Transfer film, optical laminate, and virtual image display device

Abstract

To provide a transfer film which allows a less distorted image to be displayed when applied to a virtual image display device, and to provide an optical laminate using the same, and a virtual image display device using the optical laminate.SOLUTION: A transfer film comprises a temporary support body, a photoalignment film in contact with the temporary support body, and a cholesteric liquid crystal layer in contact with the photoalignment film, where the temporary support body is a polyester film and a peeling load between the temporary support body and the photoalignment film is 0.20 N / inch or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transfer film, an optical laminate produced using this transfer film, and a virtual image display device using this optical laminate. [Background technology]

[0002] A virtual reality display device is a display device that allows users to feel as if they are immersed in a virtual world by wearing a dedicated headset on their head and viewing images displayed through a compound lens. Known virtual reality display devices include an image display device and a Fresnel lens, but the distance from the image display device to the Fresnel lens is large, which makes the headset thick and makes it difficult to wear. Therefore, as described in Patent Documents 1 and 2, etc., a composite lens configuration called a pancake lens has been proposed for a virtual reality display device, which has an image display device, a half mirror, a retardation layer, and a reflective polarizer, and which lengthens the optical path and reduces the overall thickness of the headset by causing light rays emitted from the image display device to travel back and forth between the half mirror and the reflective polarizer.

[0003] Known examples of reflective linear polarizers that convert transmitted and reflected light into linearly polarized light include stretched dielectric multilayer films and wire grid polarizers. Also, known examples of reflective circular polarizers that convert transmitted and reflected light into circularly polarized light include cholesteric liquid crystal layers in which a cholesteric liquid crystal phase is fixed.

[0004] FIG. 4 conceptually illustrates an example of a virtual reality display device that uses a cholesteric liquid crystal layer as a reflective circular polarizer. The virtual reality display device 100 shown in FIG. 4 includes, as an example, an image display device and a pancake lens. The image display device includes an image display panel 102, a λ / 4 wave plate 104, a linear polarizer 106, and a λ / 4 wave plate 108 in this order. On the other hand, the pancake lens has, in this order, a half mirror 112, a lens substrate 114, a reflective circular polarizer 116, a retardation layer 118, and a linear polarizer 120. In this pancake lens, the reflective circular polarizer is a reflective circular polarizer that uses a cholesteric liquid crystal layer, and as an example, selectively reflects right-handed circularly polarized light R.

[0005] In the virtual reality display device 100, an image (unpolarized light) emitted by the image display panel 102 passes through a λ / 4 wave plate 104, then passes through a linear polarizer 106 to become linearly polarized light in a predetermined direction, and is then converted into circularly polarized light by a λ / 4 wave plate 108 before being emitted from the image display device. In this example, the image display device emits right-handed circularly polarized light R.

[0006] Half of the right-handed circularly polarized light R emitted from the image display device is transmitted through the half mirror 112, transmitted through the lens substrate 114, and then enters the reflective circular polarizer . As described above, the reflective circular polarizer 116 reflects right-handed circularly polarized light R. Therefore, the right-handed circularly polarized light R is reflected by the reflective circular polarizer 116, passes through the lens substrate 114, and enters the half mirror 112, where half of the light is reflected by the half mirror 112. During this reflection, the right-handed circularly polarized light R is converted into left-handed circularly polarized light L. The left-handed circularly polarized light L reflected by the half mirror 112 passes through the lens substrate 114 and enters the reflective circular polarizer 116 again. The reflective circular polarizer 116 reflects the right-handed circularly polarized light R, so the left-handed circularly polarized light L passes through the reflective circular polarizer 116. The left-handed circularly polarized light L transmitted through the reflective circular polarizer 116 is converted by the retardation layer 118 into linearly polarized light in a direction that passes through the linear polarizer 120, and is transmitted through the linear polarizer 120 and observed by the user E. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2020-519964 [Patent Document 2] U.S. Patent No. 10,394,040 Summary of the Invention [Problem to be solved by the invention]

[0008] As an example, a cholesteric liquid crystal layer is formed by using a resin film such as a polyethylene terephthalate (PET) film as a support, forming an alignment film for aligning a liquid crystal compound on the surface of the support, applying a composition containing the liquid crystal compound to the surface of the alignment film, heating the film to align the liquid crystal compound, and then curing the composition by irradiating it with ultraviolet light or the like. That is, the cholesteric liquid crystal layer is formed as a laminate having a support 124, an alignment film 126, and a cholesteric liquid crystal layer 128, as conceptually shown in the upper part of Fig. 5. In addition, as the alignment film 126, a photo-alignment film that acts as an alignment film when irradiated with light is preferably used.

[0009] A laminate including such a cholesteric liquid crystal layer 128 can be used as a transfer film, taking into consideration the use of roll-to-roll processes that can improve productivity. For example, a laminate as shown in the upper part of Fig. 5 is formed using support 124 as a temporary support. When using it for a pancake lens, as shown in the lower part of Fig. 5, support 124 is peeled off, and the laminate of alignment film 126 and cholesteric liquid crystal layer 128 is used as reflective circular polarizer 116 of the pancake lens.

[0010] However, according to the study by the present inventors, when a virtual image display device is formed using such a transfer film, distortion may occur in the virtual reality image.

[0011] The object of the present invention is to solve the problems of the conventional technology and to provide a transfer film that can realize a virtual image display device that can display images with reduced distortion, an optical laminate produced using this transfer film, and a virtual image display device that uses this optical laminate. [Means for solving the problem]

[0012] The present inventors have conducted extensive research into the above-mentioned problems and have found that the above-mentioned problems can be solved by the following configuration.

[0013] [1] a temporary support; a photo-alignment film disposed in contact with the temporary support; A transfer film comprising: a photo-alignment film; and a cholesteric liquid crystal layer disposed in contact with the photo-alignment film, The temporary support is a polyester film, A transfer film in which the peel load between the temporary support and the photo-alignment film is 0.20 N / inch or less. [2] The transfer film according to [1], wherein the peel load between the temporary support and the photo-alignment film is 0.05 to 0.20 N / inch. [3] The transfer film according to [1] or [2], wherein the photo-alignment film contains a polymer of a compound having a photo-alignment group and a radical polymerizable group. [4] The transfer film according to any one of [1] to [3], wherein the photo-alignment film contains a polymerizable monomer having a difference in ClogP value between the photo-alignment film and the material forming the temporary support of 3.0 or less in absolute value. [5] The transfer film according to any one of [1] to [4], wherein the thickness of the cholesteric liquid crystal layer is 10 μm or more. [6] An optical laminate produced using the transfer film according to any one of [1] to [5]. [7] A virtual image display device comprising the optical laminate according to [6]. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a transfer film that can realize a virtual image display device that can display an image with reduced distortion in a virtual image display device such as a virtual reality display device. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram conceptually illustrating an example of a transfer film of the present invention. [Figure 2] FIG. 1 is a diagram conceptually illustrating an example of a transfer film of the optical laminate of the present invention. [Figure 3] 1 is a diagram conceptually illustrating an example of a virtual image display device of the present invention. [Figure 4] FIG. 1 is a diagram conceptually illustrating an example of a conventional virtual image display device. [Figure 5] FIG. 1 is a diagram conceptually illustrating an example of a conventional transfer film. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to preferred embodiments shown in the accompanying drawings. The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0017] The drawings shown below are conceptual diagrams for explaining the present invention, and therefore the size, thickness, length, shape, and positional relationships of the components, such as spacing between components, do not necessarily correspond to the actual ones. In the present invention, the liquid crystal composition and liquid crystal compound conceptually include those that no longer exhibit liquid crystallinity due to curing or the like. In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, in the present invention, ultraviolet light (ultraviolet light (UV)) refers to light in the wavelength range of 10 to 400 nm among invisible electromagnetic waves.

[0018] FIG. 1 conceptually shows an example of the transfer film of the present invention. The transfer film 10 shown in FIG. 1 includes a temporary support 12 , a photo-alignment film 14 , and a cholesteric liquid crystal layer 16 . 1, the temporary support 12 is peeled off from the transfer film 10 of the present invention, and the laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16 is transferred to another member. For example, the laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16 peeled off from the transfer film 10 is transferred to a member that constitutes a pancake lens of a virtual reality display device, which is an example of a virtual image display device, and forms part of the pancake lens. In the transfer film 10 of the present invention, the temporary support 12 is a polyester film, and the peel load between the temporary support 12 and the photo-alignment film 14 is 0.2 N / inch. The transfer film 10 of the present invention has such a configuration, making it possible to realize a virtual image display device, such as a virtual reality display device, that can display images with reduced distortion. This point will be described in detail later.

[0019] <Temporary support> In the transfer film 10, the temporary support 12 acts as a support for supporting the photo-alignment film 14 and the cholesteric liquid crystal layer 16 until they are peeled off. In the transfer film of the present invention, the temporary support 12 is a polyester film. By using a polyester film as the temporary support 12, the smoothness of the temporary support 12 can be improved, and the penetration of the composition that forms the photo-alignment film 14 described below can be suppressed, making it easier to peel the temporary support 12 and the photo-alignment film 14 from each other.

[0020] There are no limitations on the polyester film used as the temporary support 12, and any known polyester film can be used. Suitable examples include polyester films made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and the like. Among these, PET films are preferably used because they can more suitably obtain the advantages of the polyester films described above. Furthermore, commercially available products such as the Cosmoshine series manufactured by Toyobo Co., Ltd. and the Lumirror series manufactured by Toray Industries, Inc. can also be suitably used as the temporary support 12.

[0021] There is no limitation on the thickness of the temporary support 12. That is, the thickness of the temporary support 12 may be appropriately set to a thickness that can support the photo-alignment film 14 and the cholesteric liquid crystal layer 16 depending on the material forming the temporary support, the size of the transfer film, and the like.

[0022] <Photo-alignment film> In the transfer film 10 of the present invention, a photo-alignment film 14 is provided in contact with a temporary support 12 . The photo-alignment film 14 is intended to align the liquid crystal compound contained in the cholesteric liquid crystal layer 16 that is provided in contact with the photo-alignment film 14, and contains a photo-alignment material that exhibits alignment control power when exposed to polarized or unpolarized light.

[0023] In the transfer film 10 of the present invention, there are no limitations on the photo-alignment film 14, and various photo-alignment films containing known photo-alignment materials can be used. The photo-alignment compound contained in the photo-alignment film 14 is a compound having a photo-alignment group. Here, the term "photo-alignable group" refers to a group having a photo-alignment function that induces rearrangement or an anisotropic chemical reaction when irradiated with anisotropic light (e.g., plane polarized light), and photo-alignable groups that undergo at least one of dimerization and isomerization due to the action of light are preferred because they have excellent alignment uniformity and good thermal and chemical stability. Examples of the photoalignment group include a group having a cinnamoyl structure (skeleton), a group having a coumarin structure (skeleton), a group having a chalcone structure (skeleton), a group having a benzophenone structure (skeleton), and a group having an anthracene structure (skeleton). Among these, a group having a cinnamoyl structure or a group having a coumarin structure is preferred, and a group having a cinnamoyl structure is more preferred.

[0024] The photo-alignment compound may be a low molecular weight compound or a high molecular weight compound, which is a compound having a predetermined repeating unit. Among them, the photoalignment compound is preferably a compound having a repeating unit having a photoalignment group. The photoalignment compound preferably has a repeating unit represented by formula (A).

[0025] [ka]

[0026] In the above formula (A), R 1 represents a hydrogen atom or a substituent, and L 1 represents a divalent linking group, and A represents a photoaligning group represented by formula (a2).

[0027] [ka]

[0028] In the above formula (a2), * represents L 1 represents the bonding position with R 3 ~R 7 each independently represents a hydrogen atom or a substituent, and two adjacent groups may be bonded to form a ring.

[0029] R 1 The substituent represented by one embodiment of the formula (1) is preferably a halogen atom, a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, a linear halogenated alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a cyano group, or an amino group.

[0030] L 1 The divalent linking group represented by the formula (I) is preferably a divalent linking group formed by combining at least two or more groups selected from the group consisting of a linear, branched, or cyclic alkylene group having 1 to 18 carbon atoms which may have a substituent, an arylene group having 6 to 12 carbon atoms which may have a substituent, an ether group (-O-), a carbonyl group (-C(=O)-), and an imino group (-NH-) which may have a substituent.

[0031] R 3 ~R7 The substituents represented by one embodiment of the formula (1) are each preferably independently a halogen atom, a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, a linear halogenated alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a cyano group, or an amino group.

[0032] The content of the repeating unit having a photoalignable group in the photoalignment compound is not particularly limited, and is preferably 0.5 to 25 mass %, more preferably 1 to 20 mass %, based on the total repeating units in the photoalignment compound.

[0033] The photoalignment compound may further have a polymerizable group, such as a radically polymerizable group (e.g., a (meth)acryloyl group) or a cationic polymerizable group. The photo-alignment compound is preferably a compound having a repeating unit having a polymerizable group, i.e., the photo-alignment compound is preferably a compound having a repeating unit having a photo-alignment group and a repeating unit having a polymerizable group. The photoalignment compound preferably has a repeating unit represented by formula (B).

[0034] [ka]

[0035] In the above formula (B), R 2 represents a hydrogen atom or a substituent, and L 2 represents a divalent linking group, and B represents a polymerizable group. R 2 Examples of the substituents represented by one embodiment of the formula (A) include R 1 Examples of the substituent include those described as examples of the substituents shown in one embodiment of the above. In addition, L 2 The divalent linking group represented by is L in the above formula (A). 1 Examples of the divalent linking group include those described above for the divalent linking group represented by the formula: Examples of the polymerizable group represented by B include the groups exemplified above.

[0036] The content of repeating units having a polymerizable group in the photoalignment compound is not particularly limited, and is preferably 75 to 99.5 mass %, more preferably 80 to 99 mass %, based on the total repeating units in the photoalignment compound.

[0037] In the transfer film 10 of the present invention, the photo-alignment film 14 may contain a polymerizable monomer unevenly distributed in the temporary support material. The polymerizable monomer unevenly distributed in the temporary support material is a monomer that has a similar affinity to the material forming the temporary support 12. Specifically, the polymerizable monomer unevenly distributed in the temporary support material is a polymerizable monomer whose calculated solubility parameter (ClogP value) is close to that of the material forming the temporary support 12 and whose molecular weight is not too large. As described above, in the present invention, the material forming the temporary support 12 is polyester. The photo-alignment film 14 contains such a polymerizable monomer unevenly distributed in the temporary support material, which can suppress a reaction between the temporary support 12 and the photo-alignment film 14 caused by ultraviolet irradiation or the like when forming the cholesteric liquid crystal layer 16 described below. As a result, the photo-alignment film 14 contains the polymerizable monomer unevenly distributed in the temporary support material, which can reduce the peel load between the temporary support 12 and the photo-alignment film 14.

[0038] The polymerizable monomer unevenly distributed in the temporary support material is preferably a monomer whose absolute value of the difference in ClogP value from the material forming the temporary support 12 is 3.0 or less, more preferably 2.0 or less, and even more preferably 1.0 or less. There is no particular lower limit for the absolute value of the difference in ClogP value, but it is often 0 or more. ClogP is the value obtained by calculating the common logarithm logP of the partition coefficient P between 1-octanol and water. Although known methods and software can be used to calculate ClogP, unless otherwise specified, the present invention uses the ClogP program incorporated into Cambridge Soft's ChemBioDraw Ultra 12.0. The unevenly distributed polymerizable monomer for the temporary support material preferably has a molecular weight of 200 to 800, more preferably 200 to 600, and even more preferably 200 to 400.

[0039] For example, when the material forming the temporary support 12 is PET, the following compounds 1 to 4 are preferably exemplified as the polymerizable monomer unevenly distributed in the temporary support material, that is, the polymerizable monomer unevenly distributed in PET.

[0040] compound 1 [ka] compound 2 [ka] compound 3 [ka] compound 4 [ka]

[0041] The ClogP values ​​and molecular weights of compounds 1 to 4 are shown in the table below. The ClogP value of PET is 2.6.

[0042] [Table 1]

[0043] In the transfer film 10 of the present invention, the photo-alignment film 14 functions as a light interference layer between the cholesteric liquid crystal layer 16 and an adjacent layer (film) depending on the material (refractive index) and film thickness. The photo-alignment film 14 acts as a light interference layer, thereby making it possible to suppress unnecessary reflection of light at the interface between the cholesteric liquid crystal layer 16 and the layer adjacent thereto via the photo-alignment film 14 . For example, as conceptually shown in Figures 3 and 4, the transfer film 10 of the present invention is used as the optical laminate of the present invention in a pancake lens of a virtual reality display device 40 described below. In this case, a laminate of a photo-alignment film 14 and a cholesteric liquid crystal layer 16 made of the transfer film 10 of the present invention is, for example, attached to a lens substrate 34 with an adhesive, with the photo-alignment film 14 side facing the lens substrate 34. In this case, the photo-alignment film 14 functions as a light interference layer, thereby preventing unnecessary light reflection at the interface between the cholesteric liquid crystal layer 16 and the adhesive layer (adhesive). This makes it possible to suppress the occurrence of so-called ghosts (leakage light) in the virtual reality display device 40, in which an extra image is observed by the user due to unnecessary reflection of light at the interface between the cholesteric liquid crystal layer 16 and the adhesive layer.

[0044] In the transfer film 10 of the present invention, there is no limitation on the thickness of the photo-alignment film 14, and the thickness can be appropriately set so that the photo-alignment film 14 can function sufficiently as an alignment film for the cholesteric liquid crystal layer, depending on the material for forming the photo-alignment film 14 and the material for forming the cholesteric liquid crystal layer, etc. In order for the optical alignment film 14 to function as an optical interference layer, it is preferable that the thickness of the optical alignment film 14 be at least a fraction of the wavelength of the corresponding light, i.e., the light selectively reflected by the cholesteric liquid crystal layer.

[0045] The thickness of the photo-alignment film 14 is preferably 50 nm or more. By making the thickness of the photo-alignment film 14 50 nm or more, the photo-alignment film 14 can be easily made to function as a light interference layer, and good coating suitability can be obtained, which is preferable. The thickness of the photo-alignment film 14 is more preferably 100 nm or more, and further preferably 200 nm or more. The thickness of the photo-alignment film 14 is preferably 10 μm or less. By setting the thickness of the photo-alignment film 14 to 10 μm or less, good coating suitability can be obtained, and adhesion to the lens substrate can be improved, which is preferable. The thickness of the photo-alignment film 14 is more preferably 5 μm or less, and even more preferably 3 μm or less.

[0046] There is no limitation on the method for forming the photo-alignment film 14, and various known methods depending on the material for forming the photo-alignment film 14 can be used. One example is a method in which a composition containing a photo-alignment material is prepared, coated on a temporary support, the coating is dried, for example by heating, and then the dried coating is irradiated with polarized or unpolarized light to form a photo-alignment film 14. The light to be irradiated may be ultraviolet light, visible light, or infrared light, and light of a wavelength appropriate for the photo-alignment material may be appropriately selected. When irradiating polarized light, a light source that emits polarized light may be used, or a non-polarized light source may be polarized using a wire grid polarizer or the like.

[0047] <Cholesteric liquid crystal layer> In the transfer film 10 of the present invention, a cholesteric liquid crystal layer 16 is provided in contact with the photo-alignment film 14 . The cholesteric liquid crystal layer 16 is a layer formed by fixing a cholesteric liquid crystal phase, and has a helical structure in which the liquid crystal compounds are spirally wound and stacked in the thickness direction. One helical pitch (helical pitch P) is a configuration in which the liquid crystal compounds are spirally wound and stacked, and the helically wound liquid crystal compounds 30 are stacked at multiple pitches. As is well known, a cholesteric liquid crystal layer selectively reflects light in a specific wavelength range depending on the length of the helical pitch P. Also, a cholesteric liquid crystal layer reflects either right-handed or left-handed circularly polarized light and transmits the other depending on the rotation direction of the liquid crystal compound in the helical structure. Therefore, the cholesteric liquid crystal layer 16 acts as a reflective circular polarizer that selectively reflects either right-handed or left-handed circularly polarized light and transmits the other in a specific wavelength range.

[0048] In the transfer film 10 of the present invention, the cholesteric liquid crystal layer 16 can be any of various known cholesteric liquid crystal layers. An example is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, as described in JP-A-2020-060627.

[0049] The cholesteric liquid crystal layer 16 may include a cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound and a cholesteric liquid crystal layer containing a discotic liquid crystal compound. With this configuration, the cholesteric liquid crystal phase containing the rod-shaped liquid crystal compound has a positive Rth, while the cholesteric liquid crystal phase containing the discotic liquid crystal compound has a negative Rth, so that the Rths cancel each other out, and when used in, for example, a virtual image display device, image quality degradation caused by incident light from an oblique direction can be suppressed.

[0050] The cholesteric liquid crystal layer 16 may also have a plurality of cholesteric liquid crystal layers that selectively reflect light in different wavelength ranges. For example, the cholesteric liquid crystal layer 16 may have a cholesteric liquid crystal layer that selectively reflects blue light, a cholesteric liquid crystal layer that selectively reflects green light, and a cholesteric liquid crystal layer that selectively reflects red light. With such a configuration, the transfer film 10 of the present invention can accommodate light in various wavelength ranges, and when used in a virtual image display device, for example, it can display a full-color image consisting of blue, green, and red images. Furthermore, the cholesteric liquid crystal layer 16 may have a pitch gradient structure in which the helical pitch of the cholesteric liquid crystal phase changes continuously in the thickness direction.

[0051] There is no limitation on the thickness of the cholesteric liquid crystal layer 16, and it may be set appropriately depending on the desired properties of the cholesteric liquid crystal layer 16. Here, the thickness of the cholesteric liquid crystal layer 16 is preferably 10 μm or more, which is preferable in that a wide band of light in the visible range can be reflected by making the thickness of the cholesteric liquid crystal layer 16 10 μm or more. The thickness of the cholesteric liquid crystal layer 16 is more preferably 15 μm or more, and even more preferably 20 μm or more. The thickness of the cholesteric liquid crystal layer 16 is preferably 50 μm or less, taking into consideration the thickness of the transfer film 10 after the temporary support 12 is peeled off. When the cholesteric liquid crystal layer 16 has a plurality of cholesteric liquid crystal layers, the thickness of the cholesteric liquid crystal layer 16 is the total thickness of all the cholesteric liquid crystal layers.

[0052] The cholesteric liquid crystal layer 16 may be formed by a known method. As an example, a composition prepared by dissolving a liquid crystal compound, a chiral agent, a polymerization initiator, and optionally a surfactant, etc. in a solvent is applied to the photo-alignment film 14, the liquid crystal compound in the coating is aligned by heating or the like, and the composition is dried to obtain a coating, and ultraviolet light is irradiated onto this coating to harden the liquid crystal composition, thereby forming the liquid crystal layer.

[0053] The transfer film 10 of the present invention comprises a temporary support 12 which is a polyester film as described above, a photo-alignment film 14 in contact with the temporary support 12, and a cholesteric liquid crystal layer 16 in contact with the photo-alignment film 14, and the peel load between the temporary support 12 and the photo-alignment film 14 is 0.20 N / inch or less. The transfer film 10 of the present invention has such a configuration, making it possible to realize a virtual image display device such as a virtual reality display device that can display an image with reduced distortion.

[0054] As described above, when a laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16 is used in an optical element, the photo-alignment film 14 may function as a light interference layer. Also, when a laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16 is used in an optical element, the photo-alignment film may function as a refractive index gradient layer. Furthermore, in the laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16, the photo-alignment film 14 may function as a protective layer for the cholesteric liquid crystal layer 16. That is, in the laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16, the photo-alignment film 14 may be used as a functional layer that exhibits various functions. Therefore, for example, as described above, in a pancake lens used in a virtual reality display device, the support may be peeled off from a laminate having a support, a photo-alignment film, and a cholesteric liquid crystal layer, and the laminate of the photo-alignment film and the cholesteric liquid crystal layer may be used in the pancake lens as a reflective circular polarizer.

[0055] However, in a virtual reality display device that uses a pancake lens including a laminate of a photo-alignment film and a cholesteric liquid crystal layer from which the support has been peeled off, distortion may occur in the image (virtual reality image). The present inventors have conducted extensive research into the cause of this problem. As a result, they have discovered that the image distortion is caused by the inclusion of a layer (film) with an uneven surface within the pancake lens. Furthermore, they have discovered that the surface of the photo-alignment film is rough, and this roughness is the cause of the image distortion. In addition, the inventors discovered that when the support is peeled off from a laminate of the support, the photo-alignment film, and the cholesteric liquid crystal layer, the surface of the photo-alignment film becomes rough, and that the stronger the force required to peel the support and the photo-alignment film, the greater the roughness of the surface of the photo-alignment film.

[0056] The transfer film 10 of the present invention was made based on this finding, and comprises a polyester temporary support 12, a photo-alignment film 14 in contact with the temporary support 12, and a cholesteric liquid crystal layer 16 in contact with the photo-alignment film 14. The transfer film is designed to peel off the temporary support 12, and the peel load between the temporary support 12 and the photo-alignment film 14 is set to 0.20 N / inch or less. The transfer film 10 of the present invention has such a configuration, and therefore, when the temporary support 12 and the photo-alignment film 14 are peeled off by a conventional method, the surface of the photo-alignment film 14 can be prevented from becoming rough. As a result, when a laminate of the photo-alignment film 14 and the cholesteric liquid crystal layer 16 from which the temporary support 12 has been peeled off is used as a reflective circular polarizer in a pancake lens of a virtual reality display device, for example, it becomes possible to realize a virtual reality display device in which distortion of the image (virtual image) is suppressed.

[0057] In the transfer film 10 of the present invention, if the peel load between the temporary support 12 and the photo-alignment film 14 exceeds 0.20 N / inch, the surface of the photo-alignment film 14 will become rough when the temporary support 12 and the photo-alignment film 14 are peeled off, and image distortion cannot be sufficiently suppressed, for example, in a virtual image display device such as a virtual reality display device. The peel load between the temporary support 12 and the photo-alignment film 14 is preferably 0.15 N / inch or less, and more preferably 0.10 N / inch or less.

[0058] In the transfer film 10 of the present invention, there is no lower limit to the peel load between the temporary support 12 and the photo-alignment film 14 . However, if the peel load between the temporary support 12 and the photo-alignment film 14 is too small, the temporary support 12 may unintentionally peel off from the photo-alignment film 14, for example, during transport in a roll-to-roll process or when handling the transfer film 10. Considering this point, the peel load between the temporary support 12 and the photo-alignment film 14 is preferably 0.03 N / inch or more, more preferably 0.04 N / inch or more, and even more preferably 0.05 N / inch or more.

[0059] In the present invention, the peel load may be measured using a load measuring device (force gauge) or the like in accordance with the 180° peel test of JIS Z 0237:2022. The peel load is measured twice and the average value is used.

[0060] There are no limitations on the method for controlling the peel load between the temporary support 12 and the photo-alignment film 14 to 0.20 N / inch or less, and various methods can be used depending on the materials used to form the temporary support 12 (polyester film) and the photo-alignment film 14.

[0061] As described above, when forming the cholesteric liquid crystal layer 16, ultraviolet light may be irradiated to polymerize the liquid crystal compound and harden the cholesteric liquid crystal layer 16. According to the studies of the present inventors, during this ultraviolet light irradiation, the temporary support 12, which is a polyester film, absorbs the short-wavelength ultraviolet light contained in the ultraviolet light to generate radicals, which react with photopolymerizable groups in the photo-alignment film 14, increasing the peel load. Taking this into consideration, one example of a method for controlling the peel load between the temporary support 12 and the photo-alignment film 14 to 0.20 N / inch or less is to eliminate short-wavelength ultraviolet light of 320 nm or less from the ultraviolet light used to harden the cholesteric liquid crystal layer 16. Specifically, one example is a method in which the cholesteric liquid crystal layer 16 is irradiated with ultraviolet light for curing through a filter (band pass filter, high pass filter, long pass filter) having a transmission band exceeding 340 nm. Another example of the method is to use an LED having a central wavelength of more than 340 nm as a light source to irradiate the cholesteric liquid crystal layer 16 with ultraviolet light for curing. Specifically, an example of the method is to use an LED having a central wavelength of 365 nm as a light source to irradiate the cholesteric liquid crystal layer 16 with ultraviolet light for curing.

[0062] As a method for controlling the peel load between the temporary support 12 and the photo-alignment film 14 to 0.20 N / inch or less, a method of using a thermosetting photo-alignment film as the photo-alignment film 14 can also be used. By using a thermosetting photo-alignment film 14, it is possible to suppress the reaction between the radicals generated in the temporary support 12 during irradiation with ultraviolet light to cure the cholesteric liquid crystal layer 16 and the photopolymerizable groups of the photo-alignment film 14, which is a factor that increases the peel load. As a result, it is possible to control the peel load between the temporary support 12 and the photo-alignment film 14 to 0.20 N / inch or less.

[0063] The optical laminate of the present invention is an optical laminate formed using such a transfer film 10 of the present invention. FIG. 2 conceptually shows an example of the optical laminate of the present invention. 2 includes a linear polarizer 24, a retardation layer 26, and a reflective circular polarizer 28. The reflective circular polarizer 28 is obtained by peeling off the temporary support 12 from the transfer film 10 of the present invention described above, and is a laminate of a cholesteric liquid crystal layer 16 and a photo-alignment film 14.

[0064] As will be described later, such an optical laminate 20 constitutes, as an example, a pancake lens used in a virtual reality display device, which is a virtual image display device. In the optical stack 20, the reflective circular polarizer 28, the photo-alignment film 14 and the cholesteric liquid crystal layer 16 are as described above.

[0065] <Retardation layer> In the optical laminate 20 of the present invention, various known retardation layers can be used as the retardation layer 26 . In the optical laminate 20, the retardation layer 26 has a function of converting incident circularly polarized light into linearly polarized light. For example, the retardation layer 26 can be a retardation layer (λ / 4 wave plate) whose Re is approximately ¼ wavelength at any wavelength in the visible range. In this case, the in-plane retardation Re(550) at a wavelength of 550 nm is preferably 120 to 150 nm, more preferably 125 to 145 nm, and even more preferably 135 to 140 nm. Furthermore, the retardation layer 26 in which Re is approximately 3 / 4 wavelength and Re is approximately 5 / 4 wavelength are also preferable because they can convert linearly polarized light into circularly polarized light. Furthermore, the retardation layer 26 preferably has reverse dispersion with respect to wavelength. This is because reverse dispersion makes it possible to convert circularly polarized light into linearly polarized light over a wide wavelength range in the visible region. Here, having reverse dispersion with respect to wavelength means that the value of retardation at a wavelength increases as the wavelength increases. A retardation layer having reverse dispersion properties can be produced by uniaxially stretching a polymer film such as a modified polycarbonate resin film having reverse dispersion properties, for example, with reference to JP-A-2017-049574.

[0066] <Linear polarizer> In the optical laminate 20 of the present invention, various known linear polarizers can be used as the linear polarizer 24 . Among these, an absorptive linear polarizer is preferable as the linear polarizer 24. An absorptive linear polarizer absorbs incident light linearly polarized in the absorption axis direction and transmits light linearly polarized in the transmission axis direction. A general polarizer can be used as the linear polarizer 24. Examples include a polarizer in which a dichroic material is dyed onto polyvinyl alcohol or other polymer resin and then oriented by stretching, and a polarizer in which a dichroic material is oriented by utilizing the orientation of a liquid crystal compound. In the optical laminate 20, the direction of the transmission axis of the linear polarizer 24 preferably coincides with the direction of the polarization axis of the light converted into linearly polarized light by the retardation layer 26. For example, when the retardation layer 26 is a layer having a phase difference of ¼ wavelength, the angle between the transmission axis of the linear polarizer and the slow axis of the retardation layer is preferably approximately 45°.

[0067] The optical laminate 20 of the present invention may have a positive C plate between the reflective circular polarizer 28 (cholesteric liquid crystal layer 16) and the retardation layer 26. The positive C plate is a retardation layer in which Re is substantially zero and Rth has a negative value. A positive C plate can be obtained, for example, by vertically aligning a rod-shaped liquid crystal compound. For details of a method for producing a positive C plate, see, for example, JP 2017-187732 A, JP 2016-053709 A, and JP 2015-200861 A. The positive C plate functions as an optical compensation layer for increasing the degree of polarization of transmitted light with respect to obliquely incident light.

[0068] As described above, the reflective circular polarizer 28 has a cholesteric liquid crystal layer 16. When the cholesteric liquid crystal layer 16 is a layer formed by fixing a cholesteric liquid crystal phase containing, for example, a rod-shaped liquid crystal compound, the cholesteric liquid crystal layer 16 has a positive Rth. In this case, if light is incident on the reflective circular polarizer 28 from an oblique direction, the polarization states of the reflected light and transmitted light may change due to the action of Rth, and the degree of polarization of the transmitted light may decrease. If a positive C plate is provided near the reflective circular polarizer 28, the change in the polarization state of obliquely incident light can be further suppressed, and the decrease in the degree of polarization of the transmitted light can be further suppressed, thereby making it possible to further suppress so-called ghosts (leakage light) in virtual image display devices such as virtual reality display devices.

[0069] In addition to these layers, the optical layered body of the present invention may have various other layers, such as a hard coat layer, an anti-reflection layer, and an ultraviolet absorbing layer, as necessary.

[0070] In the optical laminate 20 of the present invention, each layer is adhered with an adhesive (adhesive layer) as needed. There are no limitations on the adhesive, and various known adhesives and pressure-sensitive adhesives can be used depending on the optical properties required for the optical laminate 20. In addition, various commercially available adhesives such as commercially available OCA (Optical Clear Adhesive) can also be suitably used.

[0071] The virtual image display device of the present invention is a virtual image display device that includes the optical laminate of the present invention. FIG. 3 conceptually shows an example of a virtual reality display device as a virtual image display device of the present invention, which uses the optical laminate 20 shown in FIG.

[0072] The virtual reality display device 40 shown in FIG. 3 includes an image display device and a pancake lens. The image display device includes an image display panel 42, a λ / 4 wave plate 46, a linear polarizer 48, and a λ / 4 wave plate 50 in this order.

[0073] The pancake lens has, in this order, a half mirror 32, a lens substrate (lens) 34, a reflective circular polarizer 28, a retardation layer 26, and a linear polarizer 24. The reflective circular polarizer 28, the retardation layer 26, and the linear polarizer 24 are the optical laminate 20 of the present invention described above, and therefore the reflective circular polarizer 28 has a cholesteric liquid crystal layer 16 and a photo-alignment film 14. 3, the reflective circular polarizer 28 is provided with the photo-alignment film 14 facing the lens substrate 34. As an example, the pancake lens is formed by adhering the photo-alignment film 14 of the reflective circular polarizer 28 and the lens substrate 34 with an adhesive. As described above, the optical laminate 20 constituting the pancake lens may have a positive C plate between the reflective circular polarizer 28 and the retardation layer 26, if necessary.

[0074] In the virtual reality display device 40, the image display panel 42 is a known image display panel such as a liquid crystal display panel, an organic EL display panel, or a micro LED display panel. The λ / 4 wave plates 46 and 50 are similar to the retardation layers described above. The linear polarizer 48 is also similar to the linear polarizer described above.

[0075] In the virtual reality display device 40 shown in Figure 3, the image (virtual reality image (unpolarized)) emitted by the image display panel 42 passes through the λ / 4 wave plate 46, then passes through the linear polarizer 48 to become linearly polarized light in a predetermined direction, and is converted into circularly polarized light by the λ / 4 wave plate 50 and emitted from the image display device. In this example, as an example, the image display device emits right-handed circularly polarized light R. The λ / 4 wave plate 46 and the linear polarizer 48 constitute an anti-reflection film of the image display panel 42 .

[0076] Half of the right-handed circularly polarized light R emitted from the image display device is transmitted through the half mirror 32, transmitted through the lens substrate , and then enters the reflective circular polarizer . In this example, the reflective circular polarizer 28 (cholesteric liquid crystal layer 16) selectively reflects right-handed circularly polarized light R. Therefore, the right-handed circularly polarized light R is reflected by the reflective circular polarizer 28, passes through the lens substrate 34, and enters the half mirror 32, where half of the light is reflected. During this reflection, the right-handed circularly polarized light R is converted into left-handed circularly polarized light L. The left-handed circularly polarized light L reflected by the half mirror 32 passes through the lens substrate 34 and enters the reflective circular polarizer 28 again. As described above, the reflective circular polarizer 28 reflects the right-handed circularly polarized light R, and therefore the left-handed circularly polarized light L passes through the reflective circular polarizer 28. The left-handed circularly polarized light transmitted through the reflective circular polarizer 28 is converted by the retardation layer 26 into linearly polarized light in a direction that passes through the linear polarizer 24, and is transmitted through the linear polarizer 24 and observed by the user E.

[0077] Here, in the virtual reality display device 40, the optical laminate 20 constituting the pancake lens is the optical laminate of the present invention, i.e., the reflective circular polarizer 28 is a laminate of a photo-alignment film 14 and a cholesteric liquid crystal layer 16 produced using the transfer film of the present invention. Therefore, the optical alignment film 14 of the reflective circular polarizer 28 has a high surface smoothness, and as a result, the virtual reality display device 40 is able to display images with reduced distortion.

[0078] As described above, the photo-alignment film 14 can also function as a light interference layer depending on the refractive index and film thickness. As described above, the pancake lens is formed by adhering the optical alignment film 14 of the reflective circular polarizer 28 to the lens substrate 34 with an adhesive. In this case, the optical alignment film 14 acts as an optical interference layer between the adhesive and the cholesteric liquid crystal layer 16. This prevents the right-handed circularly polarized light R reflected by the cholesteric liquid crystal layer 16 from being unnecessarily reflected at the interface between the cholesteric liquid crystal layer 16 and the adhesive layer, thereby preventing the generation of ghosts (leakage light) caused by this reflected light.

[0079] The above describes the transfer film, optical laminate, and virtual image display device of the present invention, but the present invention is not limited to this, and various improvements and modifications may be made within the scope that does not deviate from the gist of the present invention. [Example]

[0080] The features of the present invention will be explained in more detail below with reference to examples. Note that the materials, amounts used, ratios, processing details, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Furthermore, configurations other than those shown below can also be used without departing from the spirit of the present invention.

[0081] [Preparation of coating solution for reflective layer]

[0082] <Reflective layer coating liquid R-1> The composition shown below was stirred and dissolved in a container kept at 70° C. to prepare a coating solution R-1 for a reflective layer, where R represents a coating solution using a rod-like liquid crystal compound.

[0083] ---------------------------------------------------------------------------------- Reflective layer coating liquid R-1 ---------------------------------------------------------------------------------- Methyl ethyl ketone 120.9 parts by mass Cyclohexanone 21.3 parts by mass 100.0 parts by mass of the following mixture of rod-shaped liquid crystal compounds: 3.00 parts by mass of the following photopolymerization initiator B 3.87 parts by mass of the following chiral agent A 0.1 parts by mass of the following surfactant S1 ----------------------------------------------------------------------------------

[0084] Mixture of rod-shaped liquid crystal compounds X [ka]

[0085] In the above mixture X, the numerical values ​​are in mass %. R is a group bonded via an oxygen atom. Furthermore, the average molar absorption coefficient of the above rod-shaped liquid crystal compound in the wavelength range of 300 to 400 nm was 140 / mol cm.

[0086] Chiral agent A [ka]

[0087] Surfactant S1 [ka]

[0088] Photopolymerization initiator B [ka]

[0089] Chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.

[0090] <Reflective layer coating liquid R-2> The coating solution was prepared in the same manner as for the reflective layer coating solution R-1, except that the amount of chiral agent A added was changed as shown in Table 2 below.

[0091] Table 2. Amount of chiral agent in coating solution containing rod-shaped liquid crystal compound [Table 2]

[0092] <Reflective layer coating solution D-1> The composition shown below was stirred and dissolved in a container kept at 50° C. to prepare a coating solution D-1 for a reflective layer, where D represents a coating solution using a discotic liquid crystal compound.

[0093] ---------------------------------------------------------------------------------- Reflective layer coating solution D-1 ---------------------------------------------------------------------------------- 80 parts by mass of the following discotic liquid crystal compound (A): 20 parts by mass of the following discotic liquid crystal compound (B): 10 parts by mass of the following polymerizable monomer E1 0.3 parts by mass of the following surfactant S2 Photopolymerization initiator (BASF, Irgacure 907) 3 parts by weight 5.19 parts by mass of the above chiral agent A Methyl ethyl ketone 290 parts by mass Cyclohexanone 50 parts by mass ----------------------------------------------------------------------------------

[0094] Discotic Liquid Crystal Compound (A) [ka] Discotic Liquid Crystal Compound (B) [ka]

[0095] Polymerizable Monomer E1 [ka]

[0096] Surfactant S2 [ka]

[0097] <Reflective layer coating liquid D-2, 3> The coating solution was prepared in the same manner as in the coating solution D-1 for reflective layer, except that the amount of chiral agent A added was changed as shown in Table 3 below.

[0098] Table 3. Amount of chiral agent in coating solution containing discotic liquid crystal compound [Table 3]

[0099] <Alignment layer forming coating solution PA-1> The composition shown below was stirred and dissolved in a container at room temperature to prepare a coating liquid for forming an alignment film PA-1.

[0100] ---------------------------------------------------------------------------------- (Alignment film forming coating solution PA-1) ---------------------------------------------------------------------------------- 100.00 parts by mass of the following polymer M-PA-1 5.00 parts by weight of the acid generator PAG-1 (listed below) 0.005 parts by weight of the following acid generator CPI-110TF Xylene 3660.00 parts by mass Methyl isobutyl ketone 366.00 parts by mass ----------------------------------------------------------------------------------

[0101] Polymer M-PA-1 [ka]

[0102] Acid generator PAG-1 [ka]

[0103] Acid generator CPI-110TF [ka]

[0104] [Preparation of reflective circular polarizer 1] As a temporary support, a PET film (Cosmoshine A4265, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm was prepared.

[0105] The alignment film-forming coating liquid PA-1 was applied to this temporary support with a wire bar, and then thermally cured by drying for 120 seconds with hot air at 140° C. The thickness of the coating film after drying was 80 nm.

[0106] Next, the dried coating was exposed to an illuminance of 7mW / cm 2 , irradiation dose 7.9mJ / cm 2 A photo-alignment film was formed by irradiating the alignment film side with linearly polarized ultraviolet light (wavelength 313 nm). Linearly polarized ultraviolet light with a wavelength of 313 nm was obtained by passing ultraviolet light emitted from a mercury lamp through a bandpass filter with a transmission band at 313 nm and a wire grid polarizer.

[0107] The surface of the formed photo-alignment film was coated with the reflective layer coating liquid R-1 using a wire bar coater, and dried at 100° C. for 72 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm 2 , irradiation amount 100mJ / cm 2 The coating was cured by irradiating it with light from a high-pressure mercury lamp, thereby forming a first blue light reflective layer (first layer) made of a cholesteric liquid crystal layer. In all cases, light was irradiated from the cholesteric liquid crystal layer side. The coating thickness of the coating solution was adjusted so that the film thickness of the first blue light reflective layer after curing would be 2.0 μm.

[0108] Next, a discharge rate of 150 W·min / m was applied to the surface of the first blue light reflective layer. 2 Thereafter, the reflective layer coating solution D-1 was applied onto the corona-treated surface using a wire bar coater, and dried at 115° C. for 150 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 60°C, with an illuminance of 50 mW / cm 2 , irradiation amount 50mJ / cm 2 The coating was cured by irradiating it with light from a high-pressure mercury lamp through a long-pass filter with a transmission band of wavelengths above 340 nm, thereby forming a second blue-light reflective layer (second layer) made of a cholesteric liquid crystal layer. In all cases, light was irradiated from the cholesteric liquid crystal layer side. The coating thickness of the coating solution was adjusted so that the film thickness of the second blue light reflective layer after curing would be 2.5 μm.

[0109] Next, a discharge rate of 150 W·min / m was applied to the surface of the second blue light reflective layer. 2 Thereafter, the reflective layer coating solution D-2 was applied onto the corona-treated surface using a wire bar coater, and dried at 120°C for 150 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 60°C, with an illuminance of 100 mW / cm 2 , irradiation amount 450mJ / cm 2 The coating was cured by irradiating it with light from a high-pressure mercury lamp through a long-pass filter with a transmission band of wavelengths above 340 nm, thereby forming a green light-reflecting layer (third layer) made of a cholesteric liquid crystal layer. In all cases, light was irradiated from the cholesteric liquid crystal layer side. The coating thickness of the coating solution was adjusted so that the film thickness of the green light reflective layer after curing would be 3.5 μm.

[0110] Next, the reflective layer coating solution R-2 was applied to the surface of the green light reflective layer using a wire bar coater, and dried at 100° C. for 72 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm 2 , irradiation amount 100mJ / cm 2 The coating film was cured by irradiating it with light from a metal halide lamp, thereby forming a yellow light reflective layer (fourth layer) made of a cholesteric liquid crystal layer. In all cases, light was irradiated from the cholesteric liquid crystal layer side. The coating thickness of the coating solution was adjusted so that the film thickness of the yellow light reflective layer after curing would be 4.2 μm.

[0111] Next, a discharge rate of 150 W·min / m was applied to the surface of the yellow light reflective layer. 2 Thereafter, the reflective layer coating solution D-3 was applied onto the corona-treated surface using a wire bar coater, and dried at 120°C for 150 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 60°C, with an illuminance of 100 mW / cm 2 , irradiation amount 100mJ / cm 2The coating was cured by irradiating it with light from a high-pressure mercury lamp, thereby forming a red light reflective layer (fifth layer) made of a cholesteric liquid crystal layer. In all cases, light was irradiated from the cholesteric liquid crystal layer side. The coating thickness was adjusted so that the red light reflective layer after curing had a thickness of 3.5 μm.

[0112] The reflection center wavelength and film thickness of each of the cholesteric liquid crystal layers (first to fifth layers) of the produced reflective circular polarizer 1 are shown in Table 4 below. Here, the central reflection wavelength is used to define the characteristics of a light-reflecting film with a reflection band that uses cholesteric liquid crystals, and refers to the midpoint of the spectral band that the film reflects. Specifically, it was obtained by calculating the average value of the wavelengths on the short wavelength side and the long wavelength side that show half the peak reflectance. The central reflection wavelength (the central wavelength of the reflected light) was confirmed by creating a film coated with only a single layer. The film thickness was confirmed using a scanning electron microscope (SEM).

[0113] Table 4. Properties of the light-reflecting layer of reflective circular polarizers [Table 4]

[0114] [Fabrication of reflective circular polarizer 2] Reflective circular polarizer 2 was produced in the same manner as reflective circular polarizer 1, except that a photo-alignment film was formed by the following method.

[0115] <Formation of photo-alignment film> The same temporary support as that for Reflective Circular Polarizer 1 was prepared. The following alignment film forming coating solution PA-2 was applied to the temporary support using a wire bar, and then dried with hot air at 120° C. for 60 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm 2 , irradiation amount 100mJ / cm 2The film was cured by irradiating it with ultraviolet light. This ultraviolet light was passed through a long-pass filter with a transmission band of wavelengths of 340 nm or more. The thickness of the cured coating film was 80 nm. Next, the cured coating was exposed to an illuminance of 7mW / cm 2 , irradiation dose 7.9mJ / cm 2 A photo-alignment film was formed by irradiating the alignment film side with linearly polarized ultraviolet light (wavelength 313 nm). Linearly polarized ultraviolet light with a wavelength of 313 nm was obtained by passing ultraviolet light emitted from a mercury lamp through a bandpass filter with a transmission band at 313 nm and a wire grid polarizer.

[0116] ---------------------------------------------------------------------------------- (Alignment layer forming coating solution PA-2) ---------------------------------------------------------------------------------- 100.00 parts by mass of the following polymer M-PA-2 5.00 parts by mass of the following photopolymerization initiator C n-Butyl acetate 2625.00 parts by mass ----------------------------------------------------------------------------------

[0117] Polymer M-PA-2 [ka]

[0118] Photopolymerization initiator C [ka]

[0119] [Fabrication of reflective circular polarizer 3] A photo-alignment film was formed in the same manner as in the reflective circular polarizer 2. The coating liquid for reflective layer R-1 was applied to the formed photo-alignment film using a wire bar coater, and then dried. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm 2 , irradiation amount 600mJ / cm 2 The coating was cured by irradiating it with light from a high-pressure mercury lamp through a long-pass filter with a transmission band of wavelengths of 340 nm or more, thereby forming a first blue-light reflective layer (first layer) made of a cholesteric liquid crystal layer. Thereafter, the second layer (second blue light reflecting layer) to the fifth layer (red light reflecting layer) were formed in the same manner as in the reflective circular polarizer 1, thereby producing a reflective circular polarizer 3.

[0120] [Fabrication of reflective circular polarizer 4] A photo-alignment film was formed in the same manner as in the reflective circular polarizer 2. The coating liquid for reflective layer R-1 was applied to the formed photo-alignment film using a wire bar coater, and then dried. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm 2 , irradiation amount 600mJ / cm 2 The coating was cured by irradiating it with light from an LED lamp (center wavelength 365 nm), thereby forming a first blue light reflective layer (first layer) made of a cholesteric liquid crystal layer. Thereafter, the second layer (second blue light reflecting layer) to the fifth layer (red light reflecting layer) were formed in the same manner as in the reflective circular polarizer 1, thereby producing a reflective circular polarizer 4.

[0121] [Preparation of reflective circular polarizer 5] A photo-alignment film was formed in the same manner as in the reflective circular polarizer 4, except that the following alignment film-forming coating liquid PA-3 was used as the alignment film-forming coating liquid. Polymerizable monomer E2 has a ClogP value difference of 0.9 from that of PET and a molecular weight of 352, and functions as a polymerizable monomer for PET. The ClogP value of polymerizable monomer E2 is 3.5, while the ClogP value of PET is 2.6. Thereafter, the first layer (first blue light reflecting layer) to the fifth layer (red light reflecting layer) were formed in the same manner as in the reflective circular polarizer 4, thereby producing a reflective circular polarizer 5.

[0122] ---------------------------------------------------------------------------------- (Alignment film forming coating solution PA-3) ---------------------------------------------------------------------------------- ·Polymer M-PA-2 80.00 parts by mass 20.00 parts by mass of the following polymerizable monomer E2 Photopolymerization initiator C 5.00 parts by mass n-Butyl acetate 2625.00 parts by mass ----------------------------------------------------------------------------------

[0123] Polymerizable Monomer E2 [ka]

[0124] [Measurement of peel load for reflective circular polarizers 1 to 5] For the reflective circular polarizers 1 to 5, the peel load (N / inch) of the PET film serving as the temporary support was measured. Specifically, the prepared reflective circular polarizer was cut into a 150 × 25 mm strip, and the surface of the reflective circular polarizer opposite to the temporary support was fixed to a stage with an adhesive (NCF-D692, 15 μm thick, manufactured by Lintec Corporation). From this state, the temporary support was peeled in a 180° direction at a speed of 5 m / min in an environment at a temperature of 25° C. The peel load was measured. The temporary support was peeled in a direction of 150 mm length. The peel load was measured using a digital force gauge RZ-1 manufactured by Aiko Engineering Co., Ltd. The peel load was the average value of two measurements.

[0125] The properties of the produced reflective circular polarizers 1 to 5 are shown in Table 5 below. Table 5. Characteristics of the fabricated reflective circular polarizers 1 to 5 [Table 5]

[0126] [Preparation of Optical Laminates 1 to 5] An optical laminate was produced in the following manner. <Preparation of Retardation Layer> A reverse dispersion retardation layer was produced with reference to the method described in paragraphs 0151 to 0163 of JP 2020-084070 A. The retardation layer 1 had Re(550)=146 nm and Rth(550)=73 nm.

[0127] <Preparation of positive C plates> A positive C plate was prepared by adjusting the film thickness with reference to the method described in paragraphs 0132 to 0134 of JP 2016-053709 A. However, the temporary support was changed from a polyethylene terephthalate film (PET film) to a triacetyl cellulose film (TAC film). The positive C-plate had Re(550)=0.1 nm and Rth(550)=-80 nm.

[0128] <Fabrication of linear polarizer> A linear polarizer was prepared by the following procedure. (Preparation of Cellulose Acylate Film) -Preparation of cellulose acylate dope for core layer- The following composition was charged into a mixing tank and stirred to dissolve each component, thereby preparing a cellulose acetate solution to be used as a cellulose acylate dope for the core layer. ---------------------------------------------------------------------------------- Core layer: cellulose acylate dope ---------------------------------------------------------------------------------- 100 parts by mass of cellulose acetate with an acetyl substitution degree of 2.88 In the example of JP 2015-227955 A 12 parts by weight of the described polyester compound B 2 parts by mass of the following compound F Methylene chloride (first solvent) 430 parts by mass Methanol (second solvent) 64 parts by weight ----------------------------------------------------------------------------------

[0129] Compound F [ka]

[0130] -Preparation of outer layer cellulose acylate dope- To 90 parts by weight of the above-mentioned cellulose acylate dope for the core layer, 10 parts by weight of the following matting agent solution was added to prepare a cellulose acetate solution to be used as the cellulose acylate dope for the outer layer.

[0131] ---------------------------------------------------------------------------------- Matting agent solution ---------------------------------------------------------------------------------- Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride (first solvent) 76 parts by mass Methanol (second solvent) 11 parts by mass 1 part by mass of the above-mentioned cellulose acylate dope for the core layer ----------------------------------------------------------------------------------

[0132] -Preparation of cellulose acylate film- The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm, and then the core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides were simultaneously cast onto a drum at 20°C from a casting nozzle (band casting machine). Next, the film was peeled off when the solvent content was about 20% by mass, and both ends in the width direction of the film were fixed with tenter clips, and the film was dried while being stretched in the transverse direction at a stretch ratio of 1.1. Thereafter, the film was further dried by conveying it between rolls of a heat treatment device to prepare an optical film having a thickness of 40 μm, which was used as a cellulose acylate film. The in-plane retardation of the obtained cellulose acylate film was 0 nm.

[0133] <Formation of photo-alignment film PA3>

[0134] Using the prepared cellulose acylate film as a support, the following coating liquid for forming an alignment film, S-PA-3, was continuously coated onto the support with a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds, and then the coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 By using an ultra-high pressure mercury lamp, a photo-alignment film PA3 was formed. The film thickness was 0.3 μm.

[0135] ---------------------------------------------------------------------------------- (Alignment film forming coating liquid S-PA-3) ---------------------------------------------------------------------------------- 100.00 parts by mass of the above polymer M-PA-1 5.00 parts by weight of the acid generator PAG-1 0.005 parts by weight of the acid generator CPI-110TF Xylene 1220.00 parts by mass Methyl isobutyl ketone 122.00 parts by mass ----------------------------------------------------------------------------------

[0136] (Formation of optically absorbing anisotropic layer) On the formed photo-alignment film PA3, the following coating solution for forming an optically absorptive anisotropic layer was continuously coated with a wire bar. The coated layer was then heated at 140° C. for 30 seconds and cooled to room temperature (23° C.), then heated at 90° C. for 60 seconds and cooled again to room temperature. Then, an LED lamp (center wavelength 365 nm) was used to illuminate the specimen at an intensity of 200 mW / cm 2 An optically absorptive anisotropic layer was formed on the alignment film PA3 by irradiating the film for 2 seconds under the irradiation conditions of 1.6 μm. The thickness of the optically absorptive anisotropic layer was 1.6 μm. In this way, a linear polarizer was produced. In this linear polarizer, the cellulose acylate film serves as a temporary support, that is, the linear polarizer is formed by the photo-alignment film PA3 and the light absorption anisotropic layer.

[0137] ---------------------------------------------------------------------------------- Composition of coating solution for forming optically absorbing anisotropic layer ---------------------------------------------------------------------------------- 0.25 parts by weight of the following dichroic substance D-1 0.36 parts by weight of the following dichroic substance D-2 0.59 parts by weight of the following dichroic substance D-3 2.21 parts by weight of the following polymer liquid crystal compound MP-1 1.36 parts by mass of the following low molecular weight liquid crystal compound M-1 Polymerization initiator IRGACURE OXE-02 (BASF) 0.200 parts by mass 0.026 parts by mass of the following surfactant F-3 Cyclopentanone 46.00 parts by mass Tetrahydrofuran 46.00 parts by mass Benzyl alcohol 3.00 parts by mass ----------------------------------------------------------------------------------

[0138] Dichroic substance D-1 [ka]

[0139] Dichroic substance D-2 [ka]

[0140] Dichroic substance D-3 [ka]

[0141] Polymer liquid crystal compound MP-1 [ka]

[0142] Low molecular liquid crystal compound M-1 [ka]

[0143] Surfactant F-3 [ka]

[0144] <Transfer for producing optical laminate> The transfer for producing the optical laminate was carried out according to the following procedure. (1) A UV adhesive Chemiseal U2084B (manufactured by Chemittech, refractive index after curing: n 1.60) was applied to a PMMA (polymethyl methacrylate) substrate using a wire bar coater to a thickness of 2 μm. A linear polarizer was laminated on the UV adhesive using a laminator so that the side opposite to the temporary support, i.e., the optically absorptive anisotropic layer, was in contact with the UV adhesive. (2) Nitrogen was purged in the purge box until the oxygen concentration was 100 ppm or less. After that, ultraviolet light from a high-pressure mercury lamp was irradiated from the temporary support side of the linear polarizer to cure the UV adhesive. The irradiance was 25 mW / cm. 2 , the irradiation dose is 1000mJ / cm 2 It was decided. (3) Finally, the temporary support (cellulose acylate film) was peeled off to produce a laminate consisting of the linear polarizer (light absorption anisotropic layer and photo-alignment film PA3), the UV adhesive, and the PMMA substrate.

[0145] Next, the retardation layer was transferred onto the linear polarizer using the same transfer procedure as above. The transfer was performed so that the angle between the slow axis of the laminated retardation layer and the absorption axis of the linear polarizer was 45°. Next, a positive C plate was transferred onto the retardation layer using the same transfer procedure as above. Finally, reflective circular polarizer 1 was transferred to the positive C plate using the same transfer procedure as above. Note that the temporary support for reflective circular polarizer 1 was only a PET film, so reflective circular polarizer 1 was composed of a photo-alignment film and five cholesteric liquid crystal layers. In this manner, an optical laminate 1 using the reflective circular polarizer 1 of Example 1 was obtained. That is, the optical laminate 1 is composed of a linear polarizer, a retardation layer, a positive C plate, and a reflective circular polarizer (cholesteric liquid crystal layer / photo-alignment film).

[0146] Regarding the reflective circular polarizers 2 to 5, optical laminates 2 to 5 were also produced in the same manner.

[0147] [Forming method] The produced optical laminate was molded into a curved surface shape. The optical laminate 1 was set in a molding device. The molding space in the molding device consisted of box 1 and box 2, separated by optical laminate 1. A convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm, radius of curvature of concave surface 65 mm) manufactured by Thorlab, with aluminum vapor deposition on the convex surface, was placed as a mold in box 1 below optical laminate 1, with the concave surface facing up. In this case, the reflective circular polarizer side of optical laminate 1 was placed on the mold side. A transparent window was provided at the top of the box 2 above the optical laminate 1, and an IR light source for heating the optical laminate 1 was installed outside the window. A patterned infrared reflection filter consisting of a cholesteric liquid crystal layer that reflects infrared rays with wavelengths of 2.2 μm to 3.0 μm at a reflectance of approximately 50% was placed between the infrared light source and the optical laminate 1. The patterned infrared reflection filter had a donut shape, with a 1-inch diameter hole cut out in the center of a circular infrared reflection filter with a diameter of 2 inches. The patterned infrared reflection filter was placed so that the center of the patterned infrared reflection filter was at the center of the mold when viewed from directly above. Next, the inside of box 1 and the inside of box 2 were evacuated to a vacuum of 0.1 atmospheres or less using a vacuum pump. Next, in the step of heating the optical laminate 1, infrared rays were irradiated and the optical laminate 1 was heated until the center reached 108°C and the edges reached 99°C. Because the glass transition temperature Tg of the PMMA film used as the support was 105°C, the aim was to create a state in which the center would easily stretch and the edges would not easily stretch during molding. Next, in a step of pressing the optical laminate 1 against the mold and deforming it to fit the shape of the mold, gas was flowed into the box 2 from a gas cylinder to pressurize it to 300 kPa, and the optical laminate 1 was pressure-bonded to the mold. Finally, the optical laminate 1 was removed from the lens mold. This resulted in an optical laminate 1 molded to a curved surface.

[0148] Optical laminates 2 to 5 were also molded into curved surfaces using the same procedure.

[0149] [Creating a virtual reality display device] We disassembled the Huawei VR Glass, a virtual reality display device made by Huawei that uses a reciprocating optical system, and removed all of the compound lenses. Instead, a composite lens 1 corresponding to the composite lens removed from the virtual reality display device was prepared by bonding the prepared optical laminate 1. The optical laminate 1 was bonded using an adhesive (NCF-D692, manufactured by Lintec Corporation). The optical laminate 1 was attached so that the linear polarizer was located on the outer side of the compound lens 1. That is, the optical laminate 1 was attached so that the photo-alignment film was on the lens side of the compound lens 1. The virtual reality display device of Example 1 was fabricated by placing this compound lens 1 on the main body of the virtual reality display device from which the compound lens had been removed, with the linear polarizer facing the user.

[0150] Furthermore, for the optical laminates 2 to 5, composite lenses 2 to 5 were produced in the same manner as in Example 1 and incorporated into the main body of the virtual reality display device to produce the virtual reality display devices of Comparative Example 1 and Examples 2 to 4.

[0151] [Evaluation of image distortion] In the prepared virtual reality display device, a black and white checkered pattern was displayed on the image display panel, and image distortion was visually evaluated on the following four-point scale. A: No distortion is visible. B: There is a slight distortion, but it is not noticeable. C: Weak distortion is visible. D: Strong distortion is visible. The evaluation results are shown in Table 6 below.

[0152] Table 6. Reflective circular polarizers used in the examples and comparative examples, and evaluation results of image distortion [Table 6]

[0153] As shown in Table 6, the virtual reality display devices of Examples 1 to 3 incorporating laminated optical films prepared using reflective circular polarizers corresponding to the transfer films of the present invention, in which the peel load of the temporary support is 0.20 N / inch or less, exhibited little image distortion. In particular, in Examples 2, 3, and 4, in which the peel load of the temporary support is 0.10 N / inch or less, no image distortion was observed. In contrast to this, in Comparative Example 1, in which the peel load of the temporary support exceeded 0.20 N / inch, image distortion was observed. From the above results, the effects of the present invention are clear. [Industrial Applicability]

[0154] The present invention can be suitably used in virtual image display devices such as virtual reality display devices. [Explanation of symbols]

[0155] 10 Transfer film 12 Temporary support 14 Photo-alignment film 16, 128 Cholesteric liquid crystal layer 20 Optical laminate 24, 120 Linear polarizer 26, 118 Retardation layer 28, 116 Reflective circular polarizer 32, 112 Half mirror 34, 114 Lens substrate 40, 100 Virtual reality display device 42, 102 image display panel 46, 50, 104, 108 λ / 4 wave plate 48, 106 Linear polarizer 118 λ / 4 plate 124 Support 126 Alignment film

Claims

1. A temporary support; a photo-alignment film disposed in contact with the temporary support; a cholesteric liquid crystal layer disposed in contact with the photo-alignment film, the temporary support is a polyester film, A transfer film in which the peel load between the temporary support and the photo-alignment film is 0.20 N / inch or less.

2. 2. The transfer film according to claim 1, wherein a peel load between the temporary support and the photo-alignment film is 0.05 to 0.20 N / inch.

3. The transfer film according to claim 1 , wherein the photo-alignment film comprises a polymer of a compound having a photo-alignment group and a radical polymerizable group.

4. The transfer film according to claim 1 , wherein the photo-alignment film contains a polymerizable monomer having a difference in ClogP value between the polymerizable monomer and a material forming the temporary support of 3.0 or less in absolute value.

5. The transfer film according to claim 1 , wherein the cholesteric liquid crystal layer has a thickness of 10 μm or more.

6. An optical laminate produced using the transfer film according to any one of claims 1 to 5.

7. A virtual image display device comprising the optical laminate according to claim 6 .

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