JP2012047020A - Directional reflection material and building material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a directional reflection material and a building material using the same, which can effectively control irradiation light or reflection light of sunlight or the like.SOLUTION: A directional reflection material comprises a bearing layer, a reflective layer having a reflectance distribution, and a collective lens. Since the reflective layer of a retroreflective material has the reflectance distribution, the reflectance of incident light is varied depending on the incidence angle and the incidence direction.

Description

  The present invention relates to a directional reflective material capable of effectively controlling irradiation light such as sunlight or reflected light, and a building material using the same.

  In recent years, one of the global warming problems is the heat island phenomenon. The heat island phenomenon means that the temperature in an urban area is abnormally high compared to the surrounding suburbs. One cause of the heat island phenomenon is a decrease in light reflectance and an increase in heat absorption rate due to asphalt and concrete. As a countermeasure, a high light reflectivity material / paint that exhibits high reflectivity in the visible light region and the infrared region is employed on the outer wall of the building. Thereby, if the solar radiation is reflected efficiently, the amount of heat received by the building is reduced, so that the building is not warmed and the cooling load can be reduced.

  However, when a high light reflectance material or paint is used for the outer wall of a building, the light reflected from the wall surface is reflected back to the surroundings, and the adjacent building or road surface is warmed. For this reason, there exists a problem that the place which can be utilized is restricted. In winter, the amount of heat received decreases, so the heating load increases. For this reason, the energy for heating increases in winter.

  In order to solve the problem of reflection, attempts have been made to use retroreflective materials (see, for example, Patent Documents 1 and 2). A retroreflective material is a reflective material having a property of reflecting light incident from any direction in the incident direction. By using a retroreflective material on the outer surface of the building, the light from the sun that changes every moment can be reliably reflected in the direction of the sun without being reflected back to the surroundings. As a mechanism of the retroreflective material, a prism type by corner cube reflection and a spherical lens type by bead refraction are known. FIG. 7 is a diagram showing light reflection in a conventional spherical lens type retroreflective material. In the example of this figure, the reflective layer 21 is provided on the support layer 20, and a part of the condensing lens 22 is embedded in the reflective layer.

  When the retroreflective material as shown in FIG. 7 is used, the problem of reflection can be solved. However, the problem of increased heating load in winter cannot be solved. Further, due to the nature of the retroreflective material, for example, light from below such as a headlight of an automobile is reflected in the direction of the light source, so that there is a problem that the visibility is deteriorated. For this reason, there exists a problem that it can be used only in the location which cannot be seen from the road surface.

  If the reflectance can be controlled, the problem of increasing the heating load in winter and the problem of light pollution can be solved. Attempts have been made to control the reflectance of the optical reflector by the direction and angle of incident light (see, for example, Patent Documents 3 to 8).

  Patent Document 3 discloses a solar reflector installed on the roof surface of a building. On the surface of this sunlight reflecting plate, a plurality of long plate-like fins made of a light absorbing material are erected so that the longitudinal direction is the east-west direction, and a louver structure reflecting plate is disclosed. In the summer when the solar altitude is high, sunlight is reflected by the reflector between the fins. On the other hand, in the winter when the solar altitude is low, sunlight hits the fins directly and changes to heat on the fin surfaces. However, this reflector can be installed only on a horizontal surface such as a roof surface or the ground surface. For this reason, there exists a problem that it cannot install in the side of a building, the roof surface which does not have a horizontal surface, etc. Moreover, the reflection to the periphery cannot be prevented.

  Patent Document 4 discloses a light control structure in which an electrochromic layer following the shape of a substrate is provided on a panel, and the electrochromic layer is energized to switch between a retroreflective state and a heat collecting state that absorbs light. Is disclosed. However, since this light control structure needs to switch between the retroreflective state and the heat collection state by energization, the structure is complicated and the light resistance is poor. For this reason, there exists a problem that it is not suitable for using for the outer skin of large structures, such as a building.

  Patent Document 5 discloses a retroreflective material including a reflective layer and transparent microspheres using cholesteric liquid crystal as a reflective material for the reflective layer. However, since the retroreflective material uses cholesteric liquid crystal as the reflective material of the reflective layer, the reflectance cannot be set to have a distribution depending on the incident angle and the incident direction. In addition, cholesteric liquid crystals are expensive to use for the outer skin of large structures such as buildings, have a problem that they have poor light resistance and do not conform to the actual situation.

  Patent Document 6 discloses a skin material in which a retroreflective layer surface is laminated with a sheet having angle selective transparency in which a light shielding wall is installed in a transparent resin. However, in the angle selective transmission sheet, it is not possible to set the reflection directivity in which the reflectance is distributed according to the incident angle and the incident direction.

  Patent Document 7 discloses a method of forming a directional image that can be viewed with eyes within a range of a specific observation angle on a retroreflective sheet. However, it is not possible to set the reflection directivity in which the reflectance is distributed according to the incident angle and the incident direction.

  Patent Document 8 discloses a retroreflector having a light-impermeable convex portion on the surface. However, although this member selectively reflects light, it is not possible to set the reflection directivity in which the reflectance is distributed according to the incident angle and the incident direction.

  It is also possible to control the reflecting surface in an appropriate direction according to the position of the sun using power such as a motor. However, in this case, since a drive unit for controlling the reflecting surface is necessary, the apparatus configuration is complicated, and when used outdoors, it causes a failure.

JP 2006-322313 A JP 2006-317648 A JP-A-8-189161 JP 2007-279595 A JP 2009-122424 A JP 2005-41120 A JP 61-46976 A JP 2006-163239 A

The above-described optical reflector has an incident angle dependency on the reflectance, but cannot be set with a distribution of the reflectance depending on the incident angle and the incident direction. Also, it is not suitable for use over a wide area outdoors as a wall surface of a building, such as a drive unit is required, power is required, the structure of the member is complicated, light resistance is poor, materials are expensive, etc. There are also many.
Therefore, the problem of the present invention is that there is no drive unit, no power is required, and it is possible to increase the reflection without causing a problem of reflection with respect to the summer sun with a simple configuration and to reduce the heating load in winter. Furthermore, it is possible to provide a directional reflective material and a building material using the same that do not reflect light from below in the direction of the light source, that is, can effectively control irradiation light such as sunlight or reflected light. There is to do.

  As a result of intensive studies, the present inventors have found that the reflectance of the retroreflective material has a reflectance distribution, thereby changing the reflectance of incident light according to the incident angle and the incident azimuth. Was completed. That is, the present invention is as follows.

  The directional reflective material of the present invention includes a support layer, a reflective layer having a reflectance distribution, and a condenser lens.

  The incident angle of summer sunlight is different from the incident angle of winter sunlight. Even if the date and time are the same, if the geographical position such as latitude and longitude is different, the incident angle of sunlight is different. In the present invention, the design of the reflectance can be easily changed according to the location, height, direction, etc. where the directional reflective material is used. That is, since the reflection layer has a reflectance distribution, the reflection directivity can be easily changed without adjusting the support layer and the condenser lens. Therefore, the reflectance distribution can be designed according to the place where the directional reflective material is used. As a result, in summer, solar radiation is reflected efficiently and the amount of heat received by the building is reduced, so that the building is not warmed and the cooling load can be reduced. On the other hand, in winter, the solar radiation is absorbed efficiently, so that the heating load can be reduced. Furthermore, retroreflection of light from below, such as automobile headlights, can be prevented by controlling the reflectance distribution. Further, the reflectance can be controlled without changing the direction of the reflecting surface. As a result, there is no need for a drive unit for controlling the direction of the reflecting surface, so that the apparatus configuration can be simplified. In addition, problems such as failure do not occur.

  The reflectance distribution is formed by partially providing the light absorption layer on the reflection layer and / or providing light absorption layers having different light absorption rates.

  In this specification, the term “reflectance distribution” refers not only to the case where a part that reflects light and a part that absorbs light coexist, but also a part that reflects light and light. This includes a case where the degree of reflecting light or the degree of absorbing light is different in the site of the property. In addition, when the degree of light reflection or the degree of light absorption is different, even if the wavelength of the reflected or absorbed light is different in each part, even if the wavelength of the reflected or absorbed light is the same, Any case where the amount of light to be absorbed is different is included.

  The reflection layer has different reflectivity according to the incident angle of light.

  The directional reflective material may include a light absorbing portion and a reflective portion between the support layer and the reflective layer, and a control layer may be provided. The control layer can change the reflectance by, for example, sliding between the support layer and the reflective layer. As a result, the incidence / reflection of light can be controlled more finely.

  The condensing lens may be partially embedded in the reflective layer or provided on the reflective layer.

  The directional reflective material is used as a building material.

  The building material may be provided with a reflective layer having the reflectance distribution according to an annual solar trajectory at a point where the building material is provided. For example, the reflective layer at the position where sunlight is collected during the period during which the cooling load is generated is reflected so that the sunlight is collected at the part of the light absorbing layer during the period during which the heating load is generated. For example, a reflective layer having a reflectance distribution is provided.

  When the directional reflective material of the present invention is used for the building material, the light absorption layer has the reflectance distribution so that characters, patterns, colors, or combinations thereof are recognized when viewed from a specific direction. A reflective layer may be provided. In addition to effectively controlling irradiation light or reflected light, it can also be used for decorations such as wall surfaces.

  In the building material, the light absorbed by the light absorption layer may be used as a heat source or a power source.

The directional reflective material of the present invention includes a support layer, a reflective layer having a reflectance distribution, and a condenser lens. This reflective layer does not have a complicated structure, and the reflectance distribution can be arbitrarily changed. Therefore, it can be set as the structure which has the optimal reflectance by the place to use. Moreover, since no power is required and the configuration is simple, even if it is used outside such as building materials, it is inexpensive and has sufficient strength.
Furthermore, by providing a reflective layer having the reflectance distribution so that characters, patterns, colors, or combinations thereof can be recognized when viewed from a specific direction, decorativeness can be given to building materials and the like.

FIG. 1 is an explanatory view showing an outline of an embodiment of the directional reflective material of the present invention. FIG. 2 is an explanatory view showing an outline of an embodiment of the directional reflective material of the present invention. FIG. 3 is an explanatory view showing an outline of an embodiment of the directional reflective material of the present invention. FIG. 4 is an explanatory view showing an outline of an embodiment of the directional reflective material of the present invention. FIG. 5 is an explanatory view showing an outline of an embodiment of the directional reflective material of the present invention. FIG. 6 is a diagram for explaining the outline of one embodiment of the present invention. FIG. 7 is a diagram showing light reflection using a conventional retroreflective material.

(Embodiment 1)
Hereinafter, an embodiment of a directional reflective material of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view illustrating an example of an embodiment of a directional reflective material of the present invention. In FIG. 1, the directional reflective material includes a support layer 1, a reflective layer 2 having a reflectance distribution, and a condenser lens 3. The reflective layer 2 has a recess so that the condensing lens 3 is fitted on the surface thereof, and the light absorption layer 4 is provided on a part of the surface of the recess. By providing the light absorption layer 4 on a part of the surface of the recess, only light incident from a specific angle can be retroreflected and light incident at other angles can be absorbed. Moreover, in the example of this figure, the spherical condensing lens 3 is used.

(Support layer)
The support layer 1 is a layer for supporting other layers in the directional reflective material of the present invention. There is no restriction | limiting in particular about the material which comprises a support layer, Well-known building materials, such as a metal, concrete, glass, a tile, wood, resin, can be used. Further, the support layer may be light transmissive or light impermeable. Examples of such metals that can be used as building materials include iron, stainless steel, aluminum, and galvanium steel sheets. Glass includes quartz glass, soda-lime glass, lead glass, safety glass, tempered glass, crystallized glass, and porous glass. Is a resin, a polyolefin resin such as polyethylene and polypropylene, a polyester resin such as polyethylene terephthalate, a highly transparent resin such as polystyrene, polyurethane, polyvinyl chloride, an acrylic resin, and a polycarbonate, and these highly transparent resins And a light-impermeable resin obtained by adding a pigment or the like. Moreover, the cloth using the fiber which used fiber reinforced plastic and said resin as a raw material may be sufficient. The support layer may have, for example, a sheet-like, tile-like or block-like structure depending on the purpose of use.

(Reflective layer)
The reflective layer 2 is not particularly limited as long as it has a property of reflecting light, and is a metal, a resin film or a metal film such as aluminum deposited or pasted on a glass, a resin film containing a pigment or a dye, Examples thereof include glass, paints containing pigments and dyes. Further, for the purpose of protecting the reflective layer, the surface of the reflective layer may be coated with a transparent resin or the like. In addition, the resin film and glass containing a pigment and dye, and the coating material containing a pigment and dye may be in common with the following light absorption layer. In this specification, when a resin film containing a pigment or dye or a paint containing a pigment or dye is used for the purpose of reflecting light of a specific wavelength, it is called a light reflecting layer and absorbs light of a specific wavelength. In the case of using a resin film containing a pigment or a dye or a paint containing a pigment or a dye for the purpose, it may be called a light absorbing layer.

  In the example of FIG. 1, a light absorption layer 4 is provided on a part of the surface of the reflection layer. A part of the condenser lens 3 is embedded in the reflective layer 2. That is, the surface of the reflective layer 2 has a recess so that the condenser lens 3 is fitted on the reflective layer 2. In the example of FIG. 1, the light absorption layer 4 is partially provided on the surface of the concave portion of the reflective layer 2. Therefore, the portion having contact with the buried condenser lens 3 has a reflectance distribution depending on whether it is in contact with the reflection layer 2 or the light absorption layer 4.

(Light absorption layer)
The light absorption layer 4 is not particularly limited, and examples thereof include light absorbing pigments and dyes, metal oxides, and resins containing pigments and dyes. As described above, the light absorption layer 4 is provided on a part of the surface of the reflective layer.

  In the example of FIG. 1, the light absorption layer 4 is provided on a part of the surface of the reflection layer. On the other hand, it is good also as a structure which provides a reflection layer in a part of surface of a light absorption layer contrary to the example of FIG. Or it is good also as a structure which has a light absorption layer and a reflection layer on the same surface.

  The reflectance distribution can be given by changing the pattern of the light reflection layer and the light absorption layer for each condenser lens fitted as described above. On the other hand, the reflectance distribution can also be provided by combining the reflecting lenses corresponding to the individual condensing lenses with the same reflectance and combining the condensing lenses in contact with the reflecting layers having different reflectances. For example, of the 10 condenser lenses, the light reflecting layer is in contact with one condenser lens, and the light absorbing layer is in contact with the nine condenser lenses. In this case, fine control is difficult as compared with the case where the pattern of the light reflecting layer and the light absorbing layer is changed for each condensing lens to be fitted. However, the reflectance distribution can be given with a simple configuration.

(Condenser lens)
The condenser lens 3 is not particularly limited as long as it can collect light. In addition to the spherical (bead) -shaped microspheres as shown in FIG. 1, for example, hemispherical, semi-cylindrical, semi-cylindrical, polygonal (for example, triangular), spindle (conical, spindle, polygonal) (For example, a triangular pyramid, a quadrangular pyramid)). The microspherical condensing lens includes, for example, an elliptical spherical shape. The condensing lens 3 may have a cavity in the lens.

  The size of the condenser lens 3 is not particularly limited as long as it can collect light. In the case of using a spherical one, a particle having a particle size of about 30 μm or more may be used. This is because if the condenser lens 3 having a particle size smaller than about 30 μm is used, sunlight having a wavelength of about 0.3 μm to about 2.5 μm spreads by diffraction, and a desired reflectance distribution cannot be obtained. Moreover, the upper limit of the particle diameter of the condensing lens 3 is about 10 cm or less. If the particle size is larger than this, there is a problem that due to weight and thickness, it becomes unsuitable for use as a building material for the building skin, and there is a problem that the temperature rise due to light collection increases. The spherical condenser lens 3 may be a known glass bead or the like.

(Production method)
The directional reflective material in the present embodiment is manufactured, for example, as follows. A reflective layer 2 is manufactured by depositing a metal such as aluminum on the support layer 1. The metal film is formed with a concave depression on the surface of the metal film by, for example, injection molding, extrusion molding, embossing, or the like. A light absorption layer is partially provided in the concave depression.

  The light absorption layer plays an important role in the directional reflective material of the present invention. In the present invention, a light absorption layer is partially provided on the reflective layer. Specifically, the position (latitude / longitude) where the directional reflective material is provided, the height from the ground surface where the directional reflective material is provided, the direction where the directional reflective material is provided, and the surrounding conditions (for example, surrounding buildings, roads) In addition, the light absorption layer is arbitrarily patterned with respect to the solar altitude that changes periodically and regularly according to the season and time. For example, if it is desired to reflect sunlight in the summer or time zone to suppress the increase in temperature, the position where the sunlight is irradiated through the condenser lens 3 is set to be a highly reflective portion in the reflective layer. On the other hand, in a season or a time zone in which sunlight is absorbed and heat energy or light energy is desired, the position where the sunlight is irradiated through the condenser lens 3 is made to be the light absorption layer.

  Further, when the directional reflective material of the present invention is installed at a position where the installation surface faces the road and the headlight of an automobile or the like hits, the position where the light of the headlight is irradiated through the condenser lens Is made to be the light absorption layer 4. Further, from the height from the ground surface where the directional reflective material is provided, when there is a streetlight or the like in the installation of the directional reflective material of the present invention, the position where the light of the streetlight is irradiated through the condenser lens, The light absorption layer 4 is formed.

  You may provide the light absorption layer from which a light absorptivity differs. When dyes or pigments having different color tones, metal oxides, or the like are used, light absorption layers having different light absorption rates can be formed. In this case, for example, when a dye or pigment having a high absorption rate in the infrared region is used, the heat utilization efficiency of sunlight can be increased. Thereby, the heat utilization efficiency of sunlight can be improved.

  Alternatively, the light absorbing layer may be patterned with letters, patterns, colors, or combinations thereof. Thereby, for example, a wall surface or the like can be decorated, a wall surface that looks different depending on the viewing angle, an advertisement, or the like can be displayed. In this case, by changing the pattern of the light reflecting layer and the light absorbing layer for each condensing lens to be fitted, the reflectance of the reflecting layer corresponding to each condensing lens is made the same, and reflection having different reflectances is performed. A condensing lens in contact with the layers may be combined.

  The light absorption layer 4 can be formed by attaching a resin film having a pattern formed with a light absorption material on the light reflection material and transferring the light absorption material. Further, a light absorbing material may be printed on the light reflecting material.

  Next, the condensing lens 3 is embedded in the concave depression of the reflection layer provided with the light absorption layer 4. As a method for embedding the condensing lens 3, a suitable method may be employed depending on the size and shape of the diameter of the condensing lens. Specifically, in the case of a large condenser lens, an adhesive is applied to the surface of the light absorption layer, and then the condenser lens is placed. Or the thing with a small condensing lens apply | coats the dispersion liquid of the condensing lens 3 on a reflection layer. Thereafter, the surface of the reflective layer 2 is wiped off, and the condenser lens that is not embedded in the concave depression of the reflective layer 2 is collected.

(function)
When the directional reflective material of the present embodiment is used as a building material, it functions as follows. As shown in FIG. 1, first, when the solar altitude is high, such as summer sunlight, the position where the sunlight is irradiated through the condenser lens is the light reflecting layer. Thereby, sunlight is retroreflected. On the other hand, when the solar altitude is low like winter sunlight, the position where the sunlight is irradiated through the condenser lens is the light absorption layer. Thereby, sunlight can be heat-utilized. When light is incident from a low angle, such as a streetlight or a headlight of an automobile, the position where the light is irradiated through the condenser lens is the light absorption layer. Thereby, night visibility is not impaired.

  As described above, the directional reflective material of the present invention can change the reflectance of the reflective layer irradiated through the condenser lens according to the incident angle of light. In this specification, “the reflection layer has different reflectance depending on the incident angle of light” means that the reflectance of the reflective layer irradiated through the condenser lens varies depending on the incident angle of light. Means that.

(Embodiment 2)
The directional reflective material of the present invention is not limited to the above method as long as the structure of the directional reflective material of the present invention can be obtained. FIG. 2 is a conceptual diagram illustrating the configuration of the directional reflector according to the second embodiment. In the example of FIG. 2, paint is applied directly to the condenser lens a plurality of times to form a reflectance distribution in the reflective layer 2. When the support layer is made of concrete, the condensing lens may be embedded before the concrete is completely solidified in the concrete generation process. When the support layer is made of resin, the condensing lens may be embedded before solidifying in the resin production process or in a warmed and soft state. Moreover, you may fix to a support layer through an adhesive agent.

(Embodiment 3)
FIG. 3 is a conceptual diagram illustrating the configuration of the directional reflector according to the third embodiment. In the first embodiment, the support layer 1 is used. On the other hand, in this embodiment, the heat medium layer 5 is used instead of the support layer.

  The heat medium layer 5 may be a known solar water heater, for example. Thereby, the heat obtained from sunlight can be used more efficiently. Instead of the heat medium, a solar cell may be used to change the light into electricity.

(Embodiment 4)
FIG. 4 is a conceptual diagram illustrating the configuration of the directional reflector according to the fourth embodiment. As shown in FIG. 4, in the present embodiment, a control layer 7 is provided between the support layer 1 and the reflective layer 2. The control layer 7 includes a light reflecting portion 8 and a light absorbing portion 9. By adopting such a structure, for example, when it is desired to reflect sunlight, the control layer 7 is moved so that the light transmitted through the light transmission part 6 through the condenser lens 3 strikes the light reflection part 8. To do. On the other hand, when it is desired to absorb sunlight, the control layer 7 is moved so that light transmitted through the light transmission part 6 through the condenser lens 3 strikes the light absorption part 9. That is, according to this embodiment, it is possible to switch between when it is desired to actively use sunlight and when it is not desired to use it. Further, light incident from a low angle such as a headlight can be absorbed by the light absorption layer 4 as in the case of the first embodiment. The control layer 7 may be moved manually or may be moved by providing a drive unit (not shown).

  Moreover, in this figure, you may use the thermal-medium layer 5 and solar cell which were used in Embodiment 3 instead of the support layer 1. FIG. According to this configuration, even in the summer, if a light transmission part is provided at a position where the light is concentrated with respect to the summer solar altitude, it can be effectively used as a heat source or a power source.

  When the directional reflector of this embodiment is used, various uses are possible. For example, even when the solar altitude is high as in the summer, when the solar altitude is relatively low such as early morning, if a light absorbing material that supplies only the wavelength that affects the luminous intensity to the light absorbing portion 9 is used, The temperature rise can be suppressed and the room can be brightened. On the other hand, when the solar altitude is high, it acts as a blind.

  The light transmission part 6 may be formed, for example, as a highly transparent resin, a highly transparent material such as glass among the resins forming the support layer, or as an air layer formed in a cavity.

  The control layer 7 is configured by combining the light absorbing material and the light reflecting material. Alternatively, it can be formed by providing a light reflecting material on a part of the surface of the light absorbing material or providing a light absorbing material on a part of the surface of the light reflecting material.

(Embodiment 5)
FIG. 5 is a conceptual diagram illustrating the configuration of the directional reflector according to the fifth embodiment. In the present embodiment, a flat reflective layer 2 composed of a light absorbing material and a light reflecting material is used. That is, the condensing lens 3 has a structure that is not embedded in the reflective layer 2. A flat transparent coating film 10 is provided on the surface of the condenser lens 3. By providing the transparent coating film 10 on the surface, the unevenness of the surface is eliminated and the surface becomes difficult to be contaminated. Further, the strength that can withstand wind and snow can be obtained.

  The transparent coating film 10 may be formed of, for example, a highly transparent resin among the resins forming the support layer or a highly transparent material such as glass. Moreover, you may attach a photocatalytic function to the surface of a transparent coating film. Thereby, durability can be given by decomposing | disassembling the contaminant from the outside. As described above, a surface protection method used for a known retroreflective material called an encapsulated lens type or a capsule lens type may be used.

  Each of the above embodiments may be used alone or in any combination.

  The directional reflective material of the present invention is characterized in that the design can be arbitrarily changed to reflect or absorb the light according to the angle and direction of the incident light depending on the installation location. For this reason, it is not affected by the place where it is installed, and it can be installed on a vertical surface, a horizontal surface, or an angled surface to effectively control light absorption / reflection. . In addition, the structure is simple and can be manufactured at low cost. Furthermore, application is easy.

  Such a directional reflective material of the present invention is, for example, a vertical surface such as an outer wall of a building, a surface having an angle such as a roof or a roof, a horizontal surface, a corridor, a veranda, an indoor floor surface, a blind, a curtain, an awning. It can also be used for construction materials such as (awnings) and fences, and civil engineering materials such as the ground, roads and water bottoms.

  In the directional reflective material of the present invention, the reflectance distribution can be designed in consideration of individual installation locations according to structures such as buildings. Alternatively, a tile-shaped directional reflective material having a plurality of types of reflection and absorption modes according to the incident angle may be prepared. What is necessary is just to install the suitable tile-shaped directional reflective material from the installation position of solar altitude or a directional reflective material. If a tile-shaped directional reflective material is used, it does not cost individually to design and can be used easily.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
(Formation of directional reflective material)
A transparent soda-lime glass sphere having a diameter of 12.5 mm was used as the condenser lens. Glass spheres were spread on the horizontal surface in one layer to form a reflectance distribution in the hemisphere. First, after masking with a hole with a diameter of 6 mm on the convex part of the hemisphere, a metallic luster paint (Asahi pen-plated synthetic resin paint, solar reflectance 64.0%, according to JIS R3106) is applied, and a reflection with a diameter of 6 mm is applied. A layer was formed. Thereafter, a black paint (Nippe Home Products synthetic resin paint glossy black, solar reflectance 3.7%, according to JIS R3106) was applied to the remaining part of the hemisphere to form a light absorption layer.

(Formation of support layer)
The directional reflective material of Example 1 was adhered to the obtained reflective layer provided with the condenser lens with an epoxy resin (epoxy adhesive aldite: manufactured by Huntsman Japan Co., Ltd.) using an aluminum plate as a supporting layer. Produced.

(Comparative Example 1)
After the same glass spheres as in Example 1 were laid down on the horizontal surface in one layer, the metallic luster paint was applied to all hemispherical parts without masking. A support layer was bonded to the reflective layer provided with the condenser lens in the same manner as in Example 1 to produce a reflective material of Comparative Example 1.

(Comparative Example 2)
Without using a condensing lens, a black paint was directly applied to the aluminum plate used as the support layer in Example 1 to obtain a coating sample consisting of only a light absorbing layer having no retroreflectivity.

(Measurement and evaluation method)
(Performance evaluation)
The obtained test piece was subjected to an irradiation test using an artificial light source as shown in FIG. 6 in order to evaluate the performance of controlling heat absorption and reflection by the incident angle.

  As shown in FIG. 6, in a laboratory set at a room temperature of 25 ° C., each test piece of Example 1, Comparative Example 1 and Comparative Example 2 (63 mm × 56 mm in size) was cut to a thickness of 30 mm. Infrared lamp with a distance of 300mm to 60W, installed horizontally on the heat insulating material, under two conditions of an incident angle of 70 ° (equivalent to the solar altitude in summer) and an incident angle of 40 ° (equivalent to the solar altitude in winter) with respect to the horizontal plane (Toshiba IRYO 100 / 110V60WR, near-infrared lamp having an output peak at a wavelength of 700 to 1400 nm) was irradiated, and the sample surface temperature was measured with a thermocouple attached to the center of the support layer of each sample. Table 1 shows the sample surface temperature when the temperature rise 40 minutes after the start of irradiation of the sample almost reached equilibrium.

  In Table 1 above, “Yes” indicates that the temperature of the sample surface does not increase and the incident light is reflected, and “No” indicates that the temperature of the sample surface increases. This means that the incident light is absorbed.

  From Table 1, the directional reflective material of Example 1 reflects light when the incident angle is 70 °, and the temperature of the sample surface does not increase, and a temperature suppressing effect is recognized. On the other hand, when the incident angle is 40 °, light is absorbed, the temperature of the sample surface rises, and the temperature suppression effect is not recognized. That is, it can be seen that the directional reflective material of Example 1 has different light reflectivities between the light absorption layer and the light reflection layer, and can reflect and absorb light according to the incident angle.

  Since the comparative example 1 which is an example of the current retroreflective material reflects incident light regardless of the incident angle, the temperature of the sample surface does not increase at both the incident angle of 70 ° and the incident angle of 40 °. It can be seen that the light is reflected.

  Since all of the light absorption layers in Comparative Example 2 absorb incident light regardless of the incident angle, the temperature of the sample surface rises at both the incident angle of 70 ° and the incident angle of 40 °. You can see that it absorbs.

DESCRIPTION OF SYMBOLS 1 Support layer 2 Reflective layer 3 Condensing lens 4 Light absorption layer 5 Heat medium layer 6 Light transmission part 7 Control layer 8 Light reflection part 9 Light absorption part 10 Transparent coating film 20 Support layer 21 Reflection layer 22 Condensing lens

Claims (9)

  A directional reflective material comprising a support layer, a reflective layer having a reflectance distribution, and a condenser lens.   The directional reflective material according to claim 1, wherein a reflectance distribution is formed by partially providing the light absorbing layer on the reflective layer and / or providing light absorbing layers having different light absorption rates.   The directional reflective material according to claim 2, wherein the reflective layer has a reflectance that varies depending on an incident angle of light.   The directional reflective material according to any one of claims 1 to 3, wherein a control layer having a heat absorption part and a heat reflection part is provided between the support layer and the reflection layer.   5. The directional reflecting material according to claim 1, wherein a part of the condensing lens is embedded in the reflecting layer or provided on the reflecting layer.   A building material using the directional reflective material according to claim 1.   The building material according to claim 6, wherein a reflective layer having the reflectance distribution is provided according to an annual solar trajectory at a point where the building material is provided.   The building material according to claim 6, wherein the light absorbing layer is provided with a reflective layer having the reflectance distribution so that characters, patterns, colors, or combinations thereof are recognized when viewed from a specific direction. . The building material according to claim 6, wherein the light absorbed by the light absorption layer is used as a heat source or a power source.

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