Optical film and image display device

Abstract

To provide an optical film with which it is possible to improve the design quality of a displayed image.SOLUTION: A retardation layer 30 of the optical film contains a cholesteric liquid crystal compound. The retardation layer 30 includes a first pattern region 31a, and a second pattern region 31b located adjacent to the first pattern region 31a in a first direction X. The first pattern region 31a has a plurality of first optical axis pattern regions Pa1 mutually differing in the direction of a slow axis. The plurality of first optical axis pattern regions Pa1 are arranged along the first direction X. The second pattern region 31b has a plurality of second optical axis pattern regions Pa2 mutually differing in the direction of the slow axis. The plurality of second optical axis pattern regions Pa2 are arranged along the first direction X. A width W1 of the first pattern region 31a is 80% or less of a width W2 of the second pattern region 31b.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-536100 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in such image display devices, there is a demand for improving the design of the images to be displayed.

[0006] The present disclosure has been made in consideration of the above points, and has an object to provide an optical film and an image display device that are capable of improving design properties. [Means for solving the problem]

[0007] The embodiments of the present disclosure relate to the following [1] to

[10] .

[0008] [1] An optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, The retardation layer has a first pattern region and a second pattern region arranged adjacent to the first pattern region in a first direction, The first pattern region has a plurality of first optical axis pattern regions whose slow axis directions are different from each other, The first optical axis pattern regions are arranged along the first direction, The second pattern region has a plurality of second optical axis pattern regions whose slow axis directions are different from each other, The second optical axis pattern regions are arranged along the first direction, An optical film, wherein the width of the first pattern region is 80% or less of the width of the second pattern region.

[0009] [2] The optical film according to [1], wherein the width of the first pattern region and the width of the second pattern region are 20 μm or less.

[0010] [3] An optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, The retardation layer has a first pattern region and a second pattern region arranged adjacent to the first pattern region in a first direction, The first pattern region has a plurality of first optical axis pattern regions whose slow axis directions are different from each other, The first optical axis pattern regions are arranged along the first direction, The second pattern region has a plurality of second optical axis pattern regions whose slow axis directions are different from each other, The optical film, wherein the second optical axis pattern regions are arranged along a second direction different from the first direction.

[0011] [4] The optical film according to [3], wherein the width of the first pattern region is 80% or less of the width of the second pattern region.

[0012] [5] The optical film according to [3] or [4], wherein the width of the first pattern region and the width of the second pattern region are 20 μm or less.

[0013] [6] An optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, the retardation layer has a pattern region in which the cholesteric liquid crystal compound is arranged in a predetermined pattern, and a solid region in which the cholesteric liquid crystal compound is not arranged in a predetermined pattern, The optical film, wherein the pattern region includes a plurality of optical axis pattern regions having slow axis directions different from each other.

[0014] [7] The optical film according to [6], wherein the width of the pattern region is 20 μm or less.

[0015] [8] A base layer; An alignment film laminated on the base layer, The optical film according to any one of [1] to [7], wherein the base layer, the alignment film, and the retardation layer are laminated in this order.

[0016] [9] The alignment film contains a UV curable resin, The optical film according to [8], wherein the alignment film has projections and recesses corresponding to the slow axis.

[0017]

[10] [1] to [9], and and a display device laminated on the optical film. Effect of the Invention

[0018] According to the embodiments of the present disclosure, the design of a displayed image 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 layer of an optical film according to an embodiment. [Figure 6] FIG. 6 is a cross-sectional view (a cross-sectional view taken along line VI-VI in FIG. 5) showing an alignment layer of an optical film according to an embodiment. [Figure 7A] FIG. 7A is a plan view illustrating another example of an alignment layer of an optical film according to an embodiment. [Figure 7B] FIG. 7B is a plan view illustrating another example of the alignment layer of the optical film according to the embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an exposure apparatus for producing an alignment film. [Figure 9] FIG. 9 is a cross-sectional view showing an optical film according to an embodiment. [Figure 10] FIG. 10 is a plan view showing a retardation layer of an optical film according to an embodiment. [Figure 11A] FIG. 11A is a plan view showing another example of a retardation layer of an optical film according to an embodiment. [Figure 11B] FIG. 11B is a plan view showing another example of the retardation layer of the optical film according to the embodiment. [Figure 12A] FIG. 12A is a plan view showing another example of a retardation layer of an optical film according to an embodiment. [Figure 12B] FIG. 12B is a plan view showing another example of the retardation layer of the optical film according to the embodiment. [Figure 12C]FIG. 12C is a plan view showing another example of the retardation layer of the optical film according to the embodiment. [Figure 13] FIG. 13 is a plan view showing another example of the retardation layer of the optical 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 strict meanings, but are to be interpreted to include a 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 retardation layer 30. The optical film 10 may further include a base layer 11 and an alignment film 20 laminated on the base layer 11. 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 plays a role in facilitating alignment of the liquid crystal compound in the retardation layer 30 when the retardation layer 30 is formed. After the retardation layer 30 is formed, the alignment film 20 may be removed. This makes it possible to obtain an optical film 10 without the alignment film 20.

[0030] As shown in FIG. 5 and FIG. 6, the alignment film 20 may have a concave-convex shape 21 corresponding to the slow axis of the optical axis pattern region Pa of the retardation layer 30, which will be described later. 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 concave-convex shape 21. For example, when it is desired to change the direction of the in-plane slow axis for each optical axis pattern region Pa of the retardation layer 30, which will be described later, the alignment direction of the liquid crystal compound is changed by changing the longitudinal direction of the concaves 22 for each optical axis pattern region Pa. This allows the direction of the in-plane slow axis to be changed for each optical axis pattern region Pa. In this case, for example, the concave-convex shape 21 may be formed by an imprint method.

[0031] In the example shown in FIG. 5, the recesses 22 of the unevenness 21 extend linearly. The recesses 22 extend in a direction inclined in the first direction X and in a direction inclined in the second direction Y perpendicular to the first direction X. However, this is not limited thereto, and for example, as shown in FIG. 7A and FIG. 7B, the recesses 22 of the unevenness 21 may extend in a curved shape (for example, an arc shape). The first direction X and the second direction Y are directions perpendicular to the lamination direction Z of the optical film 10. Also, FIG. 5 and FIG. 7A show the alignment film 20 in the case where the number of optical axis pattern regions Pa described later in the retardation layer 30 is two, and FIG. 7B shows the alignment film 20 in the case where the number of optical axis pattern regions Pa described later in the retardation layer 30 is four.

[0032] 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.

[0033] The means for imparting an alignment regulating force to the alignment film 20 may be a conventionally known means. For example, the means for imparting an alignment regulating force to the alignment film 20 may be an imprinting method, a rubbing method, or a photoalignment method. Although any method can be used for fabrication, the imprinting method is preferred because roll processing can be efficiently performed when the shape is not linear. When fabricating the alignment film 20 by the imprinting method, it is preferred to use an electron beam curable resin in order to prevent deformation of the shape after curing. In addition, when fabricating the alignment film 20 by the imprinting method, 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 UV curable resins include materials obtained by adding a photopolymerization initiator and any additive to a single material or a mixture of a polymerizable oligomer or monomer having an acryloyl group, such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, and melamine acrylate, and a polymerizable oligomer or monomer having a polymerizable vinyl group, such as acrylic acid, acrylamide, acrylonitrile, and styrene. The material of the alignment film 20 may be, for example, a thermosetting resin. When the alignment film 20 is produced by the photo-alignment method, first, a solution containing a thermosetting resin is dried to remove the solvent. Then, a mask having a shape corresponding to the irregularities 21 of the present embodiment is used to perform intermolecular dimerization or isomerization by irradiating ultraviolet light through the mask, thereby producing the alignment film 20 having a desired shape.

[0034] <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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] <Photo-alignment method> Next, a method for producing the alignment film 20 by a photo-alignment method will be described. Methods for producing the alignment film 20 by a photo-alignment method include a method using two-beam interference and a method of irradiating linearly polarized light using a light-shielding mask.

[0043] In the method using two-beam interference, first, a liquid in which a birefringence-inducing polymer is dissolved in a solvent is applied onto the base layer 11. Next, the liquid is dried to produce a coating film. Next, an orientation control force is imparted to the coating film by two-beam interference using highly coherent polarized beams such as laser beams.

[0044] The following two methods can be mentioned as a method using a light-shielding mask. In the first method, a light-shielding mask having a desired periodic pitch is used at least twice to irradiate at least two regions with linearly polarized light having different polarization characteristics and intensity. In the second method, first, a light-shielding mask having a desired periodic pitch is used to irradiate linearly polarized light. Next, linearly polarized light is irradiated without using a light-shielding mask to form regions with different irradiation energy amounts at a desired periodic pitch. This gives a periodic structure in which the molecular orientation directions differ by 90°. When comparing the first method with the second method, the second method has the advantage of being able to simplify the device.

[0045] Examples of photo-alignment materials used in the alignment film 20 according to the present embodiment include those described in JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, JP-A-2007-121721, JP-A-2007-140465, and JP-A-2007-156439. azo compounds described in JP-A-2007-133184, JP-A-2009-109831, JP-A-3883848 and JP-A-4151746, aromatic ester compounds described in JP-A-2002-229039, and compounds having photoalignment units described in JP-A-2002-265541 and JP-A-2002-317013. photocrosslinkable polyimides, photocrosslinkable polyamides, and photocrosslinkable polyesters described in JP-T-2003-520878, JP-T-2004-529220, and JP-T-4162850; and photodimerizable compounds, particularly cinnamate compounds, chalcone compounds, and coumarin compounds, described in JP-A-9-118717, JP-T-10-506420, JP-T-2003-505561, WO 2010 / 150748, JP-A-2013-177561, and JP-A-2014-12823. Among these, photocrosslinkable polyimides, photocrosslinkable polyamides, photocrosslinkable polyesters, cinnamate compounds and chalcone compounds are preferred.

[0046] Next, an exposure device 70 for imparting an alignment regulating force to the alignment film 20 by a photo-alignment method will be described.

[0047] 8, the exposure device 70 includes a light source 71, a polarizing beam splitter 72, mirrors 73A and 73B, and λ / 4 plates 74A and 74B. Among these, the light source 71 includes a laser irradiation unit 75 and a λ / 2 plate (not shown). The light source 71 is configured to emit linearly polarized light P0 by changing the polarization direction of the laser light M emitted from the laser irradiation unit 75.

[0048] The polarizing beam splitter 72 serves to split the laser light M emitted from the light source 71 into two beams MA and MB.

[0049] The mirrors 73A and 73B are disposed on the optical paths of the two separated light beams MA and MB, respectively.

[0050] The λ / 4 plates 74A and 74B have parallel optical axes. The λ / 4 plate 74A converts the linearly polarized light P0 (light beam MA) into right-handed circularly polarized light P R The λ / 4 plate 74B converts the linearly polarized light P0 (light beam MB) into left-handed circularly polarized light P L It plays a role in converting

[0051] In such an exposure device 70, the alignment film 20a before the alignment pattern is formed is placed in an exposure section (not shown). Then, two light beams MA and MB are made to intersect on the alignment film 20a to cause interference. Due to this interference, the polarization state of the interference light periodically changes to an interference fringe pattern. Next, the alignment film 20a is exposed by being irradiated with the interference light. As a result, an alignment pattern in which the alignment state periodically changes is obtained in the alignment film 20.

[0052] In the exposure device 70, the period of the alignment pattern can be adjusted by changing the crossing angle α of the two light beams MA and MB. For example, when forming an alignment pattern on the alignment film 20 in which the slow axis of the liquid crystal compound rotates continuously by 180° in one direction, the length of one period in which the slow axis rotates by 180° can be adjusted by adjusting the crossing angle α. By forming a cholesteric liquid crystal layer on the alignment film 20 having such an alignment pattern, it is possible to form a retardation layer 30 in which the slow axis of the liquid crystal compound rotates continuously in one direction. In addition, the rotation direction of the optical axis can be reversed by rotating the optical axes of the λ / 4 plates 74A and 74B by 90°, respectively.

[0053] When the alignment film 20 is produced by a photoalignment method, the thickness of the alignment film 20 may be about 1 nm or more and 1000 nm or less, or about 60 nm or more and 300 nm or less. When the thickness of the alignment film 20 is 1 nm or more, foreign matter can be taken into the alignment film 20, and a decrease in yield can be suppressed. Furthermore, when the thickness of the alignment film 20 is 1000 nm or less, a deterioration in the sensitivity of the alignment film 20 due to polarized light exposure can be suppressed. Therefore, a decrease in the liquid crystal alignment control force can be suppressed.

[0054] The alignment film 20 may be produced by a roll-to-roll method. By producing the alignment film 20 by the roll-to-roll method, the alignment film 20 can be mass-produced in a short time. The alignment film 20 may be produced from a single sheet. When producing the alignment film 20 from a sheet, the alignment film 20 can be produced from a metal plate or a resin plate by an imprint method, and can be produced by using an exposure mask by a photoalignment method.

[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. Here, the liquid crystal compound, the photopolymerization initiator, the surfactant, and the 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 cholesteric liquid crystal compound. When the retardation layer 30 contains a cholesteric liquid crystal compound, the retardation layer 30 has a helical structure in which the cholesteric liquid crystal compound 35 (see FIG. 9) is spirally wound and stacked. In this case, the retardation layer 30 may have a structure in which a plurality of layers of the compound in which the cholesteric liquid crystal compound 35 is spirally wound (rotated 360°) are stacked.

[0057] The retardation layer 30 has a characteristic of reflecting light of a specific wavelength. For example, when reflecting green light, the retardation layer 30 reflects right-handed circularly polarized light of green light and transmits other light. Such a retardation layer 30 is oriented in the plane direction so that the cholesteric liquid crystal compound 35 rotates. Therefore, the incident circularly polarized light is refracted (diffracted) in a direction in which the optical axis direction is continuously rotating, and reflected. At this time, the direction in which the circularly polarized light is diffracted differs depending on the rotation direction of the incident circularly polarized light. That is, the retardation layer 30 plays a role of reflecting right-handed or left-handed circularly polarized light of a specific wavelength and diffracting the reflected light.

[0058] When the alignment film 20 shown in FIG. 7A and FIG. 7B is used as the alignment film 20 described above, the molecular axis of the cholesteric liquid crystal compound 35 in the retardation layer 30 is inclined with respect to the surface 11a of the base layer 11 as shown in FIG. 9. In this case, the reflection surface Ref of the retardation layer 30 is inclined at a predetermined angle with respect to the surface 11a of the base layer 11. In this embodiment, the inclination angle θ of the reflection surface Ref with respect to the surface 11a of the base layer 11 increases as the width of the pattern region 31 described later decreases. Here, the reflection surface Ref of the retardation layer 30 is a plane on which liquid crystal compounds having the same azimuth angle exist. In addition, the "liquid crystal compounds having the same azimuth angle" refers to liquid crystal compounds having substantially the same alignment direction of the molecular axis 36 when projected onto the surface 11a of the base layer 11.

[0059] 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.

[0060] 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.

[0061] In the retardation layer 30, the liquid crystal compound may be fixed in an inclined alignment state. In this case, the above-mentioned inclination angle θ may be 1° or more and 60° or less, or 1° or more and 45° or less. In general, when the inclination angle θ is 60° or more, light is totally reflected at the reflection surface Ref. For this reason, the inclination angle θ is preferably 60° or less. In addition, although it depends on the distance between the optical film 10 and the observer, it is preferable that the reflection surface Ref is inclined even slightly with respect to the surface 11a of the base layer 11, because this distinguishes between coloring due to reflection of the cholesteric liquid crystal compound and coloring due to diffraction.

[0062] 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.

[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 2or 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...Equation (1) Here, when nx-ny=Δn (in-plane birefringence), Δn is practically difficult to measure. Therefore, Δn is calculated from the in-plane retardation (Re) and film thickness d using the above formula (1). In this case, the in-plane retardation (Re) is measured using the following "AxoStep." The film thickness d of the retardation layer 30 is measured by cutting the optical film 10 using a microtome, and then measuring the cross-section with a SEM. In this way, it is possible to easily calculate Δn using the above formula (1). The in-plane retardation of the retardation layer 30 means an average value of five in-plane retardations excluding the maximum and minimum values ​​from among seven in-plane retardations in the plane of the retardation layer 30. The wavelength λ of light serving as a reference for the retardation is 550 nm. An example of a measuring device for the in-plane retardation is "AxoStep" manufactured by AXOMETRICS.

[0070] The retardation layer 30 may exhibit positive dispersion or negative dispersion. Note that negative dispersion is a characteristic in which the phase difference 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 phase difference to be imparted.

[0072] Here, as shown in FIG. 10, in the present embodiment, the retardation layer 30 has a plurality of pattern regions 31. In the illustrated example, the retardation layer 30 has a first pattern region 31a and a second pattern region 31b disposed adjacent to the first pattern region 31a in the first direction X. Further, in the illustrated example, the retardation layer 30 further has a third pattern region 31c disposed adjacent to the second pattern region 31b in the first direction X. Note that the number of pattern regions 31 included in the retardation layer 30 may be 3 or more and 90 or less. Also, the pattern regions 31 of the retardation layer 30 may be arranged in a plurality along a curve (for example, a meandering curve). In this case, it is possible to suppress deterioration in visibility due to diffracted light caused by reflection in one direction.

[0073] Each pattern region 31 has a plurality of optical axis pattern regions Pa whose slow axis directions are different from each other. For example, the first pattern region 31a has a plurality of first optical axis pattern regions Pa1 (Pa11, Pa12) whose slow axis directions are different from each other. The plurality of first optical axis pattern regions Pa1 are arranged along the first direction X. In the illustrated example, the first pattern region 31a has two first optical axis pattern regions Pa1. The widths of the first optical axis pattern regions Pa1 are equal to each other. The first pattern region 31a may have a plurality of first optical axis pattern regions Pa1 whose widths are close to each other. For example, the first pattern region 31a may have a first optical axis pattern region Pa1 whose width is 5 μm (median value) and a first optical axis pattern region Pa1 whose width is 4 μm or 6 μm. In addition, the straight lines in the first optical axis pattern region Pa1 in FIG. 10, the second optical axis pattern region Pa2 described later, and the third optical axis pattern region Pa3 described later indicate the direction of the slow axis in the plane. In addition, the curves in the first optical axis pattern region Pa1 in FIG. 11A and FIG. 11B described later, the second optical axis pattern region Pa2 described later, and the third optical axis pattern region Pa3 described later indicate the direction in which the liquid crystal compounds are arranged. In addition, the direction of the slow axis in the plane and the direction in which the liquid crystal compounds are arranged are not limited to these. In addition, in the first optical axis pattern region Pa1, etc., the angle γ (see FIG. 10) formed by the slow axis in the plane is preferably an obtuse angle. Thereby, for example, alignment defects near the boundary between the first optical axis pattern regions Pa1 can be effectively suppressed.

[0074] In addition, as shown in FIG. 7A and FIG. 7B, when the direction in which the unevenness 21 of the alignment film 20 extends changes continuously, the direction in which the optical axis extends changes continuously as shown in FIG. 11A and FIG. 11B. In addition, FIG. 11A shows a retardation layer 30 formed on the alignment film 20 shown in FIG. 7A, and in the retardation layer 30 shown in FIG. 11A, each pattern region 31 has two optical axis pattern regions Pa. FIG. 11B shows a retardation layer 30 formed on the alignment film 20 shown in FIG. 7B, and in the retardation layer 30 shown in FIG. 11B, each pattern region 31 has four optical axis pattern regions Pa. In these cases, depending on the width of the first optical axis pattern region Pa1, when the width of each first optical axis pattern region Pa1 is 5 μm or more, the number of first optical axis pattern regions Pa1 in the first pattern region 31a may be 3 or more and 90 or less as follows. In this case, the number of the first optical axis pattern regions Pa1 in the first pattern region 31a is preferably 10 to 60, more preferably 20 to 30. By having the number of the first optical axis pattern regions Pa1 in the first pattern region 31a be 3 or more, a sudden change in the direction in which the optical axis extends can be suppressed. Therefore, the deterioration of the liquid crystal alignment can be suppressed. In addition, by having the number of the first optical axis pattern regions Pa1 in the first pattern region 31a be 90 or less, it is possible to suppress the number of boundary portions between adjacent first optical axis pattern regions Pa1 from increasing too much. Therefore, it is possible to suppress the generation of unnecessary diffracted light at the boundary portions. When the width of each first optical axis pattern region Pa1 is 5 μm or less, there is no problem when the alignment film 20 is produced by a photo-alignment method, but when the alignment film 20 is produced by an imprint method, the number of first optical axis pattern regions Pa1 in the first pattern region 31a is preferably 3 to 20. By having the number of first optical axis pattern regions Pa1 in the first pattern region 31a be 20 or less, the width of the uneven shape of the alignment film 20 can be prevented from becoming too narrow. Therefore, the resin constituting the unevenness 21 of the alignment film 20 can maintain the shape of the convex portions in a good condition.

[0075] The second pattern region 31b has a plurality of second optical axis pattern regions Pa2 (Pa21, Pa22) whose slow axis directions are different from each other. The plurality of second optical axis pattern regions Pa2 are arranged along the first direction X. In the illustrated example, the second pattern region 31b has two second optical axis pattern regions Pa2. The number of the second optical axis pattern regions Pa2 in the second pattern region 31b may be 3 or more and 90 or less, preferably 10 or more and 60 or less, and more preferably 20 or more and 30 or less. By having the number of the second optical axis pattern regions Pa2 in the second pattern region 31b be 3 or more, it is possible to suppress the deterioration of the liquid crystal alignment. In addition, by having the number of the second optical axis pattern regions Pa2 in the second pattern region 31b be 90 or less, it is possible to suppress the boundary portions between the adjacent second optical axis pattern regions Pa2 from becoming too many. Therefore, it is possible to suppress the generation of unnecessary diffracted light at the boundary portions. Other configurations of the second pattern region 31b may be the same as those of the first pattern region 31a described above.

[0076] The third pattern region 31c has a plurality of third optical axis pattern regions Pa3 (Pa31, Pa32) whose slow axis directions are different from each other. The plurality of third optical axis pattern regions Pa3 are arranged along the first direction X. In the illustrated example, the third pattern region 31c has two third optical axis pattern regions Pa3. The number of the third optical axis pattern regions Pa3 in the third pattern region 31c may be 3 or more and 90 or less, preferably 10 or more and 60 or less, and more preferably 20 or more and 30 or less. By having the number of the third optical axis pattern regions Pa3 in the third pattern region 31c be 3 or more, it is possible to suppress the deterioration of the liquid crystal alignment. In addition, by having the number of the third optical axis pattern regions Pa3 in the third pattern region 31c be 90 or less, it is possible to suppress the boundary portions between the adjacent third optical axis pattern regions Pa3 from becoming too many. Therefore, it is possible to suppress the generation of unnecessary diffracted light at the boundary portions. Other configurations of the third pattern region 31c may be the same as those of the above-mentioned first pattern region 31a.

[0077] In the illustrated example, the directions of the slow axes of the first optical axis pattern regions Pa11, Pa12, the second optical axis pattern regions Pa21, Pa22, and the third optical axis pattern regions Pa31, Pa32 are different from each other. On the other hand, the directions of the slow axes of the first optical axis pattern regions Pa11, Pa12, the second optical axis pattern regions Pa21, Pa22, and the third optical axis pattern regions Pa31, Pa32 are the same as each other. The direction of the slow axis corresponds to the longitudinal direction of the recesses 22 of the unevenness 21 formed in the above-mentioned alignment film 20. In this specification, the first optical axis pattern regions Pa11, Pa12, the second optical axis pattern regions Pa21, Pa22, and the third optical axis pattern regions Pa31, Pa32 are collectively referred to simply as the optical axis pattern regions Pa.

[0078] In addition, when the number of optical axis pattern regions in each pattern region 31 is three or more, each optical axis pattern region Pa may be configured so that the direction of the slow axis in the plane changes stepwise along the first direction X. For example, when the number of first optical axis pattern regions Pa1 in the first pattern region 31a is three or more, each first optical axis pattern region Pa1 may be configured so that the direction of the slow axis in the plane changes stepwise along the first direction X. In this case, for example, although not shown, the angle of the slow axis in the plane of the first optical axis pattern region Pa1 with respect to the second direction Y may change stepwise as it moves toward the positive side of the first direction X. For example, when the number of first optical axis pattern regions Pa1 in the first pattern region 31a is 180, the angle of the slow axis in each first optical axis pattern region Pa1 with respect to the second direction Y may change stepwise by 1°. By gradually changing the direction of the slow axis, it is possible to suppress poor alignment of the liquid crystal compound between the first optical axis pattern regions Pa1, which is preferable. The second pattern region 31b and the third pattern region 31c may also be configured in the same way.

[0079] The shape of each optical axis pattern region Pa may be, for example, a quadrilateral such as a square, a rectangle, or a diamond, or a polygon such as a triangle or a hexagon. The width (length in the first direction X) of each optical axis pattern region Pa may be, for example, 0.001 mm or more and 1 mm or less. The widths of each optical axis pattern region Pa may be the same as each other or may be different from each other.

[0080] In this embodiment, the width W1 of the first pattern region 31a is smaller than the width W2 of the second pattern region 31b. In this case, the width W1 of the first pattern region 31a may be 80% or less of the width W2 of the second pattern region 31b. This increases the difference between the pitch of the cholesteric liquid crystal compound 35 in the first pattern region 31a and the pitch of the cholesteric liquid crystal compound 35 in the second pattern region 31b in the width direction (X direction) of the first pattern region 31a, etc. This increases the amount of change in color between the first pattern region 31a and the second pattern region 31b. In addition, in this case, for example, the difference between the inclination angle θ of the reflection surface Ref (see FIG. 9) in the first pattern region 31a and the inclination angle θ of the reflection surface Ref in the second pattern region 31b increases. This increases the amount of change in color between the first pattern region 31a and the second pattern region 31b. As a result, the visibility of the first pattern region 31a and the visibility of the second pattern region 31b can be made different, and the design (for example, designability or authenticity) of the image displayed using the optical film 10 can be improved. In addition, as shown in FIG. 7A and FIG. 7B, when the recesses 22 formed in the alignment film 20 extend in an arc shape, an ideal inclination angle θ as shown in FIG. 9 is generated. On the other hand, as shown in FIG. 5, when the recesses 22 formed in the alignment film 20 extend in a straight line, the liquid crystal alignment tends to be poor at the boundary between the optical axis pattern regions Pa. Therefore, when the recesses 22 extend in a straight line, it is difficult to produce a clear inclination angle θ as shown in FIG. 9. However, due to the difference between the width W1 of the first pattern region 31a and the width W2 of the second pattern region 31b, a difference in diffraction occurs between the first pattern region 31a and the second pattern region 31b. Therefore, although the effect (amount of color change) is smaller than when the recesses 22 extend in an arc shape, even when the recesses 22 extend in a straight line, the amount of color change can be increased between the first pattern region 31a and the second pattern region 31b. Therefore, visibility differs between the first pattern region 31a and the second pattern region 31b, and the design is maintained.

[0081] Moreover, the width W3 of the third pattern region 31c is smaller than the width W2 of the second pattern region 31b. In this case, the width W3 of the third pattern region 31c may be 80% or less of the width W2 of the second pattern region 31b. This increases the difference between the pitch of the cholesteric liquid crystal compound 35 in the second pattern region 31b and the pitch of the cholesteric liquid crystal compound 35 in the third pattern region 31c in the width direction (X direction) of the second pattern region 31b, etc. This increases the amount of change in color between the second pattern region 31b and the third pattern region 31c. In addition, in this case, for example, the difference between the inclination angle θ of the reflection surface Ref (see FIG. 9) in the second pattern region 31b and the inclination angle θ of the reflection surface Ref in the third pattern region 31c increases. This increases the amount of change in color between the second pattern region 31b and the third pattern region 31c. As a result, the visibility of the second pattern region 31b and the visibility of the third pattern region 31c can be made different, and the design (e.g., designability or authenticity) of the image displayed using the optical film 10 can be improved. In the illustrated example, the width W3 of the third pattern region 31c is larger than the width W1 of the first pattern region 31a. However, this is not limited thereto, and for example, although not illustrated, the width W3 of the third pattern region 31c may be smaller than the width W1 of the first pattern region 31a. Furthermore, although not illustrated, the width W3 of the third pattern region 31c may be larger than the width W2 of the second pattern region 31b.

[0082] The width W1 of the first pattern region 31a, the width W2 of the second pattern region 31b, and the width W3 of the third pattern region 31c may each be 20 μm or less. This makes it easier to recognize the boundary between the first pattern region 31a and the second pattern region 31b, and the boundary between the second pattern region 31b and the third pattern region 31c. This makes it possible to further differentiate the visibility of each pattern region 31, and further improve the design (e.g., designability or authenticity) of an image displayed using the optical film 10.

[0083] The optical film 10 according to the present embodiment may further include other layers such as a functional layer or a pressure-sensitive adhesive layer.

[0084] <Functional layer> The functional layer may have a function as, for example, a hard coat layer, an antiglare layer, an antireflection layer, etc. The functional layer may be formed on, for example, the base layer 11 or the like.

[0085] <Adhesive layer> The adhesive layer may be a layer for bonding each layer of the optical film 10 to each other. The adhesive constituting the adhesive layer may be a general-purpose adhesive such as an acrylic adhesive, a polyester adhesive, a urethane adhesive, or a vinyl adhesive. 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.

[0086] <Specific layer structure of 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 material layer / adhesive layer / retardation layer / adhesive layer / base material layer (8) Base material layer / adhesive layer / retardation layer / adhesive layer / base material layer / functional layer (9) Functional layer / base material layer / adhesive layer / retardation layer / adhesive layer / base material layer (10) Base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer (11) Base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer / functional layer (12) Functional layer / base layer / adhesive layer / retardation layer / alignment film / adhesive layer / base layer (13) Base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer (14) Base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer / functional layer (15) Functional layer / base layer / adhesive layer / alignment film / retardation layer / adhesive layer / base layer

[0087] Next, the polarizing plate 40 and the display device 50 of the image display device 1 will be described.

[0088] [Polarizing plate] The polarizing plate 40 plays a role of exhibiting light absorption performance or 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.

[0089] The polarizer of the polarizing plate 40 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.

[0090] [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.

[0091] <Size, shape, etc.> When manufacturing the display device 50, the optical film 10 and the polarizing plate 40 may be made of a sheet-like material cut to a predetermined size, or a roll-like material obtained by winding a long sheet into a roll. When using a sheet-like material, the size of the optical film 10, etc. is not particularly limited, but the maximum diameter may be about 0.5 inches or more and 500 inches or less. The "maximum diameter" refers to the maximum length when any two points of the optical film 10, etc. are connected. For example, when the optical film 10, etc. is rectangular, the diagonal line of the rectangle is the maximum diameter. When the optical film 10, etc. is circular, the diameter of the circle is the maximum diameter.

[0092] When using a material in a roll form, the width and length of the optical film 10 are not particularly limited, but generally, the width may be about 300 mm or more and 8000 mm or less, and the length may be about 50 m or more and 10000 m or less. The optical film 10 in a roll form can be cut into sheets according to the size of the image display device 1 or the like. When cutting, it is preferable to remove the end of the roll, which has unstable physical properties. When cutting into sheets, the shape of the cut material is not particularly limited, and for example, the shape of the material may be a polygon such as a triangle, a rectangle, or a pentagon, a circle, or a random, indefinite shape.

[0093] Next, a method for producing the optical film 10 according to the present embodiment will be described.

[0094] First, the base layer 11 is prepared.

[0095] 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.

[0096] 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.

[0097] In this manner, the optical film 10 shown in FIG. 4 is obtained.

[0098] As described above, according to the present embodiment, the retardation layer 30 contains a cholesteric liquid crystal compound. The retardation layer 30 has a first pattern region 31a and a second pattern region 31b arranged adjacent to the first pattern region 31a in the first direction X. The first pattern region 31a has a plurality of first optical axis pattern regions Pa1 whose slow axis directions are different from each other, and the plurality of first optical axis pattern regions Pa1 are arranged along the first direction X. The second pattern region 31b has a plurality of second optical axis pattern regions Pa2 whose slow axis directions are different from each other, and the plurality of second optical axis pattern regions Pa2 are arranged along the first direction X. The width W1 of the first pattern region 31a is 80% or less of the width W2 of the second pattern region 31b. As a result, in the width direction (X direction) of the first pattern region 31a, etc., the difference between the pitch of the cholesteric liquid crystal compound 35 in the first pattern region 31a and the pitch of the cholesteric liquid crystal compound 35 in the second pattern region 31b becomes large. Therefore, the amount of change in color can be increased between the first pattern region 31a and the second pattern region 31b. In addition, in this case, for example, the difference between the inclination angle θ of the reflection surface Ref (see FIG. 9) in the first pattern region 31a and the inclination angle θ of the reflection surface Ref in the second pattern region 31b becomes large. Therefore, the visibility of the first pattern region 31a and the visibility of the second pattern region 31b can be made different, and the design of the image displayed using the optical film 10 can be improved. Note that, by making the width W1 of the first pattern region 31a 80% or less of the width W2 of the second pattern region 31b, the design of the image displayed using the optical film 10 can be improved, as will be described in the examples below.

[0099] In the above-mentioned embodiment, an example in which the second optical axis pattern regions Pa2 are arranged along the first direction X has been described, but the present invention is not limited thereto. The second optical axis pattern regions Pa2 may be arranged along a direction different from the first direction X. In this case, for example, as shown in FIG. 12A and FIG. 12B, the second optical axis pattern regions Pa2 may be arranged along the second direction Y. That is, the angle β between the direction in which the second optical axis pattern regions Pa2 are arranged and the first direction X may be 90°. Although not shown, the second optical axis pattern regions Pa2 may be arranged along a direction inclined in both the first direction X and the second direction Y (that is, 0<angle β<90). In the retardation layer 30 shown in FIG. 12A, each pattern region 31 has two optical axis pattern regions Pa. In the retardation layer 30 shown in FIG. 12B, each pattern region 31 has four optical axis pattern regions Pa. Even in these cases, the visibility of the first pattern region 31a and the visibility of the second pattern region 31b can be made different, and the design of the image displayed using the optical film 10 can be improved. The number of optical axis pattern regions Pa in each pattern region 31 may be appropriately changed according to the design displayed by the image display device 1. Also, as shown in Fig. 12C, a plurality of second optical axis pattern regions Pa2 may be arranged along a direction (for example, a second direction Y) different from the first direction X, and the retardation layer 30 may further include a third pattern region 31c.

[0100] In the above-described embodiment, an example in which the retardation layer 30 has a plurality of pattern regions 31 has been described. In this case, for example, as shown in FIG. 13, the retardation layer 30 may have a pattern region 31 in which the cholesteric liquid crystal compound is arranged in a predetermined pattern, and a solid region 32 in which the cholesteric liquid crystal compound is not arranged in a predetermined pattern. As described above, the pattern region 31 may include a plurality of optical axis pattern regions Pa having different slow axis directions. The solid region 32 is a region in which the liquid crystal compound is arranged in a solid pattern. Even in this case, the visibility of the pattern region 31 and the visibility of the solid region 32 can be made different, and the design of the image displayed using the optical film 10 can be improved. In this modified example, the width W4 of the pattern region 31 may be 20 μm or less. This makes it easier to recognize the boundary between the pattern region 31 and the solid region 32. This makes it possible to make the visibility of the pattern region and the solid region 32 even more different, and further improves the design quality (eg, designability or authenticity) of an image displayed using the optical film 10. EXAMPLES

[0101] Next, a specific example of the above embodiment will be described.

[0102] (Example A1) The optical film 10 shown in FIG. 4 was produced. At this time, first, the alignment film 20 shown in FIG. 7 was produced by the imprint method, and then the retardation layer 30 was formed on the alignment film 20. That is, on the alignment film 20 shown in FIG. 7, a retardation layer 30 (angle β=0°) in which a plurality of first optical axis pattern regions Pa1 and a plurality of second optical axis pattern regions Pa2 are arranged along the first direction X was formed. In the retardation layer 30, the width W1 of the first pattern region 31a was set to 1 μm. The width W2 of the second pattern region 31b was set to 2 μm. Furthermore, the number of the first optical axis pattern regions Pa1 and the second optical axis pattern regions Pa2 was set to 8 each.

[0103] When producing the optical film 10, first, a plate for forming the alignment layer 20 was produced. At this time, a master mold having a surface shape designed by simulation was first produced. At this time, a synthetic quartz plate having a size of 6 inches square was used to produce the quartz master mold by an electron beam lithography process using an electron beam drawing device and a dry etching device.

[0104] Next, an ultraviolet-curable resin was poured into the mother mold, and then the ultraviolet-curable resin was irradiated with ultraviolet light to cure the ultraviolet-curable resin. The ultraviolet-curable resin was then peeled off from the mother mold to obtain a resin plate having a shape complementary to the surface shape of the mother mold. Next, a plurality of replica molds of the mother mold, which are molds having a shape complementary to the shape of the resin plate, were produced by electroforming. Next, the plurality of replica molds were wound around a roll to produce a roll-shaped plate.

[0105] Next, a primer layer having the following formulation was applied onto the substrate layer 11 (a cycloolefin polymer having a thickness of 40 μm, Zeon Corporation's trade name "ZEONOR") and dried to form a primer layer having a thickness of 0.5 μm.

[0106] Next, a coating liquid for forming a pattern layer having the following formulation was applied onto the primer layer and dried to form a layer containing an uncured resin.

[0107] Next, the above-mentioned roll-shaped plate was used to form a layer containing uncured resin by the roll-to-roll method, and at the same time, ultraviolet light was irradiated from the side of the base layer 11 to cure the layer containing the formed resin. At this time, the integrated light amount of the ultraviolet light was 500 mJ / cm. 2 Next, the shaped layer was peeled off from the plate to obtain a laminate having the primer layer and the pattern layer (alignment film 20) on the base layer 11.

[0108] Next, the following liquid crystal layer (retardation layer) forming coating solution was applied onto the pattern layer by a continuous roll-to-roll method, dried, and then irradiated with ultraviolet light to form a liquid crystal layer (retardation layer 30). At this time, the integrated light amount of the ultraviolet light was 150 mJ / cm.2 It was decided.

[0109] The liquid crystal layer was made of liquid crystal with an in-plane birefringence (Δn) of 0.15, and the thickness was adjusted so that the in-plane retardation was 275 nm. The in-plane birefringence (Δn) was calculated from the in-plane retardation (Re) and the film thickness d using the above-mentioned formula (1). In Example A1, in which the width W2 of the second pattern region 31b was 2 μm, the liquid crystal layer forming coating liquid was applied four times to obtain the desired film thickness. In Example A4 and the like described later, when the width W1 of the first pattern region 31a or the width W2 of the second pattern region 31b was 15 μm or more and less than 20 μm, the liquid crystal layer forming coating liquid was applied two times to obtain the desired film thickness. In Example A5 and the like described later, when the width W1 or the width W2 was 20 μm or more, the liquid crystal layer forming coating liquid was applied in one time. This is because the liquid crystal orientation differs depending on the size of the width W1 or the width W2.

[0110] By the above steps, an optical film 10 according to Example A1 was produced.

[0111] <Coating solution for forming primer layer> Polyolefin resin: 70 parts by weight (Mitsubishi Chemical Corporation, product name: Surflen P-1000) Silica-based lubricant: 5 parts by weight (Manufactured by CIK Nanotech, product name: SIRMIBK15WT%-E65) Methyl ethyl ketone: 25 parts by weight

[0112] <Coating solution for forming pattern layer> Pentaerythritol triacrylate: 96 parts by weight (Manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) Photopolymerization initiator: 4 parts by weight (IGM, product name: Omnirad184)

[0113] <Liquid crystal layer coating solution> Surfactant: 0.04 parts by weight (BYK-361N (product name), manufactured by BYK-Chemie) ·Rod-shaped liquid crystal molecules: 10 parts by mass (LC242 (product name), manufactured by BASF, in-plane birefringence (Δn)=0.15) Photopolymerization initiator: 0.4 parts by weight (IGM, product name: Omnirad184) Methyl ethyl ketone: 89.6 parts by weight

[0114] Next, the change in color of the optical film 10 was evaluated by evaluating the amount of change in color when viewed from a planar direction and when viewed from an oblique direction.

[0115] The above-mentioned evaluations were performed on areas without defects such as foreign matter, scratches, and wrinkles. The above-mentioned evaluations were performed in an atmosphere with a temperature of 23°C ± 5°C and a relative humidity of 40% to 65%, unless otherwise specified. Furthermore, the measurement sample was exposed to the atmosphere for 30 minutes to 60 minutes before each measurement, unless otherwise specified.

[0116] (Example A2) An optical film 10 was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 2 μm and the width W2 of the second pattern region 31b was 3 μm. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0117] (Example A3) The optical film 10 was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 3 μm, the width W2 of the second pattern region 31b was 7 μm, and the number of the second optical axis pattern regions Pa2 was 30. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0118] (Example A4) The optical film 10 was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 7 μm, the width W2 of the second pattern region 31b was 15 μm, the number of the first optical axis pattern regions Pa1 was 30, and the number of the second optical axis pattern regions Pa2 was 30. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0119] (Example A5) The optical film 10 was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 15 μm, the width W2 of the second pattern region 31b was 20 μm, the number of the first optical axis pattern regions Pa1 was 30, and the number of the second optical axis pattern regions Pa2 was 30. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0120] (Example A6) The optical film 10 was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 25 μm, the width W2 of the second pattern region 31b was 50 μm, the number of the first optical axis pattern regions Pa1 was 30, and the number of the second optical axis pattern regions Pa2 was 30. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0121] (Comparative Example A1) An optical film was produced in the same manner as in Example A1, except that the width W1 of the first pattern region 31a was 15 μm, the width W2 of the second pattern region 31b was 18 μm, the number of the first optical axis pattern regions Pa1 was 30, and the number of the second optical axis pattern regions Pa2 was 30. In addition, the color change of the optical film was evaluated in the same manner as in Example A1.

[0122] (Comparative example A2) An optical film was produced in the same manner as in Example A1, except that an optical film consisting of only a plurality of first pattern regions 31a was produced, the width W1 of the first pattern regions 31a changed continuously from 15 μm to 100 μm, and the number of first optical axis pattern regions Pa1 was 30. In addition, the color change of the optical film was evaluated in the same manner as in Example A1.

[0123] (Reference example) The color change of the optical film was evaluated in the same manner as in Example A1, except that an optical film consisting of only the first pattern region 31a was produced.

[0124] (Example B1) 12A, the retardation layer 30 was formed in which a plurality of second optical axis pattern regions Pa2 were arranged along a direction different from the first direction X, the width W1 of the first pattern region 31a was 15 μm, the width W2 of the second pattern region 31b was 100 μm, the number of first optical axis pattern regions Pa1 was 30, the number of second optical axis pattern regions Pa2 was 30, and the angle β was 90°. The optical film 10 was produced in the same manner as in Example A1, except that. The color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0125] (Example B2) An optical film 10 was produced in the same manner as in Example B1, except that the width W1 of the first pattern region 31a was 100 μm. In addition, a change in color of the optical film 10 was evaluated in the same manner as in Example B1.

[0126] (Example B3) An optical film 10 was produced in the same manner as in Example B1, except that the angle β was 45°. Furthermore, the color change of the optical film 10 was evaluated in the same manner as in Example B1.

[0127] (Example B4) An optical film 10 was produced in the same manner as in Example B1, except that the angle β was 20°. Furthermore, the color change of the optical film 10 was evaluated in the same manner as in Example B1.

[0128] (Example B5) An optical film 10 was produced in the same manner as in Example B1, except that the angle β was 5°. Furthermore, the color change of the optical film 10 was evaluated in the same manner as in Example B1.

[0129] (Example C1) As shown in Fig. 13, the optical film 10 was produced in the same manner as in Example A1, except that a retardation layer 30 having a pattern region 31 and a solid region 32 was formed, the width W4 of the pattern region 31 was 15 µm, and the number of optical axis pattern regions Pa was 30. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example A1.

[0130] (Example C2) An optical film 10 was produced in the same manner as in Example C1, except that the width W4 of the pattern region 31 was 100 μm. In addition, the color change of the optical film 10 was evaluated in the same manner as in Example C1.

[0131] The results are shown in Tables 1 to 3.

[0132] [Table 1]

[0133] [Table 2]

[0134] [Table 3]

[0135] In Tables 1 to 3, "A" in the "Evaluation" column means that the amount of change in color of the optical film 10 between when viewed in a planar view and when viewed at an oblique direction was very large compared to the optical film of the reference example. "B" in the "Evaluation" column means that the amount of change in color of the optical film 10 between when viewed in a planar view and when viewed at an oblique direction was large compared to the optical film of the reference example. "C" in the "Evaluation" column means that there was little difference in color change of the optical film between when viewed in a planar view and when viewed at an oblique direction compared to the optical film of the reference example.

[0136] As a result, as shown in Table 1, the optical films 10 according to Examples A1 to A6, B1 to B5, C1, and C2 were able to increase the amount of change in color of the optical film 10 when viewed in a planar view and when viewed at an oblique direction. In particular, the optical films 10 according to Examples A1 to A4, B1, B3, B4, C1, and C2 were able to increase the amount of change in color of the optical film 10 when viewed in a planar view and when viewed at an oblique direction very much. Therefore, it was found that the optical film 10 according to the present embodiment can improve the design of an image displayed using the optical film 10.

[0137] 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 optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, The retardation layer has a first pattern region and a second pattern region arranged adjacent to the first pattern region in a first direction, The first pattern region has a plurality of first optical axis pattern regions whose slow axis directions are different from each other, The first optical axis pattern regions are arranged along the first direction, The second pattern region has a plurality of second optical axis pattern regions whose slow axis directions are different from each other, The second optical axis pattern regions are arranged along the first direction, An optical film, wherein the width of the first pattern region is 80% or less of the width of the second pattern region.

2. The optical film of claim 1 , wherein the width of the first pattern region and the width of the second pattern region are 20 μm or less.

3. An optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, The retardation layer has a first pattern region and a second pattern region arranged adjacent to the first pattern region in a first direction, The first pattern region has a plurality of first optical axis pattern regions whose slow axis directions are different from each other, The first optical axis pattern regions are arranged along the first direction, The second pattern region has a plurality of second optical axis pattern regions whose slow axis directions are different from each other, The optical film, wherein the second optical axis pattern regions are arranged along a second direction different from the first direction.

4. The optical film of claim 3 , wherein a width of the first pattern region is 80% or less of a width of the second pattern region.

5. The optical film of claim 3 , wherein the width of the first pattern region and the width of the second pattern region are 20 μm or less.

6. An optical film having a retardation layer, The retardation layer contains a cholesteric liquid crystal compound, the retardation layer has a pattern region in which the cholesteric liquid crystal compound is arranged in a predetermined pattern, and a solid region in which the cholesteric liquid crystal compound is not arranged in a predetermined pattern, The optical film, wherein the pattern region includes a plurality of optical axis pattern regions having slow axis directions different from each other.

7. The optical film of claim 6 , wherein the pattern area has a width of 20 μm or less.

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

9. The alignment film includes a UV curable resin, The optical film according to claim 8 , wherein the alignment film has projections and recesses corresponding to the slow axis.

10. The optical film according to any one of claims 1 to 9, and a display device laminated on the optical film.

Images