MXPA99011358A

MXPA99011358A - Self light-emitting retroreflective sheet and method for producing the same

Info

Publication number: MXPA99011358A
Application number: MXPA/A/1999/011358A
Authority: MX
Inventors: Araki Yoshinori; Abe Hidetoshi; Matsumoto Kazumi
Original assignee: Minnesota Mining & Mfg Co <3M>
Priority date: 1997-06-16
Filing date: 1999-12-07
Publication date: 2000-06-01

Abstract

The present invention provides a self light-emitting retroreflective sheet including a light-transmitting retroreflective element including a plurality of prismatic projections, a lining film, and an electroluminescence device. The lining film includes a light-transmitting film which has sealing projections on one of its surfaces so that the prismatic projections are confined within a plurality of sealed cells formed by the sealing projections. In the sealed cells, a surface of the prismatic projections interface with air so as to increase light-emitting luminance and improve its uniformity.

Description

HCJA R? TRORREF? CTIV QU? EMIT OWN LIGHT ^ > _- PRODUCE THE SAME Field of the Invention The present invention relates to a retroreflective ho that emits its own light and a method to produce it. In particular, the present invention relates to a reorreflective sheet comprising an electroluminescent device (EL device) and a prismatic retroreflective element, and a method for producing the same.

Background of the Invention Prismatic retroreflective sheets such as the cube corner prismatic retroreflective sheets are used as display plates such as traffic signs or outdoor advertising signs, since they have a very high reflective luminance and improve visibility by the night more effectively than glass beads of the retroreflective sheet type. _ Now, the structures and functions of the prismatic retroreflective sheets will be briefly explained.

REF .: 32126 The prismatic retroreflective sheet comprises a retroreflective element having a main surface on which a plurality of prismatic projections is placed, and a lining or lining film is made of a resin that transmits light, and the retroreflective element and the coating film are partly attached so that the tiny sealed cells are formed between them. The surfaces of the prismatic projections are confined with having interfaces with an air, and the prisms that have the interfaces with the retroreflection of air of the incident light in the high luminance. The sealing projections, which bind particularly to the retroreflective element and form the sealed cells, are normally formed by embossing the resin film, which is a precursor of the coating film, its opposite surface and the protuberances of the lateral surface. of the resin film. However, such rotrereflective sheets have to improve their limitation on visibility at night in places where limited light sources such as the front lamps of automobiles are useful, for example, on side roads that do not have nearby lights, since the leaves are only seen by passers-by when the leaves reflect the light that illuminates them. That is, the sheets do not work enough as the advertising or traffic signals which provide information at night to pedestrians in the above circumstances. Thus, to solve such problems, several proposals have been made, for example, in JP-A-8-502131 (See, US Patent Nos. 5,315,491 and ,300,783) and in W092 / 14173 (See, US Patents Nos. 5,243,457 and 5,237,448). These publications describe the retroreflective sheets that emit own light which comprise a cube corner prismatic retroreflective element, and an EL device or a phosphorescent layer, which has a relatively thin thickness. That is, the retroreflective sheets of the following types (a), (b) and (c) are described as follows: (a) A retroreflective sheet comprising 'corner prisms, and the EL devices having the caps transparent superiors which are in close contact with the prismatic projections on the extreme surfaces. (b) A retroreflective sheet comprising corner cube prisms which are confined in sealed cells under the condition that the surfaces of the prism projections have interfaces with an air, with the transparent adhesive layers which are filled into the cells in contact with the projections of the prism, and the EL devices adhered to the opposite surfaces of the adhesive layers in the cells. _ ^ (c) A retroreflective sheet comprising corner cube prisms, and EL devices provided in the cells that enclose the prism projections under the condition that the surfaces of the projections have interfaces with an a? re = at a certain distance of the projections of the prism. The retroreflective sheet (a) emits light effectively when the EL device is turned on, but does not retroreflect to the incident light since the surfaces of the projections of the prism do not have interfaces with the air. The retroreflective sheet (b) can emit light effectively in areas where the EL devices are in contact with the cube corner prisms through the "transparent adhesive layers, and there may be retroreflection of incident light in areas where no EL device is However, EL devices emit light on parts of the surface of the blade that have the corner prisms of the cube, but do not emit light evenly over the total surface of the blade I Retroreflective sheet (c) can retroreflect The light incident on the total surface of the sheet but the EL devices emit light on the parts of the surface of the sheet A retroreflective sheet in which a coating film that emits phosphorescence is provided on the opposite surface of a retroreflective prismatic element is known and described in, for example, U.S. Patent No. 5,415,911 and JP-A-7-218708, however, this sheet can not be emit light as brightly as EL devices do. X Summary The application of retroreflective sheets in the field of traffic and advertising signs is one of the important objectives to increase the luminance (luminance of own light emission) of retroreflective sheets, when bystanders do not have any source of light that observe, the leaves in the circumstances where retroreflection does not occur, ie the retroreflective sheets are not or poorly illuminated with the external light source. However, the above conventional retroreflective sheets can not increase the luminance of the EL devices themselves while maintaining sufficient retroreflectivity of the sheets. Thus, an object of the present invention is to provide a retroreflective sheet that emits own light which has sufficient retroreflectivity (reflection luminance), and increase the luminance of light emission so that its visibility is sufficient at night even when there is no no external light source and does not occur-retroreflection. To achieve the above objective, an aspect of the present invention provides a retroreflective sheet that emits own light 100 comprising: A) a retroreflective member 10 comprising (i) a retroreflective element that transmits light 1 having a substantially planar surface, and an opposite surface on which a plurality of prismatic projections is placed, and (ii) a coating film 2 comprising a film that transmits light, which has protuberances by embossing and has, on its surface, the projections of sealed 21 which are in part attached to the opposite surface of the retroreflective element 1 so that the prismatic projections are confined while the surfaces of the prismatic projections have interfaces with an air and form a plurality of sealed cells 23, and B) an electroluminescent device 3 what has a surface that emits substantially flat light 31 that extend substantially e in the total area of the opposite surface of the coating film 2, wherein the sheet additionally comprises a contact layer that transmits light 4 which is filled with depressions 22 formed by embossing on the opposite surface of the coating film 2 and substantially attaches to the total surface area of the opposing surface of the coating film, and also substantially to the total area of the light emitting surface 31 of the electroluminescent element 3. Preferably, the retroreflective element that transmits light 1 has a light transmission of at least 70%, the coating film 2 has a light transmission of at least 20%, and the contact layer 4 has a light transmission of at least 30%.

The retroreflective sheet that emits light of the present invention may additionally include a protective film 5 on the substantially planar surface of the retroreflective element that transmits light 1. Preferably, the sealing projections 21 which are in part attached to the opposite surface of the retroreflective element 1, form an adhesion area of about 10% to about 85% of the total opposite surface of retroreflective element 100. Another aspect of the present invention is to provide a method for producing a leaf that emits own light as described above. Preferably, the method includes the steps of placing a resin film which is a precursor of the coating film 2 with its surface opposite the opposite surface of the retroreflective element 1 by leaving a specific distance from the "opposite surface of the retroreflective element 1. , embossing the resin film of its opposite surface to make protrusions partly on its surface and forming the sealing projections 21 which are attached to the opposite surface of the retroreflective element 1, where the retroreflective member 10 having a plurality of spaces is formed. sealed 23, forming a coated layer having a substantially flat liquid surface by applying a polymerizable liquid on the opposite surface of the coating film 2 and filling the depressions 22 formed by embossing and polymerizing the liquid coating and forming a contact layer 4 having the substantially flat surface which is formed from the substantially flat liquid surface and is bonded to the coating film 2, and placing an electroluminescent element 3 on the substantially flat surface of the contact layer 4 so that its surface 31 which emits light is in contact with the contact layer 4.

Brief Description of the Drawings Figure 1 is a cross-sectional view of an example of the retroreflective sheet according to the present invention, Figure 2 is a cross sectional view of an example of the rolled EL device which is used in the retroreflective sheet according to the present invention.

Detailed Description In the retroreflective sheet 100 of the present invention, the contact layer 4 joins the EL 3 device and the coating film 2 on all its surfaces so that no gaps are formed by the depressions 22 corresponding to the embossed marks that t remain between the surface emitting substantially planar light 31 of the device EL 3 and the opposite surface of the coating film 2. If such recesses remain, the ethereal interfaces are formed between the device EL 3 and the coating film 2. and reflect the light of the EL device. Thus, the amount of light that the coating film 2 reaches, that is, decreases to the retroreflective member 1. The retroreflective sheet of the present invention can decrease the amount of light reached from the EL 3 device to the retroreflective member 10"due to reflection in the ethereal interfaces, and the light emission luminance can be increased. When the transparent conductive layer is directly attached to the opposite surface of the coating film 2, and thus the transparent conductive layer having corresponding teeth is formed. to the depressions 22, the light emitting layer which is formed with the close contact to the transparent conductive layer tends to have an irregular thickness, and the thickness of the light emitting layer decreases the luminescent efficiency. effectively avoids the decrease in luminescent efficiency and also decreases the luminance of light emission.The retroreflective element pr ismatic 1 (sometimes called "retroreflective element") retroreflects incident light with a high luminance into a plurality of tiny sealed cells that are formed to confine the prismatic projections under the condition that the surfaces of the projections have interfaces with an air. The retroreflective member allows transmission of the light emitted from the EL devices through the complete retroreflective element 1 (ie, the areas to which the sealing projections 21 are attached and the areas that have the cells sealed), and the surface complete of the sheet that emits light, since the sealing projections have light transmission properties. The contact layer, the coating film and the retroreflective element are made of light transmission materials. The light transmission of the laminate of these three members is normally at least 30%, preferably at least 40%, more preferably less than 45%. The uniformity of the luminance can be improved when at least one of the contact layer, the coating film and the retroreflective element contains diffusely reflecting particles and the "light transmission of the laminate is preferably between 30 and 70%, more preferably between 40 and 65% When it is desired to improve the effect to increase the luminance of the light emitted from the EL device instead of the uniformity of the luminance of diffused light, the light transmission of the laminate is preferably at least 70 %, in particular at least 80% .The light transmission of the laminate is the transmission of light which propagates from the lateral contact layer to the retroreflective element.In the present, the "transmission of light" means that a light transmission measured with 550 nm light using a visible light / UV light spectrophotometer "U Best V-560" - manufactured by Nippon Bun or Kabushikikaisha. of the above three members is selected so that the laminate of the three members has light transmission in the above interval. In general, the retroreflective element is made of a material having a light transmission of at least 70%, the coating film is made of a material having a light transmission of at least 20%, and the contact layer is makes a material that has a light transmission of at least 30%. Thus, the laminate of the three members has a light transmission of at least 30%. _ The light transmission of the retroreflective element is the transmission of light that propagates from the surface opposite the surface. Almost the entire surface of the retroreflective element can be substantially flat, since the sealing projections to form the sealed cells are joined to the opposite surface of the retroreflective element. When almost the entire surface of the retroreflective element is substantially flat, the displays can be easily provided on the surface by conventional etching methods. That is, the retroreflective sheet of the present invention is preferably used as a member of a retroreflective signal. The retroreflective sheet of the present invention can be produced by several methods.

Preferably, it is produced by the method comprising the steps of: I) placing a resin film which is a precursor of the coating film 2 with its surface opposite the opposite surface of the retroreflective element 1 by leaving a specific distance from the opposing surface of the retroreflective element 1, II) embossing the resin film of its opposite surface to make protrusions on part of its surface and forming the sealing projections 21 which join the opposite surface of the retroreflective element 1, thus form the retroreflective member 10 having a plurality of sealed spaces 23, III) form a cover layer having a substantially flat liquid surface by applying polymerizable liquid on the opposite surface of the coating film 2 and filling the depressions 22 formed by the embossing, IV) polymerize the coating liquid and form a layer of contact 4 having the substantially flat surface which is formed of the liquid surface substantially flat and is bonded to the coating film 2, and V) placing an electroluminescent element 3 on the substantially flat surface of the contact layer 4 so that its surface that emits light 31 is in contact with the contact layer 4. This method can preferably fill the depressions 22 and quickly form the structure in which the coating film 2 and the EL device are bonded to the contact layer 4. Preferred embodiment of the retroreflective sheet of the present invention will be explained with reference to Figure 1. The retroreflective sheet 100 comprises a prismatic retroreflective member 10, an EL 3 device, and a contact layer 4 interposed therebetween. The prismatic retroreflective member 10 comprises (i) a retroreflective light transmission element 1 having a substantially planar surface and an opposing surface on which a plurality of prismatic projections is placed, and (ii) a coating film 2 made from a resin that transmits light. The element 1 and the coating film 2 are in part joined so as to form a plurality of sealed small cells 23.

The surfaces of the prismatic projections 24 are confined as long as they have interfaces with an air. The sealing projection 21 is formed by protruding on the surface of the resin film which is a precursor of the coating film 2 by embossing the film on its opposite surface, and being partly attached to the retroreflective element 1. Thus , the opposite surface of the coating film. 2 has depressions corresponding to the marks formed by the embossment. The device EL 3 is provided so that the light emitting surface 31 extends substantially over the entire opposite surface of the revelation film 2. The details of the EL device will be explained later. The contact layer 4 substantially joins the entire opposite surface of the coating film 2 while the depressions 22 are filled, and also the flat surface 41 of the contact layer 4 substantially joins the entire surface emitting light 31 of the EL 3 device. The retroreflective element 10 may optionally have a protective film 5 which is laminated on the surface of the retroreflective element 1. In addition, an adhesive layer 6 may be provided on the opposite surface of the EL 3 device, ie the surface opposite to the The surface 31 is made of light, in order to facilitate the adhesion of the retroreflective sheet 100 to a substrate such as an aluminum signal plate.The retroreflective sheet of the present invention can be produced by forming the contact layer in the opposite surface of the retroreflective member which has been formed (after embossing), forming the transparent conductive layer, in the contact layer, and providing the EL device in the contact layer by laminating the elements of the EL device such as the luminescent layer and as in the transparent conductive layer. In this case, the surface of the transparent conductive layer (the surface attached to the contact layer) forms the surface that emits light. Alternatively, the opposite surface of the coating film of the finished retroreflective member and the light emitting surface of the finished EL device adhere through the contact layer.

Retruereflective Prismatic Element _ The prismatic retroreflective element is made of a resin having the light transmission of normally at least 70%, preferably at least 80%, in particular at least 90%. This type of prismatic retroreflective element can perform the high reflection luminance without the use of any metal reflection film which decreases the transparency of the retroreflective element, and can increase the luminance evenly over the total surface by the synergistic effect of the EL device emission and retroreflection. This type of prismatic retroreflective sheet can be produced by the methods described in JP-A-60-100103, in JP-A-6-50111, in the US Patent no. 4,775,219 and the like. For example, a molded plastic material that uses a mold that has a specific shape and arrangement. A preferred form of prismatic projection is a trigonal pyramid which is called as a cube corner. The cube corner can increase the reflection luminance and the wide viewing angle of the retroreflective element. The preferred sizes of a trigonal pyramid are between 0.1 and 3.0 mm on one side of the bottom triangle and between 25 and 500 μm in height. The background triangle can be an equilateral or isosceles triangle.

The resin, which forms the retroreflective element is preferably a very transparent one having a refractive index of between 1.4 and 1.7. Examples of such a resin are acrylic resins, epoxy-modified acrylic resins, polycarbonate resins, and the like. This resin may contain additives such as UV light absorbers, moisture absorbers, colorants (including fluorescent dyes), phosphors, heat stabilizers, fillers, and the like, unless the effects of the present invention are impaired.

Coating Film The coating film is made of a resin having the light transmission of at least 20%, preferably at least 30%. The light transmission of the coating film is between 20 and 80%, preferably between 25 and 75%, while the functions of the coating film are like the light diffusing member. The light transmission of the coating film is preferably at least 80%, more preferably at least 90%, when the luminance caused by the emission of the EL device is improved, it is sought instead of the uniformity of the luminance due to diffuse light. Examples of the resin film are those of polyester resins, acrylic resins, polyurethane, vinyl chloride resins, polycarbonate, polyamide, polyvinyl fluoride, polyvinylidene fluoride,. polybutyrate, and the like. This "resin film may contain additives such as" UV light absorbers, moisture absorbers, colorants (including fluorescent dyes), phosphors, heat stabilizers, diffuse reflection particles, and the like, unless the effects of the present invention are added. . Examples of the diffuse reflection particles are white inorganic particles such as titanium dioxide; polymer particles such as polystyrene particles; and similar. The thickness of the coating film is usually in the range of 10 to 1000 μm. The softening point of the film is preferably in the range of 80 to 250 ° C. The resin film can be produced by, for example, extrusion. The resin film can be a multi-capable film having two or more layers, unless the effects of the present invention are damaged.

Production of the Retroreflective Member The retroreflective member is produced by placing "the resin film which is the precursor of the coating film with its surface opposite the opposite surface of the retroreflective element by leaving a specific distance from the opposite surface of the retroreflective element., and embossing the coating film from its opposite surface. The embossment protrudes part of the surface of the resin film and forms the "sealing projections" which are attached to the opposite surface of the retroreflective element, thus forming a plurality of sealed cells.The temperature for embossing is normally above the softening point of the coating film, preferably between 100 and 300 ° C. The area of a tiny cell (the area of a part surrounded by the sealing projections) is preferably between 2.5 and 40 mm2, in articulation, between 5 and 30 mm2 When the area of a tiny cell is less than 2.5 mm2, the luminance of reflection is insufficient When the area of a tiny cell exceeds 40 mm2, the prismatic projections tend to break, the sheet wrinkles , or the appearance of the leaf is damaged by the wind or an impact.

The area of total adhesion of the sealing projections seen from the surface of the retroreflective element is between 10 and 85%, preferably between 20 and 70%, in particular between 30 and 60% of the total opposite surface of the retroreflective element. When the total adhesion area exceeds 85%, the retroreflective luminance tends to decrease. When the total adhesion area is less than 10%, the adhesive strength decreases and the coating film tends to detach from the retroreflective element. The area of total adhesion is increased to decrease the anterior area of a cell. The total adhesion area of the sealing projections can be increased up to 70% to achieve the luminance improvement due to the light emitted from the EL device when the coating film is the translucent film having the diffusion properties. The protective film 5 laminated on the surface of the retroreflective element 1 is preferably a transparent plastic film containing a UV light absorber to further improve the weather resistance of the retroreflective sheet. The transparent film can be made of plastics such as acrylic polymers, polymer blends of the acrylic polymer and polyvinylidene fluoride, and the like. The retroreflective member may be formed by the methods described in JP-A-60-100103, JP-A-6-50111, US-A-4775219, and the like.

EL Device The EL device has the laminated structure of the transparent conductive layer, the back electrode and the luminescent layer which is interposed between them. A light transmission film (non-conductive) can optionally be laminated to the surface of the transparent conductive layer. The surface that emits light may be the surface of the transparent conductive layer or the light transmission film. Such surface is flat. An insulating layer, if necessary, can be provided between the luminescent layer and the posterior electrode. These components are preferably bonded without "leaving an air layer between them." By increasing the luminance effectively on the total surface of the sheet, the luminance of own light emission is preferably at least 13 cd / m2 when only the light is turned on. EL device.

Transparent Conductive Layer ^ The transparent conductive layer can be formed by covering it directly on the substantially flat surface of the contact layer formed on the opposite surface of the coating film. The contact layer will be explained in detail later. The transparent conductive film can be any transparent electrode such as an ITO (Indian-tin oxide) film, and the like. The thickness of the transparent conductive film is usually between 0.01 and 1000 μm, and the surface resistivity is usually 500 O / squares or less, preferably about 1 and 300 O / squares. The light transmission is normally at least 70%, preferably at least 80%. The ITO film is formed by any conventional film forming method such as vapor deposition, electronic deposition, paste coating, and the like. The transparent conductive layer and the contact layer can be joined after the formation of the transparent conductive layer on the surface of the luminescent layer. Alternatively, the transparent conductive layer can be omitted, and the luminescent layer can be formed directly on the flat surface of the contact layer when the contact layer has sufficient conductivity. A laminated light transmission film and a transparent conductive film can be used as the transparent conductive layer. In this case, the transparent conductive layer is provided with the conductive film in front of the luminescent layer. Examples of the film that transmits light are plastic films such as polyethylene terephthalate. The transmission of light from the film is usually at least __ 70%, and the thickness of the film is usually between 10 and 1000 μm. The film that transmits light may contain a fluorescent dye that develops a color coupled to the color of the light emitted by the luminescent layer, and whereby the EL device emitting white light may be formed.

Posterior Electrode The posterior electrode 34 is placed on the opposite surface of the luminescent layer, i.e., the surface opposite the transparent conductive layer 30. The posterior electrode is normally in direct contact with the luminescent layer. When the insulating layer is present in contact with the opposite surface of the luminescent layer, the back electrode is provided to be in contact with the insulating layer. The back electrode can be a conductive film used in conventional dispersions of the type of EL devices, such as a metal film of aluminum, gold, silver, copper, nickel, chromium, etc .; a transparent conductive film such as an ITO film; a conductive carbon film; and similar. The metal film can be a vapor deposition film, an electron deposition film, a metal sheet, and the like. The thickness of the posterior electrode is usually between 5 nm and 1000 μm.

Luminescent layer The luminescent layer can be formed as follows: The matrix resin comprising the polymer with the high constant dielectric, with the fluorescent particles and a solvent, is mixed and dispersed homogeneously with a mixing apparatus such as a mixer ordinary, and a paint for the luminescent layer of the dispersion type is prepared. Then, it is covered and dried to form the luminescent layer. In this case, the paint can be applied directly to the transparent conductive layer, the back electrode or the insulating layer. Alternatively, the luminescent layer can be formed on a temporary support having release properties, and then transferred to the transparent conductive layer, the back electrode or the insulating layer. The solid content of the paint is usually between 10 and 60% by weight. The fluorescent particles are contained in an amount of between 50 and 200 parts by weight per 100 parts by weight of the matrix resin. The fluorescent particles may contain two or more types of particles. For example, at least two types of luminescent particles that emit blue, blue-green or orange light and that have a discrete spectrum one to the other are mixed, and a white luminescent layer can result. Alternatively, the luminescent layer comprises two or more sublayers containing particles that emit different colors. The coating medium, the coating thickness, the drying conditions, and the like are the same as those in the formation of the luminescent layer of the conventional dispersion type (see JP-B-59-14878, JP-B-62- 59879, etc.). The laminated luminescent layer 32 (ie, the laminated structure consisting of the support layer 38, the luminescent particle layer 37 and the insulating layer 36) can be formed as follows: First, a paint for forming the layer of Support is applied in the transparent conductive layer. Then, the luminescent particle layer is formed on the surface of the support layer by any powder coating method prior to drying the paint. After partially embedding the particles in the support layer, the support layer is dried. Therefore, the support layer and the particle layer are joined together. Finally, the insulating layer is laminated in the luminescent particle layer and the laminated structure having the joined layers is formed. The insulating layer can be formed by applying a paint containing materials to form the insulating layer and drying it The luminescent particle layer consists of a plurality of particles, which are placed in a single state of the layer and are bonded to both support and insulator layers The support layer and / or the insulating layer may be a sheet having two or more layers, unless the effects of the present invention are damaged.

Support layer for the Luminescent Layer The support layer is a transparent layer containing a matrix resin. The thickness of the support layer is usually between 5 and 1000 μm, and the light transmission is normally at least 70%, preferably at least 80%. The matrix resin may be a resin that is used in conventional EL-type dispersion devices such as epoxy resins, polymers having a high dielectric constant, and the like. The polymers having the high dielectric constant are those having a dielectric constant of normally at least about 5, preferably between 7 and 25, more preferably between 8 and 18, when it is measured by applying an alternating current of 1 kHz. When the dielectric constant is too low, the luminance can not be increased. When it is too high, the lifetime of the luminescent layer tends to be reduced. Examples of the polymers having the high dielectric constant are vinyiide fluoride resins, cyanoresins, and the like. For example, the vinylidene fluoride resin can be obtained by the copolymerization of vinylidene fluoride and at least one other fluorine-containing monomer Examples of the other fluorine-containing monomer are tetrafluoroethylene, trifluorochloroethylene, hexafluoropropylene, and the like. "Examples of cyanoresin are cyanoethyl cellulose, ethylene-vinyl cyanoethylated alcohol copolymer, and the like. X The support layer generally consists of the matrix resin, while it may contain additives such as other resins, fillers, surfactants, light absorbers -UV, antioxidants, antifungal agents, oxide preventatives, moisture absorbers, dyes, phosphors, and the like. , unless the effects of the present invention are damaged. And • For example, when the light emitted from the luminescent particle layer - is blue-green, the matrix resin contains red or pink fluorescent colors such as rhodamine 6G, rhodamine B, perylene colors, etc., or processed pigments formed by dispersing such dyes in a resin, and the white luminescent layer is formed.

Insulating layer for the Luminescent Layer The insulating material contained in the insulating layer for the luminescent layer can be insulating particles, the polymer has a high dielectric constant, and similar, "which are used in EL devices of the conventional dispersion type. Examples of the insulating particles are inorganic insulating particles of, for example, titanium dioxide, titanate barium, aluminum oxide, magnesium oxide, silicone oxide, silicon nitrid, and the like Polymers, which have high dielectric constant can be the polymers used for the support layer The insulating layer can be formed by coating the paint either the back electrode or the luminescent particle layer When the insulating layer is the coated layer comprising the insulating particles and the polymer which have the high dielectric constant, the amount of the insulating particles is between 1 and 400 parts weight, preferably between 10 and 300 parts by weight, more preferably between 20 and 200 parts by weight, per 100 parts by weight of the polymer having the high dielectric constant. When the amount of the insulating particles is too low, the insulating effect decreases, and thus the luminance tends to decrease. When the amount is too high, the application of the paint can be difficult. The thickness of the insulating layer is usually between 5 and 1000 μm. The insulating layer may contain additives such as fillers, surfactants, antioxidants, antifungal agents, oxide preventatives, moisture absorbers, colorants, phosphors, curable resins, adhesives, and the like, insofar as the insulating properties are "damaged.

Luminescent Particle Layer The luminescent particle layer can be fluorescent particles which are used in EL devices of the conventional dispersion type. "Examples of fluorescent materials are single substances of fluorescent compounds (eg, ZnS, CdZnS, ZnSSe, CdZnSe, etc.), or mixtures of the" fluorescent compounds and auxiliary components "(for example, Cu, I, Cl, Al, Mn, NdF3, Ag, B, etc.) The average particle size of fluorescent particles is usually between 5 and 100 μm The particulate fluorescent materials in which a film of glass lining, ceramic , and similar forms can be used.

The content of the luminescent particles in the luminescent particle layer is preferably at least 40% by weight, when the content is less than 40% by weight, the effects "to improve the luminance may decrease.The thickness of the luminescent particle layer is usually between 5 and 500 μm.When the fluorescent particle layer consists of a plurality of particles which are placed in a Only the state of the layer, the EL device can easily become thin; In addition, the luminescent particle layer can contain at least two types of luminescent particles.The luminescent particle layer can contain one or more types of other particles than the luminescent particles for example, coloring materials, phosphors, polymers, inorganic oxides, and the like, the luminance can be increased "as much as possible when the particles consist of the luminescent particles. For example, the luminescent particles which emit blue-green light and the pink coloring materials containing the complementary color in relation to blue-green (for example, particles containing rhodamine 6G, rhodamine B, etc.) are mixed, and forms the white luminescent layer. The "contact layer" can be formed by applying a polymerizable liquid containing polymerizable monomers or oligomers on the opposite surface of the coating film and thus polymerizing it. The containing monomer or oligomer liquid has sufficiently low viscosity; being able to fill the depressions certainly. _ The viscosity of the polymerizable liquid (a ° C) is usually between 1 and 100,000 centipoise, preferably between 5 and 80,000 centipoise, in particular between 10 and 50,000 centipoise. When the viscosity is too low. the contact layer having sufficient thickness can not be formed, and the bonding properties tend to deteriorate. When the viscosity is too high, the depressions can certainly not be filled. In the present, the viscosity of the liquid is measured using a Brookfield type viscometer with the No. 2 rotor at 60 rpm. Alternatively, an initial charge is first covered over the opposite surface of the coating film, and then the polymerizable liquid is applied.

The non-polymerized contact layer (revived layer) is formed in such a thickness that the depressions are filled, and the substantially smooth liquid surface is formed. When the thickness of the coated layer is too thin, the bonding properties of the contact layer to the EL device and the coating film tend to deteriorate. The thickness of the contact layer (a distance from the opposite surface of the coating film except depressions to the flat surface of the contact layer) is usually between 1 and 100 μm. The liquid surface of the cover layer formed on the opposite surface of the film of The coating is flattened prior to the provision of the EL device (or the transparent conductive layer). For example, the liquid surface can be flattened allowing a flattened free surface of a free film in contact with the surface of the polymerizable liquid which has been applied to the opposite surface of the coating film, and emptying the liquid while pressurizing it through of the release film so that the coated layer is formed. The pressurization facilitates the filling of the depressions with the liquid. - The pressurization can be carried out by passing the laminate of the retroreflective member, the cover layer and the release film between a pair of pressure rollers. During the pressurizing stage, the laminate can be heated. It is preferable to laminate another release film on the surface side of the retroreflective member to protect the surface of the retroreflective member and then to pressurize the laminate. The cover layer can be light-cured when the release film covering the coated layer is a very transparent film such as PET, polypropylene, polyethylene, and the like. The rays used for photopolymerization can be UV rays, electron beam, visible light, infrared ray induction, and the like. A dose of the beam to be irradiated is selected at a level at which the contact layer sufficiently solidifies, and the coating film and the EL device can be attached without delamination. For example, in the case of "UV rays, the dose is between 1 and 10 J / c 2. .7 Then, the release film is removed from the substantially flat surface of the formed contact layer and the EL device placed on the substantially flat surface with joining the light emitting surface of the EL device to the substantially planar surface.For example, the EL device can be formed, forming the transparent conductive layer, which is in contact with the contact layer and then laminated consecutively the elements of the EL device, such as the luminescent layer in the transparent conductive layer In addition to the coating method using the rollers as described above, the layer coated prior to the polymerization can be applied by methods using knives, rods, dies, and the like It is not necessary to use the release film when the surfaces of tools such as rollers, bar ras, and the like have sufficient release properties. Alternatively, the contact layer which is bonded to the coating film and the EL device can be formed by polymerizing the coated layer to allow the transparent conductive layer or the light transmitting film to have the transparent conductive layer in contact with the Liquid surface of the coating layer The monomer or oligomer contained in the above polymerizable liquid can be a polymerizable compound such as (meth) acrylates., epoxy compounds, cyanoacrylate compounds, and the like. Preferably, the (meth) acrylates substantially comprise the polyfunctional acrylate compounds, since the crosslinked density of the contact Yapa after increasing the polymerization, the dimensional stability improves with time, and the detachment of the contact layer caused by its contraction or expansion can be effectively prevented. 7 The polymerizable liquid, if desired, can contain various additives. For example, photopolymerization initiators can be added to increase the reactivity. Coupling agents such as silane coupling agents can be added to improve the adhesion properties. The coupling agent may be contained in an amount of between 0.1 and 10 parts by weight per 100 parts by weight of the polymerizable compound. In addition, "inorganic colloidal particles such as antimony pentoxide, zirconia, and the like can be added to increase the refractive index of the contact layer." Other additives such as diffusely reflecting particles can be added, "conductive particles, surfactants, light absorbers. UV, antioxidants, antifungal agents, rust preventatives, moisture absorbers, colorants (including fluorescent colors), matches, and the like, unless they damage the effects of the present invention. The term "polymerizable" includes "curable" and "crosslinkable" as the synonyms. The polymerizable liquid may be either heat curable or moisture curable. __ The contact layer may be formed of a non-polymerizable polymer, unless the effects of the present invention are damaged. In addition, the contact layer may include a plurality of layers that transmit light.

Application of the Retroreflective Sheet The retroreflective sheet of the present invention is adhered to a signal plate substrate by means of the adhesive provided on the opposite surface of the EL device, and used to "form a retroreflective signal plate." Examples of such an adhesive They are acrylics, polyurethanes and epoxy resin adhesives.When the EL device having the white luminescent layer is used, the whiteness of the background for the signals formed on the surface of the retroreflective sheet is increased. the same level between day and night.The visibility does not change at night substantially if the EL device is on or off.In addition, the appearance of the signal formed with transparent colors is improved.The EL device can emit light by joining a terminal pair, which has been connected to the transparent conductive layer and the posterior electrode respectively, to a source of p oder and applying a voltage to the device. It can be used as the source of power, cells such as dry cells, batteries, solar cells, etc., or an alternating current is provided to the EL device from a power line through a transformer, which alters the voltage or frequency or change the current between alternating current and direct current. The frequency of the alternating current is normally between 50 and 1000"Hz. The applied voltage is normally between 3 and 200 V. The EL type laminated device has a high efficiency of light emission, and therefore emits light at a low voltage which is necessary for a conventional type of dispersion.

Examples Example 1 This non-limiting example illustrates a retroreflective sheet comprising the device Laminate type 3 having the structure of Figure 2, and a retroreflective member 10 having the structure of Figure 1, which is attached through the contact layer 4.

Retrorreflective Member Production A resin film, which is a precursor of a coating film, was placed on an opposite surface (having cube corner prisms) of a cube corner re-reflective element having the transmission of light from the 100% opposed surface, at a certain distance from the surface of the film facing the opposite surface of the retroreflective element, and embossing it to form "sealing" projections Thus, a retroreflective member having a plurality of sealing cells was obtained by The temperature of an embossing roller was 260 ° C, and a cut-off pressure was 4.2 kg / cm2 The previous retro-reflective element was molded from a polycarbonate resin according to the method described in JP-A-6- 501111. The resin film was made from a transparent polyester that has a light transmission of 90.2% .The shapes of a plurality of cells were substantial. the same and all the squares, when viewed from the surface of the retroreflective element, and an area of a cell (an area surrounded by the sealing projections when viewed from the surface of the member) was 10 mm2. The total area occupied by the sealing projections was 38% of the total opposite surface of the retroreflective element. Then, a clear colored polymethyl methacrylate film of impact strength grade as a top film (a protective film) was fused to the surface of the retroreflective element to improve weathering resistance. The complete light transmission of the laminate of the three layers of the above component from the side of the coating film was 89.5%, and the total thickness was approximately 300 μm.

Formation of the Contact Layer The polymerizable liquid having the following composition was applied on the opposite surface of the coating film of the above retroreflective member, and a coated layer that filled the embossed marks (depressions) and having a flat liquid surface formed by The following method: Composition of Polymerizable Liquid Hidantoin Hexaacrylate 58% by weight 1,6-Hexanediol Diacrylate 38% by weight Irgagure 651 (light-curing initiator) 2% by weight Silane coupling agent ("KBM-603" available from Shinetsu Silicone) 2 % by weight First, the "polymerizable liquid (viscosity of 205 centipoises) was provided at an edge of the opposite surface of the coating film, and the retroreflective member was interposed between a pair of PET release films and passed between a pair of rollers of the In this case, the polymerizable liquid was emptied onto the opposite surface of the coating film, formed after the cover layer of the polymerizable liquid was polymerized, and the contact layer, which it was attached to the coating film and had a flat surface formed from the liquid surface.The cover layer was polymerized by irradiating YV light through the PET release film.The light source was a high pressure mercury lamp available under the designation JP-200-EXC of ORC Kabushikikaisha, the irradiation time was approximately 3 minutes, and the total dose was approximately 3.8 J / cm2 After the polymerization, the PET release films were peeled off. The thickness of the contact layer (the distance from the opposite surface (except depressions) of the coating film to the flat surface of the contact layer) was approximately 10 μm. The transmission of light from the laminate of the contact layer and the retroreflective member of the lateral contact layer was 86.5%.

Lamination of EL Device On the flat surface of the contact layer of the laminate which had been previously formed, a transparent conductive layer, the luminescent layer (having a support layer, a luminescent particle layer and an insulating layer), and The subsequent electrode was laminated in this order with these layers being joined, by the following procedures, and an EL device was assembled. Accordingly, a retroreflective sheet of this Example was obtained, which comprises the retroreflective member, and the light emitting surface of the EL device was obtained from which it was attached to the flat surface of the contact layer. A conductive layer! ITO (indium tin oxide) was laminated by electronic deposition. The thickness of the ITO layer was 100 nm, and the resistivity of the surface was 90 O / square. Separately, a paint to form a support layer was prepared by uniformly mixing and dissolving a polymer having a high dielectric constant (a tetrafluoroethylene-hexafluoropropylene vinylidene fluoride copolymer available under the trade designation THV 200 P from Dyneon, St. Paul, MN , which has a dielectric constant of 8 (at kHz) and a light transmission of 96%) in ethyl acetate with an ordinary mixer The solid content of paint was approximately 25% by weight - The paint to form the layer of support was applied to the ITO layer, then, the luminescent particles are dispersed over the applied paint substantially in a single layer of the previous state for "" the drying of the paint and fixed in the paint so that approximately 50% of the " "" background diameter. After that, the paint dried up. _The paint was applied with a knife coater, and the particles dispersed immediately after the application of the paint. The "drying conditions include a temperature of about 65 ° C and a drying time of about one minute." The total dry thickness of the support layer and the luminescent particle layer was 40 μm The luminescent particles were luminescent particles of ZnS (commercial designation: S-728 made by Osram Sylvania, average particle size, approximately 23 μm) Then, a paint to form an insulating layer was applied so that the paint covered the layer of luminescent particle and dried, and an insulating layer was formed. Therefore, a bonded structure was formed, in which the luminescent particle layer is embedded in both insulating and supporting layers and substantially no bubble occurs at the interfaces between each pair of layers. The paint to form the insulating layer was prepared in the same manner as for the paint to form the support layer except that a polymer having a high dielectric constant (THV 200 P described above), the insulating particles (titanate of barium manufactured by Kanto Kagaku) and ethyl acetate. The weight ratio of the polymer to the insulating particles was 100: 80, and the solid content of the paint was approximately 38% by weight. The paint was applied with a knife coater, and the drying conditions included at a temperature of about 65 ° C and a drying time of about one minute. The dry thickness of the laminate of the support layer, the luminescent particle layer and the insulating layer was 45 μm. Finally, a back electrode layer made of aluminum was laminated to the insulating layer by vacuum deposition, and an EL device was obtained as the film form of the present invention. In this stage, the vacuum deposition was carried out using a vacuum deposition apparatus "designated EBV-6DA (manufactured by Ulvac) under reduced pressure of 10 ~ 5 Torr or less for 5 seconds.

Light Emission of the EL Device. Respective terminals were attached to the transparent conductive layer and the back electrode layer of the EL device of this Example which had been prepared by cutting the device in the form of a sheet in a 100 mm x 100 mm square, and connected to a power source. (Commercial designation: PCR 500L manufactured by Kukusui Electronic Industries, Ltd.). Then, the alternating voltage was applied to the device under conditions of 120 V, 600 Hz. The light was emitted brightly and uniformly over the entire surface that emits light from the leaf. The luminance (luminance that emits own light) was measured, and the result is shown in Table 1. The luminance was measured by placing the retroreflective sheet in a dark room and measuring a luminance at a distance of 1 meter from the surface of the film higher using a luminance meter (commercial designation: LS 110 manufactured by Minolta).

Retrorreflective Reflection Luminance The reflection luminance of "the retroreflective sheet of this Example is measured when the EL device is turned off," according to JIS Z 8714 using a Model 920 designed apparatus manufactured by Gamma Scientific The result is shown in the Table 1.

The result shows that the retroreflective sheet of this Example achieved the luminance of sufficiently high retroreflective reflection.

Comparative Example 1 A retroreflective sheet of this Comparative Example was produced in the same manner as in Example 1 only that no contact layer was formed, and its same luminance emitting light and reflection luminance were measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A retroreflective sheet of this Comparative Example was produced in the same manner as in Example 1 only that no contact layer was formed, and the "ITO layer was formed by the following paste coating. in this Comparative Example it is available under the trade designation SC-100 manufactured by Tohoku Kako This paste was covered on the surface of the coating film with a bar coater and dried, and an ITO layer was formed.

The ITO layer formed by this method could not fill the depressions in the opposite surface of the coating film and several gaps were formed from the remaining depressions. A luminance emitting its own light and a reflection luminance of "this retroreflective sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Table 1 Luminance that Emits Light and Luminance of Reflection of Retruereflective Sheets The present invention provides a retroreflective sheet that emits light having a sufficient retroreflective reflection luminance (e.g., 500 cd / light / "), and a luminance that emits light which is increased to a level where the visibility is through. Gave Even enough night when no external light source is available, and no retroreflection occurs. The full descriptions of all patents, patent applications, and publications were incorporated herein by reference as if they will be incorporated individually. The various modifications and alterations of this invention will become clear to those skilled in the art, and it should be understood that this invention is not unduly excluded by the illustrative embodiments cited therein.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention is the conventional one for "the manufacture of the objects or products to which it relates. above, the content is claimed as priority in the following:

Claims

RE IVIN IC C IONS

1. A retroreflective sheet that emits, light characterized in that it comprises: "A. a retroreflective member comprising (i) a retroreflective element that transmits light" having a substantially planar surface, and an opposing surface in which a plurality of prismatic projections they place, and (ii) a coating film comprising a film that transmits light, which has protrusions by the embossing and has, on its surface, sealing projections which is attached in part to the opposite surface of the retroreflective element. so that the prismatic projections are confined while the surfaces of the prismatic projections have interfaces with an air and form a plurality of sealing cells, and B. an "electroluminescent" device which has a surface that emits substantially flat light that extends substantially to the total area of the opposite surface of the coating film, where the retro sheet The reflector that emits its own light additionally comprises a contact layer that emits light which fills the depressions formed by the embossment on the opposite surface of the coating film and substantially joins the total area of the opposite surface of the coating film, and also substantially to the total area of the surface that emits light from the electroluminescent element.

2. The retroreflective sheet that emits own light according to claim 1, characterized in that the retroreflective element that emits light has a light transmission of at least 70%.

3. The retroreflective sheet that emits own light according to claim 1, characterized in that the coating film has a light transmission of at least 20%.

4. The retroreflective sheet that emits own light according to claim 1, characterized in that the contact layer has a light transmission of at least 30%.

5. The retroreflective sheet that emits own light according to claim 1, characterized in that it additionally comprises a protective film on the substantially flat surface of the retroreflective element that emits light.

6. The retroreflective sheet that emits own light according to claim 1, characterized in that the sealing projections which are partially joined to the opposite surface of the retroreflective element form an adhesion area of about 10% to about 85% of the total opposite surface of the retroreflective element.

7. A method for producing a sheet that emits own light as claimed in claim 1, characterized in that it comprises the steps of: A. placing a resin film which is a precursor of the coating film with its surface opposite the opposite surface of the retroreflective element by leaving a specific distance from the opposite surface of the retroreflective element, B. Embossing the resin film of its opposite surface to make protrusions on part of its surface and forming the sealing projections which join the opposite surface of the retroreflective element, where the retroreflective member having the plurality of sealed spaces is formed, C. forming a coated layer having a substantially flat liquid surface by applying a polymerizable liquid to the opposite surface of the coating film and filling the depressions formed by the embossment, D. polymerize the coating liquid and forming a contact layer having the substantially flat surface which is formed from the substantially flat liquid surface and attached to the coating film, and E. placing an electroluminescent element on the substantially flat surface of the contact layer so that its surface that emits light is in contact with the contact layer.