JP2007079452A - Light distribution control reflective sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light distribution control reflective sheet that suppresses a rise in temperature in a closed space even in the presence of the sunshine by reflecting light entering the closed space to outside the closed space and does not dazzle a person in the closed space. <P>SOLUTION: Disclosed is the light distribution control reflective sheet installed in the closed space, the light distribution control reflective sheet having, on at least one surface, a plurality of ridges which are sectioned in a nearly triangular shape so that one slope is a slat type reflective surface and the other slope is a slat type non-reflective surface and the internal angle, size, and array of the ridges being defined so that reflective surfaces reflect light entering the closed space to outside the closed space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light control reflection sheet, and more particularly to a light control reflection sheet for installation on a substantially horizontal surface in a closed space.

  It is well known that in a sunshine, the enclosed space of a vehicle becomes very hot. If it gets on in such a situation, it will become unpleasant because a crew member will receive hot air, cooling efficiency will also fall, and excessive energy consumption will become a problem.

  Under sunshine, the temperature rise in the vehicle is caused by the surface of the interior material of the vehicle absorbing light energy, converting it into heat energy, and storing it, resulting in high temperature of the member, heat transfer from the high temperature member, and heat dissipation. In particular, the upper surface of the dashboard of a car is finished with a textured material (such as satin embossing) with a dark-colored material so that the sun's reflection does not become dazzling when viewed from the driver. However, a surface finish that suppresses such reflections, on the other hand, results in promoting sunlight absorption, and the dashboard top surface is very hot. Temperature rise in the vehicle is promoted by radiant heat from the dashboard surface that has become hot or heat transfer from the dashboard itself that has been hot.

  On the other hand, it is conventionally known to control the progress of light using a prism. For example, Patent Document 1 describes a sheet material to which a peeping prevention function is added by arranging a large number of linear prisms in parallel and defining the light transmission direction. This sheet material must transmit light incident from a predetermined direction, and the prism must be transparent.

  Patent Document 2 describes an orientation control reflecting sheet for illumination use using a linear prism-like mirror. The linear prism of this reflecting sheet has two inclined surfaces that are reflecting surfaces.

  Patent Document 3 describes a reflective skin material that can prevent heating of the interior material surface during parking in hot weather. This reflective skin material has a reflective layer that reflects light and an angle-selective transmissive layer having a number of parallel linear prisms laminated on the reflective layer. A light shielding wall is provided on one slope of the linear prism.

However, in this reflective skin material, light entering the vehicle from the sun or the like passes through the angle-selective transmission layer before and after being reflected by the reflection layer, so that light energy is absorbed at that time. Further, when light hits the light shielding wall, most of the light energy is absorbed. Therefore, this reflective skin material is inferior in the light reflection efficiency, and the heating suppression effect is insufficient.
Japanese National Patent Publication No. 10-501900 JP-A-6-36608 JP-A-2005-186385

  The present invention solves the above-mentioned conventional problems, and the object of the present invention is to reflect the light incident in the closed space toward the outside of the closed space, so that the temperature in the closed space is maintained even under sunlight. An object of the present invention is to provide a light distribution control reflection sheet that can suppress the rise and that does not make a person in the enclosed space feel glare.

  The present invention relates to an orientation control reflecting sheet installed in a closed space, having a ridgeline, having a substantially triangular cross section, one inclined surface being a slat-like reflecting surface, and the other inclined surface being a slat-like non-reflecting surface A plurality of ridges on at least one side, and the interior angle, size, and arrangement of the ridges are configured such that the reflecting surface reflects light incident in the enclosed space toward the outside of the enclosed space. A light control reflective sheet is provided, whereby the above object is achieved.

  Moreover, this invention provides the method of suppressing the temperature rise in the vehicle by light absorption including the process of installing the said light distribution control reflective sheet, The said objective is achieved by it.

  Since the light distribution control reflecting sheet of the present invention can reflect light incident in the enclosed space with high efficiency outside the enclosed space, a substantially horizontal surface in the enclosed space that has generated a large amount of radiant heat until now. If it installs in, the temperature rise in a closed space will be suppressed effectively. Moreover, since the reflected light does not enter the human field of view, the person in the enclosed space does not feel glare.

  FIG. 1 is a cross-sectional perspective view of a light distribution control reflecting sheet according to an embodiment of the present invention. This light distribution control reflection sheet 100 has a plurality of ridges 101, 101 ', ... on one side. This ridge has a triangular cross section, and has a ridgeline 102 and two slopes sandwiching it. Each slope has a slender slat shape.

  Of the slopes, the reflecting surface 103 has a light reflecting layer thereon (not shown in the figure). This light distribution control reflection sheet is installed in a closed space, for example, on a plane in a vehicle (for example, on a substantially horizontal surface). Light that enters the enclosed space from the sun or the like is reflected by the reflecting surface 103 and is not absorbed by the light distribution control reflecting sheet. Therefore, this light distribution control reflecting sheet has almost no energy accumulation and can suppress the rise in surface temperature. Therefore, radiation and heat transfer to the enclosed space are reduced, and the enclosed space can be used even under sunlight. The temperature inside is not substantially increased.

  The reflecting surface 103 is sufficient if it has a function of reflecting light appropriately, and need not be a flat surface, but may be a concave surface. In other words, the cross section of the ridge does not necessarily have to be a triangle composed of straight lines. FIG. 2 is a partial cross-sectional view of a light distribution control reflecting sheet which is another embodiment of the present invention.

  The light reflecting layer is typically a specular reflecting layer. In this case, the thickness of the reflective layer is selected so that the reflectance of the reflective layer is as high as possible, and is usually 200 angstroms or more, preferably 400 angstroms or more.

The specular reflection layer is a layer that reflects light having a wavelength of 400 nm or more. For example, metals such as aluminum, silver, platinum, nickel, tin, copper, rhodium, chromium, lead, palladium, molybdenum, tungsten, gold, or combinations thereof can be included. Reflects metal oxides such as SnO ₂ , ZnO, In ₂ O ₃ , or films such as SnO ₂ : F, SnO ₂ : Sb, ITO, ZnO: Al, and ZnO: Ga, which are doped metal oxides thereof. It may be used as a layer.

The reflective layer includes Na ₂ AlF ₆ , MgF ₂ , SiO ₂ , SiO, Al ₂ O ₃ , CeF ₃ , PbF ₂ , Nd ₂ O ₃ , ZrO ₂ , TiO ₂ , CeO ₂ , ZnS, ZnSe, CdTe. A non-metal such as a multilayer dielectric laminate in which films of Si, Ge, PbTe, etc. are laminated may be included. Such layers can be deposited by physical or chemical deposition techniques, such as vacuum deposition, sputtering, chemical vapor deposition (CVD) or plasma enhanced CVD, electroless deposition, etc., depending on the type of film desired.

  Certain films can comprise multiple layers, including layers that promote adhesion to the body layer, the barrier layer, and the protective overcoat layer. For example, a suitable film for a polycarbonate based substrate includes an approximately 1 nm thick titanium dioxide layer formed by sputtering titanium onto the body layer, followed by a 100 nm thick aluminum vaporized layer. The titanium dioxide layer acts as both an adhesion promoter and a barrier layer to counteract the effects of pinholes typically present in aluminum deposited coating layers.

  The light reflecting layer may be formed of a light transmissive material having a higher refractive index than that of the light transmissive polymer, or a multilayer reflective film to which reflectivity is imparted using light interference.

  The non-reflective surface 104 is a surface that absorbs or transmits light. The direction and dimensions of the non-reflective surface 104 are determined such that a person's line of sight in the closed space hits the non-reflective surface 104 when installed in the closed space.

  In this case, outside light that enters from outside the enclosed space usually does not hit the non-reflecting surface, but hits the reflecting surface and is reflected outside the vehicle, but even if the reflected light hits the non-reflecting surface, it is directed toward the human line of sight. The person in the enclosed space does not feel glare.

  Typically, a dark color layer or a black color layer is formed on the non-reflective surface (not shown in the figure). What is necessary is just to form a dark color layer etc. using a normal paint and a coloring material. The non-reflecting surface may be subjected to conventional surface treatments such as matting, embossing and roughening. The prism-shaped ridge itself may be formed of a dark or black material, and if the non-reflective surface transmits light, a dark color layer or a black layer may be formed on the entire bottom surface of the light distribution control reflection sheet. In this case, it is not necessary to separately form a dark color layer or a black layer on the non-reflecting surface.

  The internal angle of the prism-shaped rod, that is, the internal angle, size, and arrangement of a triangle that is a cross-section cut by a plane perpendicular to the length direction, so that the reflecting surface reflects incident light toward the outside of the vehicle. It is configured. For example, they are configured to be incident at an angle of -20 ° to 70 ° of incident light by the sun, and to return 70% or more of the reflected light to a range of -20 ° to 100 °.

  The size of the ridge may be adjusted as appropriate. Generally, the height h is 10 to 5000 μm, preferably 20 to 2000 μm, and the width w is 20 to 5000 μm, preferably 40 to 3000 μm. If the height h is less than 10 μm, it is difficult to produce and the reflection efficiency is lowered, and if it exceeds 5000 μm, the appearance is poor and the design is adversely affected. If the width w is less than 20 μm, the production is difficult, and if it exceeds 3000 μm, the appearance is poor and the design is adversely affected. All the dimensions of the ridges may be the same, and may be changed for each individual ridge. In the example of FIG. 1, the dimensions of the ridges are a height h of 27.3 μm and a width w of 50 μm.

  The distance p between the prismatic ridges may be the same as or different from the width w of the ridges. However, when the distance p is less than the width w, the shape of the ridge cannot be maintained, and when the distance p exceeds the width w, a flat portion is generated and the degree of light distribution control reflection tends to be reduced. In the example of FIG. 1, the distance p between the prisms is 50 μm, which is the same as the width w. The distances p of the ridges may all be the same, and may be changed for each ridge.

  The inner angles α, β and γ of the kite may be determined in consideration of the installation angle, the position of the human eye in the enclosed space, and the solar altitude. The installation angle and the position of human eyes in the enclosed space vary depending on the application of the light distribution control reflection sheet (for example, for a house, a vehicle, or a vehicle) and a specific installation location. In addition, the solar altitude changes during the time when the altitude in the south and the air temperature rises according to the latitude of the installation location. For this reason, it is not appropriate to uniquely determine the value of the inner angle of the heel.

  For example, the inner angle of the ridge is adjusted so that the reflecting surface forms an angle of 20 to 45 ° with respect to the horizontal plane in a state where the sheet is installed in the sealed space. Alternatively, the inner angle of the ridge is adjusted so that the non-reflecting surface forms an angle of 70 to 100 ° with respect to the horizontal plane in a state where the sheet is installed in the sealed space.

  In a preferred embodiment, the inner angle β is 20 to 45 °, preferably 25 to 37 °. If the interior angle β is less than 20 °, the reflected light may enter the vehicle, and if it exceeds 45 °, the reflected light is absorbed by the adjacent eyelid. The inner angle γ is 70 to 100 °, preferably 75 to 95 °, more preferably 78 to 93 °. If the internal angle γ is less than 70 °, reflection becomes inappropriate due to the south / middle altitude, and if it exceeds 100 °, it is difficult to perform die cutting during production. The inner angles of the ridges may all be the same, and may be changed for each individual ridge. In the example of FIG. 1, the internal angles α, β, and γ are 71 °, 32 °, and 77 °, respectively.

  The thickness d of the light distribution control reflection sheet may be appropriately determined according to the material and purpose. In general, the thickness d is 0.1 to 7 mm, preferably 0.1 to 2 mm. When the thickness d is less than 0.1 mm, it is difficult to handle the sheet, and when it exceeds 2 mm, there is a problem in the weight and flexibility of the sheet. In the example of FIG. 1, the thickness d of the light distribution control reflection sheet is 150 μm.

  The light distribution control reflecting sheet can be made of a material usually used for manufacturing this type of optical element such as a linear prism sheet. However, the material constituting the light distribution control reflection sheet need not be light transmissive. Specific examples of materials include polycarbonate, polymethyl methacrylate, polyalkyl (meth) acrylate, polystyrene, acrylic epoxy, acrylic urethane, acrylic polyester, cellulose ester, polyvalent (meth) acrylate, vinyl chloride and urethane. is there.

  FIG. 3 is a cross-sectional perspective view of a light distribution control reflecting sheet which is another embodiment of the present invention. The light distribution control reflecting sheet shown in FIG. 1 is waved in the length direction of the ridges to form corrugated peaks and valleys on the reflecting surface. By making the reflecting surface of the light distribution control reflecting sheet into a curved surface in this way, it is possible to prevent the sheet from being viewed from the outside of the vehicle.

  FIG. 4 is a partial cross-sectional view of a light distribution control reflecting sheet which is another embodiment of the present invention. In FIG. 4A, a reflection control layer 405 is provided on the ridges of the light distribution control reflection sheet shown in FIG. A reflection control layer 405 is formed on the light reflection layer 410 at the reflection surface 403. The reflection control layer 405 may be a transparent resin layer that has a function of scattering transmitted light. In FIG. 4B, an uneven resin layer 406 is formed on the ridge, and a light reflecting layer 411 is formed thereon. The uneven resin layer may not be transparent.

  By forming the reflection control layer 405 and the concavo-convex resin layer 406, the sheet can be prevented from being dazzled from the outside of the vehicle. Further, a commonly used functional layer such as a protective layer may be formed on the ridge.

  These light distribution control reflection sheets are used by being installed on a substantially horizontal surface in a closed space, for example, a closed space of a house or a vehicle. Examples of the vehicle include automobiles, railroads, ships, and airplanes. Further, examples of the substantially horizontal surface include an upper dashboard panel in front of the driver's seat (cockpit), an automobile dashboard upper surface, and a rear parcel shelf board.

Example 1
A linear prism sheet (“IDFII” manufactured by 3M) having the dimensions and shape shown in FIG. 1 was prepared. The non-reflective surface 104 of this sheet was painted with a black marker, and an aluminum film was deposited on the reflective surface 103 to a thickness of about 100 nm to obtain a light distribution control reflective sheet.

  On the other hand, a general vinyl chloride interior sheet for passenger cars was prepared. This interior sheet is black and has a textured surface (such as satin embossing).

Both sheets were adjusted to obtain an irradiation intensity of 900 W / cm ^{2 on} the sample surface using an artificial solar lamp (“XC-500TPF” manufactured by Celic), and the sheet installation angle was 18 ° (sheet The incident angle was 72 [deg.]. Table 1 shows the results of measuring the sheet surface temperature 30 minutes and 60 minutes after irradiation.

[Table 1]

  Thus, the light distribution control reflection sheet had a smaller increase in surface temperature due to light irradiation than the vinyl chloride interior sheet.

  Moreover, when this light distribution control reflection sheet was placed on the dashboard of a passenger car, it looked black to the driver and the sun was not bright.

Example 2
Sheet molding (thickness t = 1.6 mm) was performed using “Perprene P90B (colorless)” manufactured by Toyobo Co., Ltd., and in the shape shown in FIG. 1, P = W = 1 mm, α = 82 °, β A linear prism sheet with 30 ° and γ = 78 ° was prepared. This sheet is made of an opaque milky white resin. An aluminum film was deposited on the reflective surface 103 of the ridge so as to have a thickness of about 100 nm to obtain a light distribution control reflective sheet (2).

Next, a SiO ₂ diffusion protective layer having a thickness of about 1 μm was applied on the aluminum film of the light distribution control reflection sheet (2) to obtain a light distribution control reflection sheet (3).

  The light distribution control reflection sheet (2), the light distribution control reflection sheet (3), and aluminum in the same manner as in Example 1 except that the installation angle of the sheet is 30 ° (the incident angle to the sheet is 60 °). The linear prism sheet before film deposition was irradiated. Table 2 shows the results of measuring the sheet surface temperature 30 minutes and 60 minutes after irradiation.

[Table 2]

  The linear prism sheet before vapor deposition of the aluminum film was milky white and the temperature increase width was small, but the light distribution control reflection sheets (2) and (3) had a smaller surface temperature increase width due to light irradiation.

Example 3
Sheet molding (thickness t = 1.6 mm) was performed using “Perprene P70B (black)” manufactured by Toyobo Co., Ltd., and in the shape shown in FIG. 1, P = W = 1 mm, α = 82 °, β A linear prism sheet with 30 ° and γ = 78 ° was prepared. This sheet is made of black resin. An aluminum film was deposited on the reflective surface 103 of the ridge so as to have a thickness of about 100 nm to obtain a light distribution control reflective sheet (4).

  The light distribution control reflection sheet (4) and the linear prism before vapor deposition of the aluminum film are performed in the same manner as in Example 1 except that the installation angle of the sheet is 30 ° (the incident angle to the sheet is 60 °). The sheet was irradiated. Table 3 shows the results of measuring the sheet surface temperature 30 minutes and 60 minutes after irradiation.

[Table 3]

  Thus, the light distribution control reflection sheet (4) had a surface temperature increase by light irradiation of about 15 ° C. smaller than the linear prism sheet before the aluminum film was deposited.

  When this light distribution control reflection sheet (4) was placed on the dashboard of a passenger car, it looked black to the driver and the sun was not bright.

Example 4
With respect to the light distribution control reflection sheet (4) obtained in Example 3, the reflection luminance from both the reflection surface side of the light distribution control reflection sheet and the non-reflection surface side of the light distribution control reflection sheet under the condition of an incident angle of 30 °. Were measured at various angles using an Apex Co., Ltd. declination photometer “AGM-01”. Halogen light was used as the light source, and “BM9” manufactured by Topcon Corporation was used as the luminance meter.

Thereafter, the reflection luminance from the light distribution control reflection sheet was measured in the same manner except that the incident angle of light was set to 60 °.

  A flat sheet of the same black resin as used in Example 3 was prepared. On the one surface, an aluminum film was deposited so as to have a thickness of about 100 nm to obtain a planar light reflecting sheet. For the planar light reflecting sheet, the luminance from the incident point was measured at various angles in the same manner as described above. The definition of the angle is shown in FIG. The measurement results are shown in Tables 4 and 5.

[Table 4]

Light incident from outside the enclosed space (+ angle) is reflected outside the enclosed space (+ angle) by the light distribution control reflection sheet, and hardly reflected inside the enclosed space (− angle). On the contrary, in the planar reflection sheet, light incident from outside the closed space (+ angle) is reflected into the closed space (− angle) by specular reflection (regular reflection).

[Table 5]

  Table 5 shows the measurement results of the reflection luminance of the light incident perpendicularly from directly above each sample sheet. Since there is a light source, light reflected in the vertical direction cannot be received (measured). Therefore, although there is no luminance data at an angle at which the flat reflection sheet gives the highest luminance, it can be seen that the flat reflection sheet is reflected straight to the light source side.

  On the other hand, in the light distribution control reflection sheet, it is shown that the direction of the reflected light is controlled in one direction (in this case, the angle direction of 50 to 60 °) depending on the design shape.

  Thus, it can be seen that the reflected light from the incident sunlight is effectively prevented from directly entering the eyes of a human being in a closed space such as in a passenger car. Therefore, even if it is installed on a passenger car dashboard, it is not dazzling for the driver.

Reference example 1
A sealed heat insulating box having a volume of about 10,650 ml (220 mm × 220 mm × 220 mm) was made of polystyrene foam, and a window of 250 × 250 mm clear laminated glass (thickness t = 5 mm) was provided on the upper lid.

  An aluminum-deposited PET film with an adhesive (PET 50 μ, total thickness 80 μ) was laminated on a transparent PVC sheet (thickness 15 mm) to prepare a flexible reflective film. This sheet was cut into 150 × 150 mm, and fixed on a polystyrene foam plate (thickness 20 mm) of the same size so that the transparent PVC sheet was exposed.

The obtained laminate was placed in a heat-insulating box with the surface of the transparent PVC sheet facing upward and an angle of 30 ° (corresponding to a solar altitude of 60 °) with respect to the bottom of the box. The top cover of the heat insulation box was closed, and irradiation was performed through the window of the top cover so as to obtain an irradiation intensity of 900 W / cm ^{2 on} the surface of the sample using an artificial solar lamp (“XC-500TPF” manufactured by Celic). The surface temperature and back surface temperature of the reflective film were measured over time.

  The reflective film was separated from the laminate, and fixed to the same expanded polystyrene plate (thickness 20 mm) so that the aluminum surface was exposed. The obtained laminate was placed in an insulated box with the aluminum surface facing upward and an angle of 30 ° (corresponding to a solar altitude of 60 °) with respect to the bottom of the box. The upper lid of the heat insulation box was closed, and irradiation was performed in the same manner as described above, and the surface temperature and the back surface temperature of the reflective film were measured over time. The measurement results are shown in FIG.

[Table 6]

  If a thick film is present on the upper part of the reflecting surface, absorption and temperature rise occur even with transparent resins. The temperature rise is suppressed by bringing the vapor deposition (reflection) surface to the light source side. This effect can be reduced if the resin layer is as thin as several tens of microns or less, but if the resin layer is thin, it is difficult to produce a light distribution control effect.

Reference example 2
A retroreflective sheet ("Scotchlite ^TM diamond grade conspicuity sheet 981-10 (white)" manufactured by 3M) was prepared. FIG. 6 is a cross-sectional view showing the configuration of the retroreflective sheet. There is a gap 604 below the retroreflective structure layer 601, and a sealing film 602 and an adhesive layer 603 for forming the gap 604 are formed.

  On the exposed surface of the transparent resin layer of the retroreflective sheet, a louver film (light control film (LCF) manufactured by 3M “188T 18UB90 (louver installation angle 18 °), hereinafter referred to as LCF18”)) is a transparent acrylic adhesive (thickness). t = 90 μm).

The retroreflective sheet laminated with LCF was adjusted to obtain an irradiation intensity of 900 W / cm ^{2 on} the sample surface using an artificial solar lamp (“XC-500TPF” manufactured by Celic), and the sheet installation angle Were irradiated under the conditions of 18 ° (the incident angle to the sheet was 72 °) and 0 ° (the incident angle to the sheet was 90 °). The sheet surface temperature was measured 60 minutes after irradiation.

Instead of LCF18, a louver film having a louver installation angle of 0 ° (3M light control film (LCF) “188T 0UB90 (louver installation angle of 0 °), hereinafter referred to as LCF0”) was used in the same manner as above. A retroreflective sheet laminated with LCF was obtained. This was similarly irradiated and the sheet surface temperature was measured. The results are shown in Table 6.
Moreover, the retroreflective sheet before providing an LCF resin layer was irradiated similarly, and the sheet surface temperature was measured. The results are shown in Table 7.

[Table 7]

It is a section perspective view of the light distribution control reflective sheet which is one embodiment of the present invention. It is a fragmentary sectional view of the light distribution control reflective sheet which is other embodiments of the present invention. It is a cross-sectional perspective view of the light distribution control reflection sheet which is another embodiment of the present invention. It is a fragmentary sectional view of the light distribution control reflective sheet which is other embodiments of the present invention. It is the graph which showed the time-dependent change of the reflective film temperature under irradiation. It is sectional drawing which showed the structure of the retroreflection sheet. It is the schematic diagram explaining the significance of the angle shown in the Example.

Explanation of symbols

100: Light distribution control reflection sheet,
101 ... 畝,
102 ... Ridge line,
103 ... reflective surface,
104: Non-reflective surface.

Claims (6)

An orientation control reflecting sheet installed in a closed space,
It has a plurality of ridges having a ridgeline, a cross-section having a substantially triangular cross-section, one inclined surface being a slat-like reflecting surface, and the other inclined surface being a slat-like non-reflecting surface. The light distribution control reflecting sheet, wherein the array is configured such that the reflecting surface reflects light incident in the closed space toward the outside of the closed space.   The light distribution control reflecting sheet according to claim 1, wherein the ridges are arranged so that ridge lines or valley lines of the ridges are substantially parallel to each other. The light distribution control reflecting sheet according to claim 1 or 2, wherein the reflecting surface forms an angle of 20 to 45 with respect to a horizontal plane in a state where the sheet is installed.   The light distribution control reflection sheet according to any one of claims 1 to 3, wherein the non-reflection surface forms an angle of 70 to 100 degrees with respect to a horizontal plane in a state where the sheet is installed. The reflective surface is
(A) A valley is formed by waving in the length direction, or (b) having a reflection control layer formed thereon.
The light distribution control reflection sheet according to claim 1, which has a reflection control function according to claim 1. The method to suppress the temperature rise in the vehicle by light absorption including the process of installing the light distribution control reflective sheet in any one of Claims 1-5 on the substantially horizontal surface in a vehicle.

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