Mirror-type projection screen

Abstract

This mirror-type projection screen comprises a half-mirror film and a transparent screen layer laminated on one surface of the half mirror film. The transparent screen layer comprises a matrix component having light diffusion fine particles dispersed therein. This mirror-type projection screen can display good images while sufficiently functioning as a mirror. If the half-mirror film of the mirror-type projection screen does not include a metal-evaporated film, the function of a sensor such as a LiDAR sensor will not be hindered.

Description

Technical Field

[0001] The present invention relates to a mirror-type projection screen that can be used as a mirror and can display an image projected from a projector arranged behind it.

Background Art

[0002] In recent years, images (including the concept of video) have been displayed using projectors in various places. Among them, as an example, a transmissive projection screen used by being attached to glass such as a show window is becoming known. This transmissive projection screen displays an image projected from a projector to a viewer on the opposite side of the projector across the glass to which the transmissive projection screen is attached.

[0003] In Patent Documents 1 to 6, various projection screens including the above-described transmissive projection screen have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors are developing a mirror-type projection screen as a new form of projection screen as described above. This mirror-type projection screen can be used as a mirror while also displaying images projected from a projector positioned behind it. Users can use the mirror-type projection screen as a mirror while simultaneously viewing the image displayed on it.

[0006] In a mirror-type projection screen, the projector is positioned on the side of the screen opposite the viewer, and the image projected from the projector is displayed on the screen. This arrangement is the same as that of the transmissive projection screen described above. However, conventional transmissive projection screens cannot fully perform their function as mirrors and are therefore unsuitable for use as mirror-type projection screens.

[0007] Furthermore, the inventors are also considering using the aforementioned mirror-type projection screen for in-vehicle mirrors.

[0008] It is being considered to equip automotive mirrors (especially those mounted on the exterior of the vehicle, such as side mirrors) with sensors (e.g., LiDAR sensors) to measure the distance to surrounding vehicles. When constructing such an automotive mirror equipped with a sensor using the aforementioned mirror-type projection screen, it is necessary to ensure that the sensor's function is not impaired. In particular, since the sensor will be located behind the mirror-type projection screen, it is required that the mirror-type projection screen transmits infrared light and other light emitted or received by the sensor without obstruction.

[0009] This invention has been made in view of the above circumstances, and aims to provide a mirror-type projection screen that can fully perform its function as a mirror while also being capable of displaying good images.

[0010] Furthermore, the present invention aims to provide a mirror-type projection screen that fully functions as a mirror while enabling good image display and without impairing the functionality of sensors such as LiDAR sensors. [Means for solving the problem]

[0011] To achieve the above objective, the present invention first provides a mirror-type projection screen, wherein the mirror-type projection screen comprises a half-mirror film and a transparent screen layer laminated on one side of the half-mirror film, and the transparent screen layer is characterized in that light-diffusing fine particles are dispersed in a matrix component (Invention 1).

[0012] In the above invention (Invention 1), it is preferable that the half-mirror film is a metal-deposited film in which metal is deposited on at least one side of a transparent substrate (Invention 2).

[0013] In the above invention (Invention 1), it is preferable that the half-mirror film does not have a metal vapor-deposited film (Invention 3).

[0014] In the above invention (Invention 3), it is preferable that the half-mirror film is a fine laminated film having a laminated structure in which two or more resin layers made of different resins are alternately laminated in the thickness direction (Invention 4).

[0015] In the above inventions (Inventions 1 to 4), the transparent screen layer is preferably an adhesive layer in which the light-diffusing fine particles are dispersed in an adhesive (Invention 5).

[0016] In the above inventions (Inventions 1 to 4), the transparent screen layer is preferably a hard coat layer formed from a hard coat layer composition containing the light-diffusing fine particles (Invention 6).

[0017] In the above inventions (Inventions 1 to 6), it is preferable that the haze value of the mirror-type projection screen is 1% or more and 60% or less (Invention 7).

[0018] In the above inventions (Inventions 1 to 7), it is preferable that the mirror-type projection screen includes a light-transmissive member laminated on at least one of the surface on the half-mirror film side and the surface on the transparent screen layer side (Invention 8).

[0019] In the above inventions (Inventions 1, 3 or 4), it is preferably for constituting an in-vehicle mirror attached outside the vehicle (Invention 9).

Advantages of the Invention

[0020] The mirror-type projection screen according to the present invention can display good images while fully exhibiting the function as a mirror.

[0021] Also, when the half-mirror film of the mirror-type projection screen according to the present invention does not have a metal vapor deposition film, it can display good images while fully exhibiting the function as a mirror, and further does not impair the functions of sensors such as LiDAR sensors.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described. The mirror-type projection screen according to an embodiment of the present invention includes a half-mirror film and a transparent screen layer laminated on one side of the half-mirror film. And the transparent screen layer is formed by dispersing light-diffusing fine particles in a matrix component.

[0023] The mirror-type projection screen according to this embodiment, by being equipped with the half-mirror film, can function as a mirror when viewed from the side with the half-mirror film (hereinafter sometimes referred to as the "viewing surface"). On the other hand, because the mirror-type projection screen is equipped with a transparent screen layer in which the light-diffusing fine particles described above are dispersed, it can display an image (including video) projected from a projector placed on the side with the transparent screen layer (hereinafter sometimes referred to as the "back surface"), and the viewer can view the image from the viewing surface side. Furthermore, the mirror-type projection screen according to this embodiment can also effectively conceal the projector placed on the back surface, making it difficult for the viewer to see the projector.

[0024] Based on the above, the mirror-type projection screen according to this embodiment can be used as a mirror and can also be used effectively as a screen for displaying images.

[0025] Furthermore, in the mirror-type projection screen according to this embodiment, it is also preferable that the half-mirror film does not have a metal vapor-deposited film. In this case, the mirror-type projection screen according to this embodiment can transmit light (especially infrared light) used by sensors such as LiDAR sensors well because the half-mirror film does not have a metal vapor-deposited film. As a result, the sensor provided on the back surface of the mirror-type projection screen can fully perform its function. The mirror-type projection screen can be used as a mirror, can be used well as a screen for displaying images, and can also constitute an in-vehicle mirror that allows sensors such as LiDAR sensors to function well.

[0026] 1. Half-mirror film The above-mentioned half-mirror film is not particularly limited as long as it can perform its function as a half-mirror. Preferred examples of half-mirror films include a metal-deposited film in which metal is deposited on at least one side of a transparent substrate, and a fine laminated film having a laminated structure in which two or more resin layers made of different resins are alternately laminated in the thickness direction. The metal-deposited film and the fine laminated film will be described below.

[0027] (1) Metal vapor-deposited film As described above, a metal-deposited film is made by depositing metal onto at least one side of a transparent substrate.

[0028] The transparent substrate described above is not particularly limited as long as it has a predetermined light transmittance and allows for metal deposition, but it is preferably a resin film from the viewpoint of ease of handling and other factors. Examples of such resin films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin films such as polyethylene films and polypropylene films; cellophane; diacetylcellulose films; triacetylcellulose films; acetylcellulose butyrate films; polyvinyl chloride films; polyvinylidene chloride films; polyvinyl alcohol films; ethylene-vinyl acetate copolymer films; polystyrene films; polycarbonate films; polymethylpentene films; polysulfone films; polyetheretherketone films; polyethersulfone films; polyetherimide films; fluororesin films; polyamide films; acrylic resin films; polyurethane resin films; norbornene-based polymer films; cyclic olefin-based polymer films; cyclic conjugated diene-based polymer films; vinyl alicyclic hydrocarbon polymer films; and other plastic films or laminates thereof. Among these, polyethylene terephthalate film is preferred from the viewpoint of transparency and mechanical strength.

[0029] The thickness of the transparent substrate is preferably 5 to 300 μm, particularly preferably 10 to 200 μm, and even more preferably 15 to 100 μm. Having the transparent substrate thickness within this range facilitates the performance of the half-mirror and improves handling.

[0030] The metal deposited onto the transparent substrate is not particularly limited, and any metal commonly used in the manufacture of half-mirror films can be used. Examples include aluminum, aluminum alloys, nickel, and chromium. Among these, aluminum is preferred because it easily exhibits half-mirror performance.

[0031] The thickness of the deposited metal film on the transparent substrate is preferably 10 to 1000 nm, and particularly preferably 20 to 500 nm. Having the deposited film thickness within this range makes it possible to achieve a good balance between the reflectivity necessary for mirror function and the light transmittance necessary to allow the projected image from the projector to be visible from the viewing surface.

[0032] (2) Microlaminated film As mentioned above, a micro-laminated film is constructed by alternately laminating two or more resin layers, each composed of a different resin, in the thickness direction. Due to this laminated structure, the surface of the micro-laminated film functions as a mirror, exhibiting a predetermined level of light reflectivity. At the same time, the micro-laminated film also possesses a predetermined level of light transmittance. As a result, the micro-laminated film exhibits excellent half-mirror properties.

[0033] The fine laminated film is preferably made by alternately laminating multiple layers of two resin layers A and resin layer B with different refractive indices, and more preferably by alternately laminating 50 or more layers of two resin layers A and resin layer B with different refractive indices. The thickness of each layer is preferably 30 to 500 nm, more preferably 50 to 450 nm, and even more preferably 100 to 400 nm.

[0034] The total number of layers in the fine laminated film is preferably 200 or more, particularly preferably 400 or more, and even more preferably 600 or more. Having a total of 200 or more layers makes it easier to achieve excellent half-mirror properties. On the other hand, there is no particular upper limit to the total number of layers; for example, it is preferably 1500 or less.

[0035] A preferred example of the resin a constituting resin layer A and the resin b constituting resin layer B is a combination in which resin a is polyethylene terephthalate or polyethylene naphthalate and resin b is a polyester containing spiroglycol. Here, a polyester containing spiroglycol refers to a polyester copolymerized with spiroglycol, or a polyester blended with another homopolyester. Because the glass transition temperature difference between the polyester containing spiroglycol and polyethylene terephthalate or polyethylene naphthalate is small, it is less likely to be overstretched during molding and less likely to delaminate between layers.

[0036] A more preferred example of the combination of resin a and resin b is a combination in which resin a is polyethylene terephthalate or polyethylene naphthalate, and resin b is a polyester containing spiroglycol and cyclohexanedicarboxylic acid. Here, a polyester containing spiroglycol and cyclohexanedicarboxylic acid refers to a polyester copolymerized with spiroglycol and cyclohexanedicarboxylic acid (or an ester derivative of cyclohexanedicarboxylic acid), or a polyester blended with another homopolyester. When resin b is a polyester containing spiroglycol and cyclohexanedicarboxylic acid, the in-plane refractive index difference with polyethylene terephthalate or polyethylene naphthalate becomes large, making it easier to obtain a high reflectivity. In addition, because the glass transition temperature difference with polyethylene terephthalate or polyethylene naphthalate is small, over-stretching during molding is less likely to occur, and delamination is also less likely to occur.

[0037] Another preferred example of the combination of resin a and resin b is a combination in which resin a is polyethylene terephthalate or polyethylene naphthalate and resin b is a polyester containing cyclohexanedimethanol. Here, a polyester containing cyclohexanedimethanol refers to a polyester copolymerized with cyclohexanedimethanol, or a polyester blended with another homopolyester. Because the glass transition temperature difference between the polyester containing cyclohexanedimethanol and polyethylene terephthalate or polyethylene naphthalate is small, it is less likely to be overstretched during molding and less likely to delaminate.

[0038] As the fine laminated film, commercially available products may be used, and preferred examples include the "PICASUS" series from Toray Industries, Inc. and the "MLF Film" series from Teijin DuPont Films Ltd.

[0039] The thickness of the fine laminated film is preferably 20 to 750 μm, more preferably 30 to 500 μm, particularly preferably 45 to 300 μm, even more preferably 50 to 200 μm, and most preferably 60 to 150 μm. This makes it easier to achieve a good balance between the reflectivity necessary for it to function as a mirror and the light transmittance necessary to make the image projected from the projector visible from the viewing surface.

[0040] (3) Physical properties, etc. In the half-mirror film of this embodiment, the total light transmittance is preferably 50% or less, more preferably 45% or less, particularly preferably 35% or less, even more preferably 25% or less, and most preferably 15% or less. A total light transmittance of 50% or less makes it easier to effectively perform the function of a half-mirror. The lower limit of the total light transmittance is preferably 1% or more, particularly preferably 2% or more, and even more preferably 3% or more, from the viewpoint of ensuring the concealment of the projector body, etc. The detailed measurement method of the total light transmittance is as described in the test examples below.

[0041] In the half-mirror film of this embodiment, the haze value is preferably 0 to 20%, more preferably 0.1 to 12%, particularly preferably 0.5 to 8%, and even more preferably 1 to 5%. This makes it easier to adjust the total light transmittance to the aforementioned range. The detailed method for measuring the haze value is as described in the test examples below.

[0042] In the half-mirror film of this embodiment, the 20° gloss measured on the mirror surface (in the case of a metal vapor-deposited film, the vapor-deposited film side) is preferably 300 to 3000%, more preferably 600 to 2600%, particularly preferably 900 to 2200%, even more preferably 1100 to 2000%, and most preferably 1500 to 1800%. This makes it easier for the half-mirror film to perform its function as a mirror well, and also ensures that the color is not problematic.

[0043] In the half-mirror film of this embodiment, the 45° gloss measured on the mirror surface is preferably 200-2600%, more preferably 400-2300%, particularly preferably 600-2000%, and even more preferably 900-1800%. Furthermore, if the half-mirror film is a metal vapor-deposited film, the 45° gloss is most preferably 1300-1700%. Also, if the half-mirror film is a fine laminated film, the 45° gloss is most preferably 1100-1300%. This makes it easier for the half-mirror film to perform its function as a mirror well, and the color is also satisfactory.

[0044] In the half-mirror film of this embodiment, the 60° gloss measured on the mirror surface is preferably 100-2000%, more preferably 300-1500%, particularly preferably 500-1200%, and even more preferably 650-900%. Furthermore, if the half-mirror film is a metal vapor-deposited film, the 60° gloss is most preferably 780-820%. Also, if the half-mirror film is a fine laminated film, the 60° gloss is most preferably 700-790%. This makes it easier for the half-mirror film to perform its function as a mirror well, and the color is also satisfactory.

[0045] In the half-mirror film of this embodiment, the 85° gloss measured on the mirror surface is preferably 10-200%, more preferably 60-175%, particularly preferably 100-160%, even more preferably 115-150%, and most preferably 125-140%. This makes it easier for the half-mirror film to perform its function as a mirror well, and also ensures that the color is not problematic.

[0046] By satisfying the gloss requirements at each angle, the mirror is more likely to function well when viewed from any angle.

[0047] The detailed measurement methods for the gross at each of the above angles are as described in the test examples below.

[0048] 2. Transparent screen layer The transparent screen layer in this embodiment is not particularly limited, as long as it consists of light-diffusing fine particles dispersed in a matrix component. Examples of preferred transparent screen layers include an adhesive layer in which light-diffusing fine particles are dispersed in an adhesive, and a hard coat layer formed from a hard coat layer composition containing light-diffusing fine particles. When the transparent screen layer is an adhesive layer, it can be well bonded to the adherend such as the half-mirror film described above, making it possible to provide a mirror-type projection screen with a simple configuration. On the other hand, when the transparent screen layer is a hard coat layer, it is possible to provide a mirror-type projection screen with excellent scratch resistance and durability against external forces. The adhesive layer and the hard coat layer will be described below.

[0049] (1) Adhesive layer The adhesive that constitutes the above adhesive layer as a matrix component is not particularly limited as long as it is possible to disperse light-diffusing fine particles. Preferably, the adhesive layer has a predetermined light transmittance (especially near-infrared transmittance when the half-mirror film does not have a metal vapor-deposited film), and preferably can exhibit a desired adhesive strength. Examples of adhesives that constitute the above adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. Among these, it is preferable to use an acrylic adhesive because it is easy to form a desired transparent screen layer and easy to exhibit a desired adhesive strength.

[0050] When the adhesive layer described above is composed of an acrylic adhesive, it is preferable that the adhesive layer is formed from an adhesive composition containing a (meth)acrylic acid ester polymer and light-diffusing fine particles, and more preferably from an adhesive composition containing a (meth)acrylic acid ester polymer, a crosslinking agent, and light-diffusing fine particles. An adhesive layer formed using such an adhesive composition has a structure in which light-diffusing fine particles are dispersed within a matrix component consisting of a (meth)acrylic acid ester polymer, or a crosslinked product in which a (meth)acrylic acid ester polymer is crosslinked with a crosslinking agent. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "polymer" is also included in the concept of "polymer".

[0051] In this embodiment, the (meth)acrylic acid ester polymer preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer, which has a reactive group in its molecule that reacts with the crosslinking agent. The reactive group derived from this reactive group-containing monomer reacts with the crosslinking agent, resulting in the formation of a good crosslinked structure (three-dimensional network structure). Furthermore, the dispersibility of the light-diffusing fine particles, which will be described later, tends to be good, making it easier to obtain the desired transparent screen layer.

[0052] Preferred examples of the reactive group-containing monomers include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers). Among these, hydroxyl group-containing monomers or carboxyl group-containing monomers are preferred from the viewpoint of dispersibility of light-diffusing fine particles and excellent reactivity with crosslinking agents.

[0053] Examples of monomers containing hydroxyl groups include hydroxyalkyl esters of (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, hydroxyalkyl esters of (meth)acrylates having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth)acrylate polymer with the crosslinking agent, copolymerizability with other monomers, and dispersibility of light-diffusing fine particles. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

[0054] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoint of the reactivity of the carboxyl group in the resulting (meth)acrylic acid ester polymer with the crosslinking agent, copolymerizability with other monomers, and dispersibility of light-diffusing fine particles. These may be used alone or in combination of two or more.

[0055] Examples of amino group-containing monomers include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used individually or in combination of two or more. Note that nitrogen atom-containing monomers, as described later, are excluded from this list of amino group-containing monomers.

[0056] The (meth)acrylic acid ester polymer preferably contains reactive group-containing monomers in the range of 1 to 40% by mass, particularly preferably in the range of 10 to 35% by mass, and even more preferably in the range of 20 to 30% by mass, as monomer units constituting the polymer. This facilitates the formation of a good crosslinking structure in the resulting adhesive and tends to improve the dispersibility of the light-diffusing fine particles described later, making it easier to obtain the desired transparent screen layer.

[0057] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, the (meth)acrylic acid ester polymer preferably contains reactive group-containing monomers in the range of 0.1 to 40% by mass as monomer units constituting the polymer, particularly preferably in the range of 10 to 35% by mass, and even more preferably in the range of 20 to 30% by mass. This makes it easier to form a good cross-linked structure in the resulting adhesive, and tends to improve the dispersibility of the light-diffusing fine particles described later, making it easier to obtain the desired transparent screen layer.

[0058] The (meth)acrylic acid ester polymer may also preferably contain an alkyl (meth)acrylic acid ester as a monomer unit constituting the polymer. This makes it easier to exhibit good tackiness and provides excellent adhesion to half-mirror films. The alkyl group of the alkyl (meth)acrylic acid ester may be linear or branched.

[0059] From the viewpoint of adhesiveness, alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group are preferred. Examples of alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. In particular, from the viewpoint of further improving adhesiveness, methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate are especially preferred, and n-butyl acrylate, 2-ethylhexyl acrylate, or methyl methacrylate are even more preferred. These may be used individually or in combination of two or more.

[0060] The (meth)acrylic acid ester polymer preferably contains alkyl (meth)acrylate as a monomer unit in the range of 60 to 99% by mass, particularly preferably in the range of 65 to 90% by mass, and even more preferably in the range of 70 to 80% by mass. This makes the (meth)acrylic acid ester polymer more likely to exhibit good tackiness and excellent adhesion to half-mirror films. Furthermore, it becomes easier to introduce other monomers, such as monomers containing reactive functional groups, into the (meth)acrylic acid ester polymer in desired amounts. Moreover, the dispersibility of light-diffusing fine particles, described later, tends to be good, making it easier to obtain the desired transparent screen layer, and combined with the adhesion to half-mirror films, the desired mirror-type projection screen can be obtained.

[0061] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, the (meth)acrylic acid ester polymer preferably contains alkyl (meth)acrylate as monomer units in the range of 60 to 99.9% by mass, particularly preferably in the range of 65 to 90% by mass, and even more preferably in the range of 70 to 80% by mass. This makes the (meth)acrylic acid ester polymer more likely to exhibit good tackiness and excellent adhesion to the half-mirror film. In addition, the upper limit of the alkyl (meth)acrylate content is as described above, making it easier to introduce other monomers, such as monomers containing reactive functional groups, into the (meth)acrylic acid ester polymer in the desired amount. Furthermore, the dispersibility of light-diffusing fine particles, which will be described later, tends to be good, making it easier to obtain the desired transparent screen layer, and combined with the adhesion to the half-mirror film, the desired mirror-type projection screen can be obtained.

[0062] (Meth)acrylic acid ester polymers may optionally contain other monomers as monomer units constituting the polymer. Examples of such monomers include monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers), unreactive nitrogen atom-containing monomers such as N-acryloylmorpholine and N-vinyl-2-pyrrolidone, alkoxyalkyl (meth)acrylate esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used individually or in combination of two or more.

[0063] The (meth)acrylic acid ester polymer is preferably a linear polymer. Being a linear polymer makes it easier for molecular chains to intertwine, which can be expected to improve cohesiveness and make it easier to achieve better high-temperature durability. In addition, it tends to have good dispersibility of light-diffusing fine particles, as described later, making it easier to obtain the desired transparent screen layer.

[0064] Furthermore, the (meth)acrylic acid ester polymer is preferably a solution polymer obtained by solution polymerization. Being a solution polymer makes it easier to obtain a high molecular weight polymer, which can be expected to improve cohesive strength and make it easier to achieve better high-temperature durability. In addition, it tends to have good dispersibility of the light-diffusing fine particles described later, making it easier to obtain the desired transparent screen layer.

[0065] The polymerization mode of the (meth)acrylic acid ester polymer may be a random copolymer or a block copolymer.

[0066] The weight-average molecular weight of the (meth)acrylic acid ester polymer is preferably 100,000 to 3,000,000, more preferably 200,000 to 2,000,000, particularly preferably 300,000 to 1,000,000, and even more preferably 400,000 to 700,000. This results in good adhesion and excellent bonding properties with half-mirror films. Furthermore, it tends to improve the dispersibility of light-diffusing fine particles, as described later, making it easier to obtain the desired transparent screen layer. Note that the weight-average molecular weight in this specification is the value on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0067] In the adhesive composition, one (meth)acrylic acid ester polymer may be used alone, or two or more polymers may be used in combination.

[0068] The above-mentioned crosslinking agent can be any agent that reacts with the reactive functional groups of the (meth)acrylic acid ester polymer. Examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. The crosslinking agent can be used individually or in combination of two or more types.

[0069] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret and isocyanurate forms, as well as adducts which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

[0070] The amount of crosslinking agent used is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, particularly preferably 0.1 to 3 parts by mass, and even more preferably 0.8 to 2 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer. This facilitates the formation of a good crosslinked structure in the resulting adhesive and tends to improve the dispersibility of the light-diffusing fine particles described later, making it easier to obtain the desired transparent screen layer.

[0071] The above-mentioned light-diffusing nanoparticles are not limited as long as they can impart a predetermined light-diffusing property to the transparent screen layer, but inorganic nanoparticles are preferably used.

[0072] Examples of inorganic fine particles include metal oxides such as silica, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide; and metal fluorides such as magnesium fluoride and sodium fluoride. Among these, metal oxides are preferred from the viewpoint of haze generation and dispersibility, and titanium oxide or zinc oxide are particularly preferred. The surface of the inorganic fine particles may be chemically modified with organic compounds or the like.

[0073] The inorganic nanoparticles may have any shape, such as a perfect sphere or an irregular shape, but an irregular shape is preferable from the viewpoint of efficiently exhibiting light diffusion properties with a small amount.

[0074] In this embodiment, the light-diffusing fine particles are preferably so-called nanoparticles. Specifically, the average particle size of the light-diffusing fine particles is preferably 10 to 1000 nm, more preferably 30 to 700 nm, particularly preferably 50 to 500 nm, and even more preferably 100 to 350 nm. By having the average particle size of the light-diffusing fine particles within the above range, it becomes easier to achieve the desired light-diffusing properties and obtain a transparent screen layer that exhibits the desired optical properties. The average particle size of the light-diffusing fine particles is measured by laser diffraction and scattering.

[0075] In this embodiment, the refractive index of the light-diffusing microparticles is preferably 1.8 to 3.0, more preferably 1.9 to 2.6, and particularly preferably 2.0 to 2.3. Having the refractive index of the light-diffusing microparticles within this range makes it easier to achieve the desired light diffusion properties and obtain a transparent screen layer exhibiting the desired optical properties. The refractive index of the light-diffusing microparticles can be measured, for example, by the following method: Placing microparticles on a glass slide, dropping a refractive index standard solution onto the microparticles, and covering with a coverslip to prepare a sample. Observing the sample under a microscope, the refractive index of the refractive index standard solution at which the outline of the microparticles becomes least visible is defined as the refractive index of the microparticles.

[0076] The content of light-diffusing fine particles in the adhesive composition is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 8 parts by mass, particularly preferably 0.1 to 6 parts by mass, even more preferably 0.2 to 4 parts by mass, and most preferably 0.8 to 3 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer. This makes it easier to achieve the desired light-diffusing properties and to obtain a transparent screen layer that exhibits the desired optical properties.

[0077] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, the content of light-diffusing fine particles in the adhesive composition is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 8 parts by mass, particularly preferably 0.1 to 6 parts by mass, and even more preferably 0.2 to 6 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer. This makes it easier to achieve the desired light-diffusing properties and to obtain a transparent screen layer that exhibits the desired optical properties.

[0078] In addition to (meth)acrylic acid ester polymers, crosslinking agents, and light-diffusing fine particles, the adhesive composition may optionally contain various commonly used additives, such as refractive index modifiers, antistatic agents, tackifiers, silane coupling agents, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, photocuring agents, and photopolymerization initiators.

[0079] When the transparent screen layer is an adhesive layer, the thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 15 μm or more, and even more preferably 20 μm or more, from the viewpoint of easily achieving the desired light diffusion and adhesiveness. Furthermore, the thickness of the adhesive layer is preferably 1000 μm or less, more preferably 500 μm or less, particularly preferably 100 μm or less, even more preferably 50 μm or less, and most preferably 30 μm or less, from the viewpoint of the smoothness of the adhesive layer surface and ease of handling when bonding with an adherend such as a half-mirror film.

[0080] (2) Hard coat layer The hard coat layer described above is not particularly limited as long as it is formed from a hard coat layer composition containing light-diffusing fine particles. Preferably, the hard coat layer has a predetermined light transmittance and a desired hardness. Preferably, the hard coat layer composition contains an active energy ray curable component together with the light-diffusing fine particles. The hard coat layer may also be formed on other components constituting the mirror-type projection screen according to this embodiment (such as a half-mirror film or a light-transmitting member described later).

[0081] The above-mentioned active energy ray curable component is preferably one that hardens upon irradiation with active energy rays and exhibits a predetermined hardness. Specific examples include polyfunctional (meth)acrylate monomers, (meth)acrylate prepolymers, and active energy ray curable polymers. Among these, polyfunctional (meth)acrylate monomers and / or (meth)acrylate prepolymers are preferred from the viewpoint of having excellent dispersibility of light-diffusing fine particles. The polyfunctional (meth)acrylate monomers and (meth)acrylate prepolymers may be used individually or in combination.

[0082] Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. Examples of polyfunctional (meth)acrylates include acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. These may be used individually or in combination of two or more. Among the above, those with 3 to 6 functional groups are preferred, and those with 4 to 6 are particularly preferred, from the viewpoint of excellent dispersibility of light-diffusing fine particles and scratch resistance.

[0083] On the other hand, examples of (meth)acrylate-based prepolymers include polyester acrylate-based, epoxy acrylate-based, urethane acrylate-based, and polyol acrylate-based prepolymers. Among these, urethane acrylate-based prepolymers are preferred from the viewpoint of having excellent dispersibility of light-diffusing fine particles and suppressing curling, and polyfunctional urethane acrylate-based prepolymers are particularly preferred.

[0084] Polyester acrylate prepolymers can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth)acrylic acid.

[0085] Epoxyacrylate prepolymers can be obtained, for example, by reacting (meth)acrylic acid with the oxirane ring of a relatively low molecular weight bisphenol-type epoxy resin or novolac-type epoxy resin to esterify it.

[0086] Urethane acrylate-based prepolymers can be obtained, for example, by esterifying polyurethane oligomers, which are obtained by the reaction of polyether polyols or polyester polyols with polyisocyanates, with (meth)acrylic acid.

[0087] Polyol acrylate-based prepolymers can be obtained, for example, by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

[0088] The above prepolymers may be used individually or in combination of two or more.

[0089] When a polyfunctional (meth)acrylate monomer and a (meth)acrylate prepolymer are used in combination, their mass ratio is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, particularly preferably 25:75 to 75:25, and even more preferably 30:70 to 70:30. This tends to result in good hardness and scratch resistance, as well as good dispersibility of light-diffusing fine particles, making it easier to obtain the desired transparent screen layer.

[0090] Examples of light-diffusing fine particles contained in the hard coat layer composition include those exemplified above as light-diffusing fine particles dispersed in the adhesive layer.

[0091] The content of light-diffusing fine particles in the hard coat layer composition is preferably 0.001 to 50 parts by mass, more preferably 0.01 to 40 parts by mass, particularly preferably 0.1 to 30 parts by mass, and even more preferably 1 to 20 parts by mass, per 100 parts by mass of the active energy ray curable component. This makes it easier to achieve the desired light diffusion and to obtain a transparent screen layer that exhibits the desired optical properties.

[0092] When ultraviolet light is used as the active energy ray for curing the active energy ray-curable component, the above-mentioned hard coat layer composition preferably contains a photopolymerization initiator. By including a photopolymerization initiator, the active energy ray-curable component can be polymerized efficiently, and the polymerization curing time and the amount of ultraviolet irradiation can be reduced.

[0093] Examples of such photopolymerization initiators include bensoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzoin Examples include non, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, etc. These may be used individually or in combination of two or more.

[0094] The content of the photopolymerization initiator in the hard coat layer composition is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the active energy ray curable component. This makes it easier to obtain a transparent screen layer that exhibits good hardness and scratch resistance.

[0095] In addition to the components listed above, the hard coat layer composition may also contain various additives. Examples of such additives include leveling agents, anti-glare agents, (near)infrared absorbers, ultraviolet absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, anti-aging agents, thermal polymerization inhibitors, colorants, surfactants, preservative stabilizers, plasticizers, lubricants, defoamers, and wettability improvers.

[0096] When the transparent screen layer is a hard coat layer, the thickness of the hard coat layer is preferably 1 to 50 μm, more preferably 1.5 to 20 μm, particularly preferably 2 to 10 μm, and even more preferably 3 to 8 μm. Having the hard coat layer thickness within this range makes it easier to achieve the desired light diffusion properties, obtain a predetermined surface hardness, and provide excellent scratch resistance.

[0097] (3) Physical properties, etc. In this embodiment, the transparent screen layer preferably has a total light transmittance of 70% or more, more preferably 75% or more, particularly preferably 80% or more, and even more preferably 82% or more. A total light transmittance of 70% or more makes it easier to display images projected from a projector clearly. The upper limit of the total light transmittance is usually 100%, but when combined with a half-mirror film, from the viewpoint of easily displaying images projected from a projector while also functioning as a mirror, it is preferably 95% or less, more preferably 90% or less, particularly preferably 89% or less, even more preferably 88% or less, and most preferably 87% or less. A detailed method for measuring the total light transmittance is described in the test examples below.

[0098] In this embodiment, the haze value of the transparent screen layer is preferably 1 to 60%, more preferably 4 to 50%, particularly preferably 8 to 40%, and even more preferably 12 to 35%. A haze value within this range makes it easier to display images projected from a projector clearly. In particular, when combined with a half-mirror film, it makes it easier to display images projected from a projector clearly while simultaneously maintaining the function of a mirror. The detailed method for measuring the haze value is described in the test examples below.

[0099] 3. Other components The mirror-type projection screen according to this embodiment may include other components besides the half-mirror film and transparent screen layer described above.

[0100] For example, the mirror-type projection screen according to this embodiment may further include a light-transmitting member. This light-transmitting member may be laminated on at least one of the surfaces of the mirror-type projection screen: the half-mirror film side and the transparent screen layer side.

[0101] The light-transmitting member may be a transparent, rigid body such as a glass plate or a plastic plate, or a flexible transparent body such as a plastic film.

[0102] When the light-transmitting member is a transparent rigid body, the thickness of the light-transmitting member is preferably 0.3 to 1000 mm, more preferably 0.6 to 500 mm, particularly preferably 0.9 to 100 mm, and even more preferably 1 to 3 mm. By having such a light-transmitting member, the mirror-type projection screen according to this embodiment will have high durability while possessing the desired light diffusion and mirror properties, and will exhibit a suitable user experience. In this specification, "rigid body" refers to a member whose structure can be bent at an angle of less than 90° without irreversible deformation. This angle is preferably less than 60°, more preferably less than 45°, particularly preferably less than 10°, and even more preferably less than 5°. The bendable angle (bending angle) refers to the angle at which the rigid body rises from the horizontal surface when it is placed on a horizontal surface, one end is fixed, and the opposite end is raised. The rigid body may consist of a single layer or a single member, or it may consist of multiple layers or multiple members.

[0103] When the light-transmitting member is a flexible transparent material, the thickness of the light-transmitting member is preferably 10 to 300 μm, and more preferably 20 to 200 μm. By having such a light-transmitting member, the mirror-type projection screen according to this embodiment is highly flexible while possessing the desired light diffusion and mirror properties, and can be used on curved surfaces and the like.

[0104] Furthermore, if the transparent screen layer is the aforementioned adhesive layer, a permeable member may be laminated on the adhesive layer to protect it. In this case, the permeable member is preferably a plastic film such as polyethylene terephthalate film.

[0105] Furthermore, if the adhesion between the components constituting the mirror-type projection screen is poor, an adhesive layer (different from the transparent screen layer) may be provided to reinforce the bonding of those components.

[0106] 4. Physical properties of mirror-type projection screens In the mirror-type projection screen according to this embodiment, the total light transmittance is preferably 1% or more and 50% or less. Having the total light transmittance of the mirror-type projection screen within this range makes it easier to effectively perform both its function as a mirror and its function as a screen for displaying images. From this viewpoint, the total light transmittance is preferably 1.5 to 42%, more preferably 2 to 34%, particularly preferably 2.5 to 26%, even more preferably 3 to 18%, and most preferably 3.5 to 8%. Having the total light transmittance of the mirror-type projection screen within this range makes it easier to effectively perform both its function as a mirror and its function as a screen for displaying images. The detailed measurement method for the total light transmittance is described in the test examples below.

[0107] In the mirror-type projection screen according to this embodiment, the haze value is preferably 1% or more and 60% or less. A haze value within this range allows the mirror-type projection screen to effectively perform both its function as a mirror and its function as a screen for displaying images. From this viewpoint, the haze value is preferably 5-50%, more preferably 10-45%, particularly preferably 13-41%, and even more preferably 16-37%. The detailed measurement method for the haze value is described in the test examples below.

[0108] In the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting the function of a mirror, the 20° gloss measured on the mirror surface is preferably 300 to 3000%, more preferably 600 to 2600%, and particularly preferably 800 to 2200%. From the viewpoint of the color when viewed, it is preferably 1000 to 1900%, even more preferably 1300 to 1800%, and most preferably 1500 to 1700%. The above-mentioned mirror surface refers to the surface composed of the mirror surface of the half-mirror film. If a transparent screen layer or a light-transmitting member is laminated on the mirror surface of the half-mirror film, the above-mentioned 20° gloss shall be measured on the mirror surface through them (the same applies to the gloss of the mirror-type projection screen below).

[0109] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, in the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting good mirror function, the 20° gloss measured on the mirror surface is preferably 300 to 3000%, more preferably 600 to 2600%, particularly preferably 800 to 2200%, and from the viewpoint of color when viewed, it is preferably 1000 to 1900%, even more preferably 1200 to 1700%, and among these preferably 1300 to 1500%.

[0110] In the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting the function of a mirror well, the 45° gloss measured on the mirror surface is preferably 200 to 2600%, more preferably 500 to 2300%, and particularly preferably 700 to 2000%. From the viewpoint of the color when viewed, it is preferably 900 to 1900%, even more preferably 1100 to 1800%, and among these, preferably 1300 to 1700%.

[0111] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, in the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting good mirror function, the 45° gloss measured on the mirror surface is preferably 200 to 2600%, more preferably 500 to 2300%, particularly preferably 700 to 2000%, and from the viewpoint of color perception when viewed, it is preferably 900 to 1500%, even more preferably 1100 to 1400%, and among these, preferably 1200 to 1300%.

[0112] In the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting the function of a mirror well, the 60° gloss measured on the mirror surface is preferably 100 to 2000%, more preferably 300 to 1500%, and particularly preferably 400 to 1000%. From the viewpoint of the color when viewed, it is preferably 500 to 900%, even more preferably 650 to 860%, and among these, preferably 780 to 820%.

[0113] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, in the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting good mirror function, the 60° gloss measured on the mirror surface is preferably 100 to 2000%, more preferably 300 to 1500%, particularly preferably 400 to 1000%, and from the viewpoint of color perception when viewed, it is preferably 500 to 900%, even more preferably 600 to 800%, and most preferably 700 to 780%.

[0114] In the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting the function of a mirror well, the 85° gloss measured on the mirror surface is preferably 10 to 200%, more preferably 60 to 175%, particularly preferably 100 to 150%, and from the viewpoint of the color when viewed, it is preferably 110 to 145%, even more preferably 118 to 140%, and among these preferably 125 to 135%.

[0115] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, in the mirror-type projection screen according to this embodiment, from the viewpoint of easily exhibiting good mirror function, the 85° gloss measured on the mirror surface is preferably 10-200%, more preferably 60-175%, particularly preferably 100-150%, and from the viewpoint of color perception when viewed, preferably 110-142%, and even more preferably 118-138%.

[0116] By satisfying the gloss requirements at each angle, the mirror is more likely to function well when viewed from any angle.

[0117] The detailed measurement methods for the gross at each of the above angles are as described in the test examples below.

[0118] 5. Manufacturing method of a mirror-type projection screen The mirror-type projection screen according to this embodiment can be manufactured, for example, by appropriately laminating a pre-fabricated half-mirror film and a transparent screen layer, as well as other desired components.

[0119] If the transparent screen layer is an adhesive layer composed of the aforementioned acrylic adhesive, an example of a method for forming the adhesive layer is to prepare a coating solution containing the adhesive composition and, optionally, a solvent or dispersion medium. Then, the coating solution is applied to the release surface of the release sheet. Subsequently, the resulting coating film is dried to form the adhesive layer.

[0120] The above-mentioned coating liquid can be applied by known methods, such as bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, etc. The properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain components for forming the adhesive layer as a solute or as a dispersed phase. Furthermore, if an adhesive layer is formed on a release sheet, the release sheet may be peeled off as a process material, or it may protect the adhesive layer until it is attached to the substrate.

[0121] If the adhesive composition for forming the adhesive layer contains the aforementioned crosslinking agent, it is preferable to promote the crosslinking reaction between the polymer components in the coating film and the crosslinking agent by changing the drying conditions (temperature, time, etc.) or by separately providing a heat treatment, thereby forming a crosslinked structure with a desired density in the adhesive layer. Furthermore, in order to allow the above-mentioned crosslinking reaction to proceed sufficiently, after the completion of the transparent screen layer, curing may be performed, for example, by leaving it undisturbed for several days in an environment of 23°C and 50% relative humidity.

[0122] If the transparent screen layer is the hard coat layer described above, an example of a method for forming the hard coat layer is to prepare a coating solution containing a hard coat layer composition and, optionally, a solvent. This solution is then applied to other components constituting the mirror-type projection screen (half-mirror film, light-transmitting component, etc.) and dried to form the composition layer. The coating solution can be applied by conventional methods, such as bar coating, knife coating, Meyer bar coating, roll coating, blade coating, die coating, or gravure coating. Drying can be performed, for example, by heating at 40-180°C for about 30 seconds to 5 minutes.

[0123] Examples of the solvents mentioned above include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, butanol, and propylene glycol monomethyl ether, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve-based solvents such as ethyl cellosolve. Only one solvent may be used, or two or more solvents may be mixed. The concentration and viscosity of the coating solution are not particularly limited and can be selected appropriately depending on the situation, as long as they are within the range of coating.

[0124] Next, the composition layer is cured into a hard coat layer by irradiating it with an active energy ray. As the active energy ray, ultraviolet rays, electron beams, etc., can be used. Ultraviolet irradiation can be performed using a high-pressure mercury lamp, fusion H lamp, xenon lamp, etc., and the ultraviolet irradiation dose is 50-1000 mW / cm². 2 , light intensity 50~1000mJ / cm 2 A certain degree is preferable. On the other hand, electron beam irradiation can be performed using an electron beam accelerator, and the electron beam irradiation dose is preferably around 10 to 1000 krad.

[0125] 6. How to use a mirror-type projection screen The mirror-type projection screen according to this embodiment can be used as a projection screen that also functions as a mirror, and in particular, it can be used as a transparent projection screen that also functions as a mirror.

[0126] As described above, when used, the mirror surface (the metallic side) of the half-mirror film is positioned so that it becomes the viewing surface of the mirror-type projection screen according to this embodiment. The projector is positioned on the back side (the side opposite to the viewer) of the mirror-type projection screen according to this embodiment. In this case, from the viewpoint of avoiding excessive light being directed towards the viewer, it is preferable to position the projector so that it illuminates the projection screen from an oblique direction (particularly diagonally above or diagonally below the projection screen).

[0127] Furthermore, if the half-mirror film does not have a metal vapor-deposited film, the mirror-type projection screen according to this embodiment is preferably used as a projection screen for constructing an in-vehicle mirror, and is particularly preferably used as a transmissive projection screen for constructing an in-vehicle mirror.

[0128] The in-vehicle mirror configured with the mirror-type projection screen according to this embodiment may be installed inside the vehicle, like a rearview mirror. However, as mentioned above, the mirror-type projection screen according to this embodiment can sufficiently transmit light such as infrared light used in sensors such as LiDAR sensors, so it is preferable to configure it as an in-vehicle mirror on which such sensors are installed. Preferred examples of such in-vehicle mirrors include those installed outside the vehicle, and more specifically, side mirrors, fender mirrors, front under mirrors, rear under mirrors, etc.

[0129] Examples of the above-mentioned sensors include LiDAR sensors and RADAR sensors.

[0130] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0131] In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y." [Examples]

[0132] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0133] [Fabrication Example 1] (Formation of transparent screen layer A) An acrylic copolymer was obtained by polymerizing 62 parts by mass of n-butyl acrylate, 10 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate using a solution polymerization method. The weight-average molecular weight (Mw) of the acrylic copolymer was measured by the method described later and was found to be 500,000.

[0134] 100 parts by mass (based on solid content, the same applies hereafter) of the obtained acrylic polymer, 1.07 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent, and 0.25 parts by mass of zinc oxide fine particles (manufactured by Sakai Chemicals, product name "Fine Zinc Oxide", amorphous, average particle size: 300 nm, refractive index: 2.1) as light-diffusing fine particles were mixed in a solvent to obtain a coating solution of the adhesive composition (solid content concentration 25% by mass).

[0135] Next, a release sheet (Lintec Corporation, product name "SP-PET381031"), which has a silicone-based release agent layer formed on one side of a 38 μm thick polyethylene terephthalate film, was coated with the adhesive composition solution obtained as described above onto the release agent layer surface and dried by heating to form a 25 μm thick adhesive layer on the release sheet. This adhesive layer was then designated as the transparent screen layer A.

[0136] Here, the weight-average molecular weight (Mw) mentioned above is the weight-average molecular weight on a standard polystyrene basis, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> • Measuring device: Tosoh Corporation, HLC-8320 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Gel Super H-H TSK gel superHM-H TSK Gel Super H2000 • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0137] [Fabrication Example 2] (Formation of transparent screen layer B) The adhesive layer was formed in the same manner as in Fabrication Example 1, except that the content of light-diffusing fine particles was changed as shown in Table 1. This adhesive layer was then designated as the transparent screen layer B.

[0138] [Fabrication Example 3] (Formation of transparent screen layer C) The adhesive layer was formed in the same manner as in Fabrication Example 1, except that the content of light-diffusing fine particles was changed as shown in Table 1. This adhesive layer was then used as the transparent screen layer C.

[0139] [Fabrication Example 4] (Formation of transparent screen layer D) The adhesive layer was formed in the same manner as in Fabrication Example 1, except that the content of light-diffusing fine particles was changed as shown in Table 1. This adhesive layer was then designated as the transparent screen layer D.

[0140] [Preparation] (Half-mirror films A-E) Three types of aluminum-deposited films with different total light transmittances were prepared by vapor-depositing aluminum onto one side of polyethylene terephthalate (PET) film. In addition, two types of fine laminated films with different total light transmittances were prepared, resulting in five types of half-mirror films having the characteristics shown in Table 2. The optical properties, mirror properties, and screen properties shown in Table 2 can be determined by the methods described in Test Examples 2, 5, and 6 below. Half-mirror film A: An aluminum-deposited film (total light transmittance: 4.3%, thickness: 24 μm) made by depositing aluminum on one side of a polyethylene terephthalate (PET) film having the properties shown in Table 2. Half-mirror film B: An aluminum-deposited film (total light transmittance: 23.6%, thickness: 24 μm) made by depositing aluminum on one side of a polyethylene terephthalate (PET) film having the properties shown in Table 2. Half-mirror film C: An aluminum-deposited film (total light transmittance: 41.4%, thickness: 24 μm) made by depositing aluminum on one side of a polyethylene terephthalate (PET) film having the properties shown in Table 2. Half-mirror film D: A fine laminated film having a laminated structure in which two or more resin layers, each composed of different resins having the properties shown in Table 2, are alternately stacked in the thickness direction (manufactured by Toray Industries, Inc., product name "PICASUS G", total light transmittance: 32.2%, thickness: 128 μm). Half-mirror film E: A fine laminated film having a laminated structure in which two or more resin layers, each composed of different resins having the properties shown in Table 2, are alternately stacked in the thickness direction (manufactured by Toray Industries, Inc., product name "PICASUS CM", total light transmittance: 5.4%, thickness: 128 μm).

[0141] [Example 1] The side of the transparent screen layer A prepared in the above example 1 that is opposite to the release sheet was attached to the side of the half-mirror film A that has not been aluminum-deposited. The release sheet was peeled off from the resulting laminate, and the exposed surface of the transparent screen layer A was attached to one side of a 1.1 mm thick glass plate (soda-lime glass). This resulted in obtaining a mirror-type projection screen.

[0142] Furthermore, this mirror-type projection screen is designed so that the glass plate side is the back surface (the side on which the projector is placed), and the side opposite the glass plate is the viewing surface (the side on which the viewer is positioned). Therefore, in this mirror-type projection screen, the aluminum-coated surface of the half-mirror film A constitutes the viewing surface.

[0143] [Examples 2-6] A mirror-type projection screen was obtained in the same manner as in Example 1, except that the half-mirror film and the transparent screen layer were changed as shown in Table 3.

[0144] [Example 7] The side of the transparent screen layer B prepared in the above example 1 that was opposite to the release sheet was attached to one side of a polyethylene terephthalate (PET) film (Toray Industries, Ltd., product name "Lumirror #38-U48", thickness: 38 μm). The release sheet was peeled off from the resulting laminate, and the exposed surface of the transparent screen layer B was attached to the aluminum-deposited surface of the half-mirror film A described above. Furthermore, the side of the half-mirror film A that was not aluminum-deposited was attached to one side of a 1.1 mm thick glass plate (soda-lime glass) via a double-sided adhesive sheet (construction described later). This resulted in obtaining a mirror-type projection screen.

[0145] Furthermore, similar to Examples 1 to 6, the mirror-type projection screen is assumed to have the glass plate side as the back surface (the side on which the projector is placed) and the side opposite the glass plate as the viewing surface (the side on which the viewer is positioned). Therefore, in the mirror-type projection screen according to Example 7, one side of the PET film constitutes the viewing surface. However, since the aluminum-coated surface of the half-mirror film A faces the viewing surface, the viewer can perceive the aluminum-coated surface as a mirror surface.

[0146] Furthermore, the above-mentioned double-sided adhesive sheet is made by sequentially laminating a 25 μm thick acrylic adhesive layer, a 50 μm thick polyethylene terephthalate sheet (manufactured by Toyobo, product name "Cosmoshine A4160"), and a 15 μm thick silicone adhesive layer. When used as described above, the sheet was attached so that the side with the acrylic adhesive layer was in contact with the half-mirror film A, and the side with the silicone adhesive layer was in contact with the glass plate.

[0147] [Example 8] The side of the transparent screen layer D prepared in the above example 1 that was opposite to the release sheet was attached to one side of the half-mirror film D described above. The release sheet was peeled off from the resulting laminate, and the exposed surface of the transparent screen layer D was attached to one side of a 1.1 mm thick glass plate (soda-lime glass). This resulted in obtaining a mirror-type projection screen.

[0148] [Example 9] A mirror-type projection screen was obtained in the same manner as in Example 8, except that the half-mirror film was changed as shown in Table 3.

[0149] [Examples 10-12] A mirror-type projection screen was obtained in the same manner as in Example 8, except that the transparent screen layer was changed as shown in Table 3.

[0150] [Comparative Example 1] A glass plate (soda-lime glass) with a thickness of 1.1 mm was prepared and used as the screen for Comparative Example 1.

[0151] [Test Example 1] (Measurement of optical properties of a transparent screen layer) In manufacturing examples 1-4, the side of the transparent screen layer opposite to the release sheet was attached to one side of a 1.1 mm thick glass plate (soda-lime glass). After that, the release sheet was peeled off and removed to obtain a sample for measurement.

[0152] Then, after performing background measurements on the glass plate alone, the haze value (%) and total light transmittance (%) of the above-mentioned sample were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH 5000") in accordance with JIS K7361-1:1997. The results are shown in Table 1.

[0153] [Test Example 2] (Measurement of optical properties of half-mirror film) The half-mirror films A to E used in the example were attached to one side of a 1.1 mm thick glass plate (soda-lime glass) via a double-sided adhesive sheet (details of which are as described above). At this time, for half-mirror films A to C (aluminum-deposited films), the side opposite to the aluminum-deposited surface was attached so that it was in contact with the double-sided adhesive sheet. This resulted in obtaining a sample for measurement.

[0154] Then, after performing background measurements on the glass plate alone, the haze value (%) and total light transmittance (%) of the measurement sample were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH 5000") in accordance with JIS K7361-1:1997. At this time, the measurement was performed so that the measurement light was irradiated onto the half-mirror film side (i.e., the mirror surface) of the measurement sample. The measurement results are shown in Table 2.

[0155] Furthermore, for the half-mirror film side (i.e., the mirror surface) of the measurement samples obtained as described above, the gloss (%) was measured at incident angles of 20°, 45°, 60°, and 85° using a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "VG7000") in accordance with JIS Z8741:1997. The results are shown in Table 2.

[0156] [Test Example 3] (Measurement of optical properties of a mirror-type projection screen) For the mirror-type projection screen manufactured as an example and the screen manufactured as a comparative example, the haze value (%) and total light transmittance (%) were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH 5000") in accordance with JIS K7361-1:1997. For the mirror-type projection screen manufactured as an example, the measurement was performed so that the measurement light was irradiated from the side opposite to the glass plate. The results are shown in Table 3.

[0157] Furthermore, for the mirror-type projection screen manufactured as an example, the gloss (%) was measured on the side opposite to the glass plate, and for the screen manufactured as a comparative example, it was measured on any one side, in accordance with JIS Z8741:1997, using a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "VG7000"), at incident angles of 20°, 45°, 60°, and 85°. The results are shown in Table 3.

[0158] [Test Example 4] (Measurement of infrared transmittance of a mirror-type projection screen) The infrared transmittance of the mirror-type projection screens manufactured as Examples 4 and 8-12, as well as the screen manufactured as Comparative Example 1, was evaluated as follows. Note that all of the mirror-type projection screens in Examples 8-12 are equipped with a fine laminated film as the half-mirror film. The mirror-type projection screen of Example 4 was measured as a representative example of one equipped with an aluminum vapor-deposited film as the half-mirror film.

[0159] As examples and comparative examples, a camera lens from a digital camera-equipped mobile phone was placed 100 cm from the sample on the glass plate side (back side) of the manufactured screen sample. On the opposite side of the sample (viewing side), a television remote control was placed 100 cm from the sample. With the camera function of the digital camera-equipped mobile phone activated, any button on the television remote control was pressed to emit near-infrared light. Whether or not the near-infrared light emitted from the near-infrared light source could be received by the camera of the digital camera-equipped mobile phone was confirmed on the display screen of the digital camera-equipped mobile phone, and the detection performance of the near-infrared light was evaluated according to the following criteria. The evaluation results are shown in Table 3. ○: Near-infrared light image was confirmed. ×: The near-infrared image could not be confirmed.

[0160] [Test Example 5] (Evaluation of Miller characteristics) The mirror properties of the mirror-type projection screen manufactured as an example and the screen manufactured as a comparative example were evaluated as follows.

[0161] In a room under fluorescent lighting, an A4 sheet of paper with letters (A, B, C) and shapes (○, △, ×) was placed 100 cm from the glass plate side (back side) of the screen samples manufactured as examples and comparative examples. The font size of these letters and shapes was 144 points.

[0162] Next, with no image projected from the projector, the observer visually confirmed their own image on the sample surface (visual surface) and evaluated the reflectivity based on the following criteria. The color of the sample surface was also visually confirmed and evaluated based on the following criteria. Finally, text and figures used as a background were visually confirmed through the sample and evaluated the light transmittance based on the following criteria. The observer observed their own image, the color of that image, and the text and figures from a distance of 100 cm from the sample. The results are shown in Table 3.

[0163] <Reflectivity> ◎: The viewer's own image was clearly identified. ○: It was confirmed that the viewer's own image was not clear. △: The viewer's own image was difficult to identify. ×: The viewer's own image was not recognized.

[0164] <Color> A: No problematic discoloration, such as cloudiness, was observed. B: The color was generally cloudy and whitish. C: The overall color had a purplish tint.

[0165] <Light transparency> ◎: No text or figures were found. ○: Slightly discernible letters and shapes were present but difficult to recognize. △: The text and images were not clearly visible, but they were confirmed. ×: The letters and figures were clearly visible.

[0166] Furthermore, the mirror properties of half-mirror films A to E used in the examples were evaluated in the same manner as described above. Here, for half-mirror films A to C, which are aluminum-deposited films, the side without aluminum deposition was considered the back surface for evaluation. On the other hand, for half-mirror films D to E, which are micro-laminated films, any side was considered the back surface for evaluation. The results are shown in Table 2.

[0167] [Test Example 6] (Evaluation of Screen Characteristics) The screen characteristics of the mirror-type projection screen manufactured as an example and the screen manufactured as a comparative example were evaluated as follows.

[0168] In a darkroom with a ceiling height of 2.5m, a short-throw projector (Ricoh, product name "PJ WX4152N") was placed 20cm away from the glass plate side (back side) of the screen samples manufactured as examples and comparative examples. Then, a television idle image (a rectangular shape with various colors arranged in it) was projected onto the samples from the projector.

[0169] The projected image onto the sample was visually inspected from the opposite side of the sample from the projector (viewing side) and from 0° in front (directly in front of the projector), and the projection quality (Projection Quality A) was evaluated based on the following criteria. In addition, the ceiling was visually inspected, and the projection quality onto the ceiling (Projection Quality B) was evaluated based on the following criteria. Furthermore, it was visually checked whether the projector body and its light source were concealed through the sample, and the concealment quality was evaluated based on the following criteria. The inspector observed the projected image from a distance of 100 cm from the sample. The results are shown in Table 3.

[0170] <Projection A> ◎: The projected image was bright, and the boundaries of the color arrangement were clearly visible. ○: Although the viewer's own reflected image overlapped, the projected image was bright, and the boundaries of the color sequence were recognizable. △: The projected image overlapped with the viewer's own reflected image, making it difficult to perceive the boundaries of the color arrangement in the projected image. ×: Recognition of the projected image was difficult.

[0171] <Projection B> ◎: The projected image was difficult to recognize. ○: The projected image was recognized, but it was dark and difficult to discern the boundaries of the color sequence. △: The image was somewhat dark, but the boundaries of the color array in the projected image were recognized. ×: The projected image was bright, and the boundaries of the color array were clearly visible.

[0172] <Concealing properties> ◎: The projector unit and light source were not visible. ○: The projector itself was not visible, but the light source was slightly visible. △: The projector body and light source appeared blurred. ×: The projector unit and light source were clearly visible.

[0173] Furthermore, the screen properties of the transparent screen layers produced in Manufacturing Examples 1-4 and the half-mirror films A-E used in the examples were evaluated in the same manner as described above. Here, for the aluminum-deposited half-mirror films A-C, the side without aluminum deposition was considered the back surface for evaluation. On the other hand, for the transparent screen layers and the fine-laminated half-mirror films D-E, any side was considered the back surface for evaluation. The results are shown in Tables 1 and 2.

[0174] [Table 1]

[0175] [Table 2]

[0176] [Table 3]

[0177] As can be seen from Table 3, the mirror-type projection screens according to the embodiments exhibited excellent mirror properties and were able to fully function as mirrors, while also possessing excellent screen properties and being able to display images projected from a projector positioned behind them clearly. Furthermore, the mirror-type projection screens according to embodiments 10 to 12, which included a fine laminated film as the half-mirror film, were found to have excellent infrared transmittance and did not impair the function of sensors such as LiDAR sensors positioned behind them. [Industrial applicability]

[0178] The mirror-type projection screen of the present invention is suitably used as a mirror-type projection screen that serves as both a mirror and an image display screen. Furthermore, when the half-mirror film does not have a metal vapor-deposited film, the mirror-type projection screen of the present invention is suitably used as an in-vehicle mirror-type projection screen for an in-vehicle mirror equipped with a sensor such as a LiDAR sensor.

Claims

1. It is a mirror-type projection screen, The mirror-type projection screen comprises a half-mirror film without a metal vapor-deposited film and a transparent screen layer laminated on one side of the half-mirror film. The transparent screen layer is formed by dispersing light-diffusing fine particles in a matrix component. A mirror-type projection screen characterized by the following features.

2. The mirror-type projection screen according to claim 1, characterized in that the half-mirror film is a fine laminated film having a laminated structure in which two or more resin layers made of different resins are alternately laminated in the thickness direction.

3. The mirror-type projection screen according to claim 1 or 2, characterized in that the transparent screen layer is an adhesive layer in which the light-diffusing fine particles are dispersed in an adhesive.

4. The mirror-type projection screen according to any one of claims 1 to 3, characterized in that the transparent screen layer is a hard coat layer formed from a hard coat layer composition containing the light-diffusing fine particles.

5. The mirror-type projection screen according to any one of claims 1 to 4, characterized in that the haze value of the mirror-type projection screen is 1% or more and 60% or less.

6. The mirror-type projection screen according to any one of claims 1 to 5, characterized in that it comprises a light-transmitting member laminated on at least one of the surfaces of the half-mirror film and the transparent screen layer.

7. The mirror-type projection screen according to claims 1 to 6, characterized in that it is for forming an in-vehicle mirror that is mounted on the exterior of a vehicle.

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