-plane refractive indices of the retardation film A, the refractive index in the fast axis direction is 1.55, the refractive index in the slow axis direction is 1.68, and the refractive index in the thickness direction is 1.55. The refractive index was 1.59. The in-plane retardation Re(550) of the retardation film A was 260 nm. The obtained retardation film was subjected to corona treatment and used.
(Retardation film B)
A coating liquid containing a rod-shaped polymerizable nematic liquid crystal monomer is applied to a transparent resin base material for λ/4 alignment on which an alignment film has been subjected to rubbing treatment. A retardation film A having a thickness of 1 μm was produced on a resin substrate. Among the in-plane refractive indices of the retardation film B, the refractive index in the fast axis direction is 1.55, the refractive index in the slow axis direction is 1.68, and the refractive index in the thickness direction is 1.55. The refractive index was 1.59. The in-plane retardation Re(550) of the retardation film B was 120 nm. The obtained retardation film was subjected to corona treatment and used.
(Retardation film C)
A transparent resin substrate made of cellulose acylate was subjected to alkali saponification treatment, and then, an orientation film coating liquid was applied to the surface of the alkali saponification treated cellulose acylate, followed by drying to effect λ/2 orientation treatment. Next, a coating liquid containing a discotic liquid crystalline compound was applied to the alignment-treated surface of the transparent support, and the liquid crystal compound was heated and irradiated with UV to fix the alignment of the liquid crystal compound. A retardation film C was produced. Among the in-plane refractive indices of the retardation film C, the refractive index in the fast axis direction is 1.53, the refractive index in the slow axis direction is 1.64, and the refractive index in the thickness direction is 1.64. The refractive index was 1.60. The in-plane retardation Re(550) of the retardation film C was 246 nm. The obtained retardation film was subjected to corona treatment and used.
(Retardation film D)
A transparent resin substrate made of cellulose acylate was subjected to alkali saponification treatment, and then, the surface of the alkali saponification treatment of cellulose acylate was coated with an alignment film coating solution and dried to carry out λ/4 orientation treatment. Next, a coating liquid containing a discotic liquid crystalline compound is applied to the orientation-treated surface of the transparent support, and the orientation of the liquid crystal compound is fixed by heating and UV irradiation, thereby forming a 1-μm-thick layer on the transparent resin substrate. A retardation film D was produced. Of the in-plane refractive indices of the retardation film D, the refractive index in the fast axis direction is 1.53, the refractive index in the slow axis direction is 1.64, and the refractive index in the thickness direction is 1.64. The refractive index was 1.60. The in-plane retardation Re (550) of the retardation film D was 123 nm. The obtained retardation film was subjected to corona treatment and used.

(Preparation of Adhesive Constituting Adhesive Layer)
(Adhesive A)
Plaxel FA1DDM (manufactured by Daicel) 50 parts, acryloylmorpholine (ACMO: registered trademark) (manufactured by Kojin Co., Ltd.) 40 parts, ARFON UP-1190 (manufactured by Toagosei Co., Ltd.) 10 parts, photopolymerization initiator (product name "KAYACURE DETX -S", manufactured by Nippon Kayaku Co., Ltd.) and 3 parts of IRGACURE907 (manufactured by BASF Japan Co., Ltd.) were mixed to prepare an adhesive A. The in-plane refractive index of the cured product obtained by photocuring (300 mJ/cm ² ) the obtained adhesive A is 1.52, the refractive index in the thickness direction is 1.52, and the average refractive index is 1. 0.52.
(Adhesive B)
Light acrylate POB-A (manufactured by Kyoeisha Chemical) 40 parts, PLAXEL FA1DDM (manufactured by Daicel) 10 parts, acryloylmorpholine (ACMO: registered trademark) (manufactured by Kojin Co., Ltd.) 40 parts, ARFON UP-1190 (manufactured by Toagosei Co., Ltd.) Adhesive B was prepared by mixing 10 parts, 3 parts of a photopolymerization initiator (product name “KAYACURE DETX-S”, manufactured by Nippon Kayaku Co., Ltd.), and 3 parts of IRGACURE 907 (manufactured by BASF Japan). The in-plane refractive index of the cured product obtained by photocuring the obtained adhesive B (300 mJ/cm ² ) is 1.55, the refractive index in the thickness direction is 1.55, and the average refractive index is 1. 0.55.
(Adhesive C)
Ogsol EA-F5710 (manufactured by Osaka Gas Chemicals Co., Ltd.) 70 parts, Praxel FA1DDM (manufactured by Daicel) 10 parts, acryloylmorpholine (ACMO: registered trademark) (manufactured by Kojin Co., Ltd.) 18 parts, ARFON UP-1190 (manufactured by Toagosei Co., Ltd.) ) and 3 parts of a photopolymerization initiator (product name “DAROCUR1173” manufactured by BASF Japan) were mixed to prepare an adhesive C. The in-plane refractive index of the cured product obtained by photocuring (300 mJ/cm ² ) the obtained adhesive C is 1.60, the refractive index in the thickness direction is 1.60, and the average refractive index is 1. .60.
(Adhesive D)
9-vinylcarbazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 35 parts, Ogsol EA-F5710 (manufactured by Osaka Gas Chemicals Co., Ltd.) 40 parts, acryloylmorpholine (ACMO: registered trademark) 20 parts, ARFON UP-1190 (manufactured by Toagosei Co., Ltd.) 5 parts, Adhesive D was prepared by mixing 3 parts of a photopolymerization initiator (product name “DAROCUR1173”, manufactured by BASF Japan). The in-plane refractive index of the cured product obtained by photocuring the obtained adhesive D (300 mJ/cm ² ) is 1.64, the refractive index in the thickness direction is 1.64, and the average refractive index is 1. .64.

<Example 1>
The adhesive A constituting the first adhesive layer is applied to the polarizer, and the retardation film A constituting the first retardation layer is applied to the coated surface of the adhesive A so that the absorption axis of the polarizer and the retardation film A It was transferred from the transparent resin substrate so that the angle formed by the slow axis was 15°, and the adhesive A was cured by UV irradiation (300 mJ/cm ² ). Next, the adhesive B constituting the second adhesive layer is applied to the surface of the retardation film A opposite to the polarizer, and the retardation film D constituting the second retardation layer is applied to the adhesive B coated surface. , the angle formed by the absorption axis of the polarizer and the slow axis of the retardation film D is 75 °, and the angle formed by the slow axis of the retardation film A and the slow axis of the retardation film D is 60 ° A polarizing plate with a retardation layer was obtained by transferring from the transparent resin base material so as to obtain a polarizing plate with a retardation layer and curing the adhesive B by UV irradiation (300 mJ/cm ² ). The thickness of the cured adhesive A (first adhesive layer) was 1 μm, and the thickness of the cured adhesive B (second adhesive layer) was 1 μm.

<Example 2>
A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that the adhesive B was used as the adhesive constituting the first adhesive layer.

<Example 3>
A polarizing plate with a retardation layer was produced in the same manner as in Example 2 except that the adhesive C was used as the adhesive constituting the second adhesive layer.

<Example 4>
A polarizing plate with a retardation layer in the same manner as in Example 1 except that adhesive C was used as the adhesive constituting the first adhesive layer and adhesive D was used as the adhesive constituting the second adhesive layer. was made.

<Example 5>
The adhesive B constituting the first adhesive layer is applied to the polarizer, and the retardation film C constituting the first retardation layer is applied to the adhesive B coating surface, and the absorption axis of the polarizer and the retardation film C It was transferred from the transparent resin substrate so that the angle formed by the slow axis was 75°, and the adhesive B was cured by UV irradiation (300 mJ/cm ² ). Next, the adhesive B constituting the second adhesive layer is applied to the surface of the retardation film C opposite to the polarizer, and the retardation film B constituting the second retardation layer is applied to the adhesive B coated surface. , the angle formed by the absorption axis of the polarizer and the slow axis of the retardation film B is 15 °, and the angle formed by the slow axis of the retardation film C and the slow axis of the retardation film B is 60 ° A polarizing plate with a retardation layer was obtained by transferring from the transparent resin base material so as to obtain a polarizing plate with a retardation layer and curing the adhesive B by UV irradiation (300 mJ/cm ² ). The thickness of the cured adhesive B (first adhesive layer) was 1 μm, and the thickness of the cured adhesive B (second adhesive layer) was 1 μm.

<Example 6>
Retardation film C was used as the retardation film constituting the first retardation layer, and retardation film D was used as the retardation film constituting the second retardation layer in the same manner as in Example 2. A layered polarizing plate was produced.

<Example 7>
A polarizing plate with a retardation layer was produced in the same manner as in Example 2 except that the retardation film B was used as the retardation film constituting the second retardation layer.

<Comparative Example 1>
A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except that the adhesive A was used as the adhesive constituting the second adhesive layer.

<Comparative Example 2>
A polarizing plate was produced in the same manner as in Comparative Example 1, except that the adhesive B was used as the adhesive constituting the first adhesive layer.

(evaluation)
The retardation layer-attached polarizing plate of each example and comparative example was attached to a reflector via an acrylic pressure-sensitive adhesive, and the appearance was visually observed under a three-wavelength tube. Table 1 shows the results of evaluation according to the following criteria.
No unevenness was visible...◎
Almost no unevenness was visible (no problem in actual use)...○
Irregularities were visible...×

The retardation layer-attached polarizing plate of the present invention is suitably used for, for example, an image display device. Specifically, liquid crystal panels for liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copiers, printers, facsimiles, clocks, microwave ovens, etc., and antireflection plates for organic EL devices. etc. is suitably used.

REFERENCE SIGNS LIST 1 polarizer 2 first retardation layer 3 second retardation layer 4 first adhesive layer 5 second adhesive layer 10 polarizing plate with retardation layer

Claims (5)

A polarizer, a first retardation layer and a second retardation layer are provided in this order,
The polarizer and the first retardation layer are bonded together via a first adhesive layer,
The first retardation layer and the second retardation layer are bonded together via a second adhesive layer,
The thickness of the first retardation layer and the second retardation layer is 5 μm or less,
The second adhesive layer is composed of an active energy ray-curable adhesive containing a compound having an aromatic ring and acryloylmorpholine as curing components,
The average refractive index of the second adhesive layer is 1.55 or more, the difference from the average refractive index of the first retardation layer, and the difference from the average refractive index of the second retardation layer is 0 is less than .08;
A polarizing plate with a retardation layer. 2. The retardation layer-attached polarizing plate according to claim 1, wherein the average refractive index of the second adhesive layer is equal to or higher than the average refractive index of the second retardation layer. 3. The retardation layer-attached polarizing plate according to claim 1, wherein the thickness of said first adhesive layer and said second adhesive layer is 6 [mu]m or less. 4. The polarizing plate with a retardation layer according to claim 1, wherein the thickness from the polarizer to the second retardation layer is 35 [mu]m or less. 5. The polarizing plate with a retardation layer according to claim 1, wherein each of said first retardation layer and said second retardation layer is an alignment fixed layer of a liquid crystal compound.

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