CN116953839A

CN116953839A - Polarizing plate with retardation layer and image display device

Info

Publication number: CN116953839A
Application number: CN202310462392.2A
Authority: CN
Inventors: 三田聪司; 有贺草平; 笹川泰介
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2022-04-27
Filing date: 2023-04-26
Publication date: 2023-10-27
Also published as: KR20230152587A; TW202343043A; JP2023162732A

Abstract

Provided is a polarizing plate with a retardation layer and an image display device. The polarizing plate with the retardation layer contributes to providing an image display device having excellent durability even under severe high-temperature and high-humidity environments. The polarizing plate comprises a first retardation layer having a first main surface and a second main surface opposite to each other, a polarizing material arranged on the first main surface side of the first retardation layer, a first resin layer arranged on the second main surface side of the first retardation layer, and a second resin layer arranged between the polarizing material and the first retardation layer, wherein the first retardation layer is composed of a stretched film of a resin film and satisfies 450)<Re (550) relationship, the storage modulus of the first resin layer at 100℃was 1.0X10 ⁶ Pa or more, the second resin layer has a thickness of 1 μm or less and contains a resin and an isocyanate compound, and Re (450) and Re (550) are in-plane phase differences measured at 23 ℃ by light having a wavelength of 450nm and a wavelength of 550nm, respectively.

Description

Polarizing plate with retardation layer and image display device

Technical Field

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

Background

In recent years, image display devices represented by liquid crystal display devices and Electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) are rapidly spreading. Typically, a polarizing plate and a retardation plate are used in the image display device. In practical use, a polarizing plate with a retardation layer, which is formed by integrating a polarizing plate and a retardation plate, is widely used (for example, patent document 1). In recent years, with the expansion of applications of image display devices, durability under severe high-temperature and high-humidity environments, which has not been conventionally required, is sometimes required.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 3325560

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described conventional problems, and has as its main object to provide a polarizing plate with a retardation layer which contributes to providing an image display device having excellent durability even in a severe high-temperature and high-humidity environment.

Solution for solving the problem

1. The polarizing plate with a retardation layer according to an embodiment of the present invention includes: a first phase difference layer having a first main surface and a second main surface facing each other; a polarizer disposed on the first principal surface side of the first retardation layer; a first resin layer disposed on the second principal surface side of the first retardation layer; and a second resin layer disposed between the polarizer and the first retardation layer, wherein the first retardation layer is formed of a stretched film of a resin film and satisfies Re (450)<Re (550), the storage modulus of the first resin layer at 100 ℃ is 1.0X10 ⁶ Pa or more, the second resin layer having a thickness of 1 μm or less and comprising a resin and an isocyanate compound, wherein Re (450) and Re (550) is the in-plane retardation measured at 23℃by light of wavelength 450nm and light of wavelength 550nm, respectively.

2. The polarizing plate with a retardation layer according to the above 1 may have an adhesive layer disposed between the first retardation layer and the polarizing element and adjacent to the second resin layer, wherein the adhesive layer is composed of a cured layer of an adhesive composition, and an octanol/water distribution coefficient log pow calculated by a weighted average of mole fractions of monomer components contained in the adhesive composition may be 1.5 to 4.0.

3. The polarizing plate with a retardation layer according to the above 1 or 2, wherein the second resin layer may contain a resin having a glass transition temperature of 85 ℃ or higher and a weight average molecular weight Mw of 50000 or higher and less than 500000, and the content of the resin in the second resin layer may be 50% by weight or more and 90% by weight or less.

4. The polarizing plate with a retardation layer according to any one of the above 1 to 3, wherein the isocyanate compound contained in the second resin layer may contain at least 1 selected from toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives thereof, and the content of the isocyanate compound in the second resin layer may be 10% by weight or more and 50% by weight or less.

5. The polarizing plate with a retardation layer according to any one of the above 1 to 4 may have a second retardation layer disposed on the second principal surface side of the first retardation layer, wherein refractive index characteristics show a relationship of nz > nx=ny, and the first resin layer may be disposed between the first retardation layer and the second retardation layer.

6. The polarizing plate with a retardation layer according to claim 5, wherein the first resin layer functions as an adhesive layer.

7. The polarizing plate with a retardation layer as claimed in any one of the above 1 to 6, wherein the first resin layer has a storage modulus at 100℃of 1.0X10 ⁸ Pa or more.

8. The tape according to any one of the above 1 to 7In the polarizing plate of the retardation layer, the first resin layer may have a storage modulus of 1.0X10 at 25 DEG C ⁹ Pa or more.

9. In the polarizing plate with a retardation layer according to any one of the above 1 to 8, the ratio (G '(25)/G' (100)) of the storage modulus G '(25) at 25 ℃ to the storage modulus G' (100) at 100 ℃ of the first resin layer may be less than 10.0.

10. In the polarizing plate with a retardation layer according to any one of the above 1 to 9, the first retardation layer may contain a resin which contains at least 1 kind of bonding group selected from the group consisting of a carbonate bond and an ester bond and at least 1 kind of structural unit selected from the group consisting of a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II), and has positive refractive index anisotropy:

In the general formulae (I) and (II), R ¹ ～R ³ Each independently is a direct bond, substituted or unsubstituted alkylene group of 1 to 4 carbon atoms, R ⁴ ～R ⁹ Each independently is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a halogen atom, a nitro group, or a cyano group, wherein R ⁴ ～R ⁹ Optionally identical or different from each other, R ⁴ ～R ⁹ Optionally bonded to each other to form a ring.

11. An image display device according to an embodiment of the present invention includes the polarizing plate with a retardation layer described in any one of 1 to 10.

ADVANTAGEOUS EFFECTS OF INVENTION

With the embodiments of the present invention, a polarizing plate with a retardation layer can be realized, which can contribute to providing an image display device having excellent durability even under severe high-temperature and high-humidity environments.

Drawings

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

Fig. 2 is a schematic cross-sectional view showing a schematic configuration of an image display panel according to 1 embodiment of the present invention.

Description of the reference numerals

10. Polarizing plate

11. Polarizing element

12. Protective layer

21. First phase difference layer

22. Second phase difference layer

30. A first resin layer

50. Second resin layer

60. Adhesive layer

100 polarizing plate with phase difference layer

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The drawings are for clarity of description, and therefore, width, thickness, shape, and the like of each portion are schematically shown in comparison with the embodiment, but are merely examples, and do not limit the explanation of the present invention.

(definition of terms 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 refractive index in the plane 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 phase difference (Re)

"Re (λ)" is the in-plane retardation of a film measured at 23℃using light of wavelength λnm. For example, "Re (450)" is the in-plane retardation of a film measured at 23℃using light having a wavelength of 450 nm. When the thickness of the film is d (nm) for Re (λ), the formula: re= (nx-ny) x d.

(3) Retardation in thickness direction (Rth)

"Rth (λ)" is the retardation in the thickness direction of the film measured at 23℃by light having a wavelength of λnm. For example, "Rth (450)" is the retardation in the thickness direction of the film measured at 23℃by light having a wavelength of 450 nm. When the thickness of the thin film is d (nm) for Rth (λ), the formula: rth= (nx-nz) ×d.

(4) Nz coefficient

The Nz coefficient is obtained by nz=rth/Re.

(5) Angle of

In the present specification, when referring to an angle, unless otherwise specified, the angle includes angles in both the clockwise direction and the counterclockwise direction.

A. Polarizing plate with phase difference layer

Fig. 1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate with a retardation layer according to 1 embodiment of the present invention. The polarizing plate 100 with a retardation layer includes: the polarizing plate comprises a first retardation layer 21 having a first main surface 21a and a second main surface 21b facing each other, a polarizing plate 10, a second resin layer 50 and an adhesive layer 60 disposed on the first main surface 21a side of the first retardation layer 21, and a first resin layer 30, a second retardation layer 22 and an adhesive layer 40 disposed on the second main surface 21b side of the first retardation layer 21. The polarizing plate 10 includes a polarizer 11 and a protective layer 12 in this order from the first retardation layer 21 side. The protective layer is not disposed between the polarizer 11 and the first retardation layer 21, and the second resin layer 50 is disposed adjacent to the polarizer 11 and functions as a protective material for the polarizer 11. The polarizing plate 100 with a retardation layer is typically disposed in the image display device such that the polarizer 11 is on the visual recognition side compared to the first retardation layer 21. The polarizing plate 100 with a retardation layer can be obtained by laminating the polarizing plate 10 obtained by laminating the polarizer 11 and the protective layer 12 with other layers, for example.

In the example shown in the figure, the polarizing plate 10 includes a polarizer 11 and a protective layer 12 disposed on one side of the polarizer 11, and may further include a second protective layer disposed on the other side of the polarizer 11. The polarizing plate 10 includes the polarizer 11 and the protective layer 12, but the protective layer 12 may be omitted.

The second resin layer 50 may reduce the influence (may have a blocking function) that the polarizer 11 may have on other members. For example, the movement of iodine that can be contained in the polarizer can be suppressed, and when the polarizing plate with the retardation layer is mounted on an image display device, corrosion of a metal member of the image display device can be significantly suppressed. The polarizing plate 100 with a retardation layer may further have such a resin layer (for example, a third resin layer disposed between the second retardation layer 22 and the adhesive layer 40).

The first retardation layer 21 is made of a stretched film of a resin film, and satisfies the relationship Re (450) < Re (550). Re (550) of the first retardation layer 21 is typically 100nm to 200nm. The angle between the slow axis of the first retardation layer 21 and the absorption axis of the polarizer 11 is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, still more preferably 44 ° to 46 °, and particularly preferably about 45 °; alternatively, it is preferably 130 ° to 140 °, more preferably 132 ° to 138 °, further preferably 134 ° to 136 °, and particularly preferably about 135 °.

The respective members constituting the polarizing plate with the retardation layer may be laminated via any appropriate adhesive layer. Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. The first retardation layer 21 is laminated on the second resin layer 50 via the adhesive layer 60. The adhesive layer 60 may be an adhesive layer (for example, an acrylic adhesive layer) or an adhesive layer. In the case of the pressure-sensitive adhesive layer, the thickness thereof is preferably 5 μm to 10 μm. By providing the adhesive layer, the thickness of the adhesive layer can be made extremely thin (for example, less than 5 μm), which can greatly contribute to the thinning of the polarizing plate with the retardation layer. Although not shown, the protective layer 12 is bonded to the polarizer 11 via an adhesive layer (preferably, an active energy ray-curable adhesive) for example. The thickness of the adhesive layer is, for example, 0.05 μm or more, preferably 0.4 μm to 3.0 μm, more preferably 0.6 μm to 2.2 μm.

The polarizing plate 100 with a retardation layer can be attached to an image display panel included in an image display device, for example, by the pressure-sensitive adhesive layer 40 disposed on the second main surface 21b side of the first retardation layer 21. The thickness of the adhesive layer 40 is preferably 10 μm to 20 μm. The adhesive layer 40 is made of, for example, an acrylic adhesive. Although not shown, in practice, a release liner is attached to the surface of the adhesive layer 40. The release liner may be temporarily adhered until the polarizing plate with the retardation layer is provided before use. By using a release liner, for example, the adhesive layer 40 can be protected, and a roll of the polarizing plate with a retardation layer can be formed.

The first resin layer 30 may be a cured layer of resin, a solidified layer of resin, or a layer formed by a combination thereof. The first resin layer 30 is preferably disposed in direct contact with the first retardation layer 21 (formed directly on the first retardation layer 21). In embodiment 1, the first resin layer 30 may function as an adhesive layer for fixing the first retardation layer 21 and the second retardation layer 22 to each other.

The storage modulus G' (100) of the first resin layer 30 at 100℃was 1.0X10 ⁶ Pa or more, preferably 1.0X10 ⁸ Pa or more, more preferably 3.0X10 ⁸ Pa or more. On the other hand, the storage modulus G' (100) of the first resin layer 30 at 100℃is preferably 1.0X10 ¹⁰ Pa or below.

The storage modulus G' (25) of the first resin layer 30 at 25℃is preferably 1.0X10 ⁶ Pa or more, more preferably 1.0X10 ⁹ Pa or more, and more preferably 1.5X10 ⁹ Pa or more. On the other hand, the storage modulus G' (25) of the first resin layer 30 at 25℃is preferably 1.0X10 ¹⁰ Pa or below. The ratio (G '(25)/G' (100)) of the storage modulus G '(25) at 25 ℃ to the storage modulus G' (100) at 100 ℃ of the first resin layer 30 is preferably greater than 1.0, more preferably 3.0 or more. On the other hand, G '(25)/G' (100) is preferably less than 10.0, more preferably 8.0 or less.

By providing the first resin layer, a polarizing plate with a retardation layer having excellent durability even in a severe high-temperature and high-humidity environment can be realized. Specifically, a polarizing plate with a retardation layer that can suppress cracking and peeling even in a severe high-temperature and high-humidity environment can be realized. Details are as follows. The first retardation layer used in the embodiment of the present invention exhibits a very excellent circular polarization characteristic, and thus a polarizing plate (circular polarizing plate) with a retardation layer having a very excellent antireflection function can be realized. Further, such a first retardation layer can be used in combination with a second retardation layer having refractive index characteristics described below, which show a relationship of nz > nx=ny, whereby the antireflection function can be made wide in viewing angle. On the other hand, since the stretched film of the resin film constituting the first retardation layer has a large heat shrinkage and a high water absorption rate, the reliability in a high-temperature and high-humidity environment may be insufficient, and further, cracks and/or peeling may occur in a severe high-temperature and high-humidity environment which gradually becomes a new standard in recent years regarding characteristics. By providing the first resin layer according to the embodiment of the present invention, durability and reliability in a severe high-temperature and high-humidity environment can be significantly improved as a whole of the polarizing plate with the retardation layer while maintaining excellent characteristics of the first retardation layer. As a result, a polarizing plate with a retardation layer that can suppress cracking and peeling even in a severe high-temperature and high-humidity environment can be realized. In addition, by using the first resin layer and the second resin layer in combination, an image display device having extremely excellent durability can be provided. The above mechanism is presumed, and the mechanism does not limit or restrict the embodiment of the present invention.

The refractive index characteristics of the second phase difference layer 22 that can be included in the polarizing plate with a phase difference layer typically show a relationship of nz > nx=ny. By providing such a retardation layer, reflection in an oblique direction can be satisfactorily prevented, and a wide viewing angle of an antireflection function can be achieved.

The polarizing plate with a retardation layer may further have a retardation layer (not shown). The optical characteristics (for example, refractive index characteristics, in-plane retardation, nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the further retardation layer can be appropriately set according to the purpose.

The polarizing plate with the retardation layer may be sheet-shaped or strip-shaped. The term "strip-like" as used herein refers to an elongated shape having a length sufficiently long with respect to the width, and includes, for example, an elongated shape having a length of 10 times or more, preferably 20 times or more, with respect to the width. The strip-shaped polarizing plate with the retardation layer may be wound into a roll.

B. Polarizing element

As the polarizer 11, any suitable polarizer may be used. For example, the polarizing element may be made of a single-layer resin film, or may be made of a laminate of two or more layers.

Specific examples of the polarizing material comprising a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, and an ethylene/vinyl acetate copolymer partially saponified film, which is obtained by dyeing and stretching a dichroic material such as iodine or a dichroic dye, a dehydrated PVA product, and a multi-functional oriented film such as a desalted polyvinyl chloride product. In view of excellent optical characteristics, a polarizing material obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is preferably used.

The iodine-based dyeing is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the unidirectional stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment or may be performed while dyeing. Alternatively, the stretching may be followed by dyeing. If necessary, the PVA-based film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like. For example, by immersing the PVA-based film in water before dyeing and washing with water, not only stains and anti-blocking agents on the surface of the PVA-based film can be washed, but also the PVA-based film can be swelled to prevent uneven dyeing.

Specific examples of the polarizing material obtained by using the laminate of two or more layers include: a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed on the resin base material by coating. A polarizing material obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, as follows: coating a PVA-based resin solution on a resin substrate, drying the resin substrate to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate was stretched and dyed, and the PVA-based resin layer was formed into a polarizing element. In the present embodiment, it is preferable to form a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution to stretch the laminate. Further, stretching may further include, if necessary, subjecting the laminate to air stretching at a high temperature (for example, 95 ℃ or higher) before stretching in an aqueous boric acid solution. In the present embodiment, it is preferable that the laminate be subjected to a drying shrinkage process in which the laminate is heated while being conveyed in the longitudinal direction, whereby the laminate is shrunk by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes sequentially subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, an in-water stretching treatment, and a drying shrinkage treatment. By introducing the auxiliary stretching, even when PVA is coated on the thermoplastic resin, crystallinity of PVA can be improved, and high optical characteristics can be achieved. Further, by simultaneously improving the orientation of PVA in advance, problems such as lowering of the orientation and dissolution of PVA can be prevented when immersed in water in the subsequent dyeing step and stretching step, and high optical characteristics can be achieved. Further, when the PVA-based resin layer is immersed in a liquid, disturbance of orientation of polyvinyl alcohol molecules and reduction of orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. Thus, the optical characteristics of the polarizer obtained by the treatment step of immersing the laminate in a liquid, such as dyeing treatment and stretching treatment in water, are improved. Further, by shrinking the laminate in the width direction by the drying shrinkage treatment, the optical characteristics can be improved. The resulting laminate of the resin substrate and the polarizing element may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizing element), or may be used as a release surface for releasing the resin substrate from the laminate of the resin substrate and the polarizing element, or may be used by laminating any appropriate protective layer suitable for the purpose on a surface opposite to the release surface. Details of such a method for producing a polarizing material are described in, for example, japanese patent application laid-open No. 2012-73580 and japanese patent No. 6470455. The entire disclosures of these publications are incorporated herein by reference.

The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, further preferably 10 μm or less, particularly preferably 8 μm or less, and particularly preferably 5 μm or less. The lower limit of the thickness of the polarizer may be, for example, 1 μm. When the thickness of the polarizing material is in such a range, curling at the time of heating can be satisfactorily suppressed, and excellent durability of appearance at the time of heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any of wavelengths 380nm to 780 nm. The monomer transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

C. Protective layer

The protective layer 12 and the second protective layer, not shown, are each formed of any appropriate thin film that can be used as a protective layer for a polarizing element. Specific examples of the material as the main component of the film include cellulose resins such as Triacetylcellulose (TAC), transparent resins such as polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, cyclic olefin resins (for example, polynorbornene resins), polyolefin resins, (meth) acrylic resins, and acetate resins. Further, a (meth) acrylic resin, a urethane resin, a (meth) acrylic urethane resin, an epoxy resin, a silicone resin, or other thermosetting resin, ultraviolet curable resin, or the like can be mentioned. Further, for example, a vitreous polymer such as a siloxane polymer can be used. In addition, a polymer film described in Japanese patent application laid-open No. 2001-343529 (WO 01/37007) can also be used. As a material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain, and for example, a resin composition having an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be used. The polymer film may be, for example, an extrusion molded product of the above resin composition.

The shrinkage of the protective layer 12 after being left at 85 ℃ for 240 hours is preferably less than 0.05%, more preferably 0.04% or less, and still more preferably 0.03% or less. The lower limit of the shrinkage ratio may be, for example, 0.01%, as the shrinkage ratio is smaller. When the shrinkage ratio is in such a range, cracks of the polarizer and peeling of the polarizer and the retardation layer in a severe high-temperature and high-humidity environment can be more favorably suppressed. The protective layer 12 is preferably composed of a cellulose Triacetate (TAC) film or a cycloolefin resin film. The TAC film and the cycloolefin resin film are preferably formed by extrusion or casting (cast), and stretching is not involved in the film formation. As a result, the residual stress is small, and thus the above-described desired shrinkage rate can be achieved.

The polarizing plate with a retardation layer according to the embodiment of the present invention is typically disposed on the visual recognition side of an image display device, and the protective layer is disposed on the visual recognition side 12. Therefore, the protective layer 12 may be subjected to surface treatments such as Hard Coat (HC) treatment, antireflection treatment, anti-blocking treatment, antiglare treatment, and the like, as necessary. Further, the protective layer 12 may be subjected to a treatment (typically, a (elliptical) polarization function and an ultra-high retardation) as needed to improve the visibility when the protective layer is visually recognized through polarized sunglasses. By performing such a process, even when the display screen is visually recognized through a polarized lens such as polarized sunglasses, excellent visual recognition can be achieved. Therefore, the polarizing plate with the retardation layer is also suitable for use in an image display device that can be used outdoors.

The thickness of the protective layer is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and still more preferably 10 μm to 60 μm. When the surface treatment is performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

The second protective layer is preferably optically isotropic in 1 embodiment. In the present specification, "optically isotropic" means that the in-plane retardation Re (550) is 0nm to 10nm, and the retardation Rth (550) in the thickness direction is-10 nm to +10nm.

D. First phase difference layer

D-1 characteristics of the first phase-difference layer

The in-plane retardation Re (550) of the first retardation layer 21 is as described above 100nm to 200nm, preferably 110nm to 180nm, more preferably 120nm to 160nm, still more preferably 130nm to 150nm. That is, the first retardation layer can function as a so-called λ/4 plate.

The first retardation layer preferably satisfies the relationship of Re (450) < Re (550) and also satisfies the relationship of Re (550) < Re (650) as described above. That is, the first phase difference layer shows a wavelength dependence of anomalous dispersion in which the phase difference value becomes large according to the wavelength of the measurement light. Re (450)/Re (550) of the first retardation layer exceeds 0.5 and is less than 1.0, for example, preferably 0.7 to 0.95, more preferably 0.75 to 0.92, and still more preferably 0.8 to 0.9.Re (650)/Re (550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

The first retardation layer has an in-plane retardation as described above, and thus has a relationship of nx > ny. The first retardation layer exhibits any appropriate refractive index characteristic as long as it has a relationship of nx > ny. The refractive index characteristics of the first retardation layer typically show a relationship of nx > ny.gtoreq.nz. Here, "ny=nz" includes not only the case where ny is identical to nz but also the case where ny is substantially identical. Therefore, ny < nz may be present within a range that does not impair the effects of the present invention. The Nz coefficient of the first retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and still more preferably 0.9 to 1.2. By satisfying such a relationship, when the polarizing plate with a retardation layer is used in an image display device, a very excellent reflection hue can be achieved.

The thickness of the first retardation layer may be set so as to function most appropriately as a λ/4 plate. In other words, the thickness may be set in such a manner that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 15 μm to 70 μm, more preferably 20 μm to 60 μm, and most preferably 20 μm to 50 μm.

The shrinkage of the first retardation layer in the slow axis direction when heated at 80 to 125 ℃ for 180 minutes is, for example, 4% or less, preferably 3.5% or less, and more preferably 3% or less. The lower limit of the shrinkage ratio may be, for example, 0.5%, as the shrinkage ratio is smaller and more preferable. When the shrinkage ratio of the first retardation layer is in such a range, cracking in a severe high-temperature and high-humidity environment can be more favorably suppressed.

The elongation at break of the stretched film constituting the first retardation layer is preferably 200% or more, more preferably 210% or more, still more preferably 220% or more, particularly preferably 245% or more. The upper limit of the elongation at break may be 500%, for example. When the elongation at break of the stretched film constituting the first retardation layer is in such a range, cracking in a severe high-temperature and high-humidity environment can be more favorably suppressed by the synergistic effect with the effect of the above-described shrinkage. In the present specification, "elongation at break" means an elongation at break of a film in fixed unidirectional stretching at a predetermined stretching temperature (for example, tg-2 ℃).

The absolute value of the photoelastic coefficient of the first phase difference layer is preferably 20×10 ^-12 (m ² N) or less, more preferably 1.0X10 ^-12 (m ² /N)～15×10 ^-12 (m ² N), further preferably 2.0X10 ^-12 (m ² /N)～12×10 ^-12 (m ² /N). When the absolute value of the photoelastic coefficient is in such a range, display unevenness can be suppressed when the polarizing plate with the retardation layer is applied to an image display device.

D-2 constituent Material of the first phase-difference layer

The first retardation layer typically contains a resin containing at least 1 bonding group selected from the group consisting of carbonate bonds and ester bonds. In other words, the first retardation layer contains a polycarbonate-based resin, a polyester-based resin, or a polyester-carbonate-based resin (hereinafter, these may be collectively referred to simply as a polycarbonate-based resin).

The polycarbonate resin in 1 embodiment comprises: structural units derived from fluorene-based dihydroxy compounds; structural units derived from isosorbide-based dihydroxy compounds; and a structural unit derived from at least 1 dihydroxy compound selected from the group consisting of alicyclic diol, alicyclic dimethanol, diethylene glycol, triethylene glycol or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin comprises: structural units derived from fluorene-based dihydroxy compounds; structural units derived from isosorbide-based dihydroxy compounds; and a structural unit derived from alicyclic dimethanol and/or a structural unit derived from diethylene glycol, triethylene glycol or polyethylene glycol, further preferably comprising: structural units derived from fluorene-based dihydroxy compounds; structural units derived from isosorbide-based dihydroxy compounds; and structural units derived from diethylene glycol, triethylene glycol or polyethylene glycol. The polycarbonate resin may contain a structural unit derived from another dihydroxy compound, if necessary. Details of the polycarbonate-based resin which can be suitably used in the present invention are described in, for example, japanese patent application laid-open No. 2014-10291, japanese patent application laid-open No. 2014-26262, japanese patent application laid-open No. 2015-212816, japanese patent application laid-open No. 2015-212817, and Japanese patent application laid-open No. 2015-212818, which are incorporated herein by reference.

The polycarbonate resin contains at least 1 structural unit selected from the group consisting of the structural unit represented by the above general formula (I) and/or the structural unit represented by the above general formula (II) in 1 embodiment. These structural units are 2-valent structural units derived from an oligofluorene, and are sometimes referred to as oligofluorene structural units hereinafter. Such a polycarbonate resin has positive refractive index anisotropy.

The first retardation layer may further contain an acrylic resin in embodiment 1. The content of the acrylic resin is typically 0.5 to 1.5 mass%. In the present specification, the percentage or part of the "mass" unit is the same as the percentage or part of the "weight" unit.

The first retardation layer may further contain an antioxidant in embodiment 1. As the antioxidant, any suitable compound may be used. Specific examples thereof include pentaerythritol-tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ]: trade name "Irganox1010" (manufactured by BASF corporation), 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene: trade name "Irganox1330" (manufactured by BASF corporation), tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate: trade name "Irganox3114" (manufactured by BASF corporation), stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate: trade name "Irganox1076" (manufactured by BASF corporation), 2' -thiodiethyl bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ]: trade name "Irganox1035" (manufactured by BASF corporation), N' -hexamethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propanamide ]: trade name "Irganox1098" (manufactured by BASF corporation), bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid ] [ ethylenebis (oxyethylene) ] ester: trade names "Irganox245" (manufactured by BASF corporation), 1, 6-hexanediol bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] trade names "Irganox259" (manufactured by BASF corporation), 4- [ [4, 6-bis (octylthio) -1,3, 5-triazin-2-yl ] amino ] -2, 6-di-tert-butylphenol: trade name "Irganox565" (manufactured by BASF corporation), 2' -methylenebis [6- (2H-benzotriazol-2-yl) -4- (1, 3-tetramethylbutyl) phenol: trade name "ADK STAB LA-31" (manufactured by ADEKA Co., ltd.) and the like. The content of the antioxidant is typically 1.5 to 3.5 mass%.

D-2-1 polycarbonate resin

< Oligofluorene structural unit >

The oligofluorene structural unit is represented by the above general formula (I) or (II). In the general formulae (I) and (II), R ¹ ～R ³ Each independently is a direct bond, substituted or unsubstituted alkylene group of 1 to 4 carbon atoms, R ⁴ ～R ⁹ Each independently is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a halogen atom, a nitro group, or a cyano group. Wherein the method comprises the steps of，R ⁴ ～R ⁹ Optionally identical or different from each other, R ⁴ ～R ⁹ Optionally bonded to each other to form a ring.

The content of the oligofluorene structural unit in the polycarbonate resin is preferably 1 to 40% by mass, more preferably 10 to 35% by mass, still more preferably 15 to 30% by mass, and particularly preferably 18 to 25% by mass, based on the entire resin. If the content of the oligofluorene structural unit is too large, there is a concern that problems such as an excessively large photoelastic coefficient, insufficient reliability, insufficient phase difference manifestation, and the like occur. Further, since the proportion of the oligofluorene structural unit in the resin is high, the molecular design may be narrowed, and the improvement may be difficult when the modification of the resin is required. On the other hand, if the desired anomalous dispersion wavelength dependence is obtained even with a very small amount of the oligofluorene structural unit, in this case, the optical characteristics change sensitively with a slight fluctuation in the content of the oligofluorene structural unit, and thus it is sometimes difficult to manufacture such that each characteristic falls within a certain range.

Details of the oligofluorene structural unit are described in, for example, WO 2015/159928. This publication is incorporated by reference into this specification.

< other structural Unit >

The polycarbonate resin may typically contain other structural units in addition to the oligofluorene structural unit. In 1 embodiment, the other structural units may preferably be derived from a dihydroxy compound or a diester compound. In order to exhibit the target anomalous dispersion wavelength properties, it is necessary to incorporate a structural unit having positive intrinsic birefringence together with an oligofluorene structural unit having negative intrinsic birefringence into the polymer structure, and therefore a dihydroxy compound or a diester compound as a raw material of the structural unit having positive birefringence is further preferable as another monomer for copolymerization.

Examples of the comonomer include a compound into which a structural unit containing an aromatic ring is introduced and a compound having an aliphatic structure in which a structural unit containing an aromatic ring is not introduced.

Specific examples of the above-mentioned compounds having an aliphatic structure are given below. Dihydroxy compounds of linear aliphatic hydrocarbons such as ethylene glycol, 1, 3-propanediol, 1, 2-propanediol, 1, 4-butanediol, 1, 3-butanediol, 1, 2-butanediol, 1, 5-heptanediol, 1, 6-hexanediol, 1, 9-nonanediol, 1, 10-decanediol, and 1, 12-dodecanediol; dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol; a secondary alcohol or tertiary alcohol dihydroxy compound which is an alicyclic hydrocarbon, such as 1, 2-cyclohexanediol, 1, 4-cyclohexanediol, 1, 3-adamantanediol, hydrogenated bisphenol a, and 2, 4-tetramethyl-1, 3-cyclobutanediol; dihydroxyl compounds as primary alcohols of alicyclic hydrocarbons, exemplified by dihydroxyl compounds derived from terpene compounds such as 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2, 6-decahydronaphthalene dimethanol, 1, 5-decahydronaphthalene dimethanol, 2, 3-norbornane dimethanol, 2, 5-norbornane dimethanol, 1, 3-adamantane dimethanol, and limonene; alkylene oxide glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and polypropylene glycol; dihydroxy compounds having a cyclic ether structure such as isosorbide; dihydroxy compounds having a cyclic acetal structure such as spiroglycol and dioxane glycol; alicyclic dicarboxylic acids such as 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid and 1, 4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like.

Specific examples of the compound capable of introducing a structural unit containing an aromatic ring are as follows. 2, 2-bis (4-hydroxyphenyl) propane, 2-bis (3-methyl-4-hydroxyphenyl) propane, 2-bis (4-hydroxy-3, 5-dimethylphenyl) propane, 2-bis (4-hydroxy-3, 5-diethylphenyl) propane 2, 2-bis (4-hydroxy- (3-phenyl) propane, 2-bis (4-hydroxy- (3, 5-diphenyl) phenyl) propane, 2-bis (4-hydroxy-3, 5-dibromophenyl) propane, bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane 2, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) pentane, 1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 1-bis (4-hydroxyphenyl) -2-ethylhexane, 1-bis (4-hydroxyphenyl) decane, bis (4-hydroxy-3-nitrophenyl) methane, 3-bis (4-hydroxyphenyl) pentane, 1, 3-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, aromatic bisphenol compounds such as 1, 3-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, 2-bis (4-hydroxyphenyl) hexafluoropropane, 1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4 '-dihydroxydiphenyl sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxy-3-methylphenyl) sulfide, bis (4-hydroxyphenyl) disulfide, 4' -dihydroxydiphenyl ether, 4 '-dihydroxy-3, 3' -dichlorodiphenyl ether; dihydroxy compounds having an ether group bonded to an aromatic group, such as 2, 2-bis (4- (2-hydroxyethoxy) phenyl) propane, 2-bis (4- (2-hydroxypropoxy) phenyl) propane, 1, 3-bis (2-hydroxyethoxy) benzene, 4' -bis (2-hydroxyethoxy) biphenyl, and bis (4- (2-hydroxyethoxy) phenyl) sulfone; aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4' -diphenyldicarboxylic acid, 4' -diphenylether dicarboxylic acid, 4' -benzophenone dicarboxylic acid, 4' -diphenoxyethane dicarboxylic acid, 4' -diphenylsulfone dicarboxylic acid, and 2, 6-naphthalene dicarboxylic acid.

The aliphatic dicarboxylic acid and the aromatic dicarboxylic acid components mentioned above may be used as the dicarboxylic acid itself as the raw material of the polyester carbonate, but according to the production method, dicarboxylic acid esters such as methyl ester and phenyl ester, and dicarboxylic acid derivatives such as dicarboxylic acid halides may be used as the raw material.

As the comonomer, conventionally known dihydroxy compounds having a fluorene ring such as 9, 9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9-bis (4-hydroxyphenyl) fluorene and 9, 9-bis (4-hydroxy-3-methylphenyl) fluorene, and dicarboxylic acid compounds having a fluorene ring may be used in combination with the oligofluorene compound.

The resin used in the embodiment of the present invention preferably contains a structural unit represented by the following formula (III) as a copolymerizable component in the structural unit that can be introduced by the compound having an alicyclic structure.

As the dihydroxy compound into which the structural unit of the above formula (III) can be introduced, spiroglycol can be used.

The resin used in the embodiment of the present invention preferably contains 5 to 90 mass% of the structural unit represented by the formula (III). The upper limit is more preferably 70 mass% or less, particularly preferably 50 mass% or less. The lower limit is more preferably 10 mass% or more, still more preferably 20 mass% or more, particularly preferably 25 mass% or more. When the content of the structural unit represented by the formula (III) is not less than the lower limit, sufficient mechanical properties, heat resistance and low photoelastic coefficient are obtained. Further, the compatibility with the acrylic resin is improved, and the transparency of the obtained resin composition can be further improved. Further, since the rate of polymerization reaction is relatively low, the content of spiro diol is suppressed to the above upper limit or less, whereby the polymerization reaction can be easily controlled.

The resin used in the embodiment of the present invention may further have a structural unit represented by the following formula (IV) as a copolymerization component.

Examples of the dihydroxy compound into which the structural unit represented by the formula (IV) can be introduced include Isosorbide (ISB), isomannide, isoidide (isoidide) in a stereoisomeric relationship. These may be used alone or in combination of 1 or more than 2.

The resin used in the embodiment of the present invention preferably contains 5 to 90 mass% of the structural unit represented by the formula (IV). The upper limit is more preferably 70 mass% or less, particularly preferably 50 mass% or less. The lower limit is more preferably 10 mass% or more, particularly preferably 15 mass% or more. When the content of the structural unit represented by the formula (IV) is not less than the lower limit, sufficient mechanical properties, heat resistance and low photoelastic coefficient can be obtained. Further, since the structural unit represented by the formula (IV) has a characteristic of high water absorption, when the content of the structural unit represented by the formula (IV) is equal to or less than the upper limit, the dimensional change of the molded article due to water absorption can be suppressed to an allowable range.

The resins used in embodiments of the present invention may also contain additional structural units. The structural unit may be referred to as "other structural unit". As the monomer having other structural units, 1, 4-cyclohexanedimethanol, tricyclodecanedimethanol, 1, 4-cyclohexanedicarboxylic acid (and derivatives thereof) are more preferably used, and 1, 4-cyclohexanedimethanol and tricyclodecanedimethanol are particularly preferred. Resins comprising structural units derived from these monomers are excellent in balance of optical properties, heat resistance, mechanical properties, and the like. Further, since the polymerization reactivity of the diester compound is relatively low, it is preferable not to use a diester compound other than the diester compound containing an oligofluorene structural unit from the viewpoint of improving the reaction efficiency.

The glass transition temperature (Tg) of the resin used in the embodiment of the present invention is preferably 110 ℃ or more and 160 ℃ or less. The upper limit is more preferably 155℃or lower, still more preferably 150℃or lower, particularly preferably 145℃or lower. The lower limit is more preferably 120℃or higher, particularly preferably 130℃or higher. When the glass transition temperature is outside the above range, there is a possibility that the heat resistance is deteriorated, and dimensional change after film formation is caused, and the reliability of the quality under the use condition of the first retardation layer is deteriorated. On the other hand, if the glass transition temperature is too high, there are cases where film thickness unevenness occurs during film formation, or the film becomes brittle and the stretchability deteriorates, and the transparency of the film is impaired.

D-2-2 acrylic resin

As the acrylic resin, an acrylic resin as a thermoplastic resin can be used. Examples of the monomer as a structural unit of the acrylic resin include the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, glycidyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, glycidyl (meth) acrylate, and mixtures thereof dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acryloyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxyethyl maleate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, pentamethylpiperidine (meth) acrylate, tetramethylpiperidine (meth) acrylate, dimethylaminoethyl (meth) acrylate, and, diethylaminoethyl (meth) acrylate, cyclopentyl methacrylate, cyclopentyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, cycloheptyl methacrylate, cycloheptyl acrylate, cyclooctyl methacrylate, cyclooctyl acrylate, cyclododecyl methacrylate, cyclododecyl acrylate. These may be used alone or in combination of 2 or more. The mode of using 2 or more monomers in combination includes: copolymerization of 2 or more monomers, a mixture of 2 or more homopolymers of 1 monomer, and combinations thereof. Further, other monomers copolymerizable with these acrylic monomers (for example, olefin monomers and vinyl monomers) may be used in combination.

The acrylic resin contains structural units derived from methyl methacrylate. The content of the structural unit derived from methyl methacrylate in the acrylic resin is preferably 70% by mass or more and 100% by mass or less. The lower limit is more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more. When the amount is within this range, excellent compatibility with the polycarbonate resin of the present invention is obtained. As the structural unit other than methyl methacrylate, methyl acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, and styrene are preferably used. By copolymerizing methyl acrylate, thermal stability can be improved. Since the refractive index of the acrylic resin can be adjusted by using phenyl (meth) acrylate, benzyl (meth) acrylate, and styrene, the transparency of the resulting resin composition can be improved by adapting the refractive index of the resin to be combined. By using such an acrylic resin, an anomalous dispersion retardation film having excellent stretchability and retardation performance and having a small haze can be obtained.

The weight average molecular weight Mw of the acrylic resin is 10,000 to 200,000. The lower limit is preferably 30,000 or more, particularly preferably 50,000 or more. The upper limit is preferably 180,000 or less, particularly preferably 150,000 or less. When the molecular weight is in such a range, compatibility with the polycarbonate resin is obtained, and therefore, the transparency of the final retardation film (retardation layer) can be improved, and the effect of sufficiently improving the stretchability at the time of stretching can be obtained. The weight average molecular weight mentioned above is a molecular weight in terms of polystyrene measured by GPC. In addition, from the viewpoint of compatibility, it is preferable that the acrylic resin contains substantially no branched structure. The absence of the branched structure can be confirmed by unimodal GPC curve of the acrylic resin.

D-2-3. Mixing of polycarbonate resin and acrylic resin

When a polycarbonate resin and an acrylic resin are used in combination, the polycarbonate resin and the acrylic resin are mixed and are used as a resin composition for a method for producing a retardation film (first retardation layer) (the production method is described in the following item D-3). The polycarbonate resin and the acrylic resin may be preferably mixed in a molten state. As a method of mixing in a molten state, melt kneading using an extruder is typically exemplified. The kneading temperature (melting resin temperature) is preferably 200℃to 280℃and more preferably 220℃to 270℃and even more preferably 230℃to 260 ℃. When the kneading temperature is in such a range, thermal decomposition can be suppressed, and pellets of a resin composition in which both resins are uniformly mixed can be obtained. If the temperature of the molten resin in the extruder exceeds 280 ℃, coloration and/or thermal decomposition of the resin sometimes occur. On the other hand, if the temperature of the molten resin in the extruder is lower than 200 ℃, the viscosity of the resin may be too high, which may cause an excessive load to be applied to the extruder or insufficient melting of the resin. Any suitable configuration may be used as the configuration of the extruder, the screw, and the like. In order to obtain transparency of a resin which can withstand the use of an optical film, a twin screw extruder is preferably used. Further, since there is a concern that the cooling roll and the conveying roll may be contaminated in the film-forming step and the stretching step by the remaining low molecular components in the resin and the low molecular weight thermally decomposed components in the extrusion kneading, an extruder having a vacuum vent is preferably used for removing the components.

The content of the acrylic resin in the resin composition (as a result of the first retardation layer) is 0.5 mass% or more and 2.0 mass% or less as described above. The lower limit is more preferably 0.6 mass% or more. The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.9% by mass or less, particularly preferably 0.8% by mass or less. By blending the acrylic resin into the polycarbonate resin at a very limited ratio in this way, the stretchability and the retardation manifestation can be significantly increased. Further, haze can be suppressed. Such effects are not theoretically clear, and are unexpected excellent effects obtained by trial and error. If the content of the acrylic resin is too small, the above-mentioned effect may not be obtained. On the other hand, if the content of the acrylic resin is too large, haze may be high. In addition, the stretchability and the retardation performance are also insufficient and often lower than those in the above range.

For the purpose of modifying the mechanical properties and/or solvent resistance, the resin composition may be blended with a synthetic resin such AS an aromatic polycarbonate, an aliphatic polycarbonate, an aromatic polyester, an aliphatic polyester, a polyamide, a polystyrene, a polyolefin, an acrylic, an amorphous polyolefin, ABS, AS, polylactic acid, polybutylene succinate, a rubber, or a combination of these.

The resin composition may further comprise additives. Specific examples of the additives include heat stabilizers, antioxidants, catalyst deactivators, ultraviolet absorbers, light stabilizers, mold release agents, coloring pigments, impact modifiers, antistatic agents, slip agents, lubricants, plasticizers, solubilizing agents, nucleating agents, flame retardants, inorganic fillers, and foaming agents. The kind, amount, combination, content, and the like of the additives contained in the resin composition may be appropriately set according to the purpose.

D-3 method for forming first phase difference layer

The first retardation layer is obtained by forming a film from the polycarbonate resin (resin composition when an acrylic resin is used in combination) described in the above item D-2, and stretching the film. As a method for forming the thin film, any suitable forming method can be used. Specific examples thereof include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, casting (e.g., casting), calendaring, and hot pressing. Among them, an extrusion molding method or a casting coating method capable of improving the smoothness of the obtained film, and obtaining good optical uniformity is preferable. In the casting method, there is a concern that problems may occur due to residual solvents, and therefore, extrusion molding is particularly preferred, and among them, the melt extrusion molding method using a T die is preferred from the viewpoints of productivity of the film and easiness of the subsequent stretching treatment. The molding conditions can be appropriately set according to the composition and type of the resin to be used, the desired properties of the first retardation layer, and the like. Thus, a resin film containing a polycarbonate resin and, if necessary, an acrylic resin can be obtained.

The thickness of the resin film (unstretched film) may be set to any appropriate value depending on the desired thickness of the obtained first retardation layer, desired optical characteristics, stretching conditions described later, and the like. Preferably 50 μm to 300. Mu.m.

The stretching may be performed by any suitable stretching method or stretching conditions (for example, stretching temperature, stretching ratio, stretching direction). Specifically, various stretching methods such as free end stretching, fixed end stretching, free end shrinkage, and fixed end shrinkage may be used alone or simultaneously or sequentially. The stretching direction may be performed in various directions and dimensions such as a longitudinal direction, a width direction, a thickness direction, and an oblique direction.

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

The stretching temperature of the film is preferably in the range of glass transition temperature (Tg) to tg+30 ℃, more preferably in the range of Tg to tg+15 ℃, and most preferably in the range of Tg to tg+10 ℃ in 1 embodiment. When the acrylic resin is used in combination, the stretching temperature is a temperature of Tg or less. In general, when a film of a polycarbonate resin is stretched, the film is in a glass state at a temperature of Tg or less, and thus stretching is not substantially achieved. On the other hand, by blending a small amount of an acrylic resin (typically polymethyl methacrylate), the Tg of the polycarbonate resin is not substantially changed, and stretching below Tg can be achieved. Further, it is not theoretically clear that by stretching at Tg or lower, an anomalous dispersion retardation film (first retardation layer) excellent in stretchability and retardation expression and having a small haze can be obtained. Specifically, the stretching temperature is preferably from Tg to Tg-10deg.C, more preferably from Tg to Tg-8deg.C, and even more preferably from Tg to Tg-5deg.C. The film may be stretched appropriately even at a temperature higher than Tg, for example, at about tg+5℃, or at about tg+2℃.

The stretched film obtained as described above is subjected to a heating treatment of heating at 105 ℃ or higher for 2 minutes or longer, as required. By performing the heat treatment, the first retardation layer having the above-described desired shrinkage ratio can be formed. The heating temperature is preferably 105℃to 140℃and more preferably 110℃to 130℃and still more preferably 115℃to 125 ℃. The heating time is preferably 2 minutes to 150 minutes, more preferably 3 minutes to 120 minutes, and still more preferably 5 minutes to 60 minutes.

The stretched film may be subjected to a relaxation treatment as needed. This can alleviate the stress generated by stretching, and can form the retardation layer having the desired shrinkage ratio. As the mild processing conditions, any suitable conditions may be employed. For example, the stretched film is contracted at a predetermined relaxation temperature and a predetermined relaxation rate (shrinkage rate) along the stretching direction. The temperature for moderation is preferably 60℃to 150 ℃. The relaxation rate is preferably 3% to 6%. In the case of performing the relaxing process, the relaxing process may be typically performed before the heating process.

Thus, a retardation film constituting the first retardation layer can be obtained.

E. Second phase difference layer

The second phase difference layer may be a so-called positive C plate whose refractive index characteristics show a relationship of nz > nx=ny as described above. By using the positive C plate as the second phase difference layer, reflection in the oblique direction can be prevented well, and a wide viewing angle of the antireflection function can be achieved. In this case, the retardation Rth (550) in the thickness direction of the second phase difference layer is preferably-50 nm to-300 nm, more preferably-70 nm to-250 nm, still more preferably-90 nm to-200 nm, particularly preferably-100 nm to-180 nm. Here, "nx=ny" includes not only the case where nx and ny are exactly equal but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re (550) of the second phase difference layer may be less than 10nm.

The second phase difference layer having refractive index characteristics of nz > nx=ny may be formed of any suitable material. The second phase difference layer is preferably formed of a thin film containing a liquid crystal material fixed in a homeotropic (homeotropic) 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 method for forming the liquid crystal compound and the retardation layer include those described in [0020] to [0028] of JP-A-2002-333642 and a method for forming the retardation layer. In this case, the thickness of the second phase difference layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and still more preferably 0.5 μm to 5 μm.

F. A first resin layer

The first resin layer may have any suitable structure that satisfies the storage modulus. The first resin layer may function as a heat and moisture resistant layer, for example. Specifically, by providing the first resin layer, a polarizing plate with a retardation layer having excellent durability even in a severe high-temperature and high-humidity environment can be realized.

The first resin layer preferably has substantially optical isotropy. The in-plane retardation Re (550) of the first resin layer is preferably 0nm to 10nm, more preferably 0nm to 5nm, still more preferably 0nm to 3nm, particularly preferably 0nm to 2nm. The retardation Rth (550) in the thickness direction of the first resin layer is preferably-10 nm to +10nm, more preferably-5 nm to +5nm, still more preferably-3 nm to +3nm, particularly preferably-2 nm to +2nm. When Re (550) and Rth (550) of the first resin layer are in such a range, adverse effects on display characteristics can be prevented when applied to an image display device.

The higher the light transmittance at 380nm at a thickness of 3 μm of the first resin layer, the more preferable. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more. When the light transmittance is in such a range, desired transparency can be ensured. The light transmittance can be measured by, for example, a method according to ASTM-D-1003.

The lower the haze of the first resin layer is, the more preferable. Specifically, the haze is preferably 5% or less, more preferably 3% or less, further preferably 1.5% or less, and particularly preferably 1% or less. When the haze is 5% or less, a good transparent feeling can be imparted to the polarizing plate with the retardation layer. As a result, the display content of the image display device can be visually recognized well.

In embodiment 1, the higher the adhesion between the first resin layer and the first retardation layer, the more preferable. Specifically, the adhesion is preferably at most 2 minutes, more preferably at most 1 minute, and particularly preferably at most 0 minute in the checkerboard peel test described in JIS K5600-5-6. When the adhesion is 2 minutes or less by the checkered peeling test, peeling of the polarizing plate with the retardation layer in a severe high-temperature and high-humidity environment can be favorably suppressed, and problems relating to appearance such as peeling at the time of reworking can be suppressed.

As described above, the first resin layer is typically a cured layer or a solidified layer of resin. The cured layer may be, for example, a cured layer of a thermosetting resin, an active energy ray curable resin, or an active energy ray curable resin. Specific examples of the cured layer include a hard coat layer, an adhesive layer composed of an active energy ray-curable adhesive, and a crosslinked layer based on a crosslinking agent, in addition to a mere cured layer. The solidifying layer may be, for example, a solidifying layer of a coating film of an organic solvent solution of a thermoplastic resin. These may be used alone or in combination of two or more.

(hard coat)

The hard coat layer (essentially, the composition forming the hard coat layer) contains a curing component and a representative photopolymerization initiator. Typical examples of the curing component include active energy ray-curable (meth) acrylates. Examples of the active energy ray-curable (meth) acrylate include ultraviolet-curable (meth) acrylate and electron beam-curable (meth) acrylate. Preferably ultraviolet curable (meth) acrylate. This is because the hard coat layer can be efficiently formed by a simple processing operation. The ultraviolet curable (meth) acrylate includes ultraviolet curable monomers, oligomers, polymers, and the like. The ultraviolet curable (meth) acrylate contains a monomer component and an oligomer component having an ultraviolet polymerizable functional group, preferably 2 or more, more preferably 3 to 6. Specific examples of the ultraviolet-curable (meth) acrylate include urethane acrylate, pentaerythritol triacrylate, ethoxylated glycerol triacrylate, and polyether urethane diacrylate. In addition to these, a curing component of an active energy ray-curable adhesive to be described later may be used. The curing components may be used alone or in combination of 2 or more. The curing method may be a radical polymerization method or a cationic polymerization method. In the 1 embodiment, an organic-inorganic hybrid material in which silica particles, polysilsesquioxane compounds, and the like are blended with (meth) acrylic acid esters can be used. The constituent materials and the forming method of the hard coat layer are described in, for example, japanese patent application laid-open publication No. 2011-237789, japanese patent application laid-open publication No. 2020-064236, and Japanese patent application laid-open publication No. 2010-152331. The disclosures of these publications are incorporated by reference into this specification. In the present specification, "meth) acrylic acid" means acrylic acid and/or methacrylic acid. In addition, (meth) acrylic acid is sometimes simply referred to as acrylic acid.

(active energy ray-curable adhesive)

Examples of the active energy ray-curable adhesive include ultraviolet ray-curable adhesives and electron beam-curable adhesives. From the viewpoint of the curing mechanism, examples of the active energy ray-curable adhesive include a radical-curable adhesive, a cationic-curable adhesive, an anionic-curable adhesive, a radical-curable adhesive, and a cationic-curable adhesive.

The adhesive contains a curing component and a typical photopolymerization initiator, as in the case of the composition for forming the hard coat layer. As the curing component, monomers and/or oligomers having a functional group such as a (meth) acrylate group or a (meth) acrylamide group are typically exemplified. Specific examples of the curing component include tripropylene glycol diacrylate, 1, 6-hexanediol diacrylate, 1, 9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trimethylolpropane methylacrylate, dioxane glycol diacrylate, trimethylolpropane triacrylate, glycerol triacrylate, EO-modified diglycerol tetraacrylate, gamma-butyrolactone acrylate, polyethylene glycol diacrylate, hydroxypivalate neopentyl glycol acrylate adduct, acryloylmorpholine, unsaturated fatty acid hydroxyalkyl ester modified epsilon-caprolactone, N-methylpyrrolidone, diethylacrylamide, hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethacrylamide, N-ethoxymethacrylamide, 3, 4-epoxycyclohexenylmethyl-3 ',4' -epoxycyclohexene carboxylate, neopentyl glycol glycidyl ether, dicyclopentadiene type epoxy resin. As the curing component, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 4-hydroxybutyl acrylate, neopentyl glycol diacrylate, isocyanuric acid EO-modified triacrylate, and the like can be used. In addition to these, the curing component of the hard coat layer described above may be used. The curing components may be used alone or in combination of 2 or more. The adhesive may contain an oligomer component in addition to the above-mentioned curing component. By using the oligomer component, the viscosity of the adhesive before curing can be reduced, and the workability can be improved. Typical examples of the oligomer component include (meth) acrylic oligomers and urethane (meth) acrylic oligomers.

(crosslinking agent-based crosslinking layer)

The crosslinked layer (essentially the composition forming the crosslinked layer) contains a curing component and a crosslinking agent. Examples of the curing component include the hard coat layer and the active energy ray-curable adhesive described above. The crosslinking agent may be a thermal crosslinking agent or a photocrosslinking agent. That is, the crosslinked layer may be a thermally crosslinked layer or a photocrosslinked layer. Examples of the thermal crosslinking agent include an organic crosslinking agent and a polyfunctional metal chelate. Examples of the organic crosslinking agent include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. In the polyfunctional metal chelate, the polyvalent metal is covalently bonded or coordinately bonded to the organic compound. Examples of the photocrosslinking agent include photoacid generators. Examples of the photoacid generator include organic peroxides. The thermal crosslinking agent or the photocrosslinking agent may each be used alone or in combination of 2 or more.

(cured layer of thermosetting resin)

As the thermosetting resin, any suitable thermosetting resin may be used as long as the cured layer has the above-described desired storage modulus. Typical examples of the thermosetting resin include epoxy resins, (meth) acrylic resins, unsaturated polyester resins, polyurethane resins, alkyd resins, melamine resins, urea resins, and phenolic resins. The thermosetting resin may be blended with an oxetane compound (monomer, oligomer, polymer), for example.

(solidifying layer)

The solidified layer may be a solidified layer of a coating film of an organic solvent solution of, for example, a thermoplastic resin, as described above. As the thermoplastic resin, any suitable thermoplastic resin may be used as long as the solidified layer has the above-described desired storage modulus. Typical examples of the thermoplastic resin include (meth) acrylic resins and epoxy resins.

The glass transition temperature (Tg) of the (meth) acrylic resin is preferably 100℃to 220℃and more preferably 110℃to 200℃and still more preferably 120℃to 160 ℃. The (meth) acrylic resin may have a repeating unit including a ring structure. Examples of the repeating unit having a ring structure include a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. The repeating unit including the ring structure may include only 1 kind or 2 or more kinds of repeating units of the (meth) acrylic resin. The (meth) acrylic resin may be a copolymer of a (meth) acrylic monomer and a boron-containing monomer (boron-containing (meth) acrylic resin). The boron-containing (meth) acrylic resin may have such a repeating unit containing a ring structure as described above.

As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring, the adhesion between the solidified layer and the first retardation layer is improved. Examples of the epoxy resin having an aromatic ring include bisphenol type epoxy resins such as bisphenol a type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde phenol novolac epoxy resin and the like; glycidyl ethers of tetrahydroxyphenyl methane, glycidyl ethers of tetrahydroxybenzophenone, epoxy resins of epoxy type such as epoxidized polyvinyl phenol, naphthol type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, and the like. Bisphenol A type epoxy resin, biphenyl type epoxy resin, bisphenol F type epoxy resin are preferably used. The epoxy resin may be used in an amount of 1 or 2 or more.

As the organic solvent, any suitable organic solvent that can dissolve or uniformly disperse the thermoplastic resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.

The resin concentration of the organic solvent solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. In such a resin concentration, a uniform coating film can be formed to adhere to the first retardation layer.

The thickness of the first resin layer is preferably 500nm to 5. Mu.m, more preferably 800nm to 4. Mu.m, still more preferably 1 μm to 3. Mu.m. Even if the first resin layer has such a very small thickness, a polarizing plate with a retardation layer having excellent durability even in a severe high-temperature and high-humidity environment can be realized. If the thickness of the first resin layer is too small, the formation of the first resin layer itself may become difficult, and even if the formation is performed, the effect may be insufficient, and if the thickness of the first resin layer is too large, the following problems may occur: the first resin layer itself becomes difficult to form due to curling caused by curing shrinkage, or is insufficiently cured, and the first resin layer functions as a fragile layer instead.

The first resin layer is typically formed by applying a composition for forming the first resin layer to the first retardation layer, and curing or solidifying the applied film. Specifically, the first resin layer is formed by applying a composition forming a layer to the second main surface of the first retardation layer, and curing or solidifying the applied film. In the case where the first resin layer is an active energy ray-curable layer, the coating film can be cured by irradiation of active energy rays (for example, visible rays, ultraviolet rays, electron beams) to the coating film. In the case where the first resin layer is a thermosetting layer, the coating film can be cured by heating the coating film. When the first resin layer is a solidified layer, the coated film can be solidified by heating the coated film.

The formation surface (for example, the surface of the first retardation layer) on which the first resin layer is formed may be subjected to surface modification in advance. Specifically, the surface energy of the formed surface can be increased by surface modification. The shear fracture strength of the resulting first resin layer can be adjusted by surface modification, for example. In addition, the adhesion between the first resin layer and the first retardation layer can be improved. The surface modification is performed by, for example, corona treatment or plasma treatment. These may be used alone or in combination.

G. Second resin layer

As described above, the second resin layer can reduce the influence (may have a blocking function) that the polarizer may have on other members. For example, the movement of iodine that can be contained in the polarizer can be suppressed, and when the polarizing plate with the retardation layer is mounted on an image display device, corrosion of a metal member of the image display device can be significantly suppressed. The second resin layer is typically a solid or thermally cured product of a coating film of an organic solvent solution of a resin. With such a configuration, the thickness can be made extremely thin (for example, 10 μm or less). The thickness of the second resin layer is preferably 5 μm or less, more preferably 1 μm or less, and still more preferably 0.7 μm or less. On the other hand, the thickness of the second resin layer is preferably 0.05 μm or more, more preferably 0.08 μm or more, still more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. Further, with such a configuration, the second resin layer can be directly formed on the polarizing plate (polarizing material) without the adhesive layer. Such a second resin layer has an advantage of excellent humidification durability because it has less hygroscopicity and moisture permeability than the solid state of an aqueous coating film such as an aqueous solution or an aqueous dispersion. As a result, a polarizing plate with a retardation layer having excellent durability and optical characteristics maintained even in a high-temperature and high-humidity environment can be obtained. In addition, such a second resin layer can suppress adverse effects on the polarizing plate (polarizing material) caused by ultraviolet irradiation, for example, compared with a cured product of an ultraviolet-curable resin. The second resin layer is preferably a solid of a coating film of an organic solvent solution of a resin. The solid material has less shrinkage at the time of film formation and does not contain residual monomers or the like as compared with the cured material, and therefore, deterioration of the film itself can be suppressed, and adverse effects on a polarizing plate (polarizing material) due to residual monomers or the like can be suppressed.

The glass transition temperature (Tg) of the resin constituting the second resin layer is preferably 85 ℃ or higher, and the weight average molecular weight (Mw) is preferably 50000 or higher. When Tg and Mw are in such a range, the synergistic effect of the second resin layer formed by the solid or thermosetting material of the coating film of the organic solvent solution of the resin can significantly suppress the movement of iodine that can be contained in the polarizer, as well as being extremely thin. The Tg of the resin constituting the second resin layer is preferably 90 ℃ or higher, more preferably 100 ℃ or higher, still more preferably 110 ℃ or higher, particularly preferably 120 ℃ or higher. The upper limit of Tg may be, for example, 200 ℃. The Mw of the resin constituting the second resin layer is preferably 60000 or more, more preferably 70000 or more, and still more preferably 80000 or more. On the other hand, the Mw is preferably less than 500000, preferably 400000 or less, and more preferably 300000 or less.

The second resin layer further contains an isocyanate compound in addition to the above resin. As the isocyanate compound, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives (e.g., modifications and adducts) thereof are preferably used. These may be used alone or in combination. By using such an isocyanate compound, excellent adhesion to a polarizing plate (polarizing element) can be achieved. As the isocyanate compound, at least one of hexamethylene diisocyanate or a derivative thereof is preferably used in addition to the above. With such a configuration, the adhesive layer has more excellent adhesion to an adhesive layer described later.

The content of the resin in the second resin layer is, for example, 50% by weight or more, and may be 55% by weight or more, or 60% by weight or more. On the other hand, the content of the resin in the second resin layer is, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less. The content of the isocyanate compound in the second resin layer is, for example, 10% by weight or more, and may be 15% by weight or more, or may be 20% by weight or more. On the other hand, the content of the isocyanate compound in the second resin layer is, for example, 50% by weight or less, 45% by weight or less, or 40% by weight or less. The hexamethylene diisocyanate and its derivatives are preferably used in an amount of 10 to 40 parts by weight relative to 100 parts by weight of the isocyanate compound.

As the resin constituting the second resin layer, any suitable thermoplastic resin or thermosetting resin that can form a solid or thermosetting coating film of an organic solvent solution can be used. Thermoplastic resins are preferred. Examples of the thermoplastic resin include epoxy resins and acrylic resins. An epoxy resin and an acrylic resin may be used in combination. Representative examples of the epoxy resin and the acrylic resin that can be used in the second resin layer are described below.

< epoxy resin >

As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring as the epoxy resin, excellent adhesion to a polarizing plate (polarizing element) can be achieved. Examples of the epoxy resin having an aromatic ring include bisphenol type epoxy resins such as bisphenol a type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde phenol novolac epoxy resin and the like; glycidyl ethers of tetrahydroxyphenyl methane, glycidyl ethers of tetrahydroxybenzophenone, epoxy resins of epoxy type such as epoxidized polyvinyl phenol, naphthol type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, and the like. Bisphenol A type epoxy resin, biphenyl type epoxy resin, bisphenol F type epoxy resin are preferably used. The epoxy resin may be used in an amount of 1 or 2 or more.

< acrylic resin >

The acrylic resin typically contains a repeating unit derived from a (meth) acrylate monomer having a linear or branched structure as a main component. In the present specification, (meth) acrylic acid means acrylic acid and/or methacrylic acid. The acrylic resin may contain repeating units derived from any suitable comonomer that is satisfactory. Examples of the comonomer(s) include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth) acrylates, and heterocyclic ring-containing vinyl monomers. By appropriately setting the kind, number, combination, copolymerization ratio, and the like of the monomer units, an acrylic resin having the above-described predetermined Tg and Mw can be obtained.

< boron-containing acrylic resin >

The acrylic resin includes, in 1 embodiment, a copolymer (hereinafter, sometimes referred to as a boron-containing acrylic resin) obtained by polymerizing a monomer mixture including more than 50 parts by weight of a (meth) acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1) (hereinafter, sometimes referred to as a comonomer):

(wherein X represents a functional group comprising at least 1 reactive group selected from the group consisting of vinyl, (meth) acryl, styryl, (meth) acrylamido, vinyl ether, epoxy, oxetanyl, hydroxyl, amino, aldehyde, and carboxyl, R ¹ R is R ² Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aryl group, or an optionally substituted heterocyclic group, R ¹ R is R ² Optionally linked to each other to form a ring).

The boron-containing acrylic resin typically has a repeating unit represented by the following formula. The boron-containing acrylic resin has a substituent (for example, a repeating unit of k in the following formula) in a side chain by polymerizing a monomer mixture containing a comonomer represented by the formula (1) and a (meth) acrylic monomer. This can realize excellent adhesion to a polarizing plate (polarizing material). The boron-containing substituent may be contained continuously (i.e., in a block form) or randomly in the boron-containing acrylic resin.

(in the formula (I),R ⁶ represents an arbitrary functional group, j and k represent integers of 1 or more).

(meth) acrylic monomer ]

As the (meth) acrylic monomer, any suitable (meth) acrylic monomer may be used. For example, (meth) acrylate monomers having a linear or branched structure, and (meth) acrylate monomers having a cyclic structure are exemplified.

Examples of the (meth) acrylic acid ester monomer having a linear or branched structure include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, methyl 2-ethylhexyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. Methyl (meth) acrylate is preferably used. The (meth) acrylic acid ester monomer may be used in an amount of 1 or 2 or more.

Examples of the (meth) acrylic ester monomer having a cyclic structure include biphenyl-containing monomers such as cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, biphenyl (meth) acrylate, o-biphenyloxyethyl (meth) acrylate, o-biphenyloxyethoxyethyl acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth) acrylate, o-biphenyloxy-2-hydroxypropyl (meth) acrylate, p-biphenyloxy-2-hydroxypropyl (meth) acrylate, m-biphenyloxy-2-hydroxypropyl (meth) acrylate, N- (meth) acryloyloxyethyl-p-biphenylyl=urethane, N- (meth) acryloyloxyethyl-m-biphenyl=urethane, and terphenylphenol glycidyl ether acrylate, and tri-biphenyl (meth) acrylate. Preferably, 1-adamantyl (meth) acrylate and dicyclopentanyl (meth) acrylate are used. By using these monomers, a polymer having a high glass transition temperature is obtained. These monomers may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

In addition, in addition to the (meth) acrylate monomer, a silsesquioxane compound having a (meth) acryloyl group may be used. By using a silsesquioxane compound, an acrylic polymer having a high glass transition temperature is obtained. Silsesquioxane compounds are known to have various framework structures such as a cage structure, a ladder structure, a random structure, and the like. The silsesquioxane compound may have only 1 of these structures, or may have 2 or more structures. The silsesquioxane compound may be used in an amount of 1 or 2 or more.

As the (meth) acryl-containing silsesquioxane compound, for example, MAC grade and AC grade of the SQ series of the eastern asia synthesis corporation may be used. The MAC level is a silsesquioxane compound containing a methacryloyl group, and specifically, examples thereof include MAC-SQ TM-100, MAC-SQ SI-20, and MAC-SQ HDM. The AC grade is an acryl-containing silsesquioxane compound, and examples thereof include AC-SQ TA-100 and AC-SQ SI-20.

More than 50 parts by weight of the (meth) acrylic monomer is used relative to 100 parts by weight of the monomer mixture.

< comonomer >

As the comonomer, a monomer represented by the above formula (1) can be used. By using such a comonomer, a substituent containing boron is introduced into the side chain of the resulting polymer. The comonomer may be used alone or in combination of 1 or more than 2.

The aliphatic hydrocarbon group in the above formula (1) may be a straight-chain or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. Examples of the aryl group include a phenyl group having 6 to 20 carbon atoms optionally having a substituent, a naphthyl group having 10 to 20 carbon atoms optionally having a substituent, and the like. The heterocyclic group may be a 5-membered or 6-membered ring group containing at least 1 heteroatom, optionally having a substituent. Needs to be as followsIllustratively, R is ¹ R is R ² Optionally linked to each other to form a ring. R is R ¹ R is R ² Preferably a hydrogen atom, or a straight or branched alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom.

The reactive group included in the functional group represented by X is at least 1 selected from the group consisting of a vinyl group, a (meth) acryl group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. Preferably the reactive groups are (meth) acryl groups and/or (meth) acrylamides. By having these reactive groups, excellent adhesion to a polarizing plate (polarizing element) can be achieved.

In 1 embodiment, the functional group shown by X is preferably a functional group shown by Z-Y-. Here, Z represents a functional group containing at least 1 reactive group selected from the group consisting of vinyl group, (meth) acryl group, styryl group, (meth) acrylamide group, vinyl ether group, epoxy group, oxetanyl group, hydroxyl group, amino group, aldehyde group, and carboxyl group, and Y represents phenylene group or alkylene group.

As the comonomer, the following compounds can be specifically used.

The comonomer is used in an amount exceeding 0 parts by weight and less than 50 parts by weight relative to 100 parts by weight of the monomer mixture. Preferably 0.01 to less than 50 parts by weight, more preferably 0.05 to 20 parts by weight, still more preferably 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight.

< acrylic resin containing lactone ring and the like >

In another embodiment, the acrylic resin has a repeating unit including a ring structure selected from a lactone ring unit, a glutaric anhydride unit, a glutaric imide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. The repeating unit containing a ring structure may be contained in only one kind of repeating unit of the acrylic resin, or may be contained in 2 or more kinds.

The lactone ring unit is preferably represented by the following general formula (2):

in the general formula (2), R ² 、R ³ R is R ⁴ Each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom. The acrylic resin may contain only a single lactone ring unit, or R in the above general formula (2) ² 、R ³ R is R ⁴ A plurality of different lactone ring units. Acrylic resins having lactone ring units are described in, for example, japanese patent application laid-open No. 2008-181078, the description of which is incorporated herein by reference.

The glutarimide unit is preferably represented by the following formula (3):

in the general formula (3), R ¹¹ R is R ¹² Each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms, R ¹³ Represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. In the general formula (3), R is preferably ¹¹ R is R ¹² Each independently is hydrogen or methyl, R ¹³ Is hydrogen, methyl, butyl or cyclohexyl. More preferably, R ¹¹ Is methyl, R ¹² Is hydrogen, R ¹³ Is methyl. The acrylic resin may contain only a single glutarimide unit or R in the above general formula (3) ¹¹ 、R ¹² R is R ¹³ A variety of different glutarimide units. Acrylic resins having glutarimide units are described, for example, in Japanese patent application laid-open No. 2006-309033, japanese patent application laid-open No. 2006-317560, japanese patent application laid-open No. 2006-328334, japanese patent application laid-open No. 2006-337491Japanese patent application laid-open No. 2006-337492, japanese patent application laid-open No. 2006-337493, and Japanese patent application laid-open No. 2006-337569, the descriptions of which are incorporated herein by reference. In the glutaric anhydride unit, the group represented by R in the general formula (3) is removed ¹³ The above description of the glutarimide units applies in addition to the substituted nitrogen atom being an oxygen atom.

The maleic anhydride unit and the maleimide (N-substituted maleimide) unit are defined by names, and thus detailed description thereof is omitted.

The content of the repeating unit containing a ring structure in the acrylic resin is preferably 1 to 50 mol%, more preferably 10 to 40 mol%, and even more preferably 20 to 30 mol%. The acrylic resin contains a repeating unit derived from the (meth) acrylic monomer as a main repeating unit.

The second resin layer is typically formed by forming a coating film by applying an organic solvent solution of the above resin, and solidifying or thermally curing the obtained coating film. As the organic solvent, any suitable organic solvent that can dissolve or uniformly disperse the above resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone. The resin concentration of the solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. When the resin concentration is such, a uniform coating film can be formed.

The solution may be applied to any suitable substrate, preferably to a polarizing plate (polarizer). In the case of applying the solution to a substrate, it is typical to transfer the second resin layer formed on the substrate to a polarizing plate (polarizing element). The transfer is typically performed via an adhesive layer, and therefore, the second resin layer may be directly formed by applying a solution to a polarizing plate (polarizing element), omitting the adhesive layer. As a method of applying the solution, any suitable method may be employed. Specific examples thereof include roll coating, spin coating, bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).

The heating temperature for solidifying or thermally curing the coating film is preferably 100 ℃ or less, more preferably 50 to 70 ℃. When the heating temperature is in such a range, adverse effects on the polarizer can be prevented. The heating time may be, for example, 1 to 10 minutes.

The second resin layer (substantially an organic solvent solution of the above resin) may contain any appropriate additive according to the purpose. Specific examples of the additive include an ultraviolet absorber; a leveling agent; antioxidants such as hindered phenols, phosphorus, sulfur, etc.; stabilizers such as a light stabilizer, a weather stabilizer, and a heat stabilizer; reinforcing materials such as glass fibers and carbon fibers; a near infrared ray absorber; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, and the like; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, dyes, and the like; an organic filler or an inorganic filler; a resin modifier; an organic filler and an inorganic filler; a plasticizer; a slip agent; an antistatic agent; a flame retardant; etc. The kind, amount, combination, addition amount, and the like of the additives may be appropriately set according to the purpose.

H. Adhesive layer

The adhesive layer (adhesive layer 60) disposed adjacent to the second resin layer is preferably composed of a cured product of the adhesive composition. Specifically, it is preferably composed of a cured product of an active energy ray curable adhesive composition (radical polymerization curable adhesive composition) such as electron beam curability, ultraviolet curability, and visible light curability. The thickness of the adhesive layer is preferably 3 μm or less, more preferably 2 μm or less. By using such a thickness, the thickness of the polarizing plate with the retardation layer can be greatly reduced. In addition, the influence on other members caused by shrinkage that occurs when the adhesive composition forms the adhesive layer can be reduced. For example, the thickness of the adhesive layer is preferably 0.05 μm or more, more preferably 0.5 μm or more, and still more preferably 1 μm or more from the viewpoint of obtaining excellent adhesion.

Examples of the monomer component constituting the radical polymerization curable adhesive composition include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. The monomer component may be any of monofunctional radical polymerizable compounds or polyfunctional radical polymerizable compounds having 2 or more polymerizable functional groups. These radically polymerizable compounds may be used singly or in combination of 2 or more. In the present invention, (meth) acryl means acryl and/or methacryl.

The octanol/water distribution coefficient log pow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is, for example, 1.0 to 4.0, preferably 1.5 to 2.0 or more and may be 2.5 or more. By using such an adhesive composition, excellent adhesion to the second resin layer can be obtained. Also, the function (e.g., barrier function) possessed by the second resin layer can be maintained. By using such an adhesive composition, formation of an intermediate layer (compatible layer) that is formed by dissolving (compatibilizing) a part of the second resin layer in the adhesive composition for forming the adhesive layer can be suppressed when the adhesive layer is formed. Here, the octanol/water partition coefficient (logPow) is an index indicating the lipophilicity of a substance, and refers to a logarithmic value of the octanol/water partition coefficient. A logPow high may mean lipophilic. The logPow may be measured (for example, by a flask permeation method described in JIS-Z-7260), but may be calculated by calculation. In the present specification, octanol/water partition coefficient (logPow) refers to a value calculated by Chem Draw Ultra manufactured by cambridge soft corporation. The use of the adhesive composition having high hydrophobicity for the resin layer, which may be a solid or a thermosetting resin of a coating film of an organic solvent solution of the resin, suppresses the formation of the intermediate layer and provides excellent adhesion, which is an unexpected excellent effect. The presence or absence of formation of the intermediate layer can be confirmed by Scanning Electron Microscope (SEM) observation.

The logPow of the free radical polymerizable compound is shown below. For example, there may be mentioned: hydroxyethyl acrylamide (trade name "HEAA", logPow, inc; -0.56), diethylacrylamide (trade name "DEAA", manufactured by KJ Chemicals Corporation, logPow; 1.69), unsaturated fatty acid hydroxyalkyl Ester modified epsilon-caprolactone (trade name "PLACCEL FA1DDM", manufactured by Daicel Corporation, logPow; 1.06), N-vinylformamide (trade name "BEAMSET 770", manufactured by Katsumadai chemical Co., ltd., logPow; -0.25), acryloylmorpholine (trade name "ACMO", manufactured by Katsumadai chemical Co., ltd., logPow; -0.20), gamma-butyrolactone acrylate (trade name "GBLA", manufactured by Osaka organic chemical Co., ltd., logPow; 0.19), acrylic acid dimer (trade name "beta-CEA", manufactured by Daicel Corporation, logPow; 0.2), N-vinylpyrrolidone (trade name "NVP", manufactured by Japanese catalyst Co., ltd., logPow; 0.24), acetoacetoxyethyl methacrylate (trade name "AAEM", manufactured by Japanese synthetic chemical Co., ltd., logPow; 0.27), 2-hydroxyethyl acrylate (trade name "HEA", manufactured by Katsumadai organic chemical Co., ltd., logPow; 0.28), glycidyl methacrylate (trade name "Light Ester G", manufactured by Katsumadai chemical Co., ltd., logPow;0.5, manufactured by OgPow; 0.24), acetoacetoxyethyl methacrylate (trade name "AAEM", manufactured by Japanese synthetic chemical Co., ltd., logPow; 0.5; and 3.58, 6. V, 0.27) LogPow manufactured by Osaka organic chemical industries Co., ltd; 0.68 Acrylic acid (trade name "acrylic acid", logPow, mitsubishi chemical company, inc.); 0.69 Ext> triethyleneext> glycolext> diacrylateext> (ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> EGext> -ext> Aext>"ext>,ext> manufacturedext> byext> Kagakuext> chemicalext> Coext>.ext>,ext> Ltdext>.ext>,ext> LogPowext>)ext>;ext> 0.72 Ext> PEGext> 400ext> #ext> diacrylateext> (ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> EGext> -ext> Aext>"ext>,ext> LogPowext>,ext> coext> -ext> mingledext> chemicalext> Coext>.ext>,ext> Ltdext>.ext>)ext>;ext> -0.1), polypropylene glycol diacrylate (trade name "arofix M-220", manufactured by east asia synthetic company, logPow;1.68 Dicyclopentenyl acrylate (trade name "FANCRYL FA-511AS", manufactured by hitachi chemical corporation, logPow); 2.26 Butyl acrylate (trade name "butyl acrylate", logPow, mitsubishi chemical company); 2.35 1, 6-hexanediol diacrylate (trade name "LIGHT ACRYLATE 1.6.6 HX-A", manufactured by Kagaku chemical Co., ltd., logPow); 2.43 Dicyclopentanyl acrylate (trade name "FANCRYL FA-513AS", manufactured by hitachi chemical Co., ltd., log pow); 2.58 Dimethylol-tricyclodecane diacrylate (trade name "LIGHT ACRYLATE DCP-A", manufactured by Kagaku chemical Co., ltd.); 3.05 Isobornyl acrylate (trade name "LIGHT ACRYLATE IB-XA", manufactured by Kagaku chemical Co., ltd., logPow); 3.27 Neopentyl glycol hydroxypivalate acrylate adduct (trade name "LIGHT ACRYLATE HPP-A", manufactured by Kyowa Kagaku Co., ltd., logPow); 3.35 1, 9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1,9ND-A", manufactured by Kagaku chemical Co., ltd., logPow); 3.68 O-phenylphenol EO-modified acrylate (trade name "FANCRYL FA-301A", manufactured by Hitachi chemical Co., ltd.); 3.98 2-ethylhexyl Oxetane (trade name "Aron oxyetane OXT-212", manufactured by east Asia Synthesis Co., ltd., logPow); 4.24 Bisphenol-a-diglycidyl ether (trade name "JER828", log pow, mitsubishi chemical Co., ltd.); 4.76 Bisphenol a EO 6 molar modified diacrylate (trade name "FA-326A", manufactured by hitachi chemical corporation, logPow;4.84 Bisphenol a EO 4 molar modified diacrylate (trade name "FA-324A", manufactured by hitachi chemical corporation, logPow;5.15 Bisphenol a PO 2 molar modified diacrylate (trade name "FA-P320A", manufactured by hitachi chemical corporation, logPow;6.10 Bisphenol a PO 3 molar modified diacrylate (trade name "FA-P323A", manufactured by hitachi chemical corporation, logPow;6.26 Bisphenol a PO 4 molar modified diacrylate (trade name "FA-P324A", manufactured by hitachi chemical corporation, logPow;6.43 Lauryl acrylate (trade name "LIGHT ACRYLATE L-A", manufactured by co-Rong chemical Co., ltd., logPow); 6) Isostearyl acrylate (trade name "ISTA"), manufactured by osaka organic chemical industry, inc; logPow;7.46 Phenoxy diethylene glycol acrylate (trade name "P2HA", logPow, co-mings chemical company); 2.15 2-hydroxy-3-phenoxypropyl acrylate (trade name "aromix M-5700", logPow, manufactured by eastern synthetic corporation); 1.17).

When the total amount of the monomer components contained in the adhesive composition is set to 100 parts by weight, the content of the monomer components having an octanol/water partition coefficient logPow of 0.0 or less may be 30 parts by weight or less. When the total amount of the monomer components contained in the adhesive composition is set to 100 parts by weight, the content of the monomer components having an octanol/water partition coefficient logPow of 2.0 or more may be 40 parts by weight or more.

The amount of the polymerization initiator to be used for curing is, for example, 0.05 to 10% by weight based on 100% by weight of the total amount of the adhesive composition.

The curing of the adhesive composition can be performed, for example, by irradiating a coating film of the adhesive composition with active energy rays (for example, visible rays, ultraviolet rays, electron beams).

I. Image display device

The polarizing plate with the retardation layer can be applied to an image display device. Accordingly, the embodiment of the present invention also 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 are given.

Fig. 2 is a cross-sectional view schematically showing a schematic configuration of an image display panel included in the image display device according to 1 embodiment of the present invention, taking an organic EL display device as an example. The image display panel (organic EL panel) 200 has: an organic panel body 70 and a polarizing plate 100 with a retardation layer disposed on the visual recognition side thereof. The polarizing plate 100 with a retardation layer is arranged such that the first retardation layer 21 is on the organic EL panel main body 70 side with respect to the polarizer 11. Typically, the polarizing plate 100 with a retardation layer is attached to the organic EL panel body 70 by the adhesive layer 40.

The organic EL panel body 70 has a substrate 71 and an upper structural layer 72, the upper structural layer 72 including: a circuit layer including a Thin Film Transistor (TFT) or the like, an Organic Light Emitting Diode (OLED), a sealing film sealing the OLED, and the like. The upper structural layer 72 may include metal components (e.g., electrodes, sensors, wiring, metal layers). For example, in the case of using a flexible substrate (for example, a resin substrate) as the substrate 71, the obtained organic EL display device can be bent, buckled, folded, curled, or the like. The polarizing plate with a retardation layer according to the embodiment of the present invention can have excellent flexibility and bending durability, and thus can be suitably applied to such an image display device.

Examples

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The thickness, tg and Mw were measured by the following measurement methods. Unless otherwise specified, "parts" and "%" in examples and comparative examples are weight basis.

(1) Thickness of (L)

The thickness of 10 μm or less was measured by a scanning electron microscope (product name "JSM-7100F", manufactured by Japanese electronics Co., ltd.). The thickness exceeding 10 μm was measured using a digital micrometer (digital micrometer) (product name "KC-351C" manufactured by Anritsu Co., ltd.).

(2) Glass transition temperature (Tg)

The following was obtained: about 5mg of the sample (polymer) was collected, DSC measurement was performed under the following conditions, and the intermediate point glass transition temperature was calculated from the measurement results obtained.

Measurement device: TA Instruments, product name: q-2000

Temperature program: changing from 0 ℃ to 150 ℃ to 0 ℃ to 150 DEG C

Atmosphere gas: n (N) ₂ (50 mL/min)

Measurement speed: 10 ℃/min

(3) Weight average molecular weight (Mw)

The measurement was performed by Gel Permeation Chromatography (GPC), and the measurement was performed as a value in terms of standard polystyrene.

Analysis device: HLC-8120GPC manufactured by Tosoh Co., ltd

Column: manufactured by Tosoh corporation, G7000HXL+GMHXL+GMHXL

Column size: each of which is provided withTotaling 90cm

Column temperature: 40 DEG C

Flow rate: 0.8ml/min

Injection amount: 100 μl of

Eluent: tetrahydrofuran (THF)

Detector: differential Refractometer (RI)

Standard sample: polystyrene

Example 1

(production of polarizing plate)

As the thermoplastic resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) having a bar-like shape and a Tg of about 75℃was used, and one side of the resin substrate was subjected to corona treatment.

In the case of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%), acetoacetyl-modified PVA (trade name "GOHSEFIME" manufactured by Japanese chemical Co., ltd.) was used as a catalyst at 9:1 to 100 parts by weight of the PVA-based resin mixed in the above step, 13 parts by weight of potassium iodide was added, and the resultant was dissolved in water to prepare a PVA aqueous solution (coating liquid).

The PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60 ℃ to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.

The resulting laminate was uniaxially stretched to 2.4 times in the machine direction (lengthwise direction) in an oven at 130 c (air-assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40 ℃ for 30 seconds (insolubilization treatment).

Next, the concentration was adjusted so that the monomer transmittance (Ts) of the finally obtained polarizing material became a desired value in a dyeing bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ℃ and immersed for 60 seconds (dyeing treatment).

Then, the resultant mixture was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide with 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40℃for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4 wt% and potassium iodide concentration: 5 wt%) at a liquid temperature of 70 ℃ and uniaxially stretched (in-water stretching treatment) between rolls having different peripheral speeds so that the total stretching ratio became 5.5 times in the longitudinal direction.

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20 ℃.

Thereafter, it was dried in an oven maintained at about 90 ℃ and was brought into contact with a SUS-made heating roller (drying shrinkage treatment) having a surface temperature maintained at about 75 ℃.

Thus, a polarizing element having a thickness of about 5 μm was formed on the resin substrate.

An HC-TAC film was attached to the surface of the obtained polarizer (the surface opposite to the resin substrate) as a visual recognition side protective layer by means of an ultraviolet curable adhesive. The HC-TAC film was a film in which a hard coat layer (thickness 7 μm) was formed on a cellulose Triacetate (TAC) film (thickness 25 μm), and was bonded so that the TAC film became the polarizer side. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of an HC-TAC film/polarizer. The shrinkage of the HC-TAC film after 240 hours at 85℃was 0.03%.

(formation of the second resin layer)

99.0 parts by weight of methyl methacrylate (manufactured by MMA, FUJIFILM Wako Pure Chemical Corporation, trade name: methyl methacrylate monomer), 1.0 parts by weight of a monomer of the general formula (1 e), and 0.2 parts by weight of a polymerization initiator (manufactured by FUJIFILM Wako Pure Chemical Corporation, trade name: 2,2' -azobis (isobutyronitrile)) were dissolved in 100 parts by weight of toluene. Then, the mixture was heated to 70℃under a nitrogen atmosphere and polymerized for 5.5 hours to obtain copolymer 1 (solid content concentration: 50% by weight). The Tg of copolymer 1 was 105℃and the Mw was 85000.

To 70 parts (in terms of solid content) of the obtained copolymer 1 (boric acrylic resin), 22.5 parts (in terms of solid content) of trimethylolpropane adduct of toluene diisocyanate (trade name "CORONATE L" manufactured by eastern co., ltd.) and 7.5 parts (in terms of solid content) of trimethylolpropane adduct of hexamethylene diisocyanate (trade name "TAKENATE D N" manufactured by Mitsui chemical Co., ltd.) were added as isocyanate compounds to obtain a mixture. The mixture was dissolved in 80 parts of a mixed solvent of ethyl acetate/cyclopentanone (70/30) to obtain a resin solution (20%). The resin solution was applied to the polarizer-side surface of the polarizing plate obtained in the above using a wire bar, and the coated film was dried at 60 ℃ for 5 minutes to form a second resin layer (thickness 0.4 μm) in the form of a solid product of the coated film of the organic solvent solution of the resin.

(production of retardation film constituting the first retardation layer)

The polymerization was carried out using a batch polymerization apparatus comprising 2 vertical reactors equipped with stirring blades and a reflux condenser controlled to 100 ℃. Adding bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl]29.60 parts by mass (0.046 mol) of methane, 29.21 parts by mass (0.200 mol) of Isosorbide (ISB), 42.28 parts by mass (0.139 mol) of Spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC) and 1.19X10 of calcium acetate monohydrate as a catalyst ^-2 Parts by mass (6.78X10) ^-5 mol). After the reduced pressure nitrogen substitution was performed in the reactor, the reactor was heated by a heat medium, and stirring was started at the time when the internal temperature became 100 ℃. After 40 minutes from the start of the temperature rise, the internal temperature was brought to 220℃and the pressure was reduced while maintaining the temperature, and after reaching 220℃the internal temperature was brought to 13.3kPa for 90 minutes. The phenol vapor produced as a by-product during the polymerization reaction was introduced into a reflux condenser at 100℃to return a certain amount of the monomer components contained in the phenol vapor to the reactor, and the non-condensed phenol vapor was introduced into a condenser at 45℃to be recovered. After nitrogen gas was introduced into the 1 st reactor and the pressure was temporarily returned to the atmospheric pressure, the oligomerization reaction liquid in the 1 st reactor was transferred to the 2 nd reactor. Then, the temperature rise and pressure reduction in the 2 nd reactor were started, and the internal temperature was 240℃and the pressure was 0.2kPa for 50 minutes. Thereafter, polymerization is carried out until a predetermined stirring power is reached. Introducing nitrogen gas into the reactor to recover the gas pressure at the moment of reaching the preset power, extruding the produced polyester carbonate resin into water, and feeding the wire materialCutting to obtain granules.

After the obtained polyester-carbonate resin (pellet) was vacuum-dried at 80℃for 5 hours, a strip-shaped resin film having a thickness of 135 μm was produced using a film-forming apparatus equipped with a single screw extruder (manufactured by Toshiba machinery Co., ltd., barrel set temperature: 250 ℃), a T die (width: 200mm, set temperature: 250 ℃), a cooling roll (set temperature: 120 to 130 ℃) and a winder. The obtained resin film was stretched in the width direction at a stretching temperature of 133℃and a stretching ratio of 2.8 times to obtain a retardation film having a thickness of 48. Mu.m. The Re (550) of the obtained retardation film was 141nm, re (450)/Re (550) was 0.82, and the Nz coefficient was 1.12.

(production of liquid Crystal alignment solid layer constituting second phase Difference layer)

A liquid crystal coating liquid was prepared by dissolving 20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (A) (wherein numerals 65 and 35 in the formula represent mol% of monomer units, and the polymer is represented by a block polymer for convenience: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal (manufactured by BASF corporation: paliocolarrorLC 242) exhibiting a nematic liquid crystal phase, and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Inc.: irgacure 907) in 200 parts by weight of cyclopentanone. Then, the coating liquid was applied to the PET substrate subjected to the vertical alignment treatment by a bar coater, and then heated and dried at 80 ℃ for 4 minutes, thereby aligning the liquid crystal. The liquid crystal layer was irradiated with ultraviolet light, and the liquid crystal layer was cured, whereby a liquid crystal alignment solidified layer (thickness 3 μm) exhibiting refractive index characteristics of nz > nx=ny was formed on the substrate.

(preparation of ultraviolet-curable adhesive 1)

Isostearyl acrylate (trade names "ISTA", logPow, manufactured by osaka organic chemical industries, inc.); 7.46) 20 parts of lauryl acrylate (manufactured by Kyowa Kagaku Co., ltd., trade name "LIGHT ACRYLATE L-A", logPow; 6) 10 parts of 1, 9-nonanediol diacrylate (manufactured by Kyowa Kagaku Co., ltd., trade name "LIGHT ACRYLATE 1,9ND-A", logPow; 3.68) 10 parts of diethylacrylamide (manufactured by KJ Chemicals Corporation, trade name "DEAA", logPow; 1.69)) 20 parts of unsaturated fatty acid hydroxyalkyl ester modified epsilon-caprolactone (manufactured by Daicel Corporation, trade name "PLACCEL FA DDM", logPow; 1.06) 20 parts of acryloylmorpholine (manufactured by Kyowa Co., trade name "ACMO", logPow; 0.20) 20 parts of photopolymerization initiator (manufactured by BASF corporation, trade name "Irgacure") 3 parts were blended to prepare ultraviolet curable adhesive 1.

(production of polarizing plate with retardation layer)

The liquid crystal alignment layer was bonded to one side of the retardation film using the ultraviolet curable adhesive 1. Specifically, the ultraviolet-curable adhesive was applied to the retardation film so that the thickness after curing became 1.5. Mu.m, and the cumulative light amount became 900mJ/cm under a nitrogen atmosphere ² The liquid crystal alignment layer is bonded to one side of the retardation film via an adhesive layer.

Next, the polarizing plate was bonded to the other side of the retardation film using the ultraviolet curable adhesive 1. Specifically, the ultraviolet-curable adhesive was applied to the retardation film so that the thickness after curing became 2. Mu.m, and the cumulative light amount became 900mJ/cm under a nitrogen atmosphere ² The second resin layer formed on the polarizing plate is bonded to the retardation film by being irradiated with ultraviolet rays and cured.

Then, an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm was formed on the surface of the liquid crystal alignment layer to obtain a polarizing plate with a retardation layer.

Example 2

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the below-described ultraviolet curable adhesive 2 was used instead of the ultraviolet curable adhesive 1 when the liquid crystal alignment solid layer was bonded to the retardation film.

(preparation of ultraviolet-curable adhesive 2)

An ultraviolet curable adhesive 2 was prepared by mixing 25 parts of polypropylene glycol diacrylate (trade name "ARONIX M-220", logPow; 1.68), 40 parts of acryloylmorpholine (trade name "ACMO", logPow; 0.20 ", manufactured by Xinghu Co., ltd.), 35 parts of hydroxyethylacrylamide (trade name" HEAA ", logPow; 0.56", manufactured by Xinghu Co., ltd.) and 3 parts of a photopolymerization initiator (trade name "Irgacure907", manufactured by BASF).

Example 3

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the below-described ultraviolet curable adhesive 3 was used instead of the ultraviolet curable adhesive 1 when the liquid crystal alignment solid layer was bonded to the retardation film.

(preparation of ultraviolet-curable adhesive 3)

A UV-curable adhesive 3 was prepared by mixing 30 parts of 1, 9-nonanediol diacrylate (manufactured by Kyowa chemical Co., ltd., trade name "LIGHT ACRYLATE 1,9ND-A", logPow; 3.68), 50 parts of neopentyl glycol hydroxypivalate acrylate adduct (manufactured by Kyowa chemical Co., ltd., trade name "LIGHT ACRYLATE HPP-A", logPow; 3.35), 15 parts of 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Toyama Synthesis Co., ltd., trade name "ARONIX M-5700", logPow; 1.17), 5 parts of hydroxyethylacrylamide (manufactured by KO Co., ltd., trade name "HEAA", logPow; 0.56) and 3 parts of a photopolymerization initiator (manufactured by BASF Co., ltd., trade name "Irgacure 907").

Example 4

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that the below-described ultraviolet curable adhesive 4 was used instead of the ultraviolet curable adhesive 1 when the liquid crystal alignment solid layer was bonded to the retardation film.

(preparation of ultraviolet-curable adhesive 4)

An ultraviolet curable adhesive 4 was prepared by mixing 40 parts of 1, 9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1,9ND-A", logPow; 3.68) manufactured by Kyowa chemical Co., ltd., trade name "ACMO", logPow; -0.20) 40 parts of acryloylmorpholine (trade name "ACMO", logPow; -0.20), 20 parts of hydroxyethylacrylamide (trade name "HEAA", logPow; -0.56) and 3 parts of a photopolymerization initiator (trade name "Irgacure907", manufactured by BASF).

Example 5

A polarizing plate with a retardation layer was obtained in the same manner as in example 4, except that a third resin layer (thickness 0.4 μm) was provided between the liquid crystal alignment layer and the acrylic adhesive layer (surface of the liquid crystal alignment layer) by the same method as the formation of the second resin layer.

Example 6

A polarizing plate with a retardation layer was obtained in the same manner as in example 4, except that the ultraviolet-curable adhesive 5 shown below was used instead of the ultraviolet-curable adhesive 1 when the polarizing plate was bonded to the retardation film.

(preparation of ultraviolet-curable adhesive 5)

An ultraviolet curable adhesive 5 was prepared by mixing 20 parts of 1, 9-nonanediol diacrylate (manufactured by Kyowa chemical Co., ltd., trade name "LIGHT ACRYLATE 1,9ND-A", logPow; 3.68), 40 parts of phenoxydiglycol acrylate (manufactured by Kyowa chemical Co., ltd., trade name "P2HA", logPow; 2.15), 10 parts of diethylacrylamide (manufactured by KJ Chemicals Corporation, trade name "DEAA", logPow; 1.69), 30 parts of hydroxyethylacrylamide (manufactured by KO. Chemie, trade name "HEAA", logPow; -0.56) and 3 parts of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907").

Example 7

A polarizing plate with a retardation layer was obtained in the same manner as in example 2, except that an acrylic adhesive (thickness 5 μm) was used instead of the ultraviolet-curable adhesive 1 when the polarizing plate was bonded to the retardation film.

Comparative example 1

A polarizing plate with a retardation layer was obtained in the same manner as in example 3, except that the second resin layer was not provided and an acrylic adhesive (thickness: 5 μm) was used to bond the polarizing plate to the retardation film.

Comparative example 2

A polarizing plate with a retardation layer was obtained in the same manner as in example 1, except that an acrylic adhesive (thickness: 5 μm) was used instead of the ultraviolet-curable adhesive 1 when the polarizing plate was bonded to the retardation film, and that an ultraviolet-curable adhesive 6 shown below was used instead of the ultraviolet-curable adhesive 1 when the liquid crystal alignment layer was bonded to the retardation film.

(preparation of ultraviolet-curable adhesive 6)

An ultraviolet curable adhesive 6 was prepared by mixing 40 parts of unsaturated fatty acid hydroxyalkyl ester modified ε -caprolactone (manufactured by Daicel Corporation, trade name "PLACCEL FA DDM", logPow; 1.06), 30 parts of acryloylmorpholine (manufactured by Xinghui, trade name "ACMO", logPow; -0.20), 30 parts of hydroxyethylacrylamide (manufactured by Xinghui, trade name "HEAA", logPow; -0.56) and 3 parts of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907").

The following evaluations were performed for each of the examples and comparative examples. The evaluation results are summarized in table 1.

< evaluation >

1. Storage modulus

The ultraviolet curable adhesives for forming the first resin layer of each of examples and comparative examples were sandwiched between 2 glasses, and the thickness was adjusted to be 100 μm, and after irradiation with active energy rays under the conditions described below, the films of the first resin layer were produced by separating them from the glasses.

(irradiation conditions of active energy ray)

Visible light irradiation device (gallium-enclosed metal halide lamp): fusion UV Systems manufactured by Inc

Light HAMMER10 valve: v valve

Peak illuminance: 1600mW/cm ²

Cumulative exposure to light: 1000/mJ/cm ² (wavelength 380-440 nm)

The storage modulus of the film of the first resin layer obtained was measured at 25℃and 100℃by a dynamic viscoelasticity measuring apparatus (product name "RSA" manufactured by TA Instruments Co.). The measurement conditions were as follows.

(measurement conditions)

Sample size: width 10mm and length 30mm

Clamp distance 20mm

Measurement mode: stretching

Frequency: 1Hz

Temperature: -40-180 DEG C

Temperature increase rate: 10 ℃/min

Hast assay

The obtained polarizing plate with the retardation layer was subjected to a HAST test, which is an acceleration test concerning durability under a high-temperature and high-humidity environment. Specifically, a test sample in which a polarizing plate with a retardation layer (cut into 50mm×50 mm) was bonded to the surface of the overcoat layer of a metal film of a test plate produced as described below was heated and humidified by placing the test sample in an oven controlled at 110 ℃ and 85% rh for 36 hours, and the state of the heated and humidified test sample was visually observed and evaluated according to the following criteria. The results are shown in Table 1.

(production of test plate)

A silver nanowire solution (isopropyl alcohol (IPA) solution having a diameter of 115nm, a length of 20 μm to 50 μm, and a solid content of 0.5%) was applied to one surface of a 50 μm polyethylene terephthalate (PET) film with a wire rod so that the wet film thickness became 15 μm, and the film was dried in an oven at 100℃for 5 minutes to form a silver nanowire coating film. Next, an overcoat solution (solid content concentration: about 1%) containing 99 parts of methyl isobutyl ketone (MIBK), 1 part of pentaerythritol tetraacrylate (PETA), and 0.03 parts of a photopolymerization initiator (product name "Irgacure 907", manufactured by BASF corporation) was applied to the surface of the silver nanowire coating film using a wire bar so that the wet film thickness became 10 μm, and dried in an oven at 100 ℃ for 5 minutes. Subsequently, the overcoating film was cured by irradiation with active energy rays, and a metal film having a structure of a PET film, a silver nanowire layer, and an overcoating layer (thickness 100 nm) was produced. The metal thin film was bonded to a glass plate having a thickness of 0.5mm using an adhesive (15 μm), to obtain a test plate of metal thin film/adhesive/glass plate.

(evaluation criterion)

Very good (5): no corrosion was confirmed at all

Good (4): only at the end of the polarizing plate with the retardation layer was observed a slight discoloration

Allowable (3): corrosion, peeling and the like were confirmed within 1mm from the edge of the polarizing plate with the retardation layer

Poor (2): corrosion, peeling and the like were confirmed within 3mm from the edge of the polarizing plate having the retardation layer

Very bad (1): corrosion, peeling, and the like were confirmed in a range from the end edge of the polarizing plate with the retardation layer to more than 3mm

TABLE 1

In each example, occurrence of corrosion in the surface excluding the range of 1mm or less from the edge, peeling of the laminate, and the like was suppressed.

Industrial applicability

The polarizing plate with a retardation layer of the present invention can be suitably used for an image display device (typically, a liquid crystal display device or an organic EL display device).

Claims

1. A polarizing plate with a retardation layer, comprising:

a first phase difference layer having a first main surface and a second main surface facing each other;

a polarizer disposed on the first principal surface side of the first retardation layer;

a first resin layer disposed on the second principal surface side of the first retardation layer; and

A second resin layer disposed between the polarizer and the first retardation layer,

the first retardation layer is formed of a stretched film of a resin film and satisfies the relationship Re (450) < Re (550),

the first resin layer has a storage modulus at 100deg.C of 1.0X10 ⁶ The pressure of the mixture is more than Pa,

the second resin layer has a thickness of 1 μm or less and comprises a resin and an isocyanate compound,

wherein Re (450) and Re (550) are in-plane retardation measured at 23℃by light having a wavelength of 450nm and light having a wavelength of 550nm, respectively.

2. The polarizing plate with a retardation layer according to claim 1, comprising an adhesive layer disposed between the first retardation layer and the polarizing element and adjacent to the second resin layer, wherein the adhesive layer is composed of a cured layer of an adhesive composition, and the octanol/water distribution coefficient log pow calculated by a weighted average of mole fractions of monomer components contained in the adhesive composition is 1.5 to 4.0.

3. The polarizing plate with a retardation layer as claimed in claim 1, wherein the second resin layer comprises a resin having a glass transition temperature of 85 ℃ or higher and a weight average molecular weight Mw of 50000 or higher and less than 500000, and the content of the resin in the second resin layer is 50% by weight or more and 90% by weight or less.

4. The polarizing plate with a retardation layer as claimed in claim 1, wherein the isocyanate compound contained in the second resin layer contains at least 1 selected from toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives thereof, and the content of the isocyanate compound in the second resin layer is 10% by weight or more and 50% by weight or less.

5. The polarizing plate with a retardation layer according to claim 1, which has a second retardation layer disposed on the second main surface side of the first retardation layer and having refractive index characteristics exhibiting a relationship of nz > nx=ny,

the first resin layer is disposed between the first phase difference layer and the second phase difference layer.

6. The polarizing plate with a retardation layer as claimed in claim 5, wherein the first resin layer functions as an adhesive layer.

7. The polarizing plate with a retardation layer as claimed in claim 1, wherein the storage modulus of the first resin layer at 100 ℃ is 1.0 x 10 ⁸ Pa or more.

8. The polarizing plate with a retardation layer as claimed in claim 1, wherein the storage modulus of the first resin layer at 25 ℃ is 1.0 x 10 ⁹ Pa or more.

9. The polarizing plate with a retardation layer according to claim 1, wherein a ratio of storage modulus G '(25) at 25 ℃ to storage modulus G' (100) at 100 ℃, i.e., G '(25)/G' (100), of the first resin layer is less than 10.0.

10. The polarizing plate with a retardation layer as claimed in claim 1, wherein the first retardation layer contains a resin comprising at least 1 kind of bonding group selected from the group consisting of a carbonate bond and an ester bond and at least 1 kind of structural unit selected from the group consisting of a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II), and has positive refractive index anisotropy,

11. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 10.