Display Set

Abstract

A display medium that comprises: a multilayer substrate comprising a polarization separation layer and a phase difference layer; and a first reflective layer provided on a surface on the polarization separation layer side of the multilayer substrate. The polarization separation layer reflects circular polarization light in one rotation direction DA and can transmit circular polarization light in the opposite rotation direction. The first reflective layer reflects circular polarization light in one rotation direction DB1 and can transmit circular polarization light in the opposite rotation direction. The rotation direction DA of the circular polarization light that the polarization separation layer can reflect is the same as the rotation direction DB1 for circular polarization light that the first reflective layer can reflect.

Description

[Technical field]

[0001] The present invention relates to a display medium, a display article to be viewed through the display medium, and a display set including a combination thereof. [Background technology]

[0002] A circular polarizing plate generally has a function of selectively transmitting either circularly polarized light having a clockwise rotation direction (i.e., right-handed circularly polarized light) or circularly polarized light having a counterclockwise rotation direction (i.e., left-handed circularly polarized light). Utilizing this function, circular polarizing plates have been used in the past for authenticity identification purposes (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5828182 [Patent Document 2] Patent No. 3652476 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors considered that the function of the circularly polarizing plate could be utilized for applications other than the identification of authenticity, and attempted to create a new display mode.

[0005] The present invention has been devised in view of the above problems, and has an object to provide a display set that can realize a new display mode that has not been seen before, as well as a display medium and a display article that can be applied to the display set. [Means for solving the problem]

[0006] The present inventor has conducted intensive research to solve the above-mentioned problems. As a result, the present inventor has found that a display set including a display medium including a multilayer substrate having a polarized light separation layer and a retardation layer having a circularly polarized light separation function and a reflective layer having a specific circularly polarized light separation function provided on the surface of the multilayer substrate, and a display product including a base product and a display layer having a circularly polarized light separation function, can solve the above-mentioned problems, and has completed the present invention. That is, the present invention includes the following.

[0007] [1] A multilayer substrate having a polarization separation layer and a retardation layer, and a first reflective layer provided on a surface of the multilayer substrate facing the polarization separation layer, The polarization separation layer has a rotation direction D A It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The first reflective layer is oriented in one rotation direction D B1 It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The direction of rotation of the circularly polarized light that the polarization separation layer can reflect is D A and the rotation direction D of the circularly polarized light that the first reflective layer can reflect. B1 The same is true for the display medium. [2] A second reflective layer is provided on the retardation layer side of the multilayer base material, The second reflective layer is oriented in one rotation direction D B2 It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The direction of rotation of the circularly polarized light that the polarization separation layer can reflect is D A and the rotation direction D of the circularly polarized light that the second reflective layer can reflect. B2 The display medium according to [1], wherein the above is reversed. [3] A multilayer base material including a polarization separation layer and a retardation layer, and a second reflective layer provided on a surface of the multilayer base material on the retardation layer side, The polarization separation layer has a rotation direction D A It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The second reflective layer is oriented in one rotation direction D B2It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The direction of rotation of the circularly polarized light that the polarization separation layer can reflect is D A and the rotation direction D of the circularly polarized light that the second reflective layer can reflect. B2 However, the opposite is true for display media. [4] The display medium according to [1] or [2], wherein the first reflective layer contains flakes of a resin having cholesteric regularity. [5] The display medium according to [2] or [3], wherein the second reflective layer contains flakes of a resin having cholesteric regularity. [6] The display medium according to any one of [1] to [5], wherein the in-plane retardation of the retardation layer at a measurement wavelength of 590 nm is from "{(2n+1) / 2}×590 nm-30 nm" to "{(2n+1) / 2}×590 nm+30 nm" (wherein n is an integer of 0 or more). [7] The display medium according to any one of [1] to [6], wherein the wavelength width of the wavelength range in which the polarization separation layer can reflect circularly polarized light is 70 nm or more. [8] The display medium according to any one of [1] to [7], wherein the polarization separation layer is a layer of a resin having cholesteric regularity. [9] A display article to be observed through the display medium according to any one of [1] to [8], The display article comprises a base article and a display layer provided on the base article, The display layer rotates in one direction D D A display article capable of reflecting circularly polarized light of one direction and transmitting circularly polarized light of the opposite rotation direction.

[10] As a display layer, The direction of rotation of the circularly polarized light that the polarization separation layer can reflect is D A Same rotation direction as D D1 a first display layer that reflects circularly polarized light having a rotation direction of 1 and transmits circularly polarized light having an opposite rotation direction; The direction of rotation of the circularly polarized light that the polarization separation layer can reflect is D A and the opposite rotation direction D D2and a second display layer capable of reflecting circularly polarized light having the opposite rotation direction and transmitting circularly polarized light having the opposite rotation direction.

[11] A display set comprising the display medium according to any one of [1] to [8] and the display article according to [9] or

[10] . Effect of the Invention

[0008] According to the present invention, it is possible to provide a display set capable of realizing a new display mode not seen before, as well as a display medium and a display article applicable to the display set. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating a display medium according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view of the display medium according to the first embodiment of the present invention as viewed from one side (the side on which the first reflective layer is provided). [Diagram 3] FIG. 3 is a schematic plan view of the display medium according to the first embodiment of the present invention as viewed from the other side (the side opposite to where the first reflective layer is provided). [Figure 4] FIG. 4 is a cross-sectional view illustrating a display medium according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view illustrating a display medium according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view illustrating a display medium according to a second embodiment of the present invention. [Figure 7] FIG. 7 is a schematic plan view of a display medium according to a second embodiment of the present invention, as viewed from one side (the side opposite to the side where the second reflective layer is provided). [Figure 8] FIG. 8 is a schematic plan view of the display medium according to the second embodiment of the present invention as viewed from the other side (the side on which the second reflective layer is provided). [Figure 9] FIG. 9 is a cross-sectional view illustrating a display medium according to the second embodiment of the present invention. [Figure 10]FIG. 10 is a cross-sectional view that illustrates a display medium according to the second embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view that illustrates a display medium according to a third embodiment of the present invention. [Figure 12] FIG. 12 is a schematic plan view of a display medium according to a third embodiment of the present invention, as viewed from one side (the side on which the first reflective layer is provided). [Figure 13] FIG. 13 is a schematic plan view of the display medium according to the third embodiment of the invention as viewed from the other side (the side on which the second reflective layer is provided). [Figure 14] FIG. 14 is a cross-sectional view that illustrates a display set according to a fourth embodiment of the present invention. [Figure 15] FIG. 15 is a cross-sectional view that typically shows a display article included in a display set according to a fourth embodiment of the present invention. [Figure 16] FIG. 16 is a plan view that illustrates a display article included in a display set according to a fourth embodiment of the present invention. [Figure 17] FIG. 17 is a plan view that shows a schematic image visually recognized when the display set shown in FIG. 14 is observed from above in the figure. [Figure 18] FIG. 18 is a cross-sectional view that illustrates a display set according to a fourth embodiment of the present invention. [Figure 19] FIG. 19 is a plan view that shows a schematic image visually recognized when the display set shown in FIG. 18 is observed from above in the figure. [Figure 20] FIG. 20 is a cross-sectional view that illustrates the display set produced in Example 1. As shown in FIG. [Figure 21] FIG. 21 is a cross-sectional view that illustrates the display set produced in Example 2. As shown in FIG. [Figure 22] FIG. 22 is a cross-sectional view that illustrates the display set produced in Comparative Example 1. As shown in FIG. [Figure 23] FIG. 23 is a cross-sectional view that illustrates the display set produced in Comparative Example 2. As shown in FIG. [Figure 24] FIG. 24 is a cross-sectional view that illustrates the display set produced in Comparative Example 3. As shown in FIG. [Diagram 25]FIG. 25 is a cross-sectional view that illustrates the display set produced in Comparative Example 4. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be modified and implemented as desired without departing from the scope of the claims of the present invention and their equivalents.

[0011] In the following description, the in-plane retardation Re of a layer is a value expressed by Re=(nx-ny)×d, unless otherwise specified. Here, nx represents the refractive index in a direction perpendicular to the thickness direction of the layer (in-plane direction) that gives the maximum refractive index. ny represents the refractive index in the in-plane direction perpendicular to the direction of nx. nz represents the refractive index in the thickness direction. d represents the thickness of the layer. The measurement wavelength is 590 nm, unless otherwise specified.

[0012] In the following description, "circularly polarized light" also includes elliptically polarized light as long as the effects of the present invention are not significantly impaired.

[0013] [1. Overview of display sets] A display set according to an embodiment of the present invention includes a display medium and a display article. The display medium includes a multilayer substrate including a polarization separation layer and a retardation layer, and a reflective layer such as a first reflective layer and a second reflective layer provided on at least one surface of the multilayer substrate. The display article includes a base article and a display layer provided on the base article.

[0014] The multi-layer substrate of the display medium can transmit a part of the irradiated light such as unpolarized light including both right-handed and left-handed circularly polarized light. Specifically, the polarization separation layer of the multi-layer substrate can transmit a part of the irradiated light in one of the clockwise and counterclockwise rotation directions D A The multi-layer substrate can reflect circularly polarized light of one direction and transmit circularly polarized light of the opposite direction. Therefore, the multi-layer substrate can be a member that is transparent or semi-transparent to the irradiated light.

[0015] Furthermore, the reflective layer of the display medium is rotatable in one of the clockwise and counterclockwise directions D B The reflector 14 is provided so as to reflect circularly polarized light having a rotation direction of 1 and transmit circularly polarized light having the opposite rotation direction.

[0016] Specifically, the first reflective layer provided on the surface of the multilayer substrate facing the polarization separation layer can reflect the circularly polarized light in the direction of rotation D. B1 is the rotation direction D of the circularly polarized light that the polarization separation layer can reflect. A Unless otherwise specified, the "surface on the polarization separation layer side of the multilayer substrate" refers to the surface of the front surface or back surface of the multilayer substrate that is closer to the polarization separation layer than to the retardation layer. As a result, even when light passes through the multilayer substrate and enters the first reflective layer, the rotation direction D of at least a part of the circularly polarized light contained in the light is C and the rotation direction D of the circularly polarized light that the first reflective layer can reflect. B1 The opposite is true.

[0017] In addition, the rotation direction D of the circularly polarized light that can be reflected by the second reflective layer provided on the retardation layer side of the multilayer base material B2 is the rotation direction D of the circularly polarized light that the polarization separation layer can reflect. A Unless otherwise specified, the term "surface of the retardation layer of the multilayer substrate" refers to the surface of the front surface or the back surface of the multilayer substrate that is longer than the distance to the polarization separation layer. As a result, even when light passes through the multilayer substrate and enters the second reflective layer, the rotation direction D of at least a part of the circularly polarized light contained in the light is C and the rotation direction D of the circularly polarized light that the second reflective layer can reflect. B2 The opposite is true.

[0018] In this case, in both the first reflective layer and the second reflective layer, when light passes through the multilayer substrate and enters the reflective layer, some or all of the light is not reflected by the reflective layer.

[0019] Therefore, when the display medium is observed from the reflective layer side, strong light reflection occurs at the reflective layer, so the reflective layer can be seen, but when the display medium is observed from the opposite side to the reflective layer, no light is reflected at the reflective layer or the reflection is weak, so the reflective layer cannot be seen. Therefore, when the display medium is observed under light containing both right-handed and left-handed circularly polarized light, even though the multilayer base material is transparent or translucent, the image of the display medium seen when observed from the front side may differ from the image of the display medium seen when observed from the back side.

[0020] In addition, under irradiation light including both right-handed and left-handed circularly polarized light, the multilayer substrate is transparent or semi-transparent as described above, so that at least a part of the display medium can also be transparent or semi-transparent. Therefore, the observer can observe the display article through the display medium. Here, the retardation layer provided in the multilayer substrate changes the polarization state of the light passing through the retardation layer, so that the rotation direction of the circularly polarized light blocked by the multilayer substrate can differ depending on the traveling direction of the circularly polarized light. For example, when the right-handed circularly polarized light irradiated to the front surface of the multilayer substrate is blocked by the multilayer substrate, the multilayer substrate can block the left-handed circularly polarized light irradiated to the back surface of the multilayer substrate. Therefore, the display medium can switch between right-handed circularly polarized light and left-handed circularly polarized light depending on the orientation of the front and back.

[0021] The display layer of the display article is provided so as to reflect circularly polarized light having a specific rotation direction and transmit circularly polarized light having the opposite rotation direction. Therefore, depending on the orientation of the display medium, the circularly polarized light reflected by the display layer may or may not be blocked by the display medium. Therefore, when the display article is observed through the display medium, the image of the display article visually recognized when observed from the front side may differ from the image of the display article visually recognized when observed from the back side.

[0022] In this way, in the display set according to the present embodiment, the image of the display medium and the image of the display article that are viewed can both be different depending on the orientation of the display medium. Therefore, by combining different images in this way, it is possible to realize complementary designs, achieving new display modes that have not been seen before, and ultimately creating complex and flexible designs.

[0023] [2. First embodiment relating to display medium] Fig. 1 is a cross-sectional view showing a display medium 100 according to a first embodiment of the present invention. Fig. 2 is a schematic plan view showing the display medium 100 according to the first embodiment of the present invention as viewed from one side (the side on which the first reflective layer 120 is provided). Fig. 3 is a schematic plan view showing the display medium 100 according to the first embodiment of the present invention as viewed from the other side (the side opposite to the side on which the first reflective layer 120 is provided).

[0024] As shown in Figures 1 to 3, the display medium 100 according to the first embodiment of the present invention comprises a multilayer substrate 110 and a first reflective layer 120 as a reflective layer provided on a surface 110U of the multilayer substrate 110 facing the polarization separation layer.

[0025] The multilayer substrate 110 includes a polarization separation layer 111 and a retardation layer 112 .

[0026] The polarization separation layer 111 has a circular polarization separation function. The "circular polarization separation function" means a function of reflecting circularly polarized light having one of the rotation directions, clockwise and counterclockwise, and transmitting circularly polarized light having the opposite rotation direction. Therefore, the polarization separation layer 111 reflects circularly polarized light having one of the rotation directions D in the wavelength range in which the circular polarization separation function can be exerted. A The circularly polarized light is reflected and rotated in the direction D. A It can transmit circularly polarized light having the opposite rotation direction to that of the polarized light separating layer 111. In the following description, the wavelength range in which the polarized light separating layer 111 can exhibit the circularly polarized light separating function is sometimes referred to as the "polarized light separating wavelength range" as appropriate. The reflectance of the polarized light separating layer 111 to unpolarized light in the polarized light separating wavelength range is usually 35% to 50%, and preferably 40% to 50%.

[0027] From the viewpoint of realizing a display mode that can be seen by the naked eye, the polarization separation wavelength range is preferably in the visible wavelength region, which generally refers to a wavelength range of 400 nm or more and 780 nm or less.

[0028] The wavelength width of the polarization separation wavelength range is preferably wide. The specific wavelength width of the polarization separation wavelength range is preferably 70 nm or more, more preferably 100 nm or more, even more preferably 200 nm or more, and particularly preferably 400 nm or more. Since the wavelength width of the polarization separation wavelength range is wide, the range of colors of the circularly polarized light that can be reflected by the polarization separation layer 111 can be widened, so that the color freedom of the reflective layers such as the first reflective layer 120 and the display layer of the display article (not shown in Figs. 1 to 3) can be increased, and a display mode with high designability can be achieved. The upper limit of the wavelength width of the polarization separation wavelength range is not particularly limited, but can be, for example, 600 nm or less.

[0029] The polarization separation layer 111 is preferably a layer of a resin having cholesteric regularity. Hereinafter, a resin having cholesteric regularity may be referred to as a "cholesteric resin" as appropriate. Cholesteric regularity is a structure in which the molecular axes are aligned in a certain direction on a certain plane, but the direction of the molecular axes is shifted at a slight angle on the next plane that overlaps it, and the angle is shifted further on the next plane, and so on, such that the angle of the molecular axes in the plane is shifted (twisted) as the light passes through the overlapping and arranged planes one after another. That is, when molecules inside a certain layer have cholesteric regularity, the molecules are aligned so that the molecular axes are in a certain direction on a first plane inside the layer. On a second plane that overlaps the first plane inside the layer, the direction of the molecular axes is shifted at a slight angle from the direction of the molecular axes on the first plane. On a third plane that further overlaps the second plane, the direction of the molecular axes is shifted at a further angle from the direction of the molecular axes on the second plane. In this way, in the planes where the molecules are arranged in an overlapping manner, the angles of the molecular axes in the planes are gradually shifted (twisted). A structure in which the directions of the molecular axes are twisted in this way is usually a helical structure, which is an optically chiral structure.

[0030] Generally, a layer of a cholesteric resin can exhibit a circularly polarized light separation function, in that the layer of the cholesteric resin reflects circularly polarized light while maintaining its chirality.

[0031] The specific wavelength at which the cholesteric resin layer exhibits the circularly polarized light separation function generally depends on the pitch of the helical structure in the cholesteric resin layer. The pitch of the helical structure is the distance in the plane normal direction from the angle of the molecular axis direction in the helical structure as it progresses along the plane to the original molecular axis direction. The wavelength at which the circularly polarized light separation function is exhibited can be changed by changing the pitch of the helical structure. For example, the method described in JP-A-2009-300662 can be used as a method for adjusting the pitch. Specific examples include a method of adjusting the type of chiral agent or the amount of chiral agent in a cholesteric liquid crystal composition. In particular, if the pitch of the helical structure changes continuously within the layer, a single cholesteric resin layer can obtain a circularly polarized light separation function over a wide wavelength range.

[0032] Examples of cholesteric resin layers capable of exhibiting circularly polarized light separation function over a wide wavelength range include (i) cholesteric resin layers in which the pitch of the helical structure is changed in stages, and (ii) cholesteric resin layers in which the pitch of the helical structure is changed continuously.

[0033] (i) A layer of a cholesteric resin with a stepwise change in the pitch of the helical structure can be obtained, for example, by laminating a plurality of cholesteric resin layers with different pitches of the helical structure. The lamination can be performed by first preparing a plurality of cholesteric resin layers with different pitches of the helical structure, and then fixing each layer with a pressure sensitive adhesive or a bonding agent. Alternatively, the lamination can be performed by forming a layer of a certain cholesteric resin, and then sequentially forming layers of another cholesteric resin on the layer.

[0034] (ii) A cholesteric resin layer in which the pitch of the helical structure is continuously changed can be obtained, for example, by subjecting a liquid crystal composition layer to a band-broadening treatment including one or more irradiation treatments with active energy rays and / or heating treatments, and then curing the liquid crystal composition layer. The band-broadening treatment allows the pitch of the helical structure to be continuously changed in the thickness direction, thereby expanding the wavelength range (reflection band) in which the cholesteric resin layer can exhibit the circularly polarized light separation function, and is therefore called a band-broadening treatment.

[0035] The cholesteric resin layer may be a single-layer structure consisting of only one layer, or may be a multi-layer structure consisting of two or more layers. From the viewpoint of ease of production, the number of layers included in the cholesteric resin layer is preferably 1 to 100, and more preferably 1 to 20.

[0036] There is no limitation on the manufacturing method of the cholesteric resin layer, but it can usually be manufactured using a cholesteric liquid crystal composition. The cholesteric liquid crystal composition refers to a composition that can exhibit a liquid crystal phase (cholesteric liquid crystal phase) with cholesteric regularity when the liquid crystal compound contained in the liquid crystal composition is aligned. Here, for convenience, the material referred to as "liquid crystal composition" includes not only a mixture of two or more substances but also a material consisting of a single substance. Specific methods for manufacturing the cholesteric resin layer include, for example, the methods described in JP-A-2014-174471 and JP-A-2015-27743. In such a manufacturing method using a cholesteric liquid crystal composition, the twist direction in the cholesteric regularity can be appropriately selected depending on the structure of the chiral agent contained in the liquid crystal composition. For example, when the twist is right-handed, a cholesteric liquid crystal composition containing a chiral agent that imparts right-handedness can be used, and when the twist direction is left-handed, a cholesteric liquid crystal composition containing a chiral agent that imparts left-handedness can be used.

[0037] The thickness of the polarization separation layer 111 is preferably 2 μm or more, more preferably 3 μm or more, and is preferably 1000 μm or less, more preferably 500 μm or less. When the thickness of the polarization separation layer 111 is equal to or more than the lower limit of the above range, the reflective layer such as the first reflective layer 120 can be made difficult to see when the display medium 100 is observed from the side opposite to where the reflective layer is provided. On the other hand, when the thickness of the polarization separation layer 111 is equal to or less than the upper limit of the above range, the transparency can be increased.

[0038] The retardation layer 112 is a layer having an in-plane retardation Re in a specific range provided on one side of the polarization separation layer 111. A part or the whole of the retardation layer 112 overlaps a part or the whole of the polarization separation layer 111 when viewed from the thickness direction. That is, the position in the in-plane direction perpendicular to the thickness direction of the display medium 100 is the same for a part or the whole of the retardation layer 112 and a part or the whole of the polarization separation layer 111. In this embodiment, an example in which the whole of the retardation layer 112 and the whole of the polarization separation layer 111 overlap when viewed from the thickness direction will be described.

[0039] The range of the in-plane retardation Re of the retardation layer 112 can be set within a range in which a desired design is obtained between an image visually recognized by observing one side of the display medium 100 and an image visually recognized by observing the other side of the display medium 100. Usually, the in-plane retardation Re of the retardation layer 112 is set so as to invert the rotation direction of the circularly polarized light transmitted through the polarization separation layer.

[0040] Specific ranges of the in-plane retardation Re of the retardation layer 112 are preferably "{(2n+1) / 2}×590nm-30nm" or more, more preferably "{(2n+1) / 2}×590nm-20nm" or more, particularly preferably "{(2n+1) / 2}×590nm-10nm" or more, and preferably "{(2n+1) / 2}×590nm+30nm" or less, more preferably "{(2n+1) / 2}×590nm+20nm" or less, particularly preferably "{(2n+1) / 2}×590nm+10nm" or less, at a measurement wavelength of 590nm. Here, n represents an integer of 0 or more. The retardation layer 112 having an in-plane retardation Re in the above range at a measurement wavelength of 590 nm can usually function as a half-wave plate in a wide range of the visible wavelength region, and therefore can appropriately adjust the polarization state of circularly polarized light of a wide range of colors by the retardation layer 112. This increases the degree of freedom in the colors of the reflective layers such as the first reflective layer 120 and the display layer of the display article (not shown in Figs. 1 to 3), enabling a display mode with excellent design.

[0041] The retardation layer 112 preferably has reverse wavelength dispersion. The reverse wavelength dispersion means that the in-plane retardations Re(450) and Re(550) at measurement wavelengths of 450 nm and 550 nm satisfy the following formula (R1). Re(450) <Re(550) (R1) The retardation layer 112 having the reverse wavelength dispersion can exert its optical function in a wide wavelength range. Therefore, by using the retardation layer 112 having the reverse wavelength dispersion, it can function as a half-wave plate in a wide range of the visible wavelength region, and the retardation layer 112 can appropriately adjust the polarization state of circularly polarized light of a wide range of colors. Therefore, the degree of freedom of color of the reflective layers such as the first reflective layer 120 and the display layer of the display article (not shown in Figs. 1 to 3) can be increased, and a display mode with high designability can be realized.

[0042] For example, a stretched film can be used as the retardation layer 112. A stretched film is a film obtained by stretching a resin film, and any in-plane retardation can be obtained by appropriately adjusting factors such as the type of resin, stretching conditions, and thickness. A thermoplastic resin is usually used as the resin. This thermoplastic resin may contain a polymer and any component as necessary. Examples of the polymer include polycarbonate, polyethersulfone, polyethylene terephthalate, polyimide, polymethyl methacrylate, polysulfone, polyarylate, polyethylene, polyphenylene ether, polystyrene, polyvinyl chloride, cellulose diacetate, cellulose triacetate, and alicyclic structure-containing polymers. In addition, the polymer may be used alone or in combination of two or more types at any ratio. Among them, alicyclic structure-containing polymers are preferable from the viewpoints of transparency, low moisture absorption, dimensional stability, and processability. The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the main chain and / or side chain, and for example, those described in JP-A-2007-057971 can be used.

[0043] The stretched film as the retardation layer 112 can be produced by producing a resin film from the above-mentioned resin and then performing a stretching process on the resin film. A specific example of a method for producing the retardation layer 112 as a stretched film is the method described in International Publication No. 2019 / 059067.

[0044] The thickness of the stretched film is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 20 μm or more, and is preferably 1 mm or less, more preferably 500 μm or less, particularly preferably 200 μm or less.

[0045] For example, a liquid crystal cured layer may be used as the retardation layer 112. The liquid crystal cured layer is a layer formed of a cured product of a liquid crystal composition containing a liquid crystal compound. Usually, a liquid crystal cured layer is obtained by forming a layer of the liquid crystal composition, orienting the molecules of the liquid crystal compound contained in the layer of the liquid crystal composition, and then curing the layer of the liquid crystal composition. This liquid crystal cured layer can obtain any in-plane retardation by appropriately adjusting factors such as the type of liquid crystal compound, the alignment state of the liquid crystal compound, and the thickness.

[0046] The type of liquid crystal compound is arbitrary, but when a retardation layer 112 having reverse wavelength dispersion is to be obtained, it is preferable to use a reverse wavelength dispersion liquid crystal compound. The reverse wavelength dispersion liquid crystal compound refers to a liquid crystal compound that exhibits reverse wavelength dispersion when homogeneously aligned. In addition, homogeneously aligning a liquid crystal compound refers to forming a layer containing the liquid crystal compound, and aligning the direction of the maximum refractive index in the refractive index ellipsoid of the molecules of the liquid crystal compound in the layer in a certain direction parallel to the surface of the layer. Specific examples of reverse wavelength dispersion liquid crystal compounds include compounds described in, for example, International Publication No. 2014 / 069515 and International Publication No. 2015 / 064581.

[0047] The thickness of the liquid crystal cured layer is not particularly limited, but is preferably 0.5 μm or more, more preferably 1.0 μm or more, and is preferably 10 μm or less, more preferably 7 μm or less, and particularly preferably 5 μm or less.

[0048] The multilayer substrate 110 may include any layer (not shown) within a range that does not significantly impair the effects of the present invention. Examples of the optional layer include a support layer that supports the polarization separation layer 111 and the retardation layer 112, and an adhesive layer that bonds the polarization separation layer 111 and the retardation layer 112. It is preferable that these optional layers have a small in-plane retardation. The specific in-plane retardation of the optional layer is preferably 20 nm or less, more preferably 10 nm or less, particularly preferably 5 nm or less, and ideally 0 nm. Since the layer having such a small in-plane retardation is an optically isotropic layer, it is possible to suppress the change in the polarization state caused by the optional layer.

[0049] The first reflective layer 120 as a reflective layer is provided on the surface 110U of the multilayer base material 110 on the polarization separation layer side. The first reflective layer 120 may be provided directly or indirectly on the surface 110U of the multilayer base material 110. When a layer is provided "directly" on a surface, it means that there is no other layer between the surface and the layer. When a layer is provided "indirectly" on a surface, it means that there is another layer (such as an adhesive layer) between the surface and the layer.

[0050] The first reflective layer 120 may be provided on a part of the surface 110U of the multilayer substrate 110, or may be provided on the entire surface 110U. Usually, the first reflective layer 120 is provided so as to overlap both the polarization separation layer 111 and the retardation layer 112 of the multilayer substrate 110 when viewed from the thickness direction. That is, the position in the in-plane direction perpendicular to the thickness direction of the display medium 100 is usually the same for the entire first reflective layer 120, a part or the entire retardation layer 112, and a part or the entire polarization separation layer 111. Furthermore, the first reflective layer 120 may have a planar shape according to the design of the display medium 100. In this embodiment, the first reflective layer 120 having a planar shape of the letter "B" is described as an example. In this example, the entire first reflective layer 120 overlaps a part of the polarization separation layer 111 and a part of the retardation layer 112 of the multilayer substrate 110 when viewed from the thickness direction.

[0051] The first reflective layer 120 has a circularly polarized light separation function. Therefore, the first reflective layer 120 has a circularly polarized light separation function in one rotation direction D B1 The circularly polarized light is reflected and rotated in the direction D. B1 It can transmit circularly polarized light having a rotation direction opposite to that of the first reflective layer 120. In the following description, the wavelength range in which the first reflective layer 120 can exhibit the circularly polarized light separation function is sometimes referred to as the "first reflection wavelength range" as appropriate. The range of the reflectance of the first reflective layer 120 for unpolarized light in the first reflection wavelength range can be the same as the range of the reflectance of the polarization separation layer 111 for unpolarized light in the polarization separation wavelength range.

[0052] The first reflection wavelength range of the first reflection layer 120 usually overlaps with the polarization separation wavelength range of the polarization separation layer 111 included in the multilayer substrate 110. A part of the first reflection wavelength range may overlap with a part of the polarization separation wavelength range, the whole of the first reflection wavelength range may overlap with a part of the polarization separation wavelength range, a part of the first reflection wavelength range may overlap with the whole of the polarization separation wavelength range, or the whole of the first reflection wavelength range may overlap with the whole of the polarization separation wavelength range. Among them, it is preferable that the whole of the first reflection wavelength range overlaps with a part or the whole of the polarization separation wavelength range, so that the first reflection wavelength range is within the polarization separation wavelength range. Therefore, preferably, the lower limit of the first reflection wavelength range is equal to or greater than the lower limit of the polarization separation wavelength range, and the upper limit of the first reflection wavelength range is equal to or less than the upper limit of the polarization separation wavelength range. In this case, when the display medium 100 is observed from the opposite side to the first reflection layer 120, the visibility of the first reflection layer 120 can be effectively reduced.

[0053] The rotation direction D of the circularly polarized light that the first reflective layer 120 can reflect B1 is the rotation direction D of the circularly polarized light that the polarization separation layer 111 can reflect. A Therefore, when light passes through the multilayer substrate 110 and enters the first reflective layer 120, the rotation direction D of at least a portion of the circularly polarized light (specifically, the circularly polarized light in the polarization separation wavelength range) contained in the light is set to be equal to the rotation direction D C and the rotation direction D of the circularly polarized light that the first reflective layer 120 can reflect. B1Therefore, the first reflective layer 120 may not reflect, or may only reflect very little, light that passes through the multi-layer substrate 110 and enters the first reflective layer 120.

[0054] Such a first reflective layer 120 may be a layer of cholesteric resin, but is preferably a layer containing flakes of cholesteric resin. The flakes of cholesteric resin can be used as a pigment containing a minute layer of cholesteric resin. Thus, the layer containing flakes of cholesteric resin can exhibit a circularly polarized light separation function, just like the layer of cholesteric resin itself. Usually, the shear force applied when forming a layer containing flakes of cholesteric resin causes the main surface of the flakes and the layer plane of the layer containing the flakes to be oriented parallel or nearly parallel. However, since there may be variations in the orientation direction of the flakes, the layer containing the cholesteric resin flakes as a whole may scatter the circularly polarized light reflected by the flakes. When this scattering occurs, the layer containing the cholesteric resin flakes may be visually recognized as an image different from the surroundings. Therefore, even if the polarization separation wavelength range of the polarization separation layer 111 and the first reflection wavelength range of the first reflective layer 120 match and the color of the polarization separation layer 111 and the color of the first reflective layer 120 are the same, the first reflective layer 120 can be seen due to the scattering described above.

[0055] The particle size of the cholesteric resin flakes is preferably 1 μm or more in terms of obtaining decorativeness. In particular, the particle size of the flakes is preferably equal to or greater than the thickness of the layer containing the flakes. In this case, it is easy to orient each flake so that the main surface of the flake is parallel to or forms an acute angle with the layer plane of the layer containing the flakes. Therefore, the flakes can receive light effectively, and the circularly polarized light separation function of the layer containing the flakes can be improved. From the viewpoint of obtaining moldability and printability, the upper limit of the particle size of the flakes is preferably 500 μm or less, more preferably 100 μm or less. Here, the particle size of the flakes refers to the diameter of a circle having the same area as the flakes.

[0056] As the flakes of the cholesteric resin, for example, crushed layers of the above-mentioned cholesteric resin can be used. Such flakes can be produced, for example, by the production method described in Japanese Patent No. 6142714.

[0057] The layer containing cholesteric resin flakes may contain any component in combination with the flakes. The optional component may be a binder that binds the flakes. Examples of the binder include polymers such as polyester polymers, acrylic polymers, polystyrene polymers, polyamide polymers, polyurethane polymers, polyolefin polymers, polycarbonate polymers, and polyvinyl polymers. The amount of the binder is preferably 20 parts by weight or more, more preferably 40 parts by weight or more, and particularly preferably 60 parts by weight or more, and is preferably 1000 parts by weight or less, more preferably 800 parts by weight or less, and particularly preferably 600 parts by weight or less, relative to 100 parts by weight of the flakes.

[0058] A layer containing flakes of a cholesteric resin can be produced, for example, by applying an ink containing flakes, a solvent, and, if necessary, any optional components, and drying the applied ink. As the solvent, an inorganic solvent such as water may be used, and an organic solvent such as a ketone solvent, an alkyl halide solvent, an amide solvent, a sulfoxide solvent, a heterocyclic compound, a hydrocarbon solvent, an ester solvent, and an ether solvent may be used. The amount of the solvent is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, and particularly preferably 80 parts by weight or more, and is preferably 1000 parts by weight or less, more preferably 800 parts by weight or less, and particularly preferably 600 parts by weight or less, relative to 100 parts by weight of the flakes.

[0059] The ink may contain a monomer of the polymer instead of or in combination with the polymer as a binder. In this case, the ink can be applied, dried, and then polymerized to form a layer containing flakes of the cholesteric resin. If a monomer is included, the ink preferably contains a polymerization initiator.

[0060] 4 and 5 are cross-sectional views showing a display medium 100 according to a first embodiment of the present invention. In these figures, the paths of light reflected at the polarization separation layer 111 and the first reflective layer 120 are shown. In the actual display medium 100, various light absorptions and reflections may occur in addition to those described below, but in the following description, for convenience of explaining the operation, the main light paths will be described in a simplified manner.

[0061] In FIG. 4, unpolarized light L, such as light including both right-handed and left-handed circularly polarized light, is incident on the first reflective layer 120 side of the display medium 100. I1 4, in the area where the first reflective layer 120 is not provided, the polarization separation layer 111 and the retardation layer 112 are arranged in this order, so that the irradiation light L I1 The irradiated light L I1 A part of the rotation direction D A Circularly polarized light R1 The reflected circularly polarized light L R1 Other than light L T1 The circularly polarized light L is transmitted through the polarization separation layer 111 and then through the retardation layer 112 to the outside of the display medium 100. R1 is reflected, so that immediately after passing through the polarization separation layer 111, the light L T1 A part or all of the rotation direction D A However, the rotation direction of the light L is reversed by passing through the retardation layer 112. T1 Some or all of the circularly polarized light contained in has a rotation direction D A It is circularly polarized in the same direction as the light.

[0062] In addition, as shown in FIG. 4, in the area where the first reflective layer 120 is provided, the first reflective layer 120, the polarization separation layer 111, and the retardation layer 112 are arranged in this order, so that the irradiated light L I1 The irradiation light L I1 A part of the circularly polarized light in the B1 Circularly polarized lightR2 The reflected circularly polarized light L R2 Other than light L T2 The light L enters the polarization separation layer 111. T2 The polarization separation layer 111 can reflect the light in the rotation direction D A Circularly polarized light R3 Therefore, the light L T2 A part of the rotation direction D A Circularly polarized light R3 The reflected circularly polarized light L R2 and L R3 Other than light L T3 The light L passes through the polarization separation layer 111, and then passes through the retardation layer 112 to exit the display medium 100. As in the area where the first reflective layer 120 is not provided, the light L passes through the retardation layer 112 and exits the display medium 100. T3 Some or all of the circularly polarized light contained in has a rotation direction D A It is circularly polarized in the same direction as the light.

[0063] In this way, the first reflective layer 120 side of the display medium 100 is exposed to irradiation light L I1 When the image is viewed with the circularly polarized light L1 reflected by the first reflective layer 120, the first reflective layer 120 reflects strong light. R2 Therefore, an observer viewing the display medium 100 from the first reflective layer 120 side can see an image of the first reflective layer 120, as shown in FIG.

[0064] On the other hand, in FIG. 5, unpolarized light L, which includes both right-handed and left-handed circularly polarized light, is irradiated on the side opposite to the first reflective layer 120 of the display medium 100. I2 As shown in FIG. 5, in the area where the first reflective layer 120 is not provided, the irradiated light L I2 After passing through the retardation layer 112 of the multilayer substrate 110, the irradiated light L enters the polarization separation layer 111. I2 A part of the rotation direction D A Circularly polarized light R4The reflected circularly polarized light L is reflected by the polarization separation layer 111 as a circularly polarized light L, and the rotation direction of the circularly polarized light L is inverted by transmitting through the phase difference layer 112. R4 Other than light L T4 The circularly polarized light L R4 is reflected, so that the light L that passes through the polarization separation layer 111 and exits from the display medium 100 T4 A part or all of the rotation direction D A The light is circularly polarized in the opposite direction.

[0065] 5, in the area where the first reflective layer 120 is provided, the irradiation light L I2 A part of the rotation direction D A Circularly polarized light R4 The reflected circularly polarized light L R4 Other than light L T4 The light L transmitted through the polarization separation layer 111 is T4 Then, the circularly polarized light L enters the first reflective layer 120. However, the circularly polarized light L R4 is reflected, so that the light L transmitted through the polarization separation layer 111 T4 The rotation direction of some or all of the circularly polarized light contained in the polarizing beam splitter 111 is R4 Rotation direction D A Here, the rotation direction D of the circularly polarized light that the first reflective layer 120 as the reflective layer according to this embodiment can reflect is B1 is the circularly polarized light L reflected by the polarization separation layer 111. R4 Rotation direction D A Therefore, the light L entering the first reflective layer 120 is the same as T4 is the rotation direction D in which the first reflective layer 120 can reflect. B1 Therefore, the light L T4 All or most of the light L is not reflected by the first reflective layer 120. T4 All or most of the light L T5The light having the rotation direction D of the circularly polarized light that can be reflected by the first reflective layer 120 passes through the first reflective layer 120 and exits the display medium 100. B1 and the direction of rotation of the circularly polarized light that the polarization separation layer 111 can reflect D A Since the light L T5 A part or all of the rotation direction D A The light is circularly polarized in the opposite direction.

[0066] In this way, the side opposite to the first reflective layer 120 of the display medium 100 is irradiated with the irradiation light L I2 When observed by illuminating with light, there is no light reflection or the reflection is weak at the first reflective layer 120, so the observer cannot see the light reflected by the first reflective layer 120. Therefore, an observer observing the display medium 100 from the opposite side to the first reflective layer 120 cannot see the image on the first reflective layer 120, as shown in FIG.

[0067] Therefore, in the display medium 100 according to this embodiment, the multilayer substrate 110 is transparent or semitransparent, but the first reflective layer 120 can be seen when observed from the first reflective layer side, but the first reflective layer 120 cannot be seen when observed from the opposite side to the first reflective layer 120. Thus, according to the display medium 100, although the multilayer substrate 110 is transparent or semitransparent, a unique display mode is possible in which the image of the display medium seen when observed from the front surface is different from the image of the display medium seen when observed from the back surface. Furthermore, when used as a display set (not shown in this embodiment) as described below, the image of the display medium 100 and the image of the display item (not shown in this embodiment) that are viewed can both be made different depending on the front and back orientation of the display medium 100.

[0068] [3. Second embodiment relating to display medium] In the first embodiment, an example is shown in which the first reflective layer 120 as a reflective layer is provided on the surface 110U of the multilayer base material 110 on the polarization separation layer side, but the reflective layer may be formed on the surface of the multilayer base material 110 on the retardation layer side. Hereinafter, an embodiment in which a second reflective layer as a reflective layer is provided on the surface of the multilayer base material 110 on the retardation layer side in this manner will be described.

[0069] Fig. 6 is a cross-sectional view showing a display medium 200 according to a second embodiment of the present invention. Fig. 7 is a schematic plan view showing the display medium 200 according to the second embodiment of the present invention as viewed from one side (the side opposite to the side on which the second reflective layer 220 is provided). Fig. 8 is a schematic plan view showing the display medium 200 according to the second embodiment of the present invention as viewed from the other side (the side on which the second reflective layer 220 is provided).

[0070] As shown in Figures 6 to 8, a display medium 200 according to a second embodiment of the present invention includes a multilayer substrate 110 having a polarization separation layer 111 and a retardation layer 112, and a second reflective layer 220 as a reflective layer provided on a surface 110D of the multilayer substrate 110 facing the retardation layer.

[0071] The multilayer substrate 110 of the display medium 200 according to the second embodiment may be the same as that of the display medium 100 according to the first embodiment. When the same multilayer substrate 110 as that described in the first embodiment is used in the display medium 200 according to the second embodiment, the same effect as that described in the first embodiment can be obtained.

[0072] The second reflective layer 220 as a reflective layer is provided on the surface 110D on the retardation layer side of the multilayer base material 110. The second reflective layer 220 may be provided directly or indirectly on the surface 110D of the multilayer base material 110, similar to the first reflective layer 120 described in the first embodiment.

[0073] The second reflective layer 220 may be provided on a part of the surface 110D of the multilayer substrate 110, or may be provided on the entire surface 110D. Usually, the second reflective layer 220 is provided so as to overlap both the polarization separation layer 111 and the retardation layer 112 of the multilayer substrate 110 as in the first embodiment, as viewed from the thickness direction. In this embodiment, the second reflective layer 220 having a planar shape of the letter "E" is described as an example. In this example, the entire second reflective layer 220 overlaps a part of the polarization separation layer 111 and a part of the retardation layer 112 of the multilayer substrate 110 as viewed from the thickness direction.

[0074] The second reflective layer 220 has a circularly polarized light separation function. Therefore, the second reflective layer 220 has a circularly polarized light separation function in one rotation direction D B2 The circularly polarized light is reflected and rotated in the direction D. B2 It is possible to transmit circularly polarized light having a rotation direction opposite to that of the first reflective layer 120. In the following description, such a wavelength range in which the second reflective layer 220 can exhibit the circularly polarized light separation function may be referred to as the "second reflection wavelength range" as appropriate. The range of the reflectance of the second reflective layer 220 to unpolarized light in the second reflection wavelength range may be the same as the range of the reflectance of the first reflective layer 120 to unpolarized light in the first reflection wavelength range described in the first embodiment.

[0075] The second reflection wavelength range of the second reflective layer 220 usually overlaps with the polarization separation wavelength range of the polarization separation layer 111 included in the multilayer substrate 110. A part of the second reflection wavelength range may overlap with a part of the polarization separation wavelength range, the whole of the second reflection wavelength range may overlap with a part of the polarization separation wavelength range, a part of the second reflection wavelength range may overlap with the whole of the polarization separation wavelength range, or the whole of the second reflection wavelength range may overlap with the whole of the polarization separation wavelength range. Among them, it is preferable that the whole of the second reflection wavelength range overlaps with a part or the whole of the polarization separation wavelength range, so that the second reflection wavelength range is within the polarization separation wavelength range. Therefore, preferably, the lower limit of the second reflection wavelength range is equal to or greater than the lower limit of the polarization separation wavelength range, and the upper limit of the second reflection wavelength range is equal to or less than the upper limit of the polarization separation wavelength range. In this case, when the display medium 200 is observed from the opposite side to the second reflection layer 220, the visibility of the second reflection layer 220 can be effectively reduced.

[0076] The rotation direction D of the circularly polarized light that the second reflective layer 220 can reflect B2 is the rotation direction D of the circularly polarized light that the polarization separation layer 111 can reflect. A Therefore, when light passes through the multilayer substrate 110 and enters the second reflective layer 220, the rotation direction D of at least a portion of the circularly polarized light (specifically, the circularly polarized light in the polarization separation wavelength range) contained in the light is opposite to that of the first reflective layer 220. C and the rotation direction D of the circularly polarized light that the second reflective layer 220 can reflect. B2 Therefore, the second reflective layer 220 may not reflect, or may only reflect very little, light that passes through the multi-layer substrate 110 and enters the second reflective layer 220.

[0077] The second reflective layer 220 may be a layer of cholesteric resin like the first reflective layer 120 described in the first embodiment, but is preferably a layer containing flakes of cholesteric resin. When a layer containing flakes of cholesteric resin is used as the second reflective layer 220, the same effects as those described in the first embodiment can be obtained.

[0078] 9 and 10 are cross-sectional views showing a display medium 200 according to a second embodiment of the present invention. In these figures, the paths of light reflected at the polarization separation layer 111 and the second reflective layer 220 are shown. In the actual display medium 200, various light absorptions and reflections may occur in addition to those described below, but in the following description, for convenience of explanation of the operation, the main light paths will be described in a simplified manner.

[0079] In FIG. 9, unpolarized light L, such as light including both right-handed and left-handed circularly polarized light, is incident on the side of the display medium 200 opposite the second reflective layer 220. I3 9, in the area where the second reflective layer 220 is not provided, the polarization separation layer 111 and the retardation layer 112 are arranged in this order, so that the irradiation light L I3 The irradiated light L I3 A part of the rotation direction D A Circularly polarized light R5 The reflected circularly polarized light L R5 Other than light L T6 The circularly polarized light L is transmitted through the polarization separation layer 111 and then through the retardation layer 112 to the outside of the display medium 200. R5 is reflected, so that immediately after passing through the polarization separation layer 111, the light L T6 A part or all of the rotation direction D A However, the rotation direction of the light L is reversed by passing through the retardation layer 112. T6 Some or all of the circularly polarized light contained in has a rotation direction D A It is circularly polarized in the same direction as the light.

[0080] 9, in the area where the second reflective layer 220 is provided, the polarization separation layer 111, the retardation layer 112, and the second reflective layer 220 are arranged in this order, so that the irradiation light L I3 A part of the rotation direction D A Circularly polarized light R5The reflected circularly polarized light L R5 Other than light L T6 The light L transmitted through the polarization separation layer 111 and the retardation layer 112. T6 Then, the light L enters the second reflective layer 220. However, after passing through the retardation layer 112, T6 The rotation direction of some or all of the circularly polarized light contained in the polarizing beam splitter 111 is R5 Rotation direction D A Here, the rotation direction D of the circularly polarized light that can be reflected by the second reflective layer 220 as the reflective layer according to this embodiment is the same as B2 is the circularly polarized light L reflected by the polarization separation layer 111. R5 Rotation direction D A Therefore, the light L entering the second reflective layer 220 T6 is the rotation direction D in which the second reflective layer 220 can reflect. B2 It contains no or only a small amount of circularly polarized light. T6 All or most of the circularly polarized light is not reflected by the second reflective layer 220. B2 and the direction of rotation of the circularly polarized light that the polarization separation layer 111 can reflect D A Therefore, in the area where the second reflective layer 220 is provided, the light L 1 that passes through the second reflective layer 220 and exits from the display medium 200 is the same as in the area where the second reflective layer 220 is not provided. T7 A part or all of the rotation direction D A It is circularly polarized in the same direction as the light.

[0081] In this way, the side opposite to the second reflective layer 220 of the display medium 200 is irradiated with the irradiation light L I3 When observed by illuminating with light, there is no light reflection or the reflection is weak at the second reflective layer 220, so the observer cannot see the light reflected by the second reflective layer 220. Therefore, an observer observing the display medium 200 from the opposite side to the second reflective layer 220 cannot see the image on the second reflective layer 220, as shown in FIG.

[0082] On the other hand, in FIG. 10, unpolarized light L, such as light including both right-handed and left-handed circularly polarized light, is applied to the second reflective layer 220 side of the display medium 200. I4 As shown in FIG. 10, in the area where the second reflective layer 220 is not provided, the irradiation light L I4 After passing through the retardation layer 112 of the multilayer substrate 110, the irradiated light L enters the polarization separation layer 111. I4 A part of the rotation direction D A Circularly polarized light R6 The reflected circularly polarized light L is reflected by the polarization separation layer 111 as a circularly polarized light L, and the rotation direction of the circularly polarized light L is inverted by transmitting through the phase difference layer 112. R6 Other than light L T8 The circularly polarized light L R6 is reflected, so that the light L that passes through the polarization separation layer 111 and exits from the display medium 200 T8 A part or all of the rotation direction D A The light is circularly polarized in the opposite direction.

[0083] In addition, as shown in FIG. 10, in the area where the second reflective layer 220 is provided, the irradiated light L I4 The irradiation light L I4 A part of the circularly polarized light in the B2 Circularly polarized light R7 The reflected circularly polarized light L R7 Other than light L T9 The light L is transmitted through the retardation layer 112 and enters the polarization separation layer 111. T9 The polarization separation layer 111 can reflect the light in the rotation direction D A Circularly polarized light R8 Therefore, the light L T9 A part of the rotation direction D A Circularly polarized light R8 The reflected circularly polarized light L R7 and L R8 Other than light L T10The light L passes through the polarization separation layer 111 and exits the display medium 200. As in the area where the second reflective layer 220 is not provided, the light L passes through the polarization separation layer 111 and exits the display medium 200. T10 Therefore, the light L that passes through the polarization separation layer 111 and exits from the display medium 200 T10 A part or all of the rotation direction D A The light is circularly polarized in the opposite direction.

[0084] In this way, the second reflective layer 220 side of the display medium 200 is illuminated with irradiation light L I4 When the image is observed by illuminating the screen with the circularly polarized light L1, strong light reflection occurs at the second reflective layer 220, and the observer perceives the circularly polarized light L1 reflected at the second reflective layer 220. R7 Therefore, an observer observing the display medium 200 from the second reflective layer 220 side can visually recognize an image of the second reflective layer 220, as shown in FIG.

[0085] Therefore, in the display medium 200 according to this embodiment, the multilayer substrate 110 is transparent or semi-transparent, and the second reflective layer 220 can be seen when observed from the second reflective layer 220 side, but the second reflective layer 220 cannot be seen when observed from the opposite side to the second reflective layer 220. Therefore, according to the display medium 200, a unique display mode is possible in which the image of the display medium seen when observed from the front surface is different from the image of the display medium seen when observed from the back surface, even though the multilayer substrate 110 is transparent or semi-transparent. In addition, according to the display medium 200 according to this embodiment, the same advantages as the display medium 100 described in the first embodiment can be obtained.

[0086] [4. Third embodiment relating to display medium] In the first and second embodiments, the first reflective layer 120 or the second reflective layer 220 is provided as a reflective layer on one surface 110U or 110D of the multilayer substrate 110, but the display medium may have a reflective layer on both surfaces thereof. Hereinafter, an embodiment in which the first reflective layer and the second reflective layer are provided as reflective layers on both surfaces of the multilayer substrate 110 in this manner will be described.

[0087] Fig. 11 is a cross-sectional view showing a display medium 300 according to a third embodiment of the present invention. Fig. 12 is a schematic plan view showing the display medium 300 according to the third embodiment of the present invention as viewed from one side (the side on which the first reflective layer 120 is provided). Fig. 13 is a schematic plan view showing the display medium 300 according to the third embodiment of the present invention as viewed from the other side (the side on which the second reflective layer 220 is provided).

[0088] As shown in Figures 11 to 13, a display medium 300 according to a third embodiment of the present invention includes a multilayer substrate 110 having a polarization separation layer 111 and a retardation layer 112, a first reflective layer 120 as a reflective layer provided on a surface 110U of the multilayer substrate 110 facing the polarization separation layer, and a second reflective layer 220 as a reflective layer provided on a surface 110D of the multilayer substrate 110 facing the retardation layer.

[0089] The multilayer substrate 110 of the display medium 300 according to the third embodiment may be the same as that of the display medium 100 according to the first embodiment. When the same multilayer substrate 110 as that described in the first embodiment is used in the display medium 300 according to the third embodiment, the same effect as that described in the first embodiment can be obtained.

[0090] The first reflective layer 120 of the display medium 300 according to the third embodiment may be the same as that of the display medium 100 according to the first embodiment. When the same first reflective layer 120 as that described in the first embodiment is used in the display medium 300 according to the third embodiment, the same effect as that described in the first embodiment can be obtained.

[0091] The second reflective layer 220 of the display medium 300 according to the third embodiment may be the same as that of the display medium 200 according to the second embodiment. When the same second reflective layer 220 as that described in the second embodiment is used in the display medium 300 according to the third embodiment, the same effect as that described in the second embodiment can be obtained.

[0092] The first reflective layer 120 of the display medium 300 can be viewed by an observer observing the display medium 300 from the first reflective layer 120 side under irradiation light including both right-handed and left-handed circularly polarized light (FIG. 12) by the same mechanism as described in the first embodiment, but cannot be viewed by an observer observing the display medium 300 from the second reflective layer 220 side, which is the opposite side to the first reflective layer 120 (FIG. 13). On the other hand, the second reflective layer 220 of the display medium 300 can be viewed by an observer observing the display medium 300 from the second reflective layer 220 side under irradiation light including both right-handed and left-handed circularly polarized light by the same mechanism as described in the second embodiment (FIG. 13), but cannot be viewed by an observer observing the display medium 300 from the first reflective layer 120 side, which is the opposite side to the second reflective layer 220 (FIG. 12). Therefore, the display medium 300 according to this embodiment allows a unique display mode in which the image of the display medium observed from the front side is different from the image of the display medium observed from the back side, even though the multilayer substrate 110 is transparent or semi-transparent. Also, the display medium 300 according to this embodiment can provide the same advantages as the display media 100 and 200 described in the first and second embodiments.

[0093] When multiple reflective layers 120 and 220 are provided on the display medium 300 as in this embodiment, the shapes, dimensions, and materials of the reflective layers, as well as the wavelength and reflectance of the circularly polarized light reflected by the reflective layers, may be the same or different.

[0094] [5. Modifications related to display media] The display medium is not limited to those described in the first to third embodiments. For example, the display medium may further include any element in combination with the multilayer substrate 110, the first reflective layer 120, the second reflective layer 220, and other reflective layers.

[0095] For example, the display medium may have any layer having a circularly polarized light separation function on the surfaces 110U and 110D of the multilayer substrate 110 in addition to the first reflective layer 120 and the second reflective layer 220. As a specific example, a circularly polarized light rotation direction D that the polarization separation layer 111 can reflect may be provided on the surface 110U of the multilayer substrate 110 on the polarization separation layer side. A and the opposite rotation direction D E1 The circularly polarized light is reflected and rotated in the direction D. E1 In another specific example, the multilayer substrate 110 may have a first arbitrary layer that can transmit circularly polarized light having a rotation direction opposite to that of the polarization separation layer 111. A Same rotation direction as D E2 The circularly polarized light is reflected and rotated in the direction D. E2 The polarizing plate may further include a second optional layer capable of transmitting circularly polarized light having a rotation direction opposite to that of the first optional layer. These optional layers may be formed, for example, as a layer of a cholesteric resin, a layer containing flakes of a cholesteric resin, etc. These optional layers are usually visible when observed from both the front surface and the back surface.

[0096] Also, for example, the display medium may have any non-chiral layer containing a colorant such as a pigment or dye that does not have a circularly polarized light separation function. This non-chiral layer may be provided on the surface 110U of the multilayer substrate 110 on the polarization separation layer side, or on the surface 110D on the retardation layer side. This non-chiral layer can usually be viewed both when observed from the front surface and when observed from the back surface.

[0097] Furthermore, for example, the display medium may have an adhesive layer for bonding the above-mentioned layers together. As a specific example, the display medium may have an adhesive layer between the multilayer substrate 110 and the first reflective layer 120, and may have an adhesive layer between the multilayer substrate 110 and the second reflective layer 220. This adhesive layer preferably has a small in-plane retardation, like any layer that the multilayer substrate 110 may have.

[0098] For example, the display medium may also include a cover layer that protects each of the above-mentioned layers. These cover layers are preferably provided on the outside of the above-mentioned layers. As a specific example, the display medium may include a cover layer, a second reflective layer, a multilayer substrate, a first reflective layer, and a cover layer in this order in the thickness direction. Such a cover layer may be formed of a transparent material, for example, a resin.

[0099] Furthermore, for example, the display medium may have any layer with small in-plane retardation between the above-mentioned layers and as the outermost layer of the display medium, as long as the effect of the present invention is not significantly impaired. Such any layer with small in-plane retardation may be referred to as a "low Re layer" hereinafter. The specific in-plane retardation of this low Re layer is usually 0 nm or more and 5 nm or less. The position where the low Re layer is provided may include, for example, the position on the opposite side of the first reflective layer to the multilayer substrate, the position between the first reflective layer and the multilayer substrate, the position between the polarization separation layer and the retardation layer, the position between the multilayer substrate and the second reflective layer, the position on the opposite side of the second reflective layer to the multilayer substrate, and the like, but is not limited thereto. The low Re layer preferably has high light transmittance, and the total light transmittance of the low Re layer is preferably 80% or more, more preferably 85% or more. Examples of materials for such low Re layers include rigid polyvinyl chloride, flexible polyvinyl chloride, acrylic resin, glass, polycarbonate (PC), and polyethylene terephthalate (PET). The specific material can be appropriately selected depending on the application of the display medium and the desired texture, durability, and mechanical strength.

[0100] [6. Fourth embodiment relating to display set] The above-mentioned display medium can be used as a display set in combination with a display article to be viewed through the display medium. The display article to be combined with the display medium includes a base article and a display layer provided on the base article. The display layer is a layer having a circularly polarized light separation function, and has a circularly polarized light separation function in one rotation direction D. D The circularly polarized light is reflected and rotated in the direction D. D Therefore, the direction of rotation of the circularly polarized light reflected from the display layer is DD A part or all of the circularly polarized light can be transmitted through the multilayer substrate of the display medium in one of the following orders (i) and (ii), but cannot be transmitted in the other order. (i) The order of the polarization separation layer and the retardation layer. (ii) The order of the retardation layer and the polarization separation layer.

[0101] Therefore, according to the display set, the image of the display article viewed through the display medium can be made different depending on the front and back orientation of the display medium. Also, as described above, the image of the display medium itself can be made different depending on the front and back orientation of the display medium. Hereinafter, an embodiment of this display set will be described in detail with reference to the drawings.

[0102] Fig. 14 is a cross-sectional view that illustrates a display set 400 according to a fourth embodiment of the present invention. As illustrated in Fig. 14, the display set 400 according to the fourth embodiment of the present invention includes a display medium 300 and a display article 500. In this embodiment, the display set 400 including the display medium 300 described in the third embodiment will be described as an example.

[0103] Fig. 15 is a cross-sectional view that shows a display article 500 included in a display set 400 according to a fourth embodiment of the present invention. Fig. 16 is a plan view that shows a display article 500 included in a display set 400 according to a fourth embodiment of the present invention. As shown in Figs. 15 and 16, the display article 500 includes a base article 510, and a first display layer 520 and a second display layer 530 that serve as display layers provided on the base article 510.

[0104] The base article 510 is an article on which display layers such as the first display layer 520 and the second display layer 530 are provided, and there is no limitation on the scope of the base article 510. Examples of the base article 510 include, but are not limited to, cloth products such as clothing, leather products such as bags and shoes, metal products such as screws, paper products such as price tags, plastic products such as cards and plastic bills, and rubber products such as tires.

[0105] The first display layer 520 and the second display layer 530 as display layers each have a circularly polarized light separation function. In this embodiment, the first display layer 520 can reflect the circularly polarized light in the rotation direction D D1 and the rotation direction D of the circularly polarized light that the second display layer 530 can reflect. D2 Specifically, the first display layer 520 has a rotation direction D of the circularly polarized light that can be reflected by the polarization separation layer 111 of the display medium 300 in the wavelength range in which the circularly polarized light separation function can be exerted. A Same rotation direction as D D1 The circularly polarized light is reflected and rotated in the direction D. D1 On the other hand, the second display layer 530 can transmit circularly polarized light having a rotation direction opposite to that of the polarization separation layer 111 in the wavelength range in which the circularly polarized light separation function can be exerted. A and the opposite rotation direction D D2 The circularly polarized light is reflected and rotated in the direction D. D2 It can transmit circularly polarized light having the opposite rotation direction to that of the polarizer.

[0106] In the following description, the wavelength range in which the first display layer 520 can exhibit the circular polarization separation function may be referred to as the "first display wavelength range" as appropriate. Also, the wavelength range in which the second display layer 530 can exhibit the circular polarization separation function may be referred to as the "second display wavelength range" as appropriate. Furthermore, the first display wavelength range and the second display wavelength range may be collectively referred to simply as the "display wavelength range". The range of the reflectance of the first display layer 520 and the second display layer 530 for unpolarized light in the display wavelength range may be the same as the range of the reflectance of the polarization separation layer 111 for unpolarized light in the polarization separation wavelength range. In this case, the reflectance of the first display layer 520 and the reflectance of the second display layer 530 may be the same or different.

[0107] The display wavelength ranges of the first display layer 520 and the second display layer 530 usually overlap with the polarization separation wavelength range of the polarization separation layer 111 of the display medium 300. A part of the display wavelength range may overlap with a part of the polarization separation wavelength range, the whole of the display wavelength range may overlap with a part of the polarization separation wavelength range, a part of the display wavelength range may overlap with the whole of the polarization separation wavelength range, or the whole of the display wavelength range may overlap with the whole of the polarization separation wavelength range. Among them, it is preferable that the whole of the display wavelength range overlaps with a part or the whole of the polarization separation wavelength range, so that the display wavelength range is within the polarization separation wavelength range. Therefore, preferably, the lower limit of the display wavelength range is equal to or greater than the lower limit of the polarization separation wavelength range, and the upper limit of the display wavelength range is equal to or less than the upper limit of the polarization separation wavelength range. In this case, when the front and back orientations of the display medium 300 are appropriate, the multilayer substrate 110 can effectively block the circularly polarized light reflected by the first display layer 520 or the second display layer 530.

[0108] The first display layer 520 and the second display layer 530 may be layers of cholesteric resin, similar to the first reflective layer 120 described in the first embodiment, but are preferably layers containing flakes of cholesteric resin.

[0109] In this embodiment, a display article 500 is shown as an example in which a first display layer 520 having a planar shape of the letter "I" and a second display layer 530 having a planar shape of the letter "S" are provided on a sheet-like base article 510.

[0110] Furthermore, the display article 500 may include an optional non-chiral layer 540 containing a colorant such as a pigment or dye that does not have a circularly polarized light separation function, as necessary. In this embodiment, a non-chiral layer 540 having a planar shape of the letter "M" will be described as an example.

[0111] The display set 400 includes a combination of the display medium 300 having the above-described configuration and the display article 500. Thus, the viewer can view the image described below.

[0112] 14, a case will be described in which the display medium 300 and the display article 500 are stacked in such a manner that the surface 110D of the multilayer base material 110 on the side of the retardation layer 112 faces the display article 500. In this case, the viewer usually views the display set 400 from above in the figure. Therefore, the viewer views the display medium 300 from the first reflective layer 120 side and the display article 500 through the display medium 300 at the same time.

[0113] Fig. 17 is a plan view showing a schematic image seen when the display set 400 shown in Fig. 14 is observed from above in the figure. As shown in Fig. 17, in the image seen by the observer who observed the display set 400 as described above, the first reflective layer 120 of the display medium 300 and the first display layer 520 and the non-chiral layer 540 of the display article 500 appear, but the second reflective layer 220 of the display medium 300 and the second display layer 530 of the display article 500 do not appear. The mechanism by which such an image is seen is as follows.

[0114] 14, the polarization separation layer 111, the retardation layer 112, and the display article 500 are arranged in this order in the thickness direction of the display medium 300. Thus, of the light irradiated to the display medium 300, a part of the circularly polarized light is reflected by the polarization separation layer 111, and the light other than the reflected circularly polarized light passes through the retardation layer 112 and then enters the display article 500. In this way, a part or all of the light entering the display article 500 is rotated in the direction D of the circularly polarized light reflected by the polarization separation layer 111. A The light is circularly polarized in the same direction as the light in Figure 4. T1 and L T3 , and the light L in FIG. T6 and L T7 (see ).

[0115] Therefore, the direction of rotation is D A Same rotation direction as D D1 In the first display layer 520 capable of reflecting circularly polarized light, the light passing through the display medium 300 and entering the display article 500 is largely reflected. The reflected light is then reflected in the direction of rotation D. D1Since the light is circularly polarized, its rotation direction is reversed by passing through the retardation layer 112, and the light can be transmitted through the polarization separation layer 111. Therefore, the strong light reflected by the first display layer 520 can be transmitted through the display medium 300, and the viewer can visually recognize the image on the first display layer 520.

[0116] Also, the rotation direction D A and the opposite rotation direction D D2 In the second display layer 530 capable of reflecting circularly polarized light, the light passing through the display medium 300 and entering the display article 500 is not reflected or is only weakly reflected. Even if the second display layer 530 reflects light, the reflected light is reflected in the rotation direction D. D2 Since the light is circularly polarized light, its direction of rotation is reversed by passing through the retardation layer 112, and a part or all of the light is reflected by the polarization separation layer 111. Therefore, the light that can be reflected by the second display layer 530 and transmitted through the display medium 300 is absent or weak, and therefore the viewer cannot see the image on the second display layer 530.

[0117] Furthermore, in the non-chiral layer 540, reflection of light occurs regardless of the polarization state of the light entering the display article 500. Therefore, a part or all of the reflected light can be transmitted through the display medium 300, and an observer can see an image of the non-chiral layer 540.

[0118] Furthermore, as described in the first to third embodiments, the observer can see the image of the first reflective layer 120 observed without passing through the multilayer substrate 110, but cannot see the image of the second reflective layer 220 observed through the multilayer substrate 110.

[0119] Thus, as shown in FIG. 17, an observer can see the image represented by the first reflective layer 120 (the letter "B"), the image represented by the first display layer 520 (the letter "I"), and the layer represented by the non-chiral layer 540 (the letter "M"), but cannot see the image represented by the second reflective layer 220 or the image represented by the second display layer 530.

[0120] Next, a case where the display medium 300 is turned over will be described. FIG. 18 is a cross-sectional view that shows a display set 400 according to a fourth embodiment of the present invention. In this case, as shown in FIG. 18, the display medium 300 and the display article 500 are stacked with the surface 110U of the multilayer base material 110 on the polarization separation layer 111 side facing the display article 500. In this case, the viewer usually views the display set 400 from above in the figure. Therefore, the viewer views the display medium 300 from the second reflective layer 220 side and the display article 500 through the display medium 300 at the same time.

[0121] Fig. 19 is a plan view showing a schematic image visually recognized when the display set 400 shown in Fig. 18 is observed from above in the figure. As shown in Fig. 19, in the image visually recognized by the observer who observed the display set 400 as described above, the second reflective layer 220 of the display medium 300 and the second display layer 530 and the non-chiral layer 540 of the display article 500 appear, but the first reflective layer 120 of the display medium 300 and the first display layer 520 of the display article 500 do not appear. The mechanism by which such an image is visually recognized is as follows.

[0122] 18, the retardation layer 112, the polarization separation layer 111, and the display article 500 are arranged in this order in the thickness direction of the display medium 300. Thus, the light irradiated to the display medium 300 passes through the retardation layer 112, and enters the display article 500 after a portion of the circularly polarized light is reflected by the polarization separation layer 111. In this way, a portion or all of the light entering the display article 500 is reflected in the direction of rotation D of the circularly polarized light reflected by the polarization separation layer 111. A The light is circularly polarized in the opposite direction to the direction of rotation of the light L in Figure 5. T4 and L T5 , and the light L in FIG. T8 and L T10 (see ).

[0123] Therefore, the direction of rotation is D A Same rotation direction as D D1In the first display layer 520 capable of reflecting circularly polarized light, the light passing through the display medium 300 and entering the display article 500 is not reflected or is only weakly reflected. Even if the first display layer 520 reflects light, the reflected light is reflected in the rotation direction D. D1 Since the light is circularly polarized, it is partially or entirely reflected by the polarization separation layer 111. Therefore, the light that can be reflected by the first display layer 520 and transmitted through the display medium 300 is absent or weak, and the viewer cannot see the image on the first display layer 520.

[0124] Also, the rotation direction D A and the opposite rotation direction D D2 In the second display layer 530 capable of reflecting circularly polarized light, the light passing through the display medium 300 and entering the display article 500 is largely reflected. The reflected light is then reflected in the direction of rotation D. D2 Since the light is circularly polarized, it can be transmitted through the polarization separation layer 111. Therefore, the strong light reflected by the second display layer 530 can be transmitted through the display medium 300, and the viewer can visually recognize the image on the second display layer 530.

[0125] Furthermore, in the non-chiral layer 540, reflection of light occurs regardless of the polarization state of the light entering the display article 500. Therefore, a part or all of the reflected light can be transmitted through the display medium 300, and an observer can see an image of the non-chiral layer 540.

[0126] Furthermore, as described in the first to third embodiments, the observer can see the image of the second reflective layer 220 observed without passing through the multilayer substrate 110, but cannot see the image of the first reflective layer 120 observed through the multilayer substrate 110.

[0127] Thus, as shown in FIG. 19, an observer can see the image represented by the second reflective layer 220 (the letter "E"), the image represented by the second display layer 530 (the letter "S"), and the layer represented by the non-chiral layer 540 (the letter "M"), but cannot see the image represented by the first reflective layer 120 or the image represented by the first display layer 520.

[0128] As described above, in the display set according to this embodiment, the image to be viewed can be made different depending on the orientation of the display medium 300. Therefore, by combining different images in this way, a new display mode that has not existed in the past can be realized, and a complex and highly flexible design can be created. In particular, in an environment under irradiation light that includes both right-handed and left-handed circularly polarized light, even if the multilayer base material 110 of the display medium 300 is transparent or translucent, the difference in the image as described above depending on the orientation of the display medium 300 can be a surprising display to a general observer, and it is expected to have a great impact on the observer.

[0129] In the fourth embodiment, the display article 500 including both the first display layer 520 and the second display layer 530 has been described as an example, but a display article including at least one of the first display layer 520 and the second display layer 530 may be used. For example, a display article including one or more first display layers 520 and no second display layer 530 may be used. Also, for example, a display article including one or more second display layers 530 and no first display layer 520 may be used. EXAMPLES

[0130] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and carried out as desired without departing from the scope of the claims of the present invention and the scope of equivalents thereto. In the following description, the units "%" and "parts" that represent amounts are by weight unless otherwise specified. Furthermore, the following operations were carried out in air at room temperature and normal pressure unless otherwise specified. In the following description, unless otherwise specified, the adhesive used was a transparent adhesive tape "LUCIACS CS9621T" (thickness 25 μm, visible light transmittance 90% or more, in-plane retardation 3 nm or less) manufactured by Nitto Denko Corporation.

[0131] [Method for measuring reflectance of cholesteric resin layer] The substrate film was peeled off from the multilayer film to obtain a cholesteric resin layer. The reflectance of this cholesteric resin layer when non-polarized light (wavelength 400 nm to 800 nm) was incident on the layer was measured using an ultraviolet-visible spectrophotometer ("UV-Vis 550" manufactured by JASCO Corporation).

[0132] [Method of measuring in-plane retardation] The in-plane retardation was measured at a measurement wavelength of 590 nm using a phase difference meter (Axoscan, manufactured by Axometrics).

[0133] [Production Example 1: Production of a cholesteric resin layer capable of reflecting right-handed circularly polarized light] A liquid crystal composition was prepared by mixing 100 parts of a photopolymerizable liquid crystal compound represented by the following formula (X1), 25 parts of a photopolymerizable non-liquid crystal compound represented by the following formula (X2), 8 parts of a chiral agent ("LC756" manufactured by BASF), 5 parts of a photopolymerization initiator ("Irgacure 907" manufactured by Ciba Japan), 0.15 parts of a surfactant ("S-420" manufactured by AGC Seimi Chemical Co., Ltd.), and 320 parts of cyclopentanone as a solvent.

[0134] [ka]

[0135] [ka]

[0136] A long polyethylene terephthalate film ("A4100" manufactured by Toyobo Co., Ltd.; thickness 100 μm) was prepared as the base film. This base film was attached to the unwinding section of a film transport device, and the following operations were performed while transporting the base film in the long direction.

[0137] The surface of the substrate film was subjected to a rubbing treatment in the longitudinal direction parallel to the transport direction. Next, a liquid crystal composition was applied to the rubbed surface of the substrate film using a die coater to form a layer of the liquid crystal composition. This layer of the liquid crystal composition was subjected to an alignment treatment by heating at 120°C for 4 minutes. Thereafter, the layer of the liquid crystal composition was subjected to a band broadening treatment. In this band broadening treatment, 5 mJ / cm 2 ~30mJ / cm 2 The reflection band was controlled to the desired bandwidth by repeatedly alternating between weak ultraviolet irradiation at 800 mJ / cm and heating at 100 to 120 °C. 2 The liquid crystal composition layer was irradiated with ultraviolet light of 100 nm to cure the liquid crystal composition layer. This resulted in a multilayer film including a substrate film and a cholesteric resin layer. The reflectance of the cholesteric resin layer of this multilayer film was measured by the above-mentioned measurement method. As a result of the measurement, the cholesteric resin layer had a reflectance of 40% or more for unpolarized light in the wavelength range from 450 nm to 700 nm.

[0138] [Production Example 2: Production of ink containing flakes of cholesteric resin capable of reflecting right-handed circularly polarized light] The cholesteric resin layer was peeled off from the multilayer film produced in Production Example 1. The peeled off cholesteric resin layer was pulverized to obtain flakes. 10 parts of the flakes were mixed with 85 parts of screen ink ("No. 2500 Medium" manufactured by Jujo Chemical Co., Ltd.) and 5 parts of a dedicated diluent for the screen ink (Tetoron standard solvent) to obtain an ink.

[0139] [Production Example 3: Production of ink containing flakes of cholesteric resin capable of reflecting left-handed circularly polarized light] Except for changing the type of chiral agent to 20 parts of D-mannitol, 1,4:3,6-dihydro-, 2,5-bis[4-[[[6-[[[4-[(1-oxo-2-propen-1-yl)oxy]butoxy]carbonyl]oxy]-2-naphthalenyl]carbonyl]oxy]benzoate] shown in the following formula (X3), the same operation as in Production Example 1 was performed to obtain a multilayer film having a base film and a cholesteric resin layer. The reflectance of the cholesteric resin layer of this multilayer film was measured by the above-mentioned measurement method. As a result of the measurement, the cholesteric resin layer had a wavelength range of 450 nm to 700 nm in which the reflectance to unpolarized light was 40% or more.

[0140] [ka]

[0141] The cholesteric resin layer was peeled off from the multilayer film thus obtained and pulverized to obtain flakes. 10 parts of the flakes were mixed with 85 parts of screen ink ("No. 2500 Medium" manufactured by Jujo Chemical Co., Ltd.) and 5 parts of a diluent (Tetoron standard solvent) for the screen ink to obtain an ink.

[0142] [Production Example 4: Production of Retardation Film] A substrate film containing a norbornene-based polymer as a cyclic structure-containing polymer ("ZEONOR film" manufactured by Zeon Corporation; a film manufactured by extrusion molding, unstretched product) was prepared. This substrate film was stretched in one direction by 3.9 times at a stretching temperature of 130°C to obtain a retardation film. The thickness of this retardation film was 38 μm, and the in-plane retardation was 280 nm.

[0143] [Example 1] (Display set overview) Fig. 20 is a cross-sectional view that shows a schematic diagram of the display set 1 produced in Example 1. As shown in Fig. 20, the display set 1 produced in Example 1 includes a display medium 10 and a display article 20. The display medium 10 includes a multilayer substrate 13 having a polarization separation layer 11 and a retardation layer 12; a character layer B as a first reflective layer provided on the surface of the multilayer substrate 13 facing the polarization separation layer; R and a character layer E as a second reflective layer provided on the retardation layer side of the multilayer substrate 13. L The display medium 10 manufactured in Example 1 includes a support layer and an adhesive, but these are not shown in FIG. 20. The display article 20 includes a base article 21 and a character layer I as a first display layer provided on the base article 21. R , the character layer S as the second display layer L and a character layer Mx as a non-chiral layer. A method for producing this display set 1 will be described below.

[0144] (Display media manufacturing) The cholesteric resin layer of the multilayer film produced in Production Example 1 was bonded to an optically isotropic support film (a polyvinyl chloride film) via an adhesive, and the base film of the multilayer film was peeled off. The surface of the cholesteric resin layer revealed by peeling off the base film was bonded to the retardation film produced in Production Example 4 via an adhesive. As a result, as shown in FIG. 20, a multilayer base material 13 was obtained that includes, in this order, a support layer (not shown) as a support film, an adhesive (not shown), a polarization separation layer 11 as a cholesteric resin layer, an adhesive (not shown), and a retardation layer 12 as a retardation film.

[0145] The letter "B" was printed on the surface of the multilayer substrate 13 facing the polarization separation layer using the ink produced in Production Example 2, and then dried to form a letter layer B as a first reflective layer. R In addition, the letter "E" was printed on the retardation layer side of the multilayer substrate 13 using the ink produced in Production Example 3, and then dried to form a letter layer E as a second reflective layer. L This resulted in the formation of character layer B. R , the polarization separation layer 11, the retardation layer 12, and the character layer E LA display medium 10 having the above in this order in the thickness direction was obtained.

[0146] (Manufacture of display items) The letter "I" was printed on one side of a black resin sheet using the ink produced in Production Example 2, and then dried to form a letter layer I as a first display layer. R In addition, the letter "S" was printed on one side of the black sheet using the ink produced in Production Example 3, and then dried to form a letter layer S as a second display layer. L Furthermore, the letter "M" was printed on one side of the black sheet with a commercially available silver ink and dried to form a letter layer M as a non-chiral layer. X As a result, a character layer I was formed on one side of the base article 21 as a black sheet. R , character layer S L and character layer M X Thus, a display article 20 having the above structure was obtained.

[0147] (observation) As shown in Figure 20, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. R The display medium 10 was placed with the side facing up. The display set 1 consisting of the display medium 10 and the display article 20 was observed from above under non-polarized illumination. R , character layer B R and character layer M X was visible, but the character layer S L and character layer E L was not visible.

[0148] Thereafter, the display medium 10 was turned over and placed on the display article 20, and the display set 1 was observed again. L , Character Layer E L and character layer M X was visible, but the character layer I R and character layer B R was not visible.

[0149] The results of Example 1 are summarized in Table 1 below. In the column "Direction of reflective circularly polarized light" in Table 1, the meanings of the abbreviations "positive", "negative" and "negative" are as follows. "Positive": The rotation direction of the circularly polarized light that the character layer can reflect is the same as the rotation direction of the circularly polarized light that the polarizing separation layer can reflect. "Reverse": The rotation direction of the circularly polarized light that the character layer can reflect is opposite to the rotation direction of the circularly polarized light that the polarizing separation layer can reflect. "Non": The character layer does not have a circularly polarized light separating function.

[0150] [Table 1]

[0151] [Example 2] (Display set description) FIG. 21 is a cross-sectional view that shows a schematic diagram of the display set 2 produced in Example 2. As shown in FIG. 21, the display set 2 produced in Example 2 includes a display medium 30 and a display article 20. The display article 20 is the same as that in Example 1. The display medium 30 includes a character layer E L Instead of the letter E R 1. Except for the formation of the display medium 10, this embodiment is the same as the display medium 10 of the first embodiment.

[0152] Character Layer E R The same procedure was repeated for the character layer E formed in Example 1, except that the ink produced in Production Example 2 was used instead of the ink produced in Production Example 3. L This character layer E was formed in the same manner as R corresponds to a second arbitrary layer having flakes capable of reflecting circularly polarized light with the same rotation direction as that of the circularly polarized light that the polarization separation layer 11 can reflect.

[0153] (observation) As shown in Figure 21, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. RThe display medium 30 was placed with the side facing up. The display set 2 consisting of the display medium 30 and the display article 20 was observed from above under non-polarized illumination. R , character layer B R , Character Layer E R and character layer M X was visible, but the character layer S L was not visible.

[0154] Thereafter, the display medium 30 was turned over and placed back on the display article 20, and the display set 2 was observed again. L , Character Layer E R and character layer M X was visible, but the character layer I R and character layer B R was not visible.

[0155] The results of Example 2 are summarized in Table 2 below. In the column of "Direction of Circularly Polarized Light that Can Be Reflected" in Table 2, the abbreviations "positive", "negative" and "negative" have the same meanings as in Table 1.

[0156] [Table 2]

[0157] [Comparative Example 1] (Display set description) Fig. 22 is a cross-sectional view showing a display set 3 produced in Comparative Example 1. As shown in Fig. 22, the display set 3 produced in Comparative Example 1 includes a display medium 40 and a display article 20. The display article 20 is the same as that in Example 1. In addition, the display medium 40 does not have a retardation layer 12 and has a character layer E. L Instead of the letter E R 1. Except for the formation of the display medium 10, this embodiment is the same as the display medium 10 of the first embodiment.

[0158] Specifically, the display medium 40 was manufactured by the following procedure. The cholesteric resin layer of the multilayer film manufactured in Manufacturing Example 1 was bonded to an optically isotropic support film (a polyvinyl chloride film) via an adhesive, and the base film of the multilayer film was peeled off. The letter "B" was printed on the cholesteric resin layer using the ink manufactured in Manufacturing Example 2, and dried to form a character layer B. R In addition, the letter "E" was printed on the support film using the ink produced in Production Example 2, and then dried to form a letter layer E. R This resulted in the formation of character layer B. R , a polarization separation layer 11 as a layer of a cholesteric resin, and a character layer E R A display medium 40 having the above in this order in the thickness direction was obtained.

[0159] (observation) As shown in Figure 22, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. R The display medium 40 was placed with the side facing up. The display set 3 consisting of the display medium 40 and the display article 20 was observed from above under non-polarized illumination. L , character layer B R and character layer M X was visible, but the character layer I R and character layer E R was not visible.

[0160] Thereafter, the display medium 40 was turned over and placed back on the display article 20, and the display set 3 was observed again. L , Character Layer E R and character layer M X was visible, but the character layer I R and character layer B R was not visible.

[0161] The results of Comparative Example 1 are summarized in Table 3 below. In the column of "Direction of Circularly Polarized Light that Can Be Reflected" in Table 3, the abbreviations "positive", "negative" and "negative" have the same meanings as in Table 1.

[0162] [Table 3]

[0163] [Comparative Example 2] (Display set description) FIG. 23 is a cross-sectional view that shows a schematic diagram of the display set 4 produced in Comparative Example 2. As shown in FIG. 23, the display set 4 produced in Comparative Example 2 includes a display medium 50 and a display article 20. The display article 20 is the same as that in Example 1. The display medium 50 includes a character layer E. R Instead of the letter E L 40 is formed, the display medium is the same as that of Comparative Example 1.

[0164] Character Layer E L The same procedure was repeated for the character layer E formed in Comparative Example 1, except that the ink produced in Production Example 3 was used instead of the ink produced in Production Example 2. R was formed in the same manner.

[0165] (observation) As shown in Figure 23, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. R The display medium 50 was placed with the side facing up. The display set 4 consisting of the display medium 50 and the display article 20 was observed from above under non-polarized illumination. L , character layer B R , Character Layer E L and character layer M X was visible, but the character layer I R was not visible.

[0166] Thereafter, the display medium 50 was turned over and placed back on the display article 20, and the display set 4 was observed again. L , Character Layer E L and character layer M X was visible, but the character layer I R and character layer B R was not visible.

[0167] The results of Comparative Example 2 are summarized in Table 4 below. In the column of "Direction of Circularly Polarized Light that Can Be Reflected" in Table 4, the abbreviations "positive", "negative" and "negative" have the same meanings as in Table 1.

[0168] [Table 4]

[0169] [Comparative Example 3] (Display set description) Fig. 24 is a cross-sectional view that shows a schematic diagram of a display set 5 produced in Comparative Example 3. As shown in Fig. 24, the display set 5 produced in Comparative Example 3 includes a display medium 60 and a display article 20. The display article 20 is the same as that in Example 1. The display medium 60 is the same as the display medium 10 in Example 1, except that the display medium 60 includes a circular polarizing filter 63 that is a combination of a linear polarizer 61 and a quarter-wave plate 62, instead of the multilayer substrate 13.

[0170] Specifically, the display medium 60 was manufactured by the following procedure. A slightly black circular polarizing filter 63 was prepared as described in Example 1 of Japanese Patent No. 5828182. This circular polarizing filter 63 was capable of transmitting right-handed circularly polarized light and absorbing left-handed circularly polarized light. The letter "B" was printed on the linear polarizer 61 of this circular polarizing filter 63 using the ink manufactured in Manufacturing Example 2, and then dried to form a character layer B. R In addition, the letter "E" was printed on the quarter-wave plate 62 using the ink produced in Production Example 3, and then dried to form a character layer E. L This resulted in the formation of character layer B. R , circular polarizing filter 63 and character layer E L A display medium 60 having the above in this order in the thickness direction was obtained.

[0171] (observation) As shown in Figure 24, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. R The display medium 60 was placed with the side facing up. The display set 5 consisting of the display medium 60 and the display article 20 was observed from above under non-polarized illumination. R , character layer B R and character layer M X was visible, but the character layer S L and character layer E L was not visible.

[0172] Thereafter, the display medium 60 was turned over and placed back on the display article 20, and the display set 5 was observed again. R , character layer S L , character layer B R , Character Layer E L and character layer M X Both were visible.

[0173] The results of Comparative Example 3 are summarized in Table 5 below. In the column of "Direction of Circularly Polarized Light that Can Be Reflected" in Table 5, the abbreviations "positive", "negative" and "negative" have the same meanings as in Table 1.

[0174] [Table 5]

[0175] [Comparative Example 4] (Display set description) FIG. 25 is a cross-sectional view that shows a schematic diagram of the display set 6 produced in Comparative Example 4. As shown in FIG. 25, the display set 6 produced in Comparative Example 4 includes a display medium 70 and a display article 20. The display article 20 is the same as that in Example 1. The display medium 70 includes a character layer E. L Instead of the letter E R4. The display medium is the same as the display medium 60 of Comparative Example 3, except that

[0176] Character Layer E R The same procedure was repeated for the character layer E formed in Comparative Example 3, except that the ink produced in Production Example 2 was used instead of the ink produced in Production Example 3. L was formed in the same manner.

[0177] (observation) As shown in Figure 25, character layer I R , character layer S L and character layer M X The display article 20 was placed on a table (not shown) so that the character layer B was facing upward. R The display medium 70 was placed with the side facing up. The display set 6 consisting of the display medium 70 and the display article 20 was observed from above under non-polarized illumination. R , character layer B R , Character Layer E R and character layer M X was visible, but the character layer S L was not visible.

[0178] Thereafter, the display medium 70 was turned over and placed back on the display article 20, and the display set 6 was observed again. R , character layer S L , character layer B R , Character Layer E R and character layer M X Both were visible.

[0179] The results of Comparative Example 4 are summarized in Table 6 below. In the column of "Direction of Circularly Polarized Light that Can Be Reflected" in Table 6, the abbreviations "positive", "negative" and "negative" have the same meanings as in Table 1.

[0180] [Table 6] [Explanation of symbols]

[0181] 100 Display media 110 Multi-layered substrate 110U Polarization separation layer side of multi-layer substrate 110D Retardation layer side of multi-layer substrate 111 Polarization separation layer 112 Retardation layer 120 First reflective layer 200 Display media 220 Second reflective layer 300 Display media 400 display sets 500 Displayed items 510 Underlying items 520 First display layer 530 Second display layer 540 Achiral Layer

Claims

1. A display set including a display medium and a display article, The display medium includes a multilayer substrate including a polarization separation layer and a retardation layer, and a first reflective layer provided on a part of a surface of the multilayer substrate facing the polarization separation layer, the first reflective layer is entirely overlapped with a part of the polarization separation layer and a part of the retardation layer of the multilayer base material when viewed in the thickness direction, The polarization separation layer has a rotation direction D Ａ It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The first reflective layer is oriented in one rotation direction D Ｂ１ It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The rotation direction D of the circularly polarized light that the polarization separation layer can reflect Ａ and the rotation direction D of the circularly polarized light that the first reflective layer can reflect. Ｂ１ And, The retardation layer is a display medium in which an in-plane retardation of the retardation layer at a measurement wavelength of 590 nm is equal to or greater than "{(2n+1) / 2}×590 nm-30 nm" and equal to or less than "{(2n+1) / 2}×590 nm+30 nm" (where n is an integer equal to or greater than 0), The display article includes a base article and a display layer provided on the base article, The display set is a display article in which the display layer can reflect circularly polarized light in one rotation direction D D and transmit circularly polarized light in the opposite rotation direction.

2. The display medium includes a second reflective layer provided on a surface of the multilayer substrate facing the retardation layer, The second reflective layer is oriented in one rotation direction D Ｂ２ It can reflect circularly polarized light in one direction and transmit circularly polarized light in the opposite direction. The rotation direction D of the circularly polarized light that the polarization separation layer can reflect Ａ and the rotation direction D of the circularly polarized light that the second reflective layer can reflect. Ｂ２ The display set of claim 1 , wherein: and are reversed.

3. The second reflective layer of the display medium is provided on a part of a surface of the multilayer substrate on the retardation layer side, The display set according to claim 2 , wherein the entire second reflective layer overlaps with a part of the polarization separation layer and a part of the retardation layer of the multilayer base material when viewed in the thickness direction.

4. The display set described in claim 1 or 2, wherein the display medium is a display set in which the first reflective layer contains flakes of a resin having cholesteric regularity.

5. The display set described in claim 2 or 3, wherein the display medium includes the second reflective layer containing flakes of a resin having cholesteric regularity.

6. A display set described in any one of claims 1 to 5, wherein the wavelength width of the wavelength range in which the polarization separation layer of the display medium can reflect circularly polarized light is 70 nm or more.

7. A display set described in any one of claims 1 to 6, wherein the polarization separation layer of the display medium is a layer of a resin having cholesteric regularity.

8. As a display layer of the display article, The rotation direction D of the circularly polarized light that the polarization separation layer can reflect Ａ The same rotation direction D Ｄ１ a first display layer that reflects circularly polarized light having a rotation direction of 1 and transmits circularly polarized light having an opposite rotation direction; The rotation direction D of the circularly polarized light that the polarization separation layer can reflect Ａ The opposite rotation direction D Ｄ２ and a second display layer capable of reflecting circularly polarized light having a rotation direction opposite to that of the first display layer and transmitting circularly polarized light having an opposite rotation direction.

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