Mid-air image formation device and laminate

Abstract

This mid-air image formation device 10a, 10b comprising a display part 1, a light transmission and image formation part 3, a light diffusion control part 2, and an adhesion layer 4, wherein the light transmission and image formation part 3 transmits light originating from the display part 1 and forms an image at a position on the surface side opposite from the display part 1, the light diffusion control part 2 diffuses or transmits light incident on the inside of the light diffusion control part 2 depending on the incident angle thereof, and has a louver-shaped regular internal structure comprising, within a region having a relatively low refractive index, a plurality of plate-shaped regions each having a relatively high refractive index, and the adhesion layer 4 comprises any one of an adhesive, a pressure-sensitive adhesive, and a hardenable pressure-sensitive adhesive, and the number of acidic groups present in the adhesion layer 4 with respect to all components constituting the adhesion layer 4 is 0.050 mmol / g or less. This mid-air image formation device 10a, 10b has excellent durability and makes it possible to satisfactorily view a mid-air image.

Description

Aerial image forming device and laminate

[0001] The present invention relates to an aerial image forming device and a laminate for forming the aerial image forming device.

[0002] Aerial images are images formed at any position in space by reflecting and refracting light emitted from a light source using optical elements. There is no screen or display at the position where the aerial image is displayed, so viewers who view the aerial image experience a mysterious sensation. For this reason, aerial images have been used in various applications in recent years, including virtual reality.

[0003] For example, Patent Document 1 discloses an aerial image forming device that includes at least a display unit and a light-transmitting imaging unit, in which an image (real image) displayed on the display unit is displayed as an aerial image primarily through the action of the light-transmitting imaging unit.

[0004] Japanese Patent Application Laid-Open No. 2020-060752

[0005] When an aerial image forming device is operated, an unintended image called a ghost image may be displayed simultaneously with the aerial image. The occurrence of a ghost image is unintended and cannot be said to accurately reflect the real image. In addition, the ghost image may overlap with the aerial image, making it difficult to clearly view the aerial image.

[0006] From the viewpoint of suppressing the occurrence of such ghost images, the inventors have found that the occurrence of ghost images can be effectively suppressed by providing a light diffusion control unit in the aerial image forming device that diffuses or transmits light depending on the angle of incidence. Specifically, the inventors have found that the occurrence of ghost images can be effectively suppressed by providing the light diffusion control unit on the display unit side of the light-transmitting image forming unit.

[0007] Furthermore, in an aerial image forming device, disturbance light caused by an external light source may be perceived along with the aerial image. For example, if the aerial image forming device is installed under a fluorescent lamp, the viewer may see disturbance light corresponding to the fluorescent lamp, which may interfere with the viewing of the aerial image.

[0008] Here, disturbance light is not simply light reflected from the surface of the translucent imaging unit, but light that penetrates the translucent imaging unit and returns to the observer. Because it causes color breakup due to diffraction, it significantly reduces visibility compared to the reflection of a general external light source.

[0009] Since aerial image forming devices are expected to be used in places where there are many external light sources, such as convenience stores, it is necessary to suppress the effects of ambient light such as that described above.

[0010] The inventors have found that the above-described light diffusion control unit is also effective in suppressing the generation of ambient light. That is, the inventors have found that providing the light diffusion control unit on the surface of the light-transmitting imaging unit opposite the display unit makes it possible to effectively suppress the generation of ambient light.

[0011] However, the inventors have discovered that a laminate formed by laminating a light diffusion control section on either side of a light-transmitting imaging section as described above is prone to the formation of air bubbles between the light-transmitting imaging section and the light diffusion control section when placed in a high-temperature environment or a high-temperature, high-humidity environment. The formation of such air bubbles is a major cause of impairment of the visibility of the aerial image.

[0012] The present invention has been made in consideration of the above-described situation, and aims to provide an aerial image forming device that is highly durable and allows aerial images to be clearly viewed, and a laminate for forming the aerial image forming device.

[0013] In order to achieve the above object, firstly, the present invention provides a display unit having a display surface and emitting light from the display surface, a light-transmitting image forming unit arranged on the display surface side of the display unit, a light diffusion control unit laminated on the side of the light-transmitting image forming unit opposite to the display unit or on the side of the light-transmitting image forming unit opposite to the display unit, and an adhesive layer laminated between the light-transmitting image forming unit and the light diffusion control unit and adhesively bonding the light-transmitting image forming unit and the light diffusion control unit, wherein the light-transmitting image forming unit transmits the light originating from the display surface and forms an image at a position on the side of the side opposite to the display unit. The present invention provides an aerial image forming device (Invention 1), wherein the light diffusion control section diffuses or transmits light incident thereon depending on the angle of incidence, and has a louvered regular internal structure with a plurality of plate-like regions with a relatively high refractive index within a region with a relatively low refractive index, the adhesion layer being composed of one of a pressure-sensitive adhesive, an adhesive, and a tacky adhesive, and the amount of acidic groups present in the adhesion layer relative to the total components constituting the adhesion layer is 0.050 mmol / g or less.

[0014] In the above invention (Invention 1), it is preferable that the amount of hydroxy groups present in the adhesive layer relative to the total components constituting the adhesive layer is 0.2 mmol / g or more and 20.0 mol / g or less (Invention 2).

[0015] In the above inventions (Inventions 1 and 2), it is preferable that the hydroxyl value of the components constituting the adhesion layer is 10 mgKOH / g or more and 500 mgKOH / g or less, and the acid value of the components constituting the adhesion layer is 0 mgKOH / g or more and 3.0 mgKOH / g or less (Invention 3).

[0016] In the above inventions (Inventions 1 to 3), it is preferable that the total light transmittance of the adhesive layer is 80% or more (Invention 4).

[0017] In the above inventions (Inventions 1 to 4), it is preferable that the display unit is arranged relative to the light diffusion control unit and the light-transmitting image forming unit so that the display surface and the surface of the light diffusion control unit opposite the light-transmitting image forming unit are non-parallel (Invention 5).

[0018] In the above inventions (Inventions 1 to 5), if a direction perpendicular to the longitudinal direction of the plate-shaped region and existing within the plane opposite the translucent imaging section in the light diffusion control section is defined as a first direction, it is preferable that each of the plate-shaped regions is inclined toward the first direction within the light diffusion control section (Invention 6).

[0019] In the above inventions (Inventions 1 to 6), it is preferable that the light-transmitting imaging unit includes a retrotransmitting optical element that retrotransmits incident light (Invention 7).

[0020] In the above invention (Invention 7), the retrotransmitting optical element is formed by stacking two layers each having a plurality of reflective surfaces, and in each of the two layers, the plurality of reflective surfaces are arranged perpendicular to one side of the retrotransmitting optical element and at a predetermined distance from each other, and it is preferable that the two layers are stacked so that the reflective surface in one layer is perpendicular to the reflective surface in the other layer (Invention 8).

[0021] Secondly, the present invention provides a laminate comprising: a translucent imaging section that forms an image of light incident from one side at a position on the other side; a light diffusion control section laminated on one side of the translucent imaging section; and an adhesion layer laminated between the translucent imaging section and the light diffusion control section and adhering the translucent imaging section and the light diffusion control section, wherein the light diffusion control section diffuses or transmits light incident into the light diffusion control section depending on the angle of incidence, and has a louvered regular internal structure with a plurality of plate-like regions with a relatively high refractive index within a region with a relatively low refractive index, and the adhesion layer is composed of one of a pressure-sensitive adhesive, an adhesive, and a pressure-sensitive adhesive, and the amount of acidic groups present in the adhesion layer relative to the total components constituting the adhesion layer is 0.050 mmol / g or less (Invention 9).

[0022] The aerial image forming device according to the present invention is excellent in durability and enables aerial images to be clearly viewed. Furthermore, the laminate according to the present invention makes it possible to form the above-described aerial image forming device.

[0023] FIG. 1 is a cross-sectional view schematically showing an example of an aerial image forming device according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of an aerial image forming device according to another embodiment of the present invention. FIG. 3 is a perspective view schematically showing the internal structure of a light diffusion control film. FIG. 4 is a diagram illustrating the relationship between the optical characteristics of a light diffusion control section and light that forms an aerial image and a ghost image. FIG. 5 is a photograph of a laminate taken in Test Example 2. FIG. 6 is a photograph of a laminate taken in Test Example 2. FIG. 7 is a photograph of a laminate taken in Test Example 2.

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The following describes embodiments of the present invention. [Aerial Image Forming Apparatus] Fig. 1 is a cross-sectional view showing an example of an aerial image forming apparatus according to this embodiment. Fig. 2 is a cross-sectional view showing an example of an aerial image forming apparatus according to another embodiment.

[0025] As shown in Figures 1 and 2, the aerial image forming devices 10a and 10b of this embodiment include a display unit 1 having a display surface and emitting light from the display surface, a light-transmitting imaging unit 3 arranged on the display surface side of the display unit 1, a light diffusion control unit 2 stacked on either or both of the side of the light-transmitting imaging unit 3 opposite the display unit 1 or the side of the light-transmitting imaging unit 3 facing the display unit 1, and an adhesion layer 4 stacked between the light-transmitting imaging unit 3 and the light diffusion control unit 2, which adheres the light-transmitting imaging unit 3 to the light diffusion control unit 2.

[0026] In particular, in the aerial image forming device 10a shown in Fig. 1, the light diffusion control unit 2 is stacked on the surface of the translucent image forming unit 3 opposite the display unit 1. In addition, in the aerial image forming device 10b shown in Fig. 2, the light diffusion control unit 2 is stacked on the surface of the translucent image forming unit 3 opposite the display unit 1.

[0027] The light-transmitting image forming unit 3 transmits light originating from the display surface and forms an image at a position on the surface opposite to the display unit 1. The light diffusion control unit 2 diffuses or transmits light incident on the light diffusion control unit 2 depending on the angle of incidence, and has a louver-like regular internal structure having a plurality of plate-like regions with a relatively high refractive index within a region with a relatively low refractive index. The adhesion layer 4 is composed of one of a pressure-sensitive adhesive, an adhesive, and a pressure-sensitive adhesive, and the amount of acidic groups present in the adhesion layer 4 relative to the total components constituting the adhesion layer 4 is 0.050 mmol / g or less.

[0028] 1. Effects (1) Suppression of ghost image generation In the aerial image forming device 10a (FIG. 1) in which the light diffusion control unit 2 is stacked on the surface side of the light-transmitting imaging unit 3 facing the display unit 1, the generation of ghost images can be effectively suppressed. The effects of this are described below.

[0029] FIG. 3 is a perspective view schematically illustrating the internal structure of the light diffusion control unit 2. As shown in FIG. 3, the light diffusion control unit 2 has a louvered, regular internal structure including multiple plate-like regions 201 with a relatively high refractive index within a region 202 with a relatively low refractive index. The regular internal structure of the light diffusion control unit 2 allows incident light incident on the surface of the light diffusion control unit 2 within a predetermined range of incident angles to be emitted while being strongly diffused with a predetermined opening angle. On the other hand, when the incident angle is outside the above-mentioned range, the light can be transmitted without being diffused or emitted with less diffusion than incident light within the above-mentioned range of incident angles. The direction perpendicular to the longitudinal direction of the plate-like region 201 and present on the surface of the light diffusion control unit 2 opposite the translucent imaging unit 3 (the direction indicated by "D1" in FIG. 3) is referred to as the "first direction."

[0030] In the aerial image forming device 10a according to this embodiment, when a desired image is displayed on the display surface of the display unit 1, an image (aerial image) formed by the real image being focused in the air can be seen at the position indicated by reference numeral "5" in Fig. 1 when viewed from a predetermined observation point 6. In this specification, the surface indicated by reference numeral "5" will be referred to as the "aerial image observation surface."

[0031] In conventional aerial image forming devices, an image known as a ghost image may also be displayed along with the aerial image. A ghost image is an image that reflects a displayed image and is displayed around the aerial image on the aerial image observation surface 5, even though it is not displayed on the display surface of the display unit 1. To suppress the occurrence of such ghost images, optical elements that block only the light that contributes to the formation of ghost images are sometimes used. However, because these optical elements block a portion of the light emitted from the display unit 1, they reduce the brightness of the aerial image, making it difficult for the viewer to view the aerial image.

[0032] In contrast, the aerial image forming device 10a according to this embodiment is equipped with the light diffusion control unit 2, and is therefore able to effectively suppress the occurrence of ghost images while maintaining sufficient brightness of the aerial image. As will be explained below, this effect is presumed to be due to the action of the light diffusion control unit 2. However, this effect is not limited to this action, and the possibility of other effects also exists.

[0033] FIG. 4 is a diagram for explaining the action of the light diffusion control unit 2, and in particular, a diagram for explaining the relationship between the optical characteristics of the light diffusion control unit 2 and the light that forms the aerial image and the ghost image.

[0034] As described above, the light diffusion control unit 2 diffuses and transmits light incident within a predetermined incident angle range, and transmits light incident outside this incident angle range with almost no diffusion. The graph in FIG. 4 shows the relationship between the incident angle of light incident on the light diffusion control unit 2 and the haze value. Specifically, it shows that for light incident from an incident angle range of approximately −10° to approximately 10°, the haze value exceeds 80% (i.e., the light is diffused and transmitted). On the other hand, it shows that for light incident from an incident angle range of approximately −70° to approximately −20°, the haze value is approximately 15% (i.e., the light is transmitted with almost no diffusion). The incident angle at which the haze value fluctuates significantly (near −15° in FIG. 4) is sometimes referred to as the “threshold value.”

[0035] Here, the "haze value" mentioned above differs from ordinary "haze" in that it is a measurement value obtained by placing a predetermined distance between the integrating sphere opening and the sample and varying the angle of incidence onto the sample. In the measurements herein, the predetermined distance is set to 20 mm, but the value is not particularly limited as long as it allows for confirmation of the straight transmission / diffuse transmission of incident light.

[0036] In the aerial image forming device 10a according to this embodiment, the light diffusion controller 2 exhibiting the above-described optical characteristics is located between the display unit 1 and the light-transmitting imaging unit 3. This allows the light for forming the aerial image to reach the light-transmitting imaging unit 3 in a satisfactory manner, while allowing the light for forming the ghost image to reach the light-transmitting imaging unit 3 in a diffused state. This allows the viewer to clearly view the aerial image while making it difficult to view the ghost image. Furthermore, because the light diffusion controller 2 controls the diffusion of light rather than blocking light, it is possible to display the aerial image with sufficient brightness while suppressing the occurrence of ghost images.

[0037] Furthermore, by appropriately adjusting the type of light diffusion control unit 2 and the stacking state with the light-transmitting imaging unit 3, etc., and adjusting the threshold value to be located between the range of incident angles of light for forming an aerial image and the range of incident angles of light for forming a ghost image, as shown in Figure 4, a better effect can be achieved.

[0038] (2) Suppression of the effects of ambient light In addition, in the aerial image forming device 10b (FIG. 2), in which the light diffusion control unit 2 is stacked on the side of the translucent imaging unit 3 opposite the display unit 1, the effects of ambient light can be effectively suppressed. This effect is described below.

[0039] As a result of various studies, the inventors have speculated that the above-mentioned ambient light is caused by light (hereinafter sometimes referred to as "return light") that is incident on the light-transmitting imaging unit 3 from an external light source and returns toward the viewer. In particular, when the light-transmitting imaging unit 3 is a retrotransmitting optical element (described later), the inventors speculated that such return light is light that is incident on the interior of the retrotransmitting optical element from an external light source, has its emission direction changed significantly within the retrotransmitting optical element, and is emitted from the surface on the viewer side.

[0040] The aerial image forming device 10b according to this embodiment is configured such that the light diffusion control unit 2 is provided on the viewer-facing surface of the light-transmitting imaging unit 3, so that light incident on the light-transmitting imaging unit 3 from an external light source is diffused and transmitted through the light diffusion control unit 2. This makes it possible to suppress color breakup while blurring the return light, improving visibility. On the other hand, the light originating from the display unit 1 is transmitted straight through the light diffusion control unit 2, allowing the aerial image to be clearly displayed. As a result, the aerial image forming device 10b according to this embodiment can suppress the return light and reduce the effects of ambient light, thereby enabling the aerial image to be clearly viewed.

[0041] (3) Durability The aerial image forming devices 10a and 10b according to this embodiment have excellent durability due to the presence of the aforementioned adhesive layer 4 between the light diffusion control section 2 and the light-transmitting image forming section 3.

[0042] In conventional aerial image forming devices, the light diffusion control unit, the translucent imaging unit, and other components are often fixed together with a common adhesive layer. In this case, if the aerial image forming device is placed in a high-temperature or high-temperature, high-humidity environment for a long period of time, numerous air bubbles may form in the laminate composed of the light diffusion control unit, the translucent imaging unit, etc. In an aerial image forming device with such air bubbles, the visibility of the aerial image is significantly reduced. The inventors believe that such air bubbles are caused by gas generated from the translucent imaging unit due to placement in a high-temperature environment.

[0043] Furthermore, the aerial image forming devices 10a and 10b according to the present embodiment are configured such that at least the light diffusion control section 2 and the light-transmitting image forming section 3 are fixed by the adhesive layer 4 that satisfies the aforementioned condition regarding the amount of acidic groups, thereby suppressing gas generated from the light-transmitting image forming section and preventing the generation of bubbles, even when the devices are left in a high-temperature environment or a high-temperature, high-humidity environment for a long period of time. As a result, the aerial image forming devices 10a and 10b according to the present embodiment maintain excellent visibility.

[0044] 2. Display Unit The display unit 1 constituting the aerial image forming devices 10a, 10b according to the present embodiment is not particularly limited as long as it has a display surface and is capable of displaying an image on the display surface and emitting the light toward the light diffusion control unit 2 and the translucent imaging unit 3. For example, the display unit 1 can be a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, or the like.

[0045] The positional relationship between the display unit 1 and the light diffusion control unit 2, the translucent image forming unit 3, and the adhesive layer 4 is not particularly limited. As shown in Figures 1 and 2, it is preferable that the display unit 1, the light diffusion control unit 2, etc. are sufficiently separated, and that a space exists between them. It is also preferable that the display unit 1 is disposed relative to the light diffusion control unit 2, the translucent image forming unit 3, and the adhesive layer 4 so that the display surface of the display unit 1 and the surface of the light diffusion control unit 2 opposite to the translucent image forming unit 3 are non-parallel. This positional relationship makes it possible to display an aerial image more clearly.

[0046] 3. Light Diffusion Control Unit The light diffusion control unit 2 constituting the aerial image forming devices 10a and 10b according to this embodiment is not particularly limited as long as it has the above-described louver-like regular internal structure.

[0047] From the viewpoint of facilitating the formation of the regular internal structure, it is preferable that the light diffusion control portions 2 are formed by curing a composition for light diffusion control portions containing a high refractive index component and a low refractive index component having a refractive index lower than that of the high refractive index component. In particular, it is preferable that the high refractive index component and the low refractive index component each have one or two polymerizable functional groups.

[0048] From the perspective of the SDGs, the material that constitutes the light diffusion control unit 2 may be a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material.

[0049] (1) High Refractive Index Component Preferred examples of the high refractive index component include (meth)acrylic acid esters containing an aromatic ring, and particularly preferred are (meth)acrylic acid esters containing multiple aromatic rings. Examples of (meth)acrylic acid esters containing multiple aromatic rings include biphenyl (meth)acrylate, naphthyl (meth)acrylate, anthracyl (meth)acrylate, benzylphenyl (meth)acrylate, biphenyloxyalkyl (meth)acrylate, naphthyloxyalkyl (meth)acrylate, anthracyloxyalkyl (meth)acrylate, benzylphenyloxyalkyl (meth)acrylate, and the like, as well as those partially substituted with halogen, alkyl, alkoxy, alkyl halide, or the like. Among these, biphenyl (meth)acrylate is preferred from the viewpoint of ease of forming a good regular internal structure, and specifically, o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, and the like are preferred. Note that, in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0050] The molecular weight of the high refractive index component is preferably 150 to 2500, particularly preferably 200 to 1500, and even more preferably 250 to 1000. This facilitates the formation of a light diffusion control section 2 having a desired regular internal structure. Note that, if the theoretical molecular weight of the high refractive index component can be determined based on its molecular structure, the molecular weight of the high refractive index component refers to this theoretical molecular weight. On the other hand, if the theoretical molecular weight is difficult to determine because the high refractive index component is, for example, a polymer component, the molecular weight of the high refractive index component refers to the weight-average molecular weight obtained as a value converted into standard polystyrene measured by gel permeation chromatography (GPC). Note that, in this specification, the measurement method for weight-average molecular weight refers to the value converted into standard polystyrene measured by the GPC method.

[0051] The refractive index of the high refractive index component is preferably 1.45 to 1.70, more preferably 1.50 to 1.65, particularly preferably 1.54 to 1.62, and even more preferably 1.56 to 1.59. This makes it easier to form a light diffusion control portion 2 having a desired regular internal structure. Note that the refractive index in this specification means the refractive index of a predetermined component before curing the composition for light diffusion control portion, and this refractive index is measured in accordance with JIS K0062:1992.

[0052] The content of the high refractive index component in the composition for light diffusion control portions is preferably 25 to 400 parts by mass, more preferably 50 to 350 parts by mass, particularly preferably 75 to 300 parts by mass, and even more preferably 100 to 200 parts by mass, relative to 100 parts by mass of the low refractive index component. This allows the regions derived from the high refractive index component and the regions derived from the low refractive index component to be present in a desired ratio in the regular internal structure of the formed light diffusion control portions 2, making it easier to form the desired regular internal structure.

[0053] (2) Low refractive index component Preferred examples of the low refractive index component include urethane (meth)acrylate, (meth)acrylic polymers having (meth)acryloyl groups in their side chains, (meth)acryloyl group-containing silicone resins, and unsaturated polyester resins. Among these, it is particularly preferable to use urethane (meth)acrylate because it is easy to form a good regular internal structure. More specifically, it is preferable to use urethane (meth)acrylate formed from (a) a compound containing at least two isocyanate groups, (b) a polyalkylene glycol, and (c) a hydroxyalkyl (meth)acrylate.

[0054] Preferred examples of the (a) compound containing at least two isocyanate groups include aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and biurets and isocyanurates thereof, as well as adducts which are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, alicyclic polyisocyanates are preferred, and alicyclic diisocyanates are particularly preferred.

[0055] Preferred examples of the polyalkylene glycol (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol, etc., and among these, polypropylene glycol is preferred. The weight-average molecular weight of the polyalkylene glycol (b) is preferably 2,300 to 19,500, more preferably 3,000 to 14,300, and even more preferably 4,000 to 12,300.

[0056] Preferred examples of the (c) hydroxyalkyl(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 3-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate, and among these, 2-hydroxyethyl(meth)acrylate is preferred.

[0057] The synthesis of a urethane (meth)acrylate using the above-mentioned components (a) to (c) as materials can be carried out according to a conventional method. In this case, from the viewpoint of efficiently synthesizing the urethane (meth)acrylate, the blending ratio of components (a) to (c) is preferably component (a):component (b):component (c)=1-5:1:1-5, and particularly preferably 1-3:1:1-3.

[0058] The weight average molecular weight of the low refractive index component is preferably 3,000 to 20,000, particularly preferably 5,000 to 15,000, and further preferably 7,000 to 13,000. This makes it easier to form the light diffusion controlling parts 2 having a desired regular internal structure.

[0059] The refractive index of the low refractive index component is preferably 1.30 to 1.59, more preferably 1.38 to 1.50, particularly preferably 1.42 to 1.49, and even more preferably 1.46 to 1.48 or less, which makes it easier to form the light diffusion control portion 2 having a desired regular internal structure.

[0060] (3) Other Additives The composition for light diffusion control portion described above may contain other additives in addition to the high refractive index component and the low refractive index component. Examples of the other additives include a polyfunctional monomer, a photopolymerization initiator, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, an oxygen absorber, a plasticizer, a diluting solvent, and a leveling agent.

[0061] Among the above, the composition for the light diffusion controlling portion preferably contains a photopolymerization initiator, which makes it easier to efficiently form the light diffusion controlling portion 2 having a desired regular internal structure.

[0062] Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2- propyl ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane], etc. These may be used alone or in combination of two or more.

[0063] When a photopolymerization initiator is used, the content of the photopolymerization initiator in the composition for light diffusion control portion is preferably 0.2 to 20 parts by mass, more preferably 0.5 to 16 parts by mass, particularly preferably 1 to 13 parts by mass, and even more preferably 4 to 10 parts by mass, relative to 100 parts by mass of the total amount of the high refractive index component and the low refractive index component. This makes it easy to efficiently form the light diffusion control portion 2 having the desired regular internal structure.

[0064] (4) Preparation of composition for light diffusion control portion The composition for light diffusion control portion can be prepared by uniformly mixing the high refractive index component and the low refractive index component described above, and, if desired, other additives such as a photopolymerization initiator and an ultraviolet absorber.

[0065] During the mixing, a uniform composition for controlling light diffusion may be obtained by stirring while heating to a temperature of 40 to 80° C. Furthermore, a dilution solvent may be added and mixed so that the resulting composition for controlling light diffusion has a desired viscosity.

[0066] (5) Regular internal structure As described above, it is preferable that the light diffusion control section 2 has a louver-like regular internal structure having a plurality of plate-like regions 201 with a relatively high refractive index within a region 202 with a relatively low refractive index.

[0067] 3, it is preferable that each of the plate-like regions 201 in the light diffusion control unit 2 is inclined toward the first direction D1 within the light diffusion control unit 2. This makes it easier for the aerial image forming device 10 according to this embodiment to suppress the occurrence of ghost images or ambient light, and to display brighter aerial images.

[0068] When the plate-like region 201 is inclined as described above, the angle of inclination relative to the thickness direction of the light diffusion control unit 2 is preferably 0° to 30°, more preferably 1° to 20°, particularly preferably 2° to 15°, and even more preferably 3° to 10°. This makes it easier for the aerial image forming device 10 according to this embodiment to suppress the occurrence of ghost images or ambient light, and to display brighter aerial images.

[0069] The light diffusion control unit 2 may have a structure other than the regular internal structure as shown in Fig. 3. For example, the plate-like region 201 may be bent partway along the thickness direction of the light diffusion control unit 2. Furthermore, the light diffusion control unit 2 may have two or more stacked layers each having a regular internal structure in which the plate-like regions 201 are arranged.

[0070] (6) Thickness of Light Diffusion Control Unit The thickness of the light diffusion control unit 2 is preferably 1 to 500 μm, more preferably 10 to 300 μm, particularly preferably 50 to 250 μm, and even more preferably 80 to 200 μm. This makes it easier for the aerial image forming device 10 according to this embodiment to suppress the occurrence of ghost images or ambient light, and to display brighter aerial images.

[0071] (7) Method for Forming the Light Diffusion Control Parts The method for forming the light diffusion control parts 2 is not particularly limited, and they can be formed by a conventionally known method.

[0072] For example, the composition for light diffusion control portion described above is applied to one side of a process sheet to form a coating film, and then one side (particularly the release side) of a release sheet is laminated to the side of the coating film opposite the process sheet. Subsequently, the coating film is irradiated with active energy rays through the process sheet or the release sheet to cure it, thereby forming the light diffusion control portion 2. In this way, by laminating the release sheet on the coating film, a gap between the release sheet and the process sheet is maintained, preventing the coating film from being crushed, and making it easier to form a light diffusion control portion 2 having a uniform thickness and a desired regular internal structure.

[0073] Examples of the release sheet include resin films such as polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these may also be used. Furthermore, laminated films of these may also be used. From the perspective of the SDGs, the material constituting the release sheet may be a material with a high biomass content, a recyclable or reusable material, or a recycled or reused material.

[0074] The release surface of the release sheet is preferably subjected to a release treatment. Preferred examples of the release agent used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

[0075] The thickness of the release sheet is not particularly limited, but from the viewpoint of excellent handling and of being able to well protect the light diffusion control portion until use, it is preferably 20 to 200 μm, more preferably 30 to 100 μm.

[0076] The process sheet can be the resin film, crosslinked film, or laminated film thereof used as the release sheet described above. The release sheet described above can also be used as the process sheet.

[0077] The thickness of the process sheet is preferably 20 to 250 μm, more preferably 30 to 200 μm, from the viewpoint of facilitating the formation of the desired light diffusion control portions and of being able to adequately protect the light diffusion control portions until use.

[0078] Examples of the coating method include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. The composition for light diffusion control portion may be diluted with a solvent as needed.

[0079] The coating film can be irradiated with active energy rays by a conventionally known method. For example, a linear light source is used as a light source of active energy rays, and the surface of the target is irradiated with band-like (almost linear) light that is random in the width direction (TD direction) and approximately parallel in the flow direction (MD direction). Note that the inclination angle of the plate-like region 201 can also be adjusted by adjusting the irradiation angle of the light.

[0080] The active energy rays refer to electromagnetic waves or charged particle rays that have an energy quantum, and specific examples include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle and can easily form a desired regular internal structure.

[0081] When ultraviolet rays are used as the active energy rays, the irradiation conditions are such that the peak irradiance on the coating surface is 0.1 to 200 mW / cm ２ Furthermore, it is preferable that the integrated light amount on the coating surface is 5 to 300 mJ / cm ２Furthermore, the relative moving speed of the light source of the active energy rays with respect to the object to be irradiated is preferably 0.1 to 10 m / min.

[0082] From the viewpoint of completing the curing more reliably, it is also preferable to irradiate the cured product with normal active energy rays (active energy rays that have not been converted into parallel light or band-like light, or scattered light) after curing using the band-like light as described above.

[0083] The light-transmitting imaging unit 3 constituting the aerial image forming devices 10 a, 10 b according to the present embodiment is not particularly limited as long as it can transmit light originating from the display unit 1 and form an aerial image on a predetermined aerial image observation plane. An example of such a light-transmitting imaging unit 3 is a retrotransmitting optical element that retrotransmits incident light.

[0084] Although conventionally known retrotransmitting optical elements can be used, from the viewpoint of facilitating good aerial image formation, a retrotransmitting optical element having a two-sided orthogonal reflector array structure or a retrotransmitting optical element having a two-sided corner reflector array structure is preferred, and a retrotransmitting optical element having a two-sided orthogonal reflector array structure is more preferred. Examples of retrotransmitting optical elements having a two-sided orthogonal reflector array structure include those described in Japanese Patent No. 5,085,631. That is, as a retrotransmitting optical element having a two-sided orthogonal reflector array structure, it is preferable to use a retrotransmitting optical element formed by stacking two layers each having a plurality of reflective surfaces. In particular, in the retrotransmitting optical element, it is preferable that in each of the two layers, a plurality of reflective surfaces are arranged perpendicular to one surface of the retrotransmitting optical element and at a predetermined interval from each other, and that the two layers are stacked so that the reflective surface in one layer is perpendicular to the reflective surface in the other layer. Specifically, a retrotransmitting optical element having a dihedral corner reflector array structure may have the structure described in International Publication WO2007 / 116639.

[0085] The thickness of the light-transmitting imaging unit 3 is preferably 0.1 to 20 mm, more preferably 0.5 to 15 mm, particularly preferably 1 to 12 mm, even more preferably 2 to 10 mm, and most preferably 4 to 8 mm, which makes it easier for the aerial image forming devices 10a, 10b according to this embodiment to suppress the occurrence of ghost images or ambient light and to display brighter aerial images.

[0086] 5. Adhesion Layer The details of the adhesion layer 4 in the present embodiment are not particularly limited as long as the adhesion layer 4 is composed of any one of a pressure-sensitive adhesive, an adhesive, and a pressure-sensitive adhesive, and the amount of acidic groups present in the adhesion layer 4 relative to the total components constituting the adhesion layer 4 is 0.050 mmol / g or less.

[0087] From the viewpoint of making it easier to effectively suppress the generation of bubbles, the amount of the acidic groups is preferably 0.040 mmol / g or less, more preferably 0.030 mmol / g or less, particularly preferably 0.020 mmol / g or less, further preferably 0.010 mmol / g or less, and preferably 0.001 mmol / g or less, with the lower limit being most preferably 0 mmol / g.

[0088] Furthermore, from the viewpoint of effectively suppressing the generation of bubbles, the amount of hydroxy groups present in the adhesion layer 4 relative to the total components constituting the adhesion layer 4 is preferably 0.2 to 20.0 mmol / g, more preferably 0.3 to 10.0 mmol / g, and even more preferably 0.4 to 5.0 mmol / g.

[0089] Here, the amount of acidic groups and the amount of hydroxyl groups in this specification are theoretical values ​​derived from the components that constitute the adhesive layer.

[0090] Furthermore, from the viewpoint of making it easier to achieve the amount of acidic groups described above, the hydroxyl value of the components constituting the adhesion layer 4 is preferably 10 to 500 mgKOH / g, more preferably 30 to 350 mgKOH / g or more, particularly preferably 50 to 200 mgKOH / g, even more preferably 60 to 150 mgKOH / g, and especially preferably 70 to 120 mgKOH / g.

[0091] Furthermore, from the viewpoint of making it easier to achieve the amount of acidic groups described above, the acid value of the components constituting the adhesion layer 4 is preferably 3.0 mgKOH / g or less, more preferably 2.5 mgKOH / g or less, particularly preferably 2.0 mgKOH / g or less, and even more preferably 1.0 mgKOH / g or less, and of these, preferably 0.1 mgKOH / g or less, with the lower limit being most preferably 0 mgKOH / g.

[0092] Here, the hydroxyl value and acid value in this specification are basically theoretical values ​​derived from the components constituting the adhesive layer, and when such theoretical values ​​cannot be derived, values ​​measured in accordance with JIS K0070 are used.

[0093] (1) Pressure-sensitive adhesive layer The adhesive layer 4 in this embodiment is preferably a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, from the viewpoint of easily achieving the above-mentioned condition regarding the amount of acidic groups and easily achieving the desired adhesion.

[0094] The pressure-sensitive adhesive is not particularly limited, but is preferably transparent from the viewpoint of facilitating good visibility of the aerial image. Specific examples of the pressure-sensitive adhesive include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and polyester pressure-sensitive adhesives. However, acrylic pressure-sensitive adhesives are preferred from the viewpoint of easily achieving the desired adhesive strength and transparency. The pressure-sensitive adhesive may be a solvent-based pressure-sensitive adhesive, a solventless pressure-sensitive adhesive, or an emulsion-based pressure-sensitive adhesive. From the viewpoint of the SDGs, the material constituting the pressure-sensitive adhesive may be a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material.

[0095] The acrylic adhesive is preferably formed from an adhesive composition containing a (meth)acrylic acid ester polymer as a main component, and more preferably from an adhesive composition containing a (meth)acrylic acid ester polymer and a crosslinking agent. In this specification, "(meth)acrylic acid ester" refers to both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0096] (1-1) (Meth)acrylic Acid Ester Polymer From the viewpoint of easily exhibiting a desired adhesive strength (particularly from the viewpoint of adhesion to an adherend such as a light diffusion control unit or a light-transmitting image forming unit), the (meth)acrylic acid ester polymer preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer, and particularly preferably contains a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms.

[0097] Examples of (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, etc. Among these, from the viewpoints of further improving adhesion and suppressing bubbles, (meth)acrylic acid esters having an alkyl group containing 1 to 8 carbon atoms are preferred, and it is preferable to use at least one of methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.

[0098] From the viewpoint of improving adhesiveness and suppressing foaming at the interface with the adherend, and from the viewpoint of being able to introduce suitable amounts of other monomer components such as reactive functional group-containing monomers into the (meth)acrylic acid ester polymer, the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferably contained in an amount of 50 to 99.9 mass %, more preferably 60 to 99 mass %, particularly preferably 70 to 95 mass %, and even more preferably 75 to 90 mass % as a monomer unit constituting the polymer.

[0099] It is also preferable that the (meth)acrylic acid ester polymer contains, as a monomer unit constituting the polymer, a reactive functional group-containing monomer having a reactive functional group in the molecule. In particular, when the pressure-sensitive adhesive composition contains a crosslinking agent, the reactive functional group of the reactive functional group-containing monomer reacts with the crosslinking agent, making it easier to control the cohesive strength of the resulting pressure-sensitive adhesive. This makes it easier for the resulting pressure-sensitive adhesive layer to exhibit the desired adhesive strength.

[0100] Preferred examples of reactive functional group-containing monomers include monomers having a hydroxy group in the molecule (hydroxy group-containing monomers), monomers having a carboxy group in the molecule (carboxy group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers). Among these, hydroxy group-containing monomers or carboxy group-containing monomers are preferred, and hydroxy group-containing monomers are particularly preferred. These reactive functional group-containing monomers may be used alone or in combination of two or more.

[0101] Examples of hydroxy group-containing monomers include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, it is preferable to use 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate, and it is more preferable to use 2-hydroxyethyl (meth)acrylate. These may be used alone or in combination of two or more.

[0102] Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, etc. These may be used alone or in combination of two or more.

[0103] Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0104] The (meth)acrylic acid ester polymer preferably contains, as a monomer unit constituting the polymer, 0.1 to 50 mass %, more preferably 1 to 50 mass %, particularly preferably 4 to 40 mass %, even more preferably 8 to 30 mass %, and of these, preferably 12 to 25 mass % of the reactive functional group-containing monomer. This makes it easier to improve the adhesiveness of the resulting pressure-sensitive adhesive, makes it easier for the pressure-sensitive adhesive layer to exhibit the desired adhesive strength, and makes it easier to suppress foaming at the interface with the adherend.

[0105] The (meth)acrylic acid ester polymer also preferably contains a nitrogen-atom-containing monomer as a monomer unit constituting the polymer. The presence of the nitrogen-atom-containing monomer as a constituent unit in the polymer imparts a predetermined polarity to the adhesive, thereby making it possible to provide excellent affinity for adherends having a certain degree of polarity, such as glass. The nitrogen-atom-containing monomer is preferably a monomer having a nitrogen-containing heterocycle, from the viewpoint of providing the (meth)acrylic acid ester polymer with appropriate rigidity. Furthermore, from the viewpoint of increasing the degree of freedom of the nitrogen-atom-containing monomer-derived portion in the higher-order structure of the adhesive, it is preferable that the nitrogen-atom-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used in polymerization to form the (meth)acrylic acid ester polymer.

[0106] Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine is preferred, as it exhibits superior adhesive strength. These may be used alone or in combination of two or more.

[0107] When the (meth)acrylic acid ester polymer contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the nitrogen atom-containing monomer is preferably contained in an amount of 0.1 to 30 mass %, more preferably 0.5 to 20 mass %, particularly preferably 1 to 15 mass %, and even more preferably 3 to 10 mass %. This makes it easier for the resulting pressure-sensitive adhesive to exhibit excellent adhesive strength even to polar adherends, and also makes it easier to suppress foaming at the interface with the adherend.

[0108] The (meth)acrylic acid ester polymer may be a copolymer of the above-mentioned (meth)acrylic acid alkyl ester, reactive functional group-containing monomer, etc. with other monomers. As the other monomer, a monomer that does not contain a reactive functional group is preferred so as not to inhibit the above-mentioned action of the reactive functional group-containing monomer. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more. Furthermore, the polymerization mode of the polymer may be a random copolymer or a block copolymer. Furthermore, the polymer may be used alone or in combination of two or more.

[0109] The weight average molecular weight of the (meth)acrylic acid ester polymer is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,400,000, particularly preferably 200,000 to 1,800,000, further preferably 300,000 to 1,200,000, and of these, preferably 400,000 to 750,000. This improves the cohesive strength of the resulting pressure-sensitive adhesive, making it easier for the resulting pressure-sensitive adhesive layer to exhibit the desired adhesive strength and to suppress foaming at the interface with the adherend.

[0110] (1-2) Crosslinking Agent The crosslinking agent may be any that reacts with the reactive functional groups possessed by the (meth)acrylic acid ester polymer, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. Among the above, it is preferable to use an isocyanate-based crosslinking agent that has excellent reactivity with hydroxy groups and carboxy groups, or an epoxy-based crosslinking agent that has excellent reactivity with carboxy groups. The crosslinking agents may be used alone or in combination of two or more.

[0111] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret and isocyanurate forms thereof, as well as adducts thereof that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxy groups.

[0112] Preferred examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine.

[0113] The content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.02 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, particularly preferably 0.08 to 5 parts by mass, and even more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer. This makes it easier for the resulting pressure-sensitive adhesive to have favorable physical properties, adhesive strength, etc., and also makes it easier to suppress foaming at the interface with the adherend.

[0114] (1-3) Various Additives If desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as ultraviolet absorbers, silane coupling agents, photopolymerization initiators, antistatic agents, infrared absorbers, rust inhibitors, colorants, oxygen absorbers, surfactants, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive index adjusters, may be added to the pressure-sensitive adhesive composition described above.

[0115] Among the additives described above, it is preferable to use an ultraviolet absorber. By using an ultraviolet absorber, the formed pressure-sensitive adhesive layer has better durability. Preferred examples of ultraviolet absorbers include benzotriazole-based, benzophenone-based, benzoate-based, benzoxazinone-based, triazine-based, phenyl salicylate-based, cyanoacrylate-based, and nickel complex salt-based compounds. These may be used alone or in combination of two or more.

[0116] The content of the ultraviolet absorber in the pressure-sensitive adhesive composition is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, particularly preferably 1 to 10 parts by mass, and even more preferably 2 to 5 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer, which provides a pressure-sensitive adhesive layer having superior durability.

[0117] Among the additives described above, it is also preferable to use a silane coupling agent, which improves adhesion to the adherend, whether the adherend is a plastic plate or a glass member, and further improves the durability described above.

[0118] The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth)acrylic acid ester polymer and has optical transparency.

[0119] Examples of such silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; epoxy structure-containing silicon compounds such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. , 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and other amino group-containing silicon compounds, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, and condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used alone or in combination of two or more.

[0120] The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.01 to 2 parts by mass, more preferably 0.04 to 1 part by mass or more, particularly preferably 0.08 to 0.6 parts by mass, and even more preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer. This improves adhesion to the adherend, whether the adherend is a plastic plate or a glass member, and further improves the durability described above.

[0121] (1-4) Preparation of Adhesive Composition The above-mentioned adhesive composition can be prepared by mixing the (meth)acrylic acid ester polymer, the crosslinking agent, and other additives.

[0122] The (meth)acrylic acid ester polymer can be produced by polymerizing a mixture of monomer units constituting the polymer using a conventional radical polymerization method. Polymerization of the (meth)acrylic acid ester polymer can be carried out by solution polymerization or the like, optionally using a polymerization initiator. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of these may be used in combination. Examples of polymerization initiators include azo compounds and organic peroxides, and two or more of these may be used in combination. In the polymerization step, the weight-average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

[0123] After the (meth)acrylic acid ester polymer is obtained, a crosslinking agent and, if desired, other additives are added to the solution of the (meth)acrylic acid ester polymer, and the mixture is thoroughly mixed to obtain a pressure-sensitive adhesive composition (coating solution) diluted with a solvent.

[0124] Examples of dilution solvents that can be used to dilute the pressure-sensitive adhesive composition to prepare a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0125] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be appropriately selected depending on the situation. For example, the pressure-sensitive adhesive composition is diluted to a concentration of 10 to 40 mass %. Note that the addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and as long as the pressure-sensitive adhesive composition has a viscosity that allows coating, the addition of a dilution solvent is not necessary.

[0126] (1-5) Formation of Pressure-Sensitive Adhesive Layer The pressure-sensitive adhesive layer is preferably made of a pressure-sensitive adhesive obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition. Crosslinking of the pressure-sensitive adhesive composition can usually be carried out by heat treatment. This heat treatment can also serve as a drying treatment for volatilizing diluent solvents and the like from the coating layer of the pressure-sensitive adhesive composition applied to the desired object.

[0127] The heating temperature for the heat treatment is preferably 50 to 150° C., and particularly preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

[0128] After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (e.g., 23°C, 50% RH), if necessary. If this curing period is required, the PSA is formed after the curing period has elapsed; if no curing period is required, the PSA is formed after the heat treatment has been completed. In this specification, "relative humidity α%" may also be expressed as "α% RH" (RH; Relative humidity).

[0129] The above heat treatment (and curing) allows the (meth)acrylic acid ester polymer to be sufficiently crosslinked via the crosslinking agent.

[0130] (2) Adhesive Layer and Pressure-Sensitive Adhesive Layer As described above, the adhesion layer 4 in the present embodiment may be an adhesive layer made of an adhesive, or may be a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive. These adhesives and pressure-sensitive adhesive layers are not particularly limited as long as they satisfy the above-mentioned condition regarding the amount of acidic groups, and general adhesives can be used.

[0131] (3) Total Light Transmittance of Adhesion Layer The total light transmittance of the adhesion layer 4 in this embodiment is preferably 80% or more, particularly preferably 85% or more, and even more preferably 90% or more. The upper limit of the total light transmittance is not particularly limited, but is preferably 100%. This makes it easier to view the aerial image clearly. Details of the method for measuring the total light transmittance are as described in the test examples below.

[0132] (4) Thickness of Adhesion Layer In this embodiment, the thickness of the adhesion layer 4 is preferably 1 to 100 μm, more preferably 3 to 80 μm, particularly preferably 5 to 60 μm, even more preferably 7 to 40 μm, and most preferably 9 to 20 μm. This facilitates good adhesion between the light diffusion control unit 2 and the light-transmitting imaging unit 3, and facilitates effective suppression of air bubble generation.

[0133] 6. Other Components The aerial image forming devices 10a, 10b according to the present embodiment may include components other than the above-described display unit 1, light diffusion control unit 2, translucent image forming unit 3, and adhesive layer 4. In particular, the aerial image forming device 10 according to the present embodiment preferably includes a housing for fixing and accommodating the display unit 1, light diffusion control unit 2, translucent image forming unit 3, and adhesive layer 4 in predetermined positions.

[0134] The material, shape, dimensions, etc. of the housing can be appropriately selected depending on the application and purpose. In particular, it is preferable that the housing is made of a light-blocking material, which can prevent unintended leakage of light from the display unit 1 to the outside and can prevent unintended intrusion of external light into the optical path from the display unit 1 to the light diffusion control unit 2 or the light-transmitting imaging unit 3.

[0135] 7. Positional Relationship of Elements In the aerial image forming devices 10a and 10b according to the present embodiment, assuming a first direction indicated by "D1" in FIG. 3 and a second direction parallel to a plane perpendicular to both the display surface of the display unit 1 and one side of the light diffusion control unit 2, and located within the plane of the light diffusion control unit 2 opposite the light-transmitting image forming unit 3, it is preferable that the acute angle formed between the first direction and the second direction be greater than or equal to 0° and less than or equal to 90°. Regardless of the acute angle, by considering the angle of incidence to the light diffusion control unit 2 within a plane that includes D1 and is perpendicular to the light diffusion control unit 2, the aerial image forming devices 10a and 10b according to the present embodiment can more easily suppress the occurrence of ghost images or ambient light and can more easily display brighter aerial images.

[0136] Furthermore, when the aerial image forming devices 10a and 10b according to this embodiment are equipped with the aforementioned retrotransmissive optical element having a two-sided corner reflector array structure as the light-transmitting imaging unit 3, or a retrotransmissive optical element consisting of two layers each having multiple reflective surfaces stacked together, it is also preferable that the following conditions be satisfied.

[0137] First, assume a plane F that is perpendicular to both the surface of the light-transmitting imaging unit 3 opposite the light diffusion control unit 2 and the display surface of the display unit 1 and that passes through the center point of the light-transmitting imaging unit 3. Also, the width of the light-transmitting imaging unit 3 in a cross section obtained by cutting the light-transmitting imaging unit 3 along the plane F is defined as width W.

[0138] Furthermore, an observation point that exists within the plane F is assumed to satisfy both the following conditions A and B. (Condition A) If the angle between the line segment connecting the observation point and the center point and the surface of the translucent imaging unit 3 opposite to the light diffusion control unit 2 is defined as angle α, and the angle between the plane including the display surface of the display unit 1 and the plane including the surface of the translucent imaging unit 3 opposite to the light diffusion control unit 2 is defined as angle β, the sum of angles α and β is 90°. (Condition B) The distance between the observation point and the center point is 1 to 10 times the width W.

[0139] As a supplementary note, the above condition A means that the position of the observation point is determined depending on the positional relationship between the display unit 1 and the light-transmitting imaging unit 3 in the aerial image forming device 10. For example, for an aerial image forming device 10 in which the display unit 1 and the light-transmitting imaging unit 3 are arranged so that the angle β is 45°, the angle α related to the observation point is 45°, and for an aerial image forming device 10 in which the angle β is 60°, the angle α related to the observation point is 30°.

[0140] Furthermore, with regard to the above condition B, the expression "1 to 10 times the width W" means that the observation point only needs to satisfy the condition of any one point within this range. In particular, it is preferable that condition B be "the distance between the observation point and the center point is 3.5 times the width W."

[0141] It is preferable that each element of the aerial image forming device 10 is configured so that, when the aerial image forming devices 10a, 10b are observed from the observation point, the light diffusion control unit 2 simultaneously satisfies the following two conditions: (Condition 1) Of the light that is irradiated from any one point on the display unit 1 and reaches the observation point, the haze value is 60% or less for light that is reflected by both of the two layers that make up the retrotransmitting optical element. (Condition 2) Of the light that is irradiated from any one point on the display unit 1 and reaches the observation point, the haze value is 60% or more for light that is reflected by only one of the two layers that make up the retrotransmitting optical element.

[0142] By satisfying the above conditions, the aerial image forming devices 10a and 10b according to this embodiment can easily suppress the occurrence of ghost images or ambient light, and can easily display brighter aerial images.

[0143] Here, "reflection occurs in both layers" or "reflection occurs in only one of the two layers" does not refer to physical reflection, but rather to reflection in the sense of changing the direction of travel. Since parallel mirror surfaces are arranged in each layer of a retrotransmissive optical element, which is made up of two layers stacked together, each layer having multiple reflective surfaces, the direction of travel is changed by an odd number of reflections, but not by an even number of reflections. The phrase "reflection occurs" in the above can be rephrased as "reflection occurs an odd number of times, and the direction of travel is changed."

[0144] 8. Manufacturing Method of Aerial Image Forming Device The manufacturing method of the aerial image forming devices 10 a, 10 b according to the present embodiment is not particularly limited. For example, after preparing the display unit 1, the light diffusion control unit 2, the light-transmitting image forming unit 3, and the adhesive layer 4, the display unit 1 is placed at a predetermined position on the housing, and a laminate of the light diffusion control unit 2, the light-transmitting image forming unit 3, and the adhesive layer 4 is placed, thereby obtaining the aerial image forming devices 10 a, 10 b.

[0145] 9. How to Use the Aerial Image Forming Device The aerial image forming devices 10a and 10b according to the present embodiment can be used as display devices for displaying any image or video in the air. There are no specific limitations on how they can be used, and they can be used in the same way as conventionally known display devices.

[0146] [Laminate] The laminate according to this embodiment is the aerial image forming device 10 a, 10 b described above, with the display unit 1 omitted. That is, the laminate according to this embodiment includes a translucent imaging unit 3 that causes light incident from one surface to form an image at a position on the other surface, a light diffusion control unit 2 laminated on one surface of the translucent imaging unit 3, and an adhesion layer 4 laminated between the translucent imaging unit 3 and the light diffusion control unit 2 to adhere the translucent imaging unit 3 to the light diffusion control unit 2. Details of the compositions, structures, etc. of the translucent imaging unit 3, the light diffusion control unit 2, and the adhesion layer 4 are as described above.

[0147] The laminate according to this embodiment can be obtained by preparing the light diffusion control unit 2, the light-transmitting image forming unit 3, and the adhesive layer 4 and then laminating them together. The laminate according to this embodiment can also be used to form the aerial image forming devices 10a and 10b according to this embodiment. That is, the aerial image forming devices 10a and 10b according to this embodiment can be obtained by placing the display unit 1 at a predetermined position on the laminate according to this embodiment.

[0148] In this specification, when it is stated that "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also means "preferably greater than X" or "preferably smaller than Y". Furthermore, when it is stated that "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is stated that "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified.

[0149] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0150] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0151] Example 1 1. Preparation of a composition for light diffusion controlling portion 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 as a high refractive index component and 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator were added to 40 parts by mass (solid content equivalent value; the same applies hereinafter) of polyether urethane methacrylate having a weight average molecular weight of 9,900 obtained by reacting polypropylene glycol, isophorone diisocyanate, and 2-hydroxyethyl methacrylate as a low refractive index component, and then the mixture was heated and mixed at 80°C to obtain a composition for light diffusion controlling portion.

[0152] The weight average molecular weight (Mw) is a weight average molecular weight calculated as standard polystyrene, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> Measurement device: HLC-8320, manufactured by Tosoh Corporation GPC columns (passed in the following order): TSK gel super H-H, TSK gel super HM-H, TSK gel super H2000, manufactured by Tosoh Corporation Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[0153] 2. Formation of Light Diffusion Control Part The obtained composition for light diffusion control part was applied to a polyethylene terephthalate film sheet (thickness: 50 μm) as a process sheet A to form a coating film. This resulted in a laminate consisting of the coating film and the process sheet A.

[0154] Next, the obtained laminate was placed on a conveyor. At this time, the surface of the coating film on the laminate was facing upward, and the longitudinal direction of the process sheet A was parallel to the flow direction of the conveyor. Then, an ultraviolet irradiation device (manufactured by iGraphics, product name "ECS-4011GX") equipped with a linear high-pressure mercury lamp and a cold mirror for focusing was installed relative to the conveyor on which the laminate was placed. This device can irradiate a single point of interest with scattered ultraviolet light in a band shape (almost linear). Note that when installing the device, the ultraviolet irradiation device was installed so that the longitudinal direction of the high-pressure mercury lamp and the flow direction of the conveyor were perpendicular to each other.

[0155] Furthermore, when viewed from the longitudinal direction of the high-pressure mercury lamp, the irradiation angle of the ultraviolet light irradiated from the high-pressure mercury lamp to the laminate was set to -5° with respect to the normal to the laminate surface. Note that the irradiation angle here refers to the acute angle formed by the normal to the laminate surface and the ultraviolet light, expressed as a plus sign, when the ultraviolet light is irradiated toward the downstream side of the conveyor flow, with respect to the position directly below the high-pressure mercury lamp on the laminate, and the acute angle formed by the normal to the laminate surface and the ultraviolet light, expressed as a minus sign, when the ultraviolet light is irradiated toward the upstream side of the conveyor flow.

[0156] Thereafter, the conveyor was operated to move the laminate at a speed of 1.0 m / min, while applying a peak irradiance of 2.5 mW / cm2 to the coating surface. ２ , cumulative light intensity 40.0 mJ / cm ２ The coating film in the laminate was cured by irradiating it with ultraviolet light under the conditions (this curing is sometimes referred to as "primary curing" for convenience).

[0157] Next, a polyethylene terephthalate film sheet (thickness: 38 μm) serving as process sheet B was laminated on the surface of the laminate facing the coating film, thereby obtaining a laminate consisting of process sheet A, the coating film, and process sheet B laminated in this order.

[0158] Then, while moving at a speed of 1.0 m / min, a peak irradiance of 190 mW / cm was applied to the coating film via the process sheet B. ２ , cumulative light intensity 180 mJ / cm ２ The coating film in the laminate was cured by irradiating it with ultraviolet light (scattered light) under the conditions (this curing is sometimes referred to as "secondary curing" for convenience). The peak irradiance and integrated light quantity mentioned above were measured by placing a UV meter (manufactured by Eye Graphics, product name "Eye Ultraviolet Integrated Illuminance Meter UVPF-A1") equipped with a light receiver at the position of the coating film.

[0159] The coating film was sufficiently cured by the above primary curing and secondary curing, and the light diffusion control portion was formed. As a result, a laminate was obtained in which the process sheet A, the light diffusion control portion having a thickness of 200 μm, and the process sheet B were laminated in this order.

[0160] Furthermore, when the cross section of the formed light diffusion control section was observed using a microscope, it was confirmed that a louver structure was formed inside the light diffusion control section, in which a plurality of plate-like regions 201 were arranged in parallel at predetermined intervals, as shown in Fig. 3. The acute angle formed between the main surface of the louver structure and the normal to the light diffusion control section was 3.3°.

[0161] 3. Formation of Pressure-Sensitive Adhesive Layer 65 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate, 5 parts by mass of N-acryloylmorpholine, and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer was measured by the method described above and was found to be 500,000.

[0162] 100 parts by mass of the obtained (meth)acrylic acid ester polymer, 0.6 parts by mass of an epoxy-based curing agent (manufactured by Soken Chemical & Engineering Co., Ltd., product name "E-AX") as a crosslinking agent, and 4 parts by mass of a triazine-based ultraviolet absorber (manufactured by BASF Japan Ltd., product name "Tinuvin 477") as an ultraviolet absorber were mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of a pressure-sensitive adhesive composition.

[0163] The obtained coating solution was applied using a knife coater to the release-treated surface of a heavy-release type release sheet C (thickness: 38 μm), one side of which had been treated with a silicone-based release agent for release, and then dried by heating in a drying oven at 90°C for 1 minute to obtain a coating layer with a thickness of 13 μm.

[0164] Next, the release-treated surface of a light-release type release sheet D (thickness: 38 μm), which was a polyethylene terephthalate film with one side treated with a silicone-based release agent, was attached to the surface of the coating layer opposite to the release sheet C. Thereafter, the coating layer was cured for 7 days under conditions of 23° C. and 50% RH, thereby forming the coating layer into a pressure-sensitive adhesive layer serving as an adhesive layer.

[0165] As a result of the above, a laminate was obtained in which release sheet C, a 13 μm thick pressure-sensitive adhesive layer, and release sheet D were laminated in this order.

[0166] The calculated amount of acidic groups present in the pressure-sensitive adhesive layer relative to all the components constituting the pressure-sensitive adhesive layer was 0 mmol / g, and the calculated amount of hydroxyl groups present in the pressure-sensitive adhesive layer relative to all the components constituting the pressure-sensitive adhesive layer was 1.29 mmol / g.

[0167] Furthermore, the hydroxyl value of the components constituting the pressure-sensitive adhesive layer was calculated to be 72.48 mgKOH / g, and the acid value of the components constituting the pressure-sensitive adhesive layer was calculated to be 0 mgKOH / g.

[0168] 4. Preparation of Laminate The process sheet B was peeled off from the laminate obtained in the above step (2) to expose the light diffusion control part. Subsequently, the release sheet D was peeled off from the laminate obtained in the above step (3), and the exposed surface of the pressure-sensitive adhesive layer was bonded to the exposed surface of the light diffusion control part.

[0169] Furthermore, the release sheet C was peeled off, and the exposed surface of the adhesive layer was laminated to one side of a retrotransmitting optical element (manufactured by Asukanet Co., Ltd., product name "ASKA3D-200NT", length 200 mm x width 200 mm x thickness 6.3 mm) consisting of two layers with multiple reflective surfaces, which served as a light-transmitting imaging section.

[0170] This produced a laminate in which the process sheet, the light diffusion control section, the adhesive layer (adhesive layer), and the light-transmitting image forming section (retrotransmitting optical element) were laminated in this order.

[0171] Example 2 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer was measured by the method described above and was found to be 700,000.

[0172] 100 parts by mass of the obtained (meth)acrylic acid ester polymer, 0.25 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101E") as a crosslinking agent, and 0.1 parts by mass of 3-glycidoxypropylmethyldiethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of a pressure-sensitive adhesive composition.

[0173] A laminate was obtained in the same manner as in Example 1, except that the coating solution of the obtained adhesive composition was used, in which a process sheet, a light diffusion control section, an adhesion layer (adhesive layer), and a light-transmitting imaging section (retrotransmitting optical element) were stacked in that order.

[0174] The calculated amount of acidic groups present in the adhesive layer (pressure-sensitive adhesive layer) relative to the total components constituting the adhesive layer was 0 mmol / g, and the calculated amount of hydroxyl groups present in the adhesive layer relative to the total components constituting the adhesive layer was 1.72 mmol / g.

[0175] The calculated hydroxyl value of the component constituting the adhesive layer was 96.64 mgKOH / g, and the calculated acid value of the component constituting the adhesive layer was 0 mgKOH / g.

[0176] Comparative Example 1: 67.2 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of methyl methacrylate, 8 parts by mass of methacrylic acid, 18 parts by mass of vinyl acetate, 0.4 parts by mass of acrylic acid, and 1.4 parts by mass of 4-hydroxybutyl acrylate were copolymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer was measured by the method described above and was found to be 820,000.

[0177] 100 parts by mass of the obtained (meth)acrylic acid ester polymer, 0.5 parts by mass of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate HX") as a crosslinking agent, and 7.7 parts by mass of a triazine-based ultraviolet absorber (manufactured by BASF Japan, product name "Tinuvin 477") as an ultraviolet absorber were mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of a pressure-sensitive adhesive composition.

[0178] A laminate was obtained in the same manner as in Example 1, except that the coating solution of the obtained adhesive composition was used, in which a process sheet, a light diffusion control section, an adhesion layer (adhesive layer), and a light-transmitting imaging section (retrotransmitting optical element) were stacked in that order.

[0179] The calculated amount of acidic groups present in the adhesive layer (pressure-sensitive adhesive layer) relative to all the components constituting the adhesive layer was 0.055 mmol / g, and the calculated amount of hydroxyl groups present in the adhesive layer relative to all the components constituting the adhesive layer was 0.15 mmol / g.

[0180] The hydroxyl value of the component constituting the adhesive layer was calculated to be 8.56 mgKOH / g, and the acid value of the component constituting the adhesive layer was calculated to be 3.11 mgKOH / g.

[0181] [Test Example 1] (Measurement of total light transmittance of adhesive layer) The adhesive layers (pressure-sensitive adhesive layers) prepared in the examples and comparative examples were measured for total light transmittance (%) using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH7000") in accordance with JIS K7361-1:1997 and ASTM D 1003. The results are shown in Table 1.

[0182]

[0183] [Test Example 2] (Durability Test) The laminates (laminates formed by sequentially stacking a process sheet, a light diffusion control section, an adhesive layer (adhesive layer), and a light-transmitting image forming section (retrotransmitting optical element)) prepared in the examples and comparative examples were stored under dry conditions at 80°C for 500 hours (80°C dry test). After that, they were removed from the laminates and placed in an environment of 23°C and 50% RH. Photographs of each laminate were taken, and the presence of bubbles between the light diffusion control section and the adhesive layer, and between the adhesive layer and the light-transmitting image forming section (retrotransmitting optical element) was visually confirmed. The photographed images are shown in Figure 5. Two laminates were tested for each example.

[0184] As a result, a small number of bubbles were observed in the laminate according to Example 1 (FIG. 5(a)), and no bubbles were observed in the laminate according to Example 2 (FIG. 5(b)). In contrast, a large number of bubbles were observed in the laminate according to Comparative Example 1 (FIG. 5(c)).

[0185] Separately prepared laminates were stored under humid heat conditions of 60°C and 90% RH for 500 hours (60°C 90% RH test). Afterwards, they were removed to an environment of 23°C and 50% RH, and each laminate was photographed and checked for bubbles in the same manner as above. The photographed images are shown in Figure 6. Two laminates were tested for each example.

[0186] As a result, no bubbles were observed in the laminates of Example 1 (FIG. 6(a)) and Example 2 (FIG. 6(b)). In contrast, a large amount of foaming was observed in the laminate of Comparative Example 1 (FIG. 6(c)). Note that, although FIG. 6(b) shows that a small number of small bubbles were generated, these were caused by foreign matter mixed in during the formation of the laminate, and were not caused by the 60°C 90% RH test.

[0187] Furthermore, for the laminates according to Examples 1 and 2 that had undergone the 80° C. dry test, the edges were visually inspected and the positions of the edges were photographed. The photographed images are shown in FIG. 7.

[0188] As a result, slight lifting and peeling was observed at the edges of Example 1 (FIG. 7(a)), whereas no lifting or peeling was observed in the laminate of Example 2 (FIG. 7(b)).

[0189] The aerial image forming device of the present invention can be suitably used as a display or the like that displays an aerial image.

[0190] REFERENCE SIGNS LIST 10a, 10b... aerial image forming device 1... display section 2... light diffusion control section 201... plate-shaped region 202... region with relatively low refractive index 3... light-transmitting image forming section 4... adhesive layer 5... aerial image observation surface 6... observation point

Claims

1. A display unit having a display surface and emitting light from the display surface; a light-transmitting image forming unit arranged on the display surface side of the display unit; a light diffusion control unit laminated on the side of the light-transmitting image forming unit opposite the display unit or on the side of the light-transmitting image forming unit facing the display unit; and an adhesive layer laminated between the light-transmitting image forming unit and the light diffusion control unit and adhesively bonding the light-transmitting image forming unit and the light diffusion control unit, wherein the light-transmitting image forming unit transmits the light originating from the display surface and forms an image at a position on the side opposite the display unit; the light diffusion control unit diffuses or transmits light incident into the light diffusion control unit depending on the angle of incidence, and has a louver-like regular internal structure with a plurality of plate-like regions with a relatively high refractive index within a region with a relatively low refractive index; the adhesive layer is composed of one of a pressure-sensitive adhesive, an adhesive, and a pressure-sensitive adhesive, and the amount of acidic groups present in the adhesive layer relative to the total components constituting the adhesive layer is 0.050 mmol / g or less. An aerial image forming device characterized by:

2. An aerial image forming device according to claim 1, characterized in that the amount of hydroxy groups present in the adhesive layer relative to the total components constituting the adhesive layer is 0.2 mmol / g or more and 20.0 mol / g or less.

3. The aerial image forming device according to claim 1, characterized in that the hydroxyl value of the components constituting the adhesion layer is 10 mgKOH / g or more and 500 mgKOH / g or less, and the acid value of the components constituting the adhesion layer is 0 mgKOH / g or more and 3.0 mgKOH / g or less.

4. The aerial image forming device according to claim 1, wherein the total light transmittance of said adhesive layer is 80% or more.

5. The aerial image forming device described in claim 1, characterized in that the display unit is positioned relative to the light diffusion control unit and the light-transmitting image forming unit so that the display surface and the surface of the light diffusion control unit opposite the light-transmitting image forming unit are non-parallel.

6. The aerial image forming device described in claim 1, characterized in that, when a direction perpendicular to the longitudinal direction of the plate-like region and existing in a plane of the light diffusion control unit opposite the light-transmitting image forming unit is defined as a first direction, each of the plate-like regions is inclined toward the first direction within the light diffusion control unit.

7. The aerial image forming device according to claim 1, wherein the light-transmitting imaging unit is provided with a retrotransmitting optical element that retrotransmits incident light.

8. The aerial image forming device described in claim 7, characterized in that the retrotransmissive optical element is formed by stacking two layers each having a plurality of reflective surfaces, and in each of the two layers, the plurality of reflective surfaces are arranged perpendicular to one side of the retrotransmissive optical element and at a predetermined distance from each other, and the two layers are stacked so that the reflective surface in one layer is perpendicular to the reflective surface in the other layer.

9. A laminate comprising: a translucent imaging section that images light incident from one surface at a position on the other surface; a light diffusion control section laminated on one surface of the translucent imaging section; and an adhesive layer laminated between the translucent imaging section and the light diffusion control section and adhesively connecting the translucent imaging section and the light diffusion control section, wherein the light diffusion control section diffuses or transmits light incident into the light diffusion control section depending on the angle of incidence, and has a louver-like regular internal structure with a plurality of plate-like regions with a relatively high refractive index within a region with a relatively low refractive index, and the adhesive layer is composed of one of a pressure-sensitive adhesive, an adhesive, and a pressure-sensitive adhesive, and the amount of acidic groups present in the adhesive layer relative to the total components constituting the adhesive layer is 0.050 mmol / g or less.

Images