WO2021251131A1

WO2021251131A1 - Transparent screen for water tank, water tank, and transparent image display system

Info

Publication number: WO2021251131A1
Application number: PCT/JP2021/019832
Authority: WO
Inventors: 俊太郎伊吹; 誠加茂
Original assignee: 富士フイルム株式会社
Priority date: 2020-06-08
Filing date: 2021-05-25
Publication date: 2021-12-16
Also published as: CN115917427A; JPWO2021251131A1; JP7449384B2

Abstract

The present invention addresses the problem of providing: a transparent screen, for a water tank, which can be used without any problems, even during extended use, in an acrylic plate for a water tank; a water tank having this transparent screen for a water tank; and a transparent image display system that uses said water tank. The present invention solves the abovementioned problem by using a transparent screen, for a water tank, that has an adhesive layer, a transparent supporting body, and a light reflecting layer in that order, wherein the total light transmittance is 70% or more, and the adhesive layer has an initial adhesive force of 3.0 N/25 mm or more and an adhesive strength over time of 4.0 to 20.0 N/25 mm after four days have passed under conditions of 85°C and 10% RH.

Description

Aquarium transparent screen, aquarium, and transparent image display system

The present invention is a transparent screen for an aquarium that displays the projected light projected from a projector visually as a projected image to an observer by being attached to the aquarium, and a water tank to which the transparent screen for the aquarium is attached. And a transparent image display system using this water tank.

In recent years, transparent screens that project and display information such as advertisements on show windows and information boards of commercial buildings in the city while maintaining light transmission have been attracting attention in the field of buildings.
In addition to the building field, the use of transparent screens as displays for projecting location information on the windshield of automobiles has been actively studied in recent years, and is attracting attention in the automobile field as well.

In particular, an article containing a transparent screen in which a light scattering substance is dispersed in a transparent dispersion medium and a window substrate such as a glass window substrate has attracted attention from the viewpoint of screen transparency and image sharpness. There is. As an example of studying a transparent screen, a resin film in which fine particles such as diamond and silica are dispersed, as in Patent Document 1, Patent Document 2, and Patent Document 3, is known.

Japanese Unexamined Patent Publication No. 2016-177245 Republished WO2008-016088 Japanese Unexamined Patent Publication No. 2011-113068

In the fields of buildings and automobiles, the window base material is firmly fixed to the installation site and cannot be easily separated or dismantled.
On the other hand, the screen film is often attached to the window substrate later as needed. In addition, if it becomes unnecessary or is desired to be replaced due to stains on the screen film, it is desirable to promptly remove the screen film and return the window base material to the same state as before the installation of the screen film. ..

By the way, in the past, glass was often used as the window base material. However, a resin window base material may be used with an emphasis on weight reduction, degree of freedom in shape, and toughness. As a material that can withstand long-term use and has sufficient transparency, for example, a window base material made of acrylic resin has been proposed.

Among the acrylic resin window base materials, the problems when the transparent screen is attached to the acrylic plate for the aquarium in the aquarium are high transmittance and no foam generation during the period of use. .. It should be noted that the generation of bubbles means that air invades between the transparent screen and the acrylic plate for the aquarium during the period of use, resulting in a state in which bubbles are generated.
It is also conceivable to remove the screen for long-term use of the transparent screen for screen replacement and screen removal. Here, in the conventional transparent screen, when the transparent screen is peeled off, the transparent screen itself is peeled off, but there is a problem of so-called adhesive residue, in which only the adhesive remains on the acrylic plate for the aquarium.
Aquarium acrylic plates are very expensive because they require high transmittance so that fish schools can be viewed from inside the room, and they are stacked in a thickness of several tens of centimeters to withstand tens of tons of water pressure. Therefore, once installed, the aquarium itself will not be replaced. Therefore, the transparent screen used for the water tank is required to solve this problem of adhesive residue.

As a result of diligent studies using various adhesives on the aquarium acrylic plate, it is possible to suppress the generation of bubbles, and it is possible to peel off, so that the adhesive does not remain on the aquarium acrylic plate when peeled off. It was found that the adhesive layer of the transparent screen for use requires the following performance.
That is, in order to achieve the above object, (1) the initial adhesive strength is 3.0 N / 25 mm or more, and (2) the increase in the adhesive strength after aging is suppressed, and the adhesive strength after aging is 4. It was found that it was necessary to have a range of 0.0 to 20.0 N / 25 mm. If these requirements are met, a transparent screen for an aquarium that can be used as an acrylic plate for an aquarium can be obtained.
The adhesive layer of the transparent screen for a water tank has (3) an initial adhesive force of 10 N / 25 mm or less, and (4) a storage elastic modulus of the adhesive layer of 1.0 × 10 ⁵ to 1.0 × 10 ⁸ Pa. It was also found that (5) the internal haze is preferably less than 0.8% in order to obtain high visibility.

That is, in order to achieve the above problems, the present invention has the following configurations.
[1] A transparent screen for an aquarium having an adhesive layer, a transparent support, and a light reflecting layer in this order.
The total light transmittance is 70% or more,
The adhesive layer has an initial adhesive strength of 3.0 N / 25 mm or more, and has an adhesive strength over time of 4.0 to 20 after 4 days have passed under the conditions of a temperature of 85 ° C. and a humidity of 10% RH. It is 0N / 25mm,
A transparent screen for aquariums that is attached to an acrylic plate for aquariums via an adhesive layer and reflects the projected light projected from the projector to display the image on the projection side.
[2] The transparent screen for an aquarium according to [1], wherein the initial adhesive strength of the adhesive layer is 10 N / 25 mm or less.
[3] The transparent screen for an aquarium according to [1] or [2], wherein the adhesive layer has a storage elastic modulus of 1.0 × 10 ⁵ to 1.0 × 10 ^{8 Pa at 25 ° C.}
[4] Any of [1] to [3], wherein at least one of the light reflecting layers has a cholesteric liquid crystal layer, all the cholesteric liquid crystal layers have the same spiral sense, and the following formula (1) is satisfied. Transparent screen for water tank described in Crab.
R [45,30] (550) / R [45,15] (550) ≧ 1.3 Equation (1)
Here, R [-45, 30] (550) is a polar angle 30 at an azimuth angle 180 ° deviated from the azimuth angle of the incident light with respect to the incident light having a polar angle −45 ° on the transparent screen for a water tank. Represents the reflectance at a wavelength of 550 nm, measured at a light receiving angle of °, where R [45,15] (550) is the incident light with respect to the incident light at a polar angle of −45 ° to the transparent screen for a water tank. It represents the reflectance at a wavelength of 550 nm, which is measured at a light receiving angle of a polar angle of 15 ° at an azimuth angle deviated by 180 ° from the azimuth angle of.
[5] The transparent screen for an aquarium according to any one of [1] to [4], further having a protective film on the side opposite to the transparent support of the adhesive layer.
[6] A water tank in which the transparent screen for water tank according to any one of [1] to [5] is attached to the surface of the water tank made of an acrylic plate for water tank by an adhesive layer.
[7] A transparent image display system that projects projected light from the viewing side onto the water tank according to [6], superimposes the projected light on the water tank, and displays an image generated by the projected light of the projector.

According to the present invention, there is provided a transparent screen for an aquarium that can be used for an acrylic plate for an aquarium without any problem even if it is used for a long period of time, a water tank having the transparent screen for the water tank, and a transparent image display system using the water tank. ..

FIG. 1 is a configuration diagram of a transparent screen for an aquarium having a cholesteric reflective layer. FIG. 2 is a configuration diagram of a transparent screen for an aquarium having an optical shape layer and a light reflection layer. FIG. 3 is a configuration diagram of a transparent screen for an aquarium having a light reflecting layer.

Hereinafter, the transparent screen for a water tank, the water tank, and the transparent image display system of the present invention will be described in detail.
The description of the constituent elements described below may be based on the representative embodiments of the present invention, but the present invention is not limited to such embodiments.

The transparent screen for an aquarium of the present invention has an adhesive layer, a transparent support, and a light reflecting layer in this order. The transparent screen for aquarium of the present invention is attached (attached) to the aquarium by attaching the adhesive layer to the aquarium acrylic plate (acrylic resin for the aquarium, acrylic base material for the aquarium) constituting the aquarium. ..
Such a transparent screen for an aquarium of the present invention reflects the projected light projected from the projector so that, for example, a visitor to the aquarium observes the inside of the aquarium and the image from the projector in an superimposed state. It makes it possible.

As described above, the transparent screen for aquarium of the present invention is attached to the acrylic plate for aquarium forming the aquarium by an adhesive layer.
The acrylic plate for aquarium to which the transparent screen for aquarium of the present invention is attached is carefully removed from dirt on the surface before being laminated with the transparent screen for aquarium in order to ensure adhesion with the transparent screen for aquarium. It is preferable to keep it.

The aquarium acrylic plate is usually used in a rectangular shape, but other shapes such as a circle, an ellipse, and a triangle may be used.

The size of the acrylic plate for the aquarium is appropriately determined according to the purpose of the aquarium. Further, the thickness is usually set to, for example, the strength required in the mode in which it is used, depending on the application.

[Light reflection layer]
As the light reflecting layer, a known layer can be widely used as long as the projected light projected from the projector can be visually recognized as an image by an observer.
As a preferable example, a transparent layer in which a light scatterer is dispersed in a transparent dispersion medium is exemplified.
Examples of transparent dispersion media include organic polymers and inorganic oxide polymers.
Examples of the organic polymer include polyester resin, polycarbonate resin, polyacrylic resin, polystyrene resin, polyarylate resin, polyolefin resin, polyvinyl chloride resin, polyvinylidene chloride resin, polysulfone resin, polyethersulfone resin, diacetylcellulose resin, and the like. Examples thereof include triacetyl cellulose resin, ethylene vinyl alcohol copolymer, polyvinyl alcohol resin, polyvinyl butyral resin and the like.
Further, the inorganic oxide polymer is an inorganic oxide polymerized in a network shape through oxygen atoms centering on atoms such as silicon, titanium, zirconium, iron, zinc, tin, hafnium, and tungsten. It is a polymer. Examples of the inorganic oxide polymer include those using silicon oxide such as silica, alumina, titania, zirconia, iron oxide, zinc oxide, tin oxide, hafnium oxide, tungsten oxide and the like as raw materials or starting materials. can. Further, these can be mixed and used.

Examples of light scatterers include low refractive index particles such as hollow silica beads and hollow resin beads, and high refractive index particles such as titanium oxide, zirconium oxide, iron oxide, tin oxide, barium titanate and diamond. Be done.
Among these, titanium oxide particles, zirconium oxide particles, and diamond particles are preferably exemplified. Since these particles have a high refractive index and a strong light scattering property, they are preferable in that they can achieve both transparency and sharpness of an image when used as a light scattering body for a transparent screen for a water tank.

Further, as another preferable light-reflecting layer, a light-reflecting layer in which light-reflecting fine particles are dispersed can also be used.
As an example, the light reflecting layer described in paragraphs [0033] to [0045] of International Publication No. 2017/94550 is exemplified. This light-reflecting layer contains a transparent binder and light-reflecting fine particles.
In this light-reflecting layer, light-reflecting fine particles dispersed in a transparent binder are aggregated in an appropriate size, and while maintaining transparency, the projected light projected from the projector is diffusely scattered and reflected. It can be projected. When this light-reflecting layer is used as the light-reflecting layer of a transparent screen for a water tank, the transparency and color reproducibility are excellent, the brightness is high, and the image can be clearly seen.

In the transparent screen for a water tank of the present invention, a particularly preferable example of the light reflecting layer is a light reflecting layer having a cholesteric liquid crystal layer. The cholesteric liquid crystal layer is, in other words, a layer containing a cholesteric liquid crystal structure. The cholesteric liquid crystal layer is a layer formed by fixing a cholesteric liquid crystal phase in which a liquid crystal compound is cholesterically oriented.
A transparent screen having a cholesteric liquid crystal layer and the like are described in detail in, for example, Japanese Patent Application Laid-Open No. 2018-400569, but the parts particularly necessary for a transparent screen for an aquarium are supplemented below.

FIG. 1 conceptually shows an example of a transparent screen for an aquarium of the present invention having a cholesteric liquid crystal layer as a light reflecting layer.
The transparent screen for aquarium shown in FIG. 1 has a first adhesive layer 6, a first transparent support 5, a second adhesive layer 4, a second transparent support 3, an alignment layer 2, and a light reflecting layer from the bottom of the figure. Has 1. The light reflecting layer 1 has a cholesteric liquid crystal layer.
In the transparent screen for a water tank shown in FIG. 1, the first adhesive layer 6 is an adhesive layer in the transparent screen for a water tank of the present invention, and the first transparent support 5 is a transparent support in the transparent screen for a water tank of the present invention. Is. Therefore, in the transparent screen for aquarium shown in FIG. 1, the projected light (image light, projected light) from the projector is projected from the light reflecting layer 1 side.
Further, although not shown in FIG. 1, a transparent screen for an aquarium of the present invention may be produced by using a peelable support.
For example, an alignment layer 2 is formed on the surface of the second transparent support 3, and a reflection layer laminate in which a light reflection layer 1, that is, a cholesteric liquid crystal layer is formed on the surface of the alignment layer 2, is produced, and the light of the reflection layer laminate is produced. A releasable support is attached to the reflective layer 1. On the other hand, an adhesive sheet is produced in which the first adhesive layer 6 is formed on one surface of the first transparent support 5 and the second adhesive layer 4 is formed on the other surface. Preferably, an easily peelable protective film is attached to the adhesive layer of the adhesive sheet.

In the transparent screen for a water tank of the present invention, when the light reflecting layer 1 has a cholesteric liquid crystal layer, a retardation layer or a retardation layer or, as needed, like a known light reflecting member having a cholesteric liquid crystal layer. It may have a retardation layer and a linear modulator.
The retardation layer is arranged on the incident side of the projected light with respect to the cholesteric liquid crystal layer, and the linear polarizing element is arranged on the incident side of the projected light with respect to the retardation layer.
As the retardation layer and the linear polarizing element, various known ones can be used.

In the transparent screen for aquarium shown in FIG. 1, the light reflecting layer 1 (cholesteric liquid crystal layer) is formed on the second transparent support 3 and the alignment layer 2.
The second transparent support 3 supports the alignment layer 2 and the light reflection layer 1. The second transparent support 3 is not limited and is transparent as long as it is used in a known light-transmitting optical member having a cholesteric liquid crystal layer, such as various resin films, as long as it has sufficient light-transmitting property. Various supports are available.
The alignment layer 2 is for orienting the liquid crystal compound forming the cholesteric liquid crystal layer to be the light reflection layer 1. The alignment layer 2 is also not limited, and various known alignment layers (alignment films) used in known light-transmitting optical members having a cholesteric liquid crystal layer such as a rubbing-treated resin film can be used. It is possible.

As an example, the transparent screen for a water tank shown in FIG. 1 is a laminated body in which an alignment layer 2 is formed on the surface of a second transparent support 3 and a light reflection layer 1 is formed on the surface of the alignment layer 2, as described above. This laminated body is produced by laminating the laminated body with the second transparent support 3 side as the second adhesive layer 4 side.
The second adhesive layer 4 is not limited, and is a known light-transmitting optical member such as an adhesive used for a commercially available double-sided adhesive sheet and a transparent optical adhesive (OCA (Optical Clear Adhesive)). Various known pressure-sensitive adhesives used in the above can be used.
The pressure-sensitive adhesive suitable for the second pressure-sensitive adhesive layer 4 will be described in detail later. Further, in the transparent screen for aquarium shown in FIG. 1, a double-sided adhesive sheet having adhesive layers on both sides of the resin film can also be used. This point will be described in detail later.

In the transparent screen for aquarium of the present invention, the alignment layer 2 and the second transparent support 3 are not essential constituent requirements. That is, the transparent screen for an aquarium of the present invention may have a configuration in which the light reflecting layer 1 is directly bonded to the second adhesive layer 4. Further, the transparent screen for a water tank of the present invention may have a structure in which a laminated body of an alignment layer 2 and a light reflection layer 1 is bonded to a second adhesive layer 4. Further, in the transparent screen for aquarium of the present invention, the second adhesive layer 4 is not an indispensable constituent requirement.
In this configuration, as an example, in the method using the above-mentioned peelable support, a laminated body having the second transparent support 3, the alignment layer 2 and the light reflecting layer 1 formed is produced, and the peelable support is provided on the light reflecting layer 1. After the bodies are bonded together, the second transparent support 3 or the alignment layer 2 may be peeled off and then bonded to the second adhesive layer 4.
That is, the transparent screen for an aquarium of the present invention may have a configuration in which the light reflecting layer 1 is directly formed on the first transparent support 5, as shown in FIG. 3 described later.

[Cholesteric liquid crystal layer]
In the transparent screen for an aquarium, the light reflecting layer may include one or more cholesteric liquid crystal layers.
Other layers such as an alignment layer and an adhesive layer may be included between the two or more cholesteric liquid crystal layers. Further, another layer such as a base layer and a transparent layer may be included between the cholesteric liquid crystal layer and the retardation layer.

(Cholesteric liquid crystal structure)
The cholesteric liquid crystal structure may be any structure as long as the orientation of the liquid crystal compound (cholesteric liquid crystal orientation) which is the cholesteric liquid crystal phase is maintained. The cholesteric liquid crystal layer typically has a structure in which a polymerizable liquid crystal compound is placed in an oriented state of the cholesteric liquid crystal phase, and then polymerized and cured by irradiation with ultraviolet rays, heating, etc. to have no fluidity, and at the same time. In addition, the structure may be such that the orientation state does not change due to an external field, an external force, or the like.
In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained, and the liquid crystal compound does not have to exhibit liquid crystal properties anymore. For example, the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and no longer have liquid crystallinity.

The cholesteric liquid crystal phase is known to exhibit circularly polarized light selective reflection that selectively reflects the circularly polarized light of either the right-handed circularly polarized light or the left-handed circularly polarized light and transmits the circularly polarized light of the other sense. In the present specification, the circularly polarized light selective reflection may be simply referred to as a selective reflection.
As a film containing a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized light selective reflectivity is fixed, many films formed from a composition containing a polymerizable liquid crystal compound have been known conventionally, and the cholesteric liquid crystal layer has been conventionally known. You can refer to the technology.

The center wavelength λ of the selective reflection of the cholesteric liquid crystal layer depends on the pitch P (= period of the spiral) of the spiral structure in the cholesteric liquid crystal phase, and follows the relationship between the average refractive index n and λ = n × P of the cholesteric liquid crystal structure.
In the present specification, the central wavelength λ of the selective reflection of the cholesteric liquid crystal layer means the wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer.

As can be seen from the above-mentioned relationship of λ = n × P, the center wavelength λ of the selective reflection of the cholesteric liquid crystal layer can be adjusted by adjusting the pitch (spiral pitch) of the spiral structure. It is preferable that the cholesteric liquid crystal layer exhibiting selective reflection in the visible light region also has a central wavelength of selective reflection in the visible light region. For example, adjusting the values of n and / or P to selectively reflect either right-handed or left-handed circularly polarized light in response to either red light, green light, or blue light. The center wavelength λ can be adjusted.

The transparent screen for a water tank of the present invention does not generate a clear double image as in the display of a projected image using a virtual image, but diffuse reflection occurs when the light reflected on the surface of the water tank re-enters the transparent screen. As a result, image blurring occurs and the sharpness is reduced.
Therefore, when the transparent screen for aquarium of the present invention is used by being bonded to the surface of the aquarium acrylic plate, the image blur caused by the reflected light reflected on the front surface or the back surface of the aquarium acrylic plate is reduced. , It is preferable to attach the light to the aquarium acrylic plate so that the light is obliquely incident on the cholesteric liquid crystal layer (light reflecting layer). Alternatively, it is preferable to set the projection direction of the projected light from the projector so that the light is obliquely incident on the cholesteric liquid crystal layer.
Further, when the light is obliquely incident on the cholesteric liquid crystal layer in this way, the center wavelength of the selective reflection is shifted to the short wavelength side by the so-called blue shift. Therefore, for the wavelength of selective reflection required for displaying the projected image, n × P is adjusted so that λ calculated according to the above equation of λ = n × P is on the long wavelength side. Is preferable.
In the cholesteric liquid crystal layer having a refractive index n _2, when the central wavelength of the selective reflection when a ray relative to the normal direction of the cholesteric liquid crystal layer passes at an angle theta ₂ between λ _{_d,} λ _d to the following formula It is represented by. The normal direction of the cholesteric liquid crystal layer is the spiral axis direction of the cholesteric liquid crystal layer.
λ _d = n ₂ × P × cos θ ₂

For example, it is assumed that the cholesteric liquid crystal layer and the retardation layer A having a λ / 2 phase difference are used as the light reflection layer 1.
At this time, the light incident from the phase difference layer A side having a λ / 2 phase difference at an angle of 45 ° to 70 ° with respect to the normal of the projected image display portion in the air having a refractive index of 1 is usually refracted. The retardation layer A having a coefficient of about 1.45 to 1.80 is transmitted at an angle of 23 ° to 40 ° with respect to the normal of the projected image display portion, and is incident on the cholesteric liquid crystal layer having a refractive index of about 1.61. Since light is transmitted at an angle of 26 ° to 36 ° in the cholesteric liquid crystal layer, this angle and the center wavelength of the desired selective reflection may be inserted into the above equation to adjust n × P.
Since the spiral pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or the concentration thereof added, a desired spiral pitch can be obtained by adjusting these. For the measurement method of spiral sense and pitch, refer to "Introduction to Liquid Crystal Chemistry Experiment", ed. Can be used.

By adjusting the center wavelength λ of the selective reflection of the cholesteric liquid crystal layer to be used according to the emission wavelength range of the light source used for projection and the usage state of the cholesteric liquid crystal layer, the light utilization efficiency is good and clear projection is performed. The image can be displayed.
In particular, when a plurality of cholesteric liquid crystal layers are provided, light is used by adjusting the center wavelength λ of the selective reflection of each cholesteric liquid crystal layer according to the emission wavelength range of the light source used for projection. It is efficient and can display clear color projection images.
Examples of the usage state of the cholesteric liquid crystal layer include the angle of incidence of the projected light on the cholesteric liquid crystal layer (projection direction), the direction of observing the projected image, and the like.

As the cholesteric liquid crystal layer, a cholesteric liquid crystal layer having a spiral sense of either right or left is used. The sense of circularly polarized light reflected by the cholesteric liquid crystal structure matches the sense of the spiral of the cholesteric layer (cholesteric liquid crystal phase).
The spiral senses of the cholesteric liquid crystal layers having different center wavelengths of selective reflection may be the same or may contain different ones, but are preferably the same.

In the cholesteric liquid crystal layer, the full width at half maximum Δλ (nm) of the selective reflection band showing selective reflection depends on the birefringence Δn of the liquid crystal compound and the spiral pitch P described above, and follows the relationship of Δλ = Δn × P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn.
The Δn can be adjusted by adjusting the type and mixing ratio of the polymerizable liquid crystal compound, or by controlling the temperature at the time of fixing the orientation.
The full width at half maximum Δλ of the selective reflection may be any one of 15 to 200 nm, 15 to 150 nm, 20 to 100 nm, and the like.

The cholesteric liquid crystal layer used in the present invention is preferably one in which a liquid crystal compound is fixed in a cholesteric oriented state.
The cholesteric orientation state may include both an orientation state that reflects the right circularly polarized light and an orientation state that reflects the left circularly polarized light. The liquid crystal compound used in the present invention is not particularly limited, and various known ones can be used.

As is well known, the cholesteric liquid crystal layer has a striped pattern of bright and dark parts when the cross section is observed using a scanning electron microscope (SEM).
In the transparent screen for a water tank of the present invention, when the reflective layer has a cholesteric liquid crystal layer, it is preferable that the striped pattern of the cholesteric liquid crystal layer has a wavy structure. The wavy structure preferably has an average value of the distance between peaks of 0.5 to 50 μm. The average value of the inter-peak distances of the wavy structure is more preferably 1.5 to 30 μm, still more preferably 2.5 to 20 μm.
In a normal cholesteric liquid crystal layer, the bright part and the dark part are parallel to the main surface of the cholesteric liquid crystal layer, that is, the forming surface of the cholesteric liquid crystal layer. The main surface is the maximum surface of the layer (film, plate-like material, sheet-like material). Such a normal cholesteric liquid crystal layer mirror-reflects (normally reflects) incident light.
On the other hand, the cholesteric liquid crystal layer having a wavy structure in the bright part and the dark part diffusely reflects (scattered reflection) the incident light. The cholesteric liquid crystal layer, that is, the reflective layer diffusely reflects light, so that the transparent screen for a water tank of the present invention has a clear image with sufficient brightness when observed not only from the front but also from the horizontal and vertical directions. Can be observed.

In the present invention, the wavy structure specifically means that at least one region M in which the absolute value of the inclination angle with respect to the main surface of the cholesteric liquid crystal layer is 5 ° or more in the continuous line of the bright part or the dark part of the striped pattern. It means that there are two peaks or valleys having an inclination angle of 0 ° at the two points closest to each other across the region M.

A mountain or valley with an inclination angle of 0 ° includes convex and concave points, but if the inclination angle is 0 °, it also includes stair-like and shelf-like points. In the wavy structure, it is preferable that a region M in which the absolute value of the inclination angle is 5 ° or more and a plurality of peaks or valleys sandwiching the region M are repeated in the continuous line of the bright part or the dark part of the striped pattern.

The inter-peak distance of the wavy structure is the distance between the peaks of the cholesteric liquid crystal layer in the plane direction of the two closest peaks or valleys with an inclination angle of 0 ° across the region M. The length in the long axis direction of the cross section is 100 μm, and the values are arithmetically averaged over the total film thickness.

Here, if each continuous line touches either of the two interfaces of the film and is interrupted, both ends of the interrupted part are not regarded as peaks or valleys. Further, when each continuous line has a bent structure as shown in FIG. 2 described later, it is considered that the continuous line is interrupted there, and both ends thereof are not regarded as peaks or valleys.

As described above, the transparent screen for an aquarium of the present invention preferably has at least one cholesteric liquid crystal layer as the reflective layer.
In this case, it is preferable that the spiral senses of all the cholesteric liquid crystal layers, that is, the turning directions of the selectively reflected polarized light are the same. Further, it is preferable to satisfy the following formula (1).
R [45,30] (550) / R [45,15] (550) ≧ 1.3 Equation (1)
In this equation (1), R [45,30] (550) is an azimuth angle 180 ° deviated from the azimuth angle of the incident light with respect to the incident light having a polar angle of −45 ° on the transparent screen for a water tank. It represents the reflectance at a wavelength of 550 nm, measured at a light receiving angle of a polar angle of 30 °.
On the other hand, R [-45,15] (550) has a polar angle of 15 ° at an azimuth 180 ° deviated from the azimuth of the incident light with respect to the incident light having a polar angle of −45 ° on the transparent screen for a water tank. It represents the reflectance at a wavelength of 550 nm, which is measured by the light receiving angle of.
That is, in the above equation (1), even if the light is incident at the same polar angle of −45 °, the reflectance when the light is received at the polar angle of 30 ° is 1.3 times the reflectance when the light is received at the polar angle of 15 °. It shows that it is the above.
By satisfying this formula (1), the transparent screen for aquarium of the present invention exhibits good diffuse reflectance. As a result, as described above, it is possible to suitably observe the projected image regardless of the vertical / horizontal direction and the observation direction.

[Adhesive layer]
In the transparent screen for aquarium of the present invention, the adhesive layer (first adhesive layer 6 in FIG. 1) bonded to the acrylic plate for aquarium is
(1) The initial adhesive strength is 3.0 N / 25 mm or more, and
(2) The increase in adhesive strength after aging is suppressed, and the adhesive strength over time, that is, the adhesive strength after 4 days under the conditions of temperature 85 ° C. and humidity 10% RH is 4.0 to 20.0 N / 25 mm. Satisfy that it is a range.
In the transparent screen for aquarium of the present invention, when the adhesive layer satisfies this condition, the generation of bubbles over time is suppressed, and when the adhesive is peeled off from the acrylic plate for aquarium after long-term use, the adhesive is used for the aquarium. It is possible to prevent so-called adhesive residue remaining on the acrylic plate.
Further, in the transparent screen for aquarium, preferably, the adhesive layer is
(3) The initial adhesive strength is 10 N / 25 mm or less.
(4) The storage elastic modulus at 25 ° C. is in the range of ^{1.0 × 10 5} to 1.0 × 10 ^{8 Pa, and}
(5) Satisfy that the internal haze is less than 0.8%.

The material constituting the adhesive layer described above is not particularly limited, but a material that does not interfere with the transparency of the transparent screen for aquarium is preferable.
Examples of the composition capable of forming such a pressure-sensitive adhesive layer include pressure-sensitive adhesive compositions using commonly used materials such as acrylic-based, silicone-based, urethane-based, and rubber-based materials. Among them, an acrylic pressure-sensitive adhesive composition is preferable because of its excellent transparency.

As a preferred example, the pressure-sensitive adhesive composition comprises a cross-linking agent and a polymer having a reactive functional group which is a functional group capable of reacting with the cross-linking agent, and the cross-linking agent and the cross-linking polymer form a cross-linked structure. Examples include those that form an adhesive layer. In the present specification, "a polymer having a reactive functional group which is a functional group capable of reacting with a cross-linking agent" is also referred to as "a cross-linking polymer".

(I) Crosslinkable polymer The crosslinkable polymer is preferably an acrylic polymer having a reduced carboxyl group content from the viewpoint of further reducing the amount of outgas. Specifically, the content of the carboxyl group in the crosslinkable polymer is 1.0 part by mass or less of the structural unit having a carboxyl group with respect to 100 parts by mass of the total amount of the monomers for forming the crosslinkable polymer. It is preferably present, and more preferably 0.5 parts by mass or less. Furthermore, the crosslinkable polymer is preferably an acrylic polymer having no carboxyl group. In the present specification, the "acrylic polymer having no carboxyl group" is also referred to as a "carboxyl group-free polymer".
Similarly, the pressure-sensitive adhesive layer constituting the transparent screen for an aquarium of the present invention preferably has a low content of a carboxyl group, and further preferably does not substantially contain a component having a carboxyl group. Examples of the structural unit having a carboxyl group include acrylic acid, methacrylic acid, and itaconic acid.

The structural unit of the crosslinkable polymer is not particularly limited.
The crosslinkable polymer may be composed of only a structural unit based on an acrylic compound which is one or more compounds of a compound having a (meth) acryloyl group and a derivative thereof (ester, acrylonitrile, etc.). It may contain a structural unit based on an acrylic compound and a structural unit based on a compound other than the acrylic compound.
In addition, "(meth) acryloyl group" in this specification means both acryloyl group and methacryloyl group. The same applies to other similar terms in this regard. Further, the compound other than the above-mentioned acrylic compound may be composed of one kind of compound or may be composed of a plurality of kinds of compounds.

A (meth) acrylic acid ester is mentioned as a preferable example of the above-mentioned acrylic compound.
Specific examples of the (meth) acrylic acid ester include a chain skeleton such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. Has (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) ) (Meta) acrylates having a cyclic skeleton such as acrylates, tetrahydrofurfuryl (meth) acrylates and imide acrylates, 2-hydroxyethyl (meth) acrylates, 2-hydroxypropyl (meth) acrylates, 3-hydroxypropyl (meth) acrylates. , 2-Hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and other (meth) acrylates, N-methylaminoethyl (meth) acrylate and other amino groups. (Meta) acrylate having an epoxy group, and (meth) acrylate having an epoxy group such as glycidyl (meth) acrylate can be mentioned.

Among these, the crosslinkable polymer preferably contains a structural unit based on an alkyl (meth) acrylate having an alkyl group having 4 or less carbon atoms. In the present specification, "alkyl (meth) acrylate having 4 or less carbon atoms of an alkyl group" is also referred to as "lower alkyl compound".
Specific examples of such lower alkyl compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Examples thereof include acrylates, sec-butyl (meth) acrylates, and tert-butyl (meth) acrylates.

Among these, n-butyl (meth) acrylate, methyl (meth) acrylate and the like are selected from the viewpoint of facilitating an appropriate balance between enhancing the adhesive properties of the adhesive layer and reducing the amount of outgas. preferable. The lower alkyl compound may be used alone or in combination of two or more.

Examples of the monomer giving a structural unit based on a compound other than the acrylic compound include olefins such as ethylene and norbornene, carboxylic acid vinyl esters such as vinyl acetate, and aromatic compounds having an ethylenically unsaturated bond such as styrene. In the present specification, "a monomer that gives a structural unit based on a compound other than an acrylic compound" is also referred to as "another polymerizable compound".

The reactive functional group of the crosslinkable polymer is preferably a functional group that reacts with a crosslinking agent described later. Examples of such functional groups other than the carboxyl group include a hydroxyl group, an amino group, and an amide group.

The type of the compound that gives a structural unit having a reactive functional group in the crosslinkable polymer is not particularly limited.
Examples thereof include the above-mentioned (meth) acrylate having a hydroxyl group and the (meth) acrylate having an amino group. Examples of the ethylenically unsaturated compound having such a reactive functional group include an ethylenically unsaturated compound containing an amide group and an alcohol having a vinyl group. In the present specification, the "ethylenically unsaturated compound having a reactive functional group" is also referred to as a "reactive compound".
Specific examples of such reactive compounds include acrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, 5-hexene-1-ol, 5-hexene-3. -All, 4-pentene-1-all and the like can be mentioned.

As the reactive functional group of the reactive compound, a hydroxyl group that is less likely to cause discoloration due to heat or the like is preferable. Therefore, the reactive compound is preferably a (meth) acrylate having a hydroxyl group and / or an alcohol having a vinyl group.

The crosslinkable polymer may contain a structural unit based on a compound having an ethylenically unsaturated bond other than the structural unit based on the above-mentioned lower alkyl compound and the structural unit based on the reactive compound. Specific examples of the monomer giving such a structural unit include olefins, carboxylic acid vinyl esters, aromatics having an ethylenically unsaturated bond, and the like, as in the case of the other polymerizable compounds described above.

When such a crosslinkable polymer contains a structural unit based on a lower alkyl compound and a structural unit based on a reactive compound, the monomer mass-equivalent content ratio of these structural units in the crosslinkable polymer (lower alkyl compound: reaction). The sex compound) is preferably 90:10 to 99.9: 0.1, more preferably 95: 5 to 99.5: 0.5.
By setting the above ratio in this range, it becomes easy to set the stress residual ratio in a suitable range for the adhesive layer containing the crosslinked structure based on the obtained crosslinkable polymer.

The crosslinkable polymer used for the pressure-sensitive adhesive layer may further contain a structural unit based on an ethylenically unsaturated group-containing morphophosphorus compound. In the present specification, the "ethylenically unsaturated group-containing morphophosphorus compound" is also referred to as a "morphophosphorus compound".
Since the morpholine group has a function of accelerating the reaction of the cross-linking agent described later, the cross-linking polymer becomes a polymer having a functional group having a cross-linking promoting function by containing a structural unit based on the morphophosphorus compound. .. In this case, as compared with the case where a low molecular weight cross-linking accelerator described later is contained, it is possible to increase the cross-linking density of the adhesive layer while reducing the possibility of outgas generation, which is preferable.
Specific examples of the morpholin-based compound include N-vinylmorpholin, N-allylmorpholin, and N- (meth) acryloylmorpholin. Among the morpholine compounds, N- (meth) acryloylmorpholine, which is also an acrylic compound, is preferable from the viewpoint of good copolymerizability with compounds related to other constituent units. As the morphophosphorus compound, one kind may be used, or a plurality of kinds may be used.

The content of the structural unit based on the morpholine compound in the crosslinkable polymer related to the adhesive layer is based on the lower alkyl compound from the viewpoint of facilitating the generation of outgas while keeping the stress residual rate within the above range. 2 to 30 parts by mass is preferable, and 4 to 25 parts by mass is more preferable with respect to 100 parts by mass in total of the mass-equivalent content of the lower alkyl compound of the constituent unit and the mass-equivalent content of the reactive compound of the constituent unit based on the reactive compound. preferable.

The crosslinkable polymer related to the adhesive layer is a structural unit based on a compound having an ethylenically unsaturated bond other than the above-mentioned structural unit based on the lower alkyl compound, the structural unit based on the reactive compound and the structural unit based on the morpholine compound. May include. Specific examples of the monomer giving such a structural unit include olefins, carboxylic acid vinyl esters, aromatics having an ethylenically unsaturated bond, and the like, as in the case of the other polymerizable compounds described above. Alternatively, a compound having a functional group having a cross-linking promoting function similar to the morpholine compound, such as an ethylenically unsaturated group-containing imidazole compound, is also exemplified.
The content of the structural unit based on such a compound is not particularly limited, but if it is excessively large, it may be difficult to control the stress residual ratio within the above range. Therefore, the content is 10 parts by mass with respect to 100 parts by mass of the total of the lower alkyl compound mass-equivalent content of the constituent unit based on the lower alkyl compound and the reactive compound mass-equivalent content of the constituent unit based on the reactive compound. Is preferably the upper limit, and more preferably 5 parts by mass is the upper limit.

(Ii) Cross-linking agent As the cross-linking agent, a polyvalent isocyanate compound, a melamine compound, an epoxy compound and the like can be used. Multivalent isocyanate compounds are preferably used because they are fast-crosslinked and do not easily generate low-molecular-weight compounds that cause outgas and contamination.
As the polyvalent isocyanate compound, hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate and the like are commercially available and are preferably used.
Further, as the cross-linking agent, a polyisocyanate compound and an isocyanurate compound obtained by addition-reacting these polyhydric isocyanate compounds with trimethylolpropane or the like, a bullet-type compound and the like can also be used. Further, as a cross-linking agent, a urethane prepolymer type polyisocyanate obtained by addition-reacting these polyhydric isocyanate compounds with known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols and the like. Etc. may be used.

(Iii) Other components The adhesive layer may contain various components as long as it does not deviate from the object of the present invention.
Examples of such components include cross-linking accelerators, coloring materials such as dyes and pigments, antioxidants such as anilides and phenols, ultraviolet absorbers such as benzophenone and benzotriazole, plasticizers and antioxidants. , Photostabilizers, dispersants, leveling agents and the like are exemplified. However, it is preferable that these components do not easily generate outgas and do not impair the transparency of the adhesive layer.

There is no limit to the thickness of the adhesive layer.
Here, if the adhesive layer is excessively thin, there is a concern that the desired adhesive properties cannot be obtained, and if it is excessively thick, there is a concern that it will be disadvantageous from the viewpoint of workability.
Therefore, the thickness of the pressure-sensitive adhesive layer as a whole is usually selected in the range of 4 to 30 μm, preferably in the range of 6 to 25 μm.

In the transparent screen for aquarium of the present invention, the adhesive layer (first adhesive layer 6 in FIG. 1) bonded to the acrylic plate for aquarium has an initial adhesive strength of 3.0 N / 25 mm or more and an adhesive strength over time. It is 4.0 to 20.0 N / 25 mm.
In the present invention, the adhesive force (peeling force) of the adhesive layer is the adhesive force to the water tank acrylic plate (water tank acrylic resin).
Further, in the present invention, the adhesive force with time is the adhesive force after 4 days have passed under the conditions of a temperature of 85 ° C. and a humidity of 10% RH.
The transparent screen for aquarium of the present invention has an initial adhesive strength of 3.0 N / 25 mm or more and an adhesive strength over time of 4.0 N / 25 mm or more, so that it can be attached to an acrylic plate for aquarium (aquarium). In addition, it is possible to prevent air from entering between the acrylic plate for the aquarium and the transparent screen for the aquarium and generating bubbles during the period of use. Further, the transparent screen for aquarium of the present invention can be peeled off even after long-term use by setting the adhesive strength with time to 4.0 to 20.0 N / 25 mm, and the transparent screen for aquarium can be used for aquarium. It is also possible to prevent the so-called adhesive residue, in which the adhesive layer remains on the aquarium acrylic plate when peeled from the acrylic plate.

In the transparent screen for aquarium of the present invention, the adhesive layer has an initial adhesive strength of 3.0 N / 25 mm or more. The initial adhesive strength of the adhesive layer is preferably 4.0 N / 25 mm or more, more preferably 5.0 N / 25 mm or more.
If the initial adhesive strength is less than 3.0 N / 25 mm, it is not possible to prevent air from entering between the acrylic plate for the aquarium and the transparent screen for the aquarium to generate air bubbles during the period of use, and the transparent screen is temporarily fastened. Due to poor adhesion, it is easy to peel off and workability is reduced. Further, by setting the initial adhesive force to 3.0 N / 25 mm or more, the transparent screen does not peel off in the process of attaching water to the acrylic plate for aquarium.
The upper limit of the initial adhesive force of the adhesive layer is not limited, but is preferably 10.0 N / 25 mm or less, more preferably 9.0 N / 25 mm or less, and further preferably 8.0 N / 25 mm or less.
By setting the initial adhesive strength of the adhesive layer to 10.0 N / 25 mm or less, it is easy to peel off the transparent screen for the aquarium from the acrylic plate for the aquarium after long-term use, that is, to reattach the transparent screen for the aquarium. be able to.
The initial adhesive strength of the adhesive layer can be controlled by adjusting the amount of the cross-linking agent used in the above-mentioned adhesive composition. Specifically, the content of the cross-linking agent in the pressure-sensitive adhesive composition (adhesive layer) before the reaction for forming the cross-linked structure proceeds is set to 0. By adjusting in the range of 1 to 10 parts by mass, it becomes easy to set the initial adhesive force of the adhesive layer in the above range.

In the transparent screen for a water tank of the present invention, the adhesive layer has an adhesive force over time of 4.0 to 20.0 N / 25 mm. The adhesive strength of the adhesive layer over time is preferably 6.0 to 18.0 N / 25 mm, more preferably 8.0 to 16.0 N / 25 mm.
If the adhesive strength of the adhesive layer over time is less than 4.0 N / 25 mm, it is not possible to prevent air from entering between the acrylic plate for the aquarium and the transparent screen for the aquarium to generate bubbles during the period of use, and for the aquarium. Sufficient adhesive strength cannot be obtained when bonded to the acrylic plate, and peeling easily occurs between the surface of the acrylic plate for aquarium and the adhesive layer during use. On the contrary, when the adhesive strength of the adhesive layer over time exceeds 20.0 N / 25 mm, the adhesive strength is too large, and when the transparent screen for the aquarium is peeled off from the acrylic plate for the aquarium after long-term use, the acrylic plate for the aquarium becomes used. In addition to the adhesive residue remaining on the adhesive layer, which makes it difficult to peel off by hand, the transparent support may be destroyed.
The pressure of the pressure-sensitive adhesive layer can be controlled by adjusting the amount of the cross-linking agent used in the above-mentioned pressure-sensitive adhesive composition so that the power of the pressure-sensitive adhesive layer falls within this range.

There is no limit to the storage elastic modulus of the adhesive layer. The storage elastic modulus of the adhesive layer ^{is preferably 1.0 × 10 5} to 1.0 × 10 ⁸ Pa, more preferably 5.0 × 10 ⁵ to 5.0 × 10 ⁷ Pa, and more preferably 1.0 × 10 ⁶ to 1.0. 1.0 × 10 ⁷ Pa is more preferable.
By setting the storage elastic modulus of the adhesive layer to 1.0 × 10 ⁵ Pa or more, sufficient adhesive strength is obtained when the transparent screen for the aquarium is peeled off from the acrylic plate for the aquarium, and the generation of adhesive residue is prevented. It can be prevented more preferably. By setting the storage elastic modulus of the adhesive layer to 1.0 × 10 ⁸ Pa or less, it becomes possible to easily peel off the transparent screen for the aquarium from the acrylic plate for the aquarium after long-term use. Further, it is possible to preferably prevent the transparent support from being destroyed during peeling.
The storage elastic modulus of the pressure-sensitive adhesive layer can be controlled by adjusting the amount of the cross-linking agent used in the above-mentioned pressure-sensitive adhesive composition so that the storage elastic modulus is in this range.

There is no limit to the haze of the adhesive layer used in the transparent screen for the aquarium. The adhesive layer preferably has a low internal haze so as not to impair the transparency when it is attached to the acrylic plate for aquarium. The internal haze of the adhesive layer is preferably less than 0.8%, more preferably less than 0.5%, still more preferably less than 0.2%.
By setting the internal haze of the adhesive layer to less than 0.8%, the transparency of the water tank to which the acrylic plate for the water tank is attached can be appropriately ensured, and a water tank having good internal visibility can be obtained.
The internal haze of the pressure-sensitive adhesive layer can be controlled by selecting the combination of the cross-linking polymer and the cross-linking agent in the above-mentioned pressure-sensitive adhesive composition and other components so that the internal haze falls within this range.

[Transparent support]
The transparent support supports the above-mentioned reflective layer, adhesive layer, and the like.
As the transparent support in the present invention, resin films such as TAC (triacetyl cellulose) and PET (polyethylene terephthalate) can be appropriately used.
The thickness of the transparent support is not limited, but is preferably 15 to 75 μm. As the transparent support, a commercially available product having a thickness in this range can be preferably used.
By setting the thickness of the transparent support to 15 μm or more, it is possible to secure appropriate elasticity and strength as a film and improve handleability. Further, by setting the thickness of the transparent support to 75 μm or less, it is possible to suppress the occurrence of warpage of the film end portion during construction and prevent peeling due to this.
The thickness of the transparent support in the present invention is more preferably 25 to 50 μm.
The surface of the transparent support on the adhesive layer side may be subjected to corona treatment or an easy-adhesive coating such as acrylic for the purpose of enhancing the adhesive force with the adhesive layer.

The transparent screen for an aquarium of the present invention may further have a protective adhesive film (protective film) on the surface of the adhesive layer and / or the light reflecting layer before being attached to the acrylic plate for the aquarium.
In the present invention, since a resin film such as PET having excellent transparency is used as the transparent support of the transparent screen for the water tank, it is possible to perform an optical inspection with the protective adhesive film attached. be.
Here, the protective adhesive film preferably has a total light transmittance of 85% or more and a haze value of less than 0.8%. By setting the total light transmittance of the protective adhesive film to 85% or more and the haze value to less than 0.8%, transparency is ensured and the accuracy of optical inspection with the protective adhesive film attached is improved. Can be high.

As described above, in the transparent screen for aquarium of the present invention, an adhesive sheet composed of only an adhesive layer can be used, but a double-sided adhesive sheet having adhesive layers on both sides of a resin film can also be preferably used.
When a double-sided pressure-sensitive adhesive sheet is used in the transparent screen for a water tank of the present invention, as an example, the resin film serves as the transparent support described above in the present invention, and one of the pressure-sensitive adhesive layers is bonded to the acrylic plate for the water tank. , The above-mentioned adhesive layer having initial and continuous adhesive strength. The other adhesive layer is, for example, bonded to some layer (film, sheet-like material, plate-like material) constituting the transparent screen for aquarium, such as a light reflection layer.

In the transparent screen for aquarium of the present invention, as an example of the configuration using the double-sided adhesive sheet, the transparent screen for aquarium of FIG. 1 described above is exemplified.
In this case, for example, as shown in the transparent screen for a water tank in FIG. 1, the resin film of the double-sided pressure-sensitive adhesive sheet serves as the first transparent support 5, and one of the pressure-sensitive adhesive layers is bonded to the acrylic plate for the water tank. 1 is an adhesive layer 6, and the other adhesive layer is a second adhesive layer 4 to be bonded to the second transparent support 3.

In the transparent screen for aquarium of the present invention using the double-sided adhesive sheet having adhesive layers on both sides of the resin film, the adhesive layer bonded to the acrylic plate for the aquarium, that is, the first adhesive layer 6 in FIG. It has initial adhesive strength and adhesive strength over time. By adhering this adhesive layer to the aquarium acrylic plate, it can be attached to the aquarium acrylic plate without generating bubbles, and can be peeled off from the aquarium acrylic plate as needed. In addition, as described above, no adhesive residue is generated on the acrylic plate for the aquarium.

On the other hand, among the adhesive layers of the double-sided adhesive sheet, the adhesive layer that is not bonded to the acrylic plate for the water tank, that is, the second adhesive layer 4 that is bonded to the second transparent support 3 in FIG. 1 is shown below. It preferably contains a cross-linked structure formed by reacting a cross-linking agent with a polymer having a reactive functional group (cross-linking polymer) which is a functional group capable of reacting with the cross-linking agent. By using this adhesive layer, it is possible to prevent the adhesive layer and the layer attached to the adhesive layer, that is, the second transparent support 3 in FIG. 1, from being unnecessarily peeled off.
As described above, in the transparent screen for aquarium shown in FIG. 1, the alignment layer 2 and the second transparent support 3 are not essential constituent requirements. Therefore, in the transparent screen for aquarium shown in FIG. 1, the second adhesive layer 4 may be bonded to the alignment layer 2 instead of the second transparent support 3, or the light reflection layer 1 (cholesteric liquid crystal layer). ) May be attached.

In the following description, the inner adhesive layer that is not used for bonding with the water tank acrylic plate is referred to as the "second adhesive layer" following the transparent screen for the water tank in FIG.

(I) Crosslinkable polymer The crosslinkable polymer related to the second adhesive layer is preferably an acrylic polymer having a reduced carboxyl group content from the viewpoint of further reducing the amount of outgas from the double-sided adhesive sheet. .. Specifically, the content of the carboxyl group in the crosslinkable polymer is 1.0 part by mass or less of the structural unit having a carboxyl group with respect to 100 parts by mass of the total amount of the monomers for forming the crosslinkable polymer. It is preferably present, and more preferably 0.5 parts by mass or less. Furthermore, the crosslinkable polymer is preferably an acrylic polymer having no carboxyl group. As described above, in the present specification, an acrylic polymer having no carboxyl group is also referred to as a "carboxyl group-free polymer".
Similarly, the second adhesive layer preferably has a low content of a carboxyl group, and further preferably does not substantially contain a component having a carboxyl group. Examples of the structural unit having a carboxyl group include acrylic acid, methacrylic acid, and itaconic acid.

The structural unit of the crosslinkable polymer is not particularly limited.
The crosslinkable polymer may be composed of only a structural unit based on an acrylic compound which is one or more compounds of a compound having a (meth) acryloyl group and a derivative thereof (ester, acrylonitrile, etc.). It may contain a structural unit based on an acrylic compound and a structural unit based on a compound other than the acrylic compound.
In addition, "(meth) acryloyl group" in this specification means both acryloyl group and metalloyl group. The same applies to other similar terms in this regard. Further, the compound other than the above-mentioned acrylic compound may be composed of one kind of compound or may be composed of a plurality of kinds of compounds.

Among these, the crosslinkable polymer preferably contains a structural unit based on an alkyl (meth) acrylate having an alkyl group having 4 or less carbon atoms. As described above, in the present specification, "alkyl (meth) acrylates having an alkyl group having 4 or less carbon atoms" are also referred to as "lower alkyl compounds".
Specific examples of such lower alkyl compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Examples thereof include acrylates, sec-butyl (meth) acrylates, and tert-butyl (meth) acrylates.

Among these, n-butyl (meth) acrylate and methyl (meth) acrylate from the viewpoint of facilitating an appropriate balance between enhancing the adhesive properties of the second adhesive layer and reducing the amount of outgas. Etc. are preferable. The lower alkyl compound may be used alone or in combination of two or more.

Examples of the monomer giving a structural unit based on a compound other than the acrylic compound include olefins such as ethylene and norbornene, carboxylic acid vinyl esters such as vinyl acetate, and aromatic compounds having an ethylenically unsaturated bond such as styrene. As described above, in the present specification, "a monomer that gives a structural unit based on a compound other than an acrylic compound" is also referred to as "another polymerizable compound".

The reactive functional group of the crosslinkable polymer related to the second adhesive layer is preferably a functional group capable of reacting with the isocyanate group because the crosslinking agent contains a tolylene diisocyanate compound as described later. Examples of such functional groups other than the carboxyl group include a hydroxyl group, an amino group, and an amide group.

In the crosslinkable polymer, the type of the compound that gives a structural unit having a reactive functional group is not particularly limited.
Examples thereof include the above-mentioned (meth) acrylate having a hydroxyl group and the (meth) acrylate having an amino group. Examples of the ethylenically unsaturated compound having such a reactive functional group include an ethylenically unsaturated compound containing an amide group and an alcohol having a vinyl group. As described above, in the present specification, the "ethylenically unsaturated compound having a reactive functional group" is also referred to as a "reactive compound".
Specific examples of such reactive compounds include acrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, 5-hexene-1-ol, 5-hexene-3. -All, 4-pentene-1-all and the like can be mentioned.

When such a crosslinkable polymer contains a structural unit based on a lower alkyl compound and a structural unit based on a reactive compound, the monomer mass-equivalent content ratio of these structural units in the crosslinkable polymer (lower alkyl compound: reaction). The sex compound) is preferably 90:10 to 99.9: 0.1, more preferably 95: 5 to 99.5: 0.5.
By setting the above ratio in this range, it becomes easy for the second adhesive layer containing the crosslinked structure based on the obtained crosslinkable polymer to have a stress residual ratio in a suitable range.

The crosslinkable polymer used for the second adhesive layer may further contain a structural unit based on an ethylenically unsaturated group-containing morphophosphorus compound. As described above, in the present specification, the "ethylenically unsaturated group-containing morphophosphorus compound" is also referred to as a "morphophosphorus compound".
Since the morpholine group has a function of accelerating the reaction of the cross-linking agent described later, the cross-linking polymer becomes a polymer having a functional group having a cross-linking promoting function by containing a structural unit based on the morphophosphorus compound. .. In this case, as compared with the case where a low molecular weight cross-linking accelerator described later is contained, it is possible to increase the cross-linking density of the adhesive layer while reducing the possibility of outgas generation, which is preferable.
Specific examples of the morpholin-based compound include N-vinylmorpholin, N-allylmorpholin, and N- (meth) acryloylmorpholin. Among the morpholine compounds, N- (meth) acryloylmorpholine, which is also an acrylic compound, is preferable from the viewpoint of good copolymerizability with compounds related to other constituent units. As the morphophosphorus compound, one kind may be used, or a plurality of kinds may be used.

The content of the structural unit based on the morpholine compound in the crosslinkable polymer related to the second adhesive layer is a lower alkyl compound from the viewpoint of facilitating the generation of outgas while keeping the stress residual ratio within the above range. 2 to 30 parts by mass is preferable with respect to 100 parts by mass of the total of the lower alkyl compound mass-equivalent content of the constituent unit based on the above and the reactive compound mass-equivalent content of the constituent unit based on the reactive compound. Is more preferable.

The crosslinkable polymer according to the second adhesive layer is based on a compound having an ethylenically unsaturated bond other than the above-mentioned structural unit based on the lower alkyl compound, the structural unit based on the reactive compound and the structural unit based on the morpholine compound. It may include a structural unit. Specific examples of the monomer giving such a structural unit include olefins, carboxylic acid vinyl esters, and aromatics having an ethylenically unsaturated bond, as in the case of the other polymerizable compounds described above. Alternatively, a compound having a functional group having a cross-linking promoting function similar to the morpholine compound, such as an ethylenically unsaturated group-containing imidazole compound, is also exemplified.
The content of the structural unit based on such a compound is not particularly limited, but if it is excessively large, it may be difficult to control the stress residual ratio within the above range. Therefore, the content is 10 parts by mass with respect to 100 parts by mass of the total of the lower alkyl compound mass-equivalent content of the constituent unit based on the lower alkyl compound and the reactive compound mass-equivalent content of the constituent unit based on the reactive compound. Is preferably the upper limit, and more preferably 5 parts by mass is the upper limit.

(Ii) Cross-linking agent The cross-linking agent for the second adhesive layer contains one or more compounds selected from the group consisting of toluene diisocyanate (TDI) and its derivatives. In the present specification, tolylene diisocyanate (TDI) and its derivatives are also referred to as "toluene diisocyanate-based cross-linking agent" and may be abbreviated as "TDI-based cross-linking agent".
The cross-linking agent for the second adhesive layer preferably contains a TDI-based cross-linking agent as a main component, more preferably a TDI-based cross-linking agent, and even more preferably substantially TDI.
Specific examples of the TDI-based cross-linking agent include polyisocyanate compounds and isocyanurates obtained by addition reaction with trimethylolpropane and the like, bullet-type compounds, and known polyether polyols and polyester polyols, acrylic polyols, polybutadiene polyols, and Examples thereof include a urethane prepolymer type polyisocyanate obtained by subjecting a polyisoprene polyol or the like to an addition reaction.
When the cross-linking agent contains a TDI-based cross-linking agent, the double-sided pressure-sensitive adhesive sheet is bent as compared with the case where other polyisocyanate compounds such as xylylene diisocyanate (XDI) and hexamethylene diisocyanate (HMDI) are contained. Even if an external force is applied to the adhesive layer, stress is unlikely to remain in the adhesive layer.

The gel fraction of the second adhesive layer is preferably 10 to 70%, more preferably 20 to 60%. By adjusting the amount of the above-mentioned cross-linking agent used so that the gel fraction of the adhesive layer is within this range, it becomes easy to set the stress residual ratio within the above-mentioned range.
Specifically, the content of the cross-linking agent in the adhesive layer before the reaction for forming the cross-linking structure proceeds is 0.1 to 10 parts by mass with respect to 100 parts by mass of the above-mentioned cross-linking polymer. By adjusting the range, it becomes easy to set the gel fraction of the adhesive layer within the above range.

(Iii) Other components The second adhesive layer can contain various components as long as it does not deviate from the object of the present invention.
Examples of such components include cross-linking accelerators, coloring materials such as dyes and pigments, antioxidants such as anilides and phenols, ultraviolet absorbers such as benzophenone and benzotriazole, plasticizers and antioxidants. , Photostabilizers, dispersants, leveling agents and the like are exemplified. However, it is preferable that these components do not easily generate outgas.

(Iv) Thickness The thickness of the second adhesive layer is not particularly limited.
If it is excessively thin, there is a concern that the desired adhesive properties cannot be obtained, and if it is excessively thick, there is a concern that it will be disadvantageous from the viewpoint of processability. Therefore, the thickness of the second adhesive layer is usually selected in the range of 4 to 30 μm, preferably in the range of 6 to 25 μm for the entire adhesive layer.

The transparent screen for aquarium of the present invention is not limited to the configuration shown in FIG. That is, various configurations can be used as long as the transparent screen for an aquarium of the present invention has an adhesive layer, a transparent support, and a light reflecting layer in this order.
In the example shown below, the light reflecting layer may have the above-mentioned cholesteric liquid crystal layer.

FIG. 3 shows an explanatory diagram of the layer structure of the embodiment of another preferable transparent screen for aquarium. The transparent screen for an aquarium of the present invention may have a protective layer for protecting the light reflecting layer, as conceptually shown in FIG.
The transparent screen for an aquarium shown in FIG. 3 includes a binder and a light reflecting layer 21 containing fine particles dispersed in the binder on one surface of the transparent support 23. The protective layer 22 is further laminated on the light reflecting layer 21. Further, the adhesive layer 24 is laminated on the other surface of the transparent support 23 (the surface opposite to the light reflecting layer 21).
As the protective layer 22, there is no limitation, and various known sheet-like materials can be used as long as they have sufficient light transmission. As an example, various resin films exemplified by the above-mentioned transparent support are exemplified.

Further, as another example, a transparent screen for an aquarium having an optical shape layer and a light reflecting layer is also preferably used.
For example, the transparent screen having an optical shape layer having a circular Frenel lens shape and a reflective layer of a half mirror described in paragraphs [0017] to [0033] of JP-A-2017-156452 is reflected by the reflective layer. Only light is diffused, transmitted light is not diffused. As a result, it is possible to display a projected image having a good viewing angle and resolution, and the water tank on the other side of the transparent screen is not blurred or blurred, and is well visible and high transparency can be realized.

The layer structure of an example of the transparent screen for an aquarium having the optical shape layer and the light reflection layer is conceptually shown in FIG.
The transparent screen for a water tank shown in FIG. 2 has an adhesive layer 16, a transparent support 11, a first optical shape layer 12, a light reflection layer 13, a second optical shape layer 14, and a protective layer in this order from the water tank acrylic plate side. It is equipped with fifteen.

[Manufacturing method of transparent screen for aquarium and aquarium]
The method for producing a transparent screen for a water tank of the present invention can be produced, for example, by applying an adhesive composition to a laminate having a light-reflecting layer formed on a transparent support to form the adhesive layer. The water tank of the present invention can be manufactured by attaching the transparent screen for a water tank thus produced to an acrylic plate for a water tank constituting the water tank via an adhesive layer.
Further, after the adhesive layer is applied on a support different from the transparent support, only the adhesive layer may be transferred from the support and the adhesive layer may be provided on the laminated body in which the light reflecting layer is formed on the transparent support. ..
Alternatively, after producing a film with a double-sided adhesive in which adhesive layers are applied to both sides of a support different from the transparent support, a laminate having a light-reflecting layer formed on the transparent support and an acrylic plate for a water tank are used. The transparent screen for a water tank and the water tank of the present invention may be made by laminating via a film with a double-sided adhesive.
The coating method (coating method) for forming the above-mentioned adhesive layer is not particularly limited, and various known coating methods can be used, for example, a die coater, a comma coater, a knife coater, and a gravure coater. Also, a roll coater or the like can be used.

In order to improve the adhesion between the adhesive layer and the transparent support and / or the aquarium acrylic plate, the surface of the transparent support and / or the aquarium acrylic plate may be subjected to easy-adhesion treatment such as corona treatment. can. An easy-adhesion layer may be provided on the surface of the transparent support and / or the acrylic plate for the aquarium.

Such a transparent screen for an aquarium of the present invention has a total light transmittance of 70% or more.
By setting the total light transmittance to 70% or more, it is possible to suitably observe the inside of the aquarium in the aquarium to which the transparent screen for the aquarium is attached, both when the projected image is displayed and when the projected image is not displayed. become.

The transparent image display system of the present invention projects the projected light from the viewing side to the water tank of the present invention to which the transparent screen for the water tank of the present invention is attached by a projector.
That is, in the transparent image display system of the present invention, the projected light is projected from the visual recognition side by the projector onto the water tank of the present invention to which the transparent screen for the water tank of the present invention is attached, and the projected light is projected on the light reflecting layer of the transparent screen for the water tank. It is an image display system that displays the image projected by the projector by superimposing it on the scene inside the water tank by reflecting it with.
In the transparent image display system of the present invention, the projector is not limited, and various known projectors used in known image projection devices (image projection systems) can be used.

(Preparation of transparent acrylic plate)
A 300 mm square and 5 mm thick transparent acrylic plate (Sumipex # 000 [manufactured by Sumika Acrylic Co., Ltd.]) was prepared and the surface was washed.
The acrylic resin of this transparent acrylic plate is the same resin as the acrylic plate for aquariums.

(Preparation of light reflecting layer)
The display member RS-14 described in Example 13 of JP-A-2018-2004569 was prepared as a light reflecting layer.
The display member RS-14 has a cholesteric liquid crystal layer as a reflective layer.

(Preparation of adhesive composition)
The pressure-sensitive adhesive composition 1 was prepared with the following composition.
(Adhesive Composition 1)
85 parts by mass of butyl acrylate, 15 parts by mass of methyl acrylate, 1 part by mass of acrylate, and 0.5 parts by mass of benzoyl peroxide are dissolved in ethyl acetate so as to have a monomer concentration of 40% by mass, and then 60 ° C. The polymer solution 1 (mass average molecular weight 1.1 million) was obtained by polymerizing for 9 hours.
Further, 45 parts by mass of butyl acrylate, 55 parts by mass of methyl methacrylate, 1 part by mass of acrylate, and 0.5 parts by mass of benzoyl peroxide are dissolved in toluene so as to have a monomer concentration of 20% by mass, and then 60. Polymerization at ° C. for 9 hours gave Polymer Solution 2 (mass average molecular weight 60,000).
65 parts by mass of solid content of polymer solution 1, 35 parts by mass of solid content of

polymer solution

2, 1 part by mass of isocyanate-based cross-linking agent (trade name: Coronate L [manufactured by Nippon Polyurethane Co., Ltd.]), and epoxy-based cross-linking agent (trade name). : Tetrad C [manufactured by Mitsubishi Chemical Corporation]) 0.05 parts by mass was mixed to prepare the pressure-sensitive adhesive composition 1.

(Preparation of adhesive sheet 1)
A PET film having a thickness of 25 μm was prepared.
The pressure-sensitive adhesive composition 1 was applied to both sides of this PET film so that the film thickness after drying was 25 μm. Then, it was dried and aged at 90 to 110 ° C. for 30 to 120 seconds to prepare a pressure-sensitive adhesive sheet 1 having adhesive layers on both sides of the PET film.
An easily peelable PET film whose surface was mold-released was laminated on the surface of each of the formed adhesive layers to form a protective film.

(Making a transparent screen for an aquarium)
One of the protective sheets of the adhesive sheet 1 obtained above is peeled off, and the surface of the support of the above-mentioned display member RS-14 is bonded to the exposed adhesive layer to prepare a transparent screen for a water tank of Example 1 Sample 1. did.

(Making a transparent acrylic plate with a transparent screen for aquarium attached)
The obtained transparent screen for aquarium was attached to a transparent acrylic plate which is the same resin as the above-mentioned acrylic plate for aquarium.
Specifically, the protective film was peeled off from the obtained transparent screen for aquarium, and the surface of the exposed adhesive layer and the surface of the transparent acrylic plate wet with water were brought into close contact with each other. After that, the air existing between the adhesive layer and the transparent acrylic plate was scraped out from the transparent screen side for the water tank with a rubber squeegee, and both were attached.
After that, the following evaluation was carried out.

(Evaluation 1) [Initial adhesive strength]
The initial adhesive force (initial peeling force) of the adhesive layer in the present invention is a value measured according to JIS Z0237: 2000.
When measuring the adhesive strength, first, cut the prepared transparent screen for aquarium into a size of 25 mm x 150 mm, and wet it with water (Sumipex # 000 [manufactured by Sumika Acrylic Co., Ltd.], acrylic plate for aquarium. It is bonded to the same resin), crimped once back and forth with a 2 kg rubber roller, and left for 24 hours under the conditions of a temperature of 25 ° C. and a humidity of 55% RH.
Then, the adhesive strength is measured using a tensile tester (unit: N / 25 mm). The measurement conditions at this time are 180 ° peeling, temperature 25 ° C., humidity 55% RH, and peeling speed 300 mm / min.
(Evaluation 2) [Adhesive strength over time]
The adhesive force over time (peeling force over time) of the adhesive layer is evaluated after the prepared bonded product of the transparent screen for a water tank and the transparent acrylic plate is dried under the conditions of a temperature of 85 ° C. and a humidity of 10% RH for 4 days. The adhesive strength was measured by the same method as the initial adhesive strength of 1.
(Evaluation 3) [Remaining glue]
The adhesive residue of the adhesive layer is a test for visually evaluating the presence or absence of adhesive residue on the surface of the transparent acrylic plate when the transparent screen for the water tank is peeled off from the transparent acrylic plate in the evaluation of the adhesive strength over time in the above evaluation 2. be.
The above-mentioned "glue residue" in the present invention refers to a phenomenon in which a part of the adhesive layer remains on the surface of the transparent acrylic plate when the transparent screen for a water tank is peeled off from the transparent acrylic plate. In Table 1, those without adhesive residue are described as "A", and those with adhesive residue are described as "B". In addition, Table 1 shows "-" for those in which the adhesive strength over time was too strong and the transparent screen for the water tank could not be peeled off by hand from the transparent acrylic plate and the adhesive residue could not be evaluated.
(Evaluation 4) [Foam generation]
A transparent acrylic plate (Sumipex # 000 [manufactured by Sumika Acrylic Co., Ltd.], 2 mm thick) was attached to the prepared transparent screen for aquarium under the conditions of temperature 25 ° C and humidity 55% RH, and the temperature was 25 ° C. After being left for 24 hours under the condition of humidity 55% RH, it was put into each test condition.
After 250 hours, the sample was taken out and left for 24 hours under the conditions of temperature 25 ° C. and humidity 55% RH, and then visually observed whether or not bubbles were generated on the adhesive surface between the transparent screen for the aquarium and the transparent acrylic plate. .. Adhesive reliability was evaluated after a lapse of time according to the following criteria.
A: There are no bubbles on the adhesive surface between the transparent screen for the aquarium and the transparent acrylic plate.
B: Bubbles were generated on the adhesive surface between the transparent screen for the water tank and the transparent acrylic plate.

(Evaluation 5) [Storage modulus]
When the storage elastic modulus of the adhesive layer of the produced transparent screen for aquarium was measured by Tensilon (manufactured by Toyo Seiki Seisakusho), the storage elastic modulus was 3.80 MPa.
The sample size at the time of Tensilon measurement was 5 mm in width, 1 mm in thickness, and 10 mm in length between chucks, and the tensile speed was 10 mm / min (temperature 25 ° C., humidity 55% RH). The storage elastic modulus of the other samples shown in Table 1 was also measured under the same conditions.
(Evaluation 6) [Internal haze]
A drop of immersion oil for microscopic observation [manufactured by Nikon Corporation] was further dropped onto the adhesive layer of the prepared transparent screen for aquarium, and an acrylic plate having a length of 40 mm, a width of 40 mm and a thickness of 2 mm was placed on the drop. This was used as a sample for internal haze measurement.
When the internal haze was measured using a haze meter (NDH4000 [manufactured by Nippon Denshoku Kogyo Co., Ltd.]), the internal haze was 0.2%. Haze was measured based on JIS-K7136.
The internal haze of the other samples shown in Table 1 was also measured under the same conditions.

(Evaluation 7) [Reflectance]
Three-dimensional variable angle spectroscopy by appropriately setting the incident angle (extreme angle and azimuth angle), light receiving angle (extreme angle and azimuth angle), and measurement wavelength region so that light is incident from the light reflecting layer side. Reflectance R [45, 30] (550) and reflectance R [-45, 15] of a transparent screen for a water tank manufactured using a color measurement system (GCMS-3B [manufactured by Murakami Color Technology Laboratory]). ] (550) was measured.
Here, R [-45, θ] (550) receives light with a polar angle θ at an azimuth angle 180 ° deviated from the azimuth angle of the incident light with respect to the incident light having a polar angle −45 ° on the transparent screen. Reflectance at a wavelength of 550 nm, measured at an angle.

(Evaluation 8) [Total light transmittance]
When the total light transmittance of the produced transparent screen for a water tank was measured using a haze meter (NDH4000 [manufactured by Nippon Denshoku Kogyo Co., Ltd.]), the total light transmittance was 78%. The total light transmittance was measured based on JIS-K7136.
The total light transmittance of the other samples shown in Table 1 was also measured under the same conditions.

The above evaluation results are shown in Table 1 below.

(Example 1 sample 2)
Example 1 In Sample 1, an adhesive layer made of the adhesive composition 1 is placed on one side, and an adhesive layer made of the same acrylic strong adhesive as PET-25WF (commercially available double-sided adhesive sheet, manufactured by Niei Shinka Co., Ltd.). The pressure-sensitive adhesive sheet 2 was produced in the same manner as the pressure-sensitive adhesive sheet 1 of the sample 1 except that the pressure-sensitive adhesive sheets 1 were formed on the opposite surfaces.
Same as Sample 1 of Example 1 except that the protective film on the pressure-sensitive adhesive layer side made of the above-mentioned strong acrylic adhesive of the pressure-sensitive adhesive sheet 2 was peeled off and the surface of the support of the above-mentioned display member RS-14 was bonded. Then, a transparent screen for a water tank of Example 1 Sample 2 was obtained.

(Example 1 sample 3)
A transparent screen for a water tank of Example 1 Sample 3 was obtained in the same manner as in Example 1 Sample 1 except that the thickness of the PET film in the pressure-sensitive adhesive sheet 1 used in Example 1 Sample 1 was changed to 50 μm.

(Example 1 sample 4)
Example 1 Example 1 except that the amount of the isocyanate-based cross-linking agent of the pressure-sensitive adhesive composition 1 used in Sample 1 was changed to 3.0 parts by mass and the amount of the epoxy-based cross-linking agent was changed to 1.0 part by mass. In the same manner as in Sample 1, a transparent screen for a water tank of Example 1 Sample 4 was obtained.
The transparent screen for a water tank of Example 1 is, so to speak, a "cholesteric reflective transparent screen for a water tank" having a cholesteric liquid crystal layer as a light reflecting layer.

(Example 2)
Preparation of a transparent screen having an optical shape layer and a light-reflecting layer In Example 1 Sample 2, instead of the display member RS-14 used as the reflective layer, the first embodiment described in JP-A-2017-156452. Using the screen 10 of the first embodiment as a reflective layer, the protective film on the pressure-sensitive adhesive layer side made of the pressure-sensitive adhesive composition 1 of the pressure-sensitive adhesive sheet 2 was peeled off and bonded in the same manner as in Sample 2 of Example 1. A transparent screen for a water tank of Example 2 was obtained.

(Example 3)
Preparation of Light Diffusive Transparent Screen In Example 1 Sample 2, the transparent screen described in Example 1 of International Publication No. 2017/94550 was used as the reflective layer instead of the display member RS-14 used as the reflective layer. , The transparent screen for the water tank of Example 3 in the same manner as in Example 1 Sample 2 of the present invention, except that the protective film on the adhesive layer side made of the adhesive composition 1 of the adhesive sheet 2 was peeled off and bonded. Got

(Comparative Example 1 Sample 11)
Transparent screen using a commercially available double-sided adhesive sheet Example 1 Instead of the adhesive sheet 1 used in Sample 1, PET-25WF (commercially available double-sided adhesive sheet [manufactured by Niei Shinka Co., Ltd.]) was used for bonding. A transparent screen for a water tank of Comparative Example 1 Sample 11 was obtained in the same manner as in Example 1 Sample 1 except for the above.

(Comparative Example 1 Sample 12)
Example 1 Sample 1 Except that the amount of the isocyanate-based cross-linking agent of the pressure-sensitive adhesive composition 1 used in Sample 1 was changed to 0.5 parts by mass and the amount of the epoxy-based cross-linking agent was changed to 0 parts by mass. In the same manner as above, a transparent screen for a water tank of Comparative Example 1 Sample 12 was obtained.

(Comparative Example 1 Sample 13)
Example 1 Example 1 except that the amount of the isocyanate-based cross-linking agent of the pressure-sensitive adhesive composition 1 used in Sample 1 was changed to 3.0 parts by mass and the amount of the epoxy-based cross-linking agent was changed to 5.0 parts by mass. In the same manner as in Sample 1, a transparent screen for a water tank of Comparative Example 1 Sample 13 was obtained.
That is, the transparent screen for a water tank of Comparative Example 1 is also a so-called "cholesteric reflective transparent screen for a water tank" having a cholesteric liquid crystal layer as a light reflecting layer.

(Comparative Example 2)
In the pressure-sensitive adhesive sheet 2 of Example 3, PS-D1 (commercially available pressure-sensitive adhesive sheet [manufactured by Panac]) was used instead of the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition 1 for bonding, except that the pressure-sensitive adhesive sheet 2 was bonded to Example 3. In the same manner, a transparent screen for a water tank of Comparative Example 2 was obtained.

Table 1 shows the results of evaluating Samples 2 to 4, Examples 2 and 3, and Samples 11 to 13 and Comparative Example 2 of Comparative Example 1 in the same manner as Sample 1 of Example 1. ..

From Table 1, Samples 1 to 4, Example 2 and Example 3 of Example 1 using the pressure-sensitive adhesive of the present invention had appropriate initial and aging peeling forces, and had no adhesive residue or foam generation. It can be seen that it is suitable as a transparent screen for aquariums.
In addition, the prepared transparent screen for the aquarium is attached to an acrylic aquarium (width 2 m x height 2 m), and the short focus projector TH671ST (DLP projection method, resolution 1080p, brightness 3000 lm, manufactured by BenQ) is 1.5 m from the aquarium. It was installed on the ceiling at a distance and projected. When confirmed from the front (0 degree) and diagonal (30 degrees and 45 degrees respectively on the left and right) positions of the water tank, R [45, 30] (550) / R [45, 15] (550) were found in all the samples. Since it is 1.3 or higher, the image projected on the reflective transparent screen for a water tank of the present invention can be clearly seen from any position. In particular, in Example 1, the shadow of a fish swimming in the aquarium could be visually recognized with high clarity.

1 Light reflection layer 2 Orientation layer 3 Second transparent support 4 Second adhesive layer 5 First transparent support 6 First adhesive layer 11 Transparent support 12 First optical shape layer 13 Light reflection layer 14 Second optical shape layer 15 Protective layer 16 Adhesive layer 21 Light reflection layer 22 Protective layer 23 Transparent support 24 Adhesive layer

Claims

A transparent screen for an aquarium having an adhesive layer, a transparent support, and a light reflecting layer in this order.
The total light transmittance is 70% or more,
The adhesive layer has an initial adhesive strength of 3.0 N / 25 mm or more, and has an adhesive strength over time of 4.0 to 20 after 4 days have passed under the conditions of a temperature of 85 ° C. and a humidity of 10% RH. It is 0.0N / 25mm,
A transparent screen for an aquarium that is attached to an acrylic plate for an aquarium via the adhesive layer and reflects the projected light projected from the projector to display an image on the projection side.
The transparent screen for an aquarium according to claim 1, wherein the initial adhesive force of the adhesive layer is 10 N / 25 mm or less.
The transparent screen for an aquarium according to claim 1 or 2, wherein the adhesive layer has a storage elastic modulus of 1.0 × 10 5 to 1.0 × 10 8 Pa at 25 ° C.
Any one of claims 1 to 3, wherein at least one of the light reflecting layers has a cholesteric liquid crystal layer, all the cholesteric liquid crystal layers have the same spiral sense, and the following formula (1) is satisfied. Transparent screen for water tank as described in.
R [45,30] (550) / R [45,15] (550) ≧ 1.3 Equation (1)
Here, R [-45, 30] (550) is a polar angle at an azimuth angle 180 ° deviated from the azimuth angle of the incident light with respect to the incident light having a polar angle −45 ° on the transparent screen for a water tank. Represents the reflectance at a wavelength of 550 nm, measured at a light receiving angle of 30 °, where R [45,15] (550) is the light incident on the transparent screen for the water tank at a polar angle of −45 °. It represents the reflectance at a wavelength of 550 nm, which is measured at a light receiving angle of a polar angle of 15 ° at an azimuth angle 180 ° deviated from the azimuth angle of the incident light.
The transparent screen for an aquarium according to any one of claims 1 to 4, further comprising a protective film on the side of the adhesive layer opposite to the transparent support.
A water tank in which the transparent screen for water tank according to any one of claims 1 to 5 is attached to the surface of the water tank made of an acrylic plate for water tank by the adhesive layer.
A transparent image display system that projects projected light from the viewing side into the water tank according to claim 6 by a projector so as to superimpose the projected light in the water tank and display an image by the projected light of the projector.