MXPA99008652A - Wide incident angle reflective plate - Google Patents

Abstract

A reflective plate (10) is disclosed, comprising a substrate (1), a retroreflective sheet (2) adhered to the surface of said substrate andhaving substantially flat base portions (3) covered with said retroreflective sheet (2), the retroreflective sheeting having retroreflective elements and a light transmissive cover layer;and a plurality of projections (4) covered with said retroreflective sheet and present on the corners of regular polygons that are arranged to form a regularly repeated pattern, wherein the arrangement of the projections (4) satisfies the relationship 0.05<h/P<0.60.

Description

REFLECTING PLATE ANGLE OF GREAT INCIDENT OPENING Technical Field The present invention relates to an incident wide-angle wide-angle reflector plate comprising a laminate of a substrate and a retroreflective sheet adhered to the substrate surface, the plate of which is used to improve visibility at night.

Background of the Invention The structures and production methods of the retroreflective articles, such as retroreflective sheets comprising a plurality of reflection rims which are fixed in a support layer having a raised surface, these are discovered in a variety of publications. Japanese patents JP-A-55-65524 and JP-A-57-193352 disclose methods which include the steps of applying a foamed component to a flat substrate surface in a directed form and coating with a resin on the surface of the substrate. substrate to make a support layer. On the support layer, glass beads are dispersed REF. 31261 transparent and then the paint for the backing layer is dried and cured to fix the glass beads to the backing layer. Finally, the substrate is heated to spread the foam component, thus producing projections. JP-A-53-46363 and JP-A-53-46371 disclose methods which include etching an elaborate substrate of thermoplastic resins to make an embossed surface and coating it with a paint containing resins in a sufficient thickness, as for filling the portions that are intended to obtain a support layer having a flat surface. The transparent glass rims are etched onto the surface of the support layer and then the resin which is in the support layer is cured to fix it to the glass rims that are in the layer. Finally, the sheet as a whole is heated in such a way that the surface of the substrate is recovered from a flat state to form an embossed surface having various heights corresponding to the difference between the coated thicknesses of the substrate resins. JP-A-57-10102 discloses a method that includes coating with a paint that shrinks and forms wrinkles until they dry on a substrate, spreading glass beads on the fresh paint and then, heating and drying the paint to form projections to which the glass beads are fixed. U.S. Patent Publications Number 4,069, 281 and Japanese JP-A-58-237243 disclose retroreflective sheets that are produced by making projections of a paint containing resins onto a substrate, etching glass beads in the projections, prior to to dry and cure the projections and then cure the projections to fix the glass flanges. British Patent 2,251,091 discloses a retroreflective sheet produced by adhering transparent glass beads to an aluminum layer having a plurality of prominences. JP-A-58-2080041 and JP-B-7-84726 disclose methods for producing retroreflective sheets that include the steps of forming a backing layer from a thermoplastic polymer, and etching parts of transparent glass rims. on a surface of the support layer. Thus, the support layer is engraved from one side in which, the flanges have been engraved and the projections in which the parts of the flanges are engraved, and also in the depressions in which the flanges are completely etched .

The methods and structures described in the above references, do not use any layer of light transmitting cover, which covers the surfaces of the flanges. JP-Y-62-41804 discloses a reflective sheet having projections which are intended to prevent burrs in it. This reflective sheet that is produced, for example, by adhering a retroreflective sheet having a light-transmitting cover layer, which covers the ridge surfaces for the surface of the substrate and etching the substrate from its back face to form projections on the substrate surface. However, in general, the size of the projections that are formed by avoiding burrs is relatively sticky, for example, a width of 2 mm and a height of 1 mm. Moreover, this utility model publication does not teach any favorable reflection characteristics for the incident light at an angle of large incident aperture coming from an angle of small incident aperture (a direction close to the normal line of the reflecting plate) to a incident large-angle angle (a direction close to the reflective plate) ie, dimensions and configurations of the projections for a reflective sheet having good reflection characteristics of incident large-angle angle.

Publications WO 97/01677 and WO 97/01678 disclose retroreflective materials which comprise raised portions in the form of a reflecting wall and flat areas which are covered with a retroreflective sheet of the lens type, although they are not produced by means of of engraving. However, these publications do not suggest improvement to easily remove water droplets or solid foreign substances adhering to the flat areas. In view of the relative disadvantages of the methods and structures described above, it is important for the reflecting projections to have predetermined dimensions and patterns for the formation of a plate-like reflective material with excellent incident large-angle angle reflection characteristics. This is particularly important for the improvement of reflection characteristics against light having a relatively high angle of incidence, for example, 70 degrees or greater from the normal line, up to the reflecting surface. The reflector plates must have suitable properties for outdoor use, when they are used as construction parts of signals used outdoors. That is to say, it is reguired that these have properties in which, their reflective luminosity decreases rarely when drops of water Adhere to the reflective plates and in which foreign substances such as dust are easily removed if they adhere to the reflecting plates and in which they maintain sufficient reflective luminosity during use. An object of the present invention is to provide an incident large-angle angle reflective plate, which has both good incident angle large-angle reflection characteristics, and outdoor use characteristics.

Brief Description of the Drawings The present invention will be described in greater detail when referring to the accompanying figures, in which: Figure 1 is a cross section of an embodiment of the reflective plate of the present invention; Figures 2A, 2B and 2C show another embodiment of the configuration of the projections of the reflecting plate; Figure 3 shows the configuration of the projections of the reflective layer produced in Example 1; Figure 4 shows the configuration of the projections of the reflective plate produced in Example 2; Figure 5 is a cross section of the material for marking roads in transit, used in Comparative Example 1; and Figure 6 is a cross section of the reflecting plate used in Comparative Example 2.

Detailed description of the invention The present invention provides an incident large-aperture angle-type reflective plate 10 comprising a laminate having a substrate 1 and a retroreflective sheet 2 adhered to the surface of the substrate and having substantially flat base portions 3 covered with the retroreflective sheet 2, and a plurality of projections 4 which are separated by means of the flat base portions, covered with the retroreflective sheet and present in the slivers of the regular polygons which are arranged to form a pattern repeated regularly. In this configuration, the retroreflective sheet 2 comprises retroreflective elements and a layer of light transmitting cover that covers the surfaces of the elements retroreflectors and the configuration of the projections 4, which satisfies the following Equation I.

Equation I: 0.05 < h / P < 0.60 where P is a distance between the two most distant strands of a polygon and where h is the height of the projection measured from the surface of the base portion. The characteristics for outdoor use can be improved when the retroreflective sheet 2 has a layer of light transmitting cover that covers the surfaces of the flanges or the retroreflective elements of cube slime. The characteristics of the incident large-angle angle reflection and the characteristics of outdoor use are improved both, when the configuration and the cross-sectional size of the reflecting projections 4, satisfy the above equation. The luminosity of reflection in relation to light at an angle with a relatively high aperture, may increase, as the density of the projections accommodated in the horizontal plane increases, when the projections are accommodated in the slivers of semi-straight or semi-straight triangles. eguiláteros in the horizontal plane of the reflector plate 10.

Moreover, the reflective plate has an improved non-directionality, that is, the properties to exhibit sufficient reflection brightness against the incident from any direction of the horizontal plane. The configuration of the projections on the slivers of the semi-eagle triangles (forming rhombuses) is particularly appropriate for improving non-directionality. The incident large-angle angle reflecting characteristics are effectively improved, when the vertical cross-sections of the projections 4 have an arcuate curved surface, which is convexly upward. In addition, the deformation of the projections, effected by the external force, is effectively avoided, when the projections 4 are formed by means of recording and stopping, hollow spaces within them. Moreover, solid foreign substances can be easily removed from the surface of the reflecting plate. Up to this point, the projections preferably have shapes in which their vertical cross sections include an arc or an ellipsoidal arc. A solid form of said projections includes a cone with a rounded top (apex). When the reflective plate 10 has a tenth layer provided on the rear face of substrate 1, and 1 A coating comprising a plastic film to protect the adhesive layer is preferably produced as follows. A flat substrate made of moldable metal or resin is provided as a substrate, a laminate is formed by applying a retroreflective sheet and an adhesive layer protected by a coating comprising a plastic film on one surface and the rear face of the substrate, respectively , and the laminate is thus etched by means of pressing a recording tool having a plurality of projections towards the laminate, through the coating to form the projections of the reflective plate. This method can accurately and easily form the projections 4 having the desired shapes, dimensions and configuration. The adhesive layer is easily laminated by means of any conventional application method, such as coating before the formation of the depressions on the rear face of the substrate. The rupture of the coating during etching can be effectively avoided when the coating comprises a plastic film.

Reflective Plate of Angle of Great Opening Incident The incident large-angle angle reflector plate (sometimes referred to as "reflective plate") is a reflective plate having a reflection brightness at a sufficient level, relative to the incident light coming from a direction close to the normal line of the horizontal plane of the reflecting plate, and a reflection brightness at a visible level (for example 1.5 CPL or higher) in relation to incident light from an inclined direction near the horizontal plane of the reflecting plate, when the reflective plate is placed horizontally. In other words, the reflective plate of the present invention has sufficient reflection properties against the incident light in the range of a large incident angle, that is, the reflection brightness does not significantly decrease, for example, to 1 CPL or less, when the direction of the incident light is changed from a direction close to the normal line of the horizontal plane, towards a direction close to the horizontal plane. The range of incident angle in which the reflective plate of the present invention has sufficient reflection properties, is at least between 0 and 75 degrees, and between 0 and 86 degrees in a preferred embodiment. East angle is an angle from the line normal to the horizon plane of the base portion of the reflecting plate. Equation I represents a relation between the parameters necessary to design the best size and the configuration of the projections 4.1a ratio h / P in the Equation I corresponds to such people of the angle (90-?) In Figure 1, that is, tan (90-?). Accordingly, the upper and lower limits in Equation I mean that the upper and lower limits of the angle? it is approximately 60 degrees and approximately 87 degrees, respectively. The angle ? is an angle (in degrees) that exists between the line extending from the center of a projection 4 (ie, the span of the regular polygon that forms the pattern configuration) toward the vertex of projection 4, adjacent to the said projection (i.e., an intersection between the normal line to the horizontal plane of the base portion passing through the center of the configuration of the outer periphery of the projection), and the normal line to the base portion 3 extending from the the configuration (see Figure 1). This angle? it is a measure to designate the incident maximum angle in which, we have sufficient reflection luminosity. When the ratio h / P in the Equation I is 0.05 or less, that is, the angle? is approximately 87 degrees or greater, the lightness of reflection against light which has a relatively large angle of incidence, is decreased. When the ratio h / P in Equation I is 0.60 or greater, that is, the angle? is approximately 60 degrees or less, the incident angle at which sufficient reflection brightness is obtained can not be high enough, for example, 70 degrees or greater. The h / P ratio is preferably between 0.07 and 0.47 (being? between approximately 86 and 65 degrees), in particular between 0.08 and 0.30 (being? approximately between 85 and 73 degrees). The distance P is usually 4 mm or greater. When P is less than 4 mm, the reflection properties in relation to the light which is in the incident angle of high aperture, can not be improved. When P is very large, the configuration density of the projections decreases and thus, the effect to improve the reflection properties in the incident angle of high aperture can be deteriorated. The variable P is preferably within the range of between 8 and 30 mm, in particular between 10 and 25 mm. The height h is usually 0.5 mm or less. When h is less than 0.5 mm, the properties of reflection in relation to the light that is in the incident angle of high aperture, it can not be improved. When h is very large, the retroreflective sheet can be broken during the formation of the projections. The variable h is preferably within the range between 1 and 10 mm, in particular between 1.5 and 5 mm. The variable D in the figures is the width of the projection that exists between the intersections of the projection 4 and the adjacent base portions in the vertical cross section. D is usually and at least 2 mm. When the size D is very sticky, the properties of reflection in relation to the light which is in the incident angle of high aperture, can not be improved. When D is very large, the configuration density of the projections (which will be explained in detail) decreases and thus, the effect to improve the reflection properties in the incident angle of high aperture, may deteriorate. The variable D is preferably within the range between 3 and 20 mm, in particular between 5 and 15 mm. The configuration of the projections 4 follows the pattern formed by means of regularly repeating one or more regular polygons and the projections 4 are present on all the slivers of the polygons. All the projections are present independently and this configuration of projections makes it easy to remove foreign substances adhered to the reflecting plate. Each projection is preferably placed, such that the center of gravity of the lower figure (a horizontal cross section that interacts with the base portion), for example, the center of a circle, coincides substantially with the polygon's star (a center of the projection configuration). The center of gravity of the geometric diagram can be obtained by means of known mathematical methods. The figure of the polygon is not limited, as long as it satisfies Equation I. For example, the figure can be an eguilátero polygon (for example, a square, a pentagon, a hexagon) or a rhombus composed of two eguilarial triangles that are joined on each of its sides respective, in the horizontal plane inclining to the base portion. In some cases, the configuration pattern includes two or more different polygons and thus, a plurality of P values is obtained. In such cases, all P values preferably satisfy Equation I to improve the reflection characteristics of the incident angle. high opening. The configuration density of the projections depends on the D and P values mentioned above and are usually between 5 and 150 projections per 25 cm, preferably between 10 and 80 projections per 25 cm in the horizontal plane, including the base portions. When the configuration density of the projections is very sticky or very large, the properties of reflection in relation to light at an incident angle of high aperture, may deteriorate. The configuration density is the number of projections that are included completely within a 25 cm2 square. The solid form of the projections can be a dome, dome whose head is cut horizontally, a pyramid, a truncated pyramid, the cone, the truncated cone, a prism, a cylinder and the like. Among these, the cone (whose vertex can be rounded) is preferred because of its easy engraving. The two or more projections can have different solid shapes, as long as the effects of the present invention are sustained. The dome shape includes a dome that has a horizontal semcular or ellipsoidal cross section. When the projections include the projections which have an ellipsoidal horizontal cross-section, they can be accommodated as shown in Figures 2A, B and C. The configuration of Figure 2A is preferable to increase the reflection brightness in relation to the light which is in the incident angle relatively high aperture. In Figure 2B, the projections are accommodated, in such a way that their wider reflection planes are towards the direction of the date and two adjacent productions are placed more frequently in this direction. Thus, the large-aperture incident angle reflection properties are more effectively obtained when the reflecting plate is illuminated by light along this direction. The substrate is usually made of metal or plastic. Among these, metals are preferred. soft or plastic with good, expandability, since these can easily be recorded and can be easily formed with accurate projections. Preferred examples of the soft metals are aluminum, copper, silver, gold and the like and preferred examples of soft plastics are polyethylene, polypropylene, polyvinyl chloride, polyurethane and the like. The thickness and tensile strength of the substrate are not limited, provided that the effects of the present invention are obtained. When the reflective plate is formed by etching as will be explained below, the properties of the substrate will preferably be selected as follows. The thickness of the substrate is preferably between the range of 0.05 and 1 mm for metals or within the range between 0.1 and 5 mm for plastics. When the thickness is too sticky, the substrate can be broken during the formation of the projections by means of engraving. When the thickness is very large, the formation of the projections by means of engraving can be made difficult. The tension force is preferably between 1 and 10 kg / mm2, more preferably between 2 and 9 g / mm. When the tension force is less than 1 kg / mm2, the substrate may be broken during engraving. When it exceeds 10 kg / mm2, the engraving can become difficult.

Retroreflective Sheet The retroreflective sheet used in the present invention is a sheet comprising a cover layer and reflective elements on the surfaces in which they are not exposed. The cover layer can be formed by means of an acrylic resin, polyester resin, fluororesin, polyolefin resin, polyvinyl chloride resin and the like. The transmission of light from the cover layer within the entire wavelength range is usually, by at least 80%. Examples of the retroreflective sheet having a cover layer are SCOTCHLIGHT # 580, # 3810 and # 1570 (all available from the Minnesota Mining and Manufacturing Company of St. Paul, Minnesota (3M)) and the like. These retroreflective sheets comprise a reflector element which has glass flanges and reflective films placed in focal points of the flanges, the surfaces on which the flanges are covered with the cover layer. The retroreflective sheet of encapsulated lens type is preferably to increase the reflection luminosity. Also, greyhound prisms made of plastic are preferable as the elements of reflection. The properties of the retroreflective sheet, such as stretching to the point of rupture, strength to the point of rupture and thickness are not limited, provided that the effects of the present invention are obtained. When the reflective plate is formed by etching, these properties are preferably selected as follows. Stretching to the point of rupture is preferably between 100 and 300%, more preferably between 120 and 280%. When stretching to the point of rupture exceeds 300%, the reflective plate tends to wrinkle during etching. When stretching to the point of rupture is less than 100%, etching can become difficult. The force at the point of rupture is preferably between 1.0 and 10.0 kg / 25 mm, more preferably still between 3.0 and 7.0 kg / 25 mm. When the force at the point of rupture is less than 1.0 kg / 25 mm, the retroreflective sheet can be broken during engraving. When the force to the point of rupture exceeds 10 kg / 25 mm, the engraving may become difficult. The thickness is preferably between 10 and 750 μm. When the thickness is less than 10 μm, the retroreflective sheet can be broken during engraving. When the thickness exceeds 750 μm, the engraving can become difficult. The substrate and the retroreflective sheet are adhered with any conventional adhesive, such as acrylic adhesives, polyolefin adhesives, polyurethane adhesives, silicone adhesives, epoxy resin adhesives, and the like. The adhesive can be a pressure sensitive adhesive or a hot melt adhesive. The pressure sensitive adhesives are preferable, since they facilitate the production of the reflective plate by means of recording, due to its high volatility. The thickness of the adhesive is usually between 5 and 50 μm. The adhesive layer, formed on the back face of the substrate, is used to adhere the reflective plate to an adherent such as a guardrail. The adhesive used for the adhesive layer may be the same as that exemplified above. Again, the pressure sensitive adhesive is preferable, since it facilitates etching, due to its high volatility. The thickness of the adhesive layer on the back face of the substrate is usually between 5 and 50 μm. A Cape The primer is preferably formed between the back face of the substrate and the adhesive layer, when the substrate is made of a plastic having relatively few adhesion properties, such as polyethylene. The coating for protecting the adhesive layer is preferably an adhesive paper comprising a laminate of a paper sheet and a resin sheet such as polyethylene, polypropylene and the like, and a film of a resin such as polyethylene terephthalate, polyethylene, polypropylene and the like. These coatings facilitate the engraving since they rarely break. In particular, a polyethylene resin film having good expandability is preferable, when the reflective plate is produced by etching. Examples of said polyethylene resin are low and very low density polyethylene resin, ethylene-methyl methacrylate copolymers, mixtures of polyethylene and polypropylene and the like. The reflective plate of the present invention is preferably produced by etching, since the engraving can form compression, the projections having particular shapes, dimensions and configurations. The engraving is carried out by means of pressing a recording tool that has projections with shapes, dimensions and configurations designed appropriately for the back face of the substrate. The shapes, dimensions and configurations are designed in such a way that they correspond to those projections of the reflecting plate. The pressure during engraving is usually between 1 and 100 kg / cm2, preferably between 20 and 80 kg / cm. The pressure is generated by means of oppression operations, such as mechanical pressure, suction pressure and the like. As a recording tool, a pair of tools is used, a first tool that __ comprises a plate or roll that has the projections on its surface and a second tool that is in contact with the surface of the retroreflective sheet. The second tool may be a tool having depressions to receive the projections of the first tool or a tool having a flat, narrow surface of a material that deforms when the first tool is pressed from the back face of the substrate. The material for the last, second tool, can be rubber, elastomers, etc. In the production method comprising engraving, the same engraving conditions and tools can be used, when the laminate comprises the substrate which is transported on its surface and on the face to the retroreflective sheet and the adhesive layer, which is protected with a coating, is formed respectively and thus, the engraving tool having a plurality of projections, is pressed towards the laminate coating to form the projection onto the laminate. The engraving may be carried out after images, such as characters or typography, signs or symbols, etc., are printed on the surface of the cover layer of the retroreflective sheet. Alternatively, the reflective plate of the present invention can be produced by means of placing the retroreflective sheet on a substrate, having the projections already formed and thus, adhering by means of pressure to the substrate and to the reflecting sheet under reduced pressure.

Applications of Reflective Plates The reflective plate of the present invention can improve the visibility at night of materials which are illuminated by automobile headlights, at an incident angle of high aperture, for example, traffic signs, guardrails, signaling boards, plates with images and the like. , which are placed on roadsides, curved areas, inside tunnels, etc. Is say, the drivers can identify the materials to which, the reflective plates are attached from relatively remote distances.

EXAMPLES Example 1 A soft aluminum plate (catalog number: AlN30H-O available from TOYO ALUMINUM Co., Ltd.) was used as a substrate and a closed lens type reflecting sheet (product # 580 available in 3M) was used as a sheet retroreflective. The aluminum plate had a thickness of 0.08 mm and a tensile strength of approximately 8 kg / mm and the retroreflective sheet had a thickness of 170 μm, a stretch to the breaking point of 200% and a force to the breaking point of 4.8 kg / 25 mm. The retroreflective sheet was adhered to the substrate with a layer of acrylic adhesive formed on the back side of the retroreflective sheet. On the back side of the substrate, a layer of acrylic adhesive with a thickness of approximately 25 μm was laminated and a protective coating made of a polyethylene resin having a thickness of 90 μm. To produce the reflective plate of this Example, the above-formed laminate was etched as follows. A recording tool, having a plurality of projections, was pressed onto the coating on the back face of the substrate. They were used to record a couple of tools, the first tool having projections and the second tool having depressions to receive the projections of the first tool. The engraving pressure was approximately 70 kg / cm. The dimensions and geometrical pattern of the projections are shown in Figure 3. In this example, D was 6 mm, P was 14.1 mm, and h was 2 mm. Thus, the h / P ratio in Equation I it was 0.14. The distance P is measured in the direction indicated by the arrow B (the diagonal line of the table), X is the distance between the adjacent columns of the projections (10 mm, in the mode shown) and Y is the distance between the adjacent rows (10 mm, in the mode shown). The reflection luminosity was measured under the conditions shown in Tables 1 and 2. It was found that the reflector plate of this Example has both excellent characteristics of large incident angle angle and characteristics of outdoor use (anticorrosive). The reflection brightness in Table 1 was measured with a retroreflection meter, according to with JIS Z 8714, while that of Table 2 was measured with a MIROLUX 1, manufactured by TOSHIBA BALLOTINI.

Example 2 A reflecting plate was produced in the same manner as in Example 1, except that the projections were accommodated in the geometric pattern shown in Figure 4, ie, rhombuses (composed of eguilarial triangles) in which D was 6. mm, P was 20.7 mm and h was 2 mm. Thus, the h / P ratio in Equation I was 0.10. The distance P was measured in the direction indicated by the arrow C. The distance X is between the adjacent columns (12 mm, in the mode shown) and Y 'is the distance between two adjacent rows of equal lateral separation (20.7 mm, in the modality shown). The measured reflection luminosities are shown in Tables 1 and 2.

Example 3 A reflecting plate was produced in the same manner as in Example 2, except that the retroreflective sheet was changed by the encapsulated lens-type reflector sheet (product number 3870 J available in 3M). This reflector sheet of encapsulated lens type it had a total thickness of approximately 280 μm, a stretch to the breaking point of 200% and a force to the breaking point of 5.9 kg / 25 mm. The measured reflection luminosities are shown in Tables 1 and 2.

Example 4 A reflective sheet was produced in the same manner as that of Example 1, except that the dimensions and configuration of the projection were changed to D of 2.7 mm, P of 7.4 mm, h of 0.6 mm and so also, a h / P ratio of 0.08. The reflection luminosity in direction B was approximately 450 mcd / m when the angles, incident and observation were 86.5 degrees and 1.5 degrees, respectively.

Comparative Example 1 A # 380 road marking material (available in 3M) was used and the reflection brightness was measured in the same way as in Example 1. This road marking material had the same cross-section structure as in Figure 5. The Glass beads 100 were adhered to the lateral surfaces of the projections, which protruded above the base 102. This material was of the lens type exposed, without having any covering layer. A pressure sensitive adhesive layer 104 and a coating 106 were also provided. The results are shown in Tables 1 and 2.

Comparative Example 2 A SCOTCHLANE ™ # 6160 material was used, available in 3M and the reflection brightness was measured in the same way as in Example 1. This product had a cross section structure without any projection and the 100 'glass beads were scattered substantially in a single layer on the base 102 d such that the brightness of reflection relative to the light, at an incident angle of relatively high aperture, could be increased, as shown in Figure 6. This product was of the type of lens exposed without having any cover layer on the surfaces of the flanges. The results are shown in Tables 1 and 2.

Comparative Example 3 The same retroreflective sheet of encapsulated lens type was used, which was used in Example 3 and the reflection luminosity was measured therein. as in Example 1. The results are shown in Tables 1 and 2.

Comparative Example 4 The same enclosed lens type reflecting sheet was used that was used in Example 1 as such and the reflection brightness was measured in the same manner as in Example 1. The results are shown in Tables 1 and 2. The reflection luminosity in relation to the light that is in the incident angle of 75 to 85 degrees, was in this Comparative Example of less than a tenth in that of Example 1, since this reflective sheet did not have a reflection projection.

Table 1 Table 2 Notes: 1) The percentages that are in parentheses are retentions in relation to the values of the original states. 2) Water on the surface: the reflection luminosity was measured just after the water It was applied to a sample that was maintained vertically. Graphite dispersion: after the graphite powder was spread on a horizontally held sample, the sample was held vertically to remove excess graphite powder. Then, the reflection luminosity was measured. Rinsing after graphite dispersion: after the previous sample was washed with running water and dried, the reflection luminosity was measured.

It is noted that, with regard to this date, the best method known by the requested, to carry out the present invention, is that which is clear from the present, discovering the invention. Having described the invention as above, the content of the following is claimed as property.

Claims (1)

1. CLAIMS A reflective plate characterized by porgue comprises: a substrate; a retroreflective sheet adhered to the surface of the substrate and having substantially flat base portions, covered with the retroreflective sheet, the retroreflective sheet having retroreflective elements and a light-transmitting cover layer covering the surfaces of the retroreflective elements; and a plurality of projections covered by the retroreflective sheet and present on the slivers of the regular polygons which are placed to form a regularly repeated pattern, wherein the configuration of the projections satisfies the ratio 0.05 < h / P < 0.60 in which, P is the distance between the two most remote strands of a polyhedron and h is the height of the projection measured from the surface of the base portion. The reflective plate according to claim 1, characterized in that the retroreflective sheet includes microspheres. A reflective plate characterized by comprises: a substrate; a retroreflective sheet adhered to the surface of the substrate and having substantially flat base portions, covered with the retroreflective sheet, the retroreflective sheet having retroreflective elements of cube scintillate which are not exposed; and a plurality of projections covered by the retroreflective sheet and present on the corners of the regular polygons which are placed to form a regularly repeated pattern, wherein the configuration of the projections satisfies the ratio 0.05 < h / P < 0.60 in which, P is the distance between the two most remote strands of a polyhedron and h is the height of the projection measured from the surface of the base portion. A method for producing an incident large-angle angle reflective plate according to claim 1, characterized by comprising the steps of: providing a flat substrate made of a resin or expandable metal; forming a laminate by applying the retroreflective sheet and a layer of adhesive on a surface of the substrate; and etching to the laminate by pressing a recording tool which has a plurality of projections towards the laminate through a coating to form the projections on the reflecting plate.