KR20240051864A - Optical laminate - Google Patents

Abstract

The present invention provides an optical laminate having excellent optical compensation performance in the stacking direction and the tilt direction.
An optical laminate according to an embodiment of the present invention includes a polarizing member; It is provided with a plurality of phase difference members disposed on the viewing side of the polarizing member, and has an ellipticity measured at each of an elevation angle of 90° and an elevation angle of 30° from an azimuth angle of 0° of 0.8 or more.

Description

Optical laminate {OPTICAL LAMINATE}

The present invention relates to optical laminates.

Image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) are rapidly becoming popular. In image display devices, in order to realize image display and improve image display performance, an optical laminate including a polarizing member and a retardation member is widely used (see, for example, Patent Document 1). However, new uses for image display devices have been developed in recent years. An example of such a use is virtual reality (VR) goggles. VR goggles are being considered for use in various aspects, and there is a demand for high precision. However, even when the optical laminate described in Patent Document 1 is applied to VR goggles, when the image display screen is viewed from an oblique direction, the optical compensation performance is insufficient, and there remains room for improvement in achieving high precision.

Japanese Patent Publication No. 2013-182162

The present invention was made to solve the above conventional problems, and its main purpose is to provide an optical laminate having excellent optical compensation performance in the stacking direction and the tilt direction intersecting the stacking direction.

[1] An optical laminate according to an embodiment of the present invention includes a polarizing member; It is provided with a plurality of retardation members disposed on the viewing side of the polarizing member, and the ellipticity measured at each of the elevation angles of 90° and 30° from the azimuth angle of 0° is 0.80 or more.

[2] In the optical laminate described in [1] above, the ellipticity measured at each of the elevation angles of 90° and 30° at an azimuth angle of 45° may be 0.80 or more.

[3] In the optical laminate according to [1] or [2], the plurality of retardation members include a first retardation member having a refractive index of nz>nx=ny; a second phase difference member functioning as a λ/4 member; a third phase difference member having a refractive index of nz>nx≥ny; The fourth phase difference member having a refractive index of nx>ny≥nz may be included in this order from the viewer's side.

[4] In the optical laminate according to [1] or [2], the plurality of retardation members include a first retardation member having a refractive index of nz>nx=ny; a second phase difference member functioning as a λ/4 member; A fifth phase difference member having a refractive index of nx>nz>ny may be included in this order from the viewer's side.

According to the embodiment of the present invention, an optical laminate having excellent optical compensation performance in the stacking direction and the oblique direction can be realized.

1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention.
FIG. 3 is a schematic plan view for explaining the azimuth angle in the optical laminate of FIG. 1.
FIG. 4 is a schematic side view for explaining the elevation angle in the optical laminate of FIG. 1.

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

(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 phase difference measured with light with a wavelength of λ nm at 23°C. For example, ‘Re(550)’ is the in-plane phase difference measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d, when the thickness of the layer (film) is d (nm).

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

‘Rth(λ)’ is the phase difference in the thickness direction measured with light with a wavelength of λ nm at 23°C. For example, ‘Rth(550)’ is the phase difference in the thickness direction measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d, when the thickness of the layer (film) is d (nm).

(4) Nz coefficient

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

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, ‘45°’ means ±45°.

A. Overall composition of optical laminate

1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention; Figure 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention.

The optical laminate 100 of the illustrated example includes a polarizing member 5 including a polarizing film 51; and a plurality of phase difference members disposed on the viewing side of the polarizing member 5. In the optical laminate 100, the ellipticity measured at an azimuth angle of 0° and an elevation angle of 90° and an elevation angle of 30° is 0.80 or more. The ellipticity measured at an elevation angle of 90° from an azimuth angle of 0° is preferably 0.85 or more, more preferably 0.88 or more, and even more preferably 0.90 or more. The ellipticity measured at an elevation angle of 30° from an azimuth angle of 0° is preferably 0.82 or more, more preferably 0.84 or more, and even more preferably 0.85 or more.

If the ellipticity measured at each of the elevation angles of 90° and 30° at the azimuth angle of 0° is more than the above lower limit, optical compensation performance can be improved in the stacking direction of the optical laminate and the tilt direction intersecting the stacking direction. The upper limit of the ellipticity measured at an azimuth angle of 0° and an elevation angle of 90° and an elevation angle of 30° is typically 1.00 or less, for example, 0.95 or less.

In this specification, ‘azimuth angle’ refers to the reference direction based on the absorption axis direction of the polarizing film, as shown in FIG. 3; It means the angle θ1 formed by the plane direction (direction perpendicular to the stacking direction) of the optical laminate. When the azimuth angle θ1 is 0°, the plane direction and the reference direction are substantially parallel.

In this specification, the “elevation angle” refers to the reference direction based on the surface direction of the optical laminate, as shown in FIG. 4; It is the angle θ2 formed by the measurement direction located on the same virtual plane as the reference direction. The measurement direction is typically a direction that connects the light receiving part of an ellipticity measuring device (typically a Müller matrix polarimeter) and an arbitrary point on the surface of the optical laminate when measuring the ellipticity. When the elevation angle is 0°, the measurement direction and the reference direction are substantially parallel, and when the elevation angle is 90°, the measurement direction and the stacking direction are substantially parallel.

In this specification, ‘ellipticity’ is an index indicating whether light (polarization) is close to circular or linear polarization, and is the ratio (b/a) of the minor axis radius b to the major axis radius a of elliptically polarized light. An ellipticity of 1.0 means substantially circular polarization, and an ellipticity of 0 means substantially linear polarization.

The ellipticity can be calculated, for example, by the following method.

Each light with a wavelength of 450 nm, 550 nm, and 650 nm is incident on the optical laminate from the polarizing member side, and the major axis radius a and minor axis radius b of the emitted light (elliptically polarized light) passing through the plurality of retardation members are set at a predetermined elevation angle. and azimuth, and the average value of minor axis radius b/major axis radius a of different lights of those wavelengths is taken as the ellipticity. In addition, in more detail, the ellipticity can be calculated based on the method described in the Examples described later.

In one embodiment, the optical laminate 100 has an ellipticity measured at each of an elevation angle of 90° and an elevation angle of 30° at an azimuth of 45° of 0.8 or greater. The ellipticity measured at an elevation angle of 90° at an azimuth angle of 45° is preferably 0.85 or more, more preferably 0.88 or more, and even more preferably 0.90 or more. The ellipticity measured at an elevation angle of 30° at an azimuth of 45° is preferably 0.81 or more, more preferably 0.83 or more, and still more preferably 0.84 or more.

If the ellipticity measured at each of the elevation angles of 90° and 30° at an azimuth angle of 45° is more than the above lower limit, optical compensation performance in the stacking direction and tilt direction can be stably improved. The upper limit of the ellipticity measured at an elevation angle of 90° and an elevation angle of 30° at an azimuth angle of 45° is typically 1.00 or less, for example, 0.95 or less.

As shown in FIGS. 1 and 2, the plurality of retardation members typically include a first retardation member 1 having a refractive index of nz>nx=ny; The second phase difference member 2, which functions as a λ/4 member, is included in this order from the viewer side. According to this configuration, optical compensation performance in the stacking direction and tilt direction can be improved more stably.

As shown in Fig. 1, in one embodiment, a plurality of phase difference members include the above-described first phase difference member 1; The second phase difference member 2 described above; a third phase difference member (3) having a refractive index of nz>nx≥ny; The fourth phase difference member 4 having a refractive index of nx>ny≥nz is included in this order from the viewer side.

Additionally, as shown in FIG. 2, the plurality of phase difference members include the above-described first phase difference member 1; The second phase difference member 2 described above; The fifth phase difference member 50 having a refractive index of nx>nz>ny is included in this order from the viewer side. That is, the plurality of phase difference members may include the fifth phase difference member 50 instead of the third phase difference member 3 and the fourth phase difference member 4. In this case, the angle formed by the absorption axis direction of the polarizing film 51 included in the optical member 5 and the slow axis direction of the fifth phase difference member 50 is, for example, less than 90°±1° (i.e., more than 89.0°, less than 91.0°), and preferably 90°±0.5° or less (i.e., 89.5° or more, 90.5° or less).

According to these configurations, optical compensation performance in the stacking direction and tilt direction can be improved more stably.

In addition, although the number of phase difference members in FIG. 1 is four and the number of phase difference members in FIG. 2 is three, the number of phase difference members is not limited to this. The plurality of phase difference members may further include other phase difference members in addition to the above-mentioned phase difference members.

In one embodiment, the optical laminate 100 includes a substrate 6 located on an opposite side of the second retardation member 2 with respect to the first retardation member 1; The base material 6 is further provided with an optical function layer 7 located on the opposite side of the first retardation member 1. By providing an optical layered product with an optical function layer, an optical function according to the optical function layer can be provided to the optical layered product.

In one embodiment, the optical laminate 100 further includes a first surface protection film 8 located on the opposite side of the second retardation member 2 with respect to the first retardation member 1 . In the illustrated example, the first surface protection film 8 is located on the side opposite to the first retardation member 1 with respect to the substrate 6.

Additionally, the optical laminate 100 may be further provided with a second surface protection film 9. The 2nd surface protection film 9 is located on the side opposite to the 1st retardation member 1 with respect to the 1st surface protection film 8, and is temporarily attached to the 1st surface protection film 8.

In one embodiment, the optical laminate 100 further includes an adhesive layer 20 located on the side opposite to the plurality of retardation members (the side opposite to the viewing side) with respect to the polarizing member 5. Accordingly, the optical laminate 100 can be attached to the image display cell using the adhesive layer 20.

Additionally, the optical laminate 100 may further include a release liner 10. The release liner 10 is located on the side opposite to the polarizing member 5 with respect to the adhesive layer 20, and is temporarily attached to the surface of the adhesive layer 20. The release liner 10 is temporarily attached to the adhesive layer 20 until the optical laminate is attached to the image display cell, and is peeled off from the adhesive layer 20 when the optical laminate is attached.

The optical laminate 100 typically has a rectangular shape when viewed from the stacking direction. More specifically, the optical laminate 100 may have a rectangular shape with a long side of about 10 mm to 70 mm and a short side of about 10 mm to 70 mm, a long side of about 20 mm to 40 mm and a short side of about 10 mm to 30 mm, and more specifically, a long side of about 30 mm and a short side of about 20 mm. .

Hereinafter, the components of the optical laminate will be described.

B. Absence of polarization

The polarizing member 5 is typically an absorption-type polarizing member. The polarizing member 5 is provided with a polarizing film 51 . The polarizing member 5 may be additionally provided with a protective layer. The protective layer may be provided on at least one side of the polarizing film, or may be provided on both sides of the polarizing film. In the illustrated example, the polarizing member 5 is provided with a protective layer 52 provided on the surface of the polarizing film 51 opposite to the viewing side. The protective layer 52 is typically bonded to the polarizing film 51 via any suitable adhesive layer 53. As an adhesive that forms the adhesive layer 53, a representative example is an ultraviolet curing adhesive. The thickness of the adhesive layer 53 is, for example, 1.5 μm or more, preferably 2.0 μm or more, for example, 5.0 μm or less, preferably 3.0 μm or less.

B-1. polarizer

The polarizing film 51 may be any suitable absorption-type polarizing film. The polarizing film 51 typically includes a resin film containing a dichroic material. The polarizing film 51 may be produced from a single-layer resin film, or may be produced using a laminate of two or more layers.

When producing a single-layer resin film, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, are mixed with iodine or dichroic dyes. An absorption-type polarizing film can be obtained by performing dyeing treatment with a dichroic substance, stretching treatment, etc. Among them, an absorption-type polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferable.

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, the PVA-based film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc.

The laminate when manufactured using the above two or more layered laminate is a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate formed by applying a resin substrate and the resin substrate. A laminate of a PVA-based resin layer can be mentioned. An absorption-type polarizing film obtained by using a laminate of a resin substrate and a PVA-based resin layer formed by applying to the resin substrate is, for example, applying a PVA-based resin solution to a resin substrate and drying it to form 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 turning the PVA-based resin layer into an absorption-type polarizing film. 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 involves immersing the laminate in an aqueous boric acid solution and stretching it. Additionally, stretching may further include air stretching the laminate at a high temperature (eg, 95°C or higher) before stretching in an aqueous boric acid solution, if necessary. 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 in the case of 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 or stretching process can be prevented, making it possible to achieve high optical properties. do. Additionally, when the PVA-based resin layer is immersed in a liquid, the disruption of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. As a result, the optical properties of the absorption-type polarizing film 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/absorption type polarizing film laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the absorption type polarizing film), or a foil obtained by peeling the resin substrate from the resin substrate/absorption type polarizing film laminate may be used as is. Any suitable protective layer depending on the purpose may be laminated on the back surface or on the surface opposite to the peeling surface. Details of the manufacturing method of such an absorption-type polarizing film are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent Application Publication No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

The thickness of the polarizing film is, for example, 1 μm or more and 20 μm or less, preferably 2 μm or more and 15 μm or less, more preferably 12 μm or less, further preferably 10 μm or less, particularly preferably 8 μm or less, and even more particularly preferably. is 5㎛ or less.

The polarizing film preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The orthogonal transmittance (Tc) of the polarizing film is, for example, 0.5% or less, preferably 0.1% or less, and more preferably 0.05% or less. The single transmittance (Ts) of the polarizing film is, for example, 41.0% to 46.0%, and is preferably 42.0% or more. The polarization degree of the polarizing film is, for example, 97.0% to 99.997%, preferably 99.0% or more, and more preferably 99.9% or more.

B-2. protective layer

The protective layer is formed from any suitable film that can be used as a protective layer for a polarizing film. Specific examples of materials that become the main components of the film include cycloolefin (COP)-based polynorbornene-based, polyester-based such as polyethylene terephthalate (PET)-based, cellulose-based resins such as triacetylcellulose (TAC), and polycarbonate. Transparent resins such as (PC)-based, (meth)acrylic-based, polyvinyl alcohol-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polyolefin-based, and acetate-based resins can be mentioned. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. Additionally, ‘(meth)acrylic resin’ refers to acrylic resin and/or methacrylic resin. In addition, 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 A resin composition containing an alternating copolymer made of N-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 materials of the resin film can be used individually or in combination.

The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm.

Additionally, a hard coat layer 54 may be provided on the surface of the protective layer 52 on the side opposite to the polarizing film 51 (the side opposite to the viewing side). That is, the optical member 5 may include the hard coat layer 54. The hard coat layer 54 is formed directly on the surface of the protective layer 52. In this specification, ‘directly’ means that no adhesive layer (adhesive layer or adhesive layer) is interposed.

The hard coat layer 54 preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. Hard coat layer 54 may be formed from any suitable resin. The hard coat layer 54 is typically formed from an ultraviolet curable resin. Examples of ultraviolet curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based resins. The thickness of the hard coat layer 54 is, for example, 0.5 μm or more, preferably 1 μm or more, for example, 20 μm or less, and preferably 15 μm or less.

C. Absence of first phase difference

The first retardation member 1 is located on the opposite side to the polarizing member 5 with respect to the second retardation member 2. The first retardation member 1 is typically a retardation film. The first phase difference member 1 is typically attached to the second phase difference member 2 via an arbitrary appropriate adhesive layer 11. As an adhesive that forms the adhesive layer 11, a typical example is an ultraviolet curing adhesive. The thickness of the adhesive layer 11 is, for example, 1.5 μm or more, preferably 2.0 μm or more, for example, 5.0 μm or less, preferably 3.0 μm or less.

The first phase difference member 1 has a refractive index of nz>nx=ny as described above. The layer (film) having a refractive index of nz>nx=ny is sometimes called a “positive C plate” or the like. Additionally, ‘nx=ny’ includes not only cases where nx and ny are completely identical, but also cases where nx and ny are substantially identical. The in-plane phase difference Re(550) of the first phase difference member 1 may be, for example, 0 nm or more and less than 10 nm.

The phase difference Rth (550) in the thickness direction of the first phase difference member 1 is typically less than 0 nm, preferably less than -5 nm, more preferably less than -50 nm, for example, -200 nm or more, preferably -150 nm. or more, more preferably -110 nm or more.

The first retardation member 1 may be formed of any suitable material. The first retardation member 1 is preferably made of a film containing 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 optical compensation layer include the liquid crystal compound and the method for forming the optical compensation layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642. In this case, the thickness of the first phase difference member 1 is, for example, 10 μm or less, preferably 8 μm or less, more preferably 5 μm or less, and typically 0.5 μm or more.

D. Absence of second phase difference

The second phase difference member 2 is located between the first phase difference member 1 and the third phase difference member 3 in FIG. 1, and is positioned between the first phase difference member 1 and the fifth phase difference member 50 in FIG. 2. It is located in between. The second retardation member 2 is typically a retardation film. The second retardation member 2 is typically attached to the third retardation member 3 or the fifth retardation member 50 via any appropriate adhesive layer 21. Examples of the adhesive forming the adhesive layer 21 include (meth)acrylic adhesives, urethane adhesives, silicone adhesives, and rubber adhesives, and preferably (meth)acrylic adhesives. The thickness of the adhesive layer 21 is, for example, 3.5 μm or more and 35 μm or less.

The second phase difference member 2 functions as a λ/4 member as described above. The second phase difference member 2 typically has a refractive index 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.

The in-plane retardation Re(550) of the second phase difference member 2 is typically 100 nm or more and 200 nm or less, preferably 110 nm or more and 180 nm or less, and more preferably 130 nm or more and 150 nm or less. The Nz coefficient of the second phase difference member 2 is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and still more preferably 0.9 to 1.2.

The angle formed by the absorption axis direction of the polarizing film 51 and the slow axis direction of the second retardation member 2 is typically 40° or more and 50° or less, preferably 42° or more and 48° or less, more preferably It is 44° or more and 46° or less, especially preferably 45°.

The second phase difference member 2 may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light, or may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases depending on the wavelength of the measurement light, The phase difference value may exhibit flat wavelength dispersion characteristics that hardly change depending on the wavelength of the measurement light. The second phase difference member 2 preferably exhibits inverse dispersion wavelength characteristics. That is, the second phase difference member 2 preferably satisfies the relationship Re(450)<Re(550).

The resin constituting the second phase difference member 2 includes, for example, polycarbonate-based resin, polyestercarbonate-based resin, polyester-based resin, polyvinyl acetal-based resin, polyarylate-based resin, cyclic olefin-based resin, cellulose-based resin, Examples include polyvinyl alcohol-based resin, polyamide-based resin, polyimide-based resin, polyether-based resin, polystyrene-based resin, and (meth)acrylic-based resin. These resins can be used individually or in combination. The resin constituting the second phase difference member 2 preferably contains polycarbonate-based resin.

The polycarbonate-based resin preferably contains at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and/or structural units shown by the following 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 resins and the like have 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; R ⁴ to R ⁹ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group with 1 to 10 carbon atoms, a substituted or unsubstituted aryl group with 4 to 10 carbon atoms, a substituted or unsubstituted acyl group with 1 to 10 carbon atoms, or a substituted or an unsubstituted alkoxy group with 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group with 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group with 1 to 10 carbon atoms, or a substituted or unsubstituted vinyl group with 1 to 10 carbon atoms. is an ethynyl group, a sulfur atom with a substituent, a silicon atom with a substituent, 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 adjacent groups among R ⁴ to R ⁹ may be bonded to each other to form a ring.

The content ratio of the oligofluorene structural unit in the polycarbonate-based resin is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 18% by mass or more, such as It is 40 mass% or less, preferably 35 mass% or less, more preferably 30 mass% or less, and even more preferably 25 mass% or less. If the content ratio of the oligofluorene structural unit is more than the above lower limit, the desired inverse dispersion wavelength dependence can be stably expressed in the second phase difference member. If the content ratio of the oligofluorene structural unit is below the above upper limit, phase difference can be stably expressed.

The polycarbonate-based resin more preferably contains, in addition to the oligofluorene structural unit, a structural unit represented by the following structural formula (3) and/or a structural unit represented by the following structural formula (4). If the polycarbonate-based resin contains the structural units shown in the following structural formula (3) and/or the following structural formula (4), the desired inverse dispersion wavelength dependence can be more stably expressed in the second phase difference member 2.

The content ratio of the structural unit represented by the structural formula (3) in the polycarbonate resin is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 25% by mass. or more, for example, 90 mass% or less, preferably 70 mass% or less, more preferably 50 mass% or less.

The content ratio of the structural unit represented by the structural formula (4) in the polycarbonate resin is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, for example, 90% by mass or less, Preferably it is 70 mass% or less, more preferably 50 mass% or less.

The resin constituting the second phase difference member 2 particularly preferably contains (meth)acrylic resin in addition to polycarbonate resin.

(meth)acrylic resin typically contains structural units derived from methyl methacrylate. The content ratio of the structural unit derived from methyl methacrylate in the (meth)acrylic resin is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass. That's it. If the content ratio of the structural unit derived from methyl methacrylate is more than the above lower limit, excellent compatibility with the polycarbonate-based resin can be exhibited. The content rate of structural units derived from methyl methacrylate is typically 100% by mass or less.

The weight average molecular weight (Mw) of the (meth)acrylic resin is, for example, 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and for example, 200,000 or less, preferably 180,000 or less, more preferably 150,000 or less. In addition, the above weight average molecular weight is the molecular weight in terms of polystyrene measured by GPC. If the weight average molecular weight (Mw) is within this range, excellent compatibility with polycarbonate-based resin can be stably achieved.

The content ratio of (meth)acrylic resin in the resin constituting the second phase difference member 2 is, for example, 0 mass% or more, preferably 0.5 mass% or more, more preferably 0.6 mass% or more, for example, 2.0 mass% or more. % or less, preferably 1.5 mass% or less, more preferably 1.0 mass% or less, further preferably 0.9 mass% or less, particularly preferably 0.8 mass% or less. If the content ratio of the (meth)acrylic resin is within the above range, extensibility and retardation development can be significantly increased, and haze can be suppressed.

Such a second retardation member 2 is typically a stretched polymer film formed from a resin constituting the second retardation member described above, and is prepared by stretching the polymer film.

The thickness of the second retardation member 2 can be set so that desired optical properties are obtained. The thickness of the second phase difference member 2 is, for example, 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and for example, 60 μm or less, preferably 55 μm or less, more preferably 50 μm. It is as follows.

E. Absence of third phase difference

As shown in FIG. 1, the third phase difference member 3 is located between the second phase difference member 2 and the fourth phase difference member 4. The third retardation member 3 is typically attached to the fourth retardation member 4 via an arbitrary appropriate adhesive layer 31. The adhesive forming the adhesive layer 31 and the thickness range of the adhesive layer 31 are the same as those of the adhesive layer 11 described above.

The third phase difference member 3 has a refractive index of nz>nx≥ny as described above. The third phase difference member 3 preferably has a refractive index of nz>nx>ny. The layer (film) having a refractive index of nz>nx>ny is sometimes called a “positive B plate” or the like.

The in-plane retardation Re(550) of the third retardation member 3 is, for example, 15 nm or more, preferably 20 nm or more, for example, 55 nm or less, preferably 45 nm or less.

The phase difference Rth (550) in the thickness direction of the third phase difference member 1 is typically 0 nm or less, preferably -20 nm or less, more preferably -60 nm or less, for example -250 nm or more, preferably -200 nm. or more, more preferably -150 nm or more.

When the third retardation member 3 has a refractive index of nz>nx>ny, the angle formed by the slow axis direction of the third retardation member 3 and the absorption axis direction of the polarizing film 51 is typically 80° or more. 100° or less, preferably 85° or more and 95° or less, more preferably 88° or more and 92° or less, and even more preferably 89° or more and 91° or less. Additionally, the slow axis direction of the third retardation member 3 and the absorption axis direction of the polarizing film 51 may be substantially parallel. In this case, the angle formed by the slow axis direction of the third retardation member 3 and the absorption axis direction of the polarizing film 51 is typically 0°±5° or less, and preferably 0°±1° or less.

The third phase difference member 3 may exhibit inverse dispersion wavelength characteristics, positive wavelength dispersion characteristics, or flat wavelength dispersion characteristics. The third phase difference member 3 preferably exhibits inverse dispersion wavelength characteristics. That is, the third phase difference member 3 preferably satisfies the relationship of Re(450)<Re(550).

The third phase difference member 3 may have any suitable configuration. Specifically, the phase difference member may be used alone, or may be a laminate of two or more identical or different phase difference members. The third retardation member 3 is preferably a single retardation member (retardation film).

The resin constituting the third phase difference member 3 includes, for example, a thermoplastic resin, preferably a polymer showing negative birefringence or a polymer showing positive birefringence. These resins can be used individually or in combination. The resin constituting the third retardation member 3 more preferably contains a polymer that exhibits negative birefringence. By using a polymer that exhibits negative birefringence, a retardation member having a refractive index ellipsoid of nz>nx>ny and excellent uniformity in the slow axis direction can be easily obtained. Here, “exhibiting negative birefringence” means that when a polymer is oriented by stretching, etc., the refractive index in the stretching direction becomes relatively small. In other words, it means that the refractive index in the direction orthogonal to the stretching direction increases. Examples of polymers that exhibit negative birefringence include polymers in which chemical bonds or functional groups with high polarization anisotropy, such as aromatic rings or carbonyl groups, are introduced into the side chains. Specifically, acrylic resin, styrene-based resin, maleimide-based resin, and fumaric acid ester-based resin can be used, and styrene-based resin and fumaric acid ester-based resin are preferred.

The styrene-based resin constituting the third phase difference member 3 is preferably styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-(meth)acrylate copolymer, and styrene-maleimide copolymer. , vinyl ester-maleimide copolymer, and olefin-maleimide copolymer.

As the fumaric acid ester-based resin constituting the third phase difference member 3, a fumaric acid ester-(meth)acrylate copolymer is preferably used.

These can be used individually or in combination of two or more types.

Furthermore, as the polymer showing the negative birefringence, a polymer having a repeating unit represented by the following general formula (I) is preferably also used. Such a polymer may exhibit a higher negative birefringence and may also be excellent in heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using an N-phenyl substituted maleimide in which a phenyl group having a substituent at least in the ortho position is introduced as the N substituent of the maleimide monomer that is the starting material.

In the general formula (I), R ₁ to R ₅ each independently represent hydrogen, a halogen atom, carboxylic acid, carboxylic acid ester, hydroxyl group, nitro group, or a straight or branched alkyl group or alkoxy group having 1 to 8 carbon atoms ( However, R ₁ and R ₅ are not hydrogen atoms at the same time), R ₆ and R ₇ represent hydrogen or a straight-chain or branched alkyl group or alkoxy group having 1 to 8 carbon atoms, and n represents an integer of 2 or more.

Such a third retardation member 3 is typically a stretched film of a polymer film formed from a resin constituting the above-described third retardation member 3, and is prepared by stretching the polymer film under any appropriate stretching conditions. do.

The thickness of the third retardation member 3 can be set so that desired optical properties are obtained. The thickness of the third phase difference member 3 is, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and for example, 70 μm or less, preferably 60 μm or less, more preferably 40 μm. It is as follows.

F. Fourth phase difference member (4)

The fourth retardation member 4 is typically bonded to the polarizing film 51 via any suitable adhesive layer 41. The adhesive forming the adhesive layer 41 and the thickness range of the adhesive layer 41 are the same as those of the adhesive layer 11 described above. The fourth retardation member 4 is typically a retardation film.

The fourth phase difference member 4 exhibits a refractive index of nx>ny≥nz as described above. The layer (film) having a refractive index of nx>ny>nz is sometimes called a “negative B plate” or the like. A layer (film) having a refractive index of nx>ny=nz may be referred to as a “positive A plate” or the like. Additionally, ‘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. The fourth phase difference member 4 preferably exhibits a refractive index of nx>ny>nz.

The in-plane retardation Re(550) of the fourth retardation member 4 is, for example, 70 nm or more, preferably 90 nm or more, for example, 140 nm or less, preferably 130 nm or less.

The phase difference Rth (550) in the thickness direction of the fourth phase difference member 4 is, for example, 40 nm or more, preferably 60 nm or more, and is, for example, 120 nm or less, preferably 100 nm or less.

The angle formed by the slow axis direction of the fourth retardation member 4 and the absorption axis direction of the polarizing film 51 is typically 80° or more and 100° or less, preferably 85° or more and 95° or less, and more preferably 88°. ° or more and 92° or less, more preferably 89° or more and 91° or less. Additionally, the slow axis direction of the fourth retardation member 4 and the absorption axis direction of the polarizing film 51 may be substantially parallel. In this case, the angle formed by the slow axis direction of the fourth retardation member 4 and the absorption axis direction of the polarizing film 51 is typically 0°±5° or less, and preferably 0°±1° or less.

The slow axis direction of the third phase difference member 3 and the slow axis direction of the fourth phase difference member 4 are preferably substantially parallel. In this case, the angle formed by the slow axis direction of the third phase difference member 3 and the slow axis direction of the fourth phase difference member 4 is typically 0°±5° or less, preferably 0°±1° or less. am.

The fourth phase difference member 4 may exhibit inverse dispersion wavelength characteristics, positive wavelength dispersion characteristics, or flat wavelength dispersion characteristics. The fourth phase difference member 4 preferably exhibits flat wavelength dispersion characteristics.

Examples of the resin constituting the fourth phase difference member 4 include norbornene-based resin, polycarbonate-based resin, cellulose-based resin, polyvinyl alcohol-based resin, and polysulfone-based resin. These resins can be used individually or in combination. The resin constituting the fourth phase difference member 4 preferably contains norbornene-based resin and/or cellulose-based resin.

Such a fourth retardation member 4 is typically a stretched film of a polymer film formed from a resin constituting the above-mentioned fourth retardation member 4, and is prepared by stretching the polymer film under any appropriate stretching conditions. do.

The thickness of the fourth retardation member 4 can be set so that desired optical properties are obtained. The thickness of the fourth phase difference member 4 is, for example, 10 μm or more, preferably 20 μm or more, more preferably 60 μm or more, and for example, 100 μm or less, preferably 90 μm or less, more preferably 80 μm. It is as follows.

G. Absence of fifth phase difference

As shown in FIG. 2 , the fifth retardation member 50 is typically bonded to the polarizing film 51 via any suitable adhesive layer 41 .

The fifth phase difference member 50 has a refractive index of nx>nz>ny as described above. A layer (film) having a refractive index of nx>nz>ny may be referred to as a “Z film” or the like.

The in-plane phase difference Re(550) of the fifth phase difference member 50 is typically 210 nm or more and 360 nm or less, and preferably 250 nm or more and 290 nm or less.

The Nz coefficient of the fifth phase difference member 50 is typically 0.1 or more and 1.0 or less, and preferably 0.3 or more and 0.7 or less.

The fifth phase difference member 50 may exhibit inverse dispersion wavelength characteristics, positive wavelength dispersion characteristics, or flat wavelength dispersion characteristics. The fifth phase difference member 50 preferably exhibits flat wavelength dispersion characteristics.

The fifth retardation member 50 is typically a retardation film made of any suitable resin capable of realizing the above properties. The resin constituting the fifth phase difference member 50 includes, for example, polyarylate-based resin, polyamide-based resin, polyimide-based resin, polyester-based resin, polyaryl ether ketone-based resin, polyamidoimide-based resin, and polyester. Examples include mead-based resin, polyvinyl alcohol-based resin, polyfumaric acid ester-based resin, polyethersulfone-based resin, polysulfone-based resin, cycloolefin-based resin, polycarbonate-based resin, cellulose-based resin and polyurethane-based resin. These resins can be used individually or in combination.

The resin constituting the fifth phase difference member 50 is preferably a cycloolefin-based resin, and more preferably a norbornene-based resin. Specific examples of the norbornene-based resin include “cycloolefin-based resin obtained by hydrogenating a ring-opening polymer of a norbornene-based monomer” described in Japanese Patent Application Laid-Open No. 2006-208925.

The fifth retardation member 50 can be manufactured, for example, by bonding a high-shrinkage film (e.g., polypropylene film) to both sides of a polymer film containing the above-mentioned resin as a main component, and heating and drawing using a longitudinal uniaxial stretching method in a roll stretching machine. You can. The high shrinkage film is used to provide a shrinkage force in a direction perpendicular to the stretching direction during heat stretching and to increase the refractive index (nz) in the thickness direction of the fifth phase difference member 50. There is no particular limitation on the method of bonding the high-shrinkage film to both sides of the polymer film, but a method of bonding the polymer film to the high-shrinkage film includes providing an acrylic adhesive layer with an acrylic polymer as the base polymer and bonding the film. there is.

The thickness of the fifth phase difference member 50 is typically 20 μm or more, preferably 30 μm or more, more preferably 40 μm or more, and typically 200 μm or less, preferably 150 μm or less.

H. Description

The substrate 6 is a functional layer forming substrate for forming the optical functional layer 7, and is located on the side opposite to the second phase difference member 2 (visible side) with respect to the first phase difference member 1. The base material 6 is typically affixed to the first retardation member 1 via any suitable adhesive layer 61. The range of the adhesive forming the adhesive layer 61 and the thickness of the adhesive layer 61 are the same as those of the adhesive layer 21 described above.

The base material 6 is formed of any suitable resin film. Resins constituting the resin film include, for example, polyester resins such as polyethylene terephthalate (PET), cycloolefin resins such as norbornene resins, cycloolefins (e.g. norbornene) and α-olefins (e.g. ethylene). Resins obtained by addition polymerization (COC), cellulose-based resins such as triacetylcellulose (TAC), and (meth)acrylic-based resins can be mentioned. These resins can be used individually or in combination. The resin constituting the base material 6 preferably contains a (meth)acrylic resin, and more preferably contains a (meth)acrylic resin having a glutarimide structure.

The thickness of the base material 6 can be appropriately set depending on the purpose. The thickness of the substrate 6 is, for example, 20 μm or more, preferably 50 μm or more, more preferably 70 μm or more, and for example, 200 μm or less, preferably 150 μm or less, and more preferably 90 μm or less.

I. Optical functional layer

The optical functional layer 7 is typically formed directly on the surface of the substrate 6 opposite to the first retardation member 1 (the surface on the viewing side). Examples of the optical function layer 7 include a hard coat layer, an anti-reflection layer, an anti-sticking layer, and an anti-glare layer. In the illustrated example, the optical function layer 7 is the anti-reflection layer 7a.

The anti-reflection layer 7a is provided to prevent reflection of external light (eg, fluorescent lamps).

As the anti-reflection layer 7a, any suitable structure may be adopted. A typical configuration of the anti-reflection layer 7a includes (1) a single layer of a low refractive index layer with an optical film thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (2) a laminate having a medium refractive index layer, a high refractive index layer, and a low refractive index layer in that order from the base material 6; (3) An alternating multilayer laminate of high refractive index layers and low refractive index layers can be given.

Materials that can form a low refractive index layer include, for example, silicon oxide (SiO ₂ ) and magnesium fluoride (MgF ₂ ). The refractive index of the low refractive index layer is typically around 1.35 to 1.55. Materials that can form a high refractive index layer include, for example, titanium oxide (TIO ₂ ), niobium oxide (Nb ₂ O ₃ or Nb ₂ O ₅ ), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), ZrO ₂ -TiO ₂ may be mentioned. The refractive index of the high refractive index layer is typically about 1.60 to 2.20. As a material capable of forming a medium refractive index layer, for example, titanium oxide (TiO ₂ ), a mixture of a material capable of forming a low refractive index layer and a material capable of forming a high refractive index layer (e.g., titanium oxide and silicon oxide) mixture). The refractive index of the medium refractive index layer is typically about 1.50 to 1.85. The thicknesses of the low refractive index layer, the middle refractive index layer, and the high refractive index layer can be set to realize an appropriate optical film thickness depending on the structural layer of the antireflection layer, the desired antireflection performance, etc.

The thickness of the anti-reflection layer 7a is, for example, about 20 nm to 300 nm.

In the anti-reflection layer 7a, the difference between the maximum reflectance and the minimum reflectance in the wavelength range of 400 nm to 700 nm is preferably 2.0% or less, more preferably 1.9% or less, and even more preferably 1.8% or less. If the difference between the maximum reflectance and the minimum reflectance is within this range, coloring of reflected light can be well prevented.

J. First surface protection film

In the illustrated example, the first surface protection film 8 is located on the side opposite to the first retardation member 1 (visible side) with respect to the substrate 6, and is formed by the adhesive layer 82 to form the optical function layer 7. )(More specifically, it is attached to the anti-reflection layer 7a. The first surface protection film 8 is temporarily attached during the transport process of the optical laminate and peeled off before use of the optical laminate (as a process material) used) may be used, or may be used in a state affixed to the surface of an optical laminate (intended for permanent adhesion).

The first surface protection film 8 includes a film substrate 81; It is provided with an adhesive layer 82 laminated on a film substrate 81.

K. Second surface protection film

The 2nd surface protection film 9 is a process material temporarily attached in the transport process of an optical laminated body and peeled from the 1st surface protection film 8 before the foreign matter inspection of an optical laminated body. The second surface protection film 9 is affixed to the film base 81 of the first surface protection film 8.

L. Adhesive layer

In the illustrated example, the adhesive layer 20 is located on the opposite side of the polarizing film 51 with respect to the protective layer 52, and is laminated on the hard coat layer 54. The adhesive forming the adhesive layer 20 is the same as that of the adhesive layer 21 described above.

The thickness of the adhesive layer 20 is typically 1 μm or more, preferably 5 μm or more, more preferably 12 μm or more, and typically 60 μm or less, preferably 30 μm or less, more preferably It is 23㎛ or less.

M. Release Liner

The release liner 10 is formed of any suitable resin film. Specific examples of materials that serve as the main component of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials of the resin film can be used individually or in combination. The release liner 10 may or may not be transparent.

A release treatment layer may be provided on the adhesive surface of the adhesive layer 20 of the release liner 10. Examples of the release treatment agent that forms the release treatment layer include a silicone-based release treatment agent, a fluorine-based release treatment agent, and a long-chain alkyl acrylate-based release agent. The mold release treatment agent can be used individually or in combination. The thickness of the release treatment layer is typically 50 nm or more and 400 nm or less.

The thickness of the release liner 10 is typically 5 μm or more, preferably 20 μm or more, and typically is 60 μm or less, preferably 45 μm or less. In addition, when a release treatment layer is applied, the thickness of the release liner is a thickness including the thickness of the release treatment layer.

N. Image display device

The optical laminated body described in items A to M above can be applied to an image display device. More specifically, after peeling the second surface protection film 9 from the first surface protection film 8 and peeling the release liner 10 from the adhesive layer 20, the optical laminate is peeled off from the adhesive layer 20. ) and applied to an image display device by attaching it to an image display element (image display cell). Accordingly, one embodiment of the present invention also includes an image display device using such an optical laminate. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical laminated body described in paragraphs A to M above on its viewer side. An image display device includes an image display panel. The image display panel includes image display elements (image display cells). Additionally, an image display device may be referred to as an optical display device, an image display panel may be referred to as an optical display panel, and an image display cell may be referred to as an optical display cell.

In one embodiment, the optical laminate is applied to an image display device such that its lamination direction is substantially parallel to the thickness direction of the image display panel. Thereby, excellent optical compensation performance can be stably provided to the image display device in the frontal direction and in the oblique direction intersecting the frontal direction.

In one embodiment, the optical laminate can be suitably applied to a small display system such as VR goggles. The display system includes an image display element (hereinafter referred to as a display element), a reflector, a first lens unit, a half mirror, and a second lens unit. The components disposed in front of the half mirror (in the illustrated example, the half mirror, the first lens unit, and the second lens unit) may be collectively referred to as the lens unit.

The display element is, for example, a liquid crystal display or an organic EL display, and includes a display surface for displaying an image. The reflection portion is disposed in the front, on the display surface side of the display element. The first lens unit is disposed on the optical path between the display element and the reflection unit. The half mirror is disposed between the display element and the first lens unit. The half mirror is provided integrally with the first lens unit. The second lens unit is disposed on the side opposite to the first lens unit with respect to the reflection unit.

When applying an optical laminate to such a display system, the optical laminate is disposed on an optical path between the display element and the half mirror portion. The lamination direction of the optical laminate is preferably substantially parallel to a direction perpendicular to the display surface of the display element. According to this configuration, excellent optical compensation performance in the frontal direction and oblique direction can be stably provided to a display system such as VR goggles.

The light emitted from the display element passes through the optical laminate, then passes through the half mirror and reaches the reflection portion. The reflector reflects the light toward the half mirror. The half mirror reflects the reflected light from the reflector again toward the reflector. After that, the light passes through the reflection unit and the second lens unit in that order and enters the user's eyes.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement method for each characteristic is as follows.

(1) Measurement of phase difference value

The phase differences of each of the first to fifth phase difference members used in the examples and comparative examples were automatically measured using KOBRA-WPR, manufactured by Oji Instruments. The measurement wavelength was 550 nm and the measurement temperature was 23°C.

(2) Measurement of ellipticity

The ellipticity of the optical laminates obtained in Examples and Comparative Examples was measured using a high-speed, high-precision Müller matrix polarimeter (AxoScan, manufactured by Axometrics). More specifically, the optical laminate is set on the polarimeter, light with a wavelength of 450 nm, 550 nm, and 650 nm is incident from the polarizing member side at 23°C, and light is emitted from the first phase difference member side, and the azimuth angle shown in Table 1 and the minor axis radius b/major axis radius a of the emitted light at the elevation angle were measured, and the average value of minor axis radius b/major axis radius a for the light of the above three types of wavelengths was taken as the ellipticity and is shown in Table 1.

[Production of polarizing member]

<Manufacturing Example 1>

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

Potassium iodide 13 is added to 100 parts by mass of PVA-based resin, which is a mixture of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., brand name 'Kosefaimer') at a ratio of 9:1. The added mass was dissolved in water to prepare a PVA aqueous 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 mass of boric acid with 100 parts by mass 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 mass of water) at a liquid temperature of 30°C, the single transmittance (Ts) of the finally obtained polarizing film is set to a 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 mass of potassium iodide and 5 parts by mass of boric acid with respect to 100 parts by mass 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 mass 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 polarizing film with a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate/polarizing film configuration was obtained.

A cellulose-based resin film (thickness: 32 μm) provided with a hard coat layer as a protective layer was bonded to the surface of the polarizing film (the side opposite to the resin substrate) of the obtained laminate through an ultraviolet curing adhesive layer. Next, the resin substrate was peeled to obtain a polarizing member having a protective layer/polarizing film configuration.

[Production of the first phase difference member (positive C plate) with a refractive index of nz>nx=ny]

<Manufacturing Example 2>

20 parts by mass of a side-chain liquid crystal polymer represented by the following formula (II) (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), represented by a nematic liquid crystalline phase. 80 parts by mass of polymerizable liquid crystal (manufactured by BASF, brand name: Paliocolor LC242) and 5 parts by mass of a photopolymerization initiator (manufactured by Chiba Specialty Chemicals, brand name: Irgacure 907) were dissolved in 200 parts by mass of cyclopentanone to prepare a liquid crystal coating solution. was prepared.

Then, the coating solution was applied to a base film (norbornene-based resin film: manufactured by Zeon Corporation, brand name “Zeonex”) 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 curing the liquid crystal layer, a first phase difference member (first phase difference film) with a thickness of 4 μm was formed on the substrate.

The first phase difference member obtained in this way had a refractive index of nz>nx=ny. The phase difference Rth (550) in the thickness direction of the first phase difference member (positive C plate) is shown in Table 1.

[Production of a second phase difference member functioning as a λ/4 plate]

<Production Example 3>

In 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 parts by mass) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane was added. mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol), and calcium acetate 1 as a catalyst. 1.19×10 ^-2 mass parts (6.78×10 ^-5 mol) of hydrate were added. 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 adjusted 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 liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240°C and the pressure was 0.2 kPa in 50 minutes. After that, polymerization was allowed to proceed until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, 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), Using a film forming device equipped with a chilled roll (set temperature: 120 to 130°C) and a winder, the film is stretched in the width direction of the roll at a stretching temperature of 150°C, and a second retardation member (second phase difference member) with a thickness of 47 μm listed in Table 1 is formed. 2 retardation film) was obtained.

Re(550) of the second phase difference member obtained in this way is 147 nm, and can function as a λ/4 member.

[Production of the third phase difference member (positive B plate) having a refractive index of nz>nx>ny]

<Production Example 4>

48 parts by mass of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical Company, brand name: Metroz 60SH-50), 15601 parts by mass of distilled water, 8161 parts by mass of diisopropyl fumarate, 240 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate, and polymerization. Radical suspension polymerization was performed by adding 45 parts by mass of t-butylperoxypivalate as an initiator, nitrogen bubbling for 1 hour, and then holding the mixture at 49°C for 24 hours while stirring. Next, it was cooled to room temperature, and the suspension containing the resulting polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure.

The obtained fumaric acid ester-based resin was dissolved in a toluene/methyl ethyl ketone mixed solution (toluene/methyl ethyl ketone 50% by mass/50% by mass) to obtain a 20% by mass solution. Furthermore, dope was prepared by adding 5 parts by mass of tributyl trimellitate as a plasticizer to 100 parts by mass of fumaric acid ester resin.

As a support film, a biaxially stretched film (thickness 75 μm, width 1350 mm) of polyester (polyethylene-terephthalate/isophthalate copolymer) was used, and the adjusted dope was formed into a film of arbitrary thickness and heated and dried.

The above-described laminate is set in the feeding section of the stretching device, and while feeding and conveying the laminate to the downstream side, the stretching ratio and stretching temperature are adjusted to achieve the phase difference values shown in Table 1, and free-end uniaxial stretching is carried out in the stretching furnace. was carried out. The support was peeled from the stretched laminate, and a third retardation member (third retardation film) was obtained.

The third retardation member (third retardation film) obtained in this way had a refractive index of nz>nx>ny. The in-plane phase difference Re (550) and the thickness direction phase difference Rth (550) of the third phase difference member are shown in Table 1.

<Production Examples 5 to 9>

A third retardation member (third retardation film) with a thickness of 5 μm shown in Table 1 was obtained in the same manner as in Production Example 4, except that the stretching ratio was changed to obtain the retardation value shown in Table 1.

[Production of the fourth retardation member (negative B plate) with a refractive index of nx>ny>nz]

<Production Example 10>

A long norbornene-based resin film (manufactured by Zeon Corporation, Japan, brand name Zeonor, thickness 40 ㎛, photoelastic coefficient ^3.10 However, by transverse stretching, a fourth retardation member (fourth retardation film) with a thickness of 18 μm was produced.

The fourth phase difference member obtained in this way had a refractive index of nx>ny>nz. Table 1 shows the in-plane phase difference Re (550) and the phase difference Rth (550) in the thickness direction of the fourth phase difference member.

<Production Example 11>

The fourth retardation member shown in Table 1 was obtained in the same manner as in Production Example 10, except that the stretching ratio and drying temperature were changed to obtain the retardation value shown in Table 1.

[Production of the fifth retardation member (Z film) with a refractive index of nx>nz>ny]

<Production Example 12>

On one side of the 130 ㎛ thick norbornene-based resin film (Optes, Zeonoa ZF-14-100), a 60 ㎛ thick shrinkable film (Toray, Torepan BO2873) was applied as an acrylic adhesive layer (20 ㎛ thick). It was joined together through an interposition. Afterwards, it was stretched 1.3 times in an air circulation oven at 146°C to obtain a laminate in which the fifth retardation member (fifth retardation film) was formed on the shrinkable film. Next, the fifth retardation member was peeled from the shrinkable film.

The fifth phase difference member obtained in this way had a refractive index of nx>nz>ny. The in-plane phase difference Re(550) and Nz coefficient of the fifth phase difference member are shown in Table 1.

<<Examples 1 to 7>>

As shown in Table 1, the first phase difference member of Production Example 2, the second phase difference member of Production Example 3, the third phase difference member of any one of Production Examples 4 to 9, and the fourth phase difference member of Production Examples 10 or 11, and the polarizing member (polarizing film/protective layer) of Preparation Example 1 were laminated in this order. Lamination was performed so that the angle formed between the absorption axis direction of the polarizer and the slow axis direction of the retardation members (each of the first to fourth retardation members) was the value shown in Table 1. Additionally, the first phase difference member and the second phase difference member were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm). The second phase difference member and the third phase difference member were bonded together with a (meth)acrylic adhesive layer (thickness: 23 μm). The third phase difference member and the fourth phase difference member were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm). The fourth retardation member and the polarizing member (specifically, the polarizing film) were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm).

In this way, an optical laminate was produced. The obtained optical laminate was subjected to the measurement of ellipticity described above.

<<Example 8>>

As shown in Table 1, the first retardation member of Preparation Example 2, the second retardation member of Preparation Example 3, the fifth retardation member of Preparation Example 12, and the polarizing member (polarizing film/protective layer) of Preparation Example 1. They were stacked in order. Lamination was performed so that the angle formed between the absorption axis direction of the polarizer and the slow axis direction of the retardation members (each of the first retardation member, the second retardation member, and the fifth retardation member) was the value shown in Table 1. Additionally, the first phase difference member and the second phase difference member were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm). The second phase difference member and the fifth phase difference member were bonded together with a (meth)acrylic adhesive layer (thickness: 23 μm). The fifth retardation member and the polarizing member (specifically, the polarizing film) were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm).

In this way, an optical laminate was produced. The obtained optical laminate was subjected to the measurement of ellipticity described above.

<<Example 9>>

As shown in Table 1, the first retardation member of Production Example 2, the second retardation member of Production Example 3, and the polarizing member (polarizing film/protective layer) of Production Example 1 were laminated in this order. Lamination was performed so that the angle formed between the absorption axis direction of the polarizer and the slow axis direction of the retardation member (first retardation member or second retardation member) was the value shown in Table 1. Additionally, the first phase difference member and the second phase difference member were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm). The second retardation member and the polarizing member (specifically, the polarizing film) were bonded together with an ultraviolet curing adhesive layer (1 μm thick).

In this way, an optical laminate was produced. The obtained optical laminate was subjected to the measurement of ellipticity described above.

<<Comparative Example 1>>

As shown in Table 1, the second retardation member of Production Example 3 and the polarizing member (polarizing film/protective layer) of Production Example 1 were laminated in this order. Lamination was performed so that the angle between the absorption axis direction of the polarizer and the slow axis direction of the second retardation member was the value shown in Table 1. Additionally, the second retardation member and the polarizing member (specifically, the polarizing film) were bonded together with an ultraviolet curing adhesive layer (thickness of 1 μm).

In this way, an optical laminate was produced. The obtained optical laminate was subjected to the measurement of ellipticity described above.

<<Comparative Examples 2 to 5>>

An optical laminate was produced in the same manner as in Example 8, except that the angle between the absorption axis direction of the polarizer and the slow axis direction of the fifth retardation member was changed to the value in Table 1. The obtained optical laminate was subjected to the measurement of ellipticity described above.

[Table 1]

The present invention is not limited to the above embodiments, and various modifications are possible. For example, it can be replaced with a configuration that is substantially the same as the configuration shown in the above embodiment, a configuration that exerts the same effect, or a configuration that can achieve the same purpose.

The optical laminate of the present invention is used in image display devices (typically liquid crystal display devices and organic EL display devices), and can be particularly suitably used in very small image display devices (e.g., VR goggles).

100: Optical laminate
1: Absence of first phase difference
2: Absence of second phase difference
3: Absence of third phase difference
4: Fourth phase difference member
5: Absence of polarization
51: polarizing film

Claims (4)

Absence of polarization,
Provided with a plurality of retardation members disposed on a viewing side of the polarizing member,
An optical laminate having an ellipticity of 0.80 or more measured at an elevation angle of 90° and an elevation angle of 30° at an azimuth angle of 0°. According to paragraph 1,
An optical laminate having an ellipticity of 0.80 or more measured at an elevation angle of 90° and an elevation angle of 30° at an azimuth angle of 45°. According to claim 1 or 2,
The plurality of phase difference members are
A first phase difference member having a refractive index of nz>nx=ny,
a second phase difference member functioning as a λ/4 member;
a third phase difference member having a refractive index of nz>nx≥ny;
An optical laminate comprising a fourth phase difference member having a refractive index of nx>ny≥nz in this order from the viewing side. According to claim 1 or 2,
The plurality of phase difference members are,
A first phase difference member having a refractive index of nz>nx=ny,
a second phase difference member functioning as a λ/4 member;
A fifth phase difference member having a refractive index of nx>nz>ny is included in this order from the viewer side,
An optical laminate wherein the angle between the absorption axis direction of the polarizing member and the slow axis direction of the fifth retardation member is less than 90°±1°.