Optical anisotropy layer

Abstract

The present invention provides an optically anisotropic layer which has two layers having different orientation states of a liquid crystal compound in the thickness direction and in which in-plane optical unevenness is reduced. An optically anisotropic layer of the present invention is formed by using a liquid crystal compound, the optically anisotropic layer having a first layer and a second layer along the thickness direction, the second layer being in direct contact with the first layer, wherein: the orientation state of the liquid crystal compound in the first layer is different from the orientation state of the liquid crystal compound in the second layer; a region within the largest square which can be drawn on the surface of the optically anisotropic layer is subdivided into 64 square subregions of the same area; the thickness d1 of the first layer and the thickness d2 of the second layer at the center position of the sub-region are obtained, and X represented by expression (1) is calculated for each sub-region; and among 64 calculated Xs, the relationship of expression (2A) is satisfied, the maximum value is Xmax, and the minimum value is Xmin.　Expression (1) X = d1 / (d1 + d2) Expression (2A) Xmax / Xmin < 1.10

Description

[Technical Field]

[0001] This invention relates to an optically anisotropic layer. [Background technology]

[0002] Phase difference layers (optical anisotropy layers) with refractive index anisotropy are applied to various applications such as anti-reflective coatings for display devices and optical compensation films for liquid crystal display devices. As an optical anisotropy layer, a laminated optical anisotropy layer consisting of multiple layers is disclosed, as described in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5960743 [Overview of the project] [Problems that the invention aims to solve]

[0004] The inventors of the present invention have investigated the properties of conventional laminated optical anisotropy layers and found that optical unevenness occurs within the plane. Optical anisotropy layers with such in-plane optical unevenness cause various problems when applied to various applications. For example, if an optically anisotropic layer having optical unevenness within its surface and functioning as a λ / 4 plate is applied to a circular polarizer for anti-reflective purposes in an organic electroluminescent display device, color unevenness in the organic EL display device becomes visible. Furthermore, in the case of an optically anisotropic layer having optical unevenness within its surface, unevenness in reflected color within the surface becomes visible.

[0005] In view of the above circumstances, the present invention aims to provide an optically anisotropic layer having two layers with different orientation states of liquid crystal compounds in the thickness direction, thereby suppressing optical unevenness in the plane. [Means for solving the problem]

[0006] The inventors of this invention have diligently studied the problems of the prior art and have found that the above problems can be solved by the following configuration.

[0007] (1) An optically anisotropic layer formed using a liquid crystal compound, The optically anisotropic layer has a first layer and a second layer that is in direct contact with the first layer, along the thickness direction. The orientation state of the liquid crystal compound in the first layer is different from the orientation state of the liquid crystal compound in the second layer. An optically anisotropic layer is constructed by subdividing the largest possible square area that can be drawn on the surface of the optically anisotropic layer into 64 square sub-regions of the same area, determining the thickness d1 of the first layer and the thickness d2 of the second layer at the center of each sub-region, calculating X represented by equation (1) for each sub-region, and then, among the 64 calculated X values, taking the maximum value as Xmax and the minimum value as Xmin, satisfying the relationship in equation (2A). Formula (1) X=d1 / (d1+d2) Formula (2A) Xmax / Xmin<1.10 (2) The optical anisotropy layer described in (1) that satisfies the relationship in equation (2B). Formula (2B) Xmax / Xmin<1.09 (3) The first layer is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, The optical anisotropic layer according to (1) or (2), wherein the second layer is a layer in which the orientation state of a liquid crystal compound that is twisted along a helical axis extending in the thickness direction is fixed. (4) The first and second layers are layers in which the orientation state of a liquid crystal compound that is twisted along a helical axis extending in the thickness direction is fixed, The optical anisotropic layer according to (1) or (2), wherein the twist angle of the liquid crystal compound in the first layer is different from the twist angle of the liquid crystal compound in the second layer. (5) The first and second layers are optically anisotropic layers in which a cholesteric liquid crystal phase is fixed, An optical anisotropic layer according to (1) or (2), wherein the helical pitch of the cholesteric liquid crystal phase in the first layer is different from the helical pitch of the cholesteric liquid crystal phase in the second layer. (6) The first and second layers are optically anisotropic layers in which the orientation state of the liquid crystal compound is fixed, An optically anisotropic layer according to (1) or (2), wherein the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the first layer is different from the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the second layer. (7) The first layer is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, The optical anisotropic layer according to (1) or (2), wherein the second layer is a layer in which the orientation state of a homeotropically oriented liquid crystal compound is fixed. (8) The first layer is a layer in which the orientation state of the liquid crystal compound is fixed, The optical anisotropic layer according to (1) or (2), wherein the second layer is a layer in which the liquid crystal compound is fixed in an isotropic phase state. [Effects of the Invention]

[0008] In the present invention, an optically anisotropic layer is provided which has two layers in which the orientation state of the liquid crystal compound differs in the thickness direction, thereby suppressing optical unevenness in the plane. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing an example of a conventional stacked optical anisotropy layer. [Figure 2] This is a cross-sectional view showing an example of the optical anisotropy layer of the present invention. [Figure 3] This is a top view of the optically anisotropic layer to explain the relationship in equation (2A). [Figure 4] This is a cross-sectional view of the optically anisotropic layer within a sub-region. [Figure 5] This is a cross-sectional view showing an example of a first embodiment of the optical anisotropy layer. [Figure 6]This is a cross-sectional view of a composition layer illustrating an example of step 3A in the manufacturing method of the first embodiment of the optically anisotropic layer. [Figure 7] This is a cross-sectional view of a composition layer illustrating an example of step 4A in the manufacturing method of the first embodiment of the optically anisotropic layer. [Figure 8] This is a schematic diagram of a graph plotting the relationship between helical twisting power (HTP) (μm-1) × concentration (mass%) and light irradiation dose (mJ / cm2) for each of chiral agents A and B. [Figure 9] This is a schematic diagram of a graph plotting the relationship between the weighted average helical induced force (μm-1) and the light irradiation dose (mJ / cm2) in a system using both chiral agent A and chiral agent B. [Figure 10] This is a cross-sectional view showing an example of a second embodiment of the optical anisotropy layer. [Figure 11] This is a cross-sectional view of a composition layer illustrating a manufacturing method for a second embodiment of the optically anisotropic layer. [Figure 12] This is a cross-sectional view of a composition layer illustrating a manufacturing method for a second embodiment of the optically anisotropic layer. [Figure 13] This is a cross-sectional view showing an example of a third embodiment of the optical anisotropy layer. [Figure 14] This is a cross-sectional view of a composition layer illustrating an example of step 3B of the manufacturing method of the third embodiment of the optically anisotropic layer. [Figure 15] This is a cross-sectional view of a composition layer illustrating an example of step 4B of the manufacturing method of the third embodiment of the optically anisotropic layer. [Figure 16] This is a schematic diagram of a graph plotting the relationship between helical twisting power (HTP) (μm-1) and light irradiation dose (mJ / cm2) for chiral agent A. [Figure 17] This is a cross-sectional view showing an example of a fourth embodiment of the optical anisotropy layer. [Figure 18] This is a cross-sectional view of a composition layer illustrating an example of step 3C in the manufacturing method of the fourth embodiment of the optically anisotropic layer. [Figure 19]This is a cross-sectional view of a composition layer illustrating an example of step 4C in the manufacturing method of the fourth embodiment of the optically anisotropic layer. [Figure 20] This is a cross-sectional view showing an example of a fifth embodiment of the optical anisotropy layer. [Figure 21] This is a cross-sectional view of a composition layer illustrating an example of step 3D of the manufacturing method of the fifth embodiment of the optically anisotropic layer. [Figure 22] This is a cross-sectional view of a composition layer illustrating an example of step 4D of the manufacturing method of the fifth embodiment of the optically anisotropic layer. [Figure 23] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 24] This is a cross-sectional view showing one embodiment of the polarizer-equipped optical anisotropy layer of the present invention. [Modes for carrying out the invention]

[0010] The present invention will now be described in detail. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. First, the terms used in this specification will be explained.

[0011] Unless otherwise specified, the slow axis is defined at 550 nm.

[0012] In this invention, Re(λ) and Rth(λ) represent the in-plane retardation and thickness-direction retardation at wavelength λ, respectively. Unless otherwise specified, wavelength λ is 550 nm. In this invention, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using AxoScan (manufactured by Axometrics). By inputting the average refractive index ((nx+ny+nz) / 3) and film thickness (d(μm)) into AxoScan, Slow axis direction (°) Re(λ)=R0(λ) Rth(λ)=((nx+ny) / 2-nz)×d This is calculated. Note that R0(λ) is a value displayed by AxoScan, and it means Re(λ).

[0013] In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Corporation) with a sodium lamp (λ=589nm) as the light source. Furthermore, when measuring wavelength dependence, it can be measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Corporation) in combination with an interference filter. Additionally, values ​​from the Polymer Handbook (JOHN WILEY & SONS, INC.) and catalogs of various optical films can be used. Examples of average refractive index values ​​for major optical films are given below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0014] In this specification, "light" means active light or radiation, such as the emission spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light (EUV light), X-rays, ultraviolet light, and electron beams (EB). Of these, ultraviolet light is preferred.

[0015] In this specification, "visible light" refers to light in the range of 380 to 780 nm. Furthermore, unless otherwise specified, the measurement wavelength is 550 nm. In this specification, when the liquid crystal compound is torsionally oriented in the optically anisotropic layer, the torsion angle is preferably greater than 0° and less than 360°. The cholesteric liquid crystal phase, described later, is a phase having a periodic structure in which the liquid crystal compound is spirally oriented, and its torsion angle is 360° or more.

[0016] A key feature of the optical anisotropy layer of the present invention is that it controls the relationship between the thickness of the first layer (described later) and the thickness of the second layer (described later) in the in-plane direction of the optical anisotropy layer. The present inventors, after examining the prior art, discovered for the first time that variations in the thickness of the layers forming the optical anisotropy layer are influential in causing optical unevenness within the plane of a stacked optical anisotropy layer. More specifically, Figure 1 shows an example of a stacked optical anisotropy layer of the prior art. In the optical anisotropy layer 100 shown in Figure 1, which is formed by stacking a first layer 102 and a second layer 104, for example, if the thickness of the first layer 102 at position X is dX1 and the thickness of the second layer 104 is d2X, and the thickness of the first layer 102 at position Y is d1Y and the thickness of the second layer 104 is d2Y, then d1X and d1Y, and d2X and d2Y differ significantly, resulting in differences between the optical properties at position X and position Y, thus causing optical unevenness within the plane. In conventional technology, the above-mentioned large variations in thickness can occur for several reasons. For example, when forming the first and second layers by sequential coating, if the composition used to form the first layer does not contain a leveling agent, the surface tension of the first layer can easily cause unevenness, resulting in the above-mentioned structure. Additionally, when light irradiation is performed to fix the orientation state of the liquid crystal compound, a large distribution of irradiation dose within the irradiation range can also easily lead to the above-mentioned structure. In other words, when light irradiation occurs, if there are areas where the irradiation dose is high and curing progresses easily, and areas where the irradiation dose is low and curing progresses slowly, the above-mentioned structure is likely to occur. The inventors of this invention have for the first time discovered that the optical unevenness within the plane described above is caused by variations in the thickness of each layer, and have found that the desired effect can be obtained by controlling the thickness of each layer to a predetermined range.

[0017] The optically anisotropic layer (multilayer film) of the present invention will be described in detail below. The optically anisotropic layer of the present invention is a layer formed using a liquid crystal compound and exhibits optical anisotropy. As will be described later, the optically anisotropic layer of the present invention may include a layer that does not exhibit optical anisotropy. In other words, the optically anisotropic layer of the present invention has a first layer and a second layer as will be described later, and it is sufficient that at least one of the two layers is an optically anisotropic layer, while the other of the two layers may be a layer that does not exhibit optical anisotropy. The optically anisotropic layer of the present invention may be formed using a liquid crystal compound, and is preferably a layer in which a liquid crystal compound is immobilized. Specific embodiments of the optically anisotropic layer include the first to fifth embodiments described later, which will be explained in detail in the following section.

[0018] The optically anisotropic layer may contain materials other than liquid crystal compounds. Other materials include other components that may be included in the composition for forming the optically anisotropic layer, as described later. Details will be provided later.

[0019] The optically anisotropic layer has a first layer and a second layer in direct contact with the first layer, along the thickness direction. More specifically, as shown in Figure 2, the optically anisotropic layer 10 has a first layer 12 and a second layer 14. The orientation state of the liquid crystal compound in the first layer is different from the orientation state of the liquid crystal compound in the second layer. A different orientation state of the liquid crystal compound means, for example, that in one of the first or second layers, the liquid crystal compound is not oriented (isotropic phase), while in the other layer, the liquid crystal compound is oriented to form a predetermined liquid crystal phase. Furthermore, even if both the first and second layers are oriented to form a predetermined liquid crystal phase, the orientation state is considered different if the type of liquid crystal phase, orientation direction, and twist angle differ. Specific examples of different orientation states of the liquid crystal compound include the first to fifth embodiments described later.

[0020] The optical anisotropy layer of the present invention satisfies the relationship shown in equation (2A), which will be described later. The relationship in equation (2A) will be explained in detail below with reference to the drawings. Figure 3 is a top view of the optical anisotropy layer 10, and is a diagram showing the optical anisotropy layer 10 as observed from the white arrow in Figure 2. In Figure 3, the surface shape of the optical anisotropy layer 10 is square. However, as will be described later, the surface shape of the optical anisotropy layer 10 is not limited to the form shown in Figure 3. First, draw the largest possible square on the surface of the optically anisotropic layer. As mentioned above, in Figure 3, since the surface shape of the optically anisotropic layer 10 is square, it is possible to draw a square that covers the entire surface of the optically anisotropic layer 10. Next, as shown in Figure 3, the drawn square is subdivided into 64 square-shaped sub-regions of the same area. That is, as shown in Figure 3, dashed lines are drawn to divide the vertical side of the drawn square (the side extending in the vertical direction in Figure 3) into 8 equal parts, and dashed lines are also drawn to divide the horizontal side of the drawn square (the side extending in the horizontal direction in Figure 3) into 8 equal parts, thereby subdividing the drawn square into 64 square-shaped sub-regions 16 of the same area.

[0021] Next, we determine the thickness d1 of the first layer and the thickness d2 of the second layer at the center of each sub-region. Taking the upper left sub-region 16 in Figure 3 as an example, first, we determine the center position CP within the sub-region 16, as shown in Figure 3. The center position CP is located at the center of the square-shaped sub-region 16. More specifically, the center position is defined as the point where the two diagonals of the square-shaped sub-region 16 intersect. Next, as shown in Figure 4, the thickness d1 of the first layer and the thickness d2 of the second layer at the central position CP of the sub-region 16 are determined. One method for calculating these thicknesses is to cut the optically anisotropic layer along a line passing through the central position CP and observe the cross-section of the exposed optically anisotropic layer with a polarizing microscope.

[0022] Perform the above procedure for each sub-region and calculate X, which is expressed by equation (1) for each sub-region. Formula (1) X=d1 / (d1+d2) Next, among the 64 calculated X values ​​(X for each of the 64 sub-regions), when the maximum value is Xmax and the minimum value is Xmin, the optical anisotropic layer of the present invention has an Xmax / Xmin ratio of less than 1.10, as shown in equation (2A). Formula (2A) Xmax / Xmin<1.10

[0023] Furthermore, it is preferable that the relationship shown in equation (2B) is satisfied, in that optical unevenness within the plane is further suppressed (hereinafter also simply referred to as "the point in which the effects of the present invention are superior"). Formula (2B) Xmax / Xmin<1.09 There are no specific lower limits on the Xmax / Xmin ratio, but it is often greater than 1.00. If Xmax and Xmin are the same, Xmax / Xmin is set to 1.00.

[0024] The method for manufacturing an optically anisotropic layer that satisfies the relationship in equation (2A) above is not particularly limited, but one example is a method that suppresses variations in the amount of irradiation in the area (in-plane) where light is irradiated during light irradiation. Examples of methods that suppress variations in the amount of irradiation include adjusting the output of the light source to adjust the amount of irradiation in the plane, or placing a filter between the light source and the irradiated object in areas with high irradiation to adjust the amount of irradiation in the plane. In particular, a key advantage of the present invention is that the difference between the maximum and minimum irradiation doses in the irradiation area during light irradiation is 1.0 mJ / cm². 2 Preferably, it is 0.7 mJ / cm². 2 The following is more preferable. There are no particular restrictions on the lower limit, but 0 is a possible value. Furthermore, the ratio of the maximum irradiation dose to the minimum irradiation dose (maximum irradiation dose / minimum irradiation dose) is preferably 1.10 or less, and more preferably 1.05 or less, in terms of achieving superior effects of the present invention. The lower limit is not particularly limited, but 1 is an example. In other words, it is preferable that the irradiation dose is constant within the plane.

[0025] As mentioned above, Figure 3 shows an embodiment in which the surface shape of the optical anisotropy layer 10 is square, but the embodiment is not limited to this. For example, the surface shape of the optical anisotropy layer 10 may be rectangular, elliptical, trapezoidal, or amorphous.

[0026] The thickness of the optical anisotropy layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and even more preferably 0.2 to 6.0 μm. The ratio of the thickness of the first layer to the thickness of the second layer (thickness of the first layer / thickness of the second layer) is not particularly restricted, but it is often between 0.1 and 5.0, and more often between 0.2 and 3.0.

[0027] As described above, the optically anisotropic layer has a first layer and a second layer in which the orientation states of the liquid crystal compounds are different from each other. The embodiments of the first and second layers are not particularly limited, but the following first to fifth embodiments are preferred. First embodiment: The first layer is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, and the second layer is a layer in which the orientation state of a torsionally oriented liquid crystal compound along a helical axis extending in the thickness direction is fixed. Second implementation: The first and second layers are layers in which the orientation state of liquid crystal compounds that are twisted and oriented along a helical axis extending in the thickness direction is fixed, and the twist angle of the liquid crystal compound in the first layer is different from the twist angle of the liquid crystal compound in the second layer. Third embodiment: The first and second layers are optically anisotropic layers with a fixed cholesteric liquid crystal phase, wherein the helical pitch of the cholesteric liquid crystal phase in the first layer and the helical pitch of the cholesteric liquid crystal phase in the second layer are different. Fourth implementation: The first and second layers are optically anisotropic layers in which the orientation state of the liquid crystal compound is fixed, and the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the first layer is different from the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the second layer. Fifth implementation: The first layer is a layer in which the liquid crystal compound is oriented in a fixed orientation state, and the second layer is a layer in which the liquid crystal compound exhibits an isotropic phase state. The first to fifth embodiments described above will be explained in detail below.

[0028] In this specification, the most typical and preferred embodiment of the "fixed" state is a state in which the orientation of the liquid crystal compound is maintained. However, it is not limited to this, and more specifically, it is more preferable that the layer is non-fluid and that the fixed orientation can be stably maintained without causing changes in the orientation due to external fields or external forces, typically in a temperature range of 0 to 50°C, and under more severe conditions, in a temperature range of -30 to 70°C. Furthermore, in the optically anisotropic layer, the composition within the layer does not ultimately need to exhibit liquid crystalline properties.

[0029] <<First Embodiment>> In the first embodiment of the optically anisotropic layer, the first layer is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, and the second layer is a layer in which the orientation state of a liquid crystal compound that is twisted along a helical axis extending in the thickness direction is fixed. Figure 5 shows an example of the first embodiment of the optically anisotropic layer. The optically anisotropic layer 200 shown in Figure 5 is an optically anisotropic layer formed using a liquid crystal compound LC, and has a first layer 200A and a second layer 200B along the thickness direction. The first layer 200A is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, and the second layer 200B is a layer in which the orientation state of a torsionally oriented liquid crystal compound along a helical axis extending along the thickness direction is fixed. The orientation of the liquid crystal compound in the second layer 200B may be left-handed (counterclockwise) or right-handed (clockwise).

[0030] In this specification, homogeneous orientation refers to a state in which the molecular axes of a liquid crystal compound (for example, the long axis in the case of a rod-shaped liquid crystal compound) are aligned horizontally and in the same direction with respect to the surface of the composition layer (optical uniaxiality). Here, "horizontal" does not require strict horizontal alignment, but rather means an orientation in which the average molecular axis of the liquid crystal compound within the composition layer makes an inclination angle of less than 20° with respect to the surface of the composition layer. Furthermore, "same orientation" does not require that the orientations be strictly the same, but rather means that when the orientation of the lagging axis is measured at any 20 locations in the plane, the maximum difference between the lagging axis orientations at those 20 locations (the difference between the two lagging axis orientations with the largest difference out of the 20 lagging axis orientations) is less than 10°.

[0031] In the first embodiment, if the thickness of the first layer is d1 and the refractive index anisotropy of the first layer measured at a wavelength of 550 nm is Δn1, it is preferable that the first layer satisfies the following equation (1A-1) in such a way that the optical anisotropy layer can be suitably applied to a circular polarizing plate. Formula (1A-1) 100nm≦Δn1d1≦240nm In particular, it is more preferable that equation (1A-2) is satisfied, and even more preferable that equation (1A-3) is satisfied. Formula (1A-2) 120nm≦Δn1d1≦220nm Formula (1A-3) 140nm≦Δn1d1≦200nm

[0032] In the first embodiment, when the thickness of the second layer is d2 and the refractive index anisotropy of the second layer measured at a wavelength of 550 nm is Δn2, it is preferable that the second layer satisfies the following equation (2A-1) in order to suitably apply the optical anisotropy layer to a circular polarizer. Formula (2A-1) 100nm≦Δn2d2≦240nm In particular, it is more preferable that equation (2A-2) is satisfied, and even more preferable that equation (2A-3) is satisfied. Formula (2A-2) 120nm≦Δn2d2≦220nm Formula (2A-3) 140nm≦Δn2d2≦200nm

[0033] The absolute value of the torsion angle of the liquid crystal compound in the second layer is not particularly limited, but 50 to 110° is preferred, and 60 to 100° is more preferred, in that the optically anisotropic layer can be suitably applied to a circular polarizing plate. First, when we say that a liquid crystal compound is torsion-oriented, we mean that the liquid crystal compound twists around the thickness direction of the second layer, from one surface of the second layer (the surface on the first layer side in Figure 5) to the other surface (the surface opposite to the first layer side in Figure 5). Therefore, the torsion angle refers to the angle between the molecular axis of the liquid crystal compound on one surface of the second layer (the long axis in the case of a rod-shaped liquid crystal compound) and the molecular axis of the liquid crystal compound on the other surface of the second layer. The torsional angle is measured using Axometrics' Axoscan and their instrument analysis software.

[0034] The first embodiment of the optically anisotropic layer preferably exhibits inverse wavelength dispersion. In other words, it is preferable that the in-plane retardation Re(450) measured at a wavelength of 450 nm of the optical anisotropy layer, Re(550) measured at a wavelength of 550 nm of the optical anisotropy layer, and Re(650) measured at a wavelength of 650 nm of the optical anisotropy layer satisfy the relationship Re(450) ≤ Re(550) ≤ Re(650).

[0035] The optical properties of the first embodiment of the optical anisotropy layer are not particularly limited, but it is preferable that it functions as a λ / 4 plate. A λ / 4 plate is a plate that has the function of converting linearly polarized light of a specific wavelength to circularly polarized light (or circularly polarized light to linearly polarized light), and is a plate (optical anisotropic layer) in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ)=λ / 4. This equation only needs to be achieved at any wavelength in the visible light range (for example, 550 nm), but it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship 110 nm ≤ Re(550) ≤ 180 nm.

[0036] The method for manufacturing the first embodiment of the optical anisotropy layer is not particularly limited, but a manufacturing method having the following steps 1A to 5A is preferred. Step 1A: A step to form a composition layer containing a chiral agent that includes at least a photosensitive chiral agent whose helical induced force changes upon light irradiation, and a liquid crystal compound having polymerizable groups. Step 2A: A step in which the composition layer is subjected to heat treatment to orient the liquid crystal compound in the composition layer. Step 3A: After Step 2A, under conditions of an oxygen concentration of 1 volume% or more, the composition layer is irradiated with light for 50 seconds or less and at a concentration of 300 mJ / cm². 2 The following steps Step 4A: After step 3A, the composition layer is subjected to heat treatment at a higher temperature than that during light irradiation. Step 5A: After Step 4A, a curing treatment is performed on the composition layer to form an optically anisotropic layer. As described later, in the first embodiment, in order to produce an optically anisotropic layer with the above characteristics, the total content of chiral agents in the composition layer (total content of all chiral agents) is preferably 5.0% by mass or less with respect to the total mass of the liquid crystal compound. The following details the procedures for each of the above steps.

[0037] <Process 1A> Step 1A is a step of forming a composition layer containing a chiral agent that includes at least a photosensitive chiral agent whose helical induced force changes upon light irradiation, and a liquid crystal compound having polymerizable groups. By performing this step, a composition layer that will be subjected to the light irradiation treatment described later is formed. Below, we will first describe in detail the materials used in this process, and then describe in detail the procedure of the process.

[0038] (Chiral agent) The composition layer of step 1A contains a chiral agent that includes at least a photosensitive chiral agent whose helical induced force changes upon light irradiation. First, the photosensitive chiral agent whose helical induced force changes upon light irradiation will be described in detail. Furthermore, the helical induced force (HTP) of a chiral agent is a factor that indicates the helical orientation ability, represented by the following formula (A). Formula (A) HTP = 1 / (Helical pitch length (unit: μm) × Concentration of chiral agent relative to liquid crystal compound (mass %)) [μm -1 ] The length of the helical pitch refers to the length of the pitch P (= period of the helix) of the helical structure of the cholesteric liquid crystal phase, and can be measured using the method described on page 196 of the Liquid Crystal Handbook (published by Maruzen Co., Ltd.).

[0039] A photosensitive chiral agent whose helical induced force changes upon light irradiation (hereinafter also simply referred to as "chiral agent A") may be liquid crystalline or non-liquid crystalline. Chiral agent A generally contains an asymmetric carbon atom. However, chiral agent A may also be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom.

[0040] Chiral agent A may be a chiral agent whose helical-inducing force increases or decreases upon light irradiation. In particular, it is preferable that the chiral agent is one whose helical-inducing force decreases upon light irradiation. In this specification, "increase and decrease in helical induced force" refers to the increase or decrease when the initial (before light irradiation) helical direction of chiral agent A is considered "positive". Therefore, even if the helical induced force continues to decrease due to light irradiation and exceeds 0, resulting in a "negative" helical direction (i.e., inducing a helical direction opposite to the initial (before light irradiation) helical direction), it still falls under the category of a "chiral agent whose helical induced force decreases".

[0041] Chiral agent A is a so-called photoreactive chiral agent. A photoreactive chiral agent is a compound that has a chiral site and a photoreactive site that changes structure upon light irradiation, and for example, it greatly changes the torsional force of a liquid crystal compound depending on the amount of irradiation. Examples of photoreactive sites that undergo structural changes upon light irradiation include photochromic compounds (Kingo Uchida, Masahiro Irie, Chemical Industry, vol. 64, 640p, 1999; Kingo Uchida, Masahiro Irie, Fine Chemical, vol. 28(9), 15p, 1999). The above structural changes refer to decomposition, addition reactions, isomerization, racemization, [2+2] photocyclization, and dimerization reactions that occur upon light irradiation of the photoreactive site, and these structural changes may be irreversible. Chiral sites include, for example, the chiral carbon described in Hiroyuki Nodaira, Chemical Review, No. 22 Chemistry of Liquid Crystals, 73p: 1994.

[0042] Examples of chiral agent A include the photoreactive chiral agent described in paragraphs 0044-0047 of Japanese Patent Publication No. 2001-159709, the optically active compound described in paragraphs 0019-0043 of Japanese Patent Publication No. 2002-179669, the optically active compound described in paragraphs 0020-0044 of Japanese Patent Publication No. 2002-179633, the optically active compound described in paragraphs 0016-0040 of Japanese Patent Publication No. 2002-179670, the optically active compound described in paragraphs 0017-0050 of Japanese Patent Publication No. 2002-179668, and the optically active compound described in paragraphs 0018-00 of Japanese Patent Publication No. 2002-180051. The optically active compounds described in 44, the optically active isosorbide derivatives described in paragraphs 0016 to 0055 of Japanese Patent Publication No. 2002-338575, the photoreactive optically active compounds described in paragraphs 0023 to 0032 of Japanese Patent Publication No. 2002-080478, the photoreactive chiral agents described in paragraphs 0019 to 0029 of Japanese Patent Publication No. 2002-080851, the optically active compounds described in paragraphs 0022 to 0049 of Japanese Patent Publication No. 2002-179681, the optically active compounds described in paragraphs 0015 to 0044 of Japanese Patent Publication No. 2002-302487, and Japanese Patent Publication No. 2002-338668 Optically active polyesters described in paragraphs 0015 to 0050 of the report, binaphthol derivatives described in paragraphs 0019 to 0041 of JP 2003-055315, optically active fulgid compounds described in paragraphs 0008 to 0043 of JP 2003-073381, optically active isosorbide derivatives described in paragraphs 0015 to 0057 of JP 2003-306490, optically active isosorbide derivatives described in paragraphs 0015 to 0041 of JP 2003-306491, optically active Examples include optically active isosorbide derivatives, optically active isomannide derivatives described in paragraphs 0015 to 0057 of Japanese Patent Publication No. 2003-313188, optically active isosorbide derivatives described in paragraphs 0015 to 0049 of Japanese Patent Publication No. 2003-313189, optically active polyester / amides described in paragraphs 0015 to 0052 of Japanese Patent Publication No. 2003-313292, optically active compounds described in paragraphs 0012 to 0053 of Japanese Patent Publication No. WO2018 / 194157, and optically active compounds described in paragraphs 0020 to 0049 of Japanese Patent Publication No. 2002-179682.

[0043] Among the chiral agents A, compounds having at least a photoisomerization site are preferred, and it is more preferable that the photoisomerization site has a photoisomerizable double bond. As the photoisomerization site having the photoisomerizable double bond, the cinnamoyl site, chalcone site, azobenzene site, or stilbene site are preferred in that photoisomerization occurs easily and the difference in helical induced force before and after light irradiation is large, and the cinnamoyl site, chalcone site, or stilbene site is even more preferred in that it absorbs less visible light. The photoisomerization site corresponds to the photoreaction site that undergoes structural changes upon light irradiation as described above.

[0044] Furthermore, it is preferable that chiral agent A has a trans-type photoisomerizable double bond, as it exhibits high initial (pre-light irradiation) helical induction force and a superior change in helical induction force due to light irradiation. Furthermore, it is preferable that chiral agent A has a cis-type photoisomerizable double bond, as it exhibits low initial (pre-light irradiation) helical induction force and a superior change in helical induction force due to light irradiation.

[0045] Chiral agent A preferably has a substructure selected from a binaphthyl substructure, an isosorbide substructure (a substructure derived from isosorbide), and an isomannide substructure (a substructure derived from isomannide). The binaphthyl substructure, isosorbide substructure, and isomannide substructure are intended to have the following structures, respectively. In the binaphthyl substructure, the parallel solid and dashed lines represent single or double bonds. In the structures shown below, * indicates a bond position.

[0046] [ka]

[0047] Chiral agent A may have a polymerizable group. The type of polymerizable group is not particularly limited, but functional groups capable of addition polymerization are preferred, polymerizable ethylenically unsaturated groups or cyclic polymerizable groups are more preferred, and (meth)acryloyl groups, vinyl groups, styryl groups, or allyl groups are even more preferred.

[0048] As the chiral agent A, a compound represented by formula (C) is preferred. Formula (C) RLR Each R independently represents a group having at least one moiety selected from the group consisting of a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, and a stilbene moiety. L represents a divalent linking group formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linking group formed by removing two hydrogen atoms from the binaphthyl substructure), a divalent linking group represented by formula (E) (a divalent linking group consisting of the isosorbide substructure), or a divalent linking group represented by formula (F) (a divalent linking group consisting of the isomannide substructure). In equations (E) and (F), * indicates a bonding position.

[0049] [ka]

[0050] In step 1A, at least one of the chiral agents A described above is used. Step 1A may also involve using two or more types of chiral agents A, or it may involve using at least one type of chiral agent A and at least one type of chiral agent whose helical induced force does not change upon light irradiation (hereinafter also simply referred to as "chiral agent B"). Chiral agent B may be liquid crystalline or non-liquid crystalline. Chiral agent B generally contains an asymmetric carbon atom. However, chiral agent B may be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom. Chiral agent B may have polymerizable groups. Examples of polymerizable groups include those that chiral agent A may have. Any known chiral agent can be used as chiral agent B. It is preferable that chiral agent B is a chiral agent that induces a helix in the opposite direction to that of chiral agent A. That is, for example, if the helix induced by chiral agent A is in the rightward direction, the helix induced by chiral agent B will be in the leftward direction.

[0051] The molar extinction coefficients of chiral agent A and chiral agent B are not particularly limited, but the molar extinction coefficient at the wavelength of light irradiated in step 3A described later (e.g., 365 nm) is preferably 100 to 100,000 L / (mol·cm), and more preferably 500 to 50,000 L / (mol·cm).

[0052] The respective contents of chiral agent A and chiral agent B in the composition layer can be appropriately set according to the characteristics of the optically anisotropic layer to be formed (e.g., retardation and wavelength dispersion). Furthermore, since the torsion angle of the liquid crystal compound in the optically anisotropic layer depends greatly on the type and concentration of chiral agent A and chiral agent B, the orientation state of the liquid crystal compound can be controlled by adjusting these.

[0053] In the first embodiment, the total content of chiral agents in the composition layer (total content of all chiral agents) is not particularly limited, but in terms of ease of controlling the orientation state of the liquid crystal compound, it is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less, relative to the total mass of the liquid crystal compound. The lower limit is not particularly limited, but it is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass.

[0054] The content of chiral agent A in the chiral agent is not particularly limited, but it is preferably 5 to 95% by mass and more preferably 10 to 90% by mass relative to the total mass of the chiral agent, as this makes it easier to control the orientation state of the liquid crystal compound.

[0055] (liquid crystal compound) The composition layer of step 1A contains a liquid crystal compound having polymerizable groups. There are no particular restrictions on the type of liquid crystal compound used. Generally, liquid crystal compounds can be classified into rod-shaped types (rod-shaped liquid crystal compounds) and disc-shaped types (discotic liquid crystal compounds) based on their shape. Furthermore, liquid crystal compounds can be classified into low-molecular-weight types and high-molecular-weight types. High-molecular-weight compounds generally refer to those with a degree of polymerization of 100 or more (Polymer Physics and Phase Transition Dynamics, by Masao Doi, p. 2, Iwanami Shoten, 1992). In this invention, any type of liquid crystal compound can be used, but it is preferable to use a rod-shaped liquid crystal compound or a discotic liquid crystal compound, and more preferably a rod-shaped liquid crystal compound. Two or more rod-shaped liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of rod-shaped liquid crystal compounds and discotic liquid crystal compounds may be used. As the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Publication No. 11-513019 or paragraphs 0026 to 0098 of Japanese Patent Application Publication No. 2005-289980 can be preferably used. As discotic liquid crystal compounds, for example, those described in paragraphs 0020 to 0067 of Japanese Patent Publication No. 2007-108732 and paragraphs 0013 to 0108 of Japanese Patent Publication No. 2010-244038 can be preferably used.

[0056] The type of polymerizable group in the liquid crystal compound is not particularly limited, but functional groups capable of addition polymerization are preferred, polymerizable ethylenically unsaturated groups or cyclic polymerizable groups are more preferred, and (meth)acryloyl groups, vinyl groups, styryl groups, or allyl groups are even more preferred.

[0057] Furthermore, the optically anisotropic layer produced by this invention is a layer formed by fixing a polymerizable liquid crystal compound (a rod-shaped liquid crystal compound or a discotic liquid crystal compound having polymerizable groups) by polymerization or the like, and once it is formed as a layer, it no longer needs to exhibit liquid crystal properties.

[0058] The content of the liquid crystal compound in the composition layer is not particularly limited, but it is preferably 60% by mass or more, and more preferably 70% by mass or more, relative to the total mass of the composition layer, as this makes it easier to control the orientation state of the liquid crystal compound. There is no particular upper limit, but it is preferably 99% by mass or less, and more preferably 97% by mass or less.

[0059] (Other ingredients) The composition layer may contain other components besides the chiral agent and liquid crystal compound mentioned above. For example, the composition layer may contain a polymerization initiator. When the composition layer contains a polymerization initiator, polymerization of the liquid crystal compound having polymerizable groups proceeds more efficiently. Examples of polymerization initiators include known polymerization initiators, such as photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred. In particular, polymerization initiators that are sensitive to light irradiated in step 5A, described later, are preferred.

[0060] Preferably, the polymerization initiator has a molar extinction coefficient that is maximum among the wavelengths of light irradiated in step 3A, which is 0.1 times or less than the molar extinction coefficient that is maximum among the wavelengths of light irradiated in step 5A. Furthermore, the molar extinction coefficient at the wavelength of light irradiation in step 3A of the polymerization initiator is preferably 5000 L / (mol·cm) or less, more preferably 4000 L / (mol·cm) or less, and even more preferably 3000 L / (mol·cm) or less, in order to facilitate the formation of a predetermined optical anisotropy layer. The lower limit is not particularly limited, and 0 L / (mol·cm) is preferred, but it is often 30 L / (mol·cm) or more. The content of polymerization initiator in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, relative to the total mass of the composition layer.

[0061] The composition layer may contain a photosensitizer. The type of photosensitizer is not particularly limited, and known photosensitizers can be used. Furthermore, the molar extinction coefficient at the wavelength of light irradiation in step 3A of the photosensitizer is preferably 5000 L / (mol·cm) or less, more preferably 4800 L / (mol·cm) or less, and even more preferably 4500 L / (mol·cm) or less, in order to facilitate the formation of a predetermined optical anisotropy layer. The lower limit is not particularly limited, and 0 L / (mol·cm) is preferred, but it is often 30 L / (mol·cm) or more. The content of the photosensitizer in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, relative to the total mass of the composition layer.

[0062] The composition layer may contain polymerizable monomers different from the liquid crystal compound having polymerizable groups. Examples of polymerizable monomers include radical polymerizable compounds and cationic polymerizable compounds, with polyfunctional radical polymerizable monomers being preferred. Examples of polymerizable monomers include those described in paragraphs 0018 to 0020 of Japanese Patent Application Publication No. 2002-296423. The content of polymerizable monomers in the composition layer is not particularly limited, but is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass, relative to the total mass of the liquid crystal compound.

[0063] The composition layer may contain a leveling agent. The leveling agent is not particularly limited, but fluorine-based leveling agents or silicon-based leveling agents are preferred, and fluorine-based leveling agents are more preferred, as they facilitate the formation of the leveling agent distribution described later. Fluorine-based leveling agents are leveling agents having a fluorine atom, and preferably having a fluoroaliphatic group. The fluorine-based leveling agent preferably has repeating units represented by formula (1).

[0064] [ka]

[0065] In formula (1), R 1represents a hydrogen atom, a halogen atom, or a methyl group. L 1 represents a single bond or a divalent linking group. The divalent linking group is not particularly limited, and examples thereof include a divalent hydrocarbon group (for example, a divalent aliphatic hydrocarbon group such as an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 1 to 10 carbon atoms, and an alkynylene group having 1 to 10 carbon atoms, and a divalent aromatic hydrocarbon group such as an arylene group), a divalent heterocyclic group, -O-, -S-, -NH-, -CO-, or a group combining these (for example, -CO-O-, -O-divalent hydrocarbon group-, -(O-divalent hydrocarbon group) m -O- (m represents an integer of 1 or more), and -O-CO-divalent hydrocarbon group- etc.). n represents an integer of 1 to 18, preferably an integer of 4 to 12, and more preferably an integer of 6 to 8. X is a hydrogen atom or a fluorine atom.

[0066] As the repeating unit represented by the formula (1), the repeating unit represented by the formula (2) is preferable in terms of easily forming the distribution of the leveling agent described later.

[0067]

Chemical formula

[0068] In the formula (2), the definitions of R 1 , n and X are the same as the definitions of the respective groups in the above formula (1). Y represents an oxygen atom, a sulfur atom or -N(R 2 )-. R 2 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent. m represents an integer of 1 to 6, preferably an integer of 1 to 3.

[0069] The fluorine-based leveling agent may have only one kind of the repeating unit represented by the formula (1), or may have two or more kinds.

[0070] The content of the repeating units represented by formula (1) in the fluorine-based leveling agent is not particularly limited, but is preferably 20 to 100% by mass, and more preferably 30 to 95% by mass, relative to the total repeating units of the fluorine-based leveling agent, in that it facilitates the formation of the leveling agent distribution described later. When the fluorine-based leveling agent has two or more repeating units represented by formula (1), it is preferable that the total content thereof is within the above range.

[0071] The fluorine-based leveling agent may have repeating units other than those represented by formula (1). Other repeating units may include, for example, repeating units having hydrophilic groups (e.g., poly(oxyalkylene) groups, hydroxyl groups, etc.).

[0072] The fluorine-based leveling agent may have repeating units represented by formula (3).

[0073] [ka]

[0074] R 3 This represents a hydrogen atom, a halogen atom, or a methyl group. L 2 This represents a single bond or a divalent linking group. The definition of a divalent linking group is as described above. L 3 The symbol represents an alkylene group. The alkylene group preferably has 2 to 3 carbon atoms. p represents an integer between 4 and 20, preferably between 5 and 15. R 4 represents a hydrogen atom or substituent. Examples of substituents include alkyl groups, alkoxy groups, halogen atoms, aryl groups, cyano groups, hydroxyl groups, amino groups, or combinations thereof (e.g., -alkylene groups -OH).

[0075] The fluorine-based leveling agent may have only one repeating unit represented by formula (3), or it may have two or more repeating units.

[0076] The content of the repeating units represented by formula (3) in the fluorine-based leveling agent is not particularly limited, but is preferably 2 to 70% by mass, and more preferably 5 to 60% by mass, relative to the total repeating units of the fluorine-based leveling agent, in that it facilitates the formation of the leveling agent distribution described later. When the fluorine-based leveling agent has two or more repeating units represented by formula (3), it is preferable that the total content thereof is within the above range.

[0077] The weight-average molecular weight of the fluorine-based leveling agent is not particularly limited, but it is preferably 3000 to 30000, and more preferably 5000 to 25000, as this facilitates the formation of the leveling agent distribution described later.

[0078] As a silicon-based leveling agent, a leveling agent containing multiple dialkylsilyloxy units as repeating units is preferred.

[0079] The content of the leveling agent in the optically anisotropic layer is not particularly limited, but is preferably 0.010 to 5.000% by mass, and more preferably 0.020 to 2.000% by mass, relative to the total mass of the optically anisotropic layer.

[0080] The composition layer may contain a polymer. Examples of polymers include cellulose esters. Examples of cellulose esters include those described in paragraph 0178 of Japanese Patent Application Publication No. 2000-155216. The polymer content in the composition layer is not particularly limited, but is preferably 0.1 to 10% by mass, and more preferably 0.1 to 8% by mass, relative to the total mass of the liquid crystal compound.

[0081] In addition to the above, the composition layer may also contain additives (orientation control agents) that promote horizontal or vertical orientation in order to bring the liquid crystal compound into a horizontal or vertical orientation state.

[0082] (substrate) As will be described later, when forming the composition layer, it is preferable to form the composition layer on a substrate. The substrate is a plate that supports the composition layer. A transparent substrate is preferred as the substrate. A transparent substrate is defined as a substrate with a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0083] The retardation value in the thickness direction of the substrate at a wavelength of 550 nm (Rth(550)) is not particularly limited, but -110 to 110 nm is preferred, and -80 to 80 nm is more preferred. The in-plane retardation value (Re(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably 0 to 50 nm, more preferably 0 to 30 nm, and even more preferably 0 to 10 nm.

[0084] As the material for forming the substrate, a polymer with excellent optical performance, transparency, mechanical strength, thermal stability, moisture shielding properties, and isotropy is preferred. Examples of polymer films that can be used as substrates include cellulose acylate films (e.g., cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth)acrylonitrile films, and films of polymers having an alicyclic structure (norbornene-based resins (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefins (Zeonex: trade name, manufactured by Nippon Zeon Corporation))). Among these, triacetylcellulose, polyethylene terephthalate, or polymers having an alicyclic structure are preferred as materials for the polymer film, with triacetylcellulose being more preferred.

[0085] The substrate may contain various additives (e.g., optical anisotropy modifiers, wavelength dispersion modifiers, fine particles, plasticizers, UV inhibitors, degradation inhibitors, release agents, etc.).

[0086] The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm. The substrate may also consist of multiple laminated layers. To improve adhesion with the layer placed on top of it, the surface of the substrate may be subjected to surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment). Alternatively, an adhesive layer (primer layer) may be provided on the substrate. Furthermore, to provide slipperiness during the transport process and to prevent the back and front surfaces from sticking together after winding, a polymer layer containing inorganic particles with an average particle size of approximately 10 to 100 nm mixed in a solid content mass ratio of 5 to 40% may be placed on one side of the substrate.

[0087] The substrate may be a so-called temporary support. In other words, after carrying out the manufacturing method of the present invention, the substrate may be peeled off from the optically anisotropic layer.

[0088] Alternatively, a rubbing treatment may be applied directly to the surface of the substrate. In other words, a substrate that has already undergone a rubbing treatment may be used. The direction of the rubbing treatment is not particularly limited, and the optimal direction can be appropriately selected depending on the direction in which the liquid crystal compound is to be oriented. The rubbing process can be applied to a processing method widely used as a liquid crystal alignment process for LCDs (liquid crystal displays). Specifically, a method can be used in which the surface of the substrate is rubbed in a certain direction using paper, gauze, felt, rubber, nylon fibers, or polyester fibers to obtain alignment.

[0089] An alignment film may be placed on the substrate. The oriented film can be formed by means such as rubbing of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or accumulation of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) by the Langmuir-Bludget method (LB film). Furthermore, orientation films are known in which orientation functions are generated by the application of an electric field, a magnetic field, or light irradiation (preferably polarized light). The orientation film is preferably formed by a polymer rubbing treatment.

[0090] Examples of polymers included in the orientation film include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, and polycarbonate, as described in paragraph 0022 of Japanese Patent Publication No. 8-338913. Silane coupling agents can also be used as polymers. Among these, water-soluble polymers (e.g., poly(N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol, or modified polyvinyl alcohol are more preferred, and polyvinyl alcohol or modified polyvinyl alcohol are even more preferred.

[0091] As described above, the orientation film can be formed by applying a solution containing the polymer, which is the orientation film forming material, and an optional additive (e.g., a crosslinking agent) onto a substrate, then heating and drying (crosslinking), and finally rubbing it.

[0092] (Step 1A procedure) In step 1A, a composition layer containing the above-mentioned components is formed, but the procedure is not particularly limited. For example, this could be a method of coating a substrate with the composition containing the above-mentioned chiral agent and liquid crystal compound having polymerizable groups, and drying it as needed (hereinafter also simply referred to as the "coating method"), or a method of forming a separate composition layer and transferring it to the substrate. Among these, the coating method is preferred from the viewpoint of productivity. The application method will be described in detail below.

[0093] The composition used in the coating method includes the chiral agent mentioned above, a liquid crystal compound having a polymerizable group, and other components used as needed (e.g., polymerization initiators, polymerizable monomers, surfactants, and polymers). The content of each component in the composition is preferably adjusted to match the content of each component in the composition layer described above.

[0094] The coating method is not particularly limited and includes, for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, a drying process may be performed on the coating film applied to the substrate after the composition has been applied. By performing the drying process, the solvent can be removed from the coating film.

[0095] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0096] <Process 2A> Step 2A is a process of applying heat treatment to the composition layer to orient the liquid crystal compounds in the composition layer. By performing this step, the liquid crystal compounds in the composition layer will be in a predetermined orientation state. The optimal heat treatment conditions are selected according to the liquid crystal compound used. In particular, the most common heating temperatures are 25-250°C, with 40-150°C being more frequent, and 50-130°C being even more common. The heating time is often between 0.1 and 60 minutes, with 0.2 to 5 minutes being more common.

[0097] The orientation state of the liquid crystal compound obtained by step 2A changes depending on the helical induced force of the chiral agent described above. To form an optically anisotropic layer having, along the thickness direction, a layer in which the orientation state of a liquid crystal compound is fixed in a torsion orientation along a helical axis extending along the thickness direction, and a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed, the absolute value of the weighted average helical induced force of the chiral agent in the composition layer formed by step 1A is 0.0 to 1.9 μm. -1 Preferably, the size is 0.0 to 1.5 μm. -1 It is more preferable that the size be 0.0 to 1.0 μm. -1 It is even more preferable that the size be 0.0 to 0.5 μm. -1 It is particularly preferable that the size be 0.0 to 0.02 μm. -1 It is especially preferable that it be zero, and zero is most preferable.

[0098] The weighted average helical induced force of chiral agents is the sum of the values ​​obtained by dividing the product of the helical induced force of each chiral agent contained in the composition layer and the concentration (mass%) of each chiral agent in the composition layer by the total concentration (mass%) of the chiral agents in the composition layer, when a composition contains two or more chiral agents. For example, when two types of chiral agents (chiral agent X and chiral agent Y) are used in combination, it is expressed by the following formula (B). Equation (B) Weighted average helical induced force (μm -1 ) = (Helical induced force of chiral agent X (μm) -1 ) × Concentration of chiral agent X in the composition layer (mass%) + helical induced force of chiral agent Y (μm -1 ) × Concentration of chiral agent Y in the composition layer (mass%) / (Concentration of chiral agent X in the composition layer (mass%) + Concentration of chiral agent Y in the composition layer (mass%)) However, in equation (B) above, if the helical direction of the chiral agent is right-handed, the helical induced force is a positive value. If the helical direction of the chiral agent is left-handed, the helical induced force is a negative value. That is, for example, if the helical induced force is 10 μm -1 In the case of the chiral agent, when the helical direction of the helix induced by the above chiral agent is right-handed, the helical induction force is 10 μm -1 This is expressed as follows. On the other hand, when the helical direction of the helix induced by the above chiral agent is left-handed, the helical induction force is -10 μm -1 It is expressed as follows.

[0099] If the absolute value of the weighted average helical induced force of the chiral agent in the composition layer formed by step 1A is 0, then a composition layer 202 in which the liquid crystal compound LC is homogeneously oriented is formed on the substrate 18, as shown in Figure 6. Figure 6 is a cross-sectional view of the substrate 18 and the composition layer 202. In the composition layer 202 shown in Figure 6, chiral agent A and chiral agent B are present at the same concentration, the helical direction induced by chiral agent A is left-handed, and the helical direction induced by chiral agent B is right-handed. Furthermore, the absolute value of the helical induced force of chiral agent A and the absolute value of the helical induced force of chiral agent B are assumed to be the same.

[0100] <Process 3A> Step 3A, following Step 2A, involves irradiating the composition layer with light for 50 seconds or less at an oxygen concentration of 1 volume% or higher, at a rate of 300 mJ / cm². 2 The process is as follows. The mechanism of this process will be explained below using drawings. In the following explanation, an example of performing process 3A on the composition layer 202 shown in Figure 6 will be used as a representative example. As shown in Figure 6, in step 3A, light irradiation is performed from the direction opposite to the composition layer 202 side of the substrate 18 (the direction of the white arrow in Figure 6) under conditions of an oxygen concentration of 1 volume% or more. Although light irradiation is performed from the substrate 18 side in Figure 6, it may also be performed from the composition layer 202 side. In this case, comparing the lower region 202A on the substrate 18 side of the composition layer 202 with the upper region 202B on the opposite side of the substrate 18, the surface of the upper region 202B is on the air side, so the oxygen concentration in the upper region 202B is higher and the oxygen concentration in the lower region 202A is lower. Therefore, when the composition layer 202 is irradiated with light, polymerization of the liquid crystal compound proceeds easily in the lower region 202A, and the orientation state of the liquid crystal compound is fixed. In addition, chiral agent A is also present in the lower region 202A, and chiral agent A is also photosensitive, causing a change in helical induced force. However, since the orientation state of the liquid crystal compound is fixed in the lower region 202A, even if step 4A, which involves heat treatment of the light-irradiated composition layer as described later, is performed, no change in the orientation state of the liquid crystal compound occurs. Furthermore, because the oxygen concentration is high in the upper region 202B, even when light is irradiated, the polymerization of the liquid crystal compound is inhibited by oxygen, making polymerization difficult to proceed. In addition, since chiral agent A is also present in the upper region 202B, chiral agent A becomes photosensitive, and the helical induced force changes. Therefore, when step 4A, described later, is performed, the orientation state of the liquid crystal compound changes in accordance with the changed helical induced force. In other words, by performing step 3A, the orientation state of the liquid crystal compound is more easily fixed in the substrate-side region (lower region) of the composition layer. On the other hand, in the region of the composition layer opposite the substrate side (upper region), the orientation state of the liquid crystal compound is less likely to be fixed, and the helical induced force changes depending on the photosensitive chiral agent A.

[0101] Step 3A is carried out under conditions of an oxygen concentration of 1 volume% or higher. In particular, an oxygen concentration of 2 volume% or higher is preferred, and 5 volume% or higher is more preferred, as it facilitates the formation of layers with different orientation states of the liquid crystal compounds within the optically anisotropic layer. There is no particular upper limit, but 100 volume% is an example.

[0102] The light irradiation time in step 3A is 50 seconds or less, preferably 30 seconds or less, and more preferably 10 seconds or less, from the viewpoint of ease of forming the predetermined optical anisotropy layer and productivity. There is no particular lower limit, but from the viewpoint of curing the liquid crystal compound, it is preferably 0.1 seconds or more, and more preferably 0.2 seconds or more. The irradiation dose in step 3A is 300 mJ / cm². 2 The following is the reason why 250 mJ / cm² is chosen, considering the ease with which a predetermined optical anisotropy layer can be formed and the productivity. 2 The following is preferable: 200 mJ / cm² 2 The following are more preferable. The lower limit is not particularly limited, but from the viewpoint of curing the liquid crystal compound, 1 mJ / cm² is preferable. 2 The above is preferable, 5 mJ / cm 2 The above is preferable. In addition, the light irradiation in step 3A of the first embodiment is preferably carried out at 15 to 70°C (preferably 25 to 50°C).

[0103] The light used for irradiation can be any light that the chiral agent A is sensitive to. In other words, the light used for irradiation is not particularly limited as long as it is an active light or radiation that alters the helical induced force of the chiral agent A. Examples include the emission spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light, X-rays, ultraviolet light, and electron beams. Of these, ultraviolet light is preferred.

[0104] <Process 4A> Step 4A is a step in which the composition layer is heat-treated at a higher temperature than that used during light irradiation, after step 3A. By performing this step, the orientation state of the liquid crystal compound changes in the region where the helical induced force of chiral agent A in the light-irradiated composition layer has changed. More specifically, this step is a step in which the composition layer after step 3A is heat-treated at a higher temperature than that used during irradiation to orient the liquid crystal compound in the composition layer that was not fixed in step 3A. The mechanism of this process will be explained below using diagrams.

[0105] As described above, when step 3A is performed on the composition layer 202 shown in Figure 6, the orientation state of the liquid crystal compound is fixed in the lower region 202A, whereas polymerization of the liquid crystal compound does not proceed easily in the upper region 202B, and the orientation state of the liquid crystal compound is not fixed. Furthermore, the helical induced force of chiral agent A changes in the upper region 202B. When such a change in the helical induced force of chiral agent A occurs, the force twisting the liquid crystal compound in the upper region 202B changes compared to the state before light irradiation. This point will be explained in more detail. As described above, the composition layer 202 shown in Figure 6 contains chiral agent A and chiral agent B at the same concentration. The helical direction induced by chiral agent A is left-handed, and the helical direction induced by chiral agent B is right-handed. Furthermore, the absolute value of the helical induced force of chiral agent A is the same as the absolute value of the helical induced force of chiral agent B. Therefore, the weighted average helical induced force of the chiral agents in the composition layer before light irradiation is 0. The above embodiment is shown in Figure 8. In Figure 8, the vertical axis represents the helical induced force of the chiral agent (μm). -1 This represents "(μm) × concentration of chiral agent (mass%)", and the further this value is from zero, the greater the helical induced force. First, the relationship between chiral agent A and chiral agent B in the composition layer before light irradiation corresponds to the time when the amount of light irradiation is 0, and "the helical induced force of chiral agent A (μm) -1 The absolute value of "( ) × concentration of chiral agent A (mass %)" and "helical induced force of chiral agent B (μm)" -1 This corresponds to a state where the absolute value of "(A) × concentration of chiral agent B (mass%)" is equal. In other words, the helical-inducing forces of chiral agent A, which induces left-handedness, and chiral agent B, which induces right-handedness, cancel each other out. In the upper region 202B under these conditions, if light irradiation is performed and the helical induction force of chiral agent A decreases with the amount of light irradiation, as shown in Figure 8, then, as shown in Figure 9, the weighted average helical induction force of the chiral agent in the upper region 202B increases, and the right-handed helical induction force becomes stronger. In other words, the helical induction force that induces the helix in the liquid crystal compound increases in the direction of the helix induced by chiral agent B (+) as the irradiation amount increases. Therefore, when the composition layer 202 after step 3A, in which such a change in weighted average helical induced force has occurred, is subjected to heat treatment to promote the reorientation of the liquid crystal compound, as shown in Figure 7, in the upper region 202B, the liquid crystal compound LC becomes twisted and oriented along the helical axis extending in the thickness direction of the composition layer 202. On the other hand, as described above, in the lower region 202A of the composition layer 202, polymerization of the liquid crystal compound proceeds during step 3A and the orientation state of the liquid crystal compound is fixed, so reorientation of the liquid crystal compound does not proceed. As described above, by performing step 4A, two regions with different orientation states of the liquid crystal compound are formed along the thickness direction of the composition layer.

[0106] In addition, while Figures 6 and 7 above describe an embodiment in which a chiral agent A whose helical-inducing force decreases upon light irradiation is used, the embodiment is not limited to this. For example, a chiral agent A whose helical-inducing force increases upon light irradiation may be used as the chiral agent A. In that case, the helical-inducing force induced by the chiral agent A increases upon light irradiation, and the liquid crystal compound becomes twisted and oriented in the direction of rotation induced by the chiral agent A. Furthermore, while Figures 6 and 7 above illustrate an embodiment in which chiral agent A and chiral agent B are used in combination, the embodiment is not limited to this. For example, an embodiment using two types of chiral agent A may also be used. Specifically, an embodiment using a chiral agent A1 that induces left-handedness and a chiral agent A2 that induces right-handedness may be used in combination. Chiral agents A1 and A2 may each be independently chiral agents that increase the helical induced force or chiral agents that decrease the helical induced force. For example, a chiral agent that induces left-handedness and whose helical induced force increases upon light irradiation may be used in combination with a chiral agent that induces right-handedness and whose helical induced force decreases upon light irradiation.

[0107] The heat treatment is carried out at a higher temperature than that used during light irradiation. The difference between the heat treatment temperature and the temperature during light irradiation is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0108] The heat treatment temperature is preferably higher than the temperature during light irradiation and is the temperature at which the unfixed liquid crystal compounds in the composition layer are aligned. More specifically, it is often 35 to 250°C, more often 50 to 150°C, even more often between 50°C and 150°C, and particularly often between 60 and 130°C. The heating time is often between 0.01 and 60 minutes, with 0.03 to 5 minutes being more common.

[0109] Furthermore, while there are no particular restrictions on the absolute value of the weighted average helical induced force of the chiral agent in the composition layer after light irradiation, the absolute value of the difference between the weighted average helical induced force of the chiral agent in the composition layer after light irradiation and the weighted average helical induced force before light irradiation is 0.05 μm. -1 The above is preferable, with a range of 0.05 to 10.0 μm. -1 More preferably, 0.1 to 10.0 μm -1 That is even more preferable.

[0110] <Process 5A> Step 5A is a process in which the composition layer is cured after step 4A to form an optically anisotropic layer. By performing this step, the orientation state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed.

[0111] The curing method is not particularly limited and includes photocuring and heat curing. Among these, photocuring is preferred, and ultraviolet irradiation is more preferred. For ultraviolet irradiation, light sources such as ultraviolet lamps are used. There are no specific restrictions on the amount of light (e.g., ultraviolet light) exposure, but generally, it is between 100 and 800 mJ / cm². 2 A certain degree is desirable. The atmosphere during light irradiation is not particularly limited; light irradiation may be carried out in air or in an inert atmosphere. In particular, it is preferable that light irradiation be carried out at an oxygen concentration of less than 1 volume%.

[0112] When photocuring is performed as a curing treatment, the temperature conditions during photocuring are not particularly limited, and any temperature that maintains the orientation of the liquid crystal compound in step 4A is acceptable. The difference between the temperature of the heat treatment in step 4A and the temperature during the photocuring treatment is preferably within 100°C, and more preferably within 80°C. Furthermore, it is preferable that the temperature of the heat treatment in step 4A and the temperature during the photocuring treatment are the same, or that the temperature during the photocuring treatment is lower.

[0113] In the optically anisotropic layer obtained by the hardening treatment, the orientation state of the liquid crystal compound is fixed.

[0114] <<Second Embodiment>> In a second embodiment of the optically anisotropic layer, the first and second layers are layers in which the orientation state of a liquid crystal compound twisted along a helical axis extending in the thickness direction is fixed, and the twist angle of the liquid crystal compound in the first layer is different from the twist angle of the liquid crystal compound in the second layer. Figure 10 shows an example of a second embodiment of the optically anisotropic layer. The optically anisotropic layer 300 shown in Figure 10 is an optically anisotropic layer formed using a liquid crystal compound LC, and has a first layer 300A and a second layer 300B along the thickness direction. Both the first layer 300A and the second layer 300B are layers in which the orientation state of the liquid crystal compound, which is twisted along a helical axis extending along the thickness direction, is fixed. The twist angle of the liquid crystal compound in the first layer 300A is different from the twist angle of the liquid crystal compound in the second layer 300B. The orientation of the liquid crystal compound in the first layer 300A and the second layer 300B may be left-handed (counterclockwise) or right-handed (clockwise) twist.

[0115] The optical properties of the first and second layers in the second embodiment of the optical anisotropy layer are not particularly limited, but when the thickness of the first layer is d1 and the refractive index anisotropy of the first layer measured at a wavelength of 550 nm is Δn1, it is preferable that the first layer satisfies the following equation (1B-1) in order to suitably apply the optical anisotropy layer to a circular polarizer. Formula (1B-1) 205nm≦Δn1d1≦345nm In particular, it is more preferable that equation (1B-2) is satisfied, and even more preferable that equation (1B-3) is satisfied. Formula (1B-2) 225nm≦Δn1d1≦325nm Formula (1B-3) 245nm≦Δn1d1≦305nm

[0116] In the second embodiment, when the thickness of the second layer is d2 and the refractive index anisotropy of the second layer measured at a wavelength of 550 nm is Δn2, it is preferable that the second layer satisfies the following equation (2B-1) in such a way that the optical anisotropy layer can be suitably applied to a circular polarizing plate. Formula (2B-1) 70nm≦Δn2d2≦210nm In particular, it is more preferable that equation (2B-2) is satisfied, and even more preferable that equation (2B-3) is satisfied. Formula (2B-2) 90nm≦Δn2d2≦190nm Formula (2B-3) 110nm≦Δn2d2≦170nm

[0117] The absolute value of the torsion angle of the liquid crystal compound in the first layer is not particularly limited, but it is preferably greater than 0° and less than or equal to 60°, and more preferably between 10° and 50°, in order to suitably apply the optically anisotropic layer to a circular polarizer.

[0118] The absolute value of the torsion angle of the liquid crystal compound in the second layer is not particularly limited, but 50 to 110° is preferred, and 60 to 100° is more preferred, in that the optically anisotropic layer can be suitably applied to a circular polarizing plate.

[0119] The optical properties of the first and second layers in the second embodiment of the optical anisotropy layer are not particularly limited, but it is preferable that the optical properties of the first and second optical anisotropy layers (relationship between the torsion angle, Δn1d1, Δn2d2, and slow axis of the liquid crystal compound) described in claim 1 or 5 of Japanese Patent No. 5753922 are satisfied.

[0120] In the second embodiment of the optically anisotropic layer, it is preferable to exhibit inverse wavelength dispersion. In other words, it is preferable that the in-plane retardation Re(450) measured at a wavelength of 450 nm of the optical anisotropy layer, Re(550) measured at a wavelength of 550 nm of the optical anisotropy layer, and Re(650) measured at a wavelength of 650 nm of the optical anisotropy layer satisfy the relationship Re(450) ≤ Re(550) ≤ Re(650).

[0121] The method for manufacturing the second embodiment of the optical anisotropy layer is not particularly limited, but the absolute value of the weighted average helical induced force of the chiral agent in the composition layer formed by step 1A described above is increased (for example, 0 μm). -1 One possible method is to perform the process in a way that surpasses the standard. When the absolute value of the weighted average helical induced force of the chiral agent in the composition layer formed by step 1A is large, first, as shown in Figure 11, the liquid crystal compound is twisted in orientation along a helical axis extending in the thickness direction in the composition layer 302 on the substrate 18 on which step 2A has been performed. When steps 3A and 4A described above are performed on such a composition layer, the twisted orientation of the liquid crystal compound remains fixed in the region of the composition layer with a low oxygen concentration (lower region 302A in Figure 12), while the helical induced force changes in the region of the composition layer with a high oxygen concentration (upper region 302B in Figure 12), and after performing step 5A, it is possible to form layers with different twist angles of the liquid crystal compound.

[0122] <<Third Embodiment>> In a third embodiment of the optical anisotropic layer, the first and second layers are optical anisotropic layers in which a cholesteric liquid crystal phase is fixed, wherein the helical pitch of the cholesteric liquid crystal phase in the first layer is different from the helical pitch of the cholesteric liquid crystal phase in the second layer. Figure 13 shows an example of a third embodiment of the optically anisotropic layer. The optical anisotropic layer 400 shown in Figure 13 is an optical anisotropic layer formed by fixing a cholesteric liquid crystal phase using a liquid crystal compound LC, and has a first layer 400A and a second layer 400B along the thickness direction. The helical pitch of the cholesteric liquid crystal phase is different in the first layer 400A and the second layer 400B, with the helical pitch of the second layer 400B being larger than that of the first layer 400A. Therefore, the selective reflection center wavelength originating from the cholesteric liquid crystal phase of the first layer 400A is different from the selective reflection center wavelength originating from the cholesteric liquid crystal phase of the second layer 400B. For example, the optical anisotropic layer may be an optical anisotropic layer having a layer in which a cholesteric liquid crystal phase that reflects blue light is fixed along the thickness direction and a layer in which a cholesteric liquid crystal phase that reflects green light is fixed, or it may be an optical anisotropic layer having a layer in which a cholesteric liquid crystal phase that reflects green light is fixed along the thickness direction and a layer in which a cholesteric liquid crystal phase that reflects red light is fixed. In the optically anisotropic layer, it is preferable to have at least two layers selected from the group consisting of a layer in which a cholesteric liquid crystal phase that reflects blue light is fixed, a layer in which a cholesteric liquid crystal phase that reflects green light is fixed, and a layer in which a cholesteric liquid crystal phase that reflects red light is fixed.

[0123] In this specification, the selective reflection center wavelength is defined as the minimum value of transmittance in the object (component) in question, T min When expressed as (%), the half-maximum transmittance is represented by the following formula: T 1 / 2 (%) refers to the average value of two wavelengths. Formula for calculating half-maximum transmittance: T 1 / 2 =100-(100-T min )÷2 Furthermore, within the visible light spectrum, light with wavelengths between 420 nm and less than 500 nm is blue light (B light), light with wavelengths between 500 nm and less than 600 nm is green light (G light), and light with wavelengths between 600 nm and less than 700 nm is red light (R light).

[0124] The first layer 400A and the second layer 400B contained in the optical anisotropic layer 400 exhibit selective circular polarization reflection, selectively reflecting circularly polarized light of either right-circularly polarized or left-circularly polarized light, while transmitting circularly polarized light of the other sense. The selective reflection center wavelength λ of the cholesteric liquid crystal phase depends on the pitch P of the helical structure in the cholesteric liquid crystal phase (=period of the helix), and follows the relationship λ = n × P with respect to the average refractive index n of the cholesteric liquid crystal phase. As can be seen from this equation, the selective reflection center wavelength can be adjusted to a predetermined range by adjusting the values ​​of n and P. In this specification, the term "sense" may also be used to refer to the twist direction of the helix of the cholesteric liquid crystal phase. When the twist direction (sense) of the helix of the cholesteric liquid crystal phase is to the right, it reflects right-circularly polarized light and transmits left-circularly polarized light. When the sense is to the left, it reflects left-circularly polarized light and transmits right-circularly polarized light. Furthermore, it is preferable that the sense of the cholesteric liquid crystal phase in layers with different helical pitches within the optically anisotropic layer be the same.

[0125] The helical pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used with the liquid crystal compound, or its concentration; therefore, the desired helical pitch can be obtained by adjusting these factors. For methods of measuring the helical sense and pitch, the methods described in "Introduction to Liquid Crystal Chemistry Experiments," edited by the Japanese Liquid Crystal Society, Sigma Publishing, 2007, p. 46, and "Liquid Crystal Handbook," edited by the Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196, can be used.

[0126] The method for manufacturing the third embodiment of the optical anisotropy layer is not particularly limited, but a manufacturing method having the following steps 1B to 5B is preferred. Step 1B: A step to form a composition layer containing a chiral agent that includes at least a photosensitive chiral agent whose helical induced force changes upon light irradiation, and a liquid crystal compound having polymerizable groups. Step 2B: A step in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds in the composition layer and form a cholesteric liquid crystal phase. Step 3B: After Step 2B, under conditions of an oxygen concentration of 1 volume% or more, the composition layer is irradiated with light for 50 seconds or less and at a concentration of 300 mJ / cm². 2 The following steps Step 4B: After step 3B, the composition layer is subjected to heat treatment at a higher temperature than that during light irradiation. Step 5B: After Step 4B, the composition layer is subjected to a curing treatment to form an optically anisotropic layer. As will be described later, in the third embodiment, in order to produce an optically anisotropic layer with the above characteristics, it is preferable that the total content of chiral agents in the composition layer (total content of all chiral agents) is greater than 5.0% by mass of the total mass of the liquid crystal compound. The main difference between the first embodiment and the third embodiment is the content of the chiral agent. The following details the procedures for each of the above steps.

[0127] <Process 1B> Step 1B is a step of forming a composition layer containing a chiral agent that includes at least a photosensitive chiral agent whose helical induced force changes upon light irradiation, and a liquid crystal compound having polymerizable groups. By performing this step, a composition layer that will be subjected to the light irradiation treatment described later is formed. The chiral agents (chiral agent A and chiral agent B) and liquid crystal compounds contained in the composition layer are as described in step 1A. Furthermore, the composition layer may contain other components besides the chiral agent and the liquid crystal compound, as described in step 1A above.

[0128] In step 1B, a chiral agent is included in the composition layer such that a cholesteric liquid crystal phase is formed in step 2B, which will be described later. In the second embodiment, the total content of chiral agents in the composition layer (total content of all chiral agents) is not particularly limited, but in terms of ease of controlling the orientation state of the liquid crystal compound, it is preferably more than 5.0% by mass, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, relative to the total mass of the liquid crystal compound. There is no particular upper limit, but it is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0129] The content of chiral agent A in the chiral agent is not particularly limited, but it is preferably 5 to 95% by mass and more preferably 10 to 90% by mass relative to the total mass of the chiral agent, as this makes it easier to control the orientation state of the liquid crystal compound.

[0130] The absolute value of the helical-inducing force of the chiral agent in the composition layer formed by step 1B is 10 μm -1 The above is preferable, and 15 μm -1 The above is more preferable, 20 μm -1 The above is even more preferable. There is no particular upper limit, but 250 μm -1 The following is often the case, 200 μm -1 The following are common cases. Furthermore, if the composition contains two or more chiral agents, it is preferable that the absolute value of the weighted mean helical induced force of the chiral agents in the composition layer formed by step 1B is within the above range. The definition of weighted mean spiral-induced force is as described above.

[0131] The method for forming the composition layer in step 1B is the same as the method for forming the composition layer in step 1A described above.

[0132] <Process 2B> Step 2B is a process in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds in the composition layer and form a cholesteric liquid crystal phase. By performing this step, the liquid crystal compounds in the composition layer are in a predetermined orientation state. The optimal heat treatment conditions are selected according to the liquid crystal compound used. In particular, the most common heating temperatures are 25-250°C, with 40-150°C being more frequent, and 50-130°C being even more common. The heating time is often between 0.1 and 60 minutes, with 0.2 to 5 minutes being more common.

[0133] <Process 3B> Step 3B, following Step 2B, involves irradiating the composition layer with light for 50 seconds or less and at a concentration of 300 mJ / cm² under conditions of an oxygen concentration of 1 volume% or higher. 2 The process is as follows. The mechanism of this process will be explained below using diagrams. As shown in Figure 14, in step 3B, light irradiation is performed from the direction opposite to the composition layer 402 side of the substrate 18 (the direction of the white arrow in Figure 14) under conditions of an oxygen concentration of 1 volume% or more. Although light irradiation is performed from the substrate 18 side in Figure 14, it may also be performed from the composition layer 402 side. In this case, comparing the lower region 402A on the substrate 18 side of the composition layer 402 with the upper region 402B on the opposite side of the substrate 18, the surface of the upper region 402B is on the air side, so the oxygen concentration in the upper region 402B is high, and the oxygen concentration in the lower region 402A is low. Therefore, when the composition layer 402 is irradiated with light, polymerization of the liquid crystal compound proceeds easily in the lower region 402A, and the orientation state of the liquid crystal compound is fixed. In addition, chiral agent A is also present in the lower region 402A, and chiral agent A is also photosensitive, causing a change in helical induced force. However, since the orientation state of the liquid crystal compound is fixed in the lower region 402A, even if step 4B, in which the light-irradiated composition layer is subjected to heat treatment as described later, no change in the orientation state of the liquid crystal compound occurs. Furthermore, because the oxygen concentration is high in the upper region 402B, even when light is irradiated, the polymerization of the liquid crystal compound is inhibited by oxygen, making polymerization difficult to proceed. In addition, since chiral agent A is also present in the upper region 402B, chiral agent A becomes photosensitive, and the helical induced force changes. Therefore, when step 4B, described later, is performed, the orientation state of the liquid crystal compound changes in accordance with the changed helical induced force. In other words, by performing step 3B, the orientation of the liquid crystal compound is more easily fixed in the substrate-side region (lower region) of the composition layer. On the other hand, in the region of the composition layer opposite the substrate side (upper region), the orientation of the liquid crystal compound is less likely to be fixed, and the helical induced force changes depending on the photosensitive chiral agent A.

[0134] The various conditions for light irradiation in step 3B (oxygen concentration, irradiation time, irradiation dose, etc.) are the same as the various conditions for light irradiation in step 3A described above.

[0135] <Process 4B> Step 4B is a step in which the composition layer is heat-treated at a higher temperature than that used during light irradiation, after step 3B. By performing this step, the orientation state of the liquid crystal compound changes in the region where the helical induced force of chiral agent A in the light-irradiated composition layer has changed. More specifically, this step is a step in which the composition layer after step 3B is heat-treated at a higher temperature than that used during irradiation to orient the liquid crystal compound in the composition layer that was not fixed in step 3B. The mechanism of this process will be explained below using diagrams.

[0136] As described above, when step 3B is performed on the composition layer 402 shown in Figure 14, the orientation state of the liquid crystal compound is fixed in the lower region 402A, whereas polymerization of the liquid crystal compound does not proceed easily in the upper region 402B, and the orientation state of the liquid crystal compound is not fixed. Furthermore, the helical induced force of chiral agent A changes in the upper region 402B. When such a change in the helical induced force of chiral agent A occurs, the force twisting the liquid crystal compound in the upper region 402B changes compared to the state before light irradiation. This point will be explained in more detail. In the following explanation, we will describe in detail the case where the composition layer 402 contains a chiral agent A whose induced helical direction is left-handed and whose helical induction force decreases upon light irradiation. In the upper region 402B under these conditions, if light irradiation is performed and the helical induced force of chiral agent A decreases with the amount of light irradiation, as shown in Figure 16, the helical induced force of the chiral agent in the upper region 402B will decrease. Therefore, when the composition layer 402 after step 3B, where such a change in helical induced force has occurred, is subjected to heat treatment to promote the reorientation of the liquid crystal compound, the helical pitch of the cholesteric liquid crystal phase increases in the upper region 402B, as shown in Figure 15. On the other hand, as described above, in the lower region 402A of the composition layer 402, polymerization of the liquid crystal compound proceeds during step 3B and the orientation state of the liquid crystal compound is fixed, so reorientation of the liquid crystal compound does not proceed. As described above, by carrying out step 4B, multiple cholesteric liquid crystal phases with different helical pitches are formed along the thickness direction of the composition layer.

[0137] In addition, while Figures 14 and 15 above describe an embodiment in which chiral agent A is a chiral agent whose helical induced force decreases upon light irradiation, the embodiment is not limited to this. For example, chiral agent A may be a chiral agent whose helical induced force increases upon light irradiation. Furthermore, while Figures 14 and 15 above describe an embodiment using a chiral agent A whose induced helical direction is left-handed, the embodiment is not limited to this. For example, a chiral agent A whose induced helical direction is right-handed may also be used. Furthermore, although Figures 14 and 15 above describe an embodiment in which only one type of chiral agent A is used, the embodiment is not limited to this. For example, an embodiment in which two types of chiral agent A are used may be used, or an embodiment in which chiral agent A and chiral agent B are used in combination may be used.

[0138] The heat treatment is carried out at a higher temperature than that used during light irradiation. The difference between the heat treatment temperature and the temperature during light irradiation is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0139] The temperature of the heat treatment is preferably higher than the temperature during light irradiation and is a temperature for aligning the un-fixed liquid crystal compounds in the composition layer. More specifically, it is often in the range of 40 to 250 °C, more often in the range of 50 to 150 °C, even more often above 50 °C and below 150 °C, and particularly often in the range of 60 to 130 °C. The heating time is often in the range of 0.01 to 60 minutes, and more often in the range of 0.03 to 5 minutes.

[0140] Also, the absolute value of the helical induction force of the chiral agent in the composition layer after light irradiation is not particularly limited, but the absolute value of the difference between the helical induction force of the chiral agent in the composition layer after light irradiation and the helical induction force before light irradiation is 0.05 μm -1 or more is preferable, 0.05 to 10.0 μm -1 is more preferable, 0.1 to 10.0 μm -1 is even more preferable. In addition, when two or more chiral agents are contained in the composition, the absolute value of the difference between the weighted average helical induction force of the chiral agent in the composition layer after light irradiation and the weighted average helical induction force before light irradiation is 0.05 μm -1 or more is preferable, 0.05 to 10.0 μm -1 is more preferable, 0.1 to 10.0 μm -1 is even more preferable.

[0141] <Step 5B> Step 5B is a step of performing a curing treatment on the composition layer after Step 4B to form an optically anisotropic layer. By carrying out this step, the alignment state of the liquid crystal compounds in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed. Note that by carrying out this step, an optically anisotropic layer formed by fixing a cholesteric liquid crystal phase and having a plurality of layers with different helical pitches of the cholesteric liquid crystal phase along the thickness direction is formed. The length of the helical pitch in each formed layer is often constant. That is, by carrying out this step, an optically anisotropic layer formed by fixing a cholesteric liquid crystal phase and having two layers with different helical pitches of the cholesteric liquid crystal phase along the thickness direction and with a constant helical pitch in each layer can be formed.

[0142] Examples of the curing method in Step 5B include the curing method in Step 5A.

[0143] <<Fourth Embodiment>> In the fourth embodiment of the optically anisotropic layer, the first layer and the second layer are optically anisotropic layers formed by fixing the alignment state of the liquid crystal compound, and the inclination angle of the alignment direction of the liquid crystal compound with respect to the layer surface in the first layer is different from the inclination angle of the alignment direction of the liquid crystal compound with respect to the layer surface in the second layer. FIG. 17 shows an example of the fourth embodiment of the optically anisotropic layer. The optically anisotropic layer 500 shown in FIG. 17 is an optically anisotropic layer formed by fixing the alignment state of the liquid crystal compound LC, and has a first layer 500A and a second layer 500B along the thickness direction. The first layer 500A is a layer formed by fixing the alignment state of the homogeneously aligned (horizontally aligned) liquid crystal compound, and the second layer 500B is a layer formed by fixing the alignment state of the homeotropically aligned (vertically aligned) liquid crystal compound.

[0144] As used herein, homeotropic alignment refers to a state (optical uniaxiality) in which the molecular axes of the liquid crystal compound (for example, the long axis in the case of a rod-shaped liquid crystal compound) are perpendicular to the layer surface and arranged in the same orientation. Here, perpendicular does not require being strictly perpendicular, and means an alignment in which the inclination angle formed by the average molecular axis of the liquid crystal compound in the layer and the normal line of the layer surface is less than 20 degrees. Also, the same orientation does not require being strictly the same orientation, and means that when the orientation of the molecular axis of the liquid crystal compound is measured at any 20 positions, the maximum difference (the difference between the orientations of the molecular axes of the two liquid crystal compounds with the largest difference among the orientations of the molecular axes of the 20 liquid crystal compounds) among the orientations of the molecular axes of the liquid crystal compound at the 20 positions is less than 10°.

[0145] When the thickness of the first layer 500A is d1 and the in-plane refractive index anisotropy of the first layer 500A measured at a wavelength of 550 nm is Δn1, it is preferable that the first layer satisfies the following equation (1C-1) in order to suitably apply the optical anisotropy layer to a circular polarizer. Formula (1C-1) 100nm≦Δn1d1≦180nm In particular, it is more preferable that the conditions satisfy equation (1C-2). Formula (1C-2) 110nm≦Δn1d1≦170nm

[0146] Furthermore, when the thickness of the second layer 500B is d2 and the in-plane refractive index anisotropy of the second layer 500B measured at a wavelength of 550 nm is Δn2, it is preferable that the second layer 500B satisfies the following equation (2C-1) in order to suitably apply the optical anisotropy layer to a circular polarizer. Formula (2C-1) 0nm≦Δn2d2≦30nm In particular, it is more preferable that the equation (2C-2) is satisfied. Formula (2C-2) 0nm≦Δn2d2≦20nm The retardation in the thickness direction of the second layer 500B at a wavelength of 550 nm is preferably -150 to -20 nm, and more preferably -120 to -20 nm.

[0147] In the fourth embodiment of the optically anisotropic layer, it is preferable to exhibit inverse wavelength dispersion. In other words, it is preferable that the in-plane retardation Re(450) measured at a wavelength of 450 nm of the optical anisotropy layer, Re(550) measured at a wavelength of 550 nm of the optical anisotropy layer, and Re(650) measured at a wavelength of 650 nm of the optical anisotropy layer satisfy the relationship Re(450) ≤ Re(550) ≤ Re(650).

[0148] The optical properties of the fourth embodiment of the optical anisotropy layer are not particularly limited, but it is preferable that it functions as a λ / 4 plate. A λ / 4 plate is a plate that has the function of converting linearly polarized light of a specific wavelength to circularly polarized light (or circularly polarized light to linearly polarized light), and is a plate (optical anisotropic layer) in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ)=λ / 4. This equation only needs to be achieved at any wavelength in the visible light range (for example, 550 nm), but it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship 110 nm ≤ Re(550) ≤ 180 nm.

[0149] In the above embodiment, an optically anisotropic layer having a layer in which the orientation state of a homeotropically oriented liquid crystal compound is fixed along the thickness direction and a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed has been described in detail. However, the embodiment is not limited to this, as long as the optically anisotropic layer includes two layers with different inclination angles of the orientation direction of the liquid crystal compound with respect to the layer surface. For example, the optically anisotropic layer may be an optically anisotropic layer having a layer in which the orientation state of a tilted liquid crystal compound is fixed and a layer in which the orientation state of a homogeneous liquid crystal compound is fixed.

[0150] The method for manufacturing the fourth embodiment of the optical anisotropy layer is not particularly limited, but a manufacturing method having the following steps 1C to 5C is preferred. Step 1C: A step to form a composition layer containing a photosensitive compound whose polarity changes upon light irradiation, and a liquid crystal compound having polymerizable groups. Step 2C: A step in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds in the composition layer. Step 3C: After Step 2C, under conditions of an oxygen concentration of 1 volume% or more, the composition layer is irradiated with light for 50 seconds or less and at a concentration of 300 mJ / cm². 2 The following steps Step 4C: After step 3C, the composition layer is subjected to heat treatment at a higher temperature than that during light irradiation. Step 5C: After Step 4C, the composition layer is subjected to a curing treatment to form an optically anisotropic layer. In the fourth embodiment, as will be described later, a photosensitive compound whose polarity changes upon light irradiation is used. The following details the procedures for each of the above steps.

[0151] <Process 1C> Step 1C is a step in which a composition layer is formed containing a photosensitive compound whose polarity changes upon light irradiation and a liquid crystal compound having polymerizable groups. By performing this step, a composition layer is formed that will be subjected to the light irradiation treatment described later. The liquid crystal compound contained in the composition layer is as described in step 1A. Furthermore, the composition layer may contain other components as described in step 1A above.

[0152] (Photosensitive compounds whose polarity changes upon exposure to light) The composition layer of step 1C contains a photosensitive compound whose polarity changes upon light irradiation (hereinafter also referred to as "specific photosensitive compound"). A photosensitive compound whose polarity changes upon light irradiation is a compound whose polarity changes before and after light irradiation. As described later, when a composition layer containing such a specific photosensitive compound is subjected to light irradiation in step 1C, the polarity of the specific compound changes in the air-side region of the composition layer, and when step 4C is performed, the orientation direction of the liquid crystal compound becomes inclined or perpendicular to the layer surface in accordance with the change in polarity.

[0153] The change in polarity of the specific photosensitive compound may be either a change to hydrophilicity or a change to hydrophobicity. Among these, a change to hydrophilicity is preferred because it allows for the easy formation of an orientation state in which the orientation direction of the liquid crystal compound is tilted or perpendicular to the layer surface. As a specific photosensitive compound that becomes hydrophilic upon light irradiation, a compound having a group that generates a hydrophilic group upon light irradiation is preferred. The type of hydrophilic group is not particularly limited and may be a cationic group, anionic group, or nonionic group. More specifically, examples include carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, and hydroxyl groups.

[0154] The specific photosensitive compound preferably has a fluorine atom or a silicon atom. When the specific photosensitive compound has the above atoms, the specific photosensitive compound tends to be unevenly distributed near the surface of the composition layer, and a desired optically anisotropic layer is easily formed.

[0155] As the specific photosensitive compound, a compound represented by formula (X) is preferred.

[0156] [Chemical formula]

[0157] In the above formula (X), T represents an aromatic hydrocarbon group having a valence of n + m, Sp represents a single bond or a divalent linking group, Hb represents a fluorine-substituted alkyl group having 4 to 30 carbon atoms, m represents an integer of 1 to 4, n represents an integer of 1 to 4, A represents a group represented by the following formula (Y),

[0158] [Chemical formula]

[0159] In the above formula (Y), R1 to R5 each independently represent a hydrogen atom or a monovalent substituent, * represents a bonding site. In the above formula (X), when there are a plurality of the above Sp, Hb, or A, the plurality of Sp, the plurality of Hb, or the plurality of A may be the same or different from each other.

[0160] In the above formula (X), T represents an aromatic hydrocarbon group having a valence of n + m. The above aromatic hydrocarbon group is not particularly limited as long as it is a group obtained by removing n+m hydrogen atoms from an aromatic hydrocarbon ring, but it is preferably a group with 6 to 22 carbon atoms, more preferably a group with 6 to 14 carbon atoms, and even more preferably a group with 6 to 10 carbon atoms. The aromatic hydrocarbon group is particularly preferably a benzene ring. The above aromatic hydrocarbon group may have further substituents in addition to the group represented by -Sp-Hb and the group represented by -C(=O)OA. Examples of substituents include alkyl groups (e.g., alkyl groups having 1 to 8 carbon atoms), alkoxy groups (e.g., alkoxy groups having 1 to 8 carbon atoms), halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms), cyano groups, and acyloxy groups (e.g., acetoxy groups).

[0161] In the above formula (X), Sp represents a single bond or a divalent linking group, and is preferably a divalent linking group. The above-mentioned divalent linking group is not particularly limited, but it is preferably a linking group selected from the group consisting of a linear or branched alkylene group (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms), a linear or branched alkenylene group (preferably having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 6 carbon atoms), a linear or branched alkynylene group (preferably having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 6 carbon atoms), or a group in which one or more of these are substituted with the "divalent organic group" shown below. Among the divalent linking groups mentioned above, alkylene groups having 1 to 10 carbon atoms, in which one or more -CH2- groups are substituted with the "divalent organic groups" shown below, are preferred, from the viewpoint of further improving solubility. (Divalent organic group) Examples of the above divalent organic groups include -O-, -S-, -C(=O)-, -C(=O)O-, -OC(=O)-, -C(=O)S-, -SC(=O)-, -NR6C(=O)-, or -C(=O)NR6-. Among these, -O-, -S-, -C(=O)-, -C(=O)O-, -OC(=O)-, -C(=O)S-, or SC(=O)- are more preferred in terms of further hydrophilization, -O-, -C(=O)-, -C(=O)O-, or OC(=O)- are even more preferred, and -O-, -C(=O)O-, or OC(=O)- are particularly preferred. Furthermore, R6 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Furthermore, if the above-mentioned divalent linking group contains the above-mentioned divalent organic group, it is preferable that the divalent organic groups are not adjacent to each other.

[0162] In the above formula (X), Hb represents a fluorine-substituted alkyl group having 4 to 30 carbon atoms. Hb preferably has 4 to 20 carbon atoms, and more preferably 4 to 10 carbon atoms. Here, the fluorine-substituted alkyl group may be a perfluoroalkyl group in which all hydrogen atoms are replaced with fluorine atoms, or a fluoroalkyl group in which some of the hydrogen atoms are replaced with fluorine atoms. Furthermore, the fluorine-substituted alkyl group may be linear, branched, or cyclic, but linear or branched is preferred, and linear is more preferred. Among the fluorine-substituted alkyl groups, a perfluoroalkyl group structure is preferred.

[0163] In the above formula (X), preferred embodiments of the group represented by -Sp-Hb are exemplified below. In the following examples, * indicates the connection point with T. (C p F 2p+1 )-(CH2) q -O-(CH2) r -O-* (C p F 2p+1 )-(CH2) q -C(=O)O-(CH2) r-C(=O)O-* (C p F 2p+1 )-(CH2) q -OC(=O)-(CH2) r -C(=O)O-* (C p F 2p+1 )-(CH2) q -OC(=O)-(CH2) r -OC(=O)-* In the group represented by -Sp-Hb above, p is preferably 4 to 30, more preferably 4 to 20, and even more preferably 4 to 10. q is preferably 0 to 6, more preferably 0 to 4, and even more preferably 0 to 3. r is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3. Furthermore, it is preferable that the total number of carbon atoms in the parts other than the perfluoro group be 10 or less.

[0164] In equation (X) above, n and m each independently represent integers from 1 to 4. From the standpoint of further hydrophilization, n is preferably 2 or greater. m is preferably 1 to 3, and more preferably 2.

[0165] In the above formula (X), A represents the group represented by the above formula (Y). The following explains equation (Y).

[0166] In the above formula (Y), R1 to R5 each independently represent a hydrogen atom or a monovalent substituent. The monovalent substituents represented by R1 to R5 are not particularly limited.

[0167] Examples of monovalent substituents represented by R1~R4 include halogen atoms (e.g., fluorine, chlorine, bromine, and iodine atoms), hydroxyl groups, cyano groups, and substituted or unsubstituted amino groups (-N(R A ) is represented by 2, and two R Aeach independently represents a hydrogen atom or a monovalent organic group (examples of the monovalent organic group include an alkyl group having 1 to 5 carbon atoms).), an alkoxy group having 1 to 8 carbon atoms (for example, a methoxy group or an ethoxy group), an amide group having 2 to 8 carbon atoms (for example, -N(R B )C(=O)R C (R B represents a hydrogen atom or a monovalent organic group (examples of the monovalent organic group include an alkyl group having 1 to 5 carbon atoms), and R C represents a monovalent organic group (examples of the monovalent organic group include an alkyl group having 1 to 5 carbon atoms).), or -C(=O)N(R D )2 (the two R D each independently represents a hydrogen atom or a monovalent organic group (for example, an alkyl group having 1 to 5 carbon atoms).)), an alkoxycarbonyl group having 2 to 8 carbon atoms (for example, -C(=O)OCH3), an acyloxy group having 2 to 8 carbon atoms (for example, -OC(=O)CH3), and -Sp A -Hb A are exemplified.

[0168] The above Sp A , and the above Hb A are synonymous with Sp and Hb in the above formula (X), respectively, and their preferred embodiments are also the same. In the formula (Y), when a plurality of R1 to R4 represent -Sp A -Hb A , the plurality of existing Sp A may be the same or different from each other, and the plurality of existing Hb A may be the same or different from each other.

[0169] Among them, as the above R^{1} to R^{4}, each independently, a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an alkoxy group, -NH_{2}, -NH(CH_{3}), -N(CH_{3})_{2}, -C(=O)OCH_{3}, -OC(=O)CH_{3}, -NHC(=O)CH_{3}, -N(CH_{3})C(=O)CH_{3}, or -Sp A -Hb A is preferable. In particular, from the viewpoint of accelerating the decomposition rate of the compound represented by formula (X) by exposure and further promoting hydrophilicity and / or enhancing the orientation, R1 to R4 are each independently -OCH3 or Sp A -Hb<000009�>is more preferable. When it is -OCH3, since it contains ether oxygen in its structure (particularly, the position bonded to the benzene ring in formula (Y) is ether oxygen), the decomposition rate of the compound represented by formula (X) by exposure tends to increase more rapidly, and hydrophilicity tends to further progress. On the other hand, when it is -Sp A -Hb A the orientation tends to be enhanced more by the presence of Hb A . In addition, when Sp A contains ether oxygen in its structure (particularly, when ether oxygen is contained at the terminal on the side opposite to the side bonded to Hb A in Sp A (in other words, the terminal on the side linked to the benzene ring of formula (Y))), an effect of increasing the decomposition rate can be obtained similar to the above -OCH3.

[0170] ]>Furthermore, from the viewpoint of accelerating even more the decomposition rate of the compound represented by formula (X) by exposure and further promoting hydrophilicity, at least two of R1 to R4 are each independently preferably -OCH3 or Sp B -Hb B and it is more preferable that R2 and R3 are each independently -OCH3 or Sp B -Hb B . Here, Sp B represents an alkylene group having 1 to 10 carbon atoms in which -CH2- is replaced by -O-. Among them, as described above, Hb B in Sp BWhen an ether oxygen is present at the end opposite to the side that bonds with (in other words, the end that connects to the benzene ring in formula (Y)), the effect of accelerating the decomposition rate becomes more pronounced, and hydrophilization progresses further. Furthermore, when the -CH2- in the alkylene group is replaced by multiple -O-, it is preferable that the -O- groups are not adjacent to each other. The alkylene group is more preferably having 1 to 7 carbon atoms, even more preferably having 1 to 6 carbon atoms, and particularly preferably having 1 to 4 carbon atoms. The alkylene group may be either linear or branched, but it is preferable that it be linear.

[0171] The above Hb B This represents a fluorine-substituted alkyl group with 4 to 30 carbon atoms. (See above Hb) B The preferred embodiment is the same as that of Hb in formula (X) described above. Note that in equation (Y), multiple of R1 to R4 are -Sp B -Hb B When representing multiple Sp B Hb B The individuals may be the same or different.

[0172] In particular, in order to further accelerate the decomposition rate of the compound represented by formula (X) by exposure, promote hydrophilization, and further enhance orientation, at least two of the above R1 to R4 are -Sp B -Hb B Preferably, both R2 and R3 are -Sp B -Hb B It is more preferable that the above-Sp B -Hb B A structure represented by the following formula (Z) is preferred. Formula (Z) (C p F 2p+1 )-(CH2) q -O-(CH2) r -O-* In formula (Z), p is preferably 4 to 30, more preferably 4 to 20, and even more preferably 4 to 10. q is preferably 0 to 5, more preferably 0 to 4, and even more preferably 0 to 3. r is preferably 1 to 5, more preferably 1 to 4, and even more preferably 1 to 3.

[0173] In the above formula (Y), R5 is preferably a hydrogen atom, a methyl group, an ethyl group, or an aromatic group. The aromatic group is not particularly limited, but it is preferably one with 6 to 14 carbon atoms, more preferably one with 6 to 10 carbon atoms, and even more preferably a phenyl group. Among the above R5s, a methyl group, an ethyl group, or an aromatic group is preferred, an ethyl group or an aromatic group is more preferred, and an aromatic group is even more preferred, as these groups accelerate the decomposition rate of the compound represented by formula (X) by exposure and promote further hydrophilicity.

[0174] Furthermore, in equation (Y) above, * represents the bonding site with C(=O)O- in equation (X) above.

[0175] The compound represented by formula (X) above may or may not have a symmetrical molecular structure. Here, symmetry refers to point symmetry, line symmetry, or rotational symmetry, while asymmetry refers to a structure that does not fall under any of these categories.

[0176] Furthermore, in the compound represented by the above formula (X), if there are multiple instances of Sp, Hb, or A, the multiple instances of Sp, Hb, or A may be the same or different from each other.

[0177] The content of the specific photosensitive compound in the composition layer can be appropriately set depending on the characteristics of the optically anisotropic layer to be formed (e.g., retardation and wavelength dispersion). In particular, the content of the specific photosensitive compound is preferably 0.01 to 10% by mass, and more preferably 0.05 to 5% by mass, relative to the total mass of the liquid crystal compound, as this facilitates the formation of an optically anisotropic layer with a predetermined structure.

[0178] In step 1A, a composition layer containing the above-mentioned components is formed, but the procedure is not particularly limited. For example, this could be a method of coating a substrate with the composition containing the above-mentioned specific photosensitive compound and liquid crystal compound having polymerizable groups, and drying it as needed (hereinafter also simply referred to as the "coating method"), or a method of forming a separate composition layer and transferring it to the substrate. Among these, the coating method is preferred from the viewpoint of productivity. The application method will be described in detail below.

[0179] The composition used in the coating method includes the aforementioned specific photosensitive compound, a liquid crystal compound having a polymerizable group, and other components used as needed (e.g., polymerization initiators, polymerizable monomers, surfactants, and polymers). The content of each component in the composition is preferably adjusted to match the content of each component in the composition layer described above.

[0180] The coating method is not particularly limited and includes, for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, a drying process may be performed on the coating film applied to the substrate after the composition has been applied. By performing the drying process, the solvent can be removed from the coating film.

[0181] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0182] <Process 2C> Step 2C is a process in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds in the composition layer. By performing this step, the liquid crystal compounds in the composition layer reach a predetermined orientation. As shown in Figure 18, which will be described later, for example, by performing step 2C, the liquid crystal compounds in the composition become homogeneously oriented. The optimal heat treatment conditions are selected according to the liquid crystal compound used. In particular, the most common heating temperatures are 25-250°C, with 40-150°C being more frequent, and 50-130°C being even more common. The heating time is often between 0.1 and 60 minutes, with 0.2 to 5 minutes being more common.

[0183] <Process 3C> Step 3C, following Step 2C, involves irradiating the composition layer with light for 50 seconds or less and at a concentration of 300 mJ / cm² under conditions of an oxygen concentration of 1 volume% or higher. 2 The process is as follows. The mechanism of this process will be explained below using drawings. In the following explanation, the case in which the composition layer contains a compound that becomes hydrophilic upon light irradiation will be described as an example. In Figure 18, the liquid crystal compound LC is homogeneously oriented in the composition layer. As shown in Figure 18, in step 3C, light irradiation is performed from the direction opposite to the composition layer 502 side of the substrate 18 (the direction of the white arrow in Figure 18) under conditions of an oxygen concentration of 1 volume% or more. Although light irradiation is performed from the substrate 18 side in Figure 18, it may also be performed from the composition layer 502 side. In this case, comparing the lower region 502A on the substrate 18 side of the composition layer 502 with the upper region 502B on the opposite side of the substrate 18, the surface of the upper region 502B is on the air side, so the oxygen concentration in the upper region 502B is high, and the oxygen concentration in the lower region 502A is low. Therefore, when the composition layer 502 is irradiated with light, polymerization of the liquid crystal compound proceeds easily in the lower region 502A, and the orientation state of the liquid crystal compound is fixed. In addition, specific photosensitive compounds are also present in the lower region 502A, and these specific photosensitive compounds are also photosensitive, and hydrophilization proceeds. However, since the orientation state of the liquid crystal compound is fixed in the lower region 502A, even if step 4C, in which the light-irradiated composition layer is subjected to heat treatment as described later, no change occurs in the orientation state of the liquid crystal compound. Furthermore, because the oxygen concentration is high in the upper region 502B, even when light is irradiated, the polymerization of the liquid crystal compound is inhibited by oxygen, making polymerization difficult to proceed. In addition, since the specific photosensitive compound is also present in the upper region 502B, the specific photosensitive compound becomes photosensitive, and hydrophilization proceeds. Therefore, when step 4C, described later, is performed, the orientation state of the liquid crystal compound changes due to the influence of the changed polarity. In other words, by performing step 3C, the orientation state of the liquid crystal compound is more easily fixed in the substrate-side region (lower region) of the composition layer. On the other hand, in the region of the composition layer opposite the substrate side (upper region), the orientation state of the liquid crystal compound is less likely to be fixed, and the polarity changes depending on the specific photosensitive compound that is exposed to light.

[0184] The various conditions for light irradiation in process 3C (oxygen concentration, irradiation time, irradiation dose, etc.) are the same as the various conditions for light irradiation in process 3A described above.

[0185] <Process 4C> Step 4C is a process in which the composition layer is heat-treated at a higher temperature than that used during light irradiation, following step 3C. By performing this step, the orientation state of the liquid crystal compound changes in the region where the polarity has been changed by a specific photosensitive compound in the composition layer that has been light-irradiated. More specifically, this step is a process in which the composition layer after step 3C is heat-treated at a higher temperature than that used during irradiation to orient the liquid crystal compound in the composition layer that was not fixed in step 3C. The mechanism of this process will be explained below using diagrams.

[0186] As described above, when step 3C is performed on the composition layer 502 shown in Figure 18, the orientation state of the liquid crystal compound is fixed in the lower region 502A, whereas polymerization of the liquid crystal compound does not proceed easily in the upper region 502B, and the orientation state of the liquid crystal compound is not fixed. In addition, in the upper region 502B, the specific photosensitive compound is photosensitive and becomes hydrophilic. When such a change in polarity occurs, the orientation direction of the liquid crystal compound in the upper region 502B is affected compared to the state before light irradiation. This point will be explained in more detail below. As mentioned above, the following explanation will use the case in which the composition layer contains a specific photosensitive compound that becomes hydrophilic upon light irradiation as an example. If the composition layer contains a specific photosensitive compound that becomes hydrophilic upon light irradiation, then, as shown in Figure 19, when step 4C is performed, the liquid crystal compound will undergo homeotropic orientation in the upper region 502B. In particular, if the specific photosensitive compound is present near the surface of the composition layer, the liquid crystal compound is more likely to undergo homeotropic orientation. On the other hand, as described above, in the lower region 502A of the composition layer 502, polymerization of the liquid crystal compound proceeds during step 3C and the orientation state of the liquid crystal compound is fixed, so reorientation of the liquid crystal compound does not proceed. As described above, by performing step 4C, a region containing a liquid crystal compound whose orientation direction is inclined or perpendicular to the layer surface is formed.

[0187] Although Figure 19 above illustrates a configuration in which the liquid crystal compound is homeotropically oriented, the system is not limited to this configuration. For example, the liquid crystal compound may be in a tilted orientation.

[0188] The heat treatment is carried out at a higher temperature than that used during light irradiation. The difference between the heat treatment temperature and the temperature during light irradiation is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0189] The heat treatment temperature is preferably higher than the temperature during light irradiation and is the temperature at which the unfixed liquid crystal compounds in the composition layer are oriented. More specifically, it is often 40 to 250°C, more often 50 to 150°C, even more often between 50°C and 150°C, and particularly often between 60 and 130°C. The heating time is often between 0.01 and 60 minutes, with 0.03 to 5 minutes being more common.

[0190] <Process 5C> Step 5C is a step in which the composition layer is cured after step 4C to form an optically anisotropic layer. By performing this step, the orientation state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed. Furthermore, by performing this step, an optically anisotropic layer is formed having two layers along the thickness direction in which the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface is different. In particular, by performing this step, an optically anisotropic layer can be formed having a layer in which the orientation state of the homeotropically oriented or inclined-oriented liquid crystal compound is fixed along the thickness direction, and a layer in which the orientation state of the homogeneously oriented liquid crystal compound is fixed.

[0191] One method for the curing treatment in step 5C is the same as the curing treatment method in step 5A.

[0192] <<Fifth Embodiment>> In the fifth embodiment of the optically anisotropic layer, the first layer is a layer in which the orientation state of the liquid crystal compound is fixed, and the second layer is a layer in which the state in which the liquid crystal compound exhibits an isotropic phase is fixed. Figure 20 shows an example of a fifth embodiment of the optically anisotropic layer. The optically anisotropic layer 600 shown in Figure 20 is an optically anisotropic layer formed using a liquid crystal compound, and has a first layer 600A and a second layer 600B along the thickness direction. The first layer 600A is a layer in which the orientation state of the homogeneously oriented liquid crystal compound is fixed, and the second layer 600B is a layer in which the liquid crystal compound exhibits an isotropic phase state is fixed.

[0193] In Figure 20 above, an embodiment of an optically anisotropic layer having a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed along the thickness direction, and a layer in which the liquid crystal compound exhibits an isotropic phase is fixed. However, the embodiment is not limited to this, as long as it includes a layer in which the liquid crystal compound exhibits an isotropic phase. For example, an optically anisotropic layer may have a layer in which the orientation state of a homeotropically oriented liquid crystal compound is fixed along the thickness direction, and a layer in which the liquid crystal compound exhibits an isotropic phase. Alternatively, an optically anisotropic layer may have a layer in which a cholesteric liquid crystal phase formed using a liquid crystal compound is fixed along the thickness direction, and a layer in which the liquid crystal compound exhibits an isotropic phase. Furthermore, an optically anisotropic layer may have a layer in which the orientation state of a liquid crystal compound twisted along a helical axis extending along the thickness direction is fixed, and a layer in which the liquid crystal compound exhibits an isotropic phase is fixed.

[0194] The optical properties of the fifth embodiment of the optical anisotropy layer are not particularly limited, but it is preferable that it functions as a λ / 4 plate. A λ / 4 plate is a plate that has the function of converting linearly polarized light of a specific wavelength to circularly polarized light (or circularly polarized light to linearly polarized light), and is a plate (optical anisotropic layer) in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ)=λ / 4. This equation only needs to be achieved at any wavelength in the visible light range (for example, 550 nm), but it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship 110 nm ≤ Re(550) ≤ 180 nm.

[0195] The method for manufacturing the fifth embodiment of the optical anisotropy layer is not particularly limited, but a manufacturing method having the following steps 1D to 5D is preferred. Step 1D: Step to form a composition layer containing a liquid crystal compound having polymerizable groups. Step 2D: A step in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds in the composition layer. Step 3D: After Step 2D, the composition layer is irradiated with light for 50 seconds or less and at a concentration of 300 mJ / cm² under conditions of an oxygen concentration of 1 volume% or higher. 2 The following steps Step 4D: After step 3D, the composition layer is subjected to heat treatment at a temperature higher than that at the time of light irradiation and above the temperature at which the liquid crystal compound becomes isotropic. Step 5D: After Step 4D, the composition layer is subjected to a curing treatment to form an optically anisotropic layer. The following details the procedures for each of the above steps.

[0196] <Process 1D> Step 1D is a step of forming a composition layer containing a liquid crystal compound having polymerizable groups. By performing this step, a composition layer that will be subjected to the light irradiation treatment described later is formed. The liquid crystal compound contained in the composition layer is as described in step 1A. Furthermore, the composition layer may contain other components besides the liquid crystal compound, as described in step 1A above.

[0197] In step 1A, a composition layer containing the above-mentioned components is formed, but the procedure is not particularly limited. For example, this could be a method of coating a substrate with a composition containing the above-mentioned polymerizable liquid crystal compound and drying it as needed (hereinafter also simply referred to as the "coating method"), or a method of forming a separate composition layer and transferring it to the substrate. Among these, the coating method is preferred from the viewpoint of productivity. The application method will be described in detail below.

[0198] The composition used in the coating method includes the polymerizable liquid crystal compound described above, and other components used as needed (e.g., polymerization initiators, polymerizable monomers, surfactants, and polymers). The content of each component in the composition is preferably adjusted to match the content of each component in the composition layer described above.

[0199] The coating method is not particularly limited and includes, for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, a drying process may be performed on the coating film applied to the substrate after the composition has been applied. By performing the drying process, the solvent can be removed from the coating film.

[0200] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0201] <Process 2D> Step 2D is a process in which the composition layer is subjected to heat treatment to orient the liquid crystal compounds within the composition layer. By performing this step, the liquid crystal compounds in the composition layer reach a predetermined orientation. As shown in Figure 21, which will be described later, for example, by performing step 2D, the liquid crystal compounds in the composition become homogeneously oriented. The optimal heat treatment conditions are selected according to the liquid crystal compound used. In particular, the most common heating temperatures are 25-250°C, with 40-150°C being more frequent, and 50-130°C being even more common. The heating time is often between 0.1 and 60 minutes, with 0.2 to 5 minutes being more common.

[0202] <Process 3D> Step 3D, following Step 2D, involves irradiating the composition layer with light for 50 seconds or less at an oxygen concentration of 1 volume% or higher, at a rate of 300 mJ / cm². 2 The process is as follows. The mechanism of this process will be explained below using drawings. In Figure 21, the liquid crystal compound LC is homogeneously oriented in the composition layer. As shown in Figure 21, in step 3D, light irradiation is performed from the direction opposite to the composition layer 602 side of the substrate 18 (the direction of the white arrow in Figure 21) under conditions of an oxygen concentration of 1 volume% or more. Although light irradiation is performed from the substrate 18 side in Figure 21, it may also be performed from the composition layer 602 side. In this case, comparing the lower region 602A on the substrate 18 side of the composition layer 602 with the upper region 602B on the opposite side of the substrate 18, the surface of the upper region 602B is on the air side, so the oxygen concentration in the upper region 602B is high and the oxygen concentration in the lower region 602A is low. Therefore, when the composition layer 602 is irradiated with light, polymerization of the liquid crystal compound proceeds easily in the lower region 602A, and the orientation state of the liquid crystal compound is fixed. For this reason, even if step 4D, in which the light-irradiated composition layer is subjected to heat treatment as described later, no change in the orientation state of the liquid crystal compound occurs. Furthermore, because the oxygen concentration is high in the upper region 602B, even when light is irradiated, the polymerization of the liquid crystal compound is inhibited by oxygen, making polymerization difficult to proceed. Therefore, when step 4D, described later, is performed, the orientation state of the liquid crystal compound changes. In other words, by performing process 3D, the orientation state of the liquid crystal compound is more easily fixed in the substrate-side region (lower region) of the composition layer. On the other hand, in the region opposite the substrate-side of the composition layer (upper region), the orientation state of the liquid crystal compound is less likely to be fixed, and the orientation state of the liquid crystal compound changes due to process 4D, which will be described later.

[0203] The various conditions for light irradiation in process 3D (oxygen concentration, irradiation time, irradiation dose, etc.) are the same as the various conditions for light irradiation in process 3A described above.

[0204] <Process 4D> Step 4D is a process performed after step 3D in which the composition layer is heat-treated at a temperature higher than that at the time of light irradiation, and above the temperature at which the liquid crystal compound becomes isotropic. By performing this step, the liquid crystal compound exhibits an isotropic phase in the upper region of the composition layer where the orientation state of the liquid crystal compound is not fixed. The mechanism of this process will be explained below using diagrams.

[0205] As described above, when step 3D is performed on the composition layer 602 shown in Figure 21, the orientation state of the liquid crystal compound is fixed in the lower region 602A, whereas polymerization of the liquid crystal compound does not proceed easily in the upper region 602B, and the orientation state of the liquid crystal compound is not fixed. Therefore, when process 4D is performed, as shown in Figure 22, polymerization of the liquid crystal compound does not proceed in the upper region 602B, causing the orientation state of the liquid crystal compound to collapse and become an isotropic phase. On the other hand, as described above, in the lower region 602A of the composition layer 602, polymerization of the liquid crystal compound proceeds during step 3D and the orientation state of the liquid crystal compound is fixed, so reorientation of the liquid crystal compound does not proceed. As described above, by performing process 4D, an optically anisotropic layer is formed having a layer in which the orientation state of the liquid crystal compound (for example, a homogeneous orientation state) is fixed along the thickness direction, and a layer in which the liquid crystal compound is in an unoriented state (isotropic phase of the liquid crystal compound) is fixed.

[0206] The heat treatment is performed at a temperature higher than that used during light irradiation, and above the temperature at which the liquid crystal compound becomes isotropic. The difference between the heat treatment temperature and the temperature during light irradiation is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0207] The heat treatment temperature is preferably higher than the temperature during light irradiation and is the temperature at which the unfixed liquid crystal compound in the composition layer becomes an isotropic phase. More specifically, it is often 40 to 250°C, more often 50 to 150°C, even more often between 50°C and 150°C, and particularly often between 60 and 130°C. The heating time is often between 0.01 and 60 minutes, with 0.03 to 5 minutes being more common.

[0208] <Process 5D> Step 5D is a process in which the composition layer is cured after step 4D to form an optically anisotropic layer. By performing this step, the orientation state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed.

[0209] One method for the curing treatment in step 5D is the same as the curing treatment method in step 5A.

[0210] <<Application>> Optically anisotropic layers can be combined with various materials. For example, the optical anisotropic layer described above may be combined with other optical anisotropic layers. That is, as shown in Figure 23, a laminate 24 may be fabricated that includes a substrate 18, the optical anisotropic layer 10 described above, and other optical anisotropic layers 22. Although the laminate 24 shown in Figure 23 includes a substrate 18, the laminate does not necessarily have to include a substrate. Other optically anisotropic layers are not particularly limited and include, for example, A plates (positive A plates and negative A plates) and C plates (positive C plates and negative C plates). Among these, C plates are preferred because they are easy to apply to various applications described later (e.g., circular polarizers). The absolute range of the retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, but is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

[0211] In this specification, A plate and C plate are defined as follows: There are two types of A plates: positive A plates and negative A plates. When the refractive index in the slow axis direction (the direction in which the refractive index is maximum within the plane) is nx, the refractive index in the direction perpendicular to the slow axis within the plane is ny, and the refractive index in the thickness direction is nz, a positive A plate satisfies the relationship in equation (A1), and a negative A plate satisfies the relationship in equation (A2). Note that a positive A plate has a positive Rth value, and a negative A plate has a negative Rth value. Formula (A1) nx>ny≒nz Formula (A2) ny <nx≒nz The above "≒" includes not only cases where the two are completely identical, but also cases where they are substantially identical. "Substantially identical" means, for example, that (ny-nz)×d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, and that (nx-nz)×d is -10 to 10 nm, preferably -5 to 5 nm, and that that is also included in "nx≒nz". There are two types of C plates: positive C plates and negative C plates. Positive C plates satisfy the relationship in equation (C1), and negative C plates satisfy the relationship in equation (C2). Note that positive C plates show a negative value for Rth, and negative C plates show a positive value for Rth. Formula (C1) nz>nx≒ny Formula (C2) nz <nx≒ny Furthermore, the above "≒" includes not only cases where the two are completely identical, but also cases where they are substantially identical. "Substantially identical" means, for example, that (nx-ny)×d (where d is the thickness of the film) is between 0 and 10 nm, preferably between 0 and 5 nm, which is included in "nx≒ny".

[0212] The method for manufacturing the above-mentioned laminate is not particularly limited and known methods can be used. For example, one method is to laminate an optically anisotropic layer obtained by the manufacturing method of the present invention with another optically anisotropic layer (e.g., a C plate) to obtain a laminate. As for the lamination method, another optically anisotropic layer prepared separately may be bonded onto the optically anisotropic layer obtained by the manufacturing method of the present invention, or a composition for forming another optically anisotropic layer may be applied onto the optically anisotropic layer obtained by the manufacturing method of the present invention to form another optically anisotropic layer.

[0213] Furthermore, the optically anisotropic layer obtained by the manufacturing method of the present invention may be combined with a polarizer. That is, as shown in Figure 24, an optically anisotropic layer 28 with a polarizer may be manufactured, which includes a substrate 18, the optically anisotropic layer 10 described above, and a polarizer 26. In Figure 24, the polarizer 26 is placed on the substrate 18, but the invention is not limited to this embodiment, and the polarizer 26 may be placed on the optically anisotropic layer 10. Furthermore, although the polarized optical anisotropic layer 28 shown in Figure 24 includes the substrate 18, the polarized optical anisotropic layer does not necessarily have to include a substrate.

[0214] A polarizer can be any component that has the function of converting natural light into a specific linearly polarized light; for example, an absorptive polarizer can be used. There are no particular restrictions on the type of polarizer; commonly used polarizers can be used, such as iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based and dye-based polarizers are generally made by adsorbing iodine or a dichroic dye onto polyvinyl alcohol and then stretching it. A protective film may be placed on one or both sides of the polarizer.

[0215] The method for manufacturing the above-described optically anisotropic layer with a polarizer is not particularly limited and known methods can be used. For example, one method is to laminate the optically anisotropic layer obtained by the manufacturing method of the present invention with a polarizer to obtain an optically anisotropic layer with a polarizer.

[0216] Although the above describes an embodiment in which an optically anisotropic layer and a polarizer are laminated, in the present invention, a polarizer-equipped laminate may be manufactured by laminating the above-described laminate with a polarizer.

[0217] Optical anisotropic layers can be applied to a variety of uses. For example, optical anisotropic layers are suitably applied to circular polarizers, and the above-mentioned optical anisotropic layer with a polarizer can also be used as a circular polarizer. A circular polarizing plate having the above configuration is suitably used for anti-reflective applications in image display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and cathode ray tube displays (CRTs), and can improve the contrast ratio of the displayed light. For example, an embodiment in which the circular polarizer of the present invention is used on the light extraction surface side of an organic EL display device can be described. In this case, ambient light is linearly polarized by the polarizing film, and then becomes circularly polarized after passing through the optical anisotropy layer. When this is reflected by the metal electrode, the circular polarization state is reversed, and when it passes through the optical anisotropy layer again, it becomes linearly polarized with a 90° tilt from the incident state, and reaches the polarizing film where it is absorbed. As a result, the influence of ambient light can be suppressed.

[0218] In particular, the polarized optical anisotropic layer or polarized laminate described above is preferably applied to an organic EL display device. That is, the polarized optical anisotropic layer or polarized laminate is preferably placed on the organic EL panel of an organic EL display device and applied for anti-reflective purposes. An organic EL panel is a component in which a light-emitting layer or multiple organic compound thin films including a light-emitting layer are formed between a pair of electrodes, an anode and a cathode. In addition to the light-emitting layer, it may also have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and a protective layer, and each of these layers may have other functions. Various materials can be used to form each layer. [Examples]

[0219] The features of the present invention will be further described below with reference to examples and comparative examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted restrictively by the specific examples shown below.

[0220] <Example 1> (Fabrication of cellulose acylate film (substrate)) The following composition was placed in a mixing tank, stirred, and then heated at 90°C for 10 minutes. The resulting composition was then filtered through filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a dope. The solid content concentration of the dope was 23.5% by mass, the amount of plasticizer added was a ratio to the cellulose acylate, and the solvent of the dope was methylene chloride / methanol / butanol = 81 / 18 / 1 (by mass).

[0221] ------------------------------------------------------------------ Cellulose acylate dope ------------------------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.86, viscosity-average degree of polymerization 310) 100 parts by mass Sugar ester compound 1 (shown by chemical formula (S4)) 6.0 parts by mass Sugar ester compound 2 (shown by chemical formula (S5)) 2.0 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Solvents (methylene chloride / methanol / butanol) ------------------------------------------------------------------

[0222] [ka]

[0223] [ka]

[0224] The dope prepared as described above was cast using a drum film-forming machine. The dope for forming the core layer and the dope for forming the surface layer on the core layer were co-cast from the die so as to be in contact with a metal support cooled to 0°C, and then the resulting film was peeled off. The drum was made of SUS (Steel Use Stainless).

[0225] Using a tenter device that clips both ends of the film for transport, the film peeled from the drum was dried at 30-40°C for 20 minutes during transport. Next, the resulting film was further dried by zone heating while being transported on a roll. After that, the resulting film was knurled and then wound up. The obtained elongated cellulose acylate film had a thickness of 40 μm, with an in-plane retardation Re(550) of 1 nm and a thickness-direction retardation Rth(550) of 26 nm at a wavelength of 550 nm.

[0226] (Formation of optically anisotropic layer) The cellulose acylate film prepared as described above was subjected to a continuous rubbing process. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was 80°. If we consider the longitudinal direction of the film (transport direction) to be 90°, and observe from the cellulose acylate film side, with the width direction of the cellulose acylate film as the reference (0°) and the counterclockwise direction as a positive value, the rotation axis of the rubbing roller was 10°. In other words, the position of the rotation axis of the rubbing roller was rotated 80° clockwise relative to the longitudinal direction of the cellulose acylate film.

[0227] A composition (A) for forming an optically anisotropic layer, containing the rod-shaped liquid crystal compound described below, was applied to the rubbing-treated film using a Gieser coating machine to form a composition layer (corresponding to step 1A). The absolute value of the weighted average helical induced force of the chiral agent in the composition layer in step 1A was 0.0 μm -1 That was the case. Next, the resulting composition layer was heated at 100°C for 80 seconds (corresponding to step 2A). This heating caused the rod-shaped liquid crystal compounds in the composition layer to be oriented in a predetermined direction. Subsequently, under oxygen-containing air (oxygen concentration: approximately 20 vol%) at 40°C, ultraviolet light was irradiated onto the composition layer for 1 second using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) (corresponding to step 3A). At this time, the maximum irradiation dose within the plane was 13.2 mJ / cm². 2 The minimum value is 12.9 mJ / cm². 2 That was the case. Next, the resulting composition layer was heated at 90°C for 10 seconds (corresponding to step 4A). Subsequently, under a nitrogen atmosphere at 55°C, the composition layer was irradiated with ultraviolet light using a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 ), an optically anisotropic layer with a fixed orientation state of the liquid crystal compound was formed (corresponding to step 5A), and an optical film (A) was fabricated.

[0228] ------------------------------------------------------------------ Composition for forming an optically anisotropic layer (A) ------------------------------------------------------------------ • 80 parts by mass of the following rod-shaped liquid crystal compound (A) • 10 parts by mass of the following rod-shaped liquid crystal compound (B) • 10 parts by mass of the following rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.42 parts by mass of the following chiral agent (A) • 0.38 parts by mass of the following chiral agent (B) • 0.5 parts by mass of the following polymerizable polymer (X) • 0.08 parts by mass of the following polymer (A) • Methyl isobutyl ketone 117 parts by mass • Ethyl propionate 39 parts by mass ------------------------------------------------------------------

[0229] Rod-shaped liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

[0230] [ka]

[0231] Rod-shaped liquid crystal compound (B)

[0232] [ka]

[0233] Rod-shaped liquid crystal compound (C)

[0234] [ka]

[0235] Chiral agent (A)

[0236] [ka]

[0237] (Chiral agent B)

[0238] [ka]

[0239] Polymerizable polymer (X) (In the formula, the numerical value indicated for each repeating unit represents the content (mass %) of each repeating unit relative to the total number of repeating units.)

[0240] [ka]

[0241] Polymer (A) (In the formula, the numerical values ​​listed for each repeating unit represent the content (mass %) of each repeating unit relative to the total number of repeating units.)

[0242] [ka]

[0243] The optical film (A) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The optically anisotropic layer consisted of two layers exhibiting different optical anisotropy. The cellulose acylate film side layer (first layer) of the optically anisotropic layer was a layer in which a homogeneously oriented liquid crystal compound with a thickness (d1) of 1310 nm was fixed, and the air side layer (second layer) of the optically anisotropic layer was a layer in which a liquid crystal compound with a thickness (d2) of 1390 nm was fixed, which was twisted oriented with the thickness direction as the helical axis. Furthermore, the optical properties of the optical film (A) were determined using Axometrics' Axoscan and its analysis software (Multi-Layer Analysis). The product of Δn1 and thickness d1 at a wavelength of 550 nm in the first layer (Δn1d1) was 173 nm, the torsion angle of the liquid crystal compound was 0°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was -10° on the side in contact with the substrate and -10° on the side in contact with the second layer. Furthermore, the product of Δn2 and thickness d2 at a wavelength of 550 nm in the second layer (Δn2d2) was 184 nm, the twist angle of the liquid crystal compound was 75°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was -10° on the side in contact with the first layer and -85° on the air side. The orientation axis angle of the liquid crystal compound contained in the optical anisotropic layer is expressed by observing the substrate from the surface side of the optical anisotropic layer, with the longitudinal direction of the film as the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive. Furthermore, the torsional structure of the liquid crystal compound is represented here by observing the substrate from the surface side of the optically anisotropic layer, and using the orientation direction of the liquid crystal compound on the surface side (front side) as a reference, a clockwise (rightward) orientation of the liquid crystal compound on the substrate side (backward side) is represented as negative, and a counterclockwise (leftward) orientation is represented as positive.

[0244] (Fabrication of circular polarizing plates) A polyvinyl alcohol (PVA) film with a thickness of 80 μm was stained by immersion in an iodine aqueous solution with an iodine concentration of 0.05 mass% at 30°C for 60 seconds. Next, the obtained film was stretched longitudinally to five times its original length while immersed in a boric acid aqueous solution with a boric acid concentration of 4 mass% for 60 seconds, and then dried at 50°C for 4 minutes to obtain a polarizer with a thickness of 20 μm.

[0245] (Fabrication of polarizer protective film) A commercially available cellulose acylate film "TD80UL" (manufactured by Fujifilm Corporation) was prepared and immersed in a 1.5 mol / liter sodium hydroxide aqueous solution at 55°C, after which the sodium hydroxide was thoroughly rinsed off with water. Then, it was immersed in a 0.005 mol / liter dilute sulfuric acid aqueous solution at 35°C for 1 minute, and the dilute sulfuric acid solution was thoroughly rinsed off with water. Finally, the resulting film was thoroughly dried at 120°C to produce a polarizer protective film.

[0246] A polarizer protective film, also prepared as described above, was bonded to one side of the polarizer prepared as described above using a polyvinyl alcohol-based adhesive to create a laminate containing the polarizer and the polarizer protective film positioned on one side of the polarizer. An adhesive (SK-2057, manufactured by Soken Chemical Co., Ltd.) was applied to the polarizer side (without the polarizer protective film) of the laminate prepared as described above to form an adhesive layer, and the optical film (A) prepared as described above was bonded to the adhesive layer and the cellulose acylate film so that they were in close contact. The angle between the absorption axis of the polarizer and the in-plane slow axis of the polarizer side surface of the optical anisotropy layer in optical film (A) was 10°. Next, an adhesive was applied to the optical film (A) in the resulting laminate to form an adhesive layer. Following the procedure described above, a long circular polarizing plate (A) was fabricated in which a polarizer protective film, a polarizer, a cellulose acylate film, an optically anisotropic layer, and an adhesive layer were arranged in that order.

[0247] <Example 2> When irradiating with light from a 365nm LED lamp (manufactured by Acroedge Co., Ltd.), the output is adjusted to set the maximum irradiation dose within the plane to 13.3 mJ / cm². 2 The minimum value was 12.7 mJ / cm². 2 Except as otherwise provided, the optical film (B) and circular polarizer (B) were prepared using the same procedure as in Example 1.

[0248] <Example 3> (Formation of optically anisotropic layer) The cellulose acylate film prepared in Example 1 was subjected to continuous rubbing. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 90°.

[0249] A composition (B) for forming an optically anisotropic layer, containing the rod-shaped liquid crystal compound described below, was applied to the rubbing-treated film using a Gieser coating machine to form a composition layer. Next, the resulting composition layer was heated at 100°C for 80 seconds. This heating caused the rod-shaped liquid crystal compounds in the composition layer to be oriented in a predetermined direction. Subsequently, under oxygen-containing air (oxygen concentration: approximately 20 vol%) at 40°C, ultraviolet light was irradiated onto the composition layer for 1 second using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.). At this time, the maximum irradiation dose within the plane was 16.2 mJ / cm². 2 The minimum value is 15.8 mJ / cm². 2 That was the case. Next, the resulting composition layer was heated at 90°C for 10 seconds. Subsequently, under a nitrogen atmosphere at 55°C, the composition layer was irradiated with ultraviolet light using a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 ), an optically anisotropic layer with a fixed orientation state of the liquid crystal compound was formed, and an optical film (C) was fabricated.

[0250] ------------------------------------------------------------------ Composition for forming an optically anisotropic layer (B) ------------------------------------------------------------------ • 80 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (B) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.44 parts by mass of the above chiral agent (A) • 0.31 parts by mass of the above chiral agent (B) • 0.5 parts by mass of the above polymerizable polymer (X) • 0.08 parts by mass of the above polymer (A) • Methyl isobutyl ketone 117 parts by mass • Ethyl propionate 39 parts by mass ------------------------------------------------------------------

[0251] The optical film (C) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The optically anisotropic layer consisted of two layers exhibiting different optical anisotropy. The cellulose acylate film side layer (first layer) in the optically anisotropic layer was a layer in which a liquid crystal compound with a thickness (d1) of 2090 nm and twisted orientation with the thickness direction as the helical axis was fixed, and the air side layer (second layer) in the optically anisotropic layer was a layer in which a liquid crystal compound with a thickness (d2) of 1050 nm and twisted orientation with the thickness direction as the helical axis was fixed. Furthermore, the optical properties of the optical film (C) were determined using Axometrics' Axoscan and its analysis software (Multi-Layer Analysis). The product of Δn1 and thickness d1 at a wavelength of 550 nm in the first layer (Δn1d1) was 275 nm, the torsion angle of the liquid crystal compound was 26°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was 0° on the side in contact with the substrate and -26° on the side in contact with the second layer. Furthermore, the product of Δn2 and thickness d2 at a wavelength of 550 nm in the second layer (Δn2d2) was 138 nm, the twist angle of the liquid crystal compound was 78°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was -26° on the side in contact with the first layer and -104° on the air side. The orientation axis angle of the liquid crystal compound contained in the optical anisotropic layer is expressed by observing the substrate from the surface side of the optical anisotropic layer, with the longitudinal direction of the film as the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive. Furthermore, the torsional structure of the liquid crystal compound is represented here by observing the substrate from the surface side of the optically anisotropic layer, and using the orientation direction of the liquid crystal compound on the surface side (front side) as a reference, a clockwise (rightward) orientation of the liquid crystal compound on the substrate side (backward side) is represented as negative, and a counterclockwise (leftward) orientation is represented as positive.

[0252] (Fabrication of circular polarizing plates) A polarizer protective film, also prepared as described above, was bonded to one side of the polarizer prepared as described above using a polyvinyl alcohol-based adhesive to create a laminate containing the polarizer and the polarizer protective film positioned on one side of the polarizer. An adhesive (SK-2057, manufactured by Soken Chemical Co., Ltd.) was applied to the polarizer side (without the polarizer protective film) of the laminate prepared as described above to form an adhesive layer, and the optical film (C) prepared as described above was bonded to the adhesive layer and the cellulose acylate film so that they were in close contact. The absorption axis of the polarizer and the in-plane slow axis of the substrate-side surface of the first layer of the optical anisotropy layer in optical film (C) were parallel. Next, an adhesive was applied to the optical film (C) in the resulting laminate to form an adhesive layer. Following the procedure described above, a long circular polarizing plate (C) was fabricated in which a polarizer protective film, a polarizer, a cellulose acylate film, an optically anisotropic layer, and an adhesive layer were arranged in that order.

[0253] <Example 4> (Alkaline saponification treatment) The cellulose acylate film prepared by the method described in Example 1 was passed through a dielectric heating roll at a temperature of 60°C to raise the film surface temperature to 40°C. Then, an alkaline solution with the composition shown below was applied to the band surface of the film using a bar coater at a rate of 14 ml / m². 2 The material was coated and then transported for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd., heated to 110°C. Subsequently, using the same bar coater, 3 ml / m of pure water was applied. 2 The film was then coated. Next, it was washed with water using a fountain coater and dewatered with an air knife three times, and then transported to a 70°C drying zone for 10 seconds to dry, thereby producing an alkaline saponified cellulose acylate film.

[0254] ------------------------------------------------------------------ Alkaline solution ------------------------------------------------------------------ Potassium hydroxide 4.7 parts by mass Water 15.8 parts by mass Isopropanol 63.7 parts by mass Surfactants: C 14 H 29O(CH2CH2O) 20 H 1.0 parts by mass Propylene glycol 14.8 parts by mass ------------------------------------------------------------------

[0255] (Formation of orientation film) An orientation coating solution with the following composition was continuously applied to the surface of a cellulose acylate film that had undergone alkali saponification using a #14 wire bar. It was dried with 60°C hot air for 60 seconds, and then with 100°C hot air for 120 seconds.

[0256] ------------------------------------------------------------------ Orientation film coating solution ------------------------------------------------------------------ 28 parts by mass of the modified polyvinyl alcohol shown below Citrate ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass Photopolymerization initiator (Irgacure 2959, manufactured by BASF): 0.84 parts by mass Glutaraldehyde 2.8 parts by mass Water 699 parts by mass 226 parts by mass of methanol ------------------------------------------------------------------

[0257] (Modified polyvinyl alcohol)

[0258] [ka]

[0259] (Formation of optically anisotropic layer) The orientation film prepared as described above was subjected to a continuous rubbing process. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was set to 45°. If the longitudinal direction of the film (transport direction) is set to 90°, and when observed from the film side, with the film width direction as the reference (0°) and clockwise rotation represented as a positive value, the rotation axis of the rubbing roller is at 135°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 45° counterclockwise with respect to the longitudinal direction of the film.

[0260] Using the cellulose acylate film with the rubbing treatment described above as a substrate, a composition (C) for forming an optically anisotropic layer containing a rod-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine to form a composition layer (corresponding to step 1C). Next, the resulting composition layer was heated at 120°C for 80 seconds (corresponding to step 2C). This heating caused the rod-shaped liquid crystal compounds in the composition layer to be oriented in a predetermined direction. Subsequently, under oxygen-containing air (oxygen concentration: approximately 20 vol%) at 40°C, ultraviolet light was irradiated onto the composition layer for 1 second using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) (corresponding to step 3C). At this time, the maximum irradiation dose within the plane was 16.8 mJ / cm². 2 The minimum value is 16.3 mJ / cm². 2 That was the case. Next, the resulting composition layer was heated at 90°C for 10 seconds (corresponding to step 4C). Subsequently, under a nitrogen atmosphere at 55°C, the composition layer was irradiated with ultraviolet light using a metal halide lamp (manufactured by I-Graphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 ), an optically anisotropic layer with a fixed orientation state of the liquid crystal compound was formed (corresponding to step 5C), and an optical film (D) was fabricated.

[0261] Composition for forming optically anisotropic layers (C) ------------------------------------------------------------------ • 40 parts by mass of the following rod-shaped liquid crystal compound (D) • 40 parts by mass of the following rod-shaped liquid crystal compound (E) • 20 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.5 parts by mass of the above polymerizable polymer (X) • 0.08 parts by mass of the above polymer (A) • 3.0 parts by mass of the following ionic compound (A) • 0.4 parts by mass of the following photosensitive compound (A) • Methyl ethyl ketone 156 parts by mass ------------------------------------------------------------------

[0262] Rod-shaped liquid crystal compound (D)

[0263] [ka]

[0264] Rod-shaped liquid crystal compound (E)

[0265] [ka]

[0266] Ionic compound (A)

[0267] [ka]

[0268] Photosensitive compound (A)

[0269] [ka]

[0270] Furthermore, the fluorine-containing compound (A) in the optical anisotropic layer-forming composition (C) is irradiated with light at 365 nm (16.6 mJ / cm²). 2 This resulted in the formation of a decomposition product (A) having a hydrophilic carboxyl group.

[0271] Decomposition product (A)

[0272] [ka]

[0273] The optical film (D) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The optically anisotropic layer consisted of two layers exhibiting different optical anisotropy. The cellulose acylate film side layer (first layer) in the optically anisotropic layer was a layer in which a homogeneously oriented liquid crystal compound with a thickness (d1) of 3000 nm was fixed, and the air side layer (second layer) in the optically anisotropic layer was a layer in which a homeotropically oriented liquid crystal compound with a thickness (d2) of 1300 nm was fixed. Furthermore, the optical properties of the optical film (D) were determined using Axometrics' Axoscan and its analysis software (Multi-Layer Analysis). The product of Δn1 and d1 (Δn1d1) at a wavelength of 550 nm in the first layer was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°. Furthermore, the product of Δn2 and d2 (Δn2d2) at a wavelength of 550 nm in the second layer was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm was -60 nm. The angle of the in-plane slow axis is expressed by observing the substrate from the surface side of the optically anisotropic layer, with the longitudinal direction of the film as the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive.

[0274] (Fabrication of circular polarizing plates) A polarizer protective film, also prepared as described above, was bonded to one side of the polarizer prepared as described above using a polyvinyl alcohol-based adhesive to create a laminate containing the polarizer and the polarizer protective film positioned on one side of the polarizer. An adhesive (SK-2057, manufactured by Soken Chemical Co., Ltd.) was applied to the polarizer side (without the polarizer protective film) of the laminate prepared as described above to form an adhesive layer, and the optical film (D) prepared as described above was bonded to the adhesive layer and the cellulose acylate film so that they were in close contact. The angle between the absorption axis of the polarizer and the in-plane slow phase axis of the optical anisotropy layer in the optical film (D) was 45°. Next, an adhesive was applied to the optical film (D) in the resulting laminate to form an adhesive layer. Following the procedure described above, a long circular polarizing plate (D) was fabricated in which a polarizer protective film, a polarizer, a cellulose acylate film, an optically anisotropic layer, and an adhesive layer were arranged in that order.

[0275] <Example 5> (Formation of optically anisotropic layer) The cellulose acylate film prepared in Example 1 was subjected to continuous rubbing. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 90°.

[0276] Using the cellulose acylate film treated with the above rubbing process as a substrate, a composition (D) for forming an optically anisotropic layer containing a rod-shaped liquid crystal compound with the following composition was applied using a Gieser coating machine to form a composition layer (corresponding to step 1B). The absolute value of the helical induced force of the chiral agent in the composition layer in step 1B was 31 μm -1 That was the case. Next, the resulting composition layer was heated at 100°C for 80 seconds (corresponding to step 2B). This heating caused the rod-shaped liquid crystal compounds in the composition layer to be oriented in a predetermined direction. Subsequently, under oxygen-containing air (oxygen concentration: approximately 20 vol%) at 40°C, ultraviolet light was irradiated onto the composition layer for 1 second using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) (corresponding to step 3B). At this time, the maximum irradiation dose within the plane was 13.4 mJ / cm². 2 The minimum value is 13.1 mJ / cm². 2 That was the case. Next, the resulting composition layer was heated at 90°C for 10 seconds (corresponding to step 4B). Subsequently, under a nitrogen atmosphere at 55°C, the composition layer was irradiated with ultraviolet light using a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 ), an optically anisotropic layer with a fixed orientation state of the liquid crystal compound was formed (corresponding to step 5B), and an optical film (E) was fabricated.

[0277] Composition of composition (D) for forming an optically anisotropic layer ------------------------------------------------------------------ • 80 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (B) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 11 parts by mass of the above chiral agent (B) • 0.5 parts by mass of the above polymerizable polymer (X) • 0.08 parts by mass of the above polymer (A) • Methyl isobutyl ketone 117 parts by mass • Ethyl propionate 39 parts by mass ------------------------------------------------------------------

[0278] The optical film (E) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a scanning electron microscope (SEM). The optically anisotropic layer consisted of two layers exhibiting different optical anisotropies. The cellulose acylate film side layer (first layer) had a thickness (d1) of 1800 nm, and the air side layer (second layer) had a thickness (d2) of 1800 nm. The first and second layers each had cholesteric orientations with different helical pitches. Furthermore, the spectral reflectance characteristics of the optical film (E) were determined using an integral reflectometer. It was confirmed to be a two-band cholesteric liquid crystal film having a reflectance band centered at 450 nm originating from the first layer and a reflectance band centered at 650 nm originating from the second layer.

[0279] <Example 6> (Formation of optically anisotropic layer) The cellulose acylate film prepared in Example 1 was subjected to continuous rubbing. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was 45°. If we consider the longitudinal direction of the film (transport direction) to be 90°, and observe from the cellulose acylate film side, with the width direction of the cellulose acylate film as the reference (0°) and the counterclockwise direction as a positive value, the rotation axis of the rubbing roller was 135°. In other words, the position of the rotation axis of the rubbing roller was rotated 45° clockwise relative to the longitudinal direction of the cellulose acylate film.

[0280] Using the cellulose acylate film that underwent the rubbing process described above as a substrate, a composition (E) for forming an optically anisotropic layer containing a rod-shaped liquid crystal compound with the following composition was applied using a Gieser coating machine to form a composition layer (corresponding to step 1D). Next, the resulting composition layer was heated at 80°C for 60 seconds (corresponding to step 2D). This heating caused the rod-shaped liquid crystal compounds in the composition layer to be oriented in a predetermined direction. Subsequently, under oxygen-containing air (oxygen concentration: approximately 20 vol%) at 40°C, ultraviolet light was irradiated onto the composition layer for 1 second using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) (corresponding to step 3B). At this time, the maximum irradiation dose within the plane was 11.9 mJ / cm². 2 The minimum value is 11.6 mJ / cm². 2 That was the case. Next, the resulting composition layer was heated at 130°C for 10 seconds (corresponding to step 4D). The phase transition temperature of the rod-shaped liquid crystal compound in the optically anisotropic layer-forming composition (D) to the isotropic phase was 110°C. Subsequently, under a nitrogen atmosphere, the composition layer was irradiated with ultraviolet light at 130°C using a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 ), an optically anisotropic layer with a fixed orientation state of the liquid crystal compound was formed (corresponding to step 5D), and an optical film (F) was fabricated.

[0281] Composition for forming optically anisotropic layers (E) ------------------------------------------------------------------ • 80 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (B) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.5 parts by mass of the above polymerizable polymer (X) • 0.08 parts by mass of the above polymer (A) • Methyl isobutyl ketone 117 parts by mass • Ethyl propionate 39 parts by mass ------------------------------------------------------------------

[0282] The optical film (F) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The optically anisotropic layer consisted of two layers exhibiting different optical anisotropy. The cellulose acylate film side layer (first layer) in the optically anisotropic layer was a layer with a thickness (d1) of 1100 nm and a homogeneously oriented liquid crystal compound fixed within it, while the air side layer (second layer) in the optically anisotropic layer had a thickness (d2) of 1600 nm and the liquid crystal compound was in an isotropic state. The optical properties of the optical film (F) were determined using Axometrics' Axoscan and its analysis software (Multi-Layer Analysis). The product of Δn1 and thickness d1 at a wavelength of 550 nm (Δn1d1) of the first layer was 140 nm, and the in-plane slow axis was -45°. The product of Δn1 and thickness d1 at a wavelength of 550 nm (Δn2d2) (in-plane retardation at a wavelength of 550 nm) of the second layer was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm was 0 nm. The angle of the in-plane slow axis is expressed by observing the substrate from the surface side of the optically anisotropic layer, with the longitudinal direction of the film as the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive.

[0283] (Fabrication of circular polarizing plates) A polarizer protective film, also prepared as described above, was bonded to one side of the polarizer prepared as described above using a polyvinyl alcohol-based adhesive to create a laminate containing the polarizer and the polarizer protective film positioned on one side of the polarizer. An adhesive (SK-2057, manufactured by Soken Chemical Co., Ltd.) was applied to the polarizer side (without the polarizer protective film) of the laminate prepared as described above to form an adhesive layer, and the optical film (F) prepared as described above was bonded to the adhesive layer and the cellulose acylate film so that they were in close contact. The angle between the absorption axis of the polarizer and the in-plane slow phase axis of the optical anisotropy layer in the optical film (F) was 45°. Next, an adhesive was applied to the optical film (F) in the resulting laminate to form an adhesive layer. Following the procedure described above, a long circular polarizing plate (F) was fabricated in which a polarizer protective film, a polarizer, a cellulose acylate film, an optically anisotropic layer, and an adhesive layer were arranged in that order.

[0284] <Comparative Example 1> (Formation of optically anisotropic layer) The cellulose acylate film prepared as described above was subjected to a continuous rubbing process. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was 72°. If we consider the longitudinal direction of the film (transport direction) to be 90°, and observe from the cellulose acylate film side, with the width direction of the cellulose acylate film as the reference (0°) and the counterclockwise direction as a positive value, the rotation axis of the rubbing roller was 18°. In other words, the position of the rotation axis of the rubbing roller was rotated 72° clockwise relative to the longitudinal direction of the cellulose acylate film.

[0285] Using the cellulose acylate film treated with the above rubbing process as a substrate, an optically anisotropic layer-forming composition (F) containing a rod-shaped liquid crystal compound with the following composition was applied using a Gieser coating machine to form a composition layer. Next, the resulting composition layer was heated at 100°C for 80 seconds. Subsequently, under a nitrogen atmosphere and at 55°C, the composition layer is irradiated with light from a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2 By doing so, the liquid crystal compound was immobilized, and an optically anisotropic layer was formed. On the optically anisotropic layer prepared as described above, an optically anisotropic layer-forming composition (G) containing a rod-shaped liquid crystal compound with the following composition was applied using a Gieser coating machine to form a composition layer. Next, the resulting composition layer was heated at 100°C for 80 seconds. Subsequently, under a nitrogen atmosphere and at 55°C, the composition layer is irradiated with light from a metal halide lamp (manufactured by iGraphics Co., Ltd.) (irradiation dose: 500 mJ / cm²). 2By immobilizing the liquid crystal compound, an optically anisotropic layer was formed, and an optical film (G) was fabricated.

[0286] ------------------------------------------------------------------ Composition for forming optically anisotropic layers (F) ------------------------------------------------------------------ • 80 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (B) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.5 parts by mass of the above polymerizable polymer (X) • Methyl isobutyl ketone 117 parts by mass • Ethyl propionate 39 parts by mass ------------------------------------------------------------------

[0287] ------------------------------------------------------------------ Composition for forming optically anisotropic layers (G) ------------------------------------------------------------------ • 80 parts by mass of the above-mentioned rod-shaped liquid crystal compound (A) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (B) • 10 parts by mass of the above-mentioned rod-shaped liquid crystal compound (C) • Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass • Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by mass • 0.6 parts by mass of the above chiral agent (A) • 0.08 parts by mass of the above polymer (A) • Methyl ethyl ketone 156 parts by mass ------------------------------------------------------------------

[0288] The optical film (G) prepared as described above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The optically anisotropic layer consisted of two layers exhibiting different optical anisotropy. The cellulose acylate film side layer (first layer) of the optically anisotropic layer was a layer in which a homogeneously oriented liquid crystal compound with a thickness (d1) of 1310 nm was fixed, and the air side layer (second layer) of the optically anisotropic layer was a layer in which a liquid crystal compound with a thickness (d2) of 1390 nm was fixed, which was twisted oriented with the thickness direction as the helical axis. Furthermore, the optical properties of the optical film (A) were determined using Axometrics' Axoscan and its analysis software (Multi-Layer Analysis). The product of Δn1 and thickness d1 at a wavelength of 550 nm in the first layer (Δn1d1) was 173 nm, the torsion angle of the liquid crystal compound was 0°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was -10° on the side in contact with the substrate and -10° on the side in contact with the second layer. Furthermore, the product of Δn2 and thickness d2 at a wavelength of 550 nm in the second layer (Δn2d2) was 184 nm, the twist angle of the liquid crystal compound was 75°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film was -10° on the side in contact with the first layer and -85° on the air side. The orientation axis angle of the liquid crystal compound contained in the optical anisotropic layer is expressed by observing the substrate from the surface side of the optical anisotropic layer, with the longitudinal direction of the film as the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive. Furthermore, the torsional structure of the liquid crystal compound is represented here by observing the substrate from the surface side of the optically anisotropic layer, and using the orientation direction of the liquid crystal compound on the surface side (front side) as a reference, a clockwise (rightward) orientation of the liquid crystal compound on the substrate side (backward side) is represented as negative, and a counterclockwise (leftward) orientation is represented as positive.

[0289] (Fabrication of circular polarizing plates) A circular polarizer (G) was fabricated following the same procedure as in Example 1, except that optical film (G) was used instead of optical film (A).

[0290] <Comparative Example 2> When irradiating with light from a 365nm LED lamp (manufactured by Acroedge Co., Ltd.), the output is adjusted to set the maximum irradiation dose within the plane to 13.7 mJ / cm². 2 The minimum value was 12.4 mJ / cm². 2 Except as otherwise provided, the optical film (H) and circular polarizer (H) were prepared using the same procedure as in Example 1. <Rating> (Measurement of thickness variations in optically anisotropic layers) Following the procedure described above, in each of the 64 sub-regions obtained by dividing the largest possible square on the surface of the optical anisotropy layer in the fabricated optical films (A) to (H) equally into 8 sections vertically and horizontally, the optical anisotropy layer was cut parallel to the rubbing direction passing through the center of the sub-region. From the exposed cross-section, the thickness d1 of the first layer and the thickness d2 of the second layer were measured, and the maximum value (Xmax), minimum value (Xmin), and ratio (Xmax / Xmin) of the ratio X (=d1 / (d1+d2)) of thickness d1 to the total layer thickness (d1+d2) were calculated.

[0291] (Evaluation of uniformity in visibility in OLED mounting configurations (OLED mounting evaluation)) An LG Electronics OLED55B8PJA equipped with an organic EL panel (organic EL display element) was disassembled, the touch panel with circular polarizers was peeled off from the organic EL display device, and the circular polarizers (A) to (D) and (F) to (H) prepared above were bonded to it while ensuring no air was trapped inside, thereby creating an organic EL display device, and the visibility of color unevenness was evaluated. A: No unevenness is visible at all (acceptable) B: Although some unevenness is visible, it is very slight (acceptable). C: Unevenness is visible and unacceptable.

[0292] (Evaluation of uniformity visibility under diffuse light source (reflection evaluation)) The fabricated optical film (E) was placed under a diffuse light source, and the visibility of reflective color unevenness was evaluated. A: No unevenness is visible at all (acceptable) B: Although some unevenness is visible, it is very slight (acceptable). C: Unevenness is visible and unacceptable.

[0293] In Table 1, "homogeneous" means that the liquid crystal compound is homogeneously oriented. "Twisted" means that the liquid crystal compound is twisted along a helical axis extending in the thickness direction. "Homeotropic" means that the liquid crystal compound is homeotropically oriented. "Cholesteric" means that the liquid crystal compound is cholesterically oriented. "Isotropic" means that the liquid crystal compound is in an isotropic phase state.

[0294] [Table 1]

[0295] As shown in the table above, the optical anisotropy layer of the present invention exhibited the desired effect. In particular, a comparison between Examples 1 and 2 confirmed that a superior effect is obtained when the relationship in equation (2B) is satisfied. [Explanation of Symbols]

[0296] 10, 100, 200, 300, 400, 500, 600 Optical anisotropic layer 12,102,200A,300A,400A,500A,600A (First Layer) 14,104,200B,300B,400B,500B,600B 2nd layer 16 Subregions 18 circuit boards 22 Other optically anisotropic layers 24-layer structure 26 Polarizers 28. Optically anisotropic layer with polarizer 202,302,402,502,602 Composition layer 202A, 302A, 402A, 502A, 602A Lower area 202B, 302B, 402B, 502B, 602B Upper side area

Claims

1. An optically anisotropic layer formed using a liquid crystal compound, The optically anisotropic layer has a first layer and a second layer in direct contact with the first layer, along the thickness direction. The orientation state of the liquid crystal compound in the first layer is different from the orientation state of the liquid crystal compound in the second layer. The region within the largest possible square that can be drawn on the surface of the optical anisotropy layer is subdivided into 64 square sub-regions of the same area, the thickness d1 of the first layer and the thickness d2 of the second layer at the center of each sub-region are determined, and X represented by equation (1) is calculated for each sub-region, and when the maximum value of the 64 calculated X values ​​is taken as Xmax and the minimum value as Xmin, the relationship in equation (2A) is satisfied. The first layer is a layer in which the orientation state of a homogeneously oriented liquid crystal compound is fixed. An optically anisotropic layer in which the thickness ratio of the first layer to the second layer (thickness of the first layer / thickness of the second layer) is 0.1 to 3.

0. Formula (1) X=d1 / (d1+d2) Formula (2A) Xmax / Xmin<1.10

2. The optical anisotropy layer according to claim 1, satisfying the relationship of formula (2B). Formula (2B) Xmax / Xmin<1.09

3. The optical anisotropic layer according to claim 1 or 2, wherein the second layer is a layer in which the orientation state of a liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction is fixed.

4. The second layer is an optically anisotropic layer in which the orientation state of the liquid crystal compound is fixed, The optical anisotropic layer according to claim 1 or 2, wherein the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the first layer is different from the inclination angle of the orientation direction of the liquid crystal compound with respect to the layer surface in the second layer.

5. The optical anisotropic layer according to claim 1 or 2, wherein the second layer is a layer in which the orientation state of the homeotropically oriented liquid crystal compound is fixed.

6. The optical anisotropic layer according to claim 1 or 2, wherein the second layer is a layer in which the liquid crystal compound is fixed in an isotropic phase state.

Images