JP2006259028A - Transmission screen and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a relatively light-weight transmission screen on which a projected image is vivid with less glare when projected from behind by a projector, at a considerably lower cost than the conventional transmission screens. <P>SOLUTION: The transmission screen comprises a colored transparent plastic substrate and a milk-white light diffusion layer which is formed on the rear side of the substrate and has fine convex and concave faces. The light diffusion layer comprises silica powder having an average particle size of 1.0 to 5.0μm, mixed into transparent resin and plastic beads having an average particle size of 0.5 to 5.0μm smaller than the particle size of silica powder, and the addition amount of silica powder is 4 or more times as large as the added amount of plastic beads, and the total amount of silica powder and plastic beads added is 0.4 to 1.5 times as large as the amount of transparent resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmissive screen with less screen glare and a wide viewing angle when projected from the rear by a projector, and produces a transmissive screen with a clear projected image and a relatively light weight at a much lower cost than before. On how to do.

  In recent elementary and junior high schools, audiovisual education has been promoted under the guidance of the Ministry of Education, Culture, Sports, Science and Technology, and AV education using television receivers, video decks, tape recorders, overhead projectors (OHP), projectors, radios, etc. is thriving. Currently, TV receivers used for daily AV education are relatively easy to operate, but the screen is small and the surface is curved to easily reflect outside light. The image is difficult to see, and the occupied area in the classroom is too large. An OHP with a large screen is clearly advantageous in that it displays a clear and large image, and even a child with a seat behind can easily see the image.

  Commercially available OHPs often use not only front projection type images where children receive an image like a phantom lamp, but also rear-type transmission type screens whose images are similar to movies. Can also be used. Transmission type screens are disclosed in JP-A-55-137513, JP-A-63-199338, JP-B-5-16002, JP-A-2000-330210, JP-A-2001-242546, and registered utility model No. 3010871. As shown, a light diffusion layer is formed on one side of a transparent plastic substrate, and the light diffusion layer is generally less than 1 mm in thickness. Silica (silicon oxide), titanium oxide, acrylic resin, polystyrene resin in the transparent resin Integrate by mixing fine particles such as silicon resin. Even if this transparent plastic substrate is colorless and transparent, as shown in JP-A-63-273850, JP-A-2000-330210, JP-A-2003-228305, etc., a pigment or dye such as carbon black is added. And it may be colored and transparent. Further, as in JP-A-6-67308 and JP-A-2000-330210, a polarizing sheet may be bonded to one or both sides of the screen, or a light absorbing layer may be provided with black ink.

As disclosed in JP-A No. 55-137513, page 1, right column, lines 5 to 17, the transmissive screen does not diffuse light when only a light diffusion layer is formed on one side of a transparent substrate. In many cases, the peripheral portion of the screen is darkened even if sufficient brightness is maintained at the central portion near the light source. For this reason, JP-A-55-137513, JP-A-56-24339, and JP-A-63-4208 form a lens surface on the opposite surface of the substrate sheet provided with the light diffusion layer. A lenticular lens or a Fresnel lens having a light diffusing action. Examples of this type of light diffusion sheet include Japanese Patent Publication No. 5-16002, Japanese Patent Application Laid-Open No. 2002-323608, Japanese Patent Application Laid-Open No. 2003-107219, and the like.
JP-A-55-137513 JP 56-24339 A JP 63-199338 A JP-A-63-273850 Japanese Patent Publication No.5-16002 JP-A-6-67308 JP 2000-330210 A JP 2001-242546 A JP 2002-323608 A JP 2003-107219 A JP 2003-228305 A Japanese Utility Model Publication No. 63-4208 Registered Utility Model No. 3010871

  A transmissive screen provided with a lenticular lens or a lens and a Fresnel lens on one or both sides of a base sheet is not only used as a normal CRT, but also when projecting an image from a liquid crystal (LCD) projector. It is necessary to eliminate the moire phenomenon caused by the interference due to the periodic structure and to clearly resolve an image having a high pixel number such as SXGA, SXGA +, UXGA. Even if the moiré phenomenon can be eliminated by optimizing the projection pixel pitch and the periodic structure of the lens, the pixel pitch projected on the screen becomes very small when the number of pixels is high. For this reason, it is necessary to make the pitch of the lenticular lens very fine so as to be less than 0.1 mm, which requires a high cost for manufacturing the lens mold, and the production efficiency is considerably lowered due to accurate transfer of the lens shape. To do.

  In this type of transmissive screen, a fine diffusing particle contained in the light diffusing layer or the lens is likely to interfere with the projection light and cause a glare of the screen (hereinafter referred to as a speckle phenomenon). To eliminate the speckle phenomenon, dividing the light diffusing layer or providing a concentration gradient of diffusing particles in the thickness direction has some effects, but these measures significantly increase the manufacturing cost of the transmission screen. Resulting in. In addition, the speckle phenomenon and image resolution with a high number of pixels often have a trade-off relationship, and the resolution decreases when the speckle phenomenon is reduced, and the speckle phenomenon tends to increase when the resolution is increased.

  The present invention has been proposed in order to improve the above-mentioned problems associated with a conventional transmission screen, and provides a transmission screen having a high contrast of a projected image, a clear image, a simple structure, and a low cost. The purpose is that. Another object of the present invention is to provide a method for manufacturing a transmission screen that does not require precise molding such as lenticular lens processing.

  The transmissive screen according to the present invention includes a colored transparent plastic substrate and a milky white light diffusion layer having fine uneven surfaces formed on the back surface of the substrate. This light diffusion layer is composed of silica powder having an average particle diameter of 1.0 to 5.0 μm mixed in a transparent resin and plastic beads having an average particle diameter of 0.5 to 5.0 μm smaller than the silica particle diameter. To do. At this time, the addition amount of silica powder is 4 times or more of the addition amount of plastic beads, and the total addition amount of silica powder and plastic beads is 0.4 to 1.5 times the amount of transparent resin.

  The transmission type screen of the present invention comprises a colored transparent plastic substrate, an antistatic surface treatment layer coated and cured on at least one surface of the substrate, and the substrate or surface treatment on the back surface of the plastic substrate. You may consist of the milky-white light-diffusion layer which has the fine uneven surface formed on a layer. This light diffusion layer is composed of silica powder having an average particle diameter of 1.0 to 5.0 μm mixed in a transparent resin and plastic beads having an average particle diameter of 0.5 to 5.0 μm smaller than the silica particle diameter. At this time, the total amount of silica powder and plastic beads added is 0.4 to 1.5 times the amount of transparent resin.

  In the transmission screen according to the present invention, the silica powder is preferably a gel type synthetic silica having an average particle diameter of 1.0 to 3.0 μm. The plastic beads are preferably crosslinked polystyrene, acrylic or polyurethane beads having an average particle size of 0.5 to 2.0 μm.

  In the method for producing a transmission screen according to the present invention, a surface treatment layer is thinly formed on the surface of a tinted colored transparent plastic substrate by vapor deposition, coating or transfer, and then cured, and then milky white by screen printing. The light diffusion layer is printed on the surface treatment layer to a thickness of 5 to 50 μm. The composition of the coating solution for the light diffusion layer is 5 to 40% by weight of silica powder and plastic beads, 20 to 40% by weight of a transparent resin, 40 to 60% by weight of a solvent, and 1 to 10% by weight of a predetermined additive. The amount of silica powder added is very large, such as 0.4 to 1.5 times the amount of transparent resin in the light diffusion layer, and a fine irregular surface is formed on the entire surface of the light diffusion layer.

  In the method of the present invention, the plastic substrate is preferably an acrylic resin plate having a thickness of 1 to 5 mm, and the acrylic resin plate is distorted by forming a thin surface treatment layer on both sides of the acrylic resin plate and curing it. Does not occur. Preferably, the surface treatment layer has a thickness of 0.5 to 5 μm and contains ultrafine powdered tin oxide, zinc oxide, and iridium oxide having a particle size of 0.2 μm or less. It has a high light transmittance as well as preventing property and scratch resistance.

  The present invention will be described with reference to the drawings. FIG. 1 illustrates a transmissive screen 1 according to the present invention. In the transmissive screen 1, a thin light diffusion layer 3 is formed on the back surface of a tinted colored transparent plastic substrate 2. In FIG. 1, an antistatic surface treatment layer 5 is provided in advance on both surfaces of the plastic substrate 2 before the light diffusion layer 3 is formed, and in FIG. 3, the surface treatment layer 5 is provided only on the surface of the plastic substrate 2 in advance. In the screen 6 of FIG. 2, the light diffusion layer 3 is directly formed on the back surface of the plastic substrate 2.

  The plastic substrate 2 shown in FIGS. 1 to 3 is relatively thick, such as 1 to 5 mm in thickness, and its material is acrylic resin, polystyrene resin, polycarbonate resin, methyl methacrylate / vinyl monomer copolymer resin. Etc. are used. In particular, a methacrylic resin is preferable because it has a low birefringence and a high impact resistance that lowers the polarization characteristics of the liquid crystal in the projector. As the methacrylic resin, a methyl methacrylate homopolymer, a vinyl copolymerizable with methyl methacrylate is used. A copolymer containing 50% by weight or less of a monomer is preferred. These copolymerizable vinyl monomers include methyl acrylate, acrylic acid esters such as ethyl acrylate and butyl acrylate, ethyl methacrylate, methacrylic acid esters such as butyl methacrylate and cyclohexyl methacrylate, acrylic acid and methacrylic acid. Examples include acid, styrene, acrylonitrile and the like.

  The plastic substrate 2 is colored and transparent by a tinting process in which a dye or pigment is added to a thermoplastic resin, and this dye or pigment is a light absorber having a maximum absorption wavelength range of 460 to 540 nm. In this light absorber, fine powder carbon black or neodymium compound as a pigment, Plast Blue 8516 (manufactured by Arimoto Chemical), Diaresin Red Z (manufactured by Mitsubishi Chemical), Sumiplast Red 3B (manufactured by Sumitomo Chemical), Sumiplast Examples thereof include Yellow HLR (manufactured by Sumitomo Chemical Co., Ltd.), Cromoft Brown 5R (manufactured by Ciba Geigy) and the like.

  In FIG. 1 or FIG. 3, the surface treatment layer 5 is provided in a thin layer form on both sides or the surface of the plastic substrate 2 in order to impart antistatic properties, and then the light diffusion layer 3 is formed on the back surface of the plastic substrate. is doing. The surface treatment layer 5 contains ultrafine powdered tin oxide, zinc oxide, iridium oxide or the like having a particle size of 0.2 μm or less, and is provided and cured by vapor deposition, coating, transfer, dipping, or the like.

  As the surface treatment layer 5, a dilute coating solution in which a conductive filler such as tin oxide, zinc oxide, iridium oxide or the like of ultra fine powder is added to a polyfunctional acrylate such as urethane acrylate, epoxy acrylate, or polyester acrylate is used. You may make it harden | cure by ultraviolet irradiation after making it adhere to the surface. The preferred surface treatment layer 5 has a high surface resistivity and excellent antistatic properties, and maintains antistatic properties for a long time even when immersed in warm water. The surface treatment layer 5 is an ultrafine powder of added tin oxide, zinc oxide, and iridium oxide, and has a small transparency than the wavelength of light, so that it has good transparency and can substantially maintain the high light transmittance of the plastic substrate 2.

  The surface treatment layer 5 preferably has a thickness of 0.5 to 5 μm when a diluted coating solution to which ultrafine powdered tin oxide, zinc oxide, iridium oxide or the like is added is used. In this case, when the thickness is less than 0.5 μm, the antistatic property and scratch resistance are insufficient, and when it exceeds 5 μm, the light transmittance is lowered. Moreover, it is preferable that the particle size of tin oxide, zinc oxide, and iridium oxide is 0.2 μm or less. In this case, if the particle diameter is larger than 0.2 μm, the visible light is scattered, so that the transparency of the plastic substrate 2 may be lowered.

  As another surface treatment layer, for example, a hard coat layer is provided, and the hard coat layer is a dipping method, a screen printing method, a spray method, a roll coater method, a curtain flow, an unsaturated compound such as methacrylic acid or an epoxy resin in a clean environment. The surface is attached by a method, etc., and after the solvent is dried, it is crosslinked and polymerized by ultraviolet irradiation and cured in a short time. As shown in FIG. 1, the hard coat layer as the surface treatment layer 5 is preferably provided on both surfaces of the plastic substrate 2 by a dipping method or the like. In this case, when the surface treatment layer 5 is thinly applied and cured on both surfaces of the plastic substrate 2 such as an acrylic resin plate having a thickness of 1 to 5 mm, the acrylic resin plate is not distorted.

  The other hard coat layer is coated with a primer in a clean environment, dried and heat-cured, and then hard-coated and then dried and heat-cured at 80 to 130 ° C using a far infrared heater or hot air oven. Is also possible. In this case, a phosphazene resin exhibiting good abrasion resistance may be used as the coating material.

  The light diffusing layer 3 is formed on the back surface of the plastic substrate 2 and is white and opaque by containing a large amount of the silica powder 7, whereby the characters can be easily visually recognized by writing on the screen surface with an aqueous marker or the like. The light diffusion layer 3 is formed by mixing an inorganic silica powder 7 having a refractive index different from that of the transparent resin 8 and an organic plastic bead 10 and applying the mixture onto the plastic substrate 2, and the particle shape thereof is spherical. They are flat and cylindrical. The light diffusing layer 3 is preferably applied using a screen printing method, or can be applied with a roll coater or the like, or formed into a film and bonded.

  The silica powder 7 mixed in the light diffusion layer 3 has a higher refractive index of light than the transparent resin 8 and the plastic beads 10 and exists in the light path that travels straight through the thin light diffusion layer 3 to be effectively scattered. In order to increase the viewing angle, the average particle size needs to be 1.0 to 5.0 μm. Preferably, the silica powder 7 is a gel type synthetic silica having an average particle diameter of 1.0 to 3.0 μm. In this case, since the silica powder 7 is a gel type, it is water-containing non-crystalline, and the shape is more spherical, and if the average particle size is 1.0 to 3.0 μm, the plastic substrate 2 is very fine. An uneven surface can be formed, and the light diffusibility is further improved.

  The plastic beads 10 mixed in the light diffusion layer 3 generally have a refractive index difference with the transparent resin 8 of around 0.05 and an average particle size of 0.5 to 5.0 μm, which is smaller than the silica particle size 7. Cost. If the average particle size of the plastic beads 10 exceeds 5.0 μm and is larger than that of the silica particle size 7, the projection screen will become dark overall, which is not desirable. Preferably, the average particle diameter of the plastic beads 10 is 0.5 to 2.0 μm. When the plastic beads 10 are not present, a hot spot of the light source is likely to appear on the projection screen, and a speckle phenomenon in which the projection screen glares easily occurs. Usable plastic beads 10 are cross-linked polystyrene, acrylic, polyurethane beads, etc., and are preferably close-spherical cross-linked polystyrene beads that do not deteriorate the polarization property of liquid crystal. It turns yellow.

  The light diffusing layer 3 can be formed by a screen printing method, a dipping method, a spray method, a roll coater method, a curtain flow method, and the like. Particularly, when the screen printing method is used, the light diffusion layer 3 is relatively uniform and easy on a large area screen surface. Since it can adhere, it is preferable. The composition of the coating solution for the light diffusion layer is 5 to 40% by weight of silica powder and plastic beads, 20 to 40% by weight of a transparent resin, 40 to 60% by weight of a solvent, and 1 to 10% by weight of a predetermined additive. When the transparent resin is 20 to 40% by weight and the solvent is 40 to 60% by weight, an appropriate viscosity capable of screen printing can be imparted. In 5 to 40% by weight of the light diffusing agent, the breakdown is preferably 5 to 15% by weight of silica powder and 1.5 to 3% by weight of plastic beads.

  In the light diffusion layer 3, the transparent resin 8 is a polyester resin, acrylic resin, acrylic urethane resin, urethane resin, polystyrene resin, vinyl resin, or other thermoplastic resin, thermosetting resin, or reactive resin. Yes, a resin that does not impair the transparency of the light diffusion layer 3 is used. When the surface treatment layer 5 containing tin oxide, zinc oxide and iridium oxide is applied to the plastic substrate 2, the transparent resin 8 is a saturated polyester resin or polyether which is a mixture of a polyester resin and an isocyanate resin. A mixture of a resin and an isocyanate resin, a mixture of an epoxy resin and an amine resin, or an unsaturated polyester resin is used, and the saturated polyester resin is preferable in terms of surface smoothness and weather resistance. If the plastic substrate 2 is an acrylic extruded plate or cast plate without a hard coat, polyester resin, polyether resin, vinyl chloride-vinyl acetate copolymer resin, methacrylate resin, methyl methacrylate resin, cellulosic resin, urethane resin Chlorinated polypropylene resins, chlorinated polyethylene resins, cyclized rubber resins, ketone resins and modified products of these resins can be used.

  Solvents that can be used include aliphatic hydrocarbons such as mineral spirits, aromatic hydrocarbons such as solvent naphtha, Solvesso # 100, and sorbet # 150, glycols such as ethylene glycol, propylene glycol, and dipropylene glycol, butyl cellosolve, Examples include glycol derivatives such as butyl carbitol, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, and butyl carbitol acetate, and ketones such as methyl ethyl ketone, cyclohexanone, isophorone, and diacetone alcohol. Examples of the additive include an antifoaming agent, a leveling agent, a pigment dispersant, an anti-blocking agent, an anti-settling agent, an ultraviolet absorber, an ultraviolet stabilizer, and an antistatic agent. Add a small amount.

  In the light diffusion layer 3, the addition amount of the silica powder 7 is four times or more the addition amount of the plastic beads 10, and the total addition amount of the silica powder 7 and the plastic beads 10 is 0.4 to 1.5 times that of the transparent resin 10. It needs to be a quantity. If the silica powder 7 is added in an amount less than 4 times that of the plastic beads 10, the light diffusibility is lowered and the projection screen tends to become dark. Further, if the total amount of added light diffusing agent is less than 0.4 times the amount of the transparent resin 10, the light diffusibility becomes insufficient and the projection screen becomes dark. A glaring speckle phenomenon occurs.

  With respect to the plastic substrate 2, if the substrate is an acrylic resin, an ultraviolet absorber and an infrared absorber may be further added as desired. The ultraviolet absorber has a maximum absorption wavelength range of 300 to 400 nm. is there. Examples of the ultraviolet absorber include benzotriazole-based, benzophenone-based, benzoate-based, cyanoacrylate-based, and salicylate-based compounds, and benzotriazole-based compounds are particularly preferable. Benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) -benzotriazole, 2- (5-chloro-2′-hydroxy-3′-t-butyl-5′-methylphenyl) Including benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -benzotriazole, and the like, preferably the maximum absorption wavelength is light absorption near 400 nm on the high wavelength side 2- (5-Chloro-2′-hydroxy-3′-t-butyl-5′-methylphenyl) benzotriazole is used. The infrared absorber has a maximum absorption wavelength range of 650 to 900 nm. Examples of the infrared absorber include anthraquinone compounds and phthalocyanine compounds. Specifically, NQM (manufactured by Fuji Photo Film), IRF-700 (manufactured by Fuji Photo Film), IR-750 (manufactured by Nippon Kayaku), Sumisorp 200 (manufactured by Sumitomo Chemical), Sumisorp 300 (manufactured by Sumitomo Chemical) , Near infrared absorber SIR-114 (manufactured by Mitsui Toatsu Chemicals), e-excolor IR-1 (manufactured by Nippon Shokubai), xcollar 601W (manufactured by Nippon Shokubai) and the like.

  The added amount of the ultraviolet absorber is 0.005 to 2 parts by weight with respect to 100 parts by weight of the acrylic resin, and if it is less than 0.005 parts by weight, the absorption performance at a wavelength of 400 nm or less is insufficient, and 2 parts by weight is added. If exceeded, bleeding occurs from the acrylic resin. On the other hand, the addition amount of the infrared absorber and the dye or pigment is several thousand ppm or less with respect to 100 parts by weight of the acrylic resin, and the addition amount can be adjusted according to the performance and thickness of the target plastic substrate 2. That's fine. In order to mix these absorbents with an acrylic resin, it is desirable for an acrylic resin having an MFR of 0.1 or more by dissolving the desired absorbent in polymerizable monomers and performing a known cast polymerization method. The absorbent may be mixed with a super mixer or the like, and then melt-kneaded using an extruder and pelletized. The obtained acrylic resin composition can be molded into a sheet by a known molding method such as injection molding or extrusion molding.

  The transmissive screen 1 has a light transmittance of 75 to 87% by appropriately adjusting the type and amount of additives for the colored transparent plastic substrate 2, the surface treatment layer 5, and the light diffusion layer 3, and in particular, light rays. It is preferable to set the transmittance to 82 ± 3% because the reflection of external light can be further reduced while maintaining an appropriate brightness of the projection screen. A polarizing filter can be attached to the transmission screen 1 or a specific antireflection layer can be formed. Also, one side of the plastic substrate 2 may be a Fresnel lens surface or both surfaces may be the lens surface and a lenticular lens surface, or the transmission screen 1 may be used in combination with a Fresnel lens (see FIG. 5). It is also possible to use in combination.

  In the transmissive screens of FIGS. 1 to 3, the protective sheet 12 positioned on the back side is a transparent plastic material having a thickness of 1 to 2 mm, and the material is a colorless transparent plate that is the same as or different from the plastic substrate 2 of the substrate. . The protective sheet 12 is adjacent to the thin light diffusion layer 3 and serves to protect the light diffusion layer 3 from deformation and breakage. The surface 14 on the light source side of the protective sheet 12 may be subjected to anti-glare processing by emboss finishing or the like, thereby further improving the visibility of the screen by reducing the reflection of external light.

  The transmission type screen 1 is usually about 60 to 100 inches in surface dimension, and the plastic substrate 2 and the protective sheet 12 are erected in a panel form alone or attached to a metal frame or the like. Let The transmissive screen 1 is preferably attached to a gantry 15 with a caster (FIG. 4) and movable. If the surface treatment layer 5 is provided to enable writing on the screen surface, it is necessary that the plastic substrate 2 has a certain thickness so that it does not dent when writing with a water-based marker or the like. For this reason, the thickness of the plastic substrate 2 is set to 2 mm or more, and it is usually preferable to use a plastic substrate 2 having a thickness of about 5 mm in consideration of standing support, conveyance and weight.

  The projector 16 for projecting an image (FIG. 4) is generally a liquid crystal projector, for example, a projector (trade name: LP-XU33, Sanyo) equipped with a short-focus lens that shortens the projection distance to about 1.3 m on a 60-inch screen. Electric) etc. are used. In addition, a projector employing an aspherical mirror (trade name: Mirror Projector WT600J, manufactured by NEC) can shorten the projection distance to 26 cm by 60 inches, so that the laying area of the screen device is remarkably reduced, and the projector is transmissive. It can also be incorporated into the screen.

  FIG. 5 shows an example in which the transmissive screen 1 is incorporated in a projection television. In the television receiver 34, the screen 1 is vertically attached to the front surface of the receiver, and the Fresnel lens plate 36 is superposed on the rear side. Projection light emitted from a projector 38 installed upward and downward in the television receiver 34 is totally reflected by a mirror 40 at the rear of the receiver, and passes through the Fresnel lens plate 36 to project an image on the screen 1. The projector 38 may be any commercially available product, and the protective sheet 12 is unnecessary. The projection television receiver 34 is extremely easy to increase in size, such as 60 inches, and can project a clearer image than a normal cathode ray tube or liquid crystal television receiver.

  The transmissive screen according to the present invention forms a thin light diffusion layer on a colored transparent plastic substrate, and a large amount of fine silica powder is mixed into the light diffusion layer, so that a projected image is projected when projected from the back by a projector. The contrast is high and clear, and even when the number of projection pixels is high, the moire phenomenon caused by light interference does not occur. A small amount of fine plastic beads with a light refractive index lower than that of silica powder is added to this light diffusion layer, so there is no speckle phenomenon that causes the projection screen to glaring, and the hot spot of the light source is the screen. Projection screens with uniform brightness can be displayed on the entire screen.

  The transmission type screen of the present invention does not require a shaping process such as a Fresnel lens or a lenticular process, is simple in structure and has few manufacturing processes, and is inexpensive. In the transmissive screen of the present invention, fluorescent lamps or sunlight other than the visible light wavelength of the projection light source are hardly reflected from the screen surface, and as a result, the contrast of the projected image is improved. In addition, this transmissive screen has a high light transmittance for the three primary colors as a projection light source due to the colored transparent plastic substrate and the milky white light diffusion layer, so that the projected image can be easily seen without darkening the room. Is possible.

  When the transmissive screen of the present invention has a surface treatment layer, the surface treatment layer is antistatic, so dust and marker marks do not adhere during use, and even when writing with a writing instrument or the like using this surface treatment layer. The screen is not scratched. The transmission type screen of the present invention is a large-panel type whiteboard of 60 inches or more, is relatively hard and does not bend or deform, so it can be moved while attached to a frame, and does not require a special storage place. It is a large board similar to a commercial blackboard, it is easy to write on the screen, and it can also be used as a white board at educational sites.

  Next, the present invention will be described based on examples, but the present invention is not limited to the examples. FIG. 1 shows the transmissive screen 1 in an exploded manner.

  The plastic substrate 2 shown in FIG. 1 is a colored transparent acrylic extruded plate having a thickness of 5 mm, which is a methyl methacrylate homopolymer, and its size is 60 inches. This acrylic extruded plate contains several thousand ppm or less of ultrafine powder carbon black as a pigment with respect to 100 parts by weight of methacrylic resin. If desired, 0.5 parts by weight of a benzotriazole compound as an ultraviolet absorber and several hundred ppm of an anthraquinone compound as an infrared absorber may be added.

  A surface treatment layer 5 having a thickness of 1 μm is provided on both sides of this acrylic extruded plate by a dipping method. As a hard coat solution, 100 parts by weight of a resin mainly composed of urethane acrylate is added with 150 parts by weight of a conductive filler containing tin oxide and a small amount of antimony, 10 parts by weight of a dispersant, and 300 parts by weight of a solvent, and dispersed uniformly. Further, a diluted coating solution to which 500 parts by weight of a diluent solvent is added is used. The acrylic extruded plate is dipped into the diluted coating solution, then pulled up, dried at room temperature, and then cured by irradiation with ultraviolet rays.

Next, in order to form the light diffusion layer 3, a coating solution having the following composition is prepared.
Transparent resin: Saturated polyester resin 31.2% by weight
First light diffusing agent: Synthetic silica powder 11.7% by weight
Second light diffusing agent: 2.7% by weight of crosslinked polystyrene beads
First solvent: 15.6% by weight of cyclohexanone
Second solvent: Acetate type 35.7% by weight
Additives: Antifoaming agent, etc. 3.1% by weight

The saturated polyester resin is a mixture of a polyester resin and an isocyanate resin, and has a molecular weight of 15000, Tg of 65 ° C., a hydroxyl value of 6 mgKOH / g, and an acid value of 1 mgKOH / g. The synthetic silica powder is a gel-type ultrafine water-containing amorphous silicon dioxide, the average particle size is 1.9 μm (Cole counter method, AP: 30 μ), the apparent specific gravity is 0.15 g / ml, the BET ratio The surface area is 300 m ² / g and the pH is 7.01. The crosslinked polystyrene beads have a particle size of 1.3 μm and a true specific gravity of 10.5. The refractive index is 1.59.

  This coating solution is printed twice by a 250 mesh screen on the back side of the acrylic extrusion plate provided with the surface treatment layer 5 on both sides, and is dried by warm air at 70 ° C. for 30 minutes each time and cured. A light diffusion layer 3 having a thickness of 65 μm is formed on the entire screen by screen printing twice, and the light diffusion layer has a fine uneven surface. This light diffusing layer 3 has sufficient adhesion without being recognized as being peeled off by a cello tape (trade name) peel test after cross-cutting.

  Next, the light diffusion layer 3 is covered with a 2 mm thick transparent acrylic protective sheet 12 to obtain a 60-inch transmission screen 1. For example, the transmission screen 1 is attached to a frame 15 with casters 18 to be movable. The gantry 15 includes a pole 24 that stands vertically from a horizontal plate 22 to which a caster 18 is rotatably attached. When the liquid crystal projector 16 is arranged behind the transmissive screen 1 and an image is projected from the projector, a clear and high-contrast image can be seen from the observation side 26. In the transmissive screen 1, hot spots do not occur due to the light source of the liquid crystal projector 16, and the screen surface 28 does not glaring.

   The transmissive screen 1 is a large whiteboard similar to a commercially available blackboard. When the transmissive screen is arranged in a classroom or a conference room, characters are applied to the screen surface 28 by an aqueous marker while the image is not projected or while the image is projected. And a figure can be written, and this character and figure can be easily seen on a white opaque screen. The transmissive screen 1 is not damaged even when the aqueous marker contacts the screen by the surface treatment layer 5 on the surface, and the surface treatment layer is antistatic, so that characters written with the marker can be easily wiped off. it can. Since the plastic substrate 2 is relatively thick and hard, the transmissive screen 1 does not bend or deform when written on the screen, and can be used as a white board in an educational setting.

  About the acrylic extrusion board used in Example 1, the surface treatment layer 5 was provided similarly to Example 1, and the following composition range was used using the saturated polyester resin, light diffusing agent, solvent, and additive agent similar to Example 1. Adjust the coating solution. In the light diffusing agent, the silica powder 7 has an average particle diameter of 1.5 μm, and the crosslinked polystyrene beads 10 have an average particle diameter of 1.3 μm.

Light diffusing agent 12.0% by weight
Saturated polyester resin 30-40% by weight
10-20% by weight of cyclohexanone
Acetate solvent 30-40% by weight
Additive: 1-5% by weight

  For the light diffusing agent, the mixing ratio of the silica powder 7 and the cross-linked polystyrene beads 10 is set to 10: 3, 10: 6, 10: 9, 13: 3, 13: 6 or 13: 9, and coating solutions are prepared respectively. Each coating solution is printed twice on the back side of the acrylic extruded plate with a 250 mesh screen, and is dried by warm air at 70 ° C. for 30 minutes each time. The light diffusing layer 3 is formed on the entire screen by screen printing twice, and the light diffusing layer has a fine uneven surface.

  The mixing ratio of the silica powder 7 and the cross-linked polystyrene beads 10 is most preferably 13: 3 from the viewpoint of the brightness of the projection screen, and the light diffusibility is slightly reduced at 10: 3, and 10: 6, 10: 9, 13 : 6 and 13: 9 are not preferable because the light diffusibility decreases and the projection screen becomes dark. In addition, the formed light diffusion layer has sufficient adhesion because no peeling was observed in the cello tape (trade name) peel test after cross-cutting at any mixing ratio.

  In the same manner as in Example 1, for the light diffusion layer 3 in which the mixing ratio of the silica powder 7 and the crosslinked polystyrene beads 10 is 13: 3, the light diffusion layer is covered with a transparent acrylic protective sheet 12, and the transmission type screen 1 is formed. obtain. The obtained transmissive screen 1 does not generate a hot spot due to the light source of the liquid crystal projector or a speckle phenomenon in which the screen surface glares.

  In FIG. 2, the transmissive screen 6 uses the same plastic substrate 2 of an acrylic extruded plate as in Example 1, but the acrylic extruded plate is not provided with a surface treatment layer. In order to produce a coating solution for the light diffusion layer 3, a methacrylate resin is used as the transparent resin, and the light diffusion layer 3 is formed by processing in the same manner as in Example 1 except for this. This light diffusing layer 3 has sufficient adhesion without being recognized as being peeled off by a cello tape (trade name) peel test after cross-cutting.

  As in Example 1, the light diffusion layer 3 is covered with a transparent acrylic protective sheet 12 to obtain a 60-inch transmission screen 6. The obtained transmissive screen 6 does not generate a hot spot due to the light source of the liquid crystal projector or a speckle phenomenon in which the screen surface glares.

  The transmissive screen 6 is easy to convey and stand because the plastic substrate 2 is relatively thick and hard. Since the surface of the transmissive screen 6 does not have an antistatic surface treatment layer, it is necessary to be careful not to damage the screen surface during use because dust and dust are slightly attached thereto.

  In FIG. 3, the transmission type screen 30 uses the same plastic substrate 2 of an acrylic extruded plate as in Example 1, and on the surface of the acrylic extruded plate, trimethylolpropane triacrylate, pentaerythritol, 2-hydroxyethyl acrylate, A coating solution containing benzoisobutyl ether is applied by a roll coater and irradiated with ultraviolet rays for 30 minutes to cure the coating film. The surface treatment layer 5 obtained has a thickness of 3 μm.

  As the light diffusion layer 3, a coating solution is prepared by setting the mixing ratio of silica powder and crosslinked polystyrene beads to 13: 3, as in Example 2. This coating solution is printed twice on the back surface of the acrylic extruded plate by a 250 mesh screen, and is dried by warm air at 70 ° C. for 30 minutes each time and cured. The light diffusion layer 3 is formed on the entire screen by screen printing twice, and the light diffusion layer has a fine uneven surface. This light diffusing layer 3 has sufficient adhesion without being recognized as being peeled off by a cello tape (trade name) peel test after cross-cutting.

  Similar to Example 1, the light diffusing layer 3 is covered with a transparent acrylic protective sheet 12 to obtain a transmission screen 30. The obtained transmissive screen 30 does not generate a hot spot due to the light source of the liquid crystal projector or a speckle phenomenon in which the screen surface glares.

  A transmissive screen is produced by processing in the same manner as in Example 1 except that an acrylic cast plate is used instead of the acrylic extruded plate as the plastic substrate. Although the acrylic cast plate lacks some surface smoothness compared to the acrylic extruded plate, the obtained transmissive screen has hot spots or glare on the screen surface due to the light source of the liquid crystal projector, as in Example 1. Speckle phenomenon does not occur.

It is a schematic side view which expands and shows the transmission type screen which concerns on this invention. It is a schematic side view which expands and shows the modification of this invention. It is a schematic side view which expands and shows another modification of this invention. It is a schematic side view which shows the transmission type screen attached to the mount frame. It is a schematic side view which shows the other usage example of a transmission type screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission type screen 2 Plastic base material 3 Light diffusion layer 5 Surface treatment layer 7 Silica powder 8 Transparent resin 10 Plastic bead

Claims (7)

  It consists of a colored transparent plastic substrate and a milky white light diffusing layer having fine irregularities formed on the back surface of the substrate, and the light diffusing layer has an average particle size of 1.0 to 1.0 mixed in the transparent resin. It is constituted by 5.0 μm silica powder and plastic beads having an average particle size of 0.5 to 5.0 μm smaller than the silica particle size, and the addition amount of silica powder is more than 4 times the addition amount of plastic beads, A transmissive screen in which the total amount of silica powder and plastic beads is 0.4 to 1.5 times the amount of transparent resin.   A colored transparent plastic substrate, an antistatic surface treatment layer formed and cured on at least one side of the substrate, and a fine surface formed on the substrate or the surface treatment layer on the back surface of the plastic substrate It comprises a milky white light diffusing layer having an uneven surface, and the light diffusing layer comprises silica powder having an average particle size of 1.0 to 5.0 μm mixed in a transparent resin, and an average particle size of 0 smaller than the silica particle size. A transmission type screen composed of .5 to 5.0 .mu.m plastic beads, wherein the total addition amount of silica powder and plastic beads is 0.4 to 1.5 times the amount of transparent resin.   3. The screen according to claim 1, wherein the silica powder is a gel type synthetic silica having an average particle diameter of 1.0 to 3.0 [mu] m.   The screen according to claim 1 or 2, wherein the plastic beads are crosslinked polystyrene, acrylic or polyurethane beads having an average particle diameter of 0.5 to 2.0 µm.   At least one side of a tinted colored transparent plastic substrate is cured by applying a thin layer of surface treatment layer by vapor deposition, coating, transfer or dipping, etc., and then surface treatment of the milky white light diffusion layer by screen printing The manufacturing method of printing on the layer to a thickness of 5 to 50 μm, and the composition of the coating solution of this light diffusion layer is 5 to 40% by weight of silica powder and plastic beads, 20 to 40% by weight of transparent resin, solvent 40 to 60% by weight, predetermined additive 1 to 10% by weight, and the amount of silica powder added is very large, such as 0.4 to 1.5 times the amount of transparent resin in the light diffusion layer. A method for manufacturing a transmission screen in which fine irregularities are formed on the entire surface of the screen.   6. The production according to claim 5, wherein the plastic substrate is an acrylic resin plate having a thickness of 1 to 5 mm, and the acrylic resin plate is not distorted by providing a thin surface treatment layer on both sides of the acrylic resin plate and curing it. Law.   The surface treatment layer has an antistatic property by containing ultrafine powdered tin oxide, zinc oxide, and iridium oxide having a thickness of 0.5 to 5 μm and a particle size of 0.2 μm or less. The method according to claim 5 or 6, wherein the method has scratch resistance and at the same time maintains high light transmittance.

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