JP2013210515A - Projection screen and whiteboard device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection screen capable of obtaining clear projection images without generating hot spot owing to a sufficient light diffusion reflectivity even when a high luminance projector is used, and to provide a whiteboard device using the same ensuring sufficient erasing feature using an eraser.SOLUTION: A projection surface has an exposed surface of a coating layer formed on the surface of a base member. The base member has a rough surface formed with irregularities with plural particles of titanium oxide in the boundary of the coating layer and the base member. In the particles of the titanium oxide: the mean particle diameter is 0.1-0.5 μm; and content is 3-20wt%. With this, a sufficient light diffusion reflectivity is obtained at the surface of the base member. Thus, the glossiness on the projection surface (entire glossiness) is reduced and clear projection images are obtained without generating any hot spot even when a high luminance projector is used.

Description

  The present invention relates to a projection screen on which a marker can be written and erased with a marker and a whiteboard device using the same.

  2. Description of the Related Art In recent years, a whiteboard device that can project data from a projector device connected to a personal computer or the like and can perform writing and erasing with a whiteboard marker has been used.

  This type of whiteboard device has a screen that is surface-treated to diffusely reflect the projection light from the projector in order to make the projection surface easy to see. As a projection screen suitable for this type of whiteboard, Patent Document 1 discloses a whiteboard and a projection screen combined film that can be used as a whiteboard and also as a projection screen. Specifically, the surface of the white synthetic resin film is made a fine uneven surface so that the surface gloss is reduced and the projection surface can be written and erased with a marker, and the hard hard coat layer is formed on the fine uneven surface. Are coated.

  Since the film having such a structure is a fine uneven surface, the film has excellent light diffuse reflectance, and a clear projected image can be obtained. However, when used as a whiteboard, the marker ink remains in the fine recesses on the surface, and it is difficult to cleanly erase the written data on the whiteboard. As a result, there is a problem that the whiteboard becomes dirty due to the accumulation of ink that cannot be completely wiped off during repeated use, making it unusable.

  In order to improve the erasability, the surface irregularities may be made flatter. For example, the writing sheet disclosed in Patent Document 2 includes a surface clear layer having an unevenness by embossing, a base film layer, and an adhesive layer. Since the sheet embossed in this way does not have a fine uneven surface like the film disclosed in the above-mentioned Patent Document 1, the erasability is improved. And if the unevenness | corrugation of the surface was formed moderately, in the conventional projector apparatus, it was able to improve also about anti-glare property.

JP 11-277984 A JP 2010-046961 A

  However, in recent years, the light source of the projector apparatus has become highly bright. With the previous projector device, it was difficult to see the projected image without turning off the lighting in the venue. On the other hand, if a projector device with high brightness in recent years is used, a projected image can be comfortably viewed without particularly turning off the lighting in the venue. When this happens, a phenomenon in which the light source of the projector appears as a bright spot at the center of the projected image, a so-called hot spot occurs, and the projectability deteriorates. Even if there is no problem with anti-glare properties in the case of a projector device that can only project at a low brightness before, even higher anti-glare properties are required for projector devices with high brightness.

  As described above, when the surface of the whiteboard is used as a projection surface, it is necessary not only to ensure good erasability of marker ink by an eraser, but also to provide a high level of anti-glare property for a high-brightness projector device. Must be realized.

  The present invention is for solving the above-described conventional problems, has a diffuse reflection property of light suitable for projection, and can obtain a clear projection image that does not cause a hot spot. For projection that has sufficient light diffusibility for the device, can produce clear projected images that do not cause hot spots, and can write on the projection surface using markers and erase marker ink An object is to provide a screen and a whiteboard device using the same.

  In order to achieve the above object, the present invention includes a base material and a coating film layer formed on the surface of the base material, the coating layer being an exposed surface opposite to the surface in contact with the base material. The substrate has a plurality of particles of titanium oxide having an average particle diameter of 0.1 to 0.5 μm and a content of 3 to 20 wt%, and the coating of the substrate In the contact surface with the film layer, a base roughening surface having irregularities is formed by a plurality of particles of the titanium oxide.

  The present invention performs diffuse reflection of light on the surface of the base material by applying a so-called “base roughening treatment” in which irregularities are formed on the surface of the base material, which is a contact surface with the coating layer serving as a projection surface. Therefore, the glossiness (overall glossiness) on the projection surface can be reduced. As a result, even for a high-brightness projector apparatus, it is possible to obtain a clear projected image in which the light source of the projector appears as a bright spot in the center of the projected image, that is, a so-called hot spot does not occur. It is also possible to provide a projection screen capable of writing and erasing markers on the projection surface and a whiteboard device using the projection screen.

1 is a schematic configuration diagram of a whiteboard device according to an embodiment of the present invention. Schematic which shows the cross-sectional structure of the projection screen in one Example of this invention. The flowchart which shows the manufacturing process of the projection screen of this invention (A) Main part enlarged sectional view showing base treatment of substrate, (b) Main part enlarged sectional view after lamination of coating film layer, (c) Main part enlarged sectional view after solvent removal of coating film layer, ( d) Enlarged sectional view of the main part after the screen surface is formed (A) Photo before sandblasting of the polyester film surface, (b) Photo after sandblasting Photo after sandblasting of the polyester film surface (A) Photo after sandblasting of the polyester film surface, (b) Photo after sandblasting of the polyester film surface Photograph of the surface of white PET base material before sandblasting Schematic enlarged cross-sectional view of the main part of a base material containing titanium oxide fine particles The figure which shows the change of base glossiness when the average particle diameter and content rate of titanium oxide are changed Flow chart showing the manufacturing process in the sandblasting treatment of the substrate The figure corresponding to FIG. 10 which shows the change of the foundation | substrate glossiness after performing the sandblasting process of the base material containing titanium oxide microparticles | fine-particles

  1st invention made | formed in order to solve the said subject, The coating-film layer by which the exposed surface on the opposite side to the surface which is formed in the surface of the said base material and contacts the said base material becomes a projection surface, The base material has a plurality of particles of titanium oxide having an average particle diameter of 0.1 to 0.5 μm and a content of 3 to 20 wt%, It is set as the structure by which the base roughening surface which has an unevenness | corrugation was formed by the several particle | grains of the said titanium oxide in the contact surface with the said coating-film layer of material.

  According to this, diffuse reflection of light on the surface of the substrate is performed by applying a so-called “surface roughening treatment” that forms irregularities on the surface of the substrate that is the contact surface with the coating layer that becomes the projection surface. Therefore, the glossiness (overall glossiness) on the projection surface can be reduced. As a result, even for a high-brightness projector apparatus, it is possible to obtain a clear projected image in which the light source of the projector appears as a bright spot in the center of the projected image, that is, a so-called hot spot does not occur. It is also possible to provide a projection screen capable of writing and erasing markers on the projection surface and a whiteboard device using the projection screen.

  According to a second aspect of the present invention, in the first aspect of the present invention, the unevenness of the base roughening surface is defined by a 60 ° specular gloss, and the range is 1 to 65.

  Since the unevenness of the surface roughening surface affects the glossiness of the surface (projection surface) of the coating film layer, the surface roughness of the surface roughening surface is set to a range of 1 to 65 with a 60 ° specular glossiness. The glossiness of the surface does not lose the antiglare property, and the glossiness of the surface of the coating layer can be lowered.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the base roughening surface further has a concavo-convex shape obtained by sandblasting.

  According to this, the unevenness of the roughening surface of the base can be formed by combining the one formed by the fine particles of titanium oxide and the one formed by sandblasting, and the glossiness of the roughening surface (the surface of the base material) It is possible to easily set the diffuse reflectance of light. Therefore, even a high-brightness projector apparatus can have sufficient diffused light reflectivity as a projection screen, and light diffused reflectivity to such an extent that hot spots by the projector are not noticeable can be ensured.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the 60 ° specular glossiness of the exposed surface is set to 40 or less.

  When the 60 ° specular glossiness on the exposed surface of the coating layer that is the overall glossiness is high, there is a possibility that sufficient performance cannot be obtained for the antiglare property, so the overall 60 ° specular glossiness is 40. By setting it as the following, the glare-proof property with respect to a high-intensity projector apparatus can be ensured.

  According to a fifth aspect of the present invention, a board surface on which writing erasure is performed is formed by the projection screen according to any one of the first to fourth aspects. Thereby, a practically excellent whiteboard device capable of obtaining the above-described effect can be obtained.

  Hereinafter, an embodiment of the projection screen of the present invention and a whiteboard device using the same will be described in detail.

  FIG. 1 is a schematic configuration diagram of a whiteboard device according to an embodiment of the present invention. The whiteboard device main body 1 has a board surface 2 on which a surface layer is formed by the projection screen of the present invention. The board surface 2 has an appropriateness as a projector screen for projecting a projected image from the projector device 4 connected to the personal computer 3 or the like, and has an appropriateness for erasing writing using the whiteboard marker 5 and the eraser 6. Next, the projection screen of the present invention will be described.

  FIG. 2 is a schematic diagram showing a cross-sectional configuration of a projection screen in one embodiment of the present invention. The base material 7 has a strength that does not hinder the formation and holding of a coating layer 10 composed of spherical fine particles 8 and a matrix resin 9 described later, and use as a whiteboard surface. However, in this base material 7, by applying a so-called “base roughening treatment” to the coated surface of the base material on which the coating film layer is formed and providing the base roughening surface layer 11, the glossiness of the entire projection screen is increased. I try to lower it. This point will be described in detail later.

  Examples of the material of the base material 7 include plastic, steel plate, wood plate, glass plate, and resin decorative plate. The thickness of the substrate is not particularly limited, and a film-like or plate-like material can be used in accordance with the configuration of the whiteboard device and the board surface manufacturing method. In particular, when a sheet-like projection screen is manufactured, a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, a polyvinyl chloride film, a polycarbonate film, or the like having a thickness of about 20 to 200 μm is preferably used. be able to.

  When the base material 7 uses a transparent material for the coating layer 10, it also functions as a reflection layer for projection light transmitted through the coating layer 10 and a layer for determining the color of the board surface. It is preferably white or a light color close to white. Alternatively, a light reflecting layer (not shown) may be separately formed on the surface (back surface) opposite to the surface on which the coating film layer 10 is formed using a colorless or highly transparent material as the base material 7. . In this case, the light reflecting layer can be formed by a method such as painting with a white ink or pasting another light reflecting film material. When the board surface 2 of the whiteboard device main body 1 is formed, when the plate-like base material 7 is used, it can be used as it is, for example, when the film-like base material 7 is used. In addition, it is possible to separately form the back surface by bonding with a highly rigid plate member.

  The coating layer 10 is configured in such a manner that spherical fine particles 8 and additives 12 to be described later are included in a matrix resin 9, and the upper surface (upper side in the figure) of the spherical fine particles 8 coated with the matrix resin 9 and a matrix filling the space therebetween. The resin 9 forms smooth surface irregularities having dimensions and shapes as described below, which is a feature of the present invention. The thickness of the coating layer 10 is not particularly limited as long as surface irregularities having the dimensions and shapes as described below can be formed using a combination of the matrix resin 9 and the spherical fine particles 8 and a construction method, but the thickness is about 3 to 30 μm. This is the preferred range. Moreover, in order to ensure the strength and durability as a white board surface, it is preferable to have a surface hardness of B or higher in pencil hardness.

  The spherical fine particles 8 have smooth irregularities having dimensions and shapes as described below on the surface 10a as an exposed surface opposite to the surface in contact with the substrate 7 of the coating layer 10 by combination with the matrix resin 9. Blend to form. The spherical fine particles 8 are preferably transparent or white in consideration of light reflectivity and influence on the color of the board surface.

  In a projection screen in a conventional whiteboard device, fine particles having a random shape and a relatively small particle size, such as pulverized silica, are often used. When such fine particles are used, the uneven shape tends to be finer and irregular, so that it is easy to form a surface shape with high diffuse reflectivity and excellent projector projection, and is advantageous in terms of raw material costs, etc. There are advantages. However, uneven shapes having fine and sharp curves are likely to occur, and the interface between fine particles having a complicated shape and the resin may be exposed and formed on the surface 10a. In many cases, the marker ink cannot be completely wiped off by an eraser, and it is difficult to ensure sufficient marker writing erasability.

 For this reason, in the present invention, it is preferable to use substantially spherical fine particles in order to form irregularities with a smoother curve and to achieve both good projector projection and writing erasure with a marker. In order to form an uneven surface having a dimension and shape as described later, it is preferable to use substantially spherical fine particles having an average particle diameter of 3 to 30 μm, preferably 5 to 20 μm. The average particle diameter referred to here is a volume average diameter and is measured using a Coulter counter (manufactured by Coulter). When the average particle size is smaller than 3 μm or larger than 30 μm, it becomes difficult to form a concavo-convex shape having a size range as described later, and good projection and writing erasability cannot be achieved at the same time. As the spherical fine particles 8, various glass beads, spherical silica fine particles, spherical alumina fine particles, spherical resin fine particles and the like used for resin filling and surface treatment can be used.

  Examples of glass beads include spherical glass beads using soda lime glass or low alkali glass. Examples of commercially available products include glass beads for fillers manufactured by Potters Ballotini Co., Ltd. (Product name) series. Examples of spherical silica fine particles include spherical fused silica fine particles and spherical synthetic silica fine particles. Examples of commercially available products include Excelica (trade name) series manufactured by Tokuyama Corporation, and high-purity true spherical silica manufactured by Tatsumori Co., Ltd. There is a fused silica spherical type manufactured by Denki Kagaku Kogyo Co., Ltd. Examples of commercially available spherical alumina fine particles include spherical alumina manufactured by Denki Kagaku Kogyo Co., Ltd., Aruna Beads (trade name) manufactured by Showa Denko KK, Admafine (trade name) manufactured by Admatechs Co., Ltd., and manufactured by Micron Co., Ltd. There are spherical alumina particles. Examples of spherical resin fine particles include spherical acrylic resin fine particles, spherical polystyrene fine particles, spherical polyacrylonitrile fine particles, and spherical nylon fine particles. Examples of commercially available products include Chemisnow (trade name) series manufactured by Soken Chemical Co., Ltd., Toyo There are Tuftic (trade name) series manufactured by Spinning Co., Ltd., Flow Beads (trade name) series manufactured by Sumitomo Seika, and Techpolymer (trade name) series manufactured by Sekisui Plastics Co., Ltd.

  Among the spherical fine particles as described above, the spherical resin fine particles have a smooth surface, a uniform shape, physical properties such as specific gravity and thermal expansion coefficient, and chemical properties of the particle surface. Since it is advantageous in forming the coating layer 10 by a combination with the matrix resin 9 described later, it can be used particularly preferably in the present invention.

  The matrix resin 9 encloses the spherical fine particles 8 to form smooth irregularities having dimensions and shapes as will be described later, and controls the physical and chemical properties of the outermost surface of the projection screen. Therefore, (1) a coating film can be formed on the base material 7 by itself or by mixing with a solvent, and (2) the average particle diameter of the resin fine particles 8 and the coating film layer 10 while coating the surface of the spherical fine particles 8. It is possible to form a desired concavo-convex shape by adjusting the mixing ratio in the inside, (3) It is possible to form a coating layer 10 having sufficient strength and durability as a surface layer of a projection screen, (4) It is necessary to have basic performance such as moderate affinity for the marker ink, interfacial tension, and (5) transparency or light color. As long as this requirement is satisfied, the matrix resin 9 is not particularly limited, and various known paint resins and coating resins can be used. Examples of such paint resins and coating resins include acrylic resins, epoxy resins, urethane resins, polyolefin resins, silicon resins, fluorine resins, vinyl chloride resins, alkyd resins, melamine resins, and the like. There are various modified products and copolymer resins, and a wide variety of products are on the market.

  As a method of forming a film of these resins on a substrate, for example, (1) using a reactive resin raw material mixture containing an ultraviolet curable, electron beam curable or thermosetting monomer, oligomer, resin, etc. A method of curing a resin raw material by light or heat after coating to form a coating film. (2) After coating on a substrate in a state where the resin is dissolved or dispersed in a solvent, the coating film is formed by volatilizing the solvent. There is a method of forming, and (3) a method of forming a thermoplastic resin into a sheet by extrusion molding or the like. Among these, the method using an ultraviolet curable resin is suitable for forming the matrix resin 9 having the basic performance as described above, and there are many choices of raw materials, and it is easy to adjust the physical properties of the raw material mixture. In terms of productivity, the resin curing reaction is completed in a short time, which is advantageous and particularly preferable.

  From the above viewpoints, UV curing based on monomers, oligomers, and resins whose main components are acrylic, epoxy, and modified or copolymerized compounds thereof is particularly preferable as a raw material for the matrix resin 9. Mold resin. Such UV curable resin raw materials such as epoxy acrylate, urethane acrylate, epoxy resin, and various monomers are, for example, Negami Industrial Co., Ltd., Shin-Nakamura Chemical Co., Ltd., Kyoeisha Chemical Co., Ltd., Sartomer Japan Co., Ltd., Toagosei Co., Ltd. The company is marketed by Nippon Kayaku Co., Ltd.

  Usually, when producing an ultraviolet curable resin, it is necessary to mix | blend a photoinitiator in addition to the said monomer, oligomer, resin, etc. Examples of the photopolymerization initiator include radical polymerization initiators such as alkylphenone and acylphosphine oxides, and cationic polymerization initiators such as iodonium salt and sulfonium salt. Examples of commercially available products include Ciba Specialty.・ IRGACURE (trade name) series made by Chemicals Co., Ltd., DAROCURE (trade name) series, KAYACURE (trade name) series made by Nippon Kayaku Co., Ltd., Sun Aid SI (trade name) series made by Sanshin Chemical Industry Co., Ltd. is there.

  In addition to the surface adjusting additive 12 for adjusting the interfacial tension and slipperiness of the surface, a dispersant for improving the dispersibility of the spherical fine particles 8, a coloring material for coloring the matrix resin 9, etc. It is possible to mix | blend suitably. Further, in order to facilitate the mixing with the spherical fine particles 8 and the coating process, the viscosity of the resin solution may be adjusted by mixing a volatile organic solvent. In this case, the raw material mixture is applied onto the substrate 7. Then, before performing ultraviolet irradiation, it is necessary to remove the volatile organic solvent by heat treatment or the like. Examples of suitable volatile organic solvents are ethyl acetate, isopropyl acetate, butyl acetate, methyl isobutyl ketone, methyl ethyl ketone, isopropyl alcohol. The additive 12 is slippery by reducing the surface tension of the coating layer 10 through the drying process, increasing the water / oil repellency of the coating layer 10 after drying, and reducing the friction coefficient of the surface. The effect which raises is expressed. Thereby, the writing / erasing property of the marker, particularly the erasing property is improved. The additive 12 is a liquid compound (polymer). In FIG. 2, for convenience, the additive 12 is shown in the form of particles. However, the additive 12 is actually dissolved in the matrix resin 9 at the molecular level and has a size as shown in FIG. It does not exist as a particle.

  Various ultraviolet curable resin raw material mixtures prepared for paints and coatings are commercially available on the basis of the above-described blending and can be suitably used in the present invention. Examples of commercially available products include Shigamine (trade name) series manufactured by Nippon Synthetic Chemical Co., Ltd., Adekaoptomer (trade name) series manufactured by ADEKA Co., Ltd., Beam Set (trade name) series manufactured by Arakawa Chemical Industries, Ltd., There is DIC Corporation's Unidick (trade name) series.

  Using the above-described constituent materials, the projection screen of the present invention can be produced by the following manufacturing process.

  Each measurement parameter regarding the uneven shape of the surface 10a of the coating layer 10 is defined in JIS B 0601: 2001. The surface coating layer is formed with the material structure as described above, and the arithmetic average roughness Ra specified in JIS B 0601: 2001 is in the range of 0.3 ≦ Ra ≦ 4 (μm), and JIS B The surface unevenness shape is such that a value Sm / Ra obtained by dividing the average peak interval Sm (μm) defined in 0601: 2001 by the arithmetic average roughness Ra is in a range of approximately 30 ≦ Sm / Ra ≦ 150. Thus, it is possible to secure the marker ink wiping property and a certain degree of light diffusion reflectivity.

  When the arithmetic average roughness Ra becomes 0.3 (μm) or less, the glossiness of the surface 10a of the coating layer 10 rapidly increases, and the 60 ° specular glossiness (based on JIS Z 8741 described later) becomes 40 or less. Difficult to do. Further, when the arithmetic average roughness Ra is 4 or more, the wear of the marker whose tip is made of felt is accelerated. When the writing is erased about 50 times, the tip of the marker may be worn out and may not be written. Moreover, since the unevenness | corrugation of the surface 10a of the coating film layer 10 becomes large, erasure | elimination of the marker ink written on the surface 10a of the coating film layer 10 becomes difficult.

  The value of Sm / Ra is most preferably about 70. On the other hand, when Sm / Ra is 150 or more, the light diffusion reflectivity becomes too small, and a hot spot is generated, so that the projectability is deteriorated. On the other hand, when Sm / Ra is 30 or less, the erasability of the marker ink decreases.

  In order to form the unevenness as described above, as described above, the coating layer 10 formed on the coating surface of the base material 7, that is, the base roughening surface layer 11, forms unevenness on the surface layer. Many spherical fine particles 8 and additives 12 are included.

  As shown in FIG. 2, the light (arrow L) incident from the surface 10 a of the coating layer 10, that is, the writing surface, is reflected by the primary reflected light (arrow L <b> 1) reflected by the surface 10 a of the coating layer 10. Secondary reflected light (arrow) that is transmitted through the film layer 10, reflected by the coating surface of the base material 7 (that is, the contact surface with the coating film layer 10 of the base material 7), and transmitted again through the coating film layer 10. And L2).

  Since the unevenness as described above is formed on the surface 10a of the coating layer 10, the primary reflected light (L1) is not completely specularly reflected but is diffused to some extent. At the same time, the light incident on the inside of the coating layer 10 is also diffused to some extent. In the coating layer 10, the spherical fine particles 8, the additive 12, and the matrix resin 9 that covers them are made of different materials and therefore have different light refractive indexes. Therefore, refraction and scattering of the secondary reflected light (L2) occur at the interface among the spherical fine particles 8, the additive 12, and the matrix resin 9. The secondary reflected light (L2) thus refracted and scattered is further diffused by the unevenness when emitted from the surface 10a of the coating layer 10. In this way, the primary reflected light (L1) and the secondary reflected light (L2) are diffused in double, triple or more, so that the light source of the projector looks like a bright spot in the center of the projected image. It is possible to reduce the phenomenon, the occurrence of so-called hot spots.

  However, sufficient light diffusivity is ensured only by the unevenness on the exposed surface of the coating layer 10 and the refraction / scattering of light at the interfaces between the spherical fine particles 8, the additive 12, and the matrix resin 9. You may not be able to. In particular, in recent years, since the light source of the projector apparatus has become brighter, the projected image can be comfortably viewed without turning off the lighting in the venue. When this happens, a phenomenon in which the light source of the projector appears as a bright spot at the center of the projected image, a so-called hot spot occurs, and the projectability deteriorates. Even if there is no problem with anti-glare properties in the case of a projector device that projects only at a low luminance before, even higher anti-glare properties are required for projector devices with high luminance.

  Therefore, in the projection screen of the present invention, the so-called “undercoat” is applied to the coated surface (that is, the contact surface of the base material 7 with the coating layer 10), which is the surface on which the coating layer 10 of the base material 7 is formed. "Trolling treatment". In the illustrated example, as shown in FIG. 2, a base roughening surface layer 11 having a fine uneven shape is formed on the coated surface of the base material 7. This “base roughening treatment” is performed by sandblasting, mat coating using pigments and fine particles such as titanium oxide and calcium carbonate, and the like. Which of these methods is selected is determined by the material of the base material 7 and the glossiness of the surface roughening surface layer 11 to be formed. In addition, when the sandblasting process is selected, the base glossiness can be changed by adjusting the particle size, the number, the shape, the applying speed, etc. of the sand applied to the surface of the base material 7 to which the base roughening process is applied. .

  The surface roughening surface layer 11 in FIG. 2 is described as a completely different layer from the base material 7, but this is a case of mat coating. When mat coating is selected, the base glossiness can be changed by changing the particle size or content of titanium oxide or calcium carbonate, as will be described later. In the case of a method of processing the surface of the base material 7 such as sandblasting, the base material 7 and the surface roughening surface layer 11 are naturally integrated. In any case, in FIG. 2, a boundary line is described between the base material 7 and the base material 7 in order to easily recognize the presence of the base roughening surface layer 11.

  By forming such a surface roughening surface layer 11, the secondary reflected light that passes through the coating layer 10 and is reflected on the surface roughening surface layer 11 of the substrate 7 is further diffused. That is, the light diffuse reflectance is further increased. Therefore, even in a high-brightness projector apparatus, a clear projected image that does not cause a hot spot can be obtained.

  The projection screen of the present invention can be manufactured by using various known resin mixing methods and coating methods according to the material structure as described above, and an example of the manufacturing method will be described below. .

  FIG. 3 is a flowchart showing the production process of the projection screen of the present invention, and FIG. 4 is a diagram showing the screen surface forming process accompanying the process of the flowchart of FIG. First, an ultraviolet curable coating solution is formed for applying the coating surface of the substrate 7 to form irregularities (step ST1-1). At this time, first, an ultraviolet curable resin solution mainly composed of urethane acrylate or epoxy acrylate is prepared. At this time, it is preferable that an appropriate amount of a volatile organic solvent is mixed to adjust the solution viscosity to be suitable for coating. Here, various known mixers, shakers and the like can be used for mixing the resins. Subsequently, spherical acrylic resin fine particles 8 having a predetermined average particle diameter and an additive 12 for obtaining the slipperiness and oil repellency of the marker are mixed in the ultraviolet curable resin solution. As described above, the average particle diameter referred to here is a volume average diameter, and is measured using a Coulter counter (manufactured by Coulter). In addition, various well-known mixers, shakers, etc. can be used for mixing. In this way, a coating stock solution is obtained.

  In parallel with or before and after this, a so-called “base roughening treatment” is performed on the coated surface of the base material 7 (that is, the contact surface of the base roughening surface layer 11 with the coating layer 10) to form a base having irregularities. A roughening surface 11a is formed (step ST1-2, FIG. 4A). As described above, this “base roughening treatment” is performed by sandblasting or mat coating. Which of these methods is selected depends on the material of the base material 7 and the glossiness of the surface roughening surface layer 11 to be formed. 4A is an example of the mat coating shown in FIG. 2, and the same reference numerals are given to the same parts as those in FIG. 2, and the detailed description thereof is omitted.

  The coating undiluted solution 21 produced in step ST1-1 is applied to the coated surface (base roughening surface 11a) of the base material 7 made of white PET subjected to the base roughening treatment in this way (step ST1). ST2, FIG. 4 (b)). A known coating apparatus such as a roll coater, a bar coater, or a gravure coater can be used for applying the coating stock solution 21. Subsequently, the substrate after coating is heated in an oven or the like to evaporate the volatile organic solvent (step ST3, FIG. 4C). Here, when a volatile organic solvent as exemplified above is used, for example, heat drying may be performed under conditions of 80 ° C. and several minutes. At this time, with the evaporation of the volatile organic solvent, the surface irregularities as described above are almost formed.

Furthermore, a coating layer is formed by irradiating ultraviolet rays from above in the drawing onto the uneven surface 21a of the uneven surface after the volatile organic solvent of the coating stock solution 21 is evaporated to cure the ultraviolet curable resin. 10 is completed (step ST4, FIG. 4D). At this time, the ultraviolet curable resin is slightly shrunk due to curing shrinkage accompanying the polymerization reaction. Various known ultraviolet light source devices can be used for ultraviolet irradiation, such as a metal halide lamp, a mercury lamp, a xenon lamp, and an LED lamp. In the case of a general urethane acrylate resin, the amount of ultraviolet rays may be such that the integrated light quantity measured at a wavelength of 365 nm is about 100 to 2000 mJ / cm ² .

  With the material structure and method described above, the diffuse reflectance of light on the surface 10a of the coating layer 10 and the surface roughening surface 11a is further improved, so even in a high-brightness projector device, a projector is provided at the center of the projected image. A projection screen capable of writing or erasing a marker on a projection surface and a whiteboard device using the same can obtain a clear projection image that does not cause a phenomenon that the light source of the light source appears as a bright spot, that is, a so-called hot spot Can be provided.

  2 is not limited to the method mainly using the spherical fine particles 8 and the matrix resin 9 described above. For example, other generally known unevenness forming methods such as by embossing or other embossing may be used.

Examples of the present invention will be described below using Table 1 and FIG. 2 together. In the following examples, the arithmetic average roughness and the average crest interval indicate values measured according to JIS-B-0601 as described above. Further, the “glossiness” is measured by a specular glossiness-measuring method defined in JIS Z 8741 using a glossiness meter (manufactured by HORIBA, Ltd.) having an LED light source and a silicon photodiode photodiode. 60 ° specular gloss. Hereinafter, it is referred to as “glossiness”.
(Relationship between substrate glossiness and surface glossiness / marker writing erasability)
[Example 1 (sample number 3)]

  A white polyester film (Mitsubishi Resin: Diafoil W-200, glossiness 99) having a thickness of 125 μm was used as the substrate 7 (see FIG. 2). Then, the surface (one surface) was subjected to a sand blasting process as a base roughening process so that the glossiness was 3 (step ST1-2 in the previous FIG. 3). A photograph of the polyester film surface in this step before sandblasting is shown in FIG. 5 (a), and a photograph after sandblasting is shown in FIG. 5 (b).

  In that state, the coating stock solution prepared by the method described in step ST1-1 in FIG. 3 was applied (step ST2 in FIG. 3), and the solvent was removed by heat drying (previous diagram). Step ST3 in 3). At this time, the average particle diameter of the spherical fine particles contained in the coating stock solution was 10 μm. As described above, the average particle diameter referred to here is a volume average diameter, and is measured using a Coulter counter (manufactured by Coulter). Thereafter, it was cured by ultraviolet irradiation (step ST4 in FIG. 3), and a coating film layer 10 having irregularities with a thickness of 15 μm was formed on the base roughening surface 11a on which the polyester film was sandblasted. The glossiness of the surface 10a of the coating layer 10 (see FIG. 2) of the projection screen (see sample number 3 in Table 1) obtained by the above process was 23.4.

Each projection screen sample produced in this way was evaluated for projection performance by a projector and writing erasure performance using a whiteboard marker. These evaluation methods are described next.
(1) Antiglare property

An image was projected from a distance of about 2 m in front of the projection screen using a commercially available liquid crystal projector (PT-LB75, manufactured by Panasonic, maximum luminance: 2600 lumens), and the quality of the projected image was visually evaluated. Here, in the column of glossiness (antiglare property) in Table 1, “◎” was given to those in which a projected image was obtained to the extent that no hot spot was observed on the screen. The presence of a hot spot was recognized, but the effect was low to the extent that there was no hindrance to the visual observation of the projected image, and an acceptable clear projection image was marked as “◯”. In addition, the presence of hot spots was greatly recognized, and the effect was so great that it interfered with the visual recognition of the projected image (ie, complained of symptoms such as “eyes were tired”), and a clear projected image could not be obtained. Things were marked with x. Further, in Table 1, the glossiness variation σ is shown as a value obtained by measuring 9 points of glossiness and calculating the standard deviation thereof. The coefficient of variation was described as a percentage of the value obtained by dividing the glossiness variation σ by the glossiness.
(2) Marker writing erasability

Using black commercial whiteboard markers (Panasonic blackboard markers (product name: Erasa Panasonic)) This writing and erasing was repeated 50 sets. The marker ink wiping property was evaluated by measuring the color difference ΔE, that is, the amount of change in the L ^* a ^* b ^* value before and after the writing / erasing test described above. . In the background column of Table 1, those with ΔE of 2 or less are marked with ◯, and those with no ΔE are marked with ×.

  As a result of the above evaluation, as shown in Table 1, both the antiglare property and the marker writing erasability had sufficient performance. In particular, the antiglare property has excellent performance.

When the scratch hardness (pencil method) of the projection screen sample of sample number 3 was measured by the method described in JIS K 5600-5-4, all the samples had a pencil hardness of B or higher. . That is, it has sufficient performance with respect to wear resistance.
[Example 2 (sample number 1), Example 3 (sample number 2)]

  Using the same manufacturing method as in Example 1 above, projection screen samples of Sample No. 2 and Sample No. 3 shown in Table 1 were produced. However, the difference in configuration from the sample of Example 1 is in the base glossiness of the polyester film surface obtained by the base roughening treatment on the surface of the polyester film used as the substrate 7 (see FIG. 2). As shown in Table 1, the base glossiness is 1 and 2, respectively.

  These polyester films subjected to the surface roughening treatment are those obtained by subjecting Mitsubishi Plastics: Diafoil W-200 to sandblast treatment, as in Example 1. In order to obtain different base glossiness using the same sandblasting treatment, as described above, the particle size, number, shape, and application speed of the sand applied to the surface of the base material 7 to which the surface roughening treatment is applied are adjusted. This is possible. The photograph after the sandblasting treatment of the polyester film surface by step ST1-2 in FIG. 3 is shown in FIG. As shown in Table 1, the gloss of the coating layer 10 (see FIG. 2) surface 10a of sample number 1 (see table 1) obtained by the above steps is 20.2, and the coating layer 10 of sample number 2 The glossiness of the surface 10a was 21.5.

  The projection screen samples (sample numbers 1 and 2) produced in this way were evaluated for anti-glare by a projector and writing erasure using a whiteboard marker by the same evaluation method as in Example 1 above. did. As a result, as shown in Table 1, it had sufficient performance for both antiglare property and marker writing erasability. In particular, the antiglare property has excellent performance.

In addition, about the screen sample for a projection of this sample number 2, when scratch hardness (pencil method) was measured by the method of JISK5600-5-4, all the samples had pencil hardness B or more. . That is, it has sufficient performance with respect to wear resistance.
[Example 4 (sample number 4) to Example 10 (sample number 10)]

  Using the same manufacturing method as in Example 1 above, projection screen samples with sample numbers 4 to 10 shown in Table 1 were produced. Among the polyester films subjected to the surface roughening treatment, the projection screen samples of sample numbers 4 to 7 were subjected to sand blasting treatment for Mitsubishi foil: Diafoil W-200, as in Example 1. Is. As described above, by adjusting the particle size, number, shape, application speed, etc. of sand applied to the surface of the base material 7 to be subjected to the surface roughening treatment, the background glossiness can be changed. In addition, the projection screen samples of the remaining sample numbers 8 to 10 are mat-coated on the same Mitsubishi resin: Diafoil W-200. These different base glossinesses can be realized by changing the particle size or content of titanium oxide, calcium carbonate or the like.

  Among these samples, the base glossiness of sample number 5 was 10. Moreover, it was in the range of 6-65 also about the foundation | substrate glossiness of the other sample numbers 4 and 6-10. Specifically, it is as shown in Table 1. FIG. 7A shows a photograph of the projection screen sample of sample number 5 after sandblasting the polyester film surface in step ST1-2 of FIG. Moreover, about the projection screen sample of the sample number 9, the photograph after the sandblasting process of the polyester film surface by process ST1-2 of FIG. 3 is shown in FIG.7 (b).

  The glossiness of the surface 10a of the coating layer 10 (see FIG. 2) of Sample No. 5 (see Table 1) obtained by the above process was 24.3. Moreover, about the glossiness of the surface 10a of the coating-film layer 10 (refer FIG. 2) of the other sample numbers 4 and 6-10, it is as showing in Table 1, and all were in the range of 24-37.

  The projection screen samples thus prepared (sample numbers 4 to 10) were evaluated for anti-glare by a projector and writing erasure using a whiteboard marker by the same evaluation method as in Example 1 above. did. As a result, all of the screen samples had sufficient performance for both antiglare property and marker writing erasability. In particular, the antiglare properties of sample numbers 4 to 7 have extremely excellent performance.

In addition, when the scratch hardness (pencil method) of each of the projection screen samples of sample numbers 4 to 10 was measured by the method described in JIS K 5600-5-4, each sample had a pencil hardness of B or higher. Was. That is, it has sufficient performance with respect to wear resistance.
[Comparative Example 1 (Sample No. 11), Comparative Example 2 (Sample No. 12)]

  Using the same manufacturing method as in Example 1 above, projection screen samples with sample numbers 11 and 12 shown in Table 1 were produced. The polyester film that has been subjected to the surface roughening treatment is the same as the screen sample for projection of sample numbers 8 to 10 in Example 3, but is made by applying a mat coating to Diafoil W-200 made by Mitsubishi Plastics. . Their base glossiness is 75 and 90, respectively, as shown in Table 1.

  The glossiness of the surface 10a of the coating layer 10 (see FIG. 2) of the sample numbers 11 and 12 (see Table 1) obtained by the above steps was 40.2 and 45.2, respectively. As a result of evaluating the antiglare property by the projector and the writing erasure property using the whiteboard marker by the same evaluation method as in Example 1, the marker writing erasability has sufficient performance, but the antiglare property Has not obtained sufficient performance. Thereby, it turned out that the base roughening process to the coating surface of the base material 7 (refer FIG. 2) contributes to the improvement of anti-glare property.

  The base roughening treatment described above is preferably performed on the base material 7 so that the base glossiness is as low as possible. The projection screen sample of sample number 1 having the lowest base glossiness 1 in Table 1 has a lower gloss value (20.2) than that of the other sample numbers. )have. That is, the lower the base glossiness, the lower the glossiness of the surface 10a of the coating layer 10 as a whole. As a result, the diffuse reflectance of light is further improved. However, the background roughening treatment does not provide an endlessly low background gloss for the substrate 7. Under the present circumstances, the base glossiness that can be easily realized on the low value side is usually 3 to 2, and can be up to 1.

  The marker writing erasability is affected by the surface roughness of the coating layer 10 (see FIG. 2), that is, the arithmetic average roughness Ra and the average peak spacing Sm, depending on the state of the coated surface of the substrate 7. The If the base glossiness of the substrate 7 is lowered too much, this time, the unevenness of the coated surface subjected to the base roughening treatment, that is, the base roughening surface layer 11 (see FIG. 2) becomes large. As a result, the marker ink remaining in the recessed portion of the coating film layer 10 is difficult to wipe off, which becomes a factor of reducing erasability.

  More specifically, it is as follows. Spherical fine particles 8 (see FIG. 2) included in the coating layer 10 applied on the base surface-roughening surface layer 11 are affected by the unevenness of the base surface-roughening surface layer 11 so as to vary greatly in the vertical direction. The irregularities of the matrix resin 9 (see FIG. 2) that covers the spherical fine particles 8 and the substrate 7 are formed following the arrangement of the spherical fine particles 8. That is, the portion where the spherical fine particles are arranged protrudes from the portion where the spherical fine particles are not arranged. Therefore, when the spherical fine particles 8 are arranged on the surface roughening surface layer 11 of the base material 7 so as to vary greatly due to the unevenness, the unevenness of the matrix resin 9 that covers and follows the unevenness becomes large. As a result, it becomes difficult to wipe off the marker ink remaining in the recessed portion of the coating film layer 10 and the erasability is lowered. It is also conceivable that the protruding portion of the surface roughening surface layer 11 is exposed from the surface 10 a of the coating layer 10. In addition, it is also conceivable that the substrate roughening treatment itself may cause the base material 7 itself to lose its rigidity or be unable to withstand the holding of the coating film layer 10. In order to avoid such a phenomenon, it is desirable to set the base glossiness of the coated surface of the base material 7 to 1 or more, and this is the current limit in manufacturing.

  As described above, according to Examples 1 to 10 and Comparative Examples 1 and 2, the coating surface of the base material 7, that is, the surface in contact with the coating film layer 10 is subjected to the ground surface roughening treatment to form the ground surface roughening surface layer 11. By setting the glossiness to 1 to 65, the diffuse reflectivity of light is further improved. Therefore, even in a high-brightness projector apparatus, a phenomenon in which the light source of the projector appears as a bright spot at the center of the projected image, so-called hot It is possible to provide a projection screen capable of obtaining a clear projection image that does not generate a spot and capable of writing or erasing a marker on the projection plane, and a whiteboard device using the projection screen. In particular, if the base gloss of the substrate 7 is 1 to 30, high antiglare performance can be obtained.

Further, as is clear from the two evaluation items of “Glossiness variation σ” and “Variation coefficient” in Table 1, when the base glossiness is higher than 30, the antiglare property is only inferior compared with 30 or less. In addition, the “variation σ” and “variation coefficient” of the surface glossiness also increase. If the base glossiness is suppressed to 30 or less, not only the surface glossiness itself can be kept low, but also the “variation σ” of the surface glossiness and the “variation coefficient” that is a comparison index thereof can be reduced. it can. This means that if the base gloss is lowered (the base roughening surface 11a is appropriately roughened), the uneven shape of the surface 10a of the coating layer 10 formed thereon can be stably formed. .
(Relationship between surface irregularity and surface glossiness / marker writing erasability)
[Example 11 (Sample No. 14) to Example 17 (Sample No. 20)]

  Table 2 shows the glossiness of the coating layer 10 surface 10a, which is an evaluation index of antiglare properties, and the evaluation index of marker writing erasability for each projection screen sample having different surface irregularities of the coating layer 10. This shows the degree of soiling on the surface 10a of the coating layer 10. Table 2 shows the glossiness of the surface 10a of the coating layer 10 and the degree of background contamination for the projection screen samples of sample numbers 13 to 21. Here, the glossiness of the surface 10 a of the coating layer 10, that is, the evaluation method of antiglare property, is the same as that described in “(1) Antiglare property” of Example 1 above. The marker writing erasability evaluation method is also the same as that described in “(2) Marker writing erasability” of Example 1 above.

  These projection screen samples Nos. 13 to 21 were produced by the same process as in Example 1 above. However, the glossiness of the surface of a white polyester film (Mitsubishi Resin: Diafoil W-200, glossiness 99) having a thickness of 125 μm as the substrate 7 (see FIG. 2) of these projection screen samples is Both were set to 10.

  Of these projection screen samples from Sample Nos. 13 to 21, Sample Nos. 14 to 20 were found to have sufficient performance in both antiglare properties and marker writing erasability. That is, the glossiness of the surface 10a of these coating film layers 10 was 40 or less, and ΔE was 2 or less for the background stains. In particular, for sample numbers 14 to 18, the glossiness of the surface 10a of the coating film layer 10 was 30 or less, and it had extremely excellent antiglare performance.

  In such projection screen samples with sample numbers 14 to 20 having sufficient performance for antiglare property and marker writing erasability, the uneven shape of the surface 10a of each coating layer 10 was examined. As described above with reference to FIG. 2, each measurement parameter related to the uneven shape of the surface 10 a of the coating layer 10 is defined in JIS B 0601: 2001. As a result of measuring the surface 10a of the coating layer 10, the arithmetic average roughness Ra is in the range of 0.3 ≦ Ra ≦ 4, and the average peak interval Sm is divided by the arithmetic average roughness Ra. It was found that / Ra should be in the range of approximately 30 ≦ Sm / Ra ≦ 150. Further, the arithmetic average roughness Ra is in the range of 0.9 ≦ Ra ≦ 4, and the value Sm / Ra obtained by dividing the average peak interval Sm by the arithmetic average roughness Ra is approximately 30 ≦ Sm / Ra. If it is in the range of ≦ 130, extremely excellent antiglare performance can be exhibited while having sufficient performance for marker writing erasability (sample numbers 14 to 19).

  As a result of evaluating another projection screen sample not listed in Table 2, when the arithmetic average roughness Ra becomes 0.3 or less, the glossiness of the surface 10a of the coating layer 10 rapidly increases, and the gloss It was difficult to make the degree 40 or less. Further, when the arithmetic average roughness Ra is 4 or more, the wear of the marker whose tip is made of felt is accelerated. Moreover, since the unevenness | corrugation of the surface 10a of the coating film layer 10 becomes large, erasure | elimination of the marker ink written on the surface 10a of the coating film layer 10 becomes difficult. This point will be described in Comparative Examples 3 and 4 to be described later.

The most desirable value of Sm / Ra was about 70 to 80 (sample number 17). The value of Sm / Ra increases to about 100 as writing and erasing are repeated on the surface 10a of the coating layer 10 even if the initial value is about 70. Therefore, if the initial value of Sm / Ra becomes larger than this, it will show a higher value after repeated writing and erasing. When Sm / Ra is 150 or more, the light diffusion reflectivity becomes too small, and a hot spot is generated, so that projectability is deteriorated. On the other hand, when Sm / Ra is 30 or less, the erasability of the marker ink decreases. This point will also be described in Comparative Examples 3 and 4 to be described later.
[Comparative Example 3 (Sample No. 13)]

  Of the projection screen samples from Sample Nos. 13 to 21 shown in Table 2, Sample No. 13 is satisfactory in terms of anti-glare properties, but has insufficient performance for marker writing erasure. That is, the glossiness of the surface 10a of the coating layer 10 was 40 or less, but the background stain was ΔE of 2.2, which exceeded 2.

Further, the arithmetic average roughness Ra is 4.3 and exceeds 4. For this reason, the wear of the marker whose pen nib is made of felt was accelerated. Moreover, since the unevenness | corrugation of the surface 10a of the coating film layer 10 became large, erasure | elimination of the marker ink written on the surface 10a of the coating film layer 10 became difficult. This is apparent from the fact that ΔE, which is the evaluation index of soil contamination described above, exceeded 2.
[Comparative Example 4 (Sample No. 21)]

  Of the projection screen samples from Sample Nos. 13 to 21 shown in Table 2, Sample No. 21 is satisfactory in terms of marker writing erasability, but sufficient performance is not obtained in terms of anti-glare properties. That is, ΔE was much less than 2 for the soil on the surface 10 a of the coating layer 10, but the glossiness was 41.1 and exceeded 40.

As described above, according to Examples 11 to 17 and Comparative Examples 3 to 4, the surface roughening surface layer 11 is previously formed on the coating surface of the base material 7, and then the surface unevenness shape of the coating layer 10 to be formed thereon is defined. Among the values, the arithmetic average roughness Ra specified in JIS B 0601: 2001 is in the range of 0.3 ≦ Ra ≦ 4, and the average mountain interval Sm specified in JIS B 0601: 2001 is the arithmetic average roughness. It was found that by having the value Sm / Ra divided by Ra in a range of approximately 30 ≦ Sm / Ra ≦ 150, the marker ink was wiped and diffused and reflected. For this reason, even in a high-brightness projector device, it is possible to obtain a sharp projected image in which the light source of the projector looks like a bright spot in the center of the projected image, that is, a so-called hot spot, A projection screen capable of writing and erasing and a whiteboard device using the same can be provided. In particular, if the base gloss of the substrate 7 is 1 to 30, high antiglare performance can be obtained.
(Base surface roughening treatment)

  On the other hand, in order to set the glossiness of the surface 10a serving as the screen surface to 40 or less, it is assumed from Table 1 that the base glossiness is 65 or less. Based on this precondition, the base surface roughening treatment of the base material 7 without the mat coating treatment will be described below.

  First, a base material made of white PET having a base gloss level (55) equivalent to that of sample number 9 in Table 1 and not subjected to base roughening treatment by sandblasting was examined. The white PET base material had a base glossiness of 55.4, and the titanium oxide contained in the base material was added at an average particle size of 0.25 μm and a content (wt%) of 8 wt%. A photograph of this surface is shown in FIG.

  FIG. 9 is an essential part enlarged cross-sectional view schematically showing a state in which fine particles of titanium oxide are contained in a white PET base material. As shown in the figure, the ground surface 7a is uneven due to the fine particles 31 scattered in the vicinity of the surface (base surface) 7a of the white PET base material 7. The rough surface of the ground surface 7a formed in this way forms a ground surface roughening surface that has been subjected to the ground surface roughening treatment similar to the above-described mat coating and ground surface roughening treatment.

  Next, the change of the glossiness (base glossiness) of the base surface 7a when the average particle diameter and content of titanium oxide contained in the white PET base material were changed was measured. The results are shown in Table 3 and graphed FIG. In addition, when the average particle diameter is 0.6 μm or more, or when the titanium oxide containing the content of the base material 7 exceeds 20 wt%, pinholes are easily generated when the white PET base material is stretched. The upper limit.

  As shown in Table 3, when the average particle size is 0.05 μm, the base glossiness exceeds 65 regardless of the content rate. As a result, when the average particle diameter of titanium oxide is in the range of 0.1 to 0.5 μm and the content is 3 to 20 wt% (thick line frame), the glossiness (antiglare property) of the surface (projection surface) is 40. It has been found that the base gloss, which is a precondition for the following, can satisfy 65 or less.

  FIG. 11 is a flowchart showing a manufacturing process in sand blasting of a white PET substrate. First, in step ST1, for example, a film (white PET) as a material of the base material 7 wound around a roll is sent out. In step ST2, sandblasting is performed on the surface that is the projection surface of the film fed from the roll. In step ST3, washing with water is performed, draining is performed in step ST4, drying in warm air (80 ° C.) is performed in step ST5, and the film is wound on another roll in step ST6.

  Table 4 and graphed FIG. 12 show the results of measuring the change in the base gloss after the sand blasting process in the step of FIG. 11 for each white PET substrate in Table 3 above. As shown in Table 4, by the sandblast treatment, the base glossiness of each white PET base material was further lowered as compared to the untreated sandblast state.

  In particular, for the white PET substrate having an average particle size of 0.1 to 0.5 μm and a content of 3 to 20 wt%, the base gloss was 20 or less. In Table 1 described above, the glossiness (marked with ◎) (that is, a projected image that is clear enough to prevent the presence of hot spots on the screen) is 30 or less. All of the thick-lined frames in Table 3 were found to have an extremely good gloss level (antiglare property), with the gloss level being significantly below 30.

  In Table 4, although the white PET base material containing titanium oxide was described, this is the same when another resin material containing titanium oxide is used as the base material. Examples of base materials using other resin materials will be described with reference to Table 5.

  In Table 5, white PET is the base material shown in Tables 3 and 4 above, a product obtained by adding titanium oxide to PET (polyethylene terephthalate), and white PEN added titanium oxide to PEN (polyethylene naphthalate). The white PP is a product obtained by adding titanium oxide to PP (polypropylene), and the white PE is a product obtained by adding titanium oxide to PE (polyethylene).

  As described in Table 5, in the case of white PEN, the heat resistance is high, and there is a feature that the shrinkage at the time of hot air drying in step ST5 is small, the heat resistance is higher than PET (about 50 ° C.), There is an effect that deformation of the film is small during UV irradiation. In addition, white PP has a feature that the processability of the sandblasting process is good, and has an effect that an uneven surface that scatters light more easily than PET. Further, white PE has a feature that sandblasting processability is good like white PP, and has an effect that it is easy to create an uneven surface that scatters light than PET. Thus, the material of the base material 7 is not limited to white PET, and may be white PEN, white PP, white PE, or the like. By selecting the base material 7 in consideration of the above characteristics, the characteristics of the screen when it becomes a product can be obtained.

  As described above with reference to Tables 3 and 4 and FIGS. 10 and 12, the average particle diameter of titanium oxide contained in the base material 7 is in the range of 0.1 to 0.5 μm, and the content is 3 to 20 wt%. By being in each of the ranges, it is possible to secure a background gloss level that can suppress the occurrence of so-called hot spots by the high-intensity projector, and the diffuse reflection property of the projection light is maintained. Further, by performing the sandblast treatment, it is possible to achieve the glossiness of the projection surface capable of ensuring good anti-glare properties, and to obtain extremely excellent performance.

  Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to such embodiments so that those skilled in the art can easily understand, and departs from the spirit of the present invention. For example, the present invention can be applied to an electronic blackboard device. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

  According to the projection screen of the present invention, a clear projected image can be obtained even in a projector device with high brightness, and is also useful as a projection screen for whiteboard.

DESCRIPTION OF SYMBOLS 1 White board apparatus main body 2 Board surface 3 Personal computer 4 Projector apparatus 5 Marker 6 Eraser 7 Base material 7a Ground surface 8 Spherical fine particle 9 Matrix resin 10 Coating layer

Claims (5)

A substrate;
A projection screen comprising: a coating layer formed on the surface of the substrate, and an exposed surface opposite to the surface in contact with the substrate;
The base material has a plurality of particles of titanium oxide having an average particle diameter of 0.1 to 0.5 μm and a content rate of 3 to 20 wt%,
A projection screen, wherein a base roughening surface having irregularities is formed by a plurality of particles of the titanium oxide on a contact surface of the substrate with the coating layer.   The projection screen according to claim 1, wherein the unevenness of the base roughening surface is defined by a 60 ° specular gloss, and the range thereof is 1 to 65.   The projection screen according to claim 1, wherein the surface roughening surface further has a concavo-convex shape obtained by sandblasting.   4. The projection screen according to claim 1, wherein the 60 ° specular glossiness of the exposed surface is 40 or less.   5. A whiteboard device, wherein a board surface on which writing is erased is formed by the projection screen according to any one of claims 1 to 4.