阅读说明：本技术 带相位差层的偏振片及图像显示装置 (Polarizing plate with phase difference layer and image display device ) 是由 喜多川丈治 形见普史 后藤周作 于 2018-05-25 设计创作，主要内容包括：本发明提供一种带相位差层的偏振片,其可实现具有优异的耐久性及耐候性、并且具有优异的色相的图像显示装置。本发明的带相位差层的偏振片依次具有偏振片、相位差层和粘合剂层,所述偏振片具有保护层及起偏器。保护层的波长380nm的光线透射率为10％以下,偏振片的波长380nm的光线透射率为5％以下,粘合剂层的波长405nm的光线透射率为5％以下,带相位差层的偏振片的波长405nm的光线透射率为3％以下。(The invention provides a polarizing plate with a phase difference layer, which can realize an image display device with excellent durability, weather resistance and hue. The polarizing plate with a retardation layer of the present invention comprises a polarizing plate, a retardation layer and an adhesive layer in this order, and the polarizing plate comprises a protective layer and a polarizer. The light transmittance at a wavelength of 380nm of the protective layer is 10% or less, the light transmittance at a wavelength of 380nm of the polarizing plate is 5% or less, the light transmittance at a wavelength of 405nm of the adhesive layer is 5% or less, and the light transmittance at a wavelength of 405nm of the polarizing plate with the retardation layer is 3% or less.)

1. A polarizing plate with a retardation layer, which comprises a polarizing plate having a protective layer and a polarizer, a retardation layer and an adhesive layer in this order,

the protective layer has a light transmittance of 10% or less at a wavelength of 380nm,

the polarizer has a light transmittance of 5% or less at a wavelength of 380nm,

the light transmittance of the adhesive layer at a wavelength of 405nm is 5% or less,

the polarizing plate with a retardation layer has a light transmittance at a wavelength of 405nm of 3% or less.

2. The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer is composed of a polycarbonate-based resin film.

3. The polarizing plate with a retardation layer according to claim 2, wherein another retardation layer is further provided between the retardation layer and the adhesive layer.

4. The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer is an alignment cured layer of a liquid crystal compound.

5. The polarizing plate with a phase difference layer according to claim 4, wherein the phase difference layer has a laminated structure of an alignment cured layer of a 1 st liquid crystal compound and an alignment cured layer of a 2 nd liquid crystal compound.

6. The polarizing plate with a phase difference layer according to any one of claims 1 to 5, wherein the thickness of the polarizer is 10 μm or less.

7. The polarizing plate with a retardation layer according to any one of claims 1 to 6, wherein the protective layer has a thickness of 30 μm or less.

8. The polarizing plate with a retardation layer according to claim 7, wherein the protective layer has a moisture permeability of 20g/m²24 hours or less.

9. The polarizing plate with a phase difference layer according to any one of claims 1 to 8, wherein the polarizing plate is directly laminated with the phase difference layer.

10. The polarizing plate with a retardation layer according to any one of claims 1 to 9, wherein b x value of a reflection hue of the polarizing plate is-1.5 or less.

11. The polarizing plate with a phase difference layer according to any one of claims 1 to 10, wherein the polarizer has an orthochromatic phase b value of-1.5 or less.

12. The polarizing plate with a phase difference layer according to any one of claims 1 to 11, wherein a conductive layer or an isotropic substrate with a conductive layer is further provided between the phase difference layer and the adhesive layer.

13. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 12.

Technical Field

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

Background

In recent years, image display devices typified by liquid crystal display devices and organic EL display devices have rapidly spread. Typically, a polarizing plate and a retardation plate are used in an image display device. In practical terms, polarizing plates with a retardation layer, which are obtained by integrating a polarizing plate and a retardation plate, are widely used (for example, patent document 1), and recently, with the increasing demand for the reduction in thickness of an image display device, the demand for the reduction in thickness of a polarizing plate with a retardation layer is also increasing.

However, an image display device (particularly, an organic EL display device) has a problem that the characteristics are deteriorated with time (weather resistance is insufficient) by ultraviolet rays. In order to improve the durability of image display devices, techniques for imparting ultraviolet absorption capability to optical films used in image display devices have been studied. However, this technique has a problem that the hue changes and desired display characteristics cannot be obtained.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above conventional problems, and a main object thereof is to provide a polarizing plate with a retardation layer that can realize an image display device having excellent durability and weather resistance and having an excellent hue.

Means for solving the problems

The polarizing plate with a retardation layer of the present invention comprises a polarizing plate, a retardation layer and an adhesive layer in this order, and the polarizing plate comprises a protective layer and a polarizer. The protective layer has a light transmittance at a wavelength of 380nm of 10% or less, the polarizing plate has a light transmittance at a wavelength of 380nm of 5% or less, the adhesive layer has a light transmittance at a wavelength of 405nm of 5% or less, and the polarizing plate with a retardation layer has a light transmittance at a wavelength of 405nm of 3% or less.

In one embodiment, the retardation layer is made of a polycarbonate resin film. In this embodiment, the polarizing plate with a retardation layer may further include another retardation layer between the retardation layer and the pressure-sensitive adhesive layer.

In one embodiment, the retardation layer is an alignment cured layer of a liquid crystal compound. In this embodiment, the retardation layer may have a laminated structure of a 1 st alignment cured layer of a liquid crystal compound and a 2 nd alignment cured layer of a liquid crystal compound.

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

In one embodiment, the protective layer has a thickness of 30 μm or less.

In one embodiment, the protective layer has a moisture permeability of 20g/m²24h or less.

In one embodiment, the polarizing plate and the retardation layer are directly laminated.

In one embodiment, b-value of the reflection hue of the polarizing plate is-1.5 or less.

In one embodiment, the value of b of the orthochromatic phase of the polarizer is-1.5 or less.

In one embodiment, the polarizing plate with a retardation layer further includes a conductive layer or an isotropic substrate with a conductive layer between the retardation layer and the pressure-sensitive adhesive layer.

According to another aspect of the present invention, there is provided an image display device. The image display device includes the polarizing plate with a retardation layer.

Effects of the invention

According to the present invention, in the retardation layer-equipped polarizing plate, the transmittance of light having a predetermined wavelength is controlled in the protective layer, the polarizing plate, the adhesive layer, and the retardation layer-equipped polarizing plate, whereby a retardation layer-equipped polarizing plate capable of realizing an image display device having excellent durability and weather resistance and having excellent hue can be obtained.

Drawings

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

Fig. 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention.

Detailed Description

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

(definitions of wording and symbols)

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

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

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

(2) In-plane retardation (Re)

"Re (λ)" is an in-plane phase difference obtained by light measurement at a wavelength of λ nm at 23 ℃. For example, "Re (550)" is an in-plane retardation measured at 23 ℃ with light having a wavelength of 550 nm. When the thickness of the layer (film) is d (nm), Re (λ) is expressed by the following formula: re (λ) ═ (nx-ny) × d.

(3) Retardation in thickness direction (Rth)

"Rth (λ)" is a phase difference in the thickness direction obtained by light measurement at a wavelength of λ nm at 23 ℃. For example, "Rth (550)" is a phase difference in the thickness direction obtained by light measurement at a wavelength of 550nm at 23 ℃. When the thickness of the layer (film) is d (nm), Rth (λ) is expressed by the following formula: rth (λ) ═ n x-nz × d.

(4) Coefficient of Nz

The Nz coefficient is determined by Nz ═ Rth/Re.

A. Integral constitution of polarizing plate with phase difference layer

Fig. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to an embodiment of the present invention. The polarizing plate with retardation layer 100 of the present embodiment includes a polarizing plate 10, a retardation layer 20, and an adhesive layer 30 in this order. The polarizing plate 10 includes a polarizer 11 and a protective layer 12 disposed on one side of the polarizer 11 (typically, on the opposite side of the retardation layer 20). If necessary, another protective layer (not shown) may be provided on the other side of the polarizer (typically, the retardation layer 20 side).

In one embodiment, the retardation layer 20 is composed of a resin film. In this embodiment, as shown in fig. 2, the polarizing plate 101 with a retardation layer may further include another retardation layer 40 between the retardation layer 20 and the adhesive layer 30. Hereinafter, for convenience, the retardation layer 20 may be referred to as a 1 st retardation layer, and the other retardation layer 40 may be referred to as a 2 nd retardation layer.

In another embodiment, the 1 st retardation layer 20 may be an alignment cured layer of a liquid crystal compound. In this embodiment, the 1 st retardation layer 20 may be a single layer, or may have a laminated structure of a 1 st orientation cured layer 21 and a 2 nd orientation cured layer 22 as shown in fig. 3.

If necessary, a conductive layer or an isotropic substrate with a conductive layer (not shown) may be provided. The conductive layer or the isotropic substrate with a conductive layer is typically provided on the side of the retardation layer 20 opposite to the polarizing plate 10, more specifically, between the retardation layer 20 (the 2 nd retardation layer 40 in the case where the 2 nd retardation layer 40 is present) and the adhesive layer 30. In the case of providing a conductive layer or an isotropic substrate with a conductive layer, a polarizing plate with a retardation layer can be applied to a so-called in-cell touch panel type input display device in which a touch sensor is incorporated between a display unit (for example, an organic EL unit) and a polarizing plate.

In one embodiment, the polarizing plate 10 (polarizer 11 in the example of the figure) and the phase difference layer are directly laminated. With such a configuration, the polarizing plate with a retardation layer (and consequently, the image display device) can be further thinned. In the present specification, "directly laminated" means a state in which the laminate is laminated with only an adhesive or a bonding agent without interposing an intermediate layer. Further, "directly laminated" also includes a state in which the polarizing plate and the retardation layer are directly laminated as they are without using an adhesive or a bonding agent.

In the embodiment of the present invention, the protective layer 12 has a light transmittance at a wavelength of 380nm of 10% or less, preferably 9% or less, and more preferably 8.7% or less. The polarizer 10 has a light transmittance at a wavelength of 380nm of 5% or less, preferably 3% or less, and more preferably 2% or less. The light transmittance of the pressure-sensitive adhesive layer 30 at a wavelength of 405nm is 5% or less, preferably 3% or less, and more preferably 1% or less. Further, the polarizing plate with a retardation layer has a light transmittance at a wavelength of 405nm of 3% or less, preferably 2.5% or less, and more preferably 2% or less. The light transmittance can be measured using a spectrophotometer in accordance with JIS K0115. In one embodiment, the value b of the reflected hue of the polarizer 10 is preferably-1.5 or less, more preferably-1.9 or less. In one embodiment, the value of b for the crossed hue of the polarizer 11 is preferably-1.5 or less, more preferably-2.5 or less. According to the embodiments of the present invention, both of the ultraviolet absorptivity and the hue can be very excellent. As a result, the polarizing plate with a retardation layer of the present invention can realize an image display device (particularly, an organic EL display device) excellent in both weather resistance and hue.

The total thickness of the polarizing plate with a retardation layer is preferably 140 μm or less, more preferably 120 μm, and still more preferably 110 μm or less. The lower limit of the total thickness is, for example, 60 μm. In the embodiment where the retardation layer is an alignment cured layer of a liquid crystal compound, the total thickness is preferably 60 μm or less, and more preferably 55 μm or less. The lower limit of the total thickness in this embodiment is, for example, 35 μm. According to the present invention, it is possible to achieve a significantly thin profile in addition to the excellent ultraviolet absorptivity and hue described above. The total thickness of the polarizing plate with a retardation layer is the total thickness of the protective layer 12, the polarizer 11, the retardation layer 20 (and the 2 nd retardation layer 40 if present), and the adhesive layer (adhesive layer, pressure-sensitive adhesive layer) and the pressure-sensitive adhesive layer 30 for laminating them.

The polarizing plate with a retardation layer may be a single sheet or a long sheet. The term "elongated shape" as used herein means an elongated shape having a length sufficiently long with respect to a width, and includes, for example, an elongated shape having a length 10 times or more, preferably 20 times or more with respect to a width. The long polarizing plate with a retardation layer may be wound in a roll shape.

In practical use, it is preferable that a release film is temporarily bonded to the surface of the pressure-sensitive adhesive layer 30 until a polarizing plate with a retardation layer is used. By temporarily adhering the release film, the adhesive layer can be protected, and a roll can be formed.

Hereinafter, each layer, optical film and adhesive constituting the polarizing plate with a retardation layer will be described in more detail.

B. Polarizing plate

B-1 polarizer

As the polarizer 11, any suitable polarizer can be used. 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 polarizers obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or an ethylene-vinyl acetate copolymer partially saponified film to dyeing treatment or stretching treatment with a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as a PVA dehydrated product or a polyvinyl chloride desalted acid-treated product. From the viewpoint of excellent optical properties, it is preferable to use a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film.

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

Specific examples of the polarizer obtained using the laminate include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by: coating a PVA-based resin solution on a resin base material and drying the PVA-based resin solution to form a PVA-based resin layer on the resin base material, thereby obtaining a laminate of the resin base material and the PVA-based resin layer; the laminate is stretched and dyed to form a polarizer from the PVA resin layer. In the present embodiment, the stretching representatively includes immersing the laminate in an aqueous boric acid solution and stretching. Further, the stretching may further include subjecting the laminate to in-air stretching at a high temperature (for example, 95 ℃ or higher) before stretching in the 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 a polarizer), or the resin substrate may be peeled from the resin substrate/polarizer laminate and an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of a method for producing such a polarizer are described in, for example, japanese patent laid-open No. 2012-73580. The entire disclosure of this publication is incorporated herein by reference.

The thickness of the polarizer is preferably 10 μm or less, more preferably 8 μm or less, further preferably 6 μm or less, and particularly preferably 5 μm or less. The lower limit of the thickness of the polarizer is, for example, 1 μm. According to the present invention, when the thickness of the polarizer is in such a range, it is possible to achieve a significant reduction in thickness of the polarizing plate with a retardation layer, and it is possible to achieve both excellent ultraviolet absorptivity and excellent hue in the polarizing plate with a retardation layer. In addition, if the thickness of the polarizer is in such a range, curling during heating can be favorably suppressed, and favorable durability of appearance during heating can be obtained.

The boric acid content of the polarizer is preferably 18% by weight or more, more preferably 18% by weight to 25% by weight. When the boric acid content of the polarizer is in such a range, the curling can be favorably controlled and the appearance durability can be improved during heating while maintaining the easiness of curling adjustment during bonding and favorably suppressing the curling during heating by a synergistic effect with the iodine content described below. The boric acid content can be calculated, for example, by a neutralization method using the following formula as the amount of boric acid contained in the polarizer per unit weight.

The iodine content of the polarizer is preferably 2.1 wt% or more, and more preferably 2.1 wt% to 3.5 wt%. When the iodine content of the polarizer is in such a range, the curling can be favorably controlled and the appearance durability can be improved during heating while maintaining the easiness of curling adjustment during bonding and favorably suppressing the curling during heating by the synergistic effect with the boric acid content. In the present specification, the "iodine content" refers to the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, iodine is doped with iodide ion (I) in the polarizer^-) Iodine molecule (I)₂) Polyiodide (I)₃ ^-、I₅ ^-) The iodine content in the present specification means the amount of iodine including all of these forms. The iodine content can be calculated, for example, by a calibration curve method of fluorescent X-ray analysis. It should be noted that the polyiodide is in the polarizer in a state of forming a PVA-iodine complexAre present. By forming such a complex, absorption dichroism can be exhibited in the wavelength range of visible light. Specifically, a complex of PVA and triiodide ion (PVA. I)₃ ^-) A complex of PVA and a pentaiodide ion (PVA. I) having an absorption peak at about 470nm₅ ^-) Has an absorption peak around 600 nm. As a result, the polyiodide can absorb light in a wide range of visible light depending on its form. On the other hand, iodide ion (I)^-) Has an absorption peak near 230nm, and does not substantially participate in the absorption of visible light. Therefore, the polyiodide existing in a state of a complex with PVA can mainly participate in the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380nm to 780 nm. The monomer transmittance of the polarizer is preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

The value of b of the crossed hue of the polarizer is preferably-1.5 or less, more preferably-2.5 or less, as described above. The value b of the reflection hue of the polarizing plate (laminate of polarizer and protective layer described below) is preferably-1.5 or less, and more preferably-1.9 or less, as described above. When the b value and b x value are in such ranges, excellent hue can be achieved when the polarizing plate with a retardation layer is applied to an image display device. Further, the transmittance of the polarizing plate for light having a wavelength of 380nm is 5% or less, preferably 3% or less, and more preferably 2% or less, as described above.

B-2 protective layer

The protective layer 12 has a light transmittance at a wavelength of 380nm of 10% or less, preferably 9% or less, and more preferably 8.7% or less, as described above. The protective layer 12 has such a transmittance that ultraviolet light is extremely well blocked by the polarizing plate with a retardation layer. As a result, when the polarizing plate with a retardation layer is applied to an image display device, excellent weather resistance can be achieved.

The moisture permeability of the protective layer 12 is preferably 20g/m²24 hours or less, more preferably 15g/m²24 hours toIt is more preferably 12g/m²24 hours or less. If the moisture permeability of the protective layer is in such a range, the durability can be ensured even with a very thin polarizer as described above. As a result, the polarizing plate with a retardation layer has excellent durability, and the image display device can have extremely excellent weather resistance due to the synergistic effect of the excellent durability and the excellent ultraviolet absorbability.

As long as the protective layer 12 satisfies the above-described characteristics, any suitable configuration and material can be used. For example, the protective layer may be a single layer or may have a stacked structure. In one embodiment, the protective layer may be a single layer having ultraviolet absorbing ability. In another embodiment, the protective layer may be a laminate having an inner layer having ultraviolet absorbing ability and outer layers on both sides of the inner layer. Hereinafter, a case where the protective layer is the laminate will be described. The single layer may correspond to an inner layer of the stack.

As described above, the laminate has the inner layer and the outer layers on both sides of the inner layer. Typically, only the inner layer has uv absorbing capability. As the resin constituting the inner layer and the outer layer, any appropriate resin can be used. The cycloolefin resin is preferred. This is because the film has a desired moisture permeability when formed into a film, and does not adversely affect other characteristics even if ultraviolet absorbing ability is imparted.

The cycloolefin-based resin is a general term for a resin polymerized by using a cycloolefin as a polymerization unit, and examples thereof include resins described in Japanese patent laid-open Nos. 1-240517, 3-14882, and 3-122137. Specific examples thereof include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins and α -olefins such as ethylene and propylene, graft-modified products obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products of these. Specific examples of the cyclic olefin include a norbornene-based monomer. Examples of the norbornene-based monomer include norbornene and alkyl and/or alkylene substituted compounds thereof, and polar group substituted compounds such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene and 5-ethylidene-2-norbornene, and halogen and the like; dicyclopentadiene, 2, 3-dihydrodicyclopentadiene, and the like; methyl octahydronaphthalene, alkyl and/or alkylene substitutes thereof, and polar group substitutes such as halogen, for example, 6-methyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-ethyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-ethylene-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-chloro-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-cyano-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-pyridyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-methoxycarbonyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, etc.; trimer-tetramer of cyclopentadiene, for example, 4, 9: 5, 8-dimethylbridge-3 a,4,4a,5,8,8a,9,9 a-octahydro-1H-benzindene, 4, 11: 5,10: 6, 9-trimethyl-bridge-3 a,4,4a,5,5a,6,9,9a,10,10a,11,11 a-dodecahydro-1H-cyclopenta anthracene and the like.

In the present invention, other cycloolefins which can be ring-opening polymerized may be used in combination within a range not to impair the object of the present invention. Specific examples of such a cycloolefin include compounds having 1 reactive double bond such as cyclopentene, cyclooctene, and 5, 6-dihydrodicyclopentadiene.

The cyclic olefin resin preferably has a number average molecular weight (Mn) of 5000 to 200000, more preferably 8000 to 100000, still more preferably 10000 to 80000, and particularly 20000 to 50000, as measured by a Gel Permeation Chromatography (GPC) method using a toluene solvent. When the number average molecular weight is in the above range, a film having excellent mechanical strength and good solubility, moldability, and casting workability can be formed.

When the cycloolefin-based resin is obtained by hydrogenating a ring-opened polymer of a norbornene-based monomer, the hydrogenation ratio is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. Within such a range, the composition is excellent in resistance to thermal deterioration, resistance to photo deterioration, and the like.

As a method of imparting ultraviolet absorbing ability to the inner layer, any appropriate method can be employed. Typically, the ultraviolet absorbing ability is imparted by blending an ultraviolet absorber. As the ultraviolet absorber, any suitable ultraviolet absorber can be used. Specific examples thereof include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers and acrylonitrile-based ultraviolet absorbers. Preferred are 2,2 '-methylenebis (4- (1,1,3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2' -hydroxy-3 '-tert-butyl-5' -methylphenyl) -5-chlorobenzotriazole, 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2 '-dihydroxy-4, 4' -dimethoxybenzophenone, 2 ', 4, 4' -tetrahydroxybenzophenone. More preferably 2, 2' -methylenebis (4- (1,1,3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol). The content of the ultraviolet absorber in the inner layer is preferably 5 to 10 wt%, more preferably 6.5 to 9.5 wt%. When the content is in such a range, the transmittance of light having a wavelength of 380nm can be set to a desired range, and undesired coloring of the protective layer (and consequently the polarizing plate with a retardation layer) can be suppressed.

The thickness of the protective layer 12 is preferably 30 μm or less, and more preferably 25 μm or less, regardless of the single layer or the laminate. The lower limit of the thickness of the protective layer is, for example, 10 μm. According to the present invention, the durability of the polarizer can be ensured even though both the polarizer and the protective layer are very thin. As a result, the polarizing plate with a retardation layer (and consequently, the image display device) can be made remarkably thin and have excellent durability at the same time. When the surface treatment described below is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

The polarizing plate with a retardation layer of the present invention is typically disposed on the visual observation side of the image display device, and the protective layer 12 is typically disposed on the visual observation side, as described below. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coating treatment, antireflection treatment, anti-sticking treatment, and antiglare treatment as needed. Further, if necessary, the protective layer 12 may be subjected to a treatment for improving visibility in the case of visual confirmation through a polarizing sunglass (typically, a (elliptical) polarizing function is provided, and an ultrahigh phase difference is provided). By performing such processing, even when the display screen is visually confirmed through a polarizing lens such as a polarizing sunglass, excellent visual confirmation can be achieved. Therefore, the polarizing plate with a retardation layer can be suitably used also for an image display device usable outdoors.

C. 1 st phase difference layer

Characteristics of C-1. 1 st retardation layer

The 1 st retardation layer 20 may have any suitable optical and/or mechanical properties according to the purpose. The 1 st retardation layer 20 typically has a slow axis. In one embodiment, the angle θ formed by the slow axis of the 1 st retardation layer 20 and the absorption axis of the polarizer 11 is preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and still more preferably about 45 °. When the angle θ is in such a range, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (as a result, very excellent antireflection characteristics) can be obtained by setting the 1 st retardation layer to a λ/4 plate as described below.

The 1 st retardation layer preferably has a refractive index characteristic showing a relationship of nx > ny ≧ nz. The 1 st retardation layer is typically provided to impart antireflection characteristics to the polarizing plate, and in one embodiment, functions as a λ/4 plate. In this case, the in-plane retardation Re (550) of the 1 st retardation layer is preferably 80nm to 200nm, more preferably 100nm to 180nm, and still more preferably 110nm to 170 nm. Here, "ny ═ nz" includes not only the case where ny and nz are completely equal but also the case where ny and nz are substantially equal. Therefore, ny < nz may be used in some cases within a range not impairing the effects of the present invention.

The Nz coefficient of the 1 st 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 1 st retardation layer may exhibit reverse dispersion wavelength characteristics in which the phase difference value increases in accordance with the wavelength of the measurement light, may exhibit positive dispersion wavelength characteristics in which the phase difference value decreases in accordance with the wavelength of the measurement light, and may exhibit flat dispersion wavelength characteristics in which the phase difference value hardly changes depending on the wavelength of the measurement light. In one embodiment, the 1 st 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 to 0.95. With such a configuration, very excellent antireflection characteristics can be achieved.

The absolute value of photoelastic modulus contained in the 1 st phase difference layer is preferably 2X 10^-11m²A value of not more than N, more preferably 2.0X 10^-13m²/N～1.5×10^-11m²More preferably 1.0X 10^-12m²/N～1.2×10^-11m²A resin of/N. When the absolute value of the photoelastic modulus is in such a range, the retardation is less likely to change when a shrinkage stress occurs during heating. As a result, thermal unevenness of the obtained image display device can be prevented favorably.

C-2. the 1 st retardation layer composed of a resin film

When the 1 st retardation layer is formed of a resin film, the thickness thereof is preferably 60 μm or less, and preferably 30 to 55 μm. When the thickness of the 1 st retardation layer is in such a range, the curl at the time of heating can be favorably suppressed, and the curl at the time of bonding can be favorably adjusted.

The 1 st retardation layer 20 may be formed of any appropriate resin film that satisfies the characteristics described in the above item C-1. Representative examples of such resins include a cycloolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, a polyvinyl alcohol resin, a polyamide resin, a polyimide resin, a polyether resin, a polystyrene resin, and an acrylic resin. When the 1 st retardation layer is formed of a resin film exhibiting reverse dispersion wavelength characteristics, a polycarbonate-based resin can be suitably used.

As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained. The polycarbonate resin preferably contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of an alicyclic diol, an alicyclic dimethanol, diethylene glycol, triethylene glycol, or polyethylene glycol, and an alkylene glycol or a spiroglycol. Preferably, the polycarbonate resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol and/or a structural unit derived from diethylene glycol, triethylene glycol or polyethylene glycol; further preferably contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from diethylene glycol, triethylene glycol, or polyethylene glycol. The polycarbonate resin may contain a structural unit derived from another dihydroxy compound, if necessary. The details of the polycarbonate resin which can be suitably used in the present invention are described in, for example, japanese patent application laid-open nos. 2014-10291 and 2014-26266, which are incorporated herein by reference.

The glass transition temperature of the polycarbonate resin is preferably 110 to 150 ℃, more preferably 120 to 140 ℃. If the glass transition temperature is too low, heat resistance tends to be deteriorated, dimensional change may occur after film formation, and image quality of the obtained organic EL panel may be deteriorated. If the glass transition temperature is too high, the molding stability during film molding may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature is determined in accordance with JIS K7121 (1987).

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

A commercially available film may be used as the polycarbonate-based resin film. Specific examples of commercially available products include trade names "Pureace WR-S", "Pureace WR-W", "Pureace WR-M" manufactured by Didi, and trade name "NRF" manufactured by Nindon electric corporation.

The 1 st retardation layer 20 is obtained by, for example, stretching a film made of the above-mentioned polycarbonate resin. As a method for forming the film from the polycarbonate-based resin, any appropriate molding method can be employed. Specific examples thereof include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP (fiber reinforced Plastics) molding, casting coating (for example, casting), calendering, and hot press. Extrusion or cast coating is preferred. This is because the smoothness of the obtained film can be improved, and good optical uniformity can be obtained. The molding conditions may be appropriately set according to the composition and type of the resin used, the desired properties of the retardation layer, and the like. Since a large number of commercially available film products are available as described above, the commercially available film may be subjected to the stretching treatment as it is.

The thickness of the resin film (unstretched film) may be set to any appropriate value depending on the desired thickness of the 1 st retardation layer, desired optical properties, stretching conditions described below, and the like. Preferably 50 to 300. mu.m.

The stretching may be performed by any suitable stretching method and stretching conditions (e.g., stretching temperature, stretching ratio, and stretching direction). Specifically, various stretching methods such as free end stretching, fixed end stretching, free end shrinking, and fixed end shrinking may be used alone, or may be used simultaneously or stepwise. The stretching direction may be performed in various directions or dimensions such as a longitudinal direction, a width direction, a thickness direction, and an oblique direction. The stretching temperature is preferably from Tg-30 ℃ to Tg +60 ℃ and more preferably from Tg-10 ℃ to Tg +50 ℃ relative to the glass transition temperature (Tg) of the resin film.

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

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

In another embodiment, the retardation film may be produced by continuously obliquely stretching a long resin film in the direction of the angle θ with respect to the longitudinal direction. By employing oblique stretching, a long stretched film having an orientation angle of an angle θ (slow axis in the direction of the angle θ) with respect to the longitudinal direction of the film can be obtained, and for example, roll-to-roll can be realized when laminated with a polarizer, and the manufacturing process can be simplified. The angle θ may be an angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer in the polarizing plate with a retardation layer. As described above, the angle θ is preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and further preferably about 45 °.

As the stretching machine used for the oblique stretching, for example, a tenter type stretching machine capable of applying a feed force, a stretching force or a pulling force at different speeds in the lateral direction and/or the longitudinal direction can be cited. The tenter stretching machine includes a transverse uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine may be used as long as it can continuously stretch the long resin film obliquely.

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

The stretching temperature of the film may 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 magnification, and the like. Specifically, the stretching temperature is preferably from Tg-30 ℃ to Tg +30 ℃, more preferably from Tg-15 ℃ to Tg +15 ℃, and most preferably from Tg-10 ℃ to Tg +10 ℃. By stretching at such a temperature, the 1 st retardation layer having appropriate characteristics can be obtained in the present invention. The Tg is the glass transition temperature of the constituent material of the film.

C-3. the 1 st retardation layer composed of an alignment cured layer of a liquid crystal compound

The 1 st retardation layer 20 may be an alignment cured layer of a liquid crystal compound. Since the difference between nx and ny of the obtained retardation layer can be significantly increased as compared with a non-liquid crystal material by using a liquid crystal compound, the thickness of the retardation layer for obtaining a desired in-plane retardation can be significantly reduced. As a result, the polarizing plate with a retardation layer can be further thinned. When the 1 st retardation layer 20 is composed of an alignment cured layer of a liquid crystal compound, the thickness thereof is preferably 0.5 to 7 μm, more preferably 1 to 5 μm. By using the liquid crystal compound, an in-plane retardation equivalent to that of the resin film can be realized with a significantly smaller thickness than that of the resin film.

In the present specification, the "alignment cured layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. The "alignment cured layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer as described below. In the present embodiment, typically, the rod-like liquid crystal compound is aligned in a state of being aligned in the slow axis direction of the 1 st retardation layer (planar alignment). Examples of the liquid crystal compound include a liquid crystal compound having a nematic phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism of expression of the liquid crystallinity of the liquid crystal compound may be either of lyotropic or thermotropic properties. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., hardening) the liquid crystal monomer. After the liquid crystal monomers are aligned, for example, the alignment state can be fixed by polymerizing or crosslinking the liquid crystal monomers with each other. Here, the polymer is formed by polymerization and the three-dimensional network structure is formed by crosslinking, but they are non-liquid crystalline. Therefore, the 1 st retardation layer formed does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change, which is unique to a liquid crystalline compound, for example. As a result, the 1 st retardation layer is a retardation layer having extremely excellent stability without being affected by temperature change.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs depending on the type thereof. Specifically, the temperature range is preferably 40 to 120 ℃, more preferably 50 to 100 ℃, and most preferably 60 to 90 ℃.

As the liquid crystal monomer, any suitable liquid crystal monomer can be used. For example, the polymerizable mesogen compounds described in Japanese patent application laid-open No. 2002-533742(WO00/37585), EP358208(US5211877), EP66137(US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, GB2280445 and the like can be used, and specific examples of such polymerizable mesogen compounds include trade name LC242 by BASF, trade name E7 by Merck, and trade name LC-Sillicon-CC3767 by Wacker-Chem. The liquid crystal monomer is preferably, for example, a nematic liquid crystal monomer.

The alignment cured layer of the liquid crystal compound may be formed by: the method for producing a liquid crystal display device includes applying an alignment treatment to a surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface, aligning the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the aligned state. In one embodiment, the substrate is any suitable resin film, and the oriented cured layer formed on the substrate may be transferred to the surface of the polarizer 10. In another embodiment, the substrate may be the 2 nd protective layer 13. In this case, since the transfer step can be omitted and the alignment cured layer (1 st retardation layer) is formed and then laminated continuously by roll-to-roll, the productivity is further improved.

As the alignment treatment, any appropriate alignment treatment may be adopted. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment may be mentioned. Specific examples of the mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of the chemical alignment treatment include oblique vapor deposition and photo alignment treatment. The treatment conditions for the various alignment treatments may be any suitable conditions according to the purpose.

The alignment of the liquid crystal compound is performed by performing a treatment at a temperature at which the liquid crystal phase is exhibited according to the kind of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes a liquid crystal state, and the liquid crystal compound is aligned according to the alignment treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound after alignment as described above to polymerization treatment or crosslinking treatment.

Specific examples of the liquid crystal compound and the method for forming the alignment cured layer are described in japanese patent application laid-open No. 2006-163343. The description of this publication is incorporated herein by reference.

In an embodiment, the orientation cured layer may have a laminated structure of a 1 st orientation cured layer 21 and a 2 nd orientation cured layer 22 as shown in fig. 3. In this case, one of the 1 st orientation cured layer 21 and the 2 nd orientation cured layer 22 functions as a λ/4 plate, and the other functions as a λ/2 plate. Therefore, the thicknesses of the 1 st orientation-cured layer 21 and the 2 nd orientation-cured layer 22 can be adjusted so as to obtain a desired in-plane retardation of the λ/4 plate or the λ/2 plate. For example, when the 1 st orientation cured layer 21 functions as a λ/4 plate and the 2 nd orientation cured layer 22 functions as a λ/2 plate, the thickness of the 1 st orientation cured layer 21 is, for example, 0.5 μm to 2.5 μm, and the thickness of the 2 nd orientation cured layer 22 is, for example, 1.0 μm to 5.0 μm. The 1 st orientation cured layer 21 and the 2 nd orientation cured layer 22 may be stacked such that the slow axes thereof are at an angle of, for example, 50 ° to 70 °, preferably about 60 °. Further, the 1 st orientation cured layer 21 may be laminated such that the slow axis thereof is preferably about 15 ° from the absorption axis of the polarizer 11, and the 2 nd orientation cured layer 22 may be laminated such that the slow axis thereof is preferably about 75 ° from the absorption axis of the polarizer 11. With such a configuration, a characteristic close to an ideal reverse wavelength dispersion characteristic can be obtained, and as a result, a very excellent antireflection characteristic can be realized.

D. Adhesive layer

The light transmittance of the pressure-sensitive adhesive layer 30 at a wavelength of 405nm is 5% or less, preferably 3% or less, and more preferably 1% or less, as described above. By the adhesive layer 30 having such a transmittance, ultraviolet light is extremely well blocked by the polarizing plate with a retardation layer. As a result, when the polarizing plate with a retardation layer is applied to an image display device, excellent weather resistance can be achieved. Further, by containing an ultraviolet absorber in the protective layer, the pressure-sensitive adhesive layer can be ensured in weather resistance by the ultraviolet absorbing function, and very excellent weather resistance as an image display device can be achieved.

Further, the adhesive layer 30 has the following light transmittance: the average transmittance at a wavelength of 300nm to 400nm is preferably 5% or less, more preferably 2% or less; the average transmittance at a wavelength of 400nm to 430nm is preferably 30% or less, more preferably 20% or less; the average transmittance at a wavelength of 450nm to 500nm is preferably 70% or more, more preferably 75% or more; the average transmittance at a wavelength of 500nm to 780nm is preferably 80% or more, more preferably 85% or more. When the average transmittance of 300nm to 430nm is in the above range, light which does not contribute to image display and may cause deterioration of the image display device can be favorably cut off. When the average transmittance of 450nm to 780nm is in the above range, light contributing to image display (for example, light emitted from an organic EL cell) can be favorably transmitted. For example, the "average transmittance at a wavelength of 300 to 400 nm" means an average value of the transmittances calculated at a pitch of 1nm in the wavelength region.

The haze value of the pressure-sensitive adhesive layer 30 measured with a thickness of 25 μm is preferably 2.0% or less, more preferably 1.5% or less, and still more preferably 1.0% or less. The lower the haze value, the lower the haze value is, for example, 0%. When the haze value is in such a range, a polarizing plate with a retardation layer having sufficient transparency can be obtained, and as a result, an image display device having excellent visibility can be obtained.

As the adhesive (adhesive composition) constituting the adhesive layer 30, an adhesive having any appropriate structure that can satisfy the above-described characteristics can be used. The adhesive agent typically contains a base polymer, an ultraviolet absorber, and a pigment compound having an absorption spectrum whose maximum absorption wavelength is present in a wavelength region of 380nm to 430 nm. Here, the maximum absorption wavelength refers to an absorption maximum wavelength at which the maximum absorbance is exhibited when a plurality of absorption maxima are present in the spectral absorption spectrum in the wavelength region of 300nm to 460 nm.

As the base polymer, any suitable polymer may be used. The (meth) acrylic polymer is preferable. This is because the optical transparency is excellent, the adhesive exhibits appropriate adhesive properties (for example, a balance between adhesiveness, cohesiveness, and adhesiveness), and the weather resistance and heat resistance are excellent. The (meth) acrylic polymer has a constituent unit derived from an alkyl (meth) acrylate as a main constituent unit constituting the skeleton. Examples of the alkyl (meth) acrylate include C1 to C20 alkyl (meth) acrylates. The alkyl (meth) acrylate preferably has a linear or branched alkyl group having from C4 to C18. The content ratio of the structural unit derived from the alkyl (meth) acrylate is preferably 60 parts by weight or more, and more preferably 80 parts by weight or more, based on 100 parts by weight of the base polymer.

The base polymer may contain a constituent unit derived from another monomer component copolymerizable with the alkyl (meth) acrylate, if necessary. Examples of such monomer components (copolymerization components) include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; vinyl monomers such as N-vinyl-2-pyrrolidone; anhydride monomers such as maleic anhydride and itaconic anhydride; sulfonic acid group-containing monomers such as styrenesulfonic acid and allylsulfonic acid; aromatic ring-containing alkyl (meth) acrylates such as phenoxyethyl (meth) acrylate and benzyl (meth) acrylate; (N-substituted) amide monomers such as (meth) acrylamide and N, N-dimethyl (meth) acrylamide; alkylaminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate and N, N-dimethylaminoethyl (meth) acrylate; alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; succinimide monomers such as N- (meth) acryloyloxymethylene succinimide and N-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide; and itaconimide monomers such as N-methylitaconimide. Further, vinyl monomers, cyanoacrylate monomers, epoxy group-containing acrylic monomers, glycol-based acryl monomers, silane-based monomers, isoprene, butadiene, isobutylene, vinyl ether and the like can be used as the copolymerization component. Further, polyfunctional acrylates such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and hexanediol di (meth) acrylate may also be used as the copolymerization component. By adjusting the kind, combination, and blending ratio of the copolymerization components (as a result, the content ratio of the constituent units), a binder having desired characteristics can be obtained.

The weight average molecular weight of the base polymer is preferably 80 to 300 ten thousand, more preferably 100 to 250 ten thousand, and further preferably 140 to 200 ten thousand. Within such a range, an adhesive layer exhibiting an appropriate amount of creep can be formed. The weight average molecular weight is determined from a value calculated by measuring by GPC (gel permeation chromatography; solvent: THF (Tetrahydrofuran)) and converting into polystyrene.

Examples of the ultraviolet absorber include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, hydroxybenzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. The ultraviolet absorber may be used alone or in combination of two or more. Preferred are triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers. More preferably, the ultraviolet absorber is a triazine-based ultraviolet absorber having 2 or less hydroxyl groups in one molecule, or a benzotriazole-based ultraviolet absorber having 1 benzotriazole skeleton in one molecule. This is because they have good solubility in monomers constituting the base polymer and high ultraviolet absorbability at a wavelength of about 380 nm.

Specific examples of triazine-based ultraviolet absorbers having 2 or less hydroxyl groups in one molecule include 2, 4-bis- [ {4- (4-ethylhexyloxy) -4-hydroxy } -phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine (tinosorb s, manufactured by BASF), 2, 4-bis [ 2-hydroxy-4-butoxyphenyl ] -6- (2, 4-dibutoxyphenyl) -1,3, 5-triazine (TINUVIN460, manufactured by BASF), a reaction product of 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl and [ (C10-C16 (mainly C12-C13) alkoxy) methyl ] ethylene oxide (TINUVIN400, manufactured by BASF), 2- [4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl ] -5- [3- (dodecyloxy) -2-hydroxypropoxy ] phenol), the reaction product of 2- (2, 4-dihydroxyphenyl) -4, 6-bis- (2, 4-dimethylphenyl) -1,3, 5-triazine with (2-ethylhexyl) -glycidic acid ester (TINUVIN405, manufactured by BASF), 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol (TINUVIN1577, manufactured by BASF), 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy ] -phenol (ADK STAB LA46, manufactured by ADEKA), 2- (2-hydroxy-4- [ 1-octyloxycarbonylethoxy ] phenyl) -4, 6-bis (4-phenylphenyl) -1,3, 5-triazine (TINUVIN479, manufactured by BASF).

Specific examples of the benzotriazole-based ultraviolet absorber having 1 benzotriazole skeleton in one molecule include 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN928, manufactured by BASF), 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (TINUVIN PS, manufactured by BASF), an ester compound of phenylpropionic acid and 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy (C7-9 side chain and straight chain alkyl) (TINUVIN384-2, manufactured by BASF), and 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN900, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN928, manufactured by BASF), a reaction product of methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate/polyethylene glycol 300 (TINUVIN1130, manufactured by BASF), 2- (2H-benzotriazol-2-yl) P-cresol (TINUVIN P, manufactured by BASF), 2 (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN234, BASF), 2- [ 5-chloro (2H) -benzotriazol-2-yl ] -4-methyl-6- (tert-butyl) phenol (TINUVIN326, BASF), 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-amylphenol (TINUVIN328, BASF), the reaction product of methyl 2- (2H-benzotriazol-2-yl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN329, BASF), 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate with polyethylene glycol 300 (TINUVIN213, BASF), 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (TINUVIN571, BASF), 2- [ 2-hydroxy-3- (3,4,5, 6-tetrahydrophthalimido-methyl) -5-methylphenyl ] benzotriazole (sumiosorb 250, manufactured by sumitomo chemical industries, ltd.).

The maximum absorption wavelength of the absorption spectrum of the ultraviolet absorber is preferably in the wavelength region of 300 to 400nm, more preferably in the wavelength region of 320 to 380 nm.

The content of the ultraviolet absorber in the pressure-sensitive adhesive layer is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the base polymer. When the content of the ultraviolet absorber is in such a range, the ultraviolet absorbing ability of the pressure-sensitive adhesive layer can be made sufficient.

As described above, the absorption spectrum of the dye compound has a maximum absorption wavelength in the wavelength region of 380nm to 430nm, preferably 380nm to 420 nm. When such a dye compound is used in combination with the ultraviolet absorber, the effect is particularly remarkable when the polarizing plate with a retardation layer is used in an organic EL display device. Specifically, since light in a region (wavelength 380nm to 430nm) that does not affect light emission of the organic EL unit can be sufficiently absorbed and a light-emitting region (longer wavelength side than 430nm) of the organic EL unit can be sufficiently transmitted, it is possible to suppress deterioration due to external light while maintaining good light-emitting characteristics of the organic EL display device. The half-value width of the peak of the dye compound at the maximum absorption wavelength is preferably 80nm or less, more preferably 5nm to 70nm, and still more preferably 10nm to 60 nm. The half-value width can be determined using a spectrophotometer.

As the dye compound, any appropriate dye compound that can have the above-described characteristics can be used. For example, the dye compound may be an organic dye compound or an inorganic dye compound. The organic dye compound is preferred. This is because the polymer is excellent in dispersibility and transparency in the base polymer. Specific examples of the organic dye compound include an azomethine compound, an indole compound, a cinnamic acid compound, and a porphyrin compound. Commercially available dye compounds may be used. Specifically, the indole compound includes BONASORB UA3911 (trade name, maximum absorption wavelength of absorption spectrum: 398nm, half width: 48nm, manufactured by Orient Chemical Industries, Ltd.), BONASORB UA3912 (trade name, maximum absorption wavelength of absorption spectrum: 386nm, half width: 53nm, manufactured by Orient Chemical Industries, Ltd.). The cinnamic acid-based compound may be SOM-5-0106 (trade name: maximum absorption wavelength of absorption spectrum: 416nm, half-value width: 50nm, manufactured by Orient chemical industries, Ltd.). Examples of the porphyrin-based compound include FDB-001 (trade name, maximum absorption wavelength of absorption spectrum: 420nm, half-value width: 14nm, manufactured by Hill-Takara chemical Co., Ltd.). The pigment compounds may be used alone or in combination of two or more.

The content of the pigment compound in the pressure-sensitive adhesive layer is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 5 parts by weight, based on 100 parts by weight of the base polymer. When the content of the dye compound is in such a range, the effect becomes remarkable particularly in the case where a polarizing plate with a retardation layer is used in an organic EL display device. Specifically, light in a region that does not affect light emission of the organic EL unit can be absorbed more favorably. As a result, deterioration of the organic EL display device due to external light can be further favorably suppressed.

The adhesive (adhesive composition) may also further comprise any suitable additive. Specific examples of the additives include silane coupling agents, crosslinking agents, adhesion imparting agents, plasticizers, pigments, dyes, fillers, antioxidants, age resistors, conductive materials, light stabilizers, release control agents, softening agents, surfactants, flame retardants, and polymerization initiators. The kind, combination, blending amount and the like of the additives can be appropriately set according to the purpose.

The thickness of the pressure-sensitive adhesive layer is preferably 50 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. The lower limit of the thickness of the adhesive layer is, for example, 10 μm. When the thickness of the pressure-sensitive adhesive layer is within such a range, there is an advantage that both thinning, adhesiveness, and adhesion durability can be achieved.

E. Phase difference layer 2

The 2 nd retardation layer 40 may have any suitable optical characteristics according to purposes. In one embodiment, the 2 nd retardation layer may be a so-called positive C plate having a refractive index characteristic showing a relationship of nz > nx ═ ny. By using the positive C plate as the 2 nd retardation layer, reflection in an oblique direction can be prevented well, and a wide viewing angle of the antireflection function can be realized. In this case, the retardation Rth (550) in the thickness direction of the 2 nd retardation layer is preferably from-50 nm to-300 nm, more preferably from-70 nm to-250 nm, still more preferably from-90 nm to-200 nm, and particularly preferably from-100 nm to-180 nm. Here, "nx ═ ny" includes not only a case where nx and ny are strictly equal but also a case where nx and ny are substantially equal. That is, the in-plane retardation Re (550) of the 2 nd retardation layer may be less than 10 nm.

The 2 nd retardation layer having a refractive index characteristic of nz > nx ═ ny may be formed of any suitable material. The 2 nd phase difference layer is preferably made of a film containing a liquid crystal material fixed to a vertical orientation. The liquid crystal material (liquid crystal compound) capable of vertical alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compounds and the methods for forming the retardation layer described in [0020] to [0028] of Japanese patent laid-open publication No. 2002-333642. In this case, the thickness of the 2 nd retardation layer is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and still more preferably 0.5 to 5 μm.

F. Conductive layer or isotropic substrate with conductive layer

The conductive layer can be formed by forming a metal oxide film on any suitable substrate by any suitable film forming method (for example, vacuum Deposition, sputtering, CVD (chemical vapor Deposition), ion plating, spraying, or the like). Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferable.

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

The conductive layer may be transferred from the substrate to the 1 st retardation layer (or the 2 nd retardation layer if present) and used alone as a constituent layer of the polarizing plate with a retardation layer, or may be laminated on the 1 st retardation layer (or the 2 nd retardation layer if present) as a laminate with the substrate (substrate with a conductive layer). The substrate is preferably optically isotropic, and therefore, the conductive layer can be used as an isotropic substrate with a conductive layer for a polarizing plate with a retardation layer.

As the optically isotropic substrate (isotropic substrate), any appropriate isotropic substrate can be used. Examples of the material constituting the isotropic base include a material having a resin not having a conjugate system such as a norbornene-based resin or an olefin-based resin as a main skeleton, and a material having a cyclic structure such as a lactone ring or a glutarimide ring in a main chain of an acrylic resin. When such a material is used, the expression of retardation accompanying the orientation of the molecular chains can be suppressed to a small extent when forming an isotropic base material. The thickness of the isotropic base material is preferably 50 μm or less, more preferably 35 μm or less. The lower limit of the thickness of the isotropic base material is, for example, 20 μm.

The conductive layer of the conductive layer and/or the conductive layer of the isotropic substrate with a conductive layer may be patterned as necessary. By patterning, the conductive portion and the insulating portion can be formed. As a result, an electrode can be formed. The electrodes may function as touch sensor electrodes that sense contact with the touch panel. As the patterning method, any appropriate method can be employed. Specific examples of the patterning method include a wet etching method and a screen printing method.

G. Others

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

H. Image display device

The polarizing plate with a retardation layer described in the above items A to G can be applied to an image display device. Accordingly, the present invention includes an image display device using such a polarizing plate with a retardation layer. As typical examples of the image display device, a liquid crystal display device and an organic EL display device can be given. An image display device according to an embodiment of the present invention includes the polarizing plate with a retardation layer described in the above items a to G on a visual confirmation side. The polarizing plates with a retardation layer are laminated such that the retardation layer is on the display cell (for example, liquid crystal cell or organic EL cell) (such that the polarizer is on the visual side).