JP5913648B1 - Polarizing plate with retardation layer and image display device - Google Patents

Abstract

The present invention provides a thin polarizing plate with a retardation layer that can be easily curled at the time of bonding, curled at the time of heating, and has excellent appearance durability at the time of heating. A polarizing plate with a retardation layer of the present invention includes a polarizing plate including a first protective layer, a polarizer, and a second protective layer, and a retardation layer. The thickness of the polarizing plate is 80 μm or less, and the thickness of the retardation layer is 60 μm or less. The difference between the thickness of the first protective layer and the thickness of the second protective layer is 10 μm or less, and the difference between the thickness of the polarizing plate and the thickness of the retardation layer is 25 μm or less. The thickness of the polarizer is 12 μm or less, the boric acid content is 18% by weight or more, the iodine content is 2.1% by weight or more, and the single transmittance is 44.0% to 45.5%. . [Selection] Figure 1

Description

  The present invention relates to a polarizing plate with a retardation layer and an image display device using the same.

  In recent years, image display devices typified by liquid crystal display devices and organic EL display devices have rapidly spread. Typically, an image display device uses a polarizing plate and a retardation plate. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1). Recently, there is a strong demand for thinning an image display device. Accordingly, there is an increasing demand for a thinner polarizing plate with a retardation layer. However, when trying to reduce the thickness of the polarizing plate with a retardation layer, it is difficult to adjust the curl at the time of bonding the polarizing plate and the retardation layer, and when the obtained polarizing plate with a retardation layer is heated, curling occurs. Or there is a problem that the appearance durability at the time of heating of the obtained polarizing plate with a retardation layer is insufficient and streaks occur. Attempting to improve any one of the above three problems makes the other one or two problems more prominent. A thin polarizing plate with a retardation layer that has solved all of these problems is still in practice. Is not obtained.

Japanese Patent No. 3325560

  The present invention has been made to solve the above-described conventional problems, and its main purpose is easy curl adjustment at the time of bonding, curling at the time of heating being suppressed, and appearance at the time of heating. An object of the present invention is to provide a thin polarizing plate with a retardation layer having excellent durability.

The polarizing plate with a retardation layer of the present invention includes a polarizing plate including a first protective layer, a polarizer, and a second protective layer, and a retardation layer. The thickness of the polarizing plate is 80 μm or less, and the thickness of the retardation layer is 60 μm or less. The difference between the thickness of the first protective layer and the thickness of the second protective layer is 10 μm or less, and the difference between the thickness of the polarizing plate and the thickness of the retardation layer is 25 μm or less. The thickness of the polarizer is 12 μm or less, the boric acid content is 18% by weight or more, the iodine content is 2.1% by weight or more, and the single transmittance is 44.0% to 45.5%. is there.
In one embodiment, the retardation layer is constituted by a resin film selected from a cyclic olefin resin film and a polycarbonate resin film.
In one embodiment, the retardation layer functions as a λ / 4 plate.
According to another aspect of the present invention, an image display device is provided. This image display device includes the above polarizing plate with a retardation layer.

  According to the present invention, in a thin polarizing plate with a retardation layer, the thickness of the polarizing plate and the polarizer and protective layer constituting the polarizing plate, the thickness of the retardation layer, and the difference in thickness between them are within a predetermined range. By optimizing and optimizing the boric acid content and iodine content of the polarizer, curl adjustment during bonding is easy, curling during heating is suppressed, and appearance during heating is further suppressed A thin polarizing plate with a retardation layer having excellent durability can be actually obtained.

It is a schematic sectional drawing of the polarizing plate with a phase difference layer by one Embodiment of this invention. 6 is a photographic image showing the appearance of a polarizing plate with a retardation layer of Comparative Example 4 after a heat resistance test.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

(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. For example, “Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) 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. For example, “Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is determined by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.

A. FIG. 1 is a schematic sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The retardation layer-attached polarizing plate 100 of the present embodiment includes a polarizing plate 10 and a retardation layer 20 disposed on one side of the polarizing plate 10. The polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11, and a second protective layer 13 disposed on the other side of the polarizer 11. . In the illustrated example, the retardation layer 20 is disposed on the second protective layer 13 side of the polarizing plate 10. In the embodiment of the present invention, the thickness of the polarizing plate 10 is 80 μm or less, and the thickness of the retardation layer 20 is 60 μm or less. The difference between the thickness of the first protective layer 12 and the thickness of the second protective layer 13 is 10 μm or less, and the difference between the thickness of the polarizing plate 10 and the thickness of the retardation layer 20 is 25 μm or less. Furthermore, the thickness of the polarizer 11 is 12 μm or less, the boric acid content is 18% by weight or more, the iodine content is 2.1% by weight or more, and the single transmittance is 44.0% to 45.5. %. Hereinafter, each layer and the optical film constituting the polarizing plate with a retardation layer will be described in more detail.

B. Polarizing plate B-1. Polarizer Any appropriate polarizer may be adopted as the polarizer 11. 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 iodine aqueous 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.

  Specific examples of the polarizer obtained using the laminate include a polarizer obtained using a laminate of a resin base material and a PVA-based resin layer applied and formed on the resin base material. For example, such a polarizer is formed by applying a PVA resin solution to a resin base material and drying it to form a PVA resin layer on the resin base material. Stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Further, 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 boric acid aqueous 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.

  As described above, the thickness of the polarizer is 12 μm or less, preferably 1 μm to 12 μm, and more preferably 3 μm to 12 μm. By making the thickness of the polarizer in the above range in the thin retardation film with retardation layer in which the difference between the thickness and thickness of the predetermined layer and the boric acid content and iodine content of the polarizer are optimized, Curling during heating can be satisfactorily suppressed while maintaining ease of curl adjustment at the time of pasting and suppressing streak and maintaining appearance durability during heating.

The boric acid content of the polarizer is 18% by weight or more as described above, and preferably 18% by weight to 25% by weight. Optimizing the iodine content described later by optimizing the boric acid content of the polarizer in such a range in a thin polarizing plate with a retardation layer with optimized thickness and thickness difference With the synergistic effect, the ease of curl adjustment at the time of bonding is well maintained, and curling at the time of heating is well controlled, while suppressing unevenness and improving the appearance durability during heating. be able to. The boric acid content can be calculated as the amount of boric acid contained in the polarizer per unit weight using, for example, the following formula from the neutralization method.

As described above, the iodine content of the polarizer is 2.1% by weight or more, and preferably 2.1% by weight to 3.5% by weight. Optimizing the boric acid content described above by optimizing the iodine content of the polarizer in such a range in a thin polarizing plate with a retardation layer in which the thickness and thickness difference of the predetermined layer are optimized With the synergistic effect, the ease of curl adjustment at the time of bonding is well maintained, and curling at the time of heating is well controlled, while suppressing unevenness and improving the appearance durability during heating. be able to. In this specification, “iodine content” means the amount of all iodine contained in a polarizer (PVA resin film). More specifically, in the polarizer, iodine exists in the form of iodine ions (I ⁻ ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ⁻ , I ₅ ⁻ ), etc. Iodine content means the amount of iodine encompassing all these forms. The iodine content can be calculated, for example, by a calibration curve method of fluorescent X-ray analysis. In addition, the polyiodine ion exists in the state which formed the PVA-iodine complex in the polarizer. By forming such a complex, absorption dichroism can be developed in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ions (PVA · I ₃ ⁻ ) has an absorption peak around 470 nm, and the complex of PVA and pentaiodide ions (PVA · I ₅ ⁻ ) is around 600 nm. Have an absorption peak. As a result, polyiodine ions can absorb light in a wide range of visible light depending on their form. On the other hand, iodine ion (I ⁻ ) has an absorption peak near 230 nm, and is not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in a complex state with PVA can be mainly involved in the absorption performance of the polarizer.

  It is one of the features of the present invention that the boric acid content and iodine content in the polarizer are in the above ranges. That is, the boric acid content and the iodine content as described above can cope with a new problem caused by setting the polarizer to a very thin thickness as described above, and the obtained polarizing plate is heated. It can contribute to the improvement of appearance durability. In more detail, it is as follows. In the past, it was difficult in the first place to industrially produce such a very thin polarizer, but in recent years it has become possible to produce such a very thin polarizer industrially. . Such a very thin polarizer was initially insufficient in both optical properties and durability. As a result of trial and error to solve such problems, by making the boric acid content and iodine content of the polarizer higher than that of the conventional thick polarizer, it is very thin and has optical characteristics It was also found that a polarizer having excellent durability was obtained. In addition, in a thin polarizing plate with a retardation layer in which the thickness and thickness difference of the predetermined layer are optimized, the boric acid content and iodine content of the polarizer are within the above ranges, so that at the time of bonding It has been found that the ease of curl adjustment can be maintained well and curling during heating can be satisfactorily suppressed while streaking is prevented and appearance durability during heating can be improved. This effect is a knowledge obtained for the first time by applying the boric acid content and iodine content as described above to the polarizer of the polarizing plate with a retardation layer having such a specific configuration, and is unexpectedly superior. Effect.

  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 44.0% to 45.5%, preferably 44.5% to 45.0%. Optimizing the boric acid content and iodine content described above when the single transmittance is optimized in such a range in the thin polarizing plate with retardation layer in which the thickness and thickness difference of the predetermined layer are optimized. By maintaining the ease of curl adjustment at the time of bonding with good synergistic effect, and suppressing curling during heating, suppressing streaks and improving appearance durability during heating Can do. It is estimated that there can be a critical point for the occurrence of streaks at a single transmittance slightly greater than 45.5%.

  The polarization degree of the polarizer is preferably 99.9% or more, more preferably 99.95% or more, and further preferably 99.98% or more. According to the present invention, curl adjustment at the time of bonding is easy, curling at the time of heating is suppressed, and furthermore, a thin polarizing plate with a retardation layer excellent in appearance durability at the time of heating is realized, Furthermore, in such a polarizing plate with a retardation layer, the above-described excellent degree of polarization can be realized.

B-2. First protective layer The first protective layer 12 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. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 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 composed 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.

  As will be described later, the polarizing plate with a retardation layer of the present invention is typically disposed on the viewing side of the image display device, and the first protective layer 12 is typically disposed on the viewing side. Therefore, the first protective layer 12 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.

  As the thickness of the first protective layer, any appropriate thickness can be adopted as long as the difference between the thickness of the desired polarizing plate and the thickness of the second protective layer can be obtained. The thickness of the first protective layer is, for example, 20 μm to 40 μm, and preferably 25 μm to 35 μm. In addition, when the surface treatment is performed, the thickness of the first protective layer is a thickness including the thickness of the surface treatment layer.

B-3. Second protective layer The second protective layer 13 is also formed of any suitable film that can be used as a protective layer for the polarizer. The material used as the main component of the film is as described in the section B-2 regarding the first protective layer. The second protective layer 13 is preferably optically isotropic. In this specification, “optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say.

  The thickness of the second protective layer is, for example, 15 μm to 35 μm, preferably 20 μm to 30 μm. As described above, the difference between the thickness of the first protective layer and the thickness of the second protective layer is 10 μm or less, preferably 7 μm or less. If the difference in thickness is within such a range, curling at the time of bonding can be satisfactorily suppressed. The thickness of the first protective layer and the thickness of the second protective layer may be the same, the first protective layer may be thicker, and the second protective layer may be thicker. . Typically, the first protective layer is thicker than the second protective layer.

B-4. Characteristics of the entire polarizing plate The thickness of the polarizing plate (the total thickness of the polarizer, the first protective layer and the second protective layer, and the adhesive layer on which these layers are laminated) is 80 μm or less as described above, preferably 50 μm. ˜70 μm. By making the thickness of the polarizing plate within such a range in the thin polarizing plate with retardation layer in which the thickness and thickness difference of the predetermined layer and the boric acid content and iodine content of the polarizer are optimized, heating is performed. It is possible to satisfactorily adjust the curling at the time of bonding while suppressing curling at the time and suppressing the unevenness and maintaining the appearance durability during heating.

C. Retardation Layer The retardation layer 20 can be composed of a retardation film having any appropriate optical property and / or mechanical property depending on the purpose. The retardation layer 20 typically has a slow axis. In one embodiment, the angle θ formed by the slow axis of the retardation layer 20 and the absorption axis of the polarizer 11 is preferably 38 ° to 52 °, more preferably 42 ° to 48 °. More preferably, it is about 45 °. If the angle θ is in such a range, by using a λ / 4 plate as the retardation layer as described later, it has a very excellent circular polarization characteristic (as a result, a very good antireflection characteristic). A polarizing plate with a retardation layer can be obtained.

  The retardation layer preferably has a relationship in refractive index characteristics of nx> ny ≧ nz. The retardation layer is typically provided for imparting antireflection properties to the polarizing plate, and can function as a λ / 4 plate in one embodiment. In this case, the in-plane retardation Re (550) of the retardation layer is preferably 80 nm to 200 nm, more preferably 100 nm to 180 nm, and still more preferably 110 nm to 170 nm. Here, “ny = nz” includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effects of the present invention are not impaired.

  The Nz coefficient of the retardation layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. . By satisfying such a relationship, when the obtained polarizing plate with a retardation layer is used in an image display device, a very excellent reflection hue can be achieved.

  The retardation layer may exhibit reverse dispersion wavelength characteristics in which the retardation value increases with the wavelength of the measurement light, or may exhibit positive wavelength dispersion characteristics in which the retardation value decreases with the wavelength of the measurement light. The phase difference value may exhibit a flat chromatic dispersion characteristic that hardly changes depending on the wavelength of the measurement light. In one embodiment, the retardation layer exhibits reverse dispersion wavelength characteristics. In this case, Re (450) / Re (550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized. In another embodiment, the retardation layer exhibits flat chromatic dispersion characteristics. In this case, Re (450) / Re (550) of the retardation layer is preferably from 0.99 to 1.03, and Re (650) / Re (550) is preferably from 0.98 to 1.02. . In this case, the retardation layer may have a laminated structure. Specifically, the retardation film functioning as a λ / 2 plate and the retardation film functioning as a λ / 4 plate are arranged at a predetermined axial angle (for example, 50 ° to 70 °, preferably about 60 °). Therefore, it is possible to obtain a characteristic close to an ideal inverse wavelength dispersion characteristic, and as a result, it is possible to realize a very excellent antireflection characteristic.

  The retardation layer has a water absorption of 3% or less, preferably 2.5% or less, more 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.

Retardation layer, the absolute value of photoelastic coefficient of preferably 2 × ¹⁰ -11 ^m 2 / N or less, more preferably ^{2.0 × 10 -13 m 2 /N~1.5×10 -11} m 2 / N, more preferably includes a resin of ^{1.0 × 10 -12 m 2 /N~1.2×10 -11} m 2 / N. When the absolute value of the photoelastic coefficient is in such a range, a phase difference change is unlikely to occur when a shrinkage stress is generated during heating. As a result, heat unevenness of the obtained image display apparatus can be prevented satisfactorily.

  As described above, the thickness of the retardation layer is 60 μm or less, preferably 40 μm to 55 μm. By setting the thickness of the retardation layer in such a range in the thin polarizing plate with a retardation layer in which the difference in thickness and thickness of the predetermined layer and the boric acid content and iodine content of the polarizer are optimized, It is possible to satisfactorily adjust the curling at the time of bonding while suppressing curling at the time of heating and suppressing streaking and maintaining the appearance durability at the time of heating.

  The difference between the thickness of the retardation layer 20 and the thickness of the polarizing plate 10 is 25 μm or less as described above, preferably 18 μm or less. Curling during heating is good by making the difference in thickness within this range in a thin polarizing plate with a retardation layer optimized for the predetermined layer thickness and the boric acid content and iodine content of the polarizer In addition, curling at the time of bonding can be well adjusted while suppressing streaking and maintaining appearance durability during heating. The thickness of the retardation layer and the thickness of the polarizing plate may be the same, the retardation layer may be thicker, or the polarizing plate may be thicker. Typically, the polarizing plate is thicker than the retardation layer.

  The retardation layer 20 can be composed of any appropriate resin film that can satisfy the above-described characteristics. Typical examples of such resins include cyclic olefin resins, polycarbonate resins, cellulose resins, polyester resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, acrylic resins. Based resins. Among these, a cyclic olefin resin or a polycarbonate resin can be suitably used.

  The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers. Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl- 2-Norbornene, 5-ethylidene-2-norbornene, etc. Polar group substitution products such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, alkyl and / or alkylidene substitution thereof And polar group substituents such as halogen, for example, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl -1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahi Lonaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene 4,11: 5,10: 6,9 Torimetano -3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a- dodecahydro -1H- cyclopentadiene anthracene, and the like.

  In the present invention, other cycloolefins capable of ring-opening polymerization can be used in combination as long as the object of the present invention is not impaired. Specific examples of such cycloolefins include compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

  The cyclic olefin-based resin preferably has a number average molecular weight (Mn) measured by a gel permeation chromatograph (GPC) method using a toluene solvent, preferably 25,000 to 200,000, more preferably 30,000 to 100,000. 000, most preferably 40,000-80,000. When the number average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  When the cyclic olefin-based resin is obtained by hydrogenating a ring-opening polymer of a norbornene monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, Most preferably, it is 99% or more. Within such a range, the heat deterioration resistance and light deterioration resistance are excellent.

  A commercially available film may be used as the cyclic olefin resin film. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “Arton” manufactured by JSR, “TOPAS” trade name manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

  The polycarbonate resin is preferably a structural unit derived from a dihydroxy compound represented by the following general formula (1), a structural unit derived from a dihydroxy compound represented by the following general formula (2), and the following general formula ( 3) a group consisting of a dihydroxy compound represented by the following general formula (4), a dihydroxy compound represented by the following general formula (5), and a dihydroxy compound represented by the following general formula (6) The structural unit derived from the 1 or more types of dihydroxy compound chosen more.

(In the general formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon atom having 6 to 20 carbon atoms. Or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, X is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, substituted or unsubstituted carbon number A cycloalkylene group having 6 to 20 carbon atoms or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, m and n are each independently an integer of 0 to 5).

(In the general formula (3), R ₅ represents a substituted or unsubstituted monocyclic cycloalkylene group having 4 to 20 carbon atoms.)

(In the general formula (4), R ₆ represents a substituted or unsubstituted monocyclic cycloalkylene group having 4 to 20 carbon atoms.)

(In the general formula (5), R ₇ represents a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and p is an integer of 2 to 100.)

(In the general formula (6), R ₁₁ represents an alkyl group having 2 to 20 carbon atoms or a group represented by the following formula (7).)

<Dihydroxy compound represented by the general formula (1)>
Specific examples of the dihydroxy compound represented by the general formula (1) include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-ethylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) ) Fluorene, 9,9-bis (4-hydroxy-3-n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy) -3-tert-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bi (4-hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) Fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isobutylphenyl) fluorene, 9,9- Bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3 5-dimethylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, 9,9-bis (4- (3-hydroxy-2, 2-dimethylpropoxy) phenyl) fluorene and the like are exemplified, and preferably 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene 9,9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) fluorene, particularly preferably 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene.

<Dihydroxy compound represented by the general formula (2)>
Examples of the dihydroxy compound represented by the general formula (2) include isosorbide, isomannide, and isoide which have a stereoisomeric relationship. These may be used alone or in combination of two or more. Among these dihydroxy compounds, isosorbide obtained by dehydrating condensation of sorbitol produced from various starches that are abundant as resources and are readily available is easy to obtain and manufacture, optical properties, moldability From the viewpoint of

<Dihydroxy compound represented by the general formula (3)>
Examples of the dihydroxy compound represented by the general formula (3) include a compound containing a monocyclic cycloalkylene group (an alicyclic dihydroxy compound). By setting it as a monocyclic structure, the toughness when the polycarbonate resin obtained is used as a film can be improved. Representative examples of the alicyclic dihydroxy compound include compounds having a 5-membered ring structure or a 6-membered ring structure. By being a 5-membered ring structure or a 6-membered ring structure, the heat resistance of the obtained polycarbonate resin can be increased. The six-membered ring structure may be fixed in a chair shape or a boat shape by a covalent bond. Specifically, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4- And cyclohexanediol. The dihydroxy compound represented by the general formula (3) may be used alone or in combination of two or more.

<Dihydroxy compound represented by the general formula (4)>
Examples of the dihydroxy compound represented by the general formula (4) include a compound containing a monocyclic cycloalkylene group (an alicyclic dihydroxy compound). By setting it as a monocyclic structure, the toughness when the polycarbonate resin obtained is used as a film can be improved. As a typical example of the alicyclic dihydroxy compound, R ₆ in the general formula (4) is the following general formula (Ia) (wherein R ³ is a hydrogen atom, or substituted or unsubstituted carbon number 1 to carbon number). Represents an alkyl group of 12)). Preferable specific examples of such isomers include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and the like. These are easily available and excellent in handleability. The dihydroxy compound represented by the general formula (4) may be used alone or in combination of two or more.

  In addition, the compound illustrated above regarding the dihydroxy compound represented with General formula (3) and (4) is an example of the alicyclic dihydroxy compound which can be used, Comprising: It is not limited to these at all.

<Dihydroxy compound represented by the general formula (5)>
Specific examples of the dihydroxy compound represented by the general formula (5) include diethylene glycol, triethylene glycol, and polyethylene glycol (molecular weight: 150 to 2000).

<Dihydroxy compound represented by the general formula (6)>
Specific examples of the dihydroxy compound represented by the general formula (6) include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and spiroglycol represented by the following formula (8). Among them, propylene glycol, 1,4-butanediol, and spiroglycol are preferable.

  Structural unit derived from dihydroxy compound represented by general formula (3), structural unit derived from dihydroxy compound represented by general formula (4), derived from dihydroxy compound represented by general formula (5) Among the structural units derived from the dihydroxy compound represented by the general formula (4) and / or the structural unit derived from the dihydroxy compound represented by the general formula (6) and / or the general formula (5) It is preferable that the structural unit derived from the dihydroxy compound represented by this is included, and it is more preferable that the structural unit derived from the dihydroxy compound represented by the said General formula (5) is included. By including the structural unit derived from the dihydroxy compound represented by the general formula (5), the stretchability can be improved.

The polycarbonate resin of this embodiment may further contain a structural unit derived from another dihydroxy compound.
<Other dihydroxy compounds>
Examples of other dihydroxy compounds include bisphenols. Examples of bisphenols include 2,2-bis (4-hydroxyphenyl) propane [= bisphenol A], 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis ( 4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) ) Propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4'-dihydroxy-diphenylmethane, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-5-nitrophenyl) methane, 1,1 -Bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydride) Roxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4′-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3 Examples include '-dichlorodiphenyl ether and 4,4'-dihydroxy-2,5-diethoxydiphenyl ether.

  In the polycarbonate resin, the structural unit derived from the dihydroxy compound represented by the general formula (1) is 18 mol% or more, preferably 20 mol% or more, and more preferably 25 mol% or more. If the structural unit is too small, the wavelength dependence of reverse dispersion may not be obtained.

  The dihydroxy compound represented by the general formula (3), the dihydroxy compound represented by the general formula (4), the dihydroxy compound represented by the general formula (5), and the dihydroxy represented by the general formula (6) The structural unit derived from one or more dihydroxy compounds selected from the group consisting of compounds is preferably 25 mol% or more, more preferably 30 mol% or more, and still more preferably 35 mol% or more in the polycarbonate resin. It is. If the number of structural units is too small, the toughness of the film may be poor.

  The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 150 ° C. or lower, more preferably 120 ° C. or higher and 140 ° 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.

  A commercially available film may be used as the polycarbonate resin film. Specific examples of commercially available products include Teijin's trade names “Pure Ace WR-S”, “Pure Ace WR-W”, “Pure Ace WR-M”, and Nitto Denko's trade names “NRF”. It is done.

  The retardation layer 20 is obtained, for example, by stretching a film formed from the cyclic olefin resin or the polycarbonate resin. As a method for forming a film from a cyclic olefin-based resin or a polycarbonate-based resin, any appropriate molding method can be adopted. Specific examples include compression molding methods, transfer molding methods, injection molding methods, extrusion molding methods, blow molding methods, powder molding methods, FRP molding methods, cast coating methods (for example, casting methods), calendar molding methods, and hot presses. Law. Extrusion molding or cast coating is preferred. This is because the smoothness of the resulting film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the properties desired for the retardation layer, and the like. As described above, since many film products are commercially available for the cyclic olefin-based resin and the polycarbonate-based resin, the commercially available film may be subjected to a stretching treatment as it is.

  The thickness of the resin film (unstretched film) can be set to any appropriate value depending on the desired thickness of the retardation layer, the desired optical properties, the stretching conditions described below, and the like. Preferably it is 50 micrometers-300 micrometers.

  Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) can be adopted 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 length direction, a width direction, a thickness direction, and an oblique direction. The stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, and more preferably Tg-10 ° C to Tg + 50 ° C, with respect to the glass transition temperature (Tg) of the resin film.

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

  In one embodiment, the retardation film is produced by uniaxially stretching a resin film or uniaxially stretching a fixed end. As a specific example of the fixed end uniaxial stretching, there is a method of stretching in the width direction (lateral direction) while running the resin film in the longitudinal direction. The draw ratio is preferably 1.1 times to 3.5 times.

  In another embodiment, the retardation film can be produced by continuously and obliquely stretching a long resin film in the direction of the angle θ described above 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. Note that the angle θ may be an angle formed between the absorption axis of the polarizer and the slow axis of the retardation layer in the polarizing plate with the retardation layer. As described above, the angle θ is preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and further preferably about 45 °.

  Examples of the stretching machine used for the oblique stretching include a tenter-type stretching machine that can apply a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or longitudinal direction. 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.

  By appropriately controlling the left and right velocities in the stretching machine, the retardation layer having the desired in-plane retardation and having the slow axis in the desired direction (substantially long) Shaped retardation film) can be obtained.

  The stretching temperature of the film can vary depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably Tg-30 ° C to Tg + 30 ° C, more preferably Tg-15 ° C to Tg + 15 ° C, and most preferably Tg-10 ° C to Tg + 10 ° C. By stretching at such a temperature, a retardation layer having appropriate characteristics in the present invention can be obtained. Tg is the glass transition temperature of the constituent material of the film.

D. Others The polarizing plate with a retardation layer according to the embodiment of the present invention may further include another retardation layer. The optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of other retardation layers can be appropriately set according to the purpose.

  Arbitrary appropriate adhesive layers or adhesive layers are used for lamination of each layer which constitutes the polarizing plate with a phase contrast 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 is provided on the surface of the retardation layer 20 of the polarizing plate with the retardation layer (the surface of the outermost retardation layer when other retardation layers are provided). Also good. By providing the pressure-sensitive adhesive layer in advance, it can be easily bonded to another optical member or an image display device. In addition, it is preferable that the peeling film is bonded together on the surface of this adhesive layer until it uses.

E. Image Display Device The polarizing plate with a retardation layer described in the items A to D can be applied to an image display device. Therefore, this invention includes the image display apparatus using such a polarizing plate with a phase difference layer. Typical examples of the image display device include a liquid crystal display device and an organic EL display device. An image display device according to an embodiment of the present invention includes the polarizing plate with a retardation layer described in the items A to D on the viewing side. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the display panel (for example, a liquid crystal panel or an organic EL panel) (so that the polarizer is on the viewing side).

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method of each characteristic is as follows.

(1) Thickness The thickness was measured using a digital micrometer (KC-351C manufactured by Anritsu Corporation).
(2) Single transmittance of polarizer The single transmittance measured using an ultraviolet-visible spectrophotometer (V7100 manufactured by JASCO Corporation) for the polarizing plates used in Examples and Comparative Examples was defined as the transmittance of the polarizer. Note that the transmittance here is a Y value measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for visibility.
(3) Content of Boric Acid in Polarizer The polarizer used in Examples and Comparative Examples was dried by heating (120 ° C., 2 hours) and then pulverized to obtain a sample for evaluation having a weight of 1 g. All 1 g of the sample for evaluation was dissolved in 500 ml of water at 95 ° C. A sample solution was prepared by adding 10 g of mannitol and 2 ml of bromothymol blue solution (BTB solution) to the obtained aqueous solution. To this sample solution, 0.1 mol / l sodium hydroxide was dropped until the neutralization point was reached, and the boric acid content ratio (% by weight) was calculated from the dripping amount based on the following formula.
(4) Iodine Content of Polarizer The polarizer used in Examples and Comparative Examples was cut into a predetermined size and used as an evaluation sample. With respect to the prepared sample for evaluation, the iodine concentration was quantified using a calibration curve method of fluorescent X-ray analysis. The apparatus used was a fluorescent X-ray analyzer ZSX manufactured by Rigaku Corporation.
(5) Retardation value and Nz coefficient of retardation layer A sample of 50 mm × 50 mm was cut out from the retardation layer used in Examples and Comparative Examples to obtain a measurement sample. About the produced measurement sample, in-plane phase difference and thickness direction phase difference were measured using Axoscan made from Axometrics. The in-plane retardation measurement wavelengths were 450 nm and 550 nm, the thickness direction retardation measurement wavelength was 550 nm, and the measurement temperature was 23 ° C. The Nz coefficient was calculated from the obtained in-plane retardation and thickness direction retardation.
(6) Curling adjustment at the time of pasting About the pasting of a polarizing plate and a phase difference layer, the tension on the side of the polarizing plate at the time of pasting and the tension on the side of the phase difference layer are made the same, and the laminated film is The curled state of what was cut out to 100 mm x 100 mm size was confirmed.
Easy adjustment (good): Curling amount is 10 mm or less Difficult adjustment (unsuitable): Curling amount exceeds 10 mm (7) Curling during heating The polarizing plate with retardation layer obtained in Examples and Comparative Examples is 100 mm × 100 mm size And stored in an 85 ° C. heating oven for 30 minutes, and then the curled state in the state where the film was removed and the release film was peeled off was confirmed. The evaluation criteria are as follows.
Permissible range: Curling amount is 10 mm or less Unsuitable: Curling amount exceeds 10 mm (8) Appearance durability during heating Cover glass and reflection on the surface of a smartphone (product name “Galaxy-S5”) manufactured by Samsung Electronics Japan Co., Ltd. The prevention film was peeled off, and the polarizing plate with a retardation layer obtained in Examples and Comparative Examples was bonded to the peeled surface through an acrylic pressure-sensitive adhesive (thickness: 15 μm) to obtain a sample for evaluation. The sample for evaluation was stored in an oven at 85 ° C. for 240 hours and then taken out, and the appearance was visually confirmed. The evaluation criteria are as follows.
Good: No streaky irregularities are observed. Bad: Streaky irregularities are visible.

[Reference Example 1: Production of polarizing plate]
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 that it becomes 5.9 times in the longitudinal direction by a roll stretching machine. At the same time, swelling, dyeing, crosslinking, and washing treatment were performed, and finally a drying treatment was performed to produce a polarizer 1 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 1.
A TAC film manufactured by Konica Minolta Co., Ltd. (product name: KC2UA, thickness: 25 μm, corresponding to the second protective layer) and the TAC film on both surfaces of the obtained polarizer 1 through a polyvinyl alcohol adhesive. HC-TAC films (thickness: 32 μm, corresponding to the first protective layer) each having a hard coat (HC) layer formed by a hard coat process on one side of each of the first protective layer / polarizer A polarizing plate 1 having a configuration of 1 / second protective layer was obtained.

[Reference Example 2: Preparation of polarizing plate]
The use of a long roll of polyvinyl alcohol (PVA) resin film (product name “PE2000”, manufactured by Kuraray Co., Ltd.) having a thickness of 20 μm, and the dye solution so that the single transmittance of the obtained polarizer is 44.5%. A polarizer 2 having a thickness of 8 μm was obtained in the same manner as in Reference Example 1 except that the iodine concentration was adjusted and the draw ratio during the second-stage crosslinking treatment was 1.5 times. A polarizing plate 2 having a configuration of first protective layer / polarizer 2 / second protective layer was obtained in the same manner as in Reference Example 1 except that this polarizer 2 was used.

[Reference Example 3: Production of Polarizing Plate]
A polarizer 3 having a thickness of 23 μm was obtained in the same manner as in Reference Example 1, except that a long roll of a polyvinyl alcohol (PVA) resin film having a thickness of 60 μm (made by Kuraray, product name “PE6000”) was used.
An HC-TAC film having an HC layer formed by HC treatment on one side of a TAC film (product name: KC4UY) manufactured by Konica Minolta Co., Ltd. on both surfaces of the obtained polarizer 3 through a polyvinyl alcohol adhesive. (Thickness: 46 μm, corresponding to the first protective layer) and an acrylic film (thickness: 20 μm, corresponding to the second protective layer) were bonded together, and the first protective layer / polarizer 3 / second A polarizing plate 3 having a protective layer structure was obtained.

[Reference Example 4: Production of Polarizing Plate]
A TAC film manufactured by Konica Minolta Co., Ltd. (product name: KC2UA thickness: 25 μm, corresponding to the second protective layer) on both sides of the polarizer 3 obtained in Reference Example 3 via a polyvinyl alcohol-based adhesive, and An HC-TAC film (thickness: 32 μm, corresponding to the first protective layer) having an HC layer formed by HC treatment on one side of the TAC film was bonded to each other, and the first protective layer / polarizer 3 / A polarizing plate 4 having the configuration of the second protective layer was obtained.

[Reference Example 5: Production of polarizing plate]
A polarizer 5 was produced in the same manner as in Reference Example 1 except that the iodine concentration of the staining solution was adjusted so that the single transmittance of the polarizer was 45.6%. A polarizing plate 5 having a configuration of first protective layer / polarizer 5 / second protective layer was obtained in the same manner as in Reference Example 1 except that this polarizer 5 was used.

[Reference Example 6: Production of polarizing plate]
A polarizer 6 was produced in the same manner as in Reference Example 1 except that the boric acid content of the aqueous solution of the second crosslinking treatment was 3.0% by weight. A polarizing plate 6 having a first protective layer / polarizer 6 / second protective layer configuration was obtained in the same manner as in Reference Example 1 except that this polarizer 6 was used.

[Reference Example 7: Production of retardation film constituting retardation layer]
7-1. Production of Polycarbonate Resin Film Isosorbide (ISB) 26.2 parts by mass, 9,9- [4- (2-hydroxyethoxy) phenyl] fluorene (BHEPF) 100.5 parts by mass, 1,4-cyclohexanedimethanol (1, 4-CHDM) 10.7 parts by mass, diphenyl carbonate (DPC) 105.1 parts by mass, and 0.591 parts by mass of cesium carbonate (0.2% by mass aqueous solution) as a catalyst were put into a reaction vessel, respectively, and a nitrogen atmosphere Below, as a process of the first step of the reaction, the heating medium temperature of the reaction vessel was set to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes).
Next, the pressure in the reaction vessel was changed from normal pressure to 13.3 kPa, and the generated phenol was extracted out of the reaction vessel while the temperature of the heat medium in the reaction vessel was increased to 190 ° C. over 1 hour.
After maintaining the reaction vessel temperature at 190 ° C. for 15 minutes, as a second step, the pressure in the reaction vessel is set to 6.67 kPa, and the heat medium temperature of the reaction vessel is increased to 230 ° C. in 15 minutes. The generated phenol was extracted out of the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250 ° C. in 8 minutes, and the pressure in the reaction vessel was reduced to 0.200 kPa or less in order to remove the generated phenol. After reaching the predetermined stirring torque, the reaction was terminated, and the formed reaction product was extruded into water, and then pelletized to obtain BHEPF / ISB / 1,4-CHDM = 47.4 mol% / 37.1 mol%. /15.5 mol% polycarbonate resin was obtained.
The obtained polycarbonate resin had a glass transition temperature of 136.6 ° C. and a reduced viscosity of 0.395 dL / g.
The obtained polycarbonate resin was vacuum-dried at 80 ° C. for 5 hours, and then a single-screw extruder (made by Isuzu Chemical Industries, screw diameter 25 mm, cylinder set temperature: 220 ° C.), T-die (width 200 mm, set temperature: 220). ° C), a chill roll (set temperature: 120 to 130 ° C), and a film forming apparatus equipped with a winder, a polycarbonate resin film having a thickness of 120 µm was produced.

7-2. Production of Retardation Film Using a tenter stretching machine, the obtained polycarbonate resin film was horizontally stretched to obtain a retardation film having a thickness of 50 μm. At that time, the draw ratio was 250%, and the draw temperature was 137 to 139 ° C.
Re (550) of the obtained retardation film is 137 to 147 nm, Re (450) / Re (550) is 0.89, Nz coefficient is 1.21, orientation angle (slow axis) Direction) was 90 ° with respect to the longitudinal direction. This retardation film was used as the retardation layer 1.

[Reference Example 8: Retardation film constituting retardation layer]
A commercially available cycloolefin phase difference film (manufactured by Nippon Zeon Co., Ltd., product name “Zeonor film”, thickness: 47 μm, Re (550) = 140 μm) was used as it was to obtain a phase difference layer 2.

[Reference Example 9: Production of retardation film constituting retardation layer]
Kaneka's cycloolefin phase difference film A (product name: KUZ-film # 270, thickness: 33 μm, Re (550) = 270 nm) and Kaneka's cycloolefin phase difference film B (product) Name: KUZ-film # 140, thickness: 28 μm, Re (550) = 140 nm) are bonded together via an acrylic adhesive layer having a thickness of 5 μm so that the angle formed by each slow axis is 60 ° C. Thus, a laminated retardation film was obtained. This laminated retardation film was designated as retardation layer 3.

[Example 1]
The second protective layer of the polarizing plate 1 and the retardation layer 1 are interposed through an acrylic adhesive layer having a thickness of 12 μm so that the angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer is 45 °. To obtain a polarizing plate 1 with a retardation layer. The obtained polarizing plate 1 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Example 2]
A polarizing plate 2 with a retardation layer was obtained in the same manner as in Example 1 except that the polarizing plate 2 was used. The obtained polarizing plate 2 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Example 3]
A polarizing plate 3 with a retardation layer was obtained in the same manner as in Example 1 except that the retardation layer 2 was used. The obtained polarizing plate 3 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Comparative Example 1]
The angle formed by the second protective layer of the polarizing plate 3 and the retardation film A of the retardation layer 3 between the absorption axis of the polarizer and the slow axis of the retardation film A is 15 °, and the absorption axis of the polarizer And a retardation layer B with a retardation axis so that the angle between the retardation axis and the slow axis of the retardation film B is 75 °. The obtained polarizing plate 4 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Comparative Example 2]
A polarizing plate 5 with a retardation layer was obtained in the same manner as in Example 1 except that the polarizing plate 3 was used. The obtained polarizing plate 5 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Comparative Example 3]
A polarizing plate 6 with a retardation layer was obtained in the same manner as in Comparative Example 1 except that the polarizing plate 4 was used. The obtained polarizing plate 6 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

[Comparative Example 4]
A polarizing plate 7 with a retardation layer was obtained in the same manner as in Example 1 except that the polarizing plate 5 was used. The obtained polarizing plate 7 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1. Furthermore, the photographic image which shows the external appearance after a heat test is shown in FIG.

[Comparative Example 5]
A polarizing plate 8 with a retardation layer was obtained in the same manner as in Example 1 except that the polarizing plate 6 was used. The obtained polarizing plate 8 with retardation layer was subjected to the evaluations (6) to (8) above. The results are shown in Table 1.

<Evaluation>
As can be seen from Table 1, the polarizing plates with retardation layers of the examples of the present invention have good results in ease of curl adjustment during bonding, curl suppression during heating, and appearance durability during heating. was gotten. On the other hand, at least one of such evaluation characteristics was insufficient for the polarizing plate with a retardation layer of the comparative example. That is, according to the present invention, all the above three evaluation characteristics that have been difficult in the prior art are satisfied by optimizing the predetermined requirements of the polarizing plate and the retardation layer constituting the polarizing plate with the retardation layer. It can be seen that a thin polarizing plate with a retardation layer is obtained.

  The polarizing plate with a retardation layer of the present invention is suitably used for image display devices such as liquid crystal display devices and organic EL display devices.

DESCRIPTION OF SYMBOLS 10 Polarizing plate 11 Polarizer 12 First protective layer 13 Second protective layer 20 Retardation layer 100 Polarizing plate with retardation layer

Claims (4)

A polarizing plate including a first protective layer, a polarizer, and a second protective layer, and a retardation layer, wherein the thickness of the polarizing plate is 80 μm or less, and the thickness of the retardation layer is 60 μm or less,
The difference between the thickness of the first protective layer and the thickness of the second protective layer is 10 μm or less,
The difference between the thickness of the polarizing plate and the thickness of the retardation layer is 25 μm or less,
The thickness of the polarizer is 12 μm or less, the boric acid content is 18 wt% to 25 wt% , the iodine content is 2.1 wt% to 3.5 wt% , and the single transmittance is 44. % . 0% to 45.5%,
Polarizing plate with retardation layer.   The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer is composed of a resin film selected from a cyclic olefin resin film and a polycarbonate resin film.   The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer functions as a λ / 4 plate. An image display device comprising the polarizing plate with a retardation layer according to claim 1.