JPWO2021131393A5 - - Google Patents

Description

TECHNICAL FIELD The present application relates to a screen film having excellent optical properties, projection properties and scratch resistance, and a projection system having the same.

In recent years, in commercial facilities with full glass walls, convenience stores, department stores, clothing stores, show windows of stores such as automobiles, etc., windows and windows have been replaced by conventional signboards, posters, and large-screen displays as advertisements, guidance, and information media. By attaching a transparent screen to the show window, the window itself can be made into a large screen, and advertisements and product information can be displayed from the indoor side using a projector while maintaining transparency visibility at a level where the indoor conditions and products can be seen from the outdoor side. So-called digital signage, which projects and displays various other content images, has a very high eye-catching effect for people on the outdoor side, is easy to respond to changes in content, and is simple. (For example, Patent Documents 1 to 4).

Patent Document 1 discloses a transmissive screen having a light diffusion layer containing a light diffusion element in a transparent binder, wherein the light diffusion element has a relative refractive index n with respect to the refractive index of the transparent binder. Transmission screens with an overall haze of 10-85% using hollow beads of 0.75 or less have been proposed. In the transmissive screen of Patent Document 1, hollow beads, which are spherical fine particles, are used to lower the refractive index of the light diffusion layer. It is considered that sufficient projection properties cannot be obtained simply by using fine particles with an insufficient refractive index difference and a low refractive index.

In Patent Document 2, a resin layer and inorganic particles contained in the resin layer are included, and the primary particles of the inorganic particles have a median diameter of 0.1 to 50 nm and a diameter of 10 to 500 nm. A transparent screen film has been proposed, which has a maximum particle size, the content of the inorganic particles is 0.015 to 1.2% by mass with respect to the resin, and the inorganic particles are metallic particles. there is In the transparent screen film of Patent Document 2, a film having a resin layer containing inorganic particles is used. In addition, since the particles having the above median diameter and maximum particle diameter have a particle size distribution in the coating film smaller than that in the visible light range, it is considered that a sufficient light scattering effect is not obtained and projection properties are difficult to obtain.

Patent Document 3 discloses a resin medium, first particles dispersed in the resin medium having a median diameter of 50 nm or more and 360 nm or less, and particles dispersed in the resin medium having a median diameter of 500 nm or more. 5 μm or less and second particles having a diamond structure, wherein the total content of the first particles and the second particles is equal to or less than 100 parts by mass of the resin medium 0.01 parts by mass or more and 20.0 parts by mass or less, and the particle number ratio M ₁ /M ₂ between the number M ₁ of the first particles and the number M ₂ of the second particles is 100 or more and 5000 or less A projection screen with a light scatterer having a total light transmittance of 80% or more has been proposed. The projection screen of Patent Document 3 uses a light scatterer containing particles having a diamond structure, but it is considered that it is difficult to obtain sufficient projection performance using only the light scatterer.

Patent Literature 4 proposes a transparent heat-shielding member having a transparent screen function, which includes a light-diffusing adhesive layer using an adhesive in a transparent resin in which light-diffusing particles are dispersed. In the transparent heat-shielding member having a transparent screen function of Patent Document 4, the light diffusing filler is dispersed only in the light diffusing adhesive layer, and the refractive index difference between the light diffusing filler and the adhesive is small. It is thought that it is difficult to obtain such a projective property.

Japanese Patent No. 4847329 Japanese Patent No. 5752834 JP 2019-113657 A JP 2016-186627 A

The present application solves the above-mentioned problems of the conventional screen film, and provides a screen film excellent in optical properties, projection properties and scratch resistance, and a projection system having the same.

The screen film disclosed in the present application is a screen film including a transparent substrate, a protective layer, a light diffusion layer, and a light diffusion adhesive layer, wherein the protective layer is located on one main surface side of the transparent substrate. The light diffusion layer and the light diffusion adhesive layer are arranged in this order from the other main surface side of the transparent base material, and the light diffusion layer comprises a first light diffusion filler, a resin, and and the light diffusing adhesive layer includes a second light diffusing filler and an adhesive, and the refractive index of the first light diffusing filler and the refractive index of the second light diffusing filler is 0.50 or more.

A projection system disclosed in the present application is a projection system including the screen film disclosed in the present application and a projector.

INDUSTRIAL APPLICABILITY The present application can provide a screen film having excellent optical properties, projection properties, and scratch resistance, and a projection system having the screen film.

FIG. 1 is a schematic cross-sectional view showing an example of the screen film disclosed in the present application. FIG. 2 is a schematic diagram for explaining the method for evaluating the projection properties of the screen film disclosed in the present application.

(screen film)
An embodiment of the screen film disclosed in the present application will be described. The screen film of this embodiment includes a transparent substrate, a protective layer, a light diffusion layer, and a light diffusion adhesive layer, the protective layer being disposed on one main surface side of the transparent substrate, The light diffusion layer and the light diffusion adhesive layer are arranged in this order from the other main surface side of the transparent base material, and the light diffusion layer contains a first light diffusion filler and a resin, The diffusion adhesive layer contains a second light diffusing filler and an adhesive, and the difference between the refractive index of the first light diffusing filler and the refractive index of the second light diffusing filler is 0. .50 or higher.

In the screen film of this embodiment, the light diffusion layer is arranged between the transparent substrate and the light diffusion adhesive layer, so that the scratch resistance of the screen film can be improved. That is, after application of the screen film, the film surface is easily damaged by contact during cleaning, scratches by fingernails, rain, chemicals such as cleaners, and other external factors. On the other hand, although the protective layer can protect the surface to some extent, the protective layer deteriorates little by little with long-term use. Therefore, if the light diffusion layer is positioned closer to the protective layer than the transparent base material, the light diffusion layer is likely to be damaged due to deterioration of the protective layer due to long-term use. A clear image cannot be projected. On the other hand, by arranging the light diffusion layer between the transparent base material and the light diffusion adhesive layer, the scratch resistance of the screen film can be improved and the projection property can be maintained.

In addition, by including the light diffusing filler in both the light diffusing layer and the light diffusing adhesive layer, sufficient brightness of the projected image can be achieved compared to the case where only the light diffusing layer contains the light diffusing filler. Obtainable. That is, by including a light diffusing filler in the light diffusion adhesive layer, the thickness of the light diffusion adhesive layer can be used to efficiently diffuse the light diffused by the light diffusion layer and further by the light diffusion adhesive layer. The light that passes through the diffusion layer without diffusing can also be diffused by the light diffusion adhesive layer, and the brightness of the image can be improved.

Furthermore, by setting the difference between the refractive index of the first light diffusing filler and the refractive index of the second light diffusing filler to 0.50 or more, a clearer image can be provided. That is, when the screen film of this embodiment is used as a transmissive screen film, the light incident from the projector is transmitted through the protective layer, the transparent base material, the light diffusion layer, and the light diffusion adhesive layer in this order, and an image is seen by the human eye. recognized as Here, since the refractive index of the light diffusion layer is high, the light entering from the projector can be efficiently diffused by the filler in the light diffusion layer to provide a high-brightness image. is further diffused by At this time, the larger the refractive index difference between the filler in the light diffusion layer and the filler in the light diffusion adhesive layer, the clearer the image can be provided.

The screen film of this embodiment preferably has a total light transmittance of 60 to 90% and a haze value of 5.0 to 30.0%. The JIS standard for films for architectural windows (JIS K5759) defines a transparent film as having a total light transmittance of 60% or more. That is, if the total light transmittance is 60% or more, it can be said that the film is transparent so that information can be recognized through the film even when the film is not projected by a projector. Regarding the haze value, the lower the haze value, the less fogging, the easier it is to obtain information through the film when not projecting, and the higher the transparency. diffusion is not obtained, and the projection property may be insufficient. On the other hand, when the haze value is 30% or more, the projection property is likely to be obtained, but the transparency may be insufficient in the non-projection state, resulting in lack of transparency.

The protective layer preferably contains an ionizing radiation-curable resin or a thermosetting resin. This is because these resins have high hardness and excellent scratch resistance.

The refractive index of the first light diffusing filler is preferably 1.85 or more and less than 2.75. The higher the refractive index of the filler used in the light diffusion layer, the more efficiently the filler reflects the incident light during projection by the projector, making it possible to recognize a clear image with a wide viewing angle.

The average particle size of the first light diffusing filler is preferably 0.05 to 1.5 μm. In order to efficiently scatter the light forward by the light diffusion layer against the light projected by the projector, it is good to apply a phenomenon called "Mie scattering". Light can be most efficiently scattered forward by being present in a region of about 0.3 to 1.2 μm. Therefore, when the average particle diameter of the filler is less than 0.05 μm, the filler is too fine, and light in the visible light region passes through the light diffusion layer, and the light cannot be diffused efficiently, resulting in insufficient projection properties. Become. On the other hand, when the average particle size of the filler exceeds 1.5 μm, geometric scattering and absorption of light by the particles occur, and light scattering in the forward direction becomes weak. sexuality declines.

Here, the average particle size means an average primary particle size or an average dispersed particle size. This is because when the filler particles are minute, the primary particles may aggregate and exist as aggregated particles. Generally, when the same particles are compared, the average dispersed particle size is larger than the average primary particle size.

The first light diffusing filler is preferably at least one selected from the group consisting of diamond, titanium oxide and zirconium oxide. These materials have a high refractive index, can diffuse light efficiently, and can provide an image with high brightness and a wide viewing angle when projected.

The content of the first light diffusing filler is preferably 0.5 to 5.0% by mass with respect to the total solid content of the light diffusing layer. If the content is less than 0.5% by mass, the transmitted light cannot be diffused sufficiently, making it difficult to obtain clear images.

The film thickness of the light diffusion layer is preferably 0.5 to 10.0 μm. If the film thickness is less than 0.5 μm, the light cannot be diffused sufficiently, and if it exceeds 10 μm, the total light transmittance of the film tends to decrease, the haze value tends to increase, and the transparency during non-projection decreases.

The refractive index of the second light diffusing filler is preferably 1.20 or more and less than 1.50. The larger the difference between the refractive index of the second light diffusing filler contained in the light diffusing adhesive layer and the refractive index of the first light diffusing filler contained in the light diffusing layer, the clearer the image can be recognized. Therefore, the refractive index of the second light diffusing filler is set lower than the refractive index of the first light diffusing filler. In addition, as a result, the difference between the refractive index of the adhesive contained in the light diffusion adhesive layer and the refractive index of the second light diffusing filler increases, so that light can be efficiently diffused and the light diffusion layer The diffused visible light can be made clearer, and the light that has passed through the light diffusion layer without being diffused can be diffused by the light diffusion adhesive layer.

The second light diffusing filler is spherical and preferably has an average particle size of 0.1 to 1.5 μm. Also in this case, it is preferable to apply a phenomenon called "Mie scattering" as in the case of the first light diffusing filler. When the light diffusing filler has a spherical shape, the light from the projector that is incident straight ahead is more efficiently scattered forward, and the visibility of the image from the front of the screen is improved. On the other hand, if the average particle size is less than 0.1 μm, the particle size is smaller than that in the visible light range, so that visible light is transmitted, and the light cannot be diffused efficiently, resulting in insufficient projection properties. Furthermore, when the average particle size exceeds 1.5 μm, geometric scattering and absorption of light by particles occur in the same manner as in the light diffusing layer, light scattering in the forward direction becomes weak, and since the particles are large, the internal haze increases. and the film becomes less transparent. As described above, the average particle size means the average primary particle size or the average dispersed particle size.

The content of the second light diffusing filler is preferably 0.2 to 5.0% by mass with respect to the total solid content of the light diffusing adhesive layer. If the content is less than 0.2% by mass, the transmitted light cannot be diffused sufficiently, making it difficult to obtain clear images. There is a concern that it will cause it to peel off easily after it is applied to the window.

The light diffusion adhesive layer preferably contains an acrylic adhesive. When the screen film of this embodiment is applied to a window glass, it is generally applied by a method called "water application". This is done by sufficiently wetting the windowpane with water containing a surfactant and pasting the film on the windowpane. It is a method of extracting and fixing together. It is easy to control the functional groups of acrylic pressure-sensitive adhesives, and it is easy to form an adhesive layer with excellent water drainage properties when applying water and adhesion to glass after application. By dispersing the light diffusing filler in this acrylic adhesive, in addition to the light diffusibility of the light diffusion layer single film, the thickness of the light diffusion adhesive layer is used to efficiently diffuse light and improve brightness. A high projection image can be provided.

The film thickness of the light diffusion adhesive layer is preferably 10 to 50 μm. If the film thickness is less than 10 μm, the adhesive strength is not sufficient, and there is a concern that the adhesive layer may be peeled off after application. When the film thickness exceeds 50 μm, the adhesive strength is saturated, and the thickness of the light diffusion adhesive layer reduces the transmittance, thereby impairing the transparency during non-projection.

The screen film of this embodiment not only has a transmission screen function that allows the image projected from the projector to be viewed as a transmission image from the opposite side of the projector, but also has a transmission screen function that allows the projected image to be viewed as a reflection image from the projector side. It also has a reflective screen function that can be visually recognized as

Each constituent member of the screen film of this embodiment will be described below.

<Transparent substrate>
The transparent substrate is not particularly limited as long as it is made of a material having translucency. Examples of the transparent substrate include polyester-based resins (e.g., polyethylene terephthalate, polyethylene naphthalate, etc.), polycarbonate-based resins, polyacrylic acid ester-based resins (e.g., polymethyl methacrylate, etc.), alicyclic polyolefin-based resins, polystyrene-based resins (e.g., polystyrene, acrylonitrile-styrene copolymer, etc.), polyvinyl chloride-based resins, polyvinyl acetate-based resins, polyethersulfone-based resins, cellulose-based resins (e.g., diacetylcellulose, triacetylcellulose, etc.), A resin such as a norbornene-based resin processed into a film or sheet can be used. Examples of the method for processing the resin into a film or sheet include extrusion molding, calendar molding, compression molding, injection molding, and a method of dissolving the resin in a solvent and casting it. Additives such as antioxidants, flame retardants, heat stabilizers, ultraviolet absorbers, lubricants, and antistatic agents may be added to the resin. The thickness of the transparent substrate is, for example, 10 μm or more and 500 μm or less, and preferably 25 μm or more and 125 μm or less in consideration of workability and cost.

<Protective layer>
The protective layer is arranged on one main surface side of the transparent base material, and is usually formed directly on the main surface of the transparent base material. The protective layer can be composed of an ionizing radiation-curable resin or a thermosetting resin. This can improve the scratch resistance of the protective layer.

The thickness of the protective layer is preferably 2 μm to 5 μm, more preferably 3 μm to 4 μm. If the thickness of the protective layer is within this range, sufficient scratch resistance can be obtained.

[Ionizing radiation curable resin]
The protective layer made of the ionizing radiation-curable resin is formed by irradiating an ionizing radiation-curable resin oligomer or an ionizing radiation-curable resin monomer with ionizing radiation to cure it.

The weight average molecular weight of the ionizing radiation-curable resin oligomer is preferably 10,000 to 100,000. When the weight-average molecular weight is within the above range, the coatability of the protective layer-forming coating solution used for forming the protective layer can be improved, and the scratch resistance of the formed protective layer can be improved. In the present application, the weight average molecular weight of the oligomer is measured by GPC (gel permeation chromatography) method.

That is, if the weight-average molecular weight is less than 10,000, repelling may occur when the protective layer-forming coating liquid is applied to a transparent substrate. In addition, when the weight average molecular weight is more than 100,000, the number of unsaturated bond groups that act as reaction points per molecular weight generally decreases when curing with ionizing radiation. There is a tendency that the abrasion resistance as a layer cannot be exhibited sufficiently.

As the ionizing radiation-curable resin oligomer having a weight average molecular weight of 10,000 to 100,000, for example, polyfunctional acrylate oligomers such as urethane-based, epoxy-based and polyester-based oligomers can be used. Among them, urethane-based polyfunctional acrylate oligomers are preferable because the hardness and flexibility of the protective layer to be formed are easily balanced. The urethane-based polyfunctional acrylate oligomer can be obtained, for example, by reacting a urethane acrylate having an acrylate polymer in its main chain skeleton and having a reactive acryloyl group at its end.

A commercially available product can also be used for the polyfunctional acrylate oligomer. For example, "BPZA-66" and "BPZA-100" (trade name) manufactured by Kyoeisha Chemical Co., Ltd., "Acryt 8KX-012C" and "8KX-077" (trade name) manufactured by Taisei Fine Chemical Co., Ltd., manufactured by Hitachi Chemical Co., Ltd. "Hitaroid 7975", "Hitaroid 7975D", "Hitaroid 7988" (trade name), "ACA-200M", "ACA-230AA", "ACA-Z250", "ACA-Z251" manufactured by Daicel Allnex, "ACA-Z300", "ACA-Z320" (trade name), etc. can be used.

An ionizing radiation-curable resin monomer can be used in place of the ionizing radiation-curable resin oligomer as long as the film-forming properties of the protective layer-forming coating liquid on the transparent substrate are not deteriorated. A polyfunctional acrylate monomer having two or more saturated groups can be used. Specifically, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) ) acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1, Acrylates such as 2,3-cyclohexane trimethacrylate; Polyurethane polyacrylates such as pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer; Esters produced from polyhydric alcohols such as polyester polyacrylate and (meth)acrylic acid; ,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone and other vinylbenzenes and derivatives thereof.

The ionizing radiation-curable resin monomer can also be used by mixing with the ionizing radiation-curable resin oligomer.

[Thermosetting resin]
Examples of thermosetting resins that can be used include silicone resins, phenol resins, urea resins, diallyl phthalate resins, melamine resins, unsaturated polyester resins, polyurethane resins, and epoxy resins. The protective layer made of the thermosetting resin is formed by heating and curing a thermosetting resin precursor.

In order to improve the hardness of the formed protective layer, the thermosetting resin precursor is preferably a silicone resin precursor, and among the silicone resin precursors, a thermosetting resin precursor comprising an alkoxysilane compound is the most preferred. preferable.

Examples of the thermosetting resin precursor made of the alkoxysilane compound include "KP-86" (trade name) manufactured by Shin-Etsu Silicone Co., Ltd., "SHC-900" and "Tosgard 510" manufactured by Momentive Performance Materials Japan. (product name) and the like.

<Light diffusion layer>
The light diffusion layer is arranged on the side opposite to the side on which the protective layer is arranged on the transparent substrate, and is usually arranged directly on the transparent substrate on the side opposite to the side on which the protective layer is arranged. be. The light diffusing layer is composed of a layer in which the first light diffusing filler is dispersed in a transparent resin.

The transparent resin generally has a refractive index different from the refractive index of the first light diffusing filler dispersed in the resin. The refractive index of the transparent resin is preferably selected within the range of 1.45 to 1.60. In addition, the greater the absolute value of the difference in refractive index between the transparent resin and the first light diffusing filler, the greater the light diffusion effect.

The transparent resin used in the light diffusing layer is not particularly limited as long as it has optical transparency. (Meth)acrylate resin, epoxy (meth)acrylate resin, polyurethane resin, epoxy resin, polycarbonate resin, cellulose resin, acetal resin, vinyl resin, polyethylene resin, polystyrene resin, polypropylene resin , ethylene/vinyl acetate resins, polyamide resins, polyimide resins, melamine resins, phenol resins, silicone resins, fluorine resins and other thermoplastic resins, thermosetting resins, ionizing radiation curable resins, and natural Known resins such as rubber-based resins, recycled rubber-based resins, chloroprene rubber-based resins, nitrile rubber-based resins, and styrene/butadiene rubber-based resins can be suitably used. In addition, one or more of various additives such as cross-linking agents, ultraviolet absorbers, antioxidants, antistatic agents, flame retardants, plasticizers, and colorants are added to the transparent resin according to the purpose. can be anything.

As the first light diffusing filler used in the light diffusion layer, if the difference in refractive index from the second light diffusing filler used in the light diffusion adhesive layer can be 0.50 or more, inorganic fine particles and organic fine particles Either can be used.

Examples of the inorganic fine particles include silica (refractive index: 1.46), alumina (refractive index: 1.77), rutile titanium dioxide (refractive index: 2.72), anatase titanium dioxide (refractive index: 2.52 ), zinc oxide (refractive index: 2.00), zinc sulfide, white lead (refractive index: 1.99), antimony oxides, zinc antimonate, lead titanate, potassium titanate, barium titanate (refractive index: 2.41), zirconium oxide (refractive index: 2.21), cerium oxide, hafnium oxide (refractive index: 1.91), tantalum pentoxide, niobium pentoxide (refractive index: 2.32), yttrium oxide, oxide Chromium, tin oxide (refractive index: 2.38), molybdenum oxide, indium tin oxide (refractive index: 1.86), antimony-doped tin oxide, calcium carbonate, talc, silicate glass, phosphate glass, boron Conventionally known materials such as oxide glass such as acid glass, diamond (refractive index: 2.42), aluminum nitride (refractive index: 2.17), silicon nitride (refractive index: 2.02) can be used as appropriate. be.

Among the above inorganic fine particles, diamond, titanium oxide and zirconium oxide are preferred. This is because these inorganic fine particles have a refractive index in the range of 1.85 or more and less than 2.75. In particular, diamond with a higher refractive index is preferred. Among diamonds, polycrystalline diamond is particularly preferable in terms of dispersibility and cost. When polycrystalline diamond is used as the first light-diffusing filler, the transparent resin is preferably a resin having a hydroxyl group, such as a polyester-based resin. This is because polycrystalline diamond has high hydrophilicity, so that dispersibility in a resin having a hydroxyl group is improved.

Examples of the organic fine particles include acrylic polymers, acrylonitrile polymers, styrene-acrylic copolymers, vinyl acetate-acrylic copolymers, vinyl acetate polymers, ethylene-vinyl acetate copolymers, chlorinated polyolefin polymers, Multicomponent copolymers such as ethylene-vinyl acetate-acrylic, SBR, NBR, MBR, carboxylated SBR, carboxylated NBR, carboxylated MBR, polyvinyl chloride resin, polyvinylidene chloride resin, polyester resin, polyolefin resin , polyurethane resins, polymethacrylate resins, polytetrafluoroethylene resins, polymethyl methacrylate resins, polycarbonate resins, polyvinyl acetal resins, rosin ester resins, episulfide resins, epoxy resins, silicone resins, Conventionally known resins such as silicone-acrylic resins and melamine resins can be used as appropriate.

The shape of the first light diffusing filler may be any shape such as spherical, flat, irregular, star-shaped, and confetti. Hollow particles and core-shell particles may also be used. The light diffusing particles may be used alone or in combination of two or more.

As described above, the refractive index of the first light diffusing filler is preferably 1.85 or more and less than 2.75, and the average particle size of the first light diffusing filler is, as described above, 0.05. It is preferably ˜1.5 μm. Moreover, as described above, the content of the first light diffusing filler in the light diffusion layer is preferably 0.5 to 5.0% by mass with respect to the total solid content of the light diffusion layer. Furthermore, the film thickness of the light diffusion layer is preferably 0.5 to 10.0 μm as described above.

The light diffusion layer may be formed on the transparent substrate via an easy-adhesion layer, an adhesion layer, or the like.

The method for forming the light diffusion layer is not particularly limited, but the transparent resin may be mixed with an organic solvent such as ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, or methanol. , alcohol such as ethanol, or a solution in which the first light diffusing filler is dispersed in a solution dissolved in water is preferably applied to the transparent base material and dried.

Dispersion of the first light-diffusing filler in the transparent resin can be carried out using various mixing/stirring devices and dispersing devices such as a disper, an agitator, a ball mill, an attritor, and a sand mill. Further, if necessary, a dispersing agent for the light diffusing filler may be added for dispersion. It is preferable to defoam the paint in which the light diffusing filler is dispersed before coating in order to prevent air bubbles from remaining in the light diffusing layer after coating and drying.

Coating of the paint in which the first light diffusing filler is dispersed can be performed using a coater such as a die coater, a comma coater, a reverse coater, a dam coater, a doctor bar coater, a gravure coater, a micro gravure coater, and a roll coater. can.

<Light diffusion adhesive layer>
The light-diffusing pressure-sensitive adhesive layer is arranged outside the light-diffusing layer, but is usually directly formed on the light-diffusing layer. The light diffusion adhesive layer consists of a layer in which the second light diffusion filler is dispersed in the adhesive.

As a material for the adhesive, a material having a high visible light transmittance and a small difference in refractive index from the transparent substrate is preferably used. Examples include resins such as acrylic resins, silicone resins, polyester resins, epoxy resins, and polyurethane resins. In particular, acrylic resins have high optical transparency, wettability and adhesion. It is more suitable for use because it has a good balance of forces, is highly reliable and has many achievements, and is relatively inexpensive.

Examples of the acrylic pressure-sensitive adhesive include homopolymers or copolymers of acrylic monomers such as acrylic acid and its esters, methacrylic acid and its esters, acrylamide and acrylonitrile, and at least one of the above acrylic monomers and acetic acid. Examples include copolymers with vinyl monomers such as vinyl, maleic anhydride, and styrene. Tg (glass transition temperature) of the acrylic pressure-sensitive adhesive is in the range of -60 ° C. to -10 ° C., and the weight average molecular weight is preferably in the range of 100,000 to 2,000,000, particularly 500,000 Those in the range of ~1,000,000 are more preferred. For the acrylic pressure-sensitive adhesive, one or a mixture of two or more cross-linking agents such as isocyanate-based, epoxy-based, and metal chelate-based cross-linking agents can be used as necessary.

As the second light diffusing filler used in the light diffusion adhesive layer, if the difference in refractive index from the first light diffusing filler used in the light diffusion layer can be 0.50 or more, the above-mentioned first light Both inorganic fine particles and organic fine particles that can be used in diffusible fillers can be used.

As described above, the refractive index of the second light diffusing filler is preferably 1.20 or more and less than 1.50. The second light diffusing filler is spherical and has an average particle diameter of , it is preferably 0.1 to 1.5 μm. Further, the content of the second light diffusing filler in the light diffusing adhesive layer is, as described above, preferably 0.2 to 5.0% by mass with respect to the total solid content of the light diffusing adhesive layer. . Furthermore, the film thickness of the light diffusion adhesive layer is preferably 10 to 50 μm as described above.

The method for forming the light diffusing adhesive layer is not particularly limited, but a paint is prepared by adding and dispersing a light diffusing filler to a solution in which the above adhesive is dissolved in an organic solvent. Using a coater such as a die coater, a comma coater, a reverse coater, a dam coater, a doctor bar coater, a gravure coater, a micro gravure coater, or a roll coater, the paint is first applied on the release film, dried, and then light diffusion adhesive It is preferable to form the exposed surface of the layer by a method of adhering it to the surface of the light diffusion layer.

Next, an example of the screen film of this embodiment will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of the screen film of this embodiment. In FIG. 1, the screen film 10 includes a transparent substrate 11, a protective layer 12, a light diffusion layer 13, and a light diffusion adhesive layer . The light diffusing layer 13 contains a first light diffusing filler and a resin, the light diffusing adhesive layer 14 contains a second light diffusing filler and an adhesive, and the refractive index of the first light diffusing filler is and the refractive index of the second light diffusing filler is set to 0.50 or more.

In the screen film 10, the light diffusion layer 13 is arranged between the transparent substrate 11 and the light diffusion adhesive layer 14, and the protective layer 12 is formed on the surface of the transparent substrate 11 on which the light diffusion layer 13 is formed. , the scratch resistance of the screen film 10 can be improved. Further, since the difference between the refractive index of the first light diffusing filler and the refractive index of the second light diffusing filler is set to 0.50 or more, the optical properties and projection properties of the screen film 10 are improved. can.

Although not shown in FIG. 1, by disposing a release layer made of a release film on the outer surface of the light diffusion adhesive layer 14, the handleability of the screen film 10 before being attached to a glass substrate or the like is improved. can be done.

(projection system)
Next, embodiments of the projection system disclosed in the present application will be described. The projection system of this embodiment includes the screen film disclosed in the above embodiment and a projector that projects an image onto the screen film. Since the projection system of this embodiment includes the screen film disclosed in the above embodiment, it is excellent in projectability and angle dependency as shown in the examples described later.

The projection system can additionally include, for example, a transmission device that transmits video data to the projector, a control device that controls the projector, and the like.

The screen film disclosed in the present application will be described below based on examples. However, the screen film disclosed in the present application is not limited to the following examples.

(Example 1)
<Formation of protective layer>
First, as a transparent substrate, a polyethylene terephthalate (PET) film "A4300" (trade name, thickness: 50 µm) manufactured by Toyobo Co., Ltd., both surfaces of which were treated for easy adhesion, was prepared. Next, on one side of the PET film, using a micro gravure coater (manufactured by Kadoiseiki Co., Ltd.), a hard coat paint "LCH2500" (trade name) manufactured by Toyochem Co., Ltd. is applied to a thickness of 3 μm after drying. After drying, the film was cured by irradiating it with UV rays of 300 mJ/cm ² from a high-pressure mercury lamp to form PET film A with a protective layer having a thickness of 3 µm.

<Formation of Light Diffusion Layer>
98.5 parts of pure water is added to 1.5 parts of polycrystalline diamond particles "DPC-0-2" (trade name, refractive index: 2.41) manufactured by Vision Development Co., Ltd., and an ultrasonic dispersion machine "UH-600 (trade name, manufactured by SMT Co., Ltd.) at a liquid temperature of 30° C. and a pulse rate of 70% for 1 hour to prepare a diamond dispersion.

Next, to 16 parts of this diamond dispersion, 39 parts of a polyester resin solution "Pluscoat RZ-105" (trade name, refractive index: 1.52, solid content concentration: 25% by mass) manufactured by Goo Chemical Co., Ltd. After adding 40 parts of water and 5 parts of methanol and mixing and blending with a disper, the mixture was passed through a filter with a diameter of 5 μm to prepare a coating liquid for forming a light diffusion layer. When the average particle size of the polycrystalline diamond in this coating liquid was measured with a laser diffraction/scattering particle size distribution meter "LA-960V2" manufactured by HORIBA, the average dispersed particle size was 0.8 μm. The coating liquid had a solid concentration of 10.0% by mass and a filler content of 2.4% by mass relative to the total solid content.

The coating liquid for forming a light diffusion layer is applied to the opposite side of the surface on which the protective layer of the protective layer-attached PET film A is formed using a gravure coater so that the thickness after drying is 3 μm, and dried. By doing so, the light diffusion layer A was formed.

<Formation of light diffusion adhesive layer>
First, a PET film “J0-L” (trade name, thickness: 38 μm) manufactured by Nippa and having one side treated with silicone was prepared as a release film. In addition, for 100 parts of Soken Chemical's acrylic adhesive solution "SK Dyne 2094" (trade name, solid content concentration: 25% by mass, refractive index: 1.49), Momentive Performance Materials Japan 0.50 parts of spherical silicone resin fine particles "XC99-A8808" (trade name, average particle diameter: 0.7 μm, refractive index: 1.42) [3.5 parts per 100 parts of adhesive resin], Add 1.25 parts of an ultraviolet absorber (benzophenone type) manufactured by Wako Pure Chemical Industries, Ltd. and 0.27 parts of a cross-linking agent “E-AX” manufactured by Soken Chemical Co., Ltd. (trade name, solid content concentration: 5% by mass), After dispersing and blending with a disper, defoaming was performed to prepare a coating liquid for forming a light-diffusing pressure-sensitive adhesive layer. The coating liquid had a solid content concentration of 26.2% by mass and a filler content of 1.9% by mass based on the total solid content.

Next, using a die coater, the coating liquid for forming the light diffusion adhesive layer is applied onto the silicone-treated side of the release PET film so that the thickness after drying becomes 28 μm, and dried. By doing so, the light diffusion adhesive layer A was formed. Furthermore, the previously prepared light diffusion layer A is attached to the exposed surface of the light diffusion adhesive layer A, and the light diffusion adhesive layer A and the light diffusion layer A are provided on one side of the PET film, and the protective layer is provided on the other side of the PET film. The formed transparent screen film of Example 1 was produced.

(Example 2)
The dispersion time of the polycrystalline diamond "DPC-0-2" during the formation of the light diffusion layer A was changed to 2.0 hours. A diamond dispersion was prepared in the same manner as in Example 1, except that centrifugation was performed at 8000 rpm for 5 minutes at 25° C. using an LN rotor. The solid content concentration after centrifugation was 1.0% by mass.

A coating solution for forming a light diffusion layer was prepared in the same manner as in Example 1, except that 16 parts of the dispersion was used. This coating liquid had an average dispersed particle size of diamond of 0.3 μm, a solid content concentration of 10.0% by mass, and a filler content of 2.4% by mass based on the total solid content, which were measured in the same manner as in Example 1. rice field. A light diffusion layer B was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was attached to the light diffusion layer B in the same manner as in Example 1 to prepare a transparent screen film of Example 2.

(Example 3)
A coating solution for forming a light diffusion layer was prepared in the same manner as in Example 1, except that the dispersion time of the polycrystalline diamond "DPC-0-2" during the formation of the light diffusion layer A was changed to 0.5 hours. This coating liquid had an average dispersed particle diameter of 1.2 μm, a solid content concentration of 10.0% by mass, and a filler content of 2.4% by mass based on the total solid content, as measured in the same manner as in Example 1. rice field. A light diffusion layer C was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was attached to the light diffusion layer C in the same manner as in Example 1 to prepare a transparent screen film of Example 3.

(Example 4)
A light diffusion layer D was formed in the same manner as in Example 1, except that the film thickness of the light diffusion layer A was changed to 1 μm. The light diffusion adhesive layer A was attached to the light diffusion layer D in the same manner as in Example 1 to prepare a transparent screen film of Example 4.

(Example 5)
A light diffusion layer E was formed in the same manner as in Example 1, except that the film thickness of the light diffusion layer A was changed to 8 μm. The light diffusion adhesive layer A was attached to the light diffusion layer E in the same manner as in Example 1 to prepare a transparent screen film of Example 5.

(Example 6)
Instead of the spherical silicone resin particles "XC99-8808" in the coating liquid for forming the light diffusion adhesive layer, a spherical silicone resin dispersion "SCK-010MW" manufactured by Chugoku Kako Co., Ltd. (trade name, primary particle diameter: 0.1 μm, A light diffusion adhesive layer B was formed in the same manner as in Example 1, except that the refractive index: 1.42) was replaced with the same amount of the solid content of the silicone resin. The light diffusion layer A was attached to the light diffusion adhesive layer B in the same manner as in Example 1 to prepare a transparent screen film of Example 6.

(Example 7)
Instead of the spherical silicone resin particles "XC99-8808" in the coating liquid for forming the light diffusion adhesive layer, a spherical silicone resin dispersion "SCK-100MW" manufactured by Chugoku Kako Co., Ltd. (trade name, primary particle diameter: 1.1 μm, A light diffusion adhesive layer C was formed in the same manner as in Example 1, except that the refractive index: 1.42) was replaced with the same amount of the solid content of the silicone resin. The light diffusion layer A was attached to the light diffusion adhesive layer C in the same manner as in Example 1 to prepare a transparent screen film of Example 7.

(Example 8)
4.7 parts of the diamond dispersion obtained in Example 1, 39.7 parts of the polyester resin solution "Plascoat RZ-105", 50.6 parts of pure water, and 5 parts of methanol were used. A coating solution for forming a light diffusion layer was prepared in the same manner as in Example 1. This coating liquid had an average dispersed particle diameter of 0.8 μm, a solid content concentration of 10.0% by mass, and a filler content of 0.7% by mass based on the total solid content, which were measured in the same manner as in Example 1. rice field. A light diffusion layer F was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was attached to the light diffusion layer F in the same manner as in Example 1 to prepare a transparent screen film of Example 8.

(Example 9)
31.3 parts of the diamond dispersion obtained in Example 1, 38.1 parts of the polyester resin solution "Pluscoat RZ-105", 25.6 parts of pure water, and 5 parts of methanol were used. A coating solution for forming a light diffusion layer was prepared in the same manner as in Example 1. This coating liquid had an average dispersed particle diameter of 0.8 μm, a solid content concentration of 10.0% by mass, and a filler content of 4.7% by mass relative to the total solid content, which were measured in the same manner as in Example 1. rice field. A light diffusion layer G was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was adhered to the light diffusion layer G in the same manner as in Example 1 to prepare a transparent screen film of Example 9.

(Example 10)
Instead of polycrystalline diamond "DPC-0-2", titanium oxide "TTO-55" manufactured by Ishihara Sangyo Co., Ltd. (trade name, refractive index: 2.72) 30.0 parts, pure water 68.5 parts As a dispersant, 1.5 parts of a polymer dispersant "Dyspa-BYK180" (trade name) available from BYK Chemie was added. (manufactured by Seiki) for 30 minutes. After dispersion, centrifugation was performed at 25° C. and 8000 rpm for 5 minutes using an LN rotor in a centrifuge “H-9R” to prepare a dispersion. The solid content concentration after centrifugation was 28.0% by mass. To 0.9 part of this dispersion, 39 parts of the polyester resin solution "Plascoat RZ-105", 55.1 parts of pure water, and 5 parts of methanol were added, mixed and blended with a disper, and filtered through a filter with a diameter of 5 μm. A coating liquid for forming a light diffusion layer was prepared by passing through the When the average particle size of titanium oxide in this coating liquid was measured with a laser diffraction/scattering particle size distribution meter "LA-960V2" manufactured by HORIBA, the average dispersed particle size was 1.0 μm. The coating liquid had a solid concentration of 10.0 mass % and a filler content of 2.5 mass % relative to the total solid content. A light diffusion layer H was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was attached to the light diffusion layer H in the same manner as in Example 1 to prepare a transparent screen film of Example 10.

(Example 11)
Instead of polycrystalline diamond “DPC-0-2”, a water dispersion of zirconium oxide “SZR-W” manufactured by Sakai Chemical Co., Ltd. (trade name, refractive index: 2.11, solid content concentration: 30% by mass) 1 38.8 parts of the polyester resin solution "Pluscoat RZ-105", 55.2 parts of pure water, and 5 parts of methanol are added to 0.0 part, mixed and blended with a disper, and then filtered through a filter with a diameter of 5 μm. By passing through, a coating liquid for forming a light diffusion layer was prepared. The average particle size of the zirconium oxide in this coating liquid was measured with a laser diffraction/scattering particle size distribution meter “LA-960V2” manufactured by HORIBA, and the average dispersed particle size was 0.2 μm. The coating liquid had a solid concentration of 10.0% by mass and a filler content of 3.0% by mass relative to the total solids. A light diffusion layer I was formed in the same manner as in Example 1, except that this coating solution for forming a light diffusion layer was used. The light diffusion adhesive layer A was attached to the light diffusion layer I in the same manner as in Example 1 to prepare a transparent screen film of Example 11.

(Comparative example 1)
An adhesive layer D was formed in the same manner as in Example 1, except that the spherical silicone resin fine particles "XC99-A8808" were removed from the light diffusion adhesive layer A instead of the light diffusion adhesive layer A of Example 1. The light diffusion layer A was attached to this adhesive layer D in the same manner as in Example 1 to prepare a transparent screen film of Comparative Example 1.

(Comparative example 2)
A comparative example in which a light diffusion adhesive layer A prepared in the same manner as in Example 1 is attached to the PET film A with a protective layer prepared in Example 1 instead of the light diffusion layer A, and does not include a light diffusion layer. No. 2 clear screen films were made.

(Comparative Example 3)
The coating solution for forming a light diffusion layer prepared in Example 1 was applied to a PET film "A4300" which is a transparent base material so as to have a thickness of 3 μm in the same manner as in Example 1, followed by drying. A protective layer was formed thereon in the same manner as in Example 1 to form PET film B with a protective layer. Instead of the light diffusion layer A, the light diffusion adhesive layer A prepared in the same manner as in Example 1 is attached to the PET film B with the protective layer, and the light diffusion layer is formed on the opposite side of the light diffusion adhesive layer A. Also, a transparent screen film of Comparative Example 3 was produced.

(Comparative Example 4)
Instead of the spherical silicone resin fine particles "XC99-A8808" used in the light diffusion adhesive layer A of Example 1, zinc oxide manufactured by Sakai Chemical Co., Ltd. (grade: 1 type, primary particle diameter: 0.75 μm, refractive index: 2.00) was used in the same manner as in Example 1 to form a light diffusion adhesive layer E. To this light diffusion adhesive layer E, the light diffusion layer I of the PET film A with the protective layer and light diffusion layer prepared in Example 11 is attached in the same manner as in Example 1, and the light diffusion layer I and the light diffusion adhesive layer A transparent screen film of Comparative Example 4 was prepared in which the difference in refractive index of the light diffusing filler contained in E was less than 5.0.

<Evaluation of transparent screen film>
For Examples 1 to 11 and Comparative Examples 1 to 4, the optical properties, projection properties, angle dependence and scratch resistance were evaluated as follows.

[optical properties]
In order to evaluate optical properties, total light transmittance and haze value were measured as follows. A transparent screen film is attached to a 3 mm float glass, and the glass surface is the incident light side, and the translucency is measured using a haze meter "NDH2000" (trade name) manufactured by Nippon Denshoku Co., Ltd., according to JIS K7136-2000. Then, the total light transmittance and haze value were calculated.

[Projectivity]
In order to evaluate the projectability, the brightness of the image projected onto the transparent screen film by the projector was measured as follows.

As a projector, an ultra-short projection projector "MP-TW4011" using a laser light source manufactured by Maxell was used. The output of the projector is standard mode, the brightness, contrast, and color depth are all default values, the image quality setting is 4, the video mode is "standard", ACCENTUALIZER is "3", HDCR is "3", and dynamic black is "enabled". , respectively, and projected.

The luminance was measured according to the following procedure. First, a transparent screen film was attached to a 5 mm thick transparent polycarbonate plate (model number: PCTA) manufactured by Misumi Co., Ltd. by applying water so as not to cause air bubbles. got

Next, as shown in FIG. 2, the screen film side of the transparent screen plate 30 composed of the transparent screen film 10 and the transparent polycarbonate plate 20 is placed on the projector 40 side, and the horizontal distance from the light source of the projector 40 to the transparent screen plate 30 is is 500 mm, the vertical distance from the light source to the measurement point is 450 mm, projection light 50 is emitted from the projector 40 , and the luminance of the measurement point is measured from the opposite side of the projector 40 by the luminance meter 60 . As the luminance meter 60, a color luminance meter "BM-7" manufactured by TOPCON was used, and the distance from the measurement point to the lens of the luminance meter 60 was set to 300 mm. All the measurements were performed in a dark room, and white and black images were created using Microsoft's "PowerPoint" to project images, and the white and black luminances were measured.

Evaluation of projection property was performed according to the following criteria.

It can be said that a screen that has a higher brightness when projecting white light is brighter and can provide a clearer image. Therefore, those with a brightness of 50 cd/m ² or more during white projection were rated as excellent (◯), those with a brightness of 30 to 50 cd/m ² were rated as good (Δ), and those with a brightness of less than 30 cd/m ² were rated as poor (x). .

If the brightness during black projection is high, the image tends to be whitish during image projection, and it can be said that a screen with low brightness during black projection can provide a high-contrast image. Therefore, when the luminance during black projection is less than 0.13 cd/m ² , it is excellent (○), 0.13 or more and less than 0.16 cd/m ² is good (Δ), and 0.16 cd/m ² or more. was judged to be defective (x).

[Angle dependence]
The angular dependence of the transparent screen film was evaluated by projecting an image onto the transparent screen plate with a projector in the same manner as the evaluation of the projectability, and evaluating the image in the following three stages.
Excellent (○): When the image can be clearly recognized even when observing while changing the viewing angle. (×): When there are places where it is difficult to recognize the image when observing while changing the viewing angle

[Scratch resistance]
A transparent screen film is attached to a 3 mm float glass, and a sliding tester "HEIDON" manufactured by Shinto Kagaku Co., Ltd. is used to fix steel wool (#0000) to the tip of a sliding part with a diameter of 15 mm, and a load of 883 g is applied. After the film surface was slid back and forth 10 times at 4500 mm/min in this state, an image was projected onto a transparent screen plate with a projector in the same manner as in the evaluation of projection properties, and the white luminance before and after sliding was measured. As a result, when the rate of change in brightness was less than 10% compared to the initial stage, it was rated as excellent (o), and when it was 10% or more, it was rated as defective (x).

The above results are shown in Tables 1 to 3. Tables 1 to 3 also show the layer structure of the transparent screen film and the difference in refractive index between the light diffusing filler in the light diffusing layer and the light diffusing filler in the light diffusing adhesive layer.

From the above evaluation results, the layer structure is protective layer / PET film / light diffusion layer / light diffusion adhesive layer, and the difference in refractive index between the light diffusion filler in the light diffusion layer and the light diffusion filler in the light diffusion adhesive layer is 0. It can be seen that in Examples 1 to 11 of 0.50 or higher, substantially satisfactory evaluations were obtained in all of the optical properties, projection properties, angle dependence and scratch resistance.

On the other hand, in Comparative Example 1 in which an adhesive layer was formed instead of the light diffusion adhesive layer, white luminance was inferior, and in Comparative Example 2 in which no light diffusion layer was formed, white luminance and angle dependence were inferior, and the light diffusion layer was not formed. In Comparative Example 3, which was placed between the protective layer and the transparent base material, the scratch resistance was poor, and the difference in refractive index between the light diffusing filler in the light diffusing layer and the light diffusing filler in the light diffusing adhesive layer was less than 0.50. In Comparative Example 4, which was below, the black brightness was inferior.

The present application can be implemented in forms other than those described above without departing from the spirit of the present application. The embodiments disclosed in this application are examples and are not limiting. The scope of the present application shall be interpreted with priority given to the descriptions in the attached claims rather than the descriptions in the above specification, and all changes within the scope of equivalents to the claims shall be included in the scope of the claims. It is something that can be done.

The screen film disclosed in the present application has excellent optical properties, projection properties, and scratch resistance, and has a transmissive screen function and a reflective screen function, and can be applied to various transparent screens.

REFERENCE SIGNS LIST 10 screen film 11 transparent substrate 12 protective layer 13 light diffusion layer 14 light diffusion adhesive layer 20 transparent polycarbonate plate 30 transparent screen plate 40 projector 50 projection light 60 luminance meter

Claims (14)

A screen film comprising a transparent substrate, a protective layer, a light diffusion layer, and a light diffusion adhesive layer,
The protective layer is arranged on one main surface side of the transparent base material,
The light diffusion layer and the light diffusion adhesive layer are arranged in this order from the other main surface side of the transparent base material,
The light diffusion layer includes a first light diffusion filler and a resin,
The light diffusion adhesive layer contains a second light diffusion filler and an adhesive,
The screen film, wherein the difference between the refractive index of the first light diffusing filler and the refractive index of the second light diffusing filler is 0.50 or more. 2. The screen film according to claim 1, which has a total light transmittance of 60 to 90% and a haze value of 5.0 to 30.0%. 3. The screen film according to claim 1, wherein the protective layer contains an ionizing radiation-curable resin or a thermosetting resin. 4. The screen film according to any one of claims 1 to 3, wherein the first light diffusing filler has a refractive index of 1.85 or more and less than 2.75. The screen film according to any one of claims 1 to 4, wherein the average particle size of the first light diffusing filler is 0.05 to 1.5 µm. The screen film according to any one of claims 1 to 5, wherein the first light diffusing filler is at least one selected from the group consisting of diamond, titanium oxide and zirconium oxide. The screen according to any one of claims 1 to 6, wherein the content of the first light diffusing filler is 0.5 to 5.0 mass% with respect to the total solid content of the light diffusing layer. the film. The screen film according to any one of claims 1 to 7, wherein the light diffusion layer has a thickness of 0.5 to 10.0 µm. The screen film according to any one of claims 1 to 8, wherein the second light diffusing filler has a refractive index of 1.20 or more and less than 1.50. The screen film according to any one of claims 1 to 9, wherein the second light diffusing filler is spherical and has an average particle size of 0.1 to 1.5 µm. The content of the second light diffusing filler is 0.2 to 5.0% by mass with respect to the total solid content of the light diffusing adhesive layer, according to any one of claims 1 to 10. screen film. The screen film according to any one of claims 1 to 11, wherein the light diffusion adhesive layer contains an acrylic adhesive. The screen film according to any one of claims 1 to 12, wherein the light diffusion adhesive layer has a thickness of 10 to 50 µm. A projection system comprising the screen film according to any one of claims 1 to 13 and a projector.

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