Alignment film, optical film, and image display device

Abstract

To provide an alignment film capable of improving alignment of a liquid crystal compound, and to provide an optical film and image display device.SOLUTION: An alignment film 20 disclosed herein has a plurality of patterned areas 25. Each patterned area 25 has a plurality of asperities 21. A longitudinal direction of the asperities 21 is different between adjacent patterned areas 25. The area of each patterned area 25 is in a range of 0.015 μm2 to 10 μm2, inclusive.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an alignment film, an optical film, and an image display device. [Background technology]

[0002] Image display devices using liquid crystal compounds are used in various fields (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses an optical device including a liquid crystal layer having a first plurality of liquid crystal molecules arranged in a first pattern and a second plurality of liquid crystal molecules arranged in a second pattern. Patent Document 1 also discloses alignment of the liquid crystal molecules by using nanoimprint technology.

[0004] In such an optical device disclosed in Patent Document 1, the molecules (liquid crystal compounds) of the liquid crystal layer are arranged in predetermined domains, and the orientation of the vertical axis (slow axis) of the liquid crystal molecules in the domains is configured to gradually change for each domain. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2019-536100 Summary of the Invention [Problem to be solved by the invention]

[0006] When the orientation of the slow axis of the liquid crystal compound is configured to gradually change along a predetermined direction, a portion where the liquid crystal compound is densely arranged and a portion where the liquid crystal compound is sparsely arranged may be formed. When a portion where the liquid crystal compound is sparsely arranged is formed, the alignment of the liquid crystal compound may be reduced in the portion where the liquid crystal compound is sparsely arranged.

[0007] The present disclosure has been made in consideration of the above points, and has an object to provide an alignment film, an optical film, and an image display device that are capable of improving the alignment of a liquid crystal compound. [Means for solving the problem]

[0008] The embodiments of the present disclosure relate to the following [1] to [9].

[0009] [1] An alignment film, A plurality of pattern areas are provided, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, The area of ​​each of the pattern regions is 0.015 μm 2 More than 10μm 2 Below is the alignment film.

[0010] [2] An alignment film, A plurality of pattern regions are arranged along a first direction, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, An alignment film, wherein when each of the pattern regions is divided into six equal parts along the first direction, the minimum ratio of the area of ​​the concave parts of the unevenness to the area of ​​the part in each of the parts is 90% or more and 99.5% or less of the maximum ratio.

[0011] [3] An alignment film, A plurality of pattern areas are provided, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, An alignment film, wherein the ratio of the area of ​​the concave portions of the unevenness to the area of ​​the pattern region in one of the adjacent pattern regions is 90% or more and 110% or less of the ratio of the area of ​​the concave portions of the unevenness to the area of ​​the pattern region in the other pattern region.

[0012] [4] The alignment film according to any one of [1] to [3], wherein a gap is provided between the pattern regions.

[0013] [5] The alignment film according to any one of [1] to [4], wherein the pattern region extends along the direction in which the projections and recesses extend.

[0014] [6] The pattern regions are arranged along a first direction; The length of the pattern area along the first direction is L1, In the pattern region, when the length of the longest recess is L2, L1≦L2 The alignment film according to any one of [1] to [5], which satisfies the following relationship:

[0015] [7] A base material layer; An alignment film according to any one of [1] to [6], laminated on the base layer; A retardation layer is laminated on the alignment film, The optical film, wherein the base layer, the alignment film, and the retardation layer are laminated in this order.

[0016] [8] [7] The optical film according to the present invention; and a display device laminated on the optical film.

[0017] [9] The image display device according to [8], further comprising a polarizing plate disposed between the optical film and the display device, or on the opposite side of the optical film from the display device. Effect of the Invention

[0018] According to the embodiments of the present disclosure, the alignment of liquid crystal compounds can be improved. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing an image display device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing an image display device according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing an image display device according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing an optical film according to an embodiment. [Diagram 5] FIG. 5 is a plan view showing an alignment film according to an embodiment. [Figure 6] FIG. 6 is a cross-sectional view (cross-sectional view taken along line VI-VI in FIG. 5) showing an alignment film according to one embodiment. [Figure 7] FIG. 7 is a plan view showing another example of the alignment film according to the embodiment. [Figure 8] FIG. 8 is a plan view showing another example of the alignment film according to the embodiment. [Figure 9] FIG. 9 is a plan view showing another example of the alignment film according to the embodiment. [Figure 10] FIG. 10 is a plan view showing another example of the alignment film according to the embodiment. [Figure 11] FIG. 11 is a plan view showing another example of the alignment film according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, the scale and the aspect ratio are appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0021] The terms used in this specification that specify shapes and geometric conditions, as well as the degree thereof, such as "parallel," "perpendicular," "same," and the values ​​of lengths and angles, are not to be bound by their strict meanings, but are to be interpreted to include the range within which similar functions can be expected.

[0022] In this specification, terms such as "film," "sheet," and "plate" are not terms that are distinguished from one another solely on the basis of differences in name. For example, a "film" cannot be distinguished from a member called a sheet or plate solely on the basis of differences in name.

[0023] First, the configuration of an image display device according to the present embodiment will be described with reference to FIGS.

[0024] As shown in FIGS. 1 to 3, the image display device 1 according to the present embodiment includes an optical film 10 and a display device 50 laminated on the optical film 10. The image display device 1 may further include a polarizing plate 40. In this case, as shown in FIG. 1, the polarizing plate 40 may be disposed between the optical film 10 and the display device 50. As shown in FIG. 2, the polarizing plate 40 may be disposed on the opposite side of the optical film 10 to the display device 50. As shown in FIGS. 1 and 3, the image display device 1 may further include an ultraviolet ray cut film 60. Here, the optical film 10 will be first described.

[0025] As shown in Fig. 4, the optical film 10 includes a base layer 11, an alignment film 20 laminated on the base layer 11, and a retardation layer 30 laminated on the alignment film 20. The base layer 11, the alignment film 20, and the retardation layer 30 may be laminated in this order. In this case, the retardation layer 30 may be disposed closer to the viewer (the positive side of the lamination direction Z) than the base layer 11. Although not shown, a primer layer may be provided between the base layer 11 and the alignment film 20.

[0026] Next, each layer of the optical film 10 will be described in detail.

[0027] <Base material layer> The base layer 11 is a layer that plays a role of supporting and protecting the retardation layer 30. The base layer 11 may be an optically isotropic layer. The base layer 11 may be a layer formed from a polymer, or may be a layer formed from glass. As the polymer constituting the base layer 11, cellulose acylate, polycarbonate-based polymer, polyester-based polymer such as polyethylene terephthalate or polyethylene naphthalate, acrylic polymer such as polymethyl methacrylate, or styrene-based polymer such as polystyrene or acrylonitrile-styrene copolymer (AS resin), etc. can be used. In addition, examples of the polymer constituting the base layer 11 include polyolefins such as polyethylene and polypropylene, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon or aromatic polyamide, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinylidene chloride-based polymers, vinyl alcohol-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and mixtures of these polymers. The in-plane retardation of the base layer 11 is preferably 20 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, even more preferably 1 nm or less, and most preferably 0 nm. The wavelength λ of light serving as the reference for the retardation is 550 nm. The measurement is performed in low retardation mode using a measuring device KOBRA-WR manufactured by Oji Scientific Instruments.

[0028] When the base layer 11 is made of a polymer, the thickness of the base layer 11 may be about 25 μm or more and 125 μm or less. When the base layer 11 is made of glass, the thickness of the base layer 11 may be about 100 μm or more and 5 mm or less.

[0029] <Alignment film> The alignment film 20 serves to facilitate alignment of the liquid crystal compound in the retardation layer 30 when the retardation layer 30 is formed.

[0030] The alignment film 20 may be prepared, for example, by applying a resin composition onto the base layer 11 and imparting an alignment regulating force. The alignment film 20 may contain a UV-curable resin. That is, the resin composition for forming the alignment film 20 may be a UV-curable resin. Specific examples of the UV-curable resin include a material obtained by adding a photopolymerization initiator and any additive to a single or mixed material such as a polymerizable oligomer or monomer having an acryloyl group, such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, or melamine acrylate, and a polymerizable oligomer or monomer having a polymerizable vinyl group, such as acrylic acid, acrylamide, acrylonitrile, or styrene. The material of the alignment film 20 may be, for example, a thermosetting resin or an electron beam curing resin.

[0031] Here, as shown in FIG. 5 and FIG. 6, in this embodiment, the alignment film 20 has a plurality of pattern regions 25. The pattern regions 25 are arranged along a first direction X and a second direction perpendicular to the first direction X. The first direction X and the second direction Y are directions perpendicular to the lamination direction Z of the optical film 10. The pattern regions 25 of the alignment film 20 may be arranged along a curve (for example, a meandering curve). In this case, the direction of the diffracted light can be varied, making it difficult for a viewer to observe the diffracted light. Therefore, deterioration of visibility caused by the diffracted light can be suppressed compared to the case where the diffracted light is reflected in one direction.

[0032] In this embodiment, the shape of the pattern region 25 is a square in a plan view (see the imaginary line (two-dot chain line) in FIG. 5). The area of ​​each pattern region 25 is 0.015 μm 2 More than 1000μm 2 It may be less than 0.015 μm. 2 More than 10μm 2 It may be less than 1 μm, for example. 2The area of ​​the pattern region 25 may be 0.015 μm 2 By satisfying the above conditions, the shape of the irregularities 21 can be improved when the alignment film 20 is produced by an imprint method. 2 or less, it is possible to effectively suppress poor alignment of the liquid crystal compound in the pattern region 25. That is, by reducing the area of ​​the pattern region 25, it is possible to suppress the formation of a portion where the liquid crystal compound is sparsely arranged, even when the longitudinal direction of the recesses 22 of the unevenness 21 described later is changed stepwise. Therefore, it is possible to improve the alignment of the liquid crystal compound.

[0033] The shape of each pattern region 25 may be a square, or may be, for example, a rectangle, a quadrangle such as a rhombus, or a polygon such as a triangle or a hexagon. The length L1 (length in the first direction X) of each pattern region 25 may be, for example, 0.125 μm or more and 10 μm or less. The length L1 of each pattern region 25 may be the same as or different from each other.

[0034] Each pattern region 25 has a plurality of concaves and convexes 21. The concaves and convexes 21 correspond to the slow axis of the retardation layer 30. That is, the concaves 22 of the concaves and convexes 21 are configured to have the liquid crystal compound of the retardation layer 30, which will be described later, disposed therein. This allows the liquid crystal compound of the retardation layer 30 provided on the alignment film 20 to be aligned in a predetermined direction along the concaves 22 of the concaves and convexes 21. For example, when it is desired to change the direction of the in-plane slow axis of the retardation layer 30, the alignment direction of the liquid crystal compound is changed by changing the longitudinal direction of the concaves 22 for each pattern region 25. This allows the direction of the in-plane slow axis to be changed for each pattern region 25. In this case, for example, the concaves and convexes 21 may be formed by an imprint method.

[0035] In addition, the longitudinal directions of the irregularities 21 are different in pattern regions 25 adjacent to each other along the first direction X. On the other hand, the longitudinal directions of the irregularities 21 are substantially the same in pattern regions 25 adjacent to each other along the second direction Y.

[0036] Moreover, each pattern region 25 is configured such that the longitudinal direction of the unevenness 21 (i.e., the direction of the slow axis in the plane of the retardation layer 30) changes stepwise along the first direction X. That is, the angle of the tangent of the recess 22 with respect to the second direction Y changes stepwise along the first direction X. Here, the tangent of the recess 22 means the tangent of the recess 22 at the center of the pattern region 25 in the first direction X. By changing the direction of the slow axis stepwise, poor alignment of the liquid crystal compound between the optical axis pattern regions Pa can be suppressed, which is preferable.

[0037] In the example shown in Fig. 5, the recesses 22 of the unevenness 21 extend in a curved line. More specifically, the recesses 22 extend in an arc. The recesses 22 may be arranged so that when certain recesses 22 are connected to each other, they form one arc Ca. That is, a plurality of recesses 22 may be formed so as to be arranged on concentric circles. This is preferable because the direction of the slow axis changes stepwise, and poor alignment of the liquid crystal compound between the pattern regions 25 can be suppressed.

[0038] The depth of the recesses 22 is preferably 2 nm or more and 200 nm or less, more preferably 10 nm or more and 100 nm or less, and even more preferably 20 nm or more and 50 nm or less. By making the depth of the recesses 22 2 nm or more, it is possible to more easily align a liquid crystal compound (liquid crystal molecules) described later along the recesses 22. By making the depth of the recesses 22 200 nm or less, it is possible to more easily peel the alignment film 20 from the shaping plate described later, and therefore it is possible to more easily and stably form the unevenness 21 of the alignment film 20.

[0039] Furthermore, when each pattern region 25 is equally divided into six parts along the first direction X, the ratio of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the part in each part may be 35% or more and 70% or less. That is, when each pattern region 25 is equally divided into six parts, a first part 25a to a sixth part 25f, in the first part 25a, the ratio ra of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the first part 25a may be 35% or more and 70% or less. Similarly, in the second part 25b, the ratio rb of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the second part 25b may be 35% or more and 70% or less. Furthermore, in the third part 25c, the ratio rc of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the third part 25c may be 35% or more and 70% or less. In addition, in the fourth portion 25d, a ratio rd of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the fourth portion 25d may be 35% or more and 70% or less. In addition, in the fifth portion 25e, a ratio re of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the fifth portion 25e may be 35% or more and 70% or less. Furthermore, in the sixth portion 25f, a ratio rf of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the sixth portion 25f may be 35% or more and 70% or less.

[0040] In addition, the minimum value of the ratio in the six parts (the first part 25a to the sixth part 25f) may be 90% or more and 99.5% or less of the maximum value of the ratio in the six parts. For example, in the above-mentioned ratios ra to rf, if the maximum value of the ratio is rc and the minimum value of the ratio is ra, 90(%)≦(ra / rc)×100≦99.5(%) The following relationship may be satisfied. In this way, the minimum value of the ratio in the six parts (the first part 25a to the sixth part 25f) is 90% or more of the maximum value of the ratio in the six parts, so that the formation of a part in which the liquid crystal compound is sparsely arranged in the pattern region 25 can be suppressed. Therefore, the alignment of the liquid crystal compound can be improved. Furthermore, the minimum value of the ratio in the six parts (the first part 25a to the sixth part 25f) is 99.5% or less of the maximum value of the ratio in the six parts, so that the difference in the ratio in the six parts can be reduced. Here, when the difference in the ratio is large between adjacent parts, the liquid crystal compound in the part with the large ratio may affect the alignment direction of the liquid crystal compound in the part with the small ratio. For example, the alignment direction may be forcibly changed so that the alignment direction of the liquid crystal compound in the part with the small ratio approaches the alignment direction of the liquid crystal compound in the part with the large ratio. In contrast, by reducing the difference in the ratio in the six parts, it is possible to suppress the liquid crystal compound in a specific part from affecting the alignment direction of the liquid crystal compound in the adjacent part. Therefore, it is possible to suppress the occurrence of abnormalities in the alignment direction of the liquid crystal compound. As a result, the alignment of the liquid crystal compound can be improved.

[0041] In each pattern region 25, the ratio of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the pattern region 25 may be 35% or more and 70% or less. When the ratio of the area of ​​the recesses 22 to the area of ​​the pattern region 25 is 35% or more, the liquid crystal compound can be densely arranged. This improves the alignment of the liquid crystal compound. Furthermore, when the ratio of the area of ​​the recesses 22 to the area of ​​the pattern region 25 is 70% or less, the shapeability of the unevenness 21 can be improved when the alignment film 20 is produced by the imprint method.

[0042] In addition, the ratio of the area of ​​the recesses 22 of the irregularities 21 to the area of ​​the pattern region 25 may be different from each other in each pattern region 25. As an example, in the pattern region 25A, the area of ​​the pattern region 25A is 1 μm 2 The area of ​​the recess 22 may be 0.633 μm 2The ratio of the area of ​​the recess 22 to the area of ​​the pattern region 25A may be 63.3%. On the other hand, in the pattern region 25B, the area of ​​the pattern region 25B is 1 μm 2 The area of ​​the recess 22 may be 0.646 μm 2 The ratio of the area of ​​the recess 22 to the area of ​​the pattern region 25B may be 64.6%. In the pattern region 25C, the area of ​​the pattern region 25C may be 1 μm 2 The area of ​​the recess 22 may be 0.676 μm 2 The ratio of the area of ​​the recesses 22 to the area of ​​the pattern region 25C may be 67.6%.

[0043] In the present embodiment, the ratio in one pattern region 25 may be 90% or more and 110% or less of the ratio in the other pattern region 25 in adjacent pattern regions 25. By making the ratio in one pattern region 25 90% or more of the ratio in the other pattern region 25, it is possible to suppress alignment defects of the liquid crystal compound between the pattern regions 25. Also, by making the ratio in one pattern region 25 110% or less of the ratio in the other pattern region 25, it is possible to reduce the difference in ratio between the pattern regions 25. Here, when the difference in ratio is large between adjacent pattern regions 25, the liquid crystal compound in the pattern region 25 with the large ratio may affect the alignment direction of the liquid crystal compound in the pattern region 25 with the small ratio. In contrast, by making the difference in ratio between the pattern regions 25 small, it is possible to suppress the liquid crystal compound in a certain pattern region 25 from affecting the alignment direction of the liquid crystal compound in the adjacent pattern region 25. Therefore, it is possible to suppress the occurrence of abnormalities in the alignment direction of the liquid crystal compound. As a result, it is possible to improve the alignment of the liquid crystal compound.

[0044] In addition, when the length of the longest recess 22 in the pattern region 25 is L2, L1≦L2 The following relationship may be satisfied: 1.2×L1≦L2 It is preferable that the following relationship is satisfied. This allows the length of the recess 22 to be longer than the length L1 of the pattern region 25, thereby improving the alignment of the liquid crystal compound. Note that L2 may be 500 nm or more and 4 μm or less.

[0045] A gap G is provided between such pattern regions 25. It is possible to suppress the formation of portions where the liquid crystal compound is sparsely arranged, while allowing the longitudinal direction of the unevenness 21 to change stepwise. In the first direction X and the second direction Y, the width W of the gap G may be 5 nm or more and 50 nm or less.

[0046] The means for imparting an alignment regulating force (unevenness) to the alignment film 20 may be a conventionally known means. For example, an imprint method is an example of the means for imparting an alignment regulating force to the alignment film 20. When the alignment film 20 is produced by the imprint method, it is preferable to use an electronically cured resin in order to prevent deformation after curing.

[0047] <<<Imprint method>>> Next, a method for producing the alignment film 20 by an imprint method will be described. The unevenness of the alignment film 20 can be formed, for example, by shaping a layer containing a resin using a plate having a shape complementary to the surface shape of the alignment film 20. More specifically, the alignment film 20 can be formed, for example, by the following steps 1 and 2.

[0048] Step 1: A step of applying a coating liquid for forming an alignment film containing a resin onto a base layer 11 to form a layer containing a resin. Step 2: A step of shaping a layer containing a resin using a plate having a shape complementary to the surface shape of the alignment film 20.

[0049] When the alignment film 20 is produced by the imprint method, first, in step 1, a coating liquid for forming an alignment film containing a resin is applied onto the base layer 11 to form a layer containing a resin. When the coating liquid for forming an alignment film contains a solvent, it is preferable to dry the solvent in step 1.

[0050] When a curable resin is used as the resin, it is preferable to use a coating liquid for forming an alignment film containing a curable resin composition as the coating liquid for forming an alignment film in step 1. That is, when a curable resin is used as the resin, it is preferable that the curable resin in the coating liquid for forming an alignment film in step 1 is in an uncured state.

[0051] When a coating liquid for forming an alignment film containing an ionizing radiation curable resin composition is used as the coating liquid for forming an alignment film in step 1, it is preferable to cure the ionizing radiation curable resin composition contained in the shaped layer by irradiating with ionizing radiation simultaneously with the shaping in step 2.

[0052] When another layer such as a primer layer is provided between the substrate layer 11 and the alignment film 20, it is preferable to carry out a step of forming the other layer on the substrate layer 11 before step 1.

[0053] Next, in step 2, a layer containing a resin is shaped using a plate having a shape complementary to the surface shape of the alignment film 20. The plate used in step 2 can be produced by a general-purpose means such as laser lithography, electron beam lithography, or FIB (Focused Ion Beam). It is also preferable to produce many plates by duplicating the plate produced by the above-mentioned means, and arrange the many duplicated plates to form a multi-faceted plate. The plate duplication can be carried out by a general-purpose means such as electroforming.

[0054] When the alignment film 20 is produced by the imprint method, the thickness of the alignment film 20 may be about 0.5 μm or more and 20 μm or less, or about 1 μm or more and 10 μm or less. Here, in the step 1 of applying the alignment film forming coating liquid, there is a possibility that foreign matter may be mixed into the alignment film forming coating liquid. Even if foreign matter is mixed into the alignment film forming coating liquid in this way, the alignment film 20 has a thickness of 0.5 μm or more, so that the foreign matter can be taken into the alignment film 20. That is, it is possible to prevent the foreign matter from being exposed from the surface of the alignment film 20. Therefore, it is possible to prevent a decrease in yield. Furthermore, since the alignment film 20 has a thickness of 0.5 μm or more, it is possible to easily produce the recesses 22 having a depth of 200 nm or less. Furthermore, since the alignment film 20 has a thickness of 20 μm or less, it is possible to prevent the occurrence of insufficient curing in the curable resin when irradiated with ultraviolet light. Therefore, it is possible to prevent the alignment film 20 from being unable to be released from the plate.

[0055] <Retardation layer> The retardation layer 30 may contain a liquid crystal compound. The retardation layer 30 may be made of a composition further containing a photopolymerization initiator, a surfactant, and a solvent. A chiral agent may be added to the composition for making the retardation layer 30, and the composition may be configured to orient the liquid crystal compound in a helical shape in the thickness direction of the retardation layer 30. Such a retardation layer 30 may be a single layer or may include multiple layers. Here, the liquid crystal compound, photopolymerization initiator, surfactant, and solvent of the retardation layer 30 will be described first.

[0056] <<Liquid crystal compounds>> The liquid crystal compound of the retardation layer 30 may be a rod-shaped liquid crystal compound such as a nematic liquid crystal compound and a smectic liquid crystal compound, or a discotic liquid crystal compound. In this embodiment, the liquid crystal compound of the retardation layer 30 may be a rod-shaped liquid crystal compound or a discotic liquid crystal compound. In addition, the liquid crystal compound may be a polymerizable liquid crystal compound. In other words, the retardation layer 30 may be a cured product of a composition containing a polymerizable liquid crystal compound.

[0057] The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group, and examples thereof include monofunctional liquid crystal compounds having one polymerizable group and polyfunctional liquid crystal compounds having two or more polymerizable groups. Among these, polyfunctional liquid crystal compounds are preferred, polyfunctional liquid crystal compounds having 2 to 3 polymerizable groups are more preferred, and polyfunctional liquid crystal compounds having 2 polymerizable groups are even more preferred. The polymerizable group is one that can be polymerized by irradiation with active energy rays such as ultraviolet rays, and examples thereof include ethylenically unsaturated double bonds such as vinyl groups, methacryloyl groups, and acryloyl groups.

[0058] In the retardation layer 30, the liquid crystal compound may be fixed in any of the alignment states of horizontal alignment, hybrid alignment, and tilt alignment. For example, the long axis of the rod-shaped liquid crystal compound may be substantially horizontal to the surface of the retardation layer 30. The rod-shaped liquid crystal compound being substantially horizontal means that the angle between the surface of the retardation layer 30 and the director of the rod-shaped liquid crystal compound is in the range of 0° to 20°. The angle may be 0° to 10°, or 0° to 5°.

[0059] The discotic liquid crystal compound may have a substantially perpendicular surface to the film surface (optically anisotropic layer surface). The discotic liquid crystal compound is substantially perpendicular to the film surface (optically anisotropic layer surface). The average angle between the surface of the retardation layer 30 and the discotic liquid crystal compound is within the range of 70° to 90°. The angle may be 80° to 90°, or 85° to 90°.

[0060] As the rod-shaped liquid crystal compound, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexane carboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, or alkenylcyclohexylbenzonitriles can be used. As the rod-shaped liquid crystal compound, not only these low molecular weight liquid crystal compounds but also polymeric liquid crystal compounds can be used. In addition, the rod-shaped liquid crystal compound may have a polymerizable group. The number of polymerizable groups in one molecule of the rod-shaped liquid crystal compound may be 2 or 3, or may be 2.

[0061] Discotic liquid crystal compounds are described in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., vol. 71, page 111 (1981); Quarterly Chemistry Review, No. 22, Chemistry of Liquid Crystals, Chapter 5, Chapter 10, Section 2 (1994), edited by the Chemical Society of Japan; B. Kohne et al., Angew. Chem. Soc. Chem. Comm., page 1794 (1985); J. Zhang et al., J. Am. Chem. Soc., vol. 116, page 2655 (1994)). Polymerization of discotic liquid crystal compounds is described in JP-A-8-27284.

[0062] The discotic liquid crystal compound may have a polymerizable group. In this case, for example, a structure in which a polymerizable group is bonded as a substituent to the discotic core of the discotic liquid crystal compound is considered. On the other hand, if the polymerizable group is directly bonded to the discotic core, it may be difficult to maintain the alignment state during the polymerization reaction. Therefore, the discotic liquid crystal compound may have a linking group between the discotic core and the polymerizable group. That is, the discotic liquid crystal compound having a polymerizable group may be a compound represented by the following formula: D(-LP)n In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 1 to 12. Specific examples of the discotic core (D), the divalent linking group (L), and the polymerizable group (P) in the formula are (D1) to (D15), (L1) to (L25), and (P1) to (P18) described in JP-A-2001-4837, respectively, and the contents described in the same publication can be used. The phase transition temperature of the discotic liquid crystal compound may be 30° C. or more and 300° C. or less, or 30° C. or more and 170° C. or less.

[0063] In addition, as described later, the retardation layer 30 may exhibit reverse dispersion. In this case, as a liquid crystal compound exhibiting reverse dispersion, compounds described in each publication such as JP-T-2010-537954, JP-T-2010-537955, JP-T-2010-522892, JP-T-2010-522893, or JP-T-2013-509458, or each patent publication such as Japanese Patent No. 5892158, Japanese Patent No. 5979136, Japanese Patent No. 5994777, or Japanese Patent No. 6015655 may be used.

[0064] The liquid crystal compound may be used alone or in combination of two or more. When using one liquid crystal compound alone, the liquid crystal compound may be a polymerizable liquid crystal compound. When using two or more liquid crystal compounds in combination, at least one may be a polymerizable liquid crystal compound, or all may be polymerizable liquid crystal compounds. The content of the polymerizable liquid crystal compound in the composition constituting the retardation layer 30 may be 60% by mass or more and 99.9% by mass or less, or 65% by mass or more and 98% by mass or less, based on the total solid matter in the composition.

[0065] <<Photopolymerization initiator>> Examples of the photopolymerization initiator of the retardation layer 30 include acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, and thioxanthones. The content of the photopolymerization initiator in the composition constituting the retardation layer 30 may be 0.01% by mass or more and 20% by mass or less, or 0.5% by mass or more and 5% by mass or less, based on the total solid matter in the composition.

[0066] <<Surfactants>> The surfactant of the retardation layer 30 may be a fluorine-based surfactant having a polymerizable group or a silicon-based surfactant having a polymerizable group. The fluorine-based surfactant and the silicon-based surfactant may be used in combination. The content of the surfactant in the composition constituting the retardation layer 30 may be 0.01% by mass or more and 2.0% by mass or less, or 0.1% by mass or more and 1.0% by mass or less, based on the total solid matter in the composition.

[0067] <<Solvent>> Examples of the solvent for the retardation layer 30 include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (butanol, cyclohexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), or amides (dimethylformamide, dimethylacetamide, etc.), and mixtures thereof may also be used. The content of the solvent in the composition constituting the retardation layer 30 may be 50% by mass or more and 90% by mass or less, or 70% by mass or more and 80% by mass or less, in the composition.

[0068] Such a retardation layer 30 can be formed, for example, by applying a composition constituting the retardation layer 30 onto the alignment film 20, and then drying and curing the composition. Specific drying conditions vary depending on the composition constituting the retardation layer 30, but the drying temperature may be 40° C. or higher and 150° C. or lower. In order to suppress deformation of the base layer 11, the drying temperature is preferably 40° C. or higher and 100° C. or lower. The drying time may be 30 seconds or higher and 250 seconds or lower, or 50 seconds or higher and 200 seconds or lower. When polymerizing the polymerizable liquid crystal compound, ultraviolet rays may be used. The irradiation energy of the ultraviolet rays varies depending on the thickness of the retardation layer 30, etc., but is preferably 50 mJ / cm. 2 More than 1J / cm 2 or less, 150 mJ / cm 2 More than 900mJ / cm 2 It may be the following.

[0069] The retardation layer 30 is most preferably a layer that gives a retardation of λ / 2 at a measurement wavelength of 550 nm, but may also be a layer that gives a retardation of n times λ / 4 (nλ / 4). The retardation layer 30 may be a λ / 2 retardation layer or a λ / 4 retardation layer. When the retardation layer 30 is a λ / 2 retardation layer, the in-plane retardation at a wavelength of 550 nm may be 220 nm or more and 300 nm or less, 230 nm or more and 280 nm or less, or 240 nm or more and 275 nm or less. When the retardation layer 30 is a λ / 4 retardation layer, the in-plane retardation at a wavelength of 550 nm may be 90 nm or more and 160 nm or less, 100 nm or more and 150 nm or less, or 110 nm or more and 150 nm or less. In this specification, the in-plane phase difference (in-plane retardation, Re) can be expressed by the following formula, where the refractive index in the in-plane slow axis direction is nx, the refractive index in the in-plane direction perpendicular to nx is ny, the refractive index in the direction perpendicular to nx and ny is nz, and the film thickness is d (nm). In-plane phase difference (Re)=(nx-ny)×d The in-plane retardation of the retardation layer 30 means the average value of five in-plane retardations excluding the maximum value and the minimum value from the in-plane retardations at seven locations in the plane of the retardation layer 30. The wavelength λ of the light serving as the reference for the retardation is 550 nm. As a measuring device for the in-plane retardation, the product name "AxoStep" manufactured by AXOMETRICS can be mentioned.

[0070] The retardation layer 30 may exhibit positive dispersion or negative dispersion. Note that negative dispersion is a characteristic in which the retardation imparted to the transmitted light increases as the wavelength of the transmitted light becomes longer. Specifically, negative dispersion is a characteristic in which the relationship between the retardation (Re450) at a wavelength of 450 nm and the retardation (Re550) at a wavelength of 550 nm is Re450 < Re550. On the other hand, positive dispersion is a characteristic in which the relationship between Re450 and Re550 is Re450 > Re550.

[0071] The thickness of the retardation layer 30 can be appropriately adjusted within the range of 0.1 μm or more and 10 μm or less in consideration of the retardation to be imparted.

[0072] The optical film 10 according to the present embodiment may further include a functional layer, an adhesive layer, or the like as other layers.

[0073] <Functional layer> The functional layer may have functions such as a hard coat layer, an antiglare layer, or an antireflection layer. The functional layer may be formed, for example, on the base material layer 11 or the like.

[0074] <Adhesive layer> The adhesive layer may be a layer for adhering the respective layers of the optical film 10 to each other. As the adhesive constituting the adhesive layer, general-purpose adhesives such as acrylic adhesives, polyester adhesives, urethane adhesives, or vinyl adhesives may be used. The adhesive layer formed from these general-purpose adhesives usually has optical isotropy. The thickness of the adhesive layer may be about 2 μm or more and 30 μm or less.

[0075] <Specific layer configuration of the optical film> The layer structure of the optical film 10 is not particularly limited, but the optical film 10 may have the following structures (1) to (15), where " / " indicates the interface between layers. (1) Base layer / Alignment film / Retardation layer (2) Functional layer / base layer / alignment film / retardation layer (3) Base layer / adhesive layer / retardation layer / alignment film / base layer (4) Base layer / adhesive layer / retardation layer / alignment film / base layer / functional layer (5) Functional layer / base layer / adhesive layer / retardation layer / alignment film / base layer (6) Functional layer / base layer / adhesive layer / retardation layer / alignment film / base layer / functional layer (7) Base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer (8) Base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer / functional layer (9) Functional layer / base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer (10) Base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer (11) Base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer / functional layer (12) Functional layer / base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer

[0076] Next, the polarizing plate 40 and the display device 50 of the image display device 1 will be described.

[0077] [Polarizing plate] The polarizing plate plays a role of exerting a light absorbing performance or an anti-reflection performance by being disposed on a display element such as an organic EL element or a touch panel such as a resistive film type touch panel (not shown). The polarizing plate may be a linear polarizing plate or a circular polarizing plate.

[0078] The polarizer of the polarizing plate may be an iodine-based polarizer, a dye-based polarizer using a dichroic dye, or a polyene-based polarizer. Iodine-based polarizers and dye-based polarizers can generally be manufactured using a polyvinyl alcohol-based film. The absorption axis of the polarizer corresponds to the stretching direction of the film. Therefore, a polarizer stretched in the vertical direction (transport direction) has an absorption axis extending parallel to the longitudinal direction. On the other hand, a polarizer stretched in the horizontal direction (direction perpendicular to the transport direction) has an absorption axis extending perpendicular to the longitudinal direction.

[0079] [Display device] The display device 50 is, for example, an organic EL (Electro Luminescence) display device. The display device 50 may include, for example, a metal layer, a support substrate, a resin substrate, a thin film transistor (TFT), and an organic EL layer, all of which are not shown. A touch panel, not shown, may be disposed on the display device 50. The touch panel may be a resistive touch panel, a capacitive touch panel, an optical touch panel, an ultrasonic touch panel, an electromagnetic induction touch panel, or the like. These touch panels may have a pressure detection function. Although not shown, the display device 50 may be housed in a housing, not shown, together with a control unit (not shown) electrically connected to the display device 50.

[0080] Next, a method for producing the optical film 10 according to the present embodiment will be described.

[0081] First, the base layer 11 is prepared.

[0082] Next, an alignment film 20 is formed on the base material layer 11. In this case, first, for example, a UV curable resin is applied onto the base material layer 11, and then the unevenness 21 is formed by, for example, an imprint method. Thereafter, the UV curable resin is irradiated with ultraviolet rays to cure the UV curable resin.

[0083] Next, the retardation layer 30 is formed on the alignment film 20. In this case, for example, a composition constituting the retardation layer 30 is applied onto the alignment film 20, and then the composition is dried and cured to form the retardation layer 30.

[0084] In this manner, the optical film 10 shown in FIG. 4 is obtained.

[0085] As described above, according to this embodiment, the area of ​​each pattern region 25 is 0.015 μm 2 More than 10μm 2 In this way, when the area of ​​the pattern region 25 is 0.015 μm 2 By satisfying the above conditions, the shape of the irregularities 21 can be improved when the alignment film 20 is produced by an imprint method. 2 By satisfying the condition below, even if the longitudinal direction of the recesses 22 of the unevenness 21 is changed stepwise, it is possible to prevent the formation of a portion where the liquid crystal compound is sparsely arranged, thereby improving the alignment of the liquid crystal compound.

[0086] Moreover, according to the present embodiment, when each pattern region 25 is equally divided into six parts (first part 25a to sixth part 25f) along the first direction X, the minimum value of the ratio of the area of ​​the recesses 22 of the irregularities 21 to the area of ​​the part in each part is 90% or more and 99.5% or less of the maximum value of the ratio. In this way, since the minimum value of the ratio in the six parts is 90% or more of the maximum value of the ratio in the six parts, it is possible to suppress the formation of a part in which the liquid crystal compound is sparsely arranged in the pattern region 25. Therefore, the alignment of the liquid crystal compound can be improved. Furthermore, since the minimum value of the ratio in the six parts is 99.5% or less of the maximum value of the ratio in the six parts, it is possible to reduce the difference in the ratio in the six parts. This makes it possible to suppress the liquid crystal compound in a predetermined part from affecting the alignment direction of the liquid crystal compound in an adjacent part. Therefore, it is possible to suppress the occurrence of abnormalities in the alignment direction of the liquid crystal compound. As a result, it is possible to improve the alignment of the liquid crystal compound.

[0087] Moreover, according to the present embodiment, the ratio of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the pattern region 25 in one pattern region 25 among the adjacent pattern regions 25 is 90% or more and 110% or less of the ratio of the area of ​​the recesses 22 of the unevenness 21 to the area of ​​the pattern region 25 in the other pattern region 25. In this way, since the ratio in one pattern region 25 is 90% or more of the ratio in the other pattern region 25, poor alignment of the liquid crystal compound between the pattern regions 25 can be suppressed. Furthermore, since the ratio in one pattern region 25 is 110% or less of the ratio in the other pattern region 25, the difference in the ratio between the pattern regions 25 can be reduced. This can suppress the liquid crystal compound in a given pattern region 25 from affecting the alignment direction of the liquid crystal compound in the adjacent pattern region 25. Therefore, it is possible to suppress the occurrence of abnormalities in the alignment direction of the liquid crystal compound. As a result, the alignment property of the liquid crystal compound can be improved.

[0088] Furthermore, according to the present embodiment, a gap G is provided between the pattern regions 25. This makes it possible to suppress the formation of portions where the liquid crystal compound is sparsely arranged, while allowing the longitudinal direction of the unevenness 21 to change stepwise. This makes it possible to further improve the alignment of the liquid crystal compound.

[0089] In the above-described embodiment, the shape of the pattern region 25 is a square in a plan view, but is not limited thereto. For example, as shown in FIG. 7, the shape of the pattern region 25 may be an L-shape in a plan view.

[0090] 8 and 9, the alignment film 20 may include a plurality of pattern regions 25 having different shapes. In the example shown in FIG. 8, the alignment film 20 includes a pattern region 25D that is a rectangle whose long sides extend along the first direction X, a pattern region 25E that is a square, and a pattern region 25F that is a rectangle whose long sides extend along the second direction Y in a plan view. In the example shown in FIG. 9, the alignment film 20 includes a pattern region 25D that is a rectangle whose long sides extend along the first direction X, a pattern region 25G that is a parallelogram whose pair of sides extend along the second direction Y, and a pattern region 25F that is a rectangle whose long sides extend along the second direction Y in a plan view. In these cases, in each pattern region 25, the longitudinal direction of the recess 22 preferably extends along the longitudinal direction of the pattern region 25 or along the diagonal of the planar shape of the pattern region 25. This allows the length of the recess 22 to be increased, and the alignment of the liquid crystal compound to be improved.

[0091] 10, the pattern region 25 may extend along the direction in which the irregularities 21 extend. In this case, the alignment film 20 includes a pattern region 25H having a first region 26, a second region 27, and a third region 28, and a pattern region 25J that is a rectangle with its long sides extending along the second direction Y. Among these, the first region 26 and the third region 28 of the pattern region 25H are parallelograms with a pair of sides extending along the second direction Y. The second region 27 of the pattern region 25H is a rectangle with its long sides extending along the first direction X. In this case, the length of the recesses 22 can be made longer in each pattern region 25, and the alignment of the liquid crystal compound can be improved.

[0092] 11, when the pattern region 25 extends along the direction in which the unevenness 21 extends, the outer edge of the pattern region 25 may extend in a curved (arcuate) shape along the direction in which the unevenness 21 extends. Even in this case, the length of the recesses 22 can be made longer in each pattern region 25. Furthermore, in this modification, the formation of short recesses 22 in each pattern region 25 can be effectively prevented. Therefore, the average length of the recesses 22 can be made longer, and the alignment of the liquid crystal compound can be further improved.

[0093] It is also possible to combine the multiple components disclosed in the above embodiment and each modification as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiment and each modification.

Claims

1. An alignment film, A plurality of pattern areas are provided, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, The area of ​​each of the pattern regions is 0.015 μm ２ 10 μm or more ２ Below is the alignment film.

2. An alignment film, A plurality of pattern areas are arranged along a first direction, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, An alignment film, wherein when each of the pattern regions is divided into six equal parts along the first direction, the minimum ratio of the area of ​​the concave parts of the unevenness to the area of ​​the part in each of the parts is 90% or more and 99.5% or less of the maximum ratio.

3. An alignment film, A plurality of pattern areas are provided, Each of the pattern regions has a plurality of projections and recesses, In the pattern regions adjacent to each other, the longitudinal directions of the projections and recesses are different from each other, An alignment film, wherein the ratio of the area of ​​the concave portions of the unevenness to the area of ​​the pattern region in one of the adjacent pattern regions is 90% or more and 110% or less of the ratio of the area of ​​the concave portions of the unevenness to the area of ​​the pattern region in the other pattern region.

4. The alignment film according to claim 1 , wherein a gap is provided between the pattern regions.

5. The alignment film according to claim 1 , wherein the pattern region extends in a direction in which the projections and recesses extend.

6. The pattern regions are arranged along a first direction, A length of the pattern area along the first direction is L1, In the pattern region, when the length of the longest recess is L2, L1≦L2 The alignment film according to claim 1 , which satisfies the following relationship:

7. A base layer; The alignment film according to claim 1 , which is laminated on the base layer; A retardation layer is laminated on the alignment film, The optical film, wherein the base layer, the alignment film, and the retardation layer are laminated in this order.

8. The optical film according to claim 7 ; and a display device laminated on the optical film.

9. The image display device according to claim 8 , further comprising a polarizing plate disposed between the optical film and the display device, or on the opposite side of the optical film to the display device.

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