Optically anisotropic laminate, method for producing same, and circularly polarizing plate

Abstract

Provided is an optically anisotropic laminate comprising a first optically anisotropic layer and a second optically anisotropic layer, wherein: the first optically anisotropic layer satisfies formula (1); the second optically anisotropic layer satisfies formulas (2) and (3); the NZ coefficient NZ2 of the second optically anisotropic layer satisfies formula (4); the optically anisotropic laminate satisfies formula (5); and the second optically anisotropic layer contains a resin containing a polymer containing an N-vinylcarbazole monomer unit.　(1): nx1 > ny1 ≥ nz1 (2): nz2 > nx2 > ny2 (3): Re2(550) > 100 nm (4): NZ2 < -0.2 (5): Re(450) < Re(550) < Re(650)

Description

Optically anisotropic laminate, method for manufacturing the same, and circular polarizer

[0001] This invention relates to an optically anisotropic laminate, a method for manufacturing the same, and a circular polarizer.

[0002] Image display devices such as organic electroluminescent image display devices (hereinafter sometimes referred to as "organic EL image display devices") and liquid crystal image display devices may be provided with a phase difference film (Patent Documents 1-2). Furthermore, it is known that vinylcarbazole polymers are used as the material for the optical film (Patent Documents 3-5).

[0003] Japanese Patent Publication No. 7452436, Japanese Unexamined Patent Publication No. 2022-52074, Japanese Patent Publication No. 4347466, Japanese Patent Publication No. 4748806 (Corresponding publication: U.S. Patent Application Publication No. 2005 / 0089676), Japanese Patent Publication No. 4855466 (Corresponding publication: U.S. Patent Application Publication No. 2006 / 0153998)

[0004] One embodiment of providing a phase difference film to an image display device is to provide the phase difference film in combination with a linear polarizer as a circular polarizer for the purpose of reducing ambient light reflection on the display surface of the image display device. In this embodiment, the circular polarizer is required to be able to reduce coloration due to ambient light reflection in both the frontal and inclined directions of the display surface.

[0005] For example, Patent Document 1 describes that an optically anisotropic laminate having a first optically anisotropic layer satisfying predetermined optical properties and a second optically anisotropic layer satisfying predetermined optical properties can reduce the coloration caused by ambient light reflection as described above, as a phase difference film to be combined with a linear polarizer in a circular polarizer. However, there is still room for development and improvement regarding the phase difference film that can reduce ambient light reflection.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a novel optically anisotropic laminate that can realize an image display device in which the color fringing of the display surface when viewed from an inclined direction is reduced; a manufacturing method that can efficiently produce the optically anisotropic laminate with a small number of steps; and a novel circular polarizing plate that can realize an image display device in which the color fringing of the display surface when viewed from an inclined direction is reduced.

[0007] The inventors have found that the above problems can be solved by making the first optical anisotropic layer and the second optical anisotropic layer in an optical anisotropic laminate into layers having specific optical properties, and by using a resin containing a polymer containing N-vinylcarbazole monomer units as the material for the second optical anisotropic layer. The present invention includes the following:

[0008] <1> An optically anisotropic laminate comprising a first optically anisotropic layer and a second optically anisotropic layer, wherein the first optically anisotropic layer satisfies the following formula (1); the second optically anisotropic layer satisfies the following formulas (2) and (3); the NZ coefficient NZ2 of the second optically anisotropic layer satisfies the following formula (4); the optically anisotropic laminate satisfies the following formula (5); and the second optically anisotropic layer comprises a resin containing a polymer containing N-vinylcarbazole monomer units. (1) nx1 > ny1 ≥ nz1 (2) nnz2 > nx2 > ny2 (3) Re2(550) > 100 nm (4) Re(450) < Re(550) < Re(650) (5) where nx1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that gives the maximum refractive index, ny1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that is perpendicular to the direction that gives nx1, and nz1 represents the refractive index in the thickness direction of the first optical anisotropy layer; nx2 represents the refractive index in the in-plane direction of the second optical anisotropy layer in the direction that gives the maximum refractive index, ny2 represents the refractive index in the in-plane direction of the second optical anisotropy layer in the direction perpendicular to the direction that gives nx2, and nz2 represents the refractive index in the thickness direction of the second optical anisotropy layer; Re2(550) represents the in-plane phase difference of the second optical anisotropy layer at a wavelength of 550 nm; Re(450), Re(550), and Re(650) represent the in-plane phase differences of the optical anisotropy laminate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively. <2> The optical anisotropy laminate according to <1>, wherein the first optical anisotropy layer comprises a resin containing a cyclic olefin polymer. <3> The optical anisotropy laminate according to <1> or <2>, wherein the first optical anisotropy layer further satisfies the following formula (6). Re1(550) > 200 nm (6) where Re1(550) represents the in-plane phase difference of the first optical anisotropy layer at a wavelength of 550 nm. <4> The optical anisotropy laminate according to any one of <1> to <3>, wherein the angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer is 85° to 95°.<5> A method for producing an optically anisotropic laminate, comprising in this order: a first step of preparing a resin layer (A) containing a resin containing a cyclic olefin polymer; a second step of forming a resin layer (B) on the resin layer (A) containing a resin containing a polymer containing N-vinylcarbazole monomer units to obtain a multilayer film; and a third step of stretching the multilayer film to obtain an optically anisotropic laminate containing a first optically anisotropic layer which is a stretched layer of resin layer (A) and a second optically anisotropic layer which is a stretched layer of resin layer (B). <6> The method for producing an optically anisotropic laminate according to <5>, wherein the second step comprises applying a resin solution containing a resin containing a polymer containing N-vinylcarbazole monomer units and an organic solvent onto the resin layer (A), and drying the applied resin solution. <7> The method for producing an optically anisotropic laminate according to <5> or <6>, wherein the phase difference Rth in the thickness direction of the resin layer (B) after the second step is -90 nm or less. <8> The method for producing an optically anisotropic laminate according to any one of <5> to <7>, wherein the glass transition temperature TgA of the resin containing the cyclic olefin polymer and the glass transition temperature TgB of the resin containing the polymer containing the N-vinylcarbazole monomer units satisfy the formula: TgB - TgA > 50°C; and the stretching of the multilayer film in the third step is carried out at a temperature of TgA - 5°C or higher and TgA + 10°C or lower. <9> A circular polarizer comprising the optically anisotropic laminate according to any one of <1> to <4> and a linear polarizer.

[0009] According to the present invention, it is possible to provide a novel optically anisotropic laminate that can realize an image display device in which the color fringing of the display surface when viewed from an inclined direction is reduced; a manufacturing method that can efficiently produce the optically anisotropic laminate with a small number of steps; and a novel circular polarizing plate that can realize an image display device in which the color fringing of the display surface when viewed from an inclined direction is reduced.

[0010] Figure 1 is a schematic perspective view showing an optically anisotropic laminate according to one embodiment of the present invention. Figure 2 is a schematic perspective view showing the evaluation model set up when calculating color space coordinates in the simulations for the examples and comparative examples.

[0011] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention. The components of the embodiments shown below can be combined as appropriate. For example, any numerical value selected from the group of numerical values ​​listed as lower limits and any numerical value selected from the group of numerical values ​​listed as upper limits can be combined as appropriate.

[0012] A structural unit formed by polymerizing a monomer is sometimes referred to by adding "monomer unit" after the name of the monomer. For example, a structural unit formed by polymerizing N-vinylcarbazole is also called an N-vinylcarbazole monomer unit. However, the term "monomer unit" is not limited to its formation method. Typically, monomer units are repeating units.

[0013] Furthermore, in the diagrams, identical components are sometimes denoted by the same reference numeral, and their descriptions may be omitted.

[0014] In the following description, a component (e.g., film, layer) is considered "long" if it has a length of five times or more its width, preferably ten times or more, and specifically if it is long enough to be rolled up for storage or transport. There is no particular upper limit to the length; for example, it may be 100,000 times or less its width.

[0015] In the following explanation, unless otherwise specified, the slow axis of a film or layer refers to the slow axis within the plane of the film or layer.

[0016] In the following description, unless otherwise specified, the orientation angle of a film or layer refers to the angle that the lagging axis of the film or layer makes with respect to a reference direction perpendicular to the thickness direction. For long films and layers, unless otherwise specified, the longitudinal direction is used as the reference direction.

[0017] In the following description, unless otherwise specified, the angles formed by the optical axes (slow axis, transmission axis, absorption axis, etc.) of each layer in a component comprising multiple layers represent the angles when the layer is viewed from the thickness direction.

[0018] In the following description, unless otherwise specified, the front direction of a film refers to the direction normal to the main surface of the film, specifically the direction where the polar angle of the main surface is 0° and the azimuth angle is 0°.

[0019] In the following explanation, unless otherwise specified, the inclination direction of a film means a direction that is neither parallel nor perpendicular to the main surface of the film, and specifically refers to a direction in which the polar angle of the main surface is greater than 0° and less than 90°.

[0020] In the following explanation, unless otherwise specified, a material with positive intrinsic birefringence means a material whose refractive index in the stretching direction is greater than its refractive index in the direction perpendicular to it. Similarly, unless otherwise specified, a material with negative intrinsic birefringence means a material whose refractive index in the stretching direction is less than its refractive index in the direction perpendicular to it. The value of intrinsic birefringence can be calculated from the dielectric constant distribution.

[0021] In the following explanation, the term "(meth)acrylic acid" includes "acrylic acid," "methacrylic acid," and combinations thereof.

[0022] In the following explanation, unless otherwise specified, the in-plane phase difference Re of the layer is given by the value Re = (nx - ny) × d. Also, unless otherwise specified, the birefringence Δn of the layer is given by the value Δn = nx - ny, and therefore Δn = Re / d. Also, unless otherwise specified, the phase difference Rth in the thickness direction of the layer is given by the value Rth = [{(nx + ny) / 2} - nz] × d. Furthermore, unless otherwise specified, the NZ coefficient NZ of the layer is given by the value NZ = (nx - nz) / (nx - ny), and can be calculated by NZ = Rth / Re + 0.5. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the layer (in-plane direction) that gives the maximum refractive index. ny represents the refractive index in the aforementioned in-plane direction of the layer that is perpendicular to the direction of nx. nz represents the refractive index in the thickness direction of the layer. d represents the thickness of the layer. Unless otherwise specified, the measurement wavelength is 550 nm.

[0023] In the following description, unless otherwise specified, the directions of elements include errors within a range that does not impair the effects of the present invention, for example, within a range of ±5°, for example, within a range of ±3°, ±2° or ±1°, even if they are "parallel", "perpendicular" and "orthogonal".

[0024] In the following description, unless otherwise specified, the "polarizing plate" includes not only a rigid member but also a flexible member such as a resin film.

[0025] In the following description, unless otherwise specified, the adhesive not only includes a narrow-sense adhesive (an adhesive having a shear storage modulus of 1 MPa to 500 MPa at 23°C after energy ray irradiation or heat treatment), but also includes an adhesive having a shear storage modulus of less than 1 MPa at 23°C. Therefore, the "adhesive layer" includes not only a layer of a narrow-sense adhesive but also a layer of an adhesive.

[0026] <1. Outline of the optically anisotropic laminate> Figure 1 is a perspective view schematically showing an optically anisotropic laminate according to an embodiment of the present invention. As shown in Figure 1, the optically anisotropic laminate 100 includes a first optically anisotropic layer 110 and a second optically anisotropic layer 120.

[0027] Further, the optically anisotropic laminate 100 satisfies the following formulas (1) to (5), and the second optically anisotropic layer 120 includes a resin containing a polymer containing N-vinylcarbazole monomer units. nx1 > ny1 ≥ nz1 (1) nz2 > nx2 > ny2 (2) Re2(550) > 100 nm (3) NZ2 < -0.2 (4) Re(450) < Re(550) < Re(650) (5)

[0028] In the optically anisotropic laminate 100, an example is shown in which the first optically anisotropic layer 110 and the second optically anisotropic layer 120 are in direct contact. That the two layers are "directly" in contact means that there is no other layer between those two layers.

[0029] Further, in the optically anisotropic laminate 100, preferably, the slow axis A １１０ of the first optically anisotropic layer and the slow axis A １２０ of the second optically anisotropic layer form an angle θ １－２ that is orthogonal or substantially orthogonal, specifically, θ１－２ is 85° to 95°.

[0030] The optical anisotropic laminate 100 can preferably be used as a broadband wavelength film in which the first optical anisotropic layer 110 functions as a λ / 2 layer and the second optical anisotropic layer 120 functions as a λ / 4 layer.

[0031] According to the present embodiment, when the optical anisotropic laminate satisfies the formulas (1) to (5) and the second optical anisotropic layer includes a resin containing a polymer containing an N-vinylcarbazole monomer unit, and is combined with a linear polarizer to form a circular polarizing plate, external light reflection can be reduced in a wide wavelength range, and coloration in the inclination direction of the surface provided with the circular polarizing plate (for example, the display surface of an image display device) can be reduced, thereby obtaining an optical anisotropic laminate. Also, usually, such an optical anisotropic laminate can reduce coloration not only in the inclination direction of the surface but also in the front direction.

[0032] Here, in a conventional optical anisotropic laminate, when the optical properties of the first optical anisotropic layer and the second optical anisotropic layer are different from each other, particularly when the NZ coefficient of the second optical anisotropic layer is smaller than 0, after manufacturing each layer separately, those layers are laminated to obtain an optical anisotropic laminate. Therefore, the number of steps increases, and there is a tendency for labor and cost to increase.

[0033] In a conventional manufacturing method, one of the reasons for manufacturing each layer separately is that the stretching conditions required to exhibit the optical properties required for the first optical anisotropic layer and the second optical anisotropic layer are different. Specifically, for the first optical anisotropic layer, for example, by using a resin having a positive intrinsic birefringence, the desired optical properties can be exhibited by stretching in one direction. On the other hand, for the second optical anisotropic layer, for example, by biaxially stretching a resin having a negative intrinsic birefringence value to enhance the biaxiality, the desired optical properties such as an NZ coefficient smaller than 0 can be exhibited. Thus, in a conventional optical anisotropic laminate, since the stretching conditions required to exhibit the required optical properties are different, for example, it has been difficult to obtain a desired optical anisotropic laminate by co-stretching an unstretched multilayer film.

[0034] In contrast, a resin layer containing a polymer containing N-vinylcarbazole monomer units can be formed by general resin layer formation methods such as coating, for example, to create a resin layer in which the phase difference Rth in the thickness direction is a large negative value in absolute terms. Furthermore, by stretching the obtained resin layer in one direction, the Rth can be made to an even larger negative value in absolute terms. The inventors have further discovered that the optical properties required for the second optical anisotropy layer can be expressed by the stretching conditions used to express the optical properties required for the first optical anisotropy layer.

[0035] According to this embodiment, since the optically anisotropic laminate satisfies formulas (1) to (5) above, and the second optically anisotropic layer contains a resin comprising a polymer containing N-vinylcarbazole monomer units, an optically anisotropic laminate capable of reducing the above-mentioned external light reflection can be efficiently manufactured with a small number of steps, for example, using a co-drawing method, thus enabling a highly productive optically anisotropic laminate.

[0036] <2. Optical properties of optically anisotropic laminates> The optically anisotropic laminate according to this embodiment satisfies the above-described formulas (1) to (5).

[0037] In equation (1) (nx1 > ny1 ≥ nz1), nx1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that gives the maximum refractive index, ny1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that is perpendicular to the direction that gives nx1, and nz1 represents the refractive index in the thickness direction of the first optical anisotropy layer.

[0038] Equation (1) shows that the first optical anisotropy layer can function as a so-called positive A plate or a negative B plate.

[0039] In one embodiment, the value of (ny1-nz1) is preferably 0.0010 or less, more preferably 0.0005 or less, and even more preferably 0.0003 or less.

[0040] In equation (2) (nz² > nx² > ny²), nx² represents the refractive index in the in-plane direction of the second optical anisotropy layer that gives the maximum refractive index, ny² represents the refractive index in the in-plane direction of the second optical anisotropy layer that is perpendicular to the direction that gives nx², and nz² represents the refractive index in the thickness direction of the second optical anisotropy layer.

[0041] Equation (2) shows that the second optical anisotropy layer can function as a so-called positive B plate. Equation (2) shows that the second optical anisotropy layer is a layer in which the refractive indices in three directions (nx2, ny2, and nz2) are different, that is, a biaxial layer.

[0042] In equation (3) (Re2(550) > 100 nm), Re2(550) represents the in-plane phase difference of the second optical anisotropy layer at a wavelength of 550 nm. Re2(550) is usually greater than 100 nm, preferably 110 nm or more, more preferably 120 nm or more, even more preferably 130 nm or more, even more preferably 140 nm or more, preferably 200 nm or less, more preferably 190 nm or less, and even more preferably 180 nm or less.

[0043] In equation (4) (NZ2 < -0.2), NZ2 represents the NZ coefficient of the second optical anisotropy layer. NZ2 is a value calculated by (nx2 - nz2) / (nx2 - ny2), and from equation (2), NZ2 is a negative value. NZ2 is usually less than -0.2, preferably -0.25 or less, more preferably -0.27 or less, preferably -0.5 or more, more preferably greater than -0.5, and even more preferably -0.4 or more. By keeping NZ2 within the above range, biaxiality can be enhanced, and at the same time, optical anisotropy laminates can be manufactured efficiently with fewer steps.

[0044] In equation (5) (Re(450) < Re(550) < Re(650)), Re(450), Re(550), and Re(650) represent the in-plane phase differences of the optically anisotropic laminate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

[0045] Equation (5) shows that the in-plane phase difference of the optically anisotropic laminate is inverse wavelength dispersive. By satisfying equation (5), the optically anisotropic laminate can uniformly convert the polarization state of light transmitted through the optically anisotropic laminate over a wide wavelength range. Therefore, by combining such an optically anisotropic laminate with a linear polarizer, the coloration caused by external light reflection on the display surface of an image display device can be effectively reduced over a wide wavelength range.

[0046] In the optically anisotropic laminate according to this embodiment, it is preferable that the NZ coefficient NZ1 of the first optically anisotropic layer is a predetermined value. NZ1 is a value calculated by (nx1 - nz1) / (nx1 - ny1), and from equation (1), NZ1 is a positive value. From the viewpoint of facilitating manufacturing by stretching, NZ1 is preferably 1.0 or more, preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.05 or less.

[0047] The optically anisotropic laminate according to this embodiment preferably satisfies the following formula (6): Re1(550) > 200 nm (6)

[0048] In equation (6) (Re1(550) > 200 nm), Re1(550) represents the in-plane phase difference of the first optical anisotropy layer at a wavelength of 550 nm. Re1(550) is preferably greater than 200 nm, more preferably 240 nm or more, even more preferably 250 nm or more, even more preferably 260 nm or more, preferably 400 nm or less, more preferably 380 nm or less, and even more preferably 360 nm or less. By having the value of Re1(550) within the above range, it is possible to obtain a circular polarizer that can effectively reduce coloration due to reflection of ambient light, and at the same time, an optical anisotropy laminate with an appropriate thickness can be obtained.

[0049] The optically anisotropic laminate according to this embodiment preferably satisfies the following formula (7): Re1(550) > Re2(550) (7)

[0050] In equation (7) (Re1(550) > Re2(550)), Re1(550) and Re2(550) have the same meaning as described above.

[0051] Equation (7) shows that the in-plane phase difference at a wavelength of 550 nm of the first optical anisotropy layer is greater than the in-plane phase difference at a wavelength of 550 nm of the second optical anisotropy layer.

[0052] The value of (Re1(550) - Re2(550)) is usually greater than 0, and preferably a value that allows the optically anisotropic laminate to function as a λ / 4 plate. Specifically, the optically anisotropic laminate preferably satisfies the following formula (8): 100 nm ≤ (Re1(550) - Re2(550)) ≤ 180 nm (8)

[0053] The value of "Re1(550)-Re2(550)" is preferably 100 nm or more, more preferably 110 nm or more, even more preferably 120 nm or more, preferably 180 nm or less, more preferably 160 nm or less, and even more preferably 150 nm or less. When "Re1(550)-Re2(550)" is within the above range, an optically anisotropic laminate can be obtained that can effectively reduce coloration due to reflection of ambient light.

[0054] In this embodiment, the phase difference Rth2(550) in the thickness direction of the second optical anisotropy layer at a wavelength of 550 nm is preferably -170 nm or more, preferably -160 nm or more, more preferably -155 nm or more, preferably -70 nm or less, more preferably -80 nm or less, and even more preferably -90 nm or less.

[0055] In this embodiment, the phase difference Rth1(550) in the thickness direction of the first optical anisotropy layer at a wavelength of 550 nm is preferably adjusted to a range that satisfies the values ​​of NZ1 and Re1(550) described above.

[0056] In this embodiment, it is preferable that the in-plane phase difference of the optically anisotropic laminate is the difference between the in-plane phase difference of the first optically anisotropic layer and the in-plane phase difference of the second optically anisotropic layer, or a value close to that difference. Therefore, for example, it is preferable that the range of the in-plane phase difference Re(550) of the optically anisotropic laminate at a measurement wavelength of 550 nm is the same as the range of "Re1(550) - Re2(550)".

[0057] In this embodiment, the NZ coefficient of the optically anisotropic laminate is preferably 0.20 or higher, more preferably 0.30 or higher, even more preferably 0.40 or higher, preferably less than 1.00, more preferably 0.90 or lower, and even more preferably 0.80 or lower.

[0058] In this embodiment, the angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer is preferably 85° to 95°. In other words, the angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer is preferably a right angle or close to a right angle. The angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer is θ １－２ Therefore, the aforementioned θ １－２ The angle is preferably 85° or more, more preferably 87° or more, even more preferably 88° or more, even more preferably 89° or more, preferably 95° or less, more preferably 93° or less, even more preferably 92° or less, even more preferably 91° or less, and particularly preferably 90°. １－２ Because the range is as described above, when the optically anisotropic laminate according to this embodiment is combined with a linear polarizer, external light reflection in the front and inclined directions of the display surface of the image display device can be effectively reduced, and color distortion can be effectively reduced.

[0059] The phase difference and slow axis direction of the optically anisotropic laminate and its constituent layers according to this embodiment can be measured using a phase difference meter (for example, "AxoScan" manufactured by Axometrics).

[0060] The total light transmittance of the first optical anisotropic layer is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. The total light transmittance of the second optical anisotropic layer is also preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more.

[0061] The haze of the first optical anisotropy layer is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, and ideally 0%. The haze of the second optical anisotropy layer is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, and ideally 0%.

[0062] The total light transmittance of the optically anisotropic laminate is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more.

[0063] The haze of the optically anisotropic laminate is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, and ideally 0%.

[0064] Total light transmittance can be measured using an ultraviolet-visible spectrometer in the wavelength range of 400 nm to 700 nm. Haze can be measured using a haze meter in accordance with JIS K7361-1997.

[0065] <3. Constituent Layers of the Optically Anisotropic Laminate> The optically anisotropic laminate according to this embodiment typically includes at least a first optically anisotropic layer and a second optically anisotropic layer.

[0066] <3.1. First Optical Anisotropic Layer> The first optical anisotropic layer is usually formed from a thermoplastic resin and contains a thermoplastic resin. The first optical anisotropic layer may contain only a thermoplastic resin. Hereinafter, the thermoplastic resin forming the first optical anisotropic layer will also be referred to as resin (1). The thermoplastic resin usually contains a thermoplastic polymer. From the viewpoint of easily manufacturing the optical anisotropic laminate by a manufacturing method including the first to third steps described later, it is preferable that the thermoplastic resin that can be included in the first optical anisotropic layer is a resin with a positive intrinsic birefringence.

[0067] Examples of thermoplastic polymers that may be included in the first optical anisotropy layer include cyclic olefin polymers; polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfides such as polyphenylene sulfide; polyvinyl alcohol; polycarbonate; polyarylate; cellulose esters; polyethersulfone; polysulfone; polyallylsulfone; polyvinyl chloride; rod-shaped liquid crystal polymers; and others. Resins containing these polymers usually have a positive intrinsic birefringence.

[0068] These polymers may be used individually or in combination of two or more types in any ratio.

[0069] Among these polymers, cyclic olefin polymers are preferred. Here, a cyclic olefin polymer means a polymer having structural units obtained by polymerizing cyclic olefins, or a hydride thereof. Cyclic olefins may or may not have substituents.

[0070] When the first optically anisotropic layer contains a resin containing a cyclic olefin polymer, the first optically anisotropic layer and the second optically anisotropic layer containing a resin containing a polymer containing N-vinylcarbazole monomer units can be manufactured particularly smoothly by a manufacturing method including the first to third steps described later. In particular, during the stretching in the third step, fracture and the occurrence of cracks in the second optically anisotropic layer can be effectively reduced, making it possible to easily obtain an optically anisotropic laminate having the desired optical properties.

[0071] Cyclic olefin polymers contain a cyclic structure within their molecule. Typically, cyclic olefin polymers have an alicyclic structure in the repeating units of the polymer. Cyclic olefin polymers can be polymers having an alicyclic structure in the main chain, polymers having an alicyclic structure in the side chains, polymers having an alicyclic structure in both the main chain and side chains, or mixtures of two or more of these in any ratio. From the viewpoint of mechanical strength and heat resistance, cyclic olefin polymers containing an alicyclic structure in the main chain are preferred.

[0072] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures. Among these, cycloalkane and cycloalkene structures are preferred from the viewpoint of mechanical strength and heat resistance, and cycloalkane structures are particularly preferred.

[0073] The range of the number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less per alicyclic structure. When the number of carbon atoms constituting the alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.

[0074] In the cyclic olefin polymer, the proportion of the repeating unit having an alicyclic structure to all the repeating units is preferably 55% by weight or more, more preferably 70% by weight or more, still more preferably 90% by weight or more. When the proportion of the repeating unit having an alicyclic structure to all the repeating units is within this range, the transparency and heat resistance are good.

[0075] Among cyclic olefin polymers, norbornene-based polymers are preferred. Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and hydrogenated products thereof; addition polymers of monomers having a norbornene structure and hydrogenated products thereof. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Among these, hydrogenated products of ring-opening polymers of monomers having a norbornene structure, addition copolymers of monomers having a norbornene structure and α-olefins, and hydrogenated products of addition copolymers of monomers having a norbornene structure and α-olefins are preferred.

[0076] Examples of monomers having a norbornene structure include, for example, bicyclo[2.2.1]hept-2-ene (common name: norbornene), tricyclo[4.3.0.1 ２，５ deca-3,7-diene (common name: dicyclopentadiene), 7,8-benzotricyclo[4.3.0.1 ２，５ deca-3-ene (common name: methanotetrahydrofluorene), tetracyclo[4.4.0.1 ２，５ .1 ７，１０Examples include dodeca-3-ene (common name: tetracyclododecene) and derivatives of these compounds (for example, those having substituents on the ring). Here, examples of substituents include alkyl groups, alkylene groups, polar groups, etc. Multiple substituents may be bonded to the ring, either identical or different in nature. Monomers having a norbornene structure may be used individually or in combination of two or more types.

[0077] Examples of polar groups include heteroatoms or groups of atoms containing heteroatoms. Examples of heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms, and halogen atoms. Specific examples of polar groups include carboxyl groups, carbonyloxycarbonyl groups, epoxy groups, hydroxyl groups, oxy groups, ester groups, silanol groups, silyl groups, amino groups, nitrile groups, and sulfonic acid groups.

[0078] Examples of monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene, and their derivatives; and cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene, and their derivatives. Monomers capable of ring-opening copolymerization with monomers having a norbornene structure may be used individually or in combination of two or more types.

[0079] Ring-opening polymers of monomers having a norbornene structure can be produced, for example, by polymerizing or copolymerizing monomers in the presence of a ring-opening polymerization catalyst.

[0080] In addition copolymers of monomers having a norbornene structure and α-olefins, examples of α-olefins include α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, and 1-butene, and their derivatives. Among these, ethylene is preferred. One type of α-olefin may be used alone, or two or more types may be used in combination.

[0081] Addition polymers of monomers having a norbornene structure can be produced, for example, by polymerizing or copolymerizing monomers in the presence of an addition polymerization catalyst.

[0082] The hydrides of the ring-opening polymers and addition polymers described above can be produced, for example, by hydrogenating the carbon-carbon unsaturated bonds by preferably 90% or more in a solution of the ring-opening polymer and addition polymer in the presence of a hydrogenation catalyst containing a transition metal such as nickel or palladium.

[0083] Examples of norbornene polymer trade names include "ZEONOR" and "ZEONEX" from Nippon Zeon Corporation; "ARTON" from JSR Corporation; and "APPEL" from Mitsui Chemicals, Inc.

[0084] Norbornene polymers may be used individually or in combination of two or more types.

[0085] The weight-average molecular weight Mw of the cyclic olefin polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, preferably 100,000 or less, more preferably 80,000 or less, and particularly preferably 50,000 or less. When the weight-average molecular weight is within this range, the mechanical strength and moldability of the resin containing the cyclic olefin polymer are highly balanced.

[0086] In this specification, the weight-average molecular weight (Mw) may be measured using gel permeation chromatography (GPC). Examples of solvents used in GPC include cyclohexane, toluene, and tetrahydrofuran. When using GPC, the weight-average molecular weight is measured as the relative molecular weight, for example, on a polyisoprene or polystyrene basis.

[0087] The amount of cyclic olefin polymer is preferably 50% to 100% by weight, more preferably 70% to 100% by weight, and even more preferably 90% to 100% by weight, based on 100% by weight of resin (1). When the amount of cyclic olefin polymer is within the above range, resin (1) can be obtained with high heat resistance and transparency.

[0088] The resin (1) may contain any components other than polymers. Examples of optional components that may be included in the resin (1) include colorants such as pigments and dyes; plasticizers; fluorescent whitening agents; dispersants; heat stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; antioxidants; fine particles; surfactants, etc. Any component may be used alone or in combination of two or more types.

[0089] The glass transition temperature Tg of resin (1) is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, preferably 190°C or lower, more preferably 180°C or lower, and even more preferably 170°C or lower. When the glass transition temperature Tg of resin (1) is above the lower limit of the above range, the durability of the first optical anisotropic layer in high-temperature environments can be improved. When it is below the upper limit, the stretching process to obtain the first optical anisotropic layer can be carried out smoothly.

[0090] The glass transition temperatures of resin (1) and the N-vinylcarbazole resin described later can be measured using a differential scanning calorimetry analyzer (for example, "DSC6220" manufactured by S.I.I. Nanotechnology Co., Ltd.) under conditions of a heating rate of 10°C / min, in accordance with JIS K7121.

[0091] The thickness of the first optical anisotropy layer can be set to a thickness that yields the desired optical properties. The thickness of the first optical anisotropy layer is typically 40 μm or more, preferably 50 μm or more, more preferably 60 μm or more, and typically 180 μm or less, preferably 170 μm or less, and more preferably 160 μm or less.

[0092] <3.2. Second Optical Anisotropy Layer> The second optical anisotropy layer contains a resin containing a polymer containing N-vinylcarbazole monomer units. Hereinafter, the polymer containing N-vinylcarbazole monomer units will also be called an N-vinylcarbazole polymer. The resin containing a polymer containing N-vinylcarbazole monomer units will also be called an N-vinylcarbazole resin. The second optical anisotropy layer may contain an N-vinylcarbazole resin, or it may contain only an N-vinylcarbazole resin. N-vinylcarbazole resins are usually thermoplastic resins. N-vinylcarbazole resins also usually have a negative intrinsic birefringence.

[0093] N-vinylcarbazole resins can form resin layers exhibiting a large absolute negative phase difference Rth in the thickness direction by common resin layer formation methods such as coating. Typically, when a resin liquid containing N-vinylcarbazole resin is prepared, and this liquid is coated and dried to form an N-vinylcarbazole resin layer, the resulting resin layer can have a large absolute negative phase difference Rth in the thickness direction. Furthermore, the resulting phase difference Rth in the thickness direction is not lost by stretching the resin layer in one direction. Therefore, after stretching, the value of Rth can be maintained or even made into a larger negative value. This property is unique to N-vinylcarbazole resins. By utilizing this property, it is possible to manufacture optically anisotropic laminates with excellent optical properties represented by equations (1) to (5) in a small number of steps.

[0094] An N-vinylcarbazole monomer unit represents a repeating unit having a structure formed by polymerizing N-vinylcarbazole. While N-vinylcarbazole monomer units are typically formed by polymerization of N-vinylcarbazole, the term also encompasses repeating units formed by other methods.

[0095] The proportion of N-vinylcarbazole monomer units in 100% by weight of the N-vinylcarbazole polymer is preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more. The upper limit is usually 100% by weight or less, and may be 99% by weight or less. When the amount of N-vinylcarbazole monomer units is within the above range, the birefringence of the N-vinylcarbazole resin can be effectively enhanced, and the thickness of the second optical anisotropy layer can be reduced to a degree that satisfies the requirements for proper processing. Typically, the proportion of N-vinylcarbazole monomer units in 100% by weight of the N-vinylcarbazole polymer is the same as the ratio of N-vinylcarbazole to 100% by weight of the total monomers used in the polymerization of the N-vinylcarbazole polymer (charging ratio).

[0096] N-vinylcarbazole polymers may contain any monomer units other than N-vinylcarbazole monomer units. Any monomer unit refers to a monomer unit having a structure formed by polymerizing any monomer other than N-vinylcarbazole. As any monomer, monomer compounds polymerizable with N-vinylcarbazole (e.g., radical polymerizable) can be used, such as (meth)acrylic acid ester monomers like methyl acrylate and methyl methacrylate; diene compound monomers like butadiene and isoprene; and maleimide monomers like N-phenylmaleimide. Any monomer may be used individually or in combination of two or more types.

[0097] The N-vinylcarbazole polymer may be used alone or in combination of two or more types.

[0098] The weight-average molecular weight Mw of the N-vinylcarbazole polymer is preferably 50,000 or more, more preferably 100,000 or more, preferably 500,000 or less, and more preferably 400,000 or less. When the weight-average molecular weight is within this range, the mechanical strength and solubility in the solvent of the N-vinylcarbazole polymer are highly balanced.

[0099] The amount of N-vinylcarbazole polymer is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more, and usually 100% by weight or less, based on 100% by weight of the N-vinylcarbazole resin. When the amount of N-vinylcarbazole polymer is within the above range, the birefringence of the N-vinylcarbazole resin can be effectively enhanced.

[0100] The N-vinylcarbazole resin may contain any components other than the N-vinylcarbazole polymer in combination with the N-vinylcarbazole polymer. Examples of such components include polymers other than the N-vinylcarbazole polymer, and the same examples as the components that resin (1) may contain. One type of component may be used alone, or two or more types may be used in combination.

[0101] The glass transition temperature Tg of the N-vinylcarbazole resin is preferably 150°C or higher, more preferably 160°C or higher, even more preferably 170°C or higher, preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower. The glass transition temperature Tg of the N-vinylcarbazole resin may be higher than the glass transition temperature of resin (1). When the glass transition temperature Tg of the N-vinylcarbazole resin is within the above range, the birefringence of the N-vinylcarbazole resin can be effectively enhanced. In addition, the orientation relaxation of the second optical anisotropy layer can usually be reduced.

[0102] When an optically anisotropic laminate is manufactured by a manufacturing method including the first, second, and third steps described later, it is preferable that the glass transition temperature TgB of the N-vinylcarbazole resin contained in the second optically anisotropic layer is somewhat higher than the glass transition temperature TgA of the resin (1) contained in the first optically anisotropic layer, from the viewpoint of smoothly co-stretching the first optically anisotropic layer and reducing orientation relaxation of the second optically anisotropic layer. Specifically, the difference (TgB - TgA) between the glass transition temperature TgB of the N-vinylcarbazole resin contained in the second optically anisotropic layer and the glass transition temperature TgA of the resin (1) is preferably greater than 50°C, more preferably 55°C or higher, and even more preferably 60°C or higher.

[0103] Furthermore, from the viewpoint of smoothly adjusting the optical properties of the first optical anisotropy layer and the second optical anisotropy layer by co-drawing, it is preferable that the glass transition temperature TgA and the glass transition temperature TgB are not excessively far apart. Specifically, the difference (TgB - TgA) is preferably 90°C or less, more preferably 85°C or less, and even more preferably 75°C or less.

[0104] The birefringence Δn of the second optical anisotropy layer is preferably 0.010 or higher, more preferably 0.015 or higher, and even more preferably 0.020 or higher at a measurement wavelength of 550 nm. The upper limit is preferably 0.060 or lower, and more preferably 0.050 or lower. When the birefringence Δn is within the above range, it becomes easier to appropriately adjust the thickness of the second optical anisotropy layer during manufacturing, effectively improving the surface condition of the second optical anisotropy layer and effectively reducing color unevenness.

[0105] The thickness of the second optical anisotropy layer can be set to a thickness that yields the desired optical properties. The thickness of the second optical anisotropy layer is preferably 20.0 μm or less, more preferably 18.0 μm or less, even more preferably 15.0 μm or less, and may be preferably 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 3.0 μm or more.

[0106] <3.3. Optional Layers> In addition to the first and second optical anisotropic layers described above, the optical anisotropic laminate may include any other layer. Examples of optional layers include an adhesive layer for bonding the optical anisotropic laminate to any optical element, and a thin film provided between the first and second optical anisotropic layers. A specific example of a thin film is an anchor layer for improving the peel strength between the first and second optical anisotropic layers. The thin film preferably has optical isotropy. Specifically, the in-plane phase difference of any thin film is preferably 5 nm or less, more preferably 4 nm or less, even more preferably 3 nm or less, and particularly preferably 2 nm or less at a measurement wavelength of 590 nm, and is usually 0 nm or more, and may be 0 nm.

[0107] When a thin film is provided between the first optical anisotropic layer and the second optical anisotropic layer, the thickness of any thin film is preferably less than 2.0 μm, more preferably less than 1.8 μm, and even more preferably less than 1.5 μm, from the viewpoint of thinning the optical anisotropic laminate. The lower limit of the thin film thickness is preferable as it is thin, and can be, for example, 0.1 μm or more.

[0108] An arbitrary layer may or may not be provided between the first optical anisotropy layer and the second optical anisotropy layer. Preferably, the second optical anisotropy layer is directly attached to the first optical anisotropy layer.

[0109] <4. Method for Manufacturing an Optically Anisotropic Laminate> The optically anisotropic laminate according to this embodiment can be manufactured by any method. The optically anisotropic laminate may be manufactured by manufacturing the first optically anisotropic layer and the second optically anisotropic layer as separate films and laminating these films. However, the optically anisotropic laminate can preferably be manufactured by a method that includes the following first, second, and third steps in this order.

[0110] First step: A step of preparing a resin layer (A). Second step: A step of forming a resin layer (B) containing a polymer containing N-vinylcarbazole monomer units on the resin layer (A) to obtain a multilayer film. Third step: A step of stretching the multilayer film to obtain an optically anisotropic laminate containing a first optically anisotropic layer which is a stretched layer of resin layer (A) and a second optically anisotropic layer which is a stretched layer of resin layer (B).

[0111] The method for manufacturing an optically anisotropic laminate, including the first to third steps, will be described below as the method for manufacturing an optically anisotropic laminate according to this embodiment.

[0112] According to the manufacturing method of this embodiment, the stretching of resin layer (A) and resin layer (B) is performed together in the third step, thus reducing the number of stretching processes. Therefore, the number of processes required for manufacturing the optically anisotropic laminate can be reduced, resulting in more efficient manufacturing.

[0113] Furthermore, in a method where the first optical anisotropic layer and the second optical anisotropic layer are bonded together after their respective manufacturing, a misalignment in the slow phase axis direction may occur due to bonding. On the other hand, in a manufacturing method as in this embodiment, in which a multilayer film is stretched to co-stretch resin layer (A) and resin layer (B) to obtain an optical anisotropic laminate, no misalignment in the slow phase axis direction due to bonding occurs. Therefore, it is easy to precisely control the direction of the slow phase axis of each of the first optical anisotropic layer and the second optical anisotropic layer. Accordingly, the manufacturing method according to this embodiment does not include a bonding step, thus enabling efficient manufacturing of optical anisotropic laminates. The following describes each step.

[0114] <4.1. First Step> The first step is to prepare the resin layer (A). The long resin layer (A) prepared in the first step preferably contains a resin with a positive intrinsic birefringence, and more preferably contains a resin containing a cyclic olefin polymer. The resin layer (A) can be stretched in the third step to become the first optically anisotropic layer. Therefore, when manufacturing an optically anisotropic laminate using the manufacturing method of this embodiment, the resin (1) contained in the first optically anisotropic layer may be the same resin as the resin contained in the resin layer (A).

[0115] Examples of resins with positive intrinsic birefringence that may be included in resin layer (A) include resins containing polymers listed as examples of thermoplastic polymers that may be included in the first optical anisotropy layer. As resins with positive intrinsic birefringence included in resin layer (A), resins containing cyclic olefin polymers are preferred. Examples and preferred examples of cyclic olefin polymers that may be included in resin layer (A) are the same examples as those for cyclic olefin polymers that may be included in resin (1).

[0116] The resin layer (A) is usually a resin film. Such a resin layer (A) can be manufactured by melt molding or solution casting. More specific examples of melt molding include extrusion molding, press molding, inflation molding, injection molding, blow molding, and stretch molding. Among these methods, extrusion molding, inflation molding, and press molding are preferred in order to obtain a resin layer (A) with excellent mechanical strength and surface accuracy, and extrusion molding is particularly preferred from the viewpoint of efficiently and easily manufacturing the resin layer (A). The resin layer (A) is usually manufactured as a long film, but it may also be in the form of a single sheet.

[0117] <4.2. Second Step> The second step is to form a resin layer (B) containing a polymer containing N-vinylcarbazole monomer units on a resin layer (A) to obtain a multilayer film.

[0118] The resin layer (B) formed in the second step is usually long because it is formed on a typically long resin layer (A). In the second step, resin layer (A) can function as a base film for forming resin layer (B).

[0119] The resin layer (B) comprises a resin containing a polymer containing N-vinylcarbazole monomer units, and is typically formed from a resin containing a polymer containing N-vinylcarbazole monomer units.

[0120] The resin layer (B) can be stretched together with the resin layer (A) in the third step to become the second optically anisotropic layer. Therefore, when manufacturing an optically anisotropic laminate using the manufacturing method of this embodiment, the resin containing a polymer containing N-vinylcarbazole monomer units in the second optically anisotropic layer may be the same resin as the resin contained in the resin layer (B). Examples and preferred examples of the resin contained in the resin layer (B) are the same examples as those given for the N-vinylcarbazole-based resin contained in the second optically anisotropic layer.

[0121] Since the orientation angle of the second optical anisotropy layer can be easily controlled to a desired range by stretching in the third step, it is preferable that the in-plane phase difference of the resin layer (B) is 0 nm or close to 0 nm. Specifically, the in-plane phase difference of the resin layer (B) is preferably 10 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, and is usually 0 nm or more, and may be 0 nm.

[0122] The phase difference in the thickness direction of the resin layer (B) may be appropriately determined depending on the type of resin contained in the resin layer (B). In one embodiment, the phase difference in the thickness direction of the resin layer (B) is preferably -90 nm or less, preferably -150 nm or more, more preferably -140 nm or more, and even more preferably -130 nm or more. By including a polymer containing N-vinylcarbazole monomer units in the resin layer (B), the phase difference in the thickness direction can be made a negative value with a large absolute value.

[0123] The thickness of the resin layer (B) may be set appropriately so that the second optical anisotropy layer obtained by stretching the resin layer (B) exhibits a desired phase difference. In one embodiment, the thickness of the resin layer (B) is preferably 20.0 μm or less, more preferably 15.0 μm or less, even more preferably 10.0 μm or less, preferably 3.0 μm or more, more preferably 4.0 μm or more, and even more preferably 4.5 μm or more.

[0124] In the second step, resin layer (B) is formed on resin layer (A). Here, resin layer (B) is formed either directly on resin layer (A) or indirectly via any layer such as a thin film. Here, "directly" means that there is no layer between resin layer (A) and resin layer (B).

[0125] The difference (TgB - TgA) between the glass transition temperature TgB of the resin containing a polymer with N-vinylcarbazole monomer units in resin layer (B) and the glass transition temperature TgA of the resin (preferably a resin containing a cyclic olefin polymer) in resin layer (A) is preferably within the range described above. That is, preferably TgB - TgA > 50°C.

[0126] The formation of the resin layer (B) in the second step preferably includes (2-1) applying a resin solution containing a polymer containing the N-vinylcarbazole monomer units and an organic solvent onto the resin layer (A) to form a layer of resin solution, and (2-2) drying the layer of resin solution. Steps (2-1) and (2-2) are usually carried out in this order.

[0127] The second step, by including steps (2-1) and (2-2), makes it possible to form a resin layer (B) that is thin and has a small in-plane phase difference. Furthermore, the method including steps (2-1) and (2-2) makes it possible to smoothly obtain a resin layer (B) having a phase difference in the thickness direction within the range described above. Typically, a resin layer (B) having a large absolute negative phase difference Rth in the thickness direction can be obtained simply by applying and drying a resin liquid containing an N-vinylcarbazole resin. Therefore, the phase difference Rth in the thickness direction of the resin layer (B) can be made a large absolute negative value before the third step, which is a stretching step.

[0128] Examples of organic solvents used in resin solutions include cyclopentanone, methyl ethyl ketone, and toluene. Furthermore, one type of organic solvent may be used alone, or two or more types may be used in combination.

[0129] Examples of resin liquid application methods include curtain coating, extrusion coating, roll coating, spin coating, dip coating, bar coating, spray coating, slide coating, print coating, gravure coating, die coating, and gap coating.

[0130] After applying the resin liquid onto the resin layer (A), the resin liquid is dried to remove the organic solvent, thereby forming a resin layer (B) on the resin layer (A). Drying can be carried out by methods such as natural drying, heat drying, vacuum drying, or vacuum heat drying.

[0131] <4.3. Third Step> The third step is to obtain an optically anisotropic laminate including a first optically anisotropic layer and a second optically anisotropic layer by stretching the multilayer film. In the third step, the multilayer film comprising resin layer (A) and resin layer (B) obtained in the second step is stretched. By stretching the multilayer film in the third step, the first optically anisotropic layer is obtained from resin layer (A) and the second optically anisotropic layer is obtained from resin layer (B).

[0132] In the third step, the stretching of the multilayer film is preferably carried out in only one direction, at an angle of 0° to 5° with respect to the longitudinal direction of the multilayer film. The stretching direction may also be at an angle of 0° with respect to the longitudinal direction of the multilayer film (i.e., a direction that coincides with the longitudinal direction of the multilayer film).

[0133] In the third step, stretching causes the first optical anisotropic layer obtained from resin layer (A) to exhibit a slow phase axis parallel or nearly parallel to the stretching direction. On the other hand, in the third step, stretching causes the second optical anisotropic layer obtained from resin layer (B) to exhibit a slow phase axis perpendicular or nearly perpendicular to the stretching direction. Therefore, stretching of the multilayer film comprising resin layer (A) and resin layer (B) in the third step causes the angle θ between the slow phase axis direction of the second optical anisotropic layer and the slow phase axis direction of the first optical anisotropic layer to change. １－２ This can typically be set to 85° to 95°.

[0134] The stretching ratio in the third step may be set appropriately according to the optical properties of the prepared resin layer (A), such as the in-plane phase difference, and is preferably 1.10 times or more, more preferably 1.15 times or more, particularly preferably 1.20 times or more, preferably 2.00 times or less, more preferably 1.80 times or less, and particularly preferably 1.60 times or less. When the stretching ratio in the third step is above the lower limit of the above range, the occurrence of wrinkles can be suppressed. Also, when it is below the upper limit, the direction of the slow axis can be easily controlled.

[0135] The stretching temperature in the third step is preferably TgA - 5°C or higher, more preferably TgA or higher, preferably TgA + 30°C or lower, more preferably TgA + 25°C or lower, even more preferably TgA + 20°C or lower, and even more preferably TgA + 10°C or lower. Here, TgA represents the glass transition temperature of the resin contained in the resin layer (A) (preferably a resin containing a cyclic olefin polymer).

[0136] Furthermore, the stretching temperature in the third step is preferably TgB-80°C or higher, more preferably TgB-75°C or higher, particularly preferably TgB-70°C or higher, preferably TgB-20°C or lower, more preferably TgB-25°C or lower, and particularly preferably TgB-30°C or lower. Here, TgB represents the glass transition temperature of the resin containing a polymer containing N-vinylcarbazole monomer units in the resin layer (B).

[0137] The stretching in the third step is preferably performed by free uniaxial stretching. Here, free uniaxial stretching refers to stretching in one direction without applying any restraining force in directions other than the direction of stretching. Therefore, for example, free uniaxial stretching in the longitudinal direction of a multilayer film refers to stretching in the longitudinal direction without restraining the ends in the width direction of the multilayer film. By performing free uniaxial stretching in the third step, the slow axis directions of the first optical anisotropy layer and the second optical anisotropy layer can be easily controlled.

[0138] The stretching in the third step described above can be performed using, for example, a tenter stretcher or a roll stretcher, and it is preferable to use a roll stretcher. Free uniaxial stretching can be easily performed with a roll stretcher. Free uniaxial stretching using a roll stretcher is usually performed while continuously conveying a long multilayer film in the longitudinal direction. As a roll stretcher, for example, one described in International Publication No. 2016 / 047465 can be used.

[0139] <4.4. Optional Steps> The method for manufacturing the optically anisotropic laminate described above may include any additional steps in combination with the first, second, and third steps. For example, the method for manufacturing the optically anisotropic laminate may include a step of providing a protective layer on the surface of the optically anisotropic laminate. Furthermore, for example, the method for manufacturing the optically anisotropic laminate may include a step of applying a surface treatment such as corona treatment or plasma treatment to one or more surfaces of any layers such as resin layer (A), resin layer (B), and thin film at any point in time. Also, for example, the method may include a step of forming a thin film on resin layer (A) after the first step. The thin film can be formed, for example, by a method including applying a coating solution containing a resin as the material for the thin film and a solvent onto resin layer (A).

[0140] <5. Applications of Optically Anisotropic Laminates> The optically anisotropic laminate according to this embodiment can typically be combined with a linear polarizer to form a circular polarizer. By providing this circular polarizer on the display surface of an image display device, the reflection of ambient light can be reduced. With a circular polarizer including the optically anisotropic laminate described above, when viewing the display surface, the reflection of ambient light can be reduced, effectively reducing color distortion. This reduction in color distortion can be achieved in the inclined direction of the display surface, and usually also in the front direction of the display surface. Below, a circular polarizer using the optically anisotropic laminate according to this embodiment, and an image display device equipped with the circular polarizer will be described.

[0141] <5.1. Circular Polarizer> A circular polarizer may be provided with a linear polarizer, a first optical anisotropy layer, and a second optical anisotropy layer in this order, or with a linear polarizer, a second optical anisotropy layer, and a first optical anisotropy layer in this order, but the former is more preferred.

[0142] Furthermore, the angle between the absorption axis or transmission axis of the linear polarizer and the slow axis of the first optical anisotropy layer is preferably in a specific range close to 45°. Specifically, the angle is preferably 40° or more, more preferably 42° or more, even more preferably 43° or more, particularly preferably 44° or more, preferably 50° or less, more preferably 48° or less, even more preferably 47° or less, and particularly preferably 46° or less. In this case, furthermore, the angle between the absorption axis or transmission axis of the linear polarizer and the slow axis of the second optical anisotropy layer is preferably in a specific range close to 135°. Specifically, the angle is preferably 130° or more, more preferably 132° or more, even more preferably 133° or more, particularly preferably 134° or more, preferably 140° or less, more preferably 138° or less, even more preferably 137° or less, and particularly preferably 136° or less.

[0143] Any linear polarizer can be used as the linear polarizer. Examples of linear polarizers include films obtained by adsorbing iodine or a dichroic dye onto a polyvinyl alcohol film and then uniaxially stretching it in a boric acid bath; and films obtained by adsorbing iodine or a dichroic dye onto a polyvinyl alcohol film, stretching it, and further modifying some of the polyvinyl alcohol units in the molecular chain into polyvinylene units. Of these, a polarizer containing polyvinyl alcohol is preferred as the linear polarizer.

[0144] When natural light is incident on a linear polarizer, only one type of polarization is transmitted. The degree of polarization of this linear polarizer is not particularly limited, but is preferably 98% or higher, more preferably 99% or higher. The thickness of the linear polarizer is preferably 5 μm to 80 μm.

[0145] The circular polarizer described above may further include any additional layers. Examples of these additional layers include a polarizer protective film layer; an adhesive layer for bonding the linear polarizer and the optically anisotropic laminate; a hard coat layer such as an impact-resistant polymethacrylate resin layer; a matte layer to improve the film's slipperiness; an anti-reflective layer; an anti-fouling layer; an anti-static layer; and so on. These additional layers may be present individually or in pairs or in multiples.

[0146] <5.2. Image Display Devices> The circular polarizer described above can be provided in image display devices such as liquid crystal display devices and electroluminescent image display devices. In particular, it is preferable to provide the circular polarizer in an organic electroluminescent image display device. This organic electroluminescent image display device comprises a circular polarizer and an organic electroluminescent element (hereinafter, it may be appropriately referred to as an "organic EL element"). This organic electroluminescent image display device usually comprises a linear polarizer, an optically anisotropic laminate and an organic EL element in this order.

[0147] An organic EL element comprises a transparent electrode layer, an emissive layer, and an electrode layer in that order, and the emissive layer can emit light when a voltage is applied from the transparent electrode layer and the electrode layer. Examples of materials that constitute the organic emissive layer include poly(p-phenylenevinylene), polyfluorene, and polyvinylcarbazole materials. The emissive layer may also have a laminate of multiple layers with different emission colors, or a mixed layer in which a layer of one dye is doped with a different dye. Furthermore, the organic EL element may include functional layers such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, an equipotential surface forming layer, and a charge generation layer.

[0148] The aforementioned image display device can reduce the reflection of ambient light on the display surface. Specifically, when light incident from outside the device, only a portion of its linearly polarized light passes through the linear polarizer, and then passes through the optically anisotropic laminate, becoming circularly polarized light. The circularly polarized light is reflected by components that reflect light within the image display device (such as reflective electrodes in organic EL elements), and passes through the optically anisotropic laminate again, becoming linearly polarized light with a vibration direction perpendicular to the vibration direction of the incident linearly polarized light, and thus no longer passes through the linear polarizer. Here, the vibration direction of the linearly polarized light refers to the vibration direction of the electric field of the linearly polarized light. This achieves the function of reducing reflection.

[0149] Since the optically anisotropic laminate has the optical properties described above, the organic EL image display device can exhibit a reflection reduction function. This makes it possible to effectively reduce the reflection of ambient light from the display surface and reduce color distortion.

[0150] The degree of coloration is the color difference ΔE between the chromaticity measured by observing a reflective display surface and the chromaticity of a non-reflective black display surface. ＊ Chromaticity can be evaluated by ab. The aforementioned chromaticity is determined by measuring the spectrum of light reflected from the display surface, multiplying this spectrum by the spectral sensitivity (color matching function) corresponding to the human eye to obtain the tristimulus values ​​X, Y, and Z, and then determining the chromaticity (a ＊ , b ＊ , L ＊ This can be determined by calculating the color difference ΔE. ＊ ab is the chromaticity (a0) when the display surface is not illuminated by ambient light. ＊ , b0 ＊ , L0 ＊ ), and chromaticity when illuminated by ambient light (a1 ＊ , b1 ＊ , L1 ＊ ) can be obtained from the following equation (X).

[0151]

[0152] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0153] In the following explanation, "%" and "parts" refer to weight unless otherwise specified. Furthermore, the operations described below were performed under normal temperature and pressure (23°C, 1 atm) conditions in an atmospheric environment unless otherwise specified.

[0154] [Evaluation Method] (Thickness) The thickness of the laminate and each layer was measured using a film thickness measurement system (Filmetrics "F20").

[0155] (Measurement Method for Refractive Index, Phase Difference, and NZ Coefficient) The phase difference was measured using a phase difference meter (AxoScan, manufactured by Axometrics) at a temperature of 23°C. When determining the physical properties of each layer of an inseparable multilayer body, the measurement target was measured from multiple directions and calculated by fitting analysis using the accompanying multilayer analysis software. The measurement wavelength was 550 nm for the first and second optical anisotropic layers, and 450 nm, 550 nm, and 650 nm for the optical anisotropic laminate. The measurement wavelength for the refractive index and NZ coefficient of each layer was 550 nm.

[0156] (Measurement method for the slow phase axis direction) The direction of the slow phase axis of each layer constituting the multilayer film or optically anisotropic laminate was measured using a phase difference meter (AxoScan, manufactured by Axometrics). The direction of the slow phase axis relative to the longitudinal direction in a long multilayer film or optically anisotropic laminate was determined as the orientation angle.

[0157] (Glass transition temperature) The glass transition temperature was measured using a differential scanning calorimetry analyzer (for example, the "DSC6220" manufactured by S.I.I. Nanotechnology Co., Ltd.) in accordance with JIS K7121, under conditions of a heating rate of 10°C / min.

[0158] (Color difference ΔE from simulation) ＊ (Calculation of ab) Using "LCD Master" software manufactured by Syntec Corporation as the simulation software, the circular polarizers manufactured in each example and comparative example were modeled, and the following calculations were performed.

[0159] The following was set up as an evaluation model for simulation: - A circular polarizer is provided on the reflective surface of a mirror having a planar reflective surface. The mirror is an ideal mirror capable of specularly reflecting incident light with 100% reflectivity. - The circular polarizer has the same layer structure as obtained in each example and comparative example. The polarizer constituting the circular polarizer is a commonly used polarizer with a polarization degree of 99.99%, while the optically anisotropic laminate has the same optical properties as manufactured in each example and comparative example. - The circular polarizer is provided with its optically anisotropic laminate side facing the reflective surface. Therefore, the reflective surface, optically anisotropic laminate, and linear polarizer are arranged in this order.

[0160] Figure 2 is a schematic perspective view showing the evaluation model set up when calculating color space coordinates in the simulations for the examples and comparative examples. As shown in Figure 2, the color space coordinates observed on the reflective surface 10 of the mirror equipped with a circular polarizer were calculated when illuminated by a D65 light source (not shown). The color space coordinates when not illuminated by the light source were calculated as a0 ＊ = 0, b0 ＊ = 0, L0 ＊ We set it to = 0. Then, using the color space coordinates when (i) the light source is lit and (ii) the color space coordinates when the light source is not lit, we calculated the color difference ΔE using the aforementioned equation (X). ＊ We found ab.

[0161] The aforementioned color difference ΔE ＊ The calculation of ab is performed in the observation direction 20 where the polar angle ρ with respect to the reflective surface 10 is 0°, and the color difference ΔE in the front direction is calculated. ＊ ab was calculated. The polar angle ρ represents the angle that the reflection surface 10 makes with respect to the normal direction 11.

[0162] Furthermore, the aforementioned color difference ΔE ＊ The calculation of ab was performed in the observation direction 20 where the polar angle ρ with respect to the reflective surface 10 was 60°. This calculation at a polar angle ρ = 60° was performed multiple times by moving the observation direction 20 in the azimuth direction, with the azimuth angle φ moving in 5° increments within the range of 0° to less than 360°. The azimuth angle φ represents the angle that a direction parallel to the reflective surface 10 makes with a certain reference direction 12 parallel to the reflective surface 10. The color difference ΔE for the multiple observation directions 20 that were calculated was then calculated.＊ Calculate the average of ab and determine the color difference ΔE in the tilt direction with a polar angle ρ = 60°. ＊ We obtained ab.

[0163] (Method for visually evaluating a circular polarizer in the frontal direction) As an image display device equipped with a mirror, Apple's "AppleWatch" (registered trademark) (first generation) was prepared. The polarizer that was attached to the mirror of this image display device was peeled off, exposing the mirror. The surface of the mirror and the surface of the second optical anisotropy layer of the circular polarizer to be evaluated were bonded together via an adhesive layer (Nitto Denko's "CS9621").

[0164] On a sunny day, the circular polarizer was illuminated by sunlight, and the circular polarizer on the mirror was observed visually. The observation was performed in the front direction of the circular polarizer, at a polar angle of 0° and an azimuth angle of 0°. Based on the observation results, if chromatic colors were visible, it was judged as "B," and if no chromatic colors were visible, it was judged as "A."

[0165] (Visual Evaluation Method for Circular Polarizers in Inclined Directions) Apple's "AppleWatch" (registered trademark) was used as an image display device equipped with a mirror. The polarizer that was attached to the mirror of this image display device was peeled off, exposing the mirror. The surface of the mirror and the surface of the second optical anisotropy layer of the circular polarizer to be evaluated were bonded together via an adhesive layer (Nitto Denko's "CS9621"). On a sunny day, the circular polarizer was illuminated by sunlight, and the circular polarizer on the mirror was observed visually. The observation was performed in inclination directions of 60° polarity and 0° to 360° azimuth. Based on the observation results, the superiority of the reflectivity and coloration was comprehensively judged, and the examples and comparative examples were ranked. The ranked examples and comparative examples were then given points corresponding to their rank (1st place: 4 points, 2nd place: 3 points, 3rd place: 2 points, 4th place: 1 point).

[0166] Multiple people performed the aforementioned observations, and the total score was calculated for each example and comparative example based on the given points. The examples and comparative examples were arranged in order of their total scores, and the range of these total scores was divided into three equal parts, which were then evaluated in the order of A, B, and C from the highest-scoring group.

[0167] <Example 1> (First step: Production of resin layer (A)) Pelletized norbornene-based resin (manufactured by Nippon Zeon Co., Ltd.; glass transition temperature 126°C) was dried at 100°C for 5 hours. The dried resin was supplied to an extruder and extruded in a sheet form onto a casting drum from a T-die through a polymer pipe and polymer filter. The extruded resin was cooled to obtain a resin layer (A) as a long film with a thickness of 100 μm. The obtained film-like resin layer (A) was wound onto a roll and recovered.

[0168] (Second step: Formation of resin layer (B)) A resin solution containing poly(N-vinylcarbazole) (weight-average molecular weight Mw = 140,000, glass transition temperature 200°C, manufactured by Kanto Chemical Co., Ltd.) was prepared as a resin with negative intrinsic birefringence. This resin solution contained methyl ethyl ketone as a solvent, and its concentration in the poly(N-vinylcarbazole) resin solution was 15% by weight. A film-like resin layer (A) was pulled from the roll as a base film, and the above resin solution was coated onto this base film. The coated resin solution was then dried to form a layer of poly(N-vinylcarbazole) as resin layer (B) (thickness 4.8 μm) on the base film. This resulted in obtaining a multilayer film comprising a base film as resin layer (A) and a resin layer containing poly(N-vinylcarbazole) polymer as resin layer (B). The value of the phase difference Rth in the thickness direction of resin layer (B) was -95 nm. The obtained multilayer film was wound onto a roll and recovered.

[0169] (Third step: Stretching of multilayer film) The multilayer film was pulled from the roll and continuously fed into a longitudinal stretcher. The multilayer film was then uniaxially stretched in the longitudinal direction at an angle of 90° to the width direction of the multilayer film at a stretching temperature of 135°C and a stretching ratio of 1.35 times. As a result, an optically anisotropic laminate (broadband wavelength film) was obtained as a co-stretched film comprising a first optically anisotropic layer (λ / 2 layer) obtained by stretching the base film and a second optically anisotropic layer (λ / 4 layer) obtained by stretching the poly(N-vinylcarbazole) layer. In the obtained optically anisotropic laminate, the angle between the slow axis of the first optically anisotropic layer and the slow axis of the second optically anisotropic layer was 90°.

[0170] (Manufacturing of circular polarizers) A long linear polarizing film having an absorption axis in the longitudinal direction was prepared. This linear polarizing film and the aforementioned broadband wavelength film were bonded together such that their longitudinal directions were at a 45° angle. This bonding was performed using an adhesive (Nitto Denko Corporation's "CS-9621"). A circular polarizer was obtained having the linear polarizing film, a λ / 2 layer, and a λ / 4 layer in this order. The obtained circular polarizer was evaluated using the method described above.

[0171] <Example 2> In the first step, a resin layer (A) was obtained as a long film with a thickness of 110 μm by adjusting the resin extrusion conditions. In the second step, the conditions for coating the resin liquid onto the base film were adjusted, and the coated resin liquid was dried to form a resin layer (B) with a thickness of 5.8 μm on the base film. The value of the phase difference Rth in the thickness direction of the resin layer (B) was -115 nm. Except for the above, a circular polarizer was obtained by operating in the same manner as in Example 1, and the obtained circular polarizer was evaluated using the method described above.

[0172] <Comparative Example 1> In the second step, poly(2-vinylnaphthalene) (weight-average molecular weight Mw = 175,000, glass transition temperature 135°C, manufactured by Sigma-Aldrich) was used instead of poly(N-vinylcarbazole). The conditions for coating the resin liquid onto the substrate film were adjusted, and the coated resin liquid was dried to form a resin layer (B) with a thickness of 19.5 μm on the substrate film. The value of the phase difference Rth in the thickness direction of the resin layer (B) was -3 nm. Except for the above, an optically anisotropic laminate and a circular polarizer using the same were manufactured by the same procedure as in Example 1, and the obtained circular polarizer was evaluated by the method described above.

[0173] <Comparative Example 2> In the second step, poly(2-vinylnaphthalene) (weight-average molecular weight Mw = 175,000, glass transition temperature 135°C, manufactured by Sigma-Aldrich) was used instead of poly(N-vinylcarbazole). The conditions for coating the resin liquid onto the substrate film were adjusted, and the coated resin liquid was dried to form a resin layer (B) with a thickness of 23.7 μm on the substrate film. The value of the phase difference Rth in the thickness direction of the resin layer (B) was -4 nm. Except for the above, the optically anisotropic laminate and a circular polarizer using the same were manufactured by the same procedure as in Example 1, and the obtained circular polarizer was evaluated by the method described above.

[0174] The results are shown in Table 1. The abbreviations in Table 1 have the following meanings: "COP": norbornene-based resin (manufactured by Zeon Corporation; glass transition temperature 126°C) "PVCz": poly(N-vinylcarbazole) "PVN": poly(2-vinylnaphthalene) "TgA": glass transition temperature of the resin contained in resin layer (A) "TgB": glass transition temperature of the resin contained in resin layer (B) "NZ1": NZ coefficient of the first optical anisotropy layer "NZ2": NZ coefficient of the second optical anisotropy layer "NZ": NZ coefficient of the optical anisotropy laminate "θ １－２ ": The angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer.

[0175]

[0176] From the above results, it can be seen that the optical anisotropic laminate according to the example, which satisfies equations (1) to (5) and in which the second optical anisotropic layer contains a resin containing a polymer containing N-vinylcarbazole monomer units, can realize an image display device with reduced coloration of the display surface when viewed from the inclined direction. Furthermore, it can be seen that the optical anisotropic laminate according to the example can be manufactured efficiently with a small number of steps.

[0177] 10 Reflecting surface 11 Normal direction of the reflecting surface 12 Reference direction 20 Observation direction 100 Optically anisotropic laminate 110 First optically anisotropic layer 120 Second optically anisotropic layer A １１０ , A １２０ Late axis θ １－２ Angle φ Azimuth angle ρ Polar angle

Claims

1. An optically anisotropic laminate comprising a first optically anisotropic layer and a second optically anisotropic layer, wherein the first optically anisotropic layer satisfies the following formula (1); the second optically anisotropic layer satisfies the following formulas (2) and (3); the NZ coefficient NZ2 of the second optically anisotropic layer satisfies the following formula (4); the optically anisotropic laminate satisfies the following formula (5); and the second optically anisotropic layer comprises a resin containing a polymer containing N-vinylcarbazole monomer units. (1) nx1 > ny1 ≥ nz1 (2) nnz2 > nx2 > ny2 (3) Re2(550) > 100 nm (4) Re(450) < Re(550) < Re(650) (5) where nx1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that gives the maximum refractive index, ny1 represents the refractive index in the in-plane direction of the first optical anisotropy layer that is perpendicular to the direction that gives nx1, and nz1 represents the refractive index in the thickness direction of the first optical anisotropy layer; nx2 represents the refractive index in the in-plane direction of the second optical anisotropy layer that gives the maximum refractive index, ny2 represents the refractive index in the in-plane direction of the second optical anisotropy layer that is perpendicular to the direction that gives nx2, and nz2 represents the refractive index in the thickness direction of the second optical anisotropy layer; Re2(550) represents the in-plane phase difference of the second optical anisotropy layer at a wavelength of 550 nm; Re(450), Re(550), and Re(650) represent the in-plane phase differences of the optical anisotropy laminate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

2. The optically anisotropic laminate according to claim 1, wherein the first optically anisotropic layer comprises a resin containing a cyclic olefin polymer.

3. The optical anisotropic laminate according to claim 1, wherein the first optical anisotropic layer further satisfies the following formula (6): Re1(550) > 200 nm (6) where Re1(550) represents the in-plane phase difference of the first optical anisotropic layer at a wavelength of 550 nm.

4. The optical anisotropic laminate according to claim 1, wherein the angle between the slow axis of the first optical anisotropic layer and the slow axis of the second optical anisotropic layer is 85° to 95°.

5. A method for manufacturing an optically anisotropic laminate, comprising the steps in this order: a first step of preparing a resin layer (A) containing a resin containing a cyclic olefin polymer; a second step of forming a resin layer (B) on the resin layer (A) containing a resin containing a polymer containing N-vinylcarbazole monomer units to obtain a multilayer film; and a third step of stretching the multilayer film to obtain an optically anisotropic laminate including a first optically anisotropic layer which is a stretched layer of resin layer (A) and a second optically anisotropic layer which is a stretched layer of resin layer (B).

6. The method for producing an optically anisotropic laminate according to claim 5, wherein the second step comprises applying a resin solution containing a polymer containing the N-vinylcarbazole monomer units and an organic solvent onto the resin layer (A), and drying the applied resin solution.

7. The method for manufacturing an optically anisotropic laminate according to claim 5, wherein the phase difference Rth in the thickness direction of the resin layer (B) after the second step is -90 nm or less.

8. The method for producing an optically anisotropic laminate according to claim 5, wherein the glass transition temperature TgA of the resin containing the cyclic olefin polymer and the glass transition temperature TgB of the resin containing the polymer containing the N-vinylcarbazole monomer units satisfy the formula: TgB - TgA > 50°C; and the stretching of the multilayer film in the third step is carried out at a temperature of TgA - 5°C or higher and TgA + 10°C or lower.

9. A circular polarizer comprising the optically anisotropic laminate described in claim 1 and a linear polarizer.

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