KR20240095215A - Polarizer and image display device with phase contrast layer - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer having excellent durability even under harsh high-temperature and high-humidity environments. A polarizing plate with a retardation layer according to an embodiment of the present invention includes a first retardation layer having a first main surface and a second main surface opposing each other, a polarizer disposed on the first main surface side of the first retardation layer, and the second main surface. 1 Comprising a first layer disposed on the second main surface side of the retardation layer, wherein the first retardation layer is composed of a stretched resin film, and satisfies the relationship of Re (450) < Re (550), The first layer is a resin layer and has a shear fracture strength of 85 MPa or more. Here, Re(450) and Re(550) are the in-plane retardation measured with light with a wavelength of 450 nm and 550 nm at 23°C, respectively.

Description

Polarizer and image display device with phase contrast layer

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

In recent years, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices) are rapidly becoming popular. Polarizing plates and retardation plates are typically used in image display devices. In practical terms, a polarizing plate with a retardation layer that integrates a polarizing plate and a retardation plate is widely used (for example, patent document 1). In recent years, with the spread of the use of image display devices, there has been a demand for improvement in various performances also for polarizing plates with a retardation layer. For example, a polarizing plate with a retardation layer may be required to have durability under harsh high-temperature, high-humidity environments that was not required in the past.

Japanese Patent Publication No. 3325560

The present invention was made to solve the above-described conventional problems, and its main purpose is to provide a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature, high-humidity environment.

A polarizing plate with a retardation layer according to an embodiment of the present invention includes a first retardation layer having a first main surface and a second main surface opposing each other, a polarizer disposed on the first main surface side of the first retardation layer, and the second main surface. 1 comprising a first layer disposed on the second main surface side of the retardation layer, wherein the first retardation layer is composed of a stretched resin film and satisfies the relationship of Re (450) < Re (550), The first layer is a resin layer, and the shear fracture strength is more than 85MPa.

A polarizing plate with a retardation layer according to another embodiment of the present invention includes a first retardation layer having a first main surface and a second main surface opposing each other, a polarizer disposed on the first main surface side of the first retardation layer, and It includes a first layer disposed on the second main surface side of the first retardation layer, and a second layer disposed on the first main surface side of the first retardation layer, wherein the first retardation layer is a stretched film of a resin film. It satisfies the relationship of Re (450) < Re (550), the first layer is a resin layer and has a shear fracture strength of 60 MPa or more, and the second layer is a resin layer and has a shear fracture strength of 60 MPa or more.

Here, Re(450) and Re(550) are the in-plane retardation measured with light with a wavelength of 450 nm and 550 nm at 23°C, respectively.

In one embodiment, Re (550) of the first retardation layer is 100 nm to 200 nm, and the angle formed between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40 ° to 50 ° or 130 ° to 140 °. It is °.

In one embodiment, the polarizing plate with a retardation layer includes a second retardation layer disposed on the second main surface side of the first retardation layer and having a refractive index characteristic showing the relationship nz>nx=ny, and The first layer is disposed between the first phase difference layer and the second phase difference layer.

In one embodiment, the first layer functions as an adhesive layer.

In one embodiment, the first phase difference layer includes at least one bonding group selected from the group consisting of a carbonate bond and an ester bond, a structural unit represented by the following general formula (1), and a structure represented by the following general formula (2) It contains a resin that contains at least one structural unit selected from the group consisting of the unit and has positive refractive index anisotropy:

In general formulas (1) and (2), R ¹ to R ³ are each independently a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R ⁴ to R ⁹ are each independently hydrogen. Atom, substituted or unsubstituted alkyl group with 1 to 10 carbon atoms, substituted or unsubstituted aryl group with 4 to 10 carbon atoms, substituted or unsubstituted acyl group with 1 to 10 carbon atoms, substituted or unsubstituted alkoxy group with 1 to 10 carbon atoms, substituted or an 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, or a substituent. It has a silicon atom, a halogen atom, a nitro group, or a cyano group; However, R ⁴ to R ⁹ may be the same or different from each other, and at least two neighboring groups among R ⁴ to R ⁹ may be bonded to each other to form a ring.

In one embodiment, the polarizing plate with a retardation layer includes a protective layer disposed on a side opposite to the first retardation layer of the polarizer, and the shrinkage rate of the protective layer after being placed in an environment at 85° C. for 240 hours is 0.05%. It is less than.

In one embodiment, the protective layer is composed of a triacetylcellulose film or a cyclic olefin-based resin film.

According to another aspect of the present invention, an image display device is provided. This image display device is provided with the above-described polarizing plate with a retardation layer.

According to an embodiment of the present invention, a polarizing plate with a retardation layer having excellent durability even under a harsh high-temperature and high-humidity environment can be realized.

1 is a schematic cross-sectional view showing the schematic configuration of a polarizing plate with a retardation layer according to a first embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to make the explanation clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiment, but are only examples and do not limit the interpretation of the present invention. In addition, in the drawings, identical or equivalent elements are given the same reference numerals, and overlapping descriptions may be omitted.

(Definition of terms and symbols)

The definitions of terms and symbols in this specification are as follows.

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

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

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane retardation of the film measured with light with a wavelength of λnm at 23°C. For example, 'Re(450)' is the in-plane retardation of the film measured with light with a wavelength of 450 nm at 23°C. Re(λ) can be obtained by the formula: Re=(nx-ny)×d, when the thickness of the film is d(nm).

(3) Phase difference in the thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction of the film measured with light with a wavelength of λnm at 23°C. For example, 'Rth(450)' is the phase difference in the thickness direction of the film measured with light with a wavelength of 450 nm at 23°C. Rth (λ) can be obtained by the formula: Rth = (nx-nz) × d, when the thickness of the film is d (nm).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When referring to an angle in this specification, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

A. Polarizer with phase contrast layer

1 is a schematic cross-sectional view showing the schematic configuration of a polarizing plate with a retardation layer according to a first embodiment of the present invention. The polarizing plate 100 with a retardation layer includes a first retardation layer 21 having a first main surface 21a and a second main surface 21b facing each other, and a first main surface 21a of the first retardation layer 21. It includes a polarizing plate 10 disposed on the side, a first layer 31, a second retardation layer 22, and an adhesive layer 40 disposed on the second main surface 21b side of the first retardation layer 21. do. The polarizing plate 10 includes a polarizer 11 and a protective layer 12 in this order from the first retardation layer 21 side. No protective layer is disposed between the polarizer 11 and the first retardation layer 21, and the first retardation layer 21 is disposed adjacent to the polarizer 11 to function as a protective material for the polarizer 11. You can. The polarizing plate 100 with a retardation layer is typically arranged so that the polarizer 11 is on the viewing side rather than the first retardation layer 21 in an image display device. The polarizing plate 100 with a retardation layer can be obtained, for example, by laminating the polarizing plate 10 obtained by laminating the polarizer 11 and the protective layer 12, and other layers.

Fig. 2 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that the second layer 32 is provided on the first main surface 21a of the first phase difference layer 21. Specifically, the polarizing plate 100 with a retardation layer further includes the second layer 32 disposed between the polarizing plate 10 (polarizer 11) and the first retardation layer 21.

In the illustrated example, the polarizer 10 includes a polarizer 11 and a protective layer 12 disposed on one side of the polarizer 11, but in addition, a second protection layer is disposed on the other side of the polarizer 11. It may contain layers. Additionally, the polarizing plate 10 includes a polarizer 11 and a protective layer 12, but the protective layer 12 may be omitted.

The first retardation layer 21 is composed of a stretched resin film and satisfies the relationship Re(450)<Re(550). Re(550) of the first phase difference layer 21 is typically 100 nm to 200 nm. The angle formed by 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°, and even more preferably 44°. -46°, 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°.

Each member constituting the polarizing plate with a retardation layer can be laminated through any suitable adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. For example, the protective layer 12 is bonded to the polarizer 11 through an adhesive layer (preferably using an active energy ray-curable adhesive). The thickness of the adhesive layer is preferably 0.4 μm or more, more preferably 0.4 μm to 3.0 μm, and still more preferably 0.6 μm to 2.2 μm. For example, the first retardation layer 20 is bonded to the polarizing plate 10 (polarizer 11) via an adhesive layer (for example, an acrylic adhesive). The thickness of the adhesive layer is preferably 1 μm to 10 μm.

By the adhesive layer 40 disposed on the second main surface 21b side of the first retardation layer 21, for example, the polarizer 100 with a retardation layer can be attached to an image display panel included in the image display device. . 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, a release liner is practically bonded to the surface of the adhesive layer 40. The release liner can be temporarily applied until the polarizer with a retardation layer is ready for use. By using a release liner, for example, the adhesive layer 40 is protected and roll formation of a polarizing plate with a retardation layer becomes possible.

The first layer 31 and the second layer 32 are resin layers. Specifically, the first layer 31 and the second layer 32 may each be a hardened resin layer, a solidified resin layer, or a layer containing a combination of these. It is preferable that the first layer 31 and the second layer 32 are each disposed in direct contact with the first phase difference layer 21 (formed directly on the first phase difference layer 21). In one embodiment, the first layer 31 is an adhesive layer that adheres the first retardation layer 21 and a layer disposed adjacent to the first retardation layer 21 (e.g., the second retardation layer 22). It can function as In addition, adjacent includes not only directly neighboring but also adjacent through an adhesive layer.

The shear fracture strength of the second layer 32 is preferably 60 MPa or more and 200 MPa or less, and more preferably 80 MPa or more and 120 MPa or less.

As shown in FIG. 1, in a form in which the polarizing plate 100 with a retardation layer does not include the second layer 32 (a form in which the polarizing plate 10 and the first retardation layer 21 are disposed adjacent to each other), the first The shear fracture strength of the layer 31 exceeds 80 MPa, preferably 85 MPa or more, and more preferably 90 MPa or more. On the other hand, the shear fracture strength of the first layer 31 is preferably 200 MPa or less.

As shown in FIG. 2, in the form where the polarizing plate 100 with a retardation layer includes the second layer 32, the shear breaking strength of the first layer 31 is 40 MPa or more, preferably 50 MPa or more, More preferably, it is 60 MPa or more. On the other hand, the shear fracture strength of the first layer 31 is preferably 200 MPa or less, may be less than 85 MPa, or may be 80 MPa or less.

By providing the first layer, or the first layer and the second layer, a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature, high-humidity environment can be realized. Specifically, it is possible to realize a polarizing plate with a retardation layer in which cracking and peeling are suppressed even in a harsh high-temperature, high-humidity environment. Details are as follows. Since the first retardation layer used in the embodiment of the present invention exhibits extremely excellent circular polarization characteristics, a polarizing plate with a retardation layer (circularly polarizing plate) having an extremely excellent anti-reflection function can be realized. In addition, by using such a first phase difference layer in combination with a second phase difference layer whose refractive index characteristic, which will be described later, shows the relationship nz>nx=ny, wide viewing angle with anti-reflection function becomes possible. On the other hand, since the stretched film of the resin film constituting the first retardation layer has large heat shrinkage and a high water absorption rate, reliability in a high temperature and high humidity environment may be insufficient, and in addition, recent studies on characteristics In harsh high-temperature, high-humidity environments that are becoming new standards, cracks and/or peeling may occur. According to an embodiment of the present invention, by providing the first layer, or the first layer and the second layer, the excellent characteristics of the first retardation layer are maintained, and the polarizer with a retardation layer as a whole has durability and reliability under a harsh high temperature and high humidity environment. can be significantly improved. As a result, it is possible to realize a polarizing plate with a retardation layer in which cracking and peeling are suppressed even in a harsh high-temperature and high-humidity environment. In addition, the above mechanism is a guess, and the mechanism does not limit or constrain the embodiments of the present invention.

The refractive index characteristic of the second retardation layer 22, which may be included in the polarizing plate with a retardation layer, typically shows the relationship of nz>nx=ny. By providing such a phase difference layer, reflection in the oblique direction can be prevented satisfactorily, and wide viewing angle of the anti-reflection function becomes possible.

The polarizing plate with a retardation layer may include an additional retardation layer (not shown). The optical properties (eg, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the additional retardation layer may be appropriately set depending on the purpose.

The polarizing plate with a retardation layer may be sheet-shaped or elongated. In this specification, 'elongated shape' means an elongated shape with a sufficiently long length relative to the width, and includes, for example, an elongated shape whose length is 10 or more times the width, preferably 20 times or more. A long polarizing plate with a retardation layer can be wound into a roll.

B. Polarizer

As the polarizer 11, any suitable polarizer can be employed. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, with iodine or dichroic (II) Examples include those that have been dyed and stretched with dichroic substances such as dyes, and polyene-based oriented films such as dehydrated PVA products and dehydrochloric acid-treated polyvinyl chloride products. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used because it has excellent optical properties.

The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment or may be performed while dyeing. Additionally, it may be dyed after stretching. If necessary, swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. are performed on the PVA-based film. For example, by immersing the PVA-based film in water and washing it before dyeing, it is possible to clean the surface of the PVA-based film from contamination and anti-blocking agents, as well as swelling the PVA-based film to prevent staining, etc.

Specific examples of the polarizer obtained by using the above-mentioned two or more layered laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and PVA coated on the resin substrate. A polarizer obtained by using a laminated body with a resin layer can be mentioned. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by applying to the resin substrate is, for example, applied by applying a PVA-based resin solution to a resin substrate, drying it, and forming a PVA-based resin layer on the resin substrate, Obtaining a laminate of a resin substrate and a PVA-based resin layer; It can be produced by stretching and dyeing the laminate and using the PVA-based resin layer as a polarizer. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. Stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. Additionally, stretching, if necessary, may further include air stretching the laminate at a high temperature (eg, 95°C or higher) before stretching in an aqueous boric acid solution. In addition, in this embodiment, the laminate is preferably subjected to dry shrinkage treatment to shrink the laminate by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of this embodiment includes performing aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment, and dry shrink treatment on the laminate in this order. By introducing auxiliary stretching, even when applying PVA on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA and achieve high optical properties. Moreover, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process can be prevented, making it possible to achieve high optical properties. I do it. In addition, when the PVA-based resin layer is immersed in a liquid, the disruption of the polyvinyl alcohol molecule orientation and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical properties of the polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Additionally, optical properties can be improved by shrinking the laminate in the width direction through dry shrinkage treatment. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer of the polarizer), or may be applied to the peeling surface where the resin substrate is peeled from the resin substrate/polarizer laminate, or to the peeling surface. It may be used by laminating any appropriate protective layer depending on the purpose on the side opposite to the above. Details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent Application Publication No. 647055. The entire descriptions 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 especially preferably 5 μm or less. The lower limit of the thickness of the polarizer may be, for example, 1 μm. If the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good external appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single 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 even 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 suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that become the main component of the film include cellulose-based resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polyester. Transparent resins such as sulfone-based, polystyrene-based, cyclic olefin-based (eg, polynorbornene-based), polyolefin-based, (meth)acrylic-based, and acetate-based resins can be mentioned. Additionally, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition to these, for example, glassy polymers such as siloxane polymers can also be mentioned. Additionally, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, isobutene and N- A resin composition containing an alternating copolymer containing methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition.

The shrinkage rate of the protective layer 12 after being left in an environment at 85°C for 240 hours is preferably less than 0.05%, more preferably 0.04% or less, and still more preferably 0.03% or less. The smaller the shrinkage rate, the more desirable it is, and its lower limit may be, for example, 0.01%. If the shrinkage rate is within this range, cracking of the polarizer and peeling of the polarizer and the retardation layer in a harsh high-temperature, high-humidity environment can be better suppressed. The protective layer 12 is preferably comprised of a triacetylcellulose (TAC) film or a cyclic olefin resin film. The TAC film and the cyclic olefin resin film are preferably formed by extrusion or casting, and do not include stretching during film formation. As a result, since the residual stress is small, the desired shrinkage rate can be achieved.

The polarizing plate with a retardation layer according to the embodiment of the present invention is typically placed on the viewer's side of the image display device, and the protective layer 12 is placed on the viewer's side. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat (HC) treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as needed. Additionally, the protective layer 12 may be treated, as necessary, to improve visibility when viewed through polarized sunglasses (typically, imparting an (other) circular polarization function or imparting an ultra-high phase difference. ) may be implemented. By performing such processing, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can also be suitably applied to 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. In addition, when surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

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

D. First phase contrast layer

D-1. Characteristics of the first phase difference layer

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

The first phase difference layer satisfies the relationship of Re (450) < Re (550) as described above, and preferably further satisfies the relationship of Re (550) < Re (650). That is, the first phase difference layer exhibits wavelength dependence of inverse dispersion in which the phase difference value increases depending on the wavelength of the measurement light. Re(450)/Re(550) of the first phase difference layer is, for example, greater than 0.5 and less than 1.0, 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, and more preferably 1.03 to 1.1.

Since the first phase difference layer has an in-plane phase difference as described above, it has the relationship nx>ny. The first retardation layer exhibits any suitable refractive index characteristic as long as it has the relationship nx>ny. The refractive index characteristics of the first phase contrast layer typically exhibit the relationship of nx>ny≥nz. Additionally, here, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny < nz, within a range that does not impair the effect of the present invention. The Nz coefficient of the first phase difference 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 this relationship, when a polarizing plate with a retardation layer is used in an image display device, very excellent reflected color can be achieved.

The thickness of the first phase difference layer can be set to function most appropriately as a λ/4 plate. In other words, the thickness can be set so 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 first retardation layer has a shrinkage rate in the slow axis direction when heated at 80°C to 125°C for up to 180 minutes, for example, 4% or less, preferably 3.5% or less, and more preferably 3% or less. . The smaller the shrinkage rate, the more desirable it is, and its lower limit may be, for example, 0.5%. If the shrinkage rate of the first phase difference layer is within this range, cracks under severe high-temperature, high-humidity environments can be better suppressed.

The breaking elongation of the stretched film constituting the first retardation layer is preferably 200% or more, more preferably 210% or more, further preferably 220% or more, and especially preferably 245% or more. The upper limit of the elongation at break may be, for example, 500%. If the breaking elongation of the stretched film constituting the first retardation layer is in this range, cracks can be better suppressed under a harsh high-temperature, high-humidity environment due to a synergistic effect with the effect of the shrinkage rate. In addition, in this specification, 'elongation at break' refers to the elongation rate when the film breaks during fixed-end uniaxial stretching at a predetermined stretching temperature (eg, Tg-2°C).

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 1.0 × 10 ^-12 (m ² /N) to 15 × 10 ^-12. (m ² /N), more preferably 2.0 × 10 ^-12 (m ² /N) to 12 × 10 ^-12 (m ² /N). If the absolute value of the photoelastic coefficient is in this range, display unevenness can be suppressed when a polarizing plate with a retardation layer is applied to an image display device.

D-2. Constituent materials of the first phase contrast layer

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

In one embodiment, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, It contains structural units derived from at least one dihydroxy compound selected from the group consisting of di, tri or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol and/ or contains structural units derived from di, tri or polyethylene glycol; More preferably, it contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol. The polycarbonate-based resin may, if necessary, contain structural units derived from other dihydroxy compounds. In addition, details of the polycarbonate-based resin that can be suitably used in the present invention are, for example, Japanese Patent Application Laid-Open No. 2014-10291, Japanese Patent Application Publication No. 2014-26266, Japanese Patent Application Publication No. 2015-212816, It is described in Japanese Patent Application Laid-Open No. 2015-212817 and Japanese Patent Application Publication No. 2015-212818, and the description is incorporated herein by reference.

In one embodiment, the polycarbonate-based resin contains at least one structural unit selected from the group consisting of a structural unit represented by the general formula (1) and/or a structural unit represented by the general formula (2). These structural units are structural units derived from divalent oligofluorene, and may hereinafter be referred to as oligofluorene structural units. Such polycarbonate-based resin has positive refractive index anisotropy.

In one embodiment, the first phase difference layer may further contain an acrylic resin. The content of acrylic resin is typically 0.5 mass% to 1.5 mass%. Additionally, in this specification, the percentage or part of the 'mass' unit is the same as the percentage or part of the 'weight' unit.

In one embodiment, the first phase difference layer may further contain an antioxidant. As an antioxidant, any suitable compound can be used. As a specific example, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: brand name 'Irganox1010' (manufactured by BASF), 1,3 ,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene: Product name 'Irganox1330' (manufactured by BASF), tris(3,5-di-tert) -Butyl-4-hydroxybenzyl)isocyanurate: Product name 'Irganox3114' (manufactured by BASF), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearyl propionate: Product name 'Irganox1076' '(manufactured by BASF), 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: Product name 'Irganox1035' (manufactured by BASF) , N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]: Product name 'Irganox1098' (manufactured by BASF), bis[3-(3- tert-butyl-4-hydroxy-5-methylphenyl)propionic acid] [ethylenebis(oxyethylene)]: brand name 'Irganox245' (manufactured by BASF), 1,6-hexanediolbis[3-(3,5-di) -tert-butyl-4-hydroxyphenyl)propionate] Product name 'Irganox259' (manufactured by BASF), 4-[[4,6-bis(octylthio)-1,3,5-triazine-2- Il]amino]-2,6-di-tert-butylphenol: Product name 'Irganox565' (manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4- (1,1,3,3,-tetramethylbutyl)phenol: Product name 'Adekastave LA-31' (manufactured by ADEKA), etc. The content of antioxidant is typically 1.5 mass% to 3.5 mass%.

D-2-1. Polycarbonate-based resin

<Oligofluorene structural unit>

The oligofluorene structural unit is represented by the above general formula (1) or (2). In general formulas (1) and (2), R ¹ to R ³ are each independently a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R ⁴ to R ⁹ are each independently hydrogen. Atom, substituted or unsubstituted alkyl group with 1 to 10 carbon atoms, substituted or unsubstituted aryl group with 4 to 10 carbon atoms, substituted or unsubstituted acyl group with 1 to 10 carbon atoms, substituted or unsubstituted alkoxy group with 1 to 10 carbon atoms, substituted or an 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, or a substituent. It has a silicon atom, a halogen atom, a nitro group, or a cyano group. However, R ⁴ to R ⁹ may be the same or different from each other, and at least two neighboring groups among R ⁴ to R ⁹ may be bonded to each other to form a ring.

The content of the oligofluorene structural unit in the polycarbonate-based resin is preferably 1% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 15% by mass, relative to the entire resin. It is from 18 mass% to 30 mass%, and is particularly preferably from 18 mass% to 25 mass%. If the content of the oligofluorene structural unit is too high, problems such as excessively large photoelastic coefficient, insufficient reliability, or insufficient retardation generation may occur. Additionally, because the proportion of the oligofluorene structural unit in the resin increases, the range of molecular design narrows, making modification difficult in some cases when modification of the resin is required. On the other hand, even if the desired inverse dispersion wavelength dependence is obtained with a very small amount of oligofluorene structural units, in this case, the optical properties change sensitively depending on slight deviations in the content of oligofluorene structural units. , there are cases where it becomes difficult to manufacture so that various characteristics fall within a certain range.

Details of the oligofluorene structural unit are described, for example, in the pamphlet of International Publication No. 2015/159928. The publication is incorporated herein by reference.

<Other structural units>

Polycarbonate-based resins may typically contain other structural units in addition to oligofluorene structural units. In one embodiment, the other structural units may preferably be derived from dihydroxy compounds or diester compounds. In order to develop the desired inverse dispersion wavelength property, it is necessary to introduce a structural unit with a positive intrinsic birefringence into the polymer structure along with an oligofluorene structural unit with a negative intrinsic birefringence. As other monomers, dihydroxy compounds or diester compounds that serve as raw materials for structural units with positive birefringence are more preferable.

Examples of the copolymerizable monomer include compounds capable of introducing a structural unit containing an aromatic ring, and compounds that do not introduce a structural unit containing an aromatic ring, that is, have an aliphatic structure.

Specific examples of compounds composed of the above aliphatic structure are given below. Ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1 , dihydroxy compounds of straight-chain aliphatic hydrocarbons such as 9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; Dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol Dihydroxy compounds that are secondary alcohols and tertiary alcohols of alicyclic hydrocarbons, such as those exemplified by the like; 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2,6-decalindimethanol, 1, Dihydes derived from terpene compounds, such as 5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbonane dimethanol, 2,5-norbonane dimethanol, 1,3-adamantane dimethanol, limonene, etc. Dihydroxy compounds, which are primary alcohols of alicyclic hydrocarbons, such as hydroxy compounds; Oxyalkylene 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, and sebacic acid.

Specific examples of compounds into which a structural unit containing the aromatic ring can be introduced are given below. 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl) Propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4 -Hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1, 1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxy) Phenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl) Decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl) Benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hyde Roxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide , aromatic bisphenol compounds such as bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3, 3'-dichlorodiphenyl ether; 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxy dihydroxy compounds having an ether group bonded to an aromatic group such as ethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, and bis(4-(2-hydroxyethoxy)phenyl)sulfone; Terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, Aromatic dicarboxylic acids such as 4,4'-diphenylsulfonedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

In addition, the aliphatic dicarboxylic acid and aromatic dicarboxylic acid components mentioned above can be used as dicarboxylic acid itself as a raw material for the polyester carbonate, but depending on the manufacturing method, dicarboxylic acid esters such as methyl ester, phenyl ester, or dicarboxylic acid halide. Dicarboxylic acid derivatives such as these can also be used as raw materials.

As copolymerized monomers, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and 9,9-bis(4-hyde), which are conventionally known as compounds having a structural unit with negative birefringence. Dihydroxy compounds having a fluorene ring such as oxyphenyl)fluorene and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and dicarboxylic acid compounds having a fluorene ring are also used as oligofluorene compounds. Can be used in combination.

The resin used in the embodiment of the present invention preferably contains a structural unit represented by the following formula (3) as a copolymerization component among the structural units that can be introduced by the compound containing the alicyclic structure.

As a dihydroxy compound into which the structural unit of the formula (3) can be introduced, spiroglycol can be used.

In the resin used in the embodiment of the present invention, it is preferable that the structural unit represented by the above formula (3) is contained in an amount of 5% by mass or more and 90% by mass or less. As for the upper limit, 70 mass% or less is more preferable, and 50 mass% or less is especially preferable. As for the lower limit, 10 mass% or more is more preferable, 20 mass% or more is more preferable, and 25 mass% or more is especially preferable. If the content of the structural unit represented by the above formula (3) is more than the above lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Additionally, compatibility with acrylic resin is improved, and the transparency of the resulting resin composition can be further improved. Additionally, since the polymerization reaction rate of spiroglycol is relatively slow, the polymerization reaction becomes easy to control by suppressing the content below the above upper limit.

The resin used in the embodiment of the present invention preferably contains a structural unit represented by the following formula (4) as a copolymerization component.

Examples of dihydroxy compounds into which the structural unit represented by the formula (4) can be introduced include isosorbide (ISB), isomannide, and isoidide, which are stereoisomers. These may be used individually, or two or more types may be used in combination.

In the resin used in the embodiment of the present invention, it is preferable that the structural unit represented by the above formula (4) is contained in an amount of 5% by mass or more and 90% by mass or less. As for the upper limit, 70 mass% or less is more preferable, and 50 mass% or less is especially preferable. As for the lower limit, 10 mass% or more is more preferable, and 15 mass% or more is especially preferable. If the content of the structural unit represented by the above formula (4) is more than the above lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. In addition, since the structural unit represented by the formula (4) has a high water absorption property, if the content of the structural unit represented by the formula (4) is below the upper limit, the size of the molded article due to water absorption Changes can be suppressed to an acceptable range.

The resin used in the embodiment of the present invention may further contain other structural units. Additionally, these structural units are sometimes referred to as 'other structural units'. As monomers having other structural units, it is more preferable to employ 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, and 1,4-cyclohexanedicarboxylic acid (and derivatives thereof), and 1,4-cyclohexanedicarboxylic acid (and its derivatives) is more preferably used. Hexanedimethanol and tricyclodecanedimethanol are particularly preferred. Resins containing structural units derived from these monomers have excellent balance in optical properties, heat resistance, mechanical properties, etc. Additionally, since the polymerization reactivity of diester compounds is relatively low, from the viewpoint of increasing reaction efficiency, it is preferable not to use diester compounds other than diester compounds containing oligofluorene structural units.

The glass transition temperature (Tg) of the resin used in the embodiment of the present invention is preferably 110°C or higher and 160°C or lower. The upper limit is more preferably 155°C or lower, more preferably 150°C or lower, and particularly preferably 145°C or lower. The lower limit is more preferably 120°C or higher, and particularly preferably 130°C or higher. If the glass transition temperature is outside the above range, heat resistance tends to deteriorate, and dimensional changes may occur after film forming, or quality reliability under the use conditions of the first retardation layer may deteriorate. On the other hand, if the glass transition temperature is excessively high, unevenness in the film thickness may occur during film forming, the film may become brittle, the stretchability may deteriorate, and the transparency of the film may be impaired.

D-2-2. Acrylic resin

As the acrylic resin, an acrylic resin as a thermoplastic resin is used. Monomers that become structural units of acrylic resin include, for example, the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i -Butyl (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, iso Bornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, pentamethylpiperidyl(meth)acrylate, tetramethylpiperidyl(meth)acrylate, dimethylamino Ethyl (meth)acrylate, 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 individually, or two or more types may be used in combination. Forms in which two or more types of monomers are used in combination include copolymerization of two or more types of monomers, blends of two or more homopolymers of one type of monomer, and combinations thereof. Additionally, other monomers (e.g., olefin-based monomers, vinyl-based monomers) that can be copolymerized with these acrylic monomers may be used in combination.

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. As for the lower limit, 80 mass% or more is more preferable, 90 mass% or more is still more preferable, and 95 mass% or more is especially preferable. Within this range, excellent compatibility with the polycarbonate-based resin of the present invention can be obtained. As structural units other than methyl methacrylate, it is preferable to use methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene. Thermal stability can be improved by copolymerizing methyl acrylate. Since the refractive index of the acrylic resin can be adjusted by using phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene, transparency of the resulting resin composition can be improved by matching the refractive index of the resin to be combined. By using such an acrylic resin, a reverse-dispersion retardation film with excellent extensibility and retardation development properties and small haze can be obtained.

The weight average molecular weight Mw of the acrylic resin is 10,000 or more and 200,000 or less. The lower limit is preferably 30,000 or more, and particularly preferably 50,000 or more. The upper limit is preferably 180,000 or less, and particularly preferably 150,000 or less. If the molecular weight is within this range, compatibility with the polycarbonate-based resin is obtained, thereby improving the transparency of the final retardation film (retardation layer), and also achieving the effect of sufficiently improving extensibility during stretching. . However, the above weight average molecular weight is the molecular weight in terms of polystyrene, measured by GPC. Additionally, it is preferable from the viewpoint of compatibility that the acrylic resin does not contain substantially a branched structure. That it does not contain a branched structure can be confirmed by the fact that the GPC curve of the acrylic resin is unimodal.

D-2-3. Blend of polycarbonate-based resin and acrylic-based resin

When polycarbonate-based resin and acrylic resin are used together, the polycarbonate-based resin and acrylic resin are blended and provided as a resin composition to the manufacturing method of the retardation film (first retardation layer) (the manufacturing method is described later in Section D-3) do). Polycarbonate-based resin and acrylic-based resin can be blended, preferably in a molten state. A typical method of blending in a molten state includes melt kneading using an extruder. The kneading temperature (molten resin temperature) is preferably 200°C to 280°C, more preferably 220°C to 270°C, and even more preferably 230°C to 260°C. If the kneading temperature is within this range, pellets of a resin composition in which both resins are uniformly blended can be obtained while suppressing thermal decomposition. If the temperature of the molten resin in the extruder exceeds 280°C, coloring and/or thermal decomposition of the resin may occur. On the other hand, if the temperature of the molten resin in the extruder is lower than 200°C, the resin viscosity may become too high, which may place an excessive load on the extruder or result in insufficient melting of the resin. Additionally, any appropriate configuration may be adopted as the extruder configuration, screw configuration, etc. In order to obtain resin transparency that can withstand optical film applications, it is preferable to use a twin-screw extruder. In addition, the remaining low molecular components in the resin and the low molecular weight thermally decomposed components during extrusion and kneading may contaminate the cooling rolls and conveyance rolls during the film forming process and stretching process. In order to remove these, an extruder equipped with a vacuum vent is used. It is desirable to use

The content of the acrylic resin in the resin composition (as a result, the first phase difference layer) is 0.5% by mass or more and 2.0% by mass or less as described above. As for the lower limit, 0.6 mass% or more is more preferable. The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by weight or less, more preferably 0.9% by weight or less, and especially preferably 0.8% by weight or less. In this way, by mixing acrylic resin with polycarbonate resin in a very limited ratio, extensibility and retardation development can be significantly increased. Additionally, haze can be suppressed. This effect is not theoretically clear, but is an unexpected and excellent effect obtained through trial and error. Additionally, if the content of acrylic resin is too small, the above-mentioned effects may not be obtained. On the other hand, if the content of acrylic resin is too high, the haze may become high. In addition, the extensibility and phase difference generation properties are often insufficient or rather deteriorated compared to those within the above range.

For the purpose of modifying properties such as mechanical properties and/or solvent resistance, the resin composition includes aromatic polycarbonate, aliphatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, Synthetic resins such as AS, polylactic acid, polybutylene succinate, rubber, and combinations thereof may be further blended.

The resin composition may further contain additives. Specific examples of additives include heat stabilizers, antioxidants, catalyst deactivators, ultraviolet absorbers, light stabilizers, mold release agents, dye pigments, impact modifiers, antistatic agents, lubricants, lubricants, plasticizers, compatibilizers, nucleating agents, flame retardants, inorganic fillers, and foaming agents. You can. The type, number, combination, content, etc. of additives contained in the resin composition can be appropriately set depending on the purpose.

D-3. Method of forming first phase contrast layer

The first retardation layer is obtained by forming a film from the polycarbonate-based resin (resin composition when using an acrylic resin together) described in D-2 above, and further stretching the film. As a method of forming the film, any suitable molding processing method can be employed. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, cast coating (eg, casting method), calendar molding, and heat press. Among them, the extrusion molding method or the cast coating method is preferable because it can increase the smoothness of the resulting film and obtain good optical uniformity. Since there is a risk of problems due to residual solvent in the cast coating method, extrusion molding method is particularly preferred, especially melt extrusion molding method using T die, from the viewpoint of productivity of the film and ease of subsequent stretching treatment. Molding conditions can be appropriately set depending on the composition and type of the resin used, the characteristics desired for the first phase difference layer, etc. In this way, a resin film containing polycarbonate-based resin and, if necessary, acrylic-based resin can be obtained.

The thickness of the resin film (unstretched film) can be set to any appropriate value depending on the desired thickness of the obtained first retardation layer, desired optical properties, stretching conditions described later, etc. Preferably it is 50㎛~300㎛.

For the stretching, any appropriate stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) may be employed. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end shrinking, and fixed end shrinking may be used singly or simultaneously or sequentially. Regarding the stretching direction, it can be carried out in various directions or dimensions, such as the longitudinal direction, the width direction, the thickness direction, and the oblique direction.

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

In one embodiment, the stretching temperature of the film is preferably between the glass transition temperature (Tg) of the polycarbonate resin and Tg+30°C, more preferably between Tg and Tg+15°C, and most preferably between Tg and Tg+10°C. When using an acrylic resin together, the stretching temperature is a temperature below Tg. Normally, when stretching a polycarbonate-based resin film, the film is in a glassy state at a temperature below Tg, so stretching is practically impossible. On the other hand, by mixing a small amount of acrylic resin (typically polymethyl methacrylate), stretching below Tg is possible without substantially changing the Tg of the polycarbonate resin. In addition, although it is not clear in theory, by performing stretching below Tg, an inverse dispersion retardation film (first retardation layer) with excellent stretchability and retardation development properties and small haze can be realized. Specifically, the stretching temperature is preferably Tg to Tg-10°C, more preferably Tg to Tg-8°C, and even more preferably Tg to Tg-5°C. In addition, the film can be appropriately stretched even at a temperature higher than Tg, for example, as long as it is about Tg+5°C, or even up to about Tg+2°C, for example.

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

If necessary, the stretched film may be subjected to relaxation treatment. As a result, the stress generated by stretching can be alleviated, and a retardation layer having the desired shrinkage rate can be formed. As the relaxation treatment conditions, any appropriate conditions can be adopted. For example, the stretched film is contracted at a predetermined relaxation temperature and a predetermined relaxation rate (shrinkage rate) along the stretching direction. The relaxation temperature is preferably 60°C to 150°C. The relaxation rate is preferably 3% to 6%. When a relaxation treatment is performed, the relaxation treatment may typically be performed before the heat treatment.

As described above, the retardation film constituting the first retardation layer can be obtained.

E. Second phase contrast layer

The second retardation layer may be a so-called positive C plate whose refractive index characteristics exhibit the relationship of nz>nx=ny, as described above. By using a positive C plate as the second phase contrast layer, reflection in the oblique direction can be prevented satisfactorily, and wide viewing angle of the anti-reflection function becomes possible. In this case, the phase difference 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, further preferably -90 nm to -200 nm, especially preferably is -100nm~-180nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane phase difference Re(550) of the second phase difference layer may be less than 10 nm.

The second retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material. The second retardation layer preferably comprises a film comprising a liquid crystal material fixed in homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642. 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. First layer and second layer (heat-resistant and moisture-resistant layer)

The first layer 31 and the second layer 32 can each have any appropriate configuration as long as the shear fracture strength can be satisfied. In addition, the first layer 31 and the second layer 32 may have the same structure or different structures. As described above, by providing the first layer, or the first layer and the second layer, a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature, high-humidity environment can be realized. Hereinafter, the first layer 31 and the second layer 32 will be collectively described as a heat-resistant and moisture-resistant layer.

The heat-resistant and moisture-resistant layer preferably has substantially optical isotropy. The in-plane retardation Re(550) of the heat-resistant and moisture-resistant layer is preferably 0 nm to 10 nm, more preferably 0 nm to 5 nm, further preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. The phase difference Rth (550) in the thickness direction of the heat-resistant and moisture-resistant layer is preferably -10 nm to +10 nm, more preferably -5 nm to +5 nm, further preferably -3 nm to +3 nm, and especially preferably -2 nm to +10 nm. It is +2nm. If Re(550) and Rth(550) of the heat-resistant and moisture-resistant layer are within this range, adverse effects on display characteristics can be prevented when applied to an image display device.

The higher the light transmittance at 380 nm when the heat-resistant and moisture-resistant layer has a thickness of 3 μm, the more preferable it is. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. If the light transmittance is within this range, desired transparency can be secured. Light transmittance can be measured, for example, by a method according to ASTM-D-1003.

The lower the haze of the heat-resistant and moisture-resistant layer, the more preferable it is. 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. If the haze is 5% or less, a good sense of clearness can be provided to the polarizing plate with a retardation layer. As a result, the display content of the image display device can be clearly viewed.

In one embodiment, the higher the adhesion between the heat-resistant and moisture-resistant layer and the first phase difference layer, the more preferable it is. Specifically, the adhesion indicates a state of preferably 2 points or less, more preferably 1 point or less, and particularly preferably 0 points in the base wood peeling test described in JIS K 5600-5-6. . If the adhesion is 2 points or less according to the base material peeling test, peeling of the polarizer with a retardation layer in a harsh high-temperature, high-humidity environment can be well suppressed, and external appearance problems such as peeling during rework can be suppressed.

As described above, the heat-resistant and moisture-resistant layer is typically a cured layer or solidified layer of a 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, in addition to a simple cured layer, a hard coat layer, an adhesive layer composed of an active energy ray-curable adhesive, and a crosslinking layer using a crosslinking agent. The solidified layer may be, for example, a solidified layer of a coating film of an organic solvent solution of a thermoplastic resin. These may constitute a heat-resistant and moisture-resistant layer individually, or two or more types may be combined to constitute a heat-resistant and moisture-resistant layer.

(hard coat layer)

The hard coat layer (substantially the composition forming the hard coat layer) contains a curing component and typically a photopolymerization initiator. Representative examples of the curing component include active energy ray-curable (meth)acrylate. Examples of active energy ray-curable (meth)acrylate include ultraviolet ray-curable (meth)acrylate and electron beam-curable (meth)acrylate. Preferably it is ultraviolet curable (meth)acrylate. This is because a hard coat layer can be formed efficiently with a simple processing operation. Ultraviolet-curable (meth)acrylate includes ultraviolet-curable monomers, oligomers, polymers, etc. The ultraviolet curable (meth)acrylate contains a monomer component and an oligomer component having preferably 2 or more ultraviolet polymerizable functional groups, more preferably 3 to 6 units. Specific examples of UV-curable (meth)acrylates include urethane acrylate, pentaerythritol triacrylate, ethoxylated glycerin triacrylate, and polyether urethane diacrylate. In addition to these, the curing component of the active energy ray curable adhesive described later may be used. The hardening component may be used individually or two or more types may be used together. The curing method may be a radical polymerization method or a cationic polymerization method. In one embodiment, an organic-inorganic hybrid material obtained by mixing (meth)acrylate with silica particles or a polysilsesquioxane compound may be used. The constituent materials and forming method of the hard coat layer are described in, for example, Japanese Patent Application Laid-Open No. 2011-237789, Japanese Patent Application Laid-Open No. 2020-064236, and Japanese Patent Application Publication No. 2010-152331. The descriptions in these publications are incorporated herein by reference. Additionally, in this specification, ‘(meth)acrylic’ means acrylic and/or methacrylic. Additionally, (meth)acrylic is sometimes simply referred to as acrylic.

(Active energy ray curing adhesive)

Examples of active energy ray-curable adhesives include ultraviolet ray-curable adhesives and electron beam-curable adhesives. Additionally, from the viewpoint of the curing mechanism, examples of active energy ray curable adhesives include radical curing type, cation curing type, anion curing type, and hybrid of radical curing type and cation curing type.

The adhesive, like the composition forming the hard coat layer, contains a curing component and typically a photopolymerization initiator. Typical examples of the curing component include monomers and/or oligomers having functional groups such as (meth)acrylate group and (meth)acrylamide group. Specific examples of curing components include tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic Trimethylolpropane formal acrylate, dioxane glycol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, EO modified diglycerol tetraacrylate, γ-butyrolactone acrylate, polyethylene glycol diacrylate, hydrocephalus Roxypivalic acid neopentyl glycol acrylic acid adduct, acryloyl morpholine, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, N-methylpyrrolidone, diethylacrylamide, hydroxyethyl acrylamide, N- Methylol acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate, neopentyl glycol glycidyl ether , dicyclopentadiene type epoxy resin. As a curing ingredient, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 4-hydroxybutylacrylate, neopentyl glycol diacrylate, isocyanuric acid EO-modified triacrylate, etc. can be used. do. In addition to these, the hardening components of the hard coat layer described above may be used. The hardening component may be used individually or two or more types may be used together. The adhesive may further contain an oligomer component in addition to the curing component described above. By using an oligomer component, the viscosity of the adhesive before curing can be reduced and operability can be improved. Representative examples of oligomer components include (meth)acrylic oligomers and polyurethane-based (meth)acrylic oligomers.

(Cross-linked layer by cross-linking agent)

The cross-linked layer (substantially the composition that forms the cross-linked layer) contains a curing component and a cross-linking agent. Examples of the curing component include those described above regarding the hard coat layer and the active energy ray curable adhesive. The crosslinking agent may be a thermal crosslinking agent or a photo crosslinking agent. That is, the crosslinking layer may be a thermal crosslinking layer or an optical crosslinking layer. Examples of thermal crosslinking agents include organic crosslinking agents and multifunctional metal chelates. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. A polyfunctional metal chelate is one in which a multivalent metal is covalently bonded or coordinated with an organic compound. Examples of photo-crosslinking agents include photoacid generators. Examples of photo acid generators include organic peroxides. The thermal crosslinking agent or the photo crosslinking agent may be used individually, or two or more types may be used in combination.

(Cured layer of thermosetting resin)

As the thermosetting resin, any appropriate thermosetting resin can be used as long as the cured layer has the desired storage modulus. Representative examples of thermosetting resins include epoxy resins, (meth)acrylic resins, unsaturated polyester resins, polyurethane resins, alkyd resins, melamine resins, urea resins, and phenol resins. For example, an oxetane compound (monomer, oligomer, polymer) may be blended with the thermosetting resin.

(frozen layer)

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

The (meth)acrylic resin has a glass transition temperature (Tg) of preferably 100°C to 220°C, more preferably 110°C to 200°C, and still more preferably 120°C to 160°C. The (meth)acrylic resin may have a repeating unit containing a ring structure. Examples of repeating units containing a ring structure include lactone ring units, glutaric acid anhydride units, glutarimide units, maleic anhydride units, and maleimide (N-substituted maleimide) units. Only one type of repeating unit containing a ring structure may be contained in the repeating unit of the (meth)acrylic resin, or two or more types may be contained. 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 a repeating unit containing the above ring structure.

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 phase difference layer can be 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; Novolak-type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; Polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinyl phenol, naphthol type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin. etc. can be mentioned. Preferably, bisphenol A-type epoxy resin, biphenyl-type epoxy resin, and bisphenol F-type epoxy resin are used. Only one type of epoxy resin may be used, or two or more types may be used in combination.

As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the thermoplastic resin can be used. Specific examples of organic solvents 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 parts by weight to 20 parts by weight based on 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the first phase difference layer can be formed.

The thickness of the heat-resistant and moisture-resistant layer is preferably 500 nm to 5 μm, more preferably 800 nm to 4 μm, and still more preferably 1 μm to 3 μm. Even if the heat-resistant and moisture-resistant layer has such a very thin thickness, it is possible to realize a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature and high-humidity environment. If the thickness of the heat-resistant and moisture-resistant layer is too thin, formation of the heat-resistant and moisture-resistant layer itself may become difficult, and even if it is formed, the effect may be insufficient. Even if the thickness of the heat-resistant and moisture-resistant layer is too thick, curling occurs due to curing shrinkage, making it difficult to form the heat-resistant and moisture-resistant layer itself, or the problem is that the heat-resistant and moisture-resistant layer conversely functions as a weak layer without sufficient curing. There are cases where it happens.

The heat-resistant and moisture-resistant layer is typically formed by applying a composition that forms a heat-resistant and moisture-resistant layer to the first phase difference layer and curing or solidifying the coating film. Specifically, the first layer is formed by applying the composition forming the layer to the second main surface of the first retardation layer and curing or solidifying the coating film; The second layer (if present) is formed by applying the composition forming the layer to the first main surface of the first retardation layer and curing or solidifying the coating film. When the heat-resistant and moisture-resistant layer is an active energy ray cured layer, the coating film can be cured by irradiating the coating film with an active energy ray (eg, visible light, ultraviolet ray, or electron beam). When the heat-resistant and moisture-resistant layer is a thermosetting layer, the coating film can be cured by heating the coating film. When the heat-resistant and moisture-resistant layer is a solidified layer, the coating film can be solidified by heating the coating film.

The formation surface on which the heat-resistant and moisture-resistant layer is formed (for example, the surface of the first phase difference layer) may be surface-modified in advance. Specifically, the surface energy of the forming surface may be increased by surface modification. By surface modification, for example, the shear fracture strength of the resulting heat-resistant and moisture-resistant layer can be adjusted. Additionally, the adhesion between the heat-resistant and moisture-resistant layer and the first phase difference layer can be improved. Surface modification is performed, for example, by corona treatment or plasma treatment. These may be used individually or in combination.

G. Image display device

The polarizing plate with a retardation layer can be applied to an image display device. Accordingly, embodiments of the present invention also include an image display device using such a polarizing plate with a retardation layer. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. The image display device according to the embodiment of the present invention typically includes, on its viewer side, the polarizing plate with a retardation layer described in paragraphs A to F above.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, the thickness is a value measured by the following measurement method. Additionally, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

<Thickness>

The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by Nippon Electronics, product name ‘JSM-7100F’). Thickness exceeding 10㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

[Example 1]

(Production of polarizer)

As a thermoplastic resin substrate, an amorphous isophthalic copolymerization polyethylene terephthalate film (thickness: 100 μm), which is long and has a Tg of about 75°C, was used, and corona treatment was performed on one side of the resin substrate.

100 parts by weight of PVA-based resin mixed at 9:1 with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Kosei Chemical Co., Ltd., brand name “Kosefaimer”) was iodinated. 13 parts by weight of potassium was dissolved in water to prepare an aqueous PVA solution (coating solution).

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

The obtained laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (air auxiliary stretching treatment).

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

Next, in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, the final single transmittance (Ts) of the polarizer obtained is the desired value. It was immersed for 60 seconds while adjusting the concentration to achieve this (dyeing treatment).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, while the total stretch ratio was stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed to increase the size by 5.5 times (underwater stretching treatment).

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

Afterwards, it was dried in an oven maintained at about 90°C and brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75°C (dry shrink treatment).

In this way, a polarizer with a thickness of about 5 μm was formed on the resin substrate.

The HC-TAC film was bonded to the surface of the obtained polarizer (the side opposite to the resin substrate) as a visual side protective layer through an ultraviolet curing adhesive. In addition, the HC-TAC film is a film in which a hard coat layer (7 μm thick) was formed on a triacetylcellulose (TAC) film (25 μm thick), and the TAC film was bonded to the polarizer side. Next, the resin substrate was peeled to obtain a polarizing plate having the structure of HC-TAC film/polarizer. The HC-TAC film had a shrinkage rate of 0.03% after being placed in an environment at 85°C for 240 hours.

(Production of retardation film constituting the first retardation layer)

Polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass of spiroglycol (SPG) parts (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10 ^-2 parts by mass (6.78 × 10 ^-5 mol) of calcium acetate monohydrate as a catalyst were introduced. After purging the inside of the reactor with reduced pressure nitrogen, heating was performed using a heat exchanger, and stirring was started when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was started, and 90 minutes after reaching 220°C, the temperature was set to 13.3 kPa. The phenol vapor produced by-product with the polymerization reaction was guided to a reflux condenser at 100°C, the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the phenol vapor that did not condense was guided to a condenser at 45°C for recovery. After nitrogen was introduced into the first reactor and the pressure was restored to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, temperature increase and pressure reduction in the second reactor were started, and in 50 minutes, the internal temperature was 240°C and the pressure was 0.2 kPa. Thereafter, polymerization was allowed to proceed until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor, the pressure was restored, the resulting polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.

After vacuum drying the obtained polyester carbonate resin (pellets) at 80°C for 5 hours, a single screw extruder (manufactured by Toshiba Machinery Co., Ltd., cylinder set temperature: 250°C), T die (width 200 mm, set temperature: 250°C), A long resin film with a thickness of 135 μm was produced using a film forming device equipped with a chill roll (set temperature: 120 to 130°C) and a winder. The obtained long resin film was stretched in the width direction at a stretching temperature of 133°C and a stretching ratio of 2.8 to obtain a retardation film with a thickness of 48 μm. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.82, and Nz coefficient was 1.12.

(Production of liquid crystal alignment solidification layer constituting the second phase difference layer)

20 parts by weight of a side-chain liquid crystal polymer represented by the following formula (I) (the numbers 65 and 35 in the formula represent the mole percent of the monomer unit, and are expressed as a block polymer for convenience: weight average molecular weight 5000), showing a nematic liquid crystal phase 80 parts by weight of polymerizable liquid crystal (manufactured by BASF, product name 'Paliocolor LC242') and 5 parts by weight of a photopolymerization initiator (product name 'Irgacure 907', manufactured by Ciba Specialty Chemicals) and 200 parts by weight of cyclopentanone. was dissolved in to prepare a liquid crystal coating solution. Then, the coating liquid was applied to the PET base material that had been vertically aligned using a bar coater, and then heated and dried at 80°C for 4 minutes to orient the liquid crystal. By irradiating ultraviolet rays to this liquid crystal layer and hardening the liquid crystal layer, a liquid crystal alignment solidification layer (thickness 3 μm) exhibiting a refractive index characteristic of nz>nx=ny was formed on the substrate.

(Preparation of UV curing adhesive 1)

2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name ‘KBM-303’) 5 parts, 4-hydroxybutylacrylate (manufactured by Osaka Yuuki Chemical Co., Ltd.) ) 35 parts, neopentyl glycol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name 'Light Acrylate NP-A'), 24 parts, isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., product name 'Aronics') M-315') 10 parts, pentaerythritol triacrylate (manufactured by Shinnakamura Chemical, product name 'A-TMM-3LM-N') 5 parts, polyurethane-based acrylic oligomer (manufactured by Mitsubishi Chemical Company, product name 'UV3000B') 15 parts, photopolymerization initiator (manufactured by IGM Resins, product name 'Omnirad 184'), 3 parts, photopolymerization initiator (manufactured by San-Apro, product name 'CPI-100P'), 2 parts, and boric acid (Fujifilm Wako) 1 part (manufactured by Junyaku Corporation) was mixed to prepare ultraviolet curing adhesive 1.

(Production of polarizer with phase contrast layer)

The liquid crystal alignment solidification layer was bonded to one side of the retardation film using the UV curing adhesive 1. Specifically, an ultraviolet curing adhesive is applied to the retardation film so that the thickness after curing is 1㎛, cured by irradiating ultraviolet rays under a nitrogen atmosphere so that the accumulated light amount is 900mJ/cm ² , and an adhesive layer is formed on one side of the retardation film. A liquid crystal alignment solidification layer was bonded therebetween.

Next, the polarizing plate was bonded to the other side of the retardation film through an acrylic adhesive layer with a thickness of 5 μm, and a polarizing plate with a retardation layer was obtained.

[Example 2]

When applying the ultraviolet curing adhesive to the retardation film, a polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that corona treatment was performed on the application surface of the retardation film in advance.

[Example 3]

Before bonding the polarizing plate to the retardation film, a polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that a hard coat layer shown below was provided on the retardation film.

(Production of hard coat layer)

13 parts of urethane acrylate (manufactured by Shinnakamura Chemical, product name 'NK Oligo UA-53H'), 17 parts of pentaerythritol triacrylate (manufactured by Osaka Organic Chemicals, product name 'Viscott #300'), ethoxylated glycerin triacrylate 70 parts of acrylate (manufactured by Shinnakamura Chemical, product name 'A-GLY-9E') and 3 parts of photopolymerization initiator (manufactured by IGM Resins, product name 'Omnirad 907') are diluted with a mixed solvent of cyclopentanone/toluene. , a composition for forming a hard coat layer was prepared. This composition for forming a hard coat layer was applied to the retardation film with a wire bar so that the thickness after curing was 2㎛, heated at 60°C for 1 minute, and then irradiated with ultraviolet rays so that the accumulated light amount was 250mJ/cm2 in a nitrogen atmosphere. , a hard coat layer (HC layer) with a thickness of 2 μm was formed.

[Example 4]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 2, except that the HC layer was provided on the retardation film before bonding the polarizing plate to the retardation film.

[Example 5]

The above-mentioned HC layer was provided on the retardation film before bonding the liquid crystal alignment solidification layer to the retardation film, the liquid crystal alignment solidification layer was bonded using the ultraviolet curing adhesive 2 shown below instead of the ultraviolet curing adhesive 1, and the retardation film was bonded to the retardation film. A polarizing plate with a retardation layer was obtained in the same manner as in Example 1, except that the HC layer was provided on the retardation film before bonding the polarizing plate.

(Preparation of UV curing adhesive 2)

53.3 parts of unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (manufactured by Daicel, product name 'Fraxel FA-1DDM'), polyethylene glycol diacrylate (manufactured by Kyoei Chemical Company, product name 'Light Acrylate 9EG') -A') 6.7 parts, acryloylmorpholine 26.7 parts, acrylic polymer (manufactured by Toa Gosei, product name 'ARUFON UP-1190') 13.3 parts, photopolymerization initiator (manufactured by IGM Resins, product name 'Omnirad 907') 3 parts , and 3 parts of a photopolymerization initiator (manufactured by Nippon Kayaku, product name 'KAYACURE-DETX-S') to prepare ultraviolet curing adhesive 2.

[Comparative Example 1]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the liquid crystal alignment solidification layer was bonded using the UV curing adhesive 2 instead of the ultraviolet curing adhesive 1.

[Comparative Example 2]

Before bonding the liquid crystal alignment solidification layer to the retardation film, the above-described HC layer was provided on the retardation film, and the liquid crystal alignment solidification layer was bonded using ultraviolet curing adhesive 2 shown below instead of ultraviolet curing adhesive 1. Examples In the same manner as in 1, a polarizing plate with a retardation layer was obtained.

[Comparative Example 3]

In the same manner as in Example 1, except that the liquid crystal alignment solidification layer was bonded using the UV curing adhesive 2 instead of the UV curing adhesive 1, and the HC layer was provided on the retardation film before bonding the polarizer to the retardation film. , a polarizing plate with a phase contrast layer was obtained.

The following evaluation was performed for each Example and Comparative Example. The evaluation results are summarized in Table 1.

<Evaluation>

1. Shear breaking strength

For each Example and Comparative Example, the shear fracture strength of the layers (first layer, second layer) formed on the surface of the retardation film was measured using an inclined cutting device 'SAICAS EN' manufactured by DAIPLA WINTES Co., Ltd. It was measured using The width of the w cutting edge for inclined cutting used in the measurement was 1 mm, the rake angle was 20°, and the clearance angle was 10°. The measurement was performed at 23°C in constant speed mode (horizontal speed of the cutting edge was 10 μm/sec, vertical speed was 0.1 μm/sec).

From the horizontal force FH acting on the cutting edge in oblique cutting of the layer to be measured, the area D of the shear surface, and the shear angle θ, the shear fracture strength FS (MPa) can be calculated by the following equation. During the oblique cutting process for the layer being measured, the maximum value of FS expressed within the area of 30% to 70% of the depth from the surface on the side where the blade is inserted (the surface on the side opposite to the retardation film) is defined as the shear fracture strength of each layer. It was done.

FS=(FH/2D)cotθ

2. HAST test

The obtained polarizing plate with a retardation layer was subjected to the HAST test, which is an accelerated test for durability in a high-temperature, high-humidity environment. The HAST test was conducted in accordance with JIS C60068. Specifically, the polarizing plate with a retardation layer was placed in an oven controlled at 110°C and 85% RH for 36 hours to heat and humidify, and the state of the polarizing plate with a retardation layer after heating and humidifying was observed with the naked eye and evaluated based on the following criteria. The results are shown in Table 1.

Good: No cracks or peeling was observed.

Acceptable: Minor cracking or delamination noted

Defective: Significant cracks or peeling confirmed

[Table 1]

As is clear from Table 1, cracking and peeling of the polarizing plate with a retardation layer in the examples were suppressed even in a harsh high-temperature, high-humidity environment. In addition, in each Example and Comparative Example, the HAST test was performed omitting the liquid crystal alignment solidification layer, but the results were the same as above regardless of the presence or absence of the liquid crystal alignment solidification layer.

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

10: Polarizer
11: Polarizer
12: protective layer
21: first phase contrast layer
22: second phase contrast layer
31: first layer
32: second layer
100: Polarizer with phase contrast layer

Claims (9)

A first phase difference layer having first and second main surfaces facing each other,
A polarizer disposed on the first main surface side of the first retardation layer,
It includes a first layer disposed on the second main surface side of the first phase difference layer,
The first retardation layer is composed of a stretched resin film and satisfies the relationship Re (450) < Re (550),
The first layer is a resin layer and has a shear fracture strength of 85 MPa or more,
Polarizer with phase contrast layer
(Here, Re(450) and Re(550) are the in-plane retardation measured with light with a wavelength of 450 nm and 550 nm at 23°C, respectively.) A first phase difference layer having first and second main surfaces facing each other,
A polarizer disposed on the first main surface side of the first retardation layer,
A first layer disposed on the second main surface side of the first phase difference layer,
It includes a second layer disposed on the first main surface side of the first phase difference layer,
The first retardation layer is composed of a stretched resin film and satisfies the relationship Re (450) < Re (550),
The first layer is a resin layer and has a shear fracture strength of 60 MPa or more,
The second layer is a resin layer and has a shear fracture strength of 60 MPa or more,
Polarizer with phase contrast layer
(Here, Re(450) and Re(550) are the in-plane retardation measured with light with a wavelength of 450 nm and 550 nm at 23°C, respectively.) According to claim 1 or 2,
Re (550) of the first retardation layer is 100 nm to 200 nm, and the angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40 ° to 50 ° or 130 ° to 140 °. Attached polarizer. According to any one of claims 1 to 3,
A second retardation layer disposed on the second main surface of the first retardation layer and having a refractive index characteristic of nz>nx=ny,
A polarizing plate with a retardation layer, wherein the first layer is disposed between the first retardation layer and the second retardation layer. According to clause 4,
A polarizing plate with a retardation layer, wherein the first layer functions as an adhesive layer. According to any one of claims 1 to 5,
The first phase difference layer is selected from the group consisting of at least one bonding group selected from the group consisting of a carbonate bond and an ester bond, a structural unit represented by the following general formula (1), and a structural unit represented by the following general formula (2) A polarizing plate with a retardation layer comprising at least one structural unit and containing a resin having positive refractive index anisotropy:


In general formulas (1) and (2), R ¹ to R ³ are each independently a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R ⁴ to R ⁹ are each independently hydrogen. Atom, substituted or unsubstituted alkyl group with 1 to 10 carbon atoms, substituted or unsubstituted aryl group with 4 to 10 carbon atoms, substituted or unsubstituted acyl group with 1 to 10 carbon atoms, substituted or unsubstituted alkoxy group with 1 to 10 carbon atoms, substituted or an 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, or a substituent. It has a silicon atom, a halogen atom, a nitro group, or a cyano group; However, R ⁴ to R ⁹ may be the same or different from each other, and at least two neighboring groups among R ⁴ to R ⁹ may be bonded to each other to form a ring. According to any one of claims 1 to 6,
It includes a protective layer disposed on a side opposite to the first retardation layer of the polarizer,
The shrinkage rate after placing the protective layer in an environment of 85°C for 240 hours is less than 0.05%,
Polarizer with phase contrast layer. In clause 7,
A polarizing plate with a retardation layer, wherein the protective layer is composed of a triacetylcellulose film or a cyclic olefin-based resin film. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 8.